Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

42 files changed, 19285 insertions, 0 deletions

diff --git a/fs/nilfs2/Makefile b/fs/nilfs2/Makefile
new file mode 100644
index 00000000000..df3e62c1ddc
--- /dev/null
+++ b/fs/nilfs2/Makefile
@@ -0,0 +1,5 @@
+obj-$(CONFIG_NILFS2_FS) += nilfs2.o
+nilfs2-y := inode.o file.o dir.o super.o namei.o page.o mdt.o \
+	btnode.o bmap.o btree.o direct.o dat.o recovery.o \
+	the_nilfs.o segbuf.o segment.o cpfile.o sufile.o \
+	ifile.o alloc.o gcinode.o ioctl.o gcdat.o
diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
new file mode 100644
index 00000000000..d69e6ae5925
--- /dev/null
+++ b/fs/nilfs2/alloc.c
@@ -0,0 +1,504 @@
+/*
+ * alloc.c - NILFS dat/inode allocator
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Original code was written by Koji Sato <koji@osrg.net>.
+ * Two allocators were unified by Ryusuke Konishi <ryusuke@osrg.net>,
+ *                                Amagai Yoshiji <amagai@osrg.net>.
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/bitops.h>
+#include "mdt.h"
+#include "alloc.h"
+
+
+static inline unsigned long
+nilfs_palloc_groups_per_desc_block(const struct inode *inode)
+{
+	return (1UL << inode->i_blkbits) /
+		sizeof(struct nilfs_palloc_group_desc);
+}
+
+static inline unsigned long
+nilfs_palloc_groups_count(const struct inode *inode)
+{
+	return 1UL << (BITS_PER_LONG - (inode->i_blkbits + 3 /* log2(8) */));
+}
+
+int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned entry_size)
+{
+	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+
+	mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS);
+	if (!mi->mi_bgl)
+		return -ENOMEM;
+
+	bgl_lock_init(mi->mi_bgl);
+
+	nilfs_mdt_set_entry_size(inode, entry_size, 0);
+
+	mi->mi_blocks_per_group =
+		DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode),
+			     mi->mi_entries_per_block) + 1;
+		/* Number of blocks in a group including entry blocks and
+		   a bitmap block */
+	mi->mi_blocks_per_desc_block =
+		nilfs_palloc_groups_per_desc_block(inode) *
+		mi->mi_blocks_per_group + 1;
+		/* Number of blocks per descriptor including the
+		   descriptor block */
+	return 0;
+}
+
+static unsigned long nilfs_palloc_group(const struct inode *inode, __u64 nr,
+					unsigned long *offset)
+{
+	__u64 group = nr;
+
+	*offset = do_div(group, nilfs_palloc_entries_per_group(inode));
+	return group;
+}
+
+static unsigned long
+nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group)
+{
+	unsigned long desc_block =
+		group / nilfs_palloc_groups_per_desc_block(inode);
+	return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block;
+}
+
+static unsigned long
+nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group)
+{
+	unsigned long desc_offset =
+		group % nilfs_palloc_groups_per_desc_block(inode);
+	return nilfs_palloc_desc_blkoff(inode, group) + 1 +
+		desc_offset * NILFS_MDT(inode)->mi_blocks_per_group;
+}
+
+static unsigned long
+nilfs_palloc_group_desc_nfrees(struct inode *inode, unsigned long group,
+			       const struct nilfs_palloc_group_desc *desc)
+{
+	unsigned long nfree;
+
+	spin_lock(nilfs_mdt_bgl_lock(inode, group));
+	nfree = le32_to_cpu(desc->pg_nfrees);
+	spin_unlock(nilfs_mdt_bgl_lock(inode, group));
+	return nfree;
+}
+
+static void
+nilfs_palloc_group_desc_add_entries(struct inode *inode,
+				    unsigned long group,
+				    struct nilfs_palloc_group_desc *desc,
+				    u32 n)
+{
+	spin_lock(nilfs_mdt_bgl_lock(inode, group));
+	le32_add_cpu(&desc->pg_nfrees, n);
+	spin_unlock(nilfs_mdt_bgl_lock(inode, group));
+}
+
+static unsigned long
+nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
+{
+	unsigned long group, group_offset;
+
+	group = nilfs_palloc_group(inode, nr, &group_offset);
+
+	return nilfs_palloc_bitmap_blkoff(inode, group) + 1 +
+		group_offset / NILFS_MDT(inode)->mi_entries_per_block;
+}
+
+static void nilfs_palloc_desc_block_init(struct inode *inode,
+					 struct buffer_head *bh, void *kaddr)
+{
+	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
+	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
+	__le32 nfrees;
+
+	nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode));
+	while (n-- > 0) {
+		desc->pg_nfrees = nfrees;
+		desc++;
+	}
+}
+
+static int nilfs_palloc_get_desc_block(struct inode *inode,
+				       unsigned long group,
+				       int create, struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(inode,
+				   nilfs_palloc_desc_blkoff(inode, group),
+				   create, nilfs_palloc_desc_block_init, bhp);
+}
+
+static int nilfs_palloc_get_bitmap_block(struct inode *inode,
+					 unsigned long group,
+					 int create, struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(inode,
+				   nilfs_palloc_bitmap_blkoff(inode, group),
+				   create, NULL, bhp);
+}
+
+int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
+				 int create, struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(inode, nilfs_palloc_entry_blkoff(inode, nr),
+				   create, NULL, bhp);
+}
+
+static struct nilfs_palloc_group_desc *
+nilfs_palloc_block_get_group_desc(const struct inode *inode,
+				  unsigned long group,
+				  const struct buffer_head *bh, void *kaddr)
+{
+	return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +
+		group % nilfs_palloc_groups_per_desc_block(inode);
+}
+
+static unsigned char *
+nilfs_palloc_block_get_bitmap(const struct inode *inode,
+			      const struct buffer_head *bh, void *kaddr)
+{
+	return (unsigned char *)(kaddr + bh_offset(bh));
+}
+
+void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,
+				   const struct buffer_head *bh, void *kaddr)
+{
+	unsigned long entry_offset, group_offset;
+
+	nilfs_palloc_group(inode, nr, &group_offset);
+	entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;
+
+	return kaddr + bh_offset(bh) +
+		entry_offset * NILFS_MDT(inode)->mi_entry_size;
+}
+
+static int nilfs_palloc_find_available_slot(struct inode *inode,
+					    unsigned long group,
+					    unsigned long target,
+					    unsigned char *bitmap,
+					    int bsize)  /* size in bits */
+{
+	int curr, pos, end, i;
+
+	if (target > 0) {
+		end = (target + BITS_PER_LONG - 1) & ~(BITS_PER_LONG - 1);
+		if (end > bsize)
+			end = bsize;
+		pos = nilfs_find_next_zero_bit(bitmap, end, target);
+		if (pos < end &&
+		    !nilfs_set_bit_atomic(
+			    nilfs_mdt_bgl_lock(inode, group), pos, bitmap))
+			return pos;
+	} else
+		end = 0;
+
+	for (i = 0, curr = end;
+	     i < bsize;
+	     i += BITS_PER_LONG, curr += BITS_PER_LONG) {
+		/* wrap around */
+		if (curr >= bsize)
+			curr = 0;
+		while (*((unsigned long *)bitmap + curr / BITS_PER_LONG)
+		       != ~0UL) {
+			end = curr + BITS_PER_LONG;
+			if (end > bsize)
+				end = bsize;
+			pos = nilfs_find_next_zero_bit(bitmap, end, curr);
+			if ((pos < end) &&
+			    !nilfs_set_bit_atomic(
+				    nilfs_mdt_bgl_lock(inode, group), pos,
+				    bitmap))
+				return pos;
+		}
+	}
+	return -ENOSPC;
+}
+
+static unsigned long
+nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
+				       unsigned long curr, unsigned long max)
+{
+	return min_t(unsigned long,
+		     nilfs_palloc_groups_per_desc_block(inode) -
+		     curr % nilfs_palloc_groups_per_desc_block(inode),
+		     max - curr + 1);
+}
+
+int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
+				     struct nilfs_palloc_req *req)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	struct nilfs_palloc_group_desc *desc;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned long group, maxgroup, ngroups;
+	unsigned long group_offset, maxgroup_offset;
+	unsigned long n, entries_per_group, groups_per_desc_block;
+	unsigned long i, j;
+	int pos, ret;
+
+	ngroups = nilfs_palloc_groups_count(inode);
+	maxgroup = ngroups - 1;
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	entries_per_group = nilfs_palloc_entries_per_group(inode);
+	groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);
+
+	for (i = 0; i < ngroups; i += n) {
+		if (group >= ngroups) {
+			/* wrap around */
+			group = 0;
+			maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr,
+						      &maxgroup_offset) - 1;
+		}
+		ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
+		if (ret < 0)
+			return ret;
+		desc_kaddr = kmap(desc_bh->b_page);
+		desc = nilfs_palloc_block_get_group_desc(
+			inode, group, desc_bh, desc_kaddr);
+		n = nilfs_palloc_rest_groups_in_desc_block(inode, group,
+							   maxgroup);
+		for (j = 0; j < n; j++, desc++, group++) {
+			if (nilfs_palloc_group_desc_nfrees(inode, group, desc)
+			    > 0) {
+				ret = nilfs_palloc_get_bitmap_block(
+					inode, group, 1, &bitmap_bh);
+				if (ret < 0)
+					goto out_desc;
+				bitmap_kaddr = kmap(bitmap_bh->b_page);
+				bitmap = nilfs_palloc_block_get_bitmap(
+					inode, bitmap_bh, bitmap_kaddr);
+				pos = nilfs_palloc_find_available_slot(
+					inode, group, group_offset, bitmap,
+					entries_per_group);
+				if (pos >= 0) {
+					/* found a free entry */
+					nilfs_palloc_group_desc_add_entries(
+						inode, group, desc, -1);
+					req->pr_entry_nr =
+						entries_per_group * group + pos;
+					kunmap(desc_bh->b_page);
+					kunmap(bitmap_bh->b_page);
+
+					req->pr_desc_bh = desc_bh;
+					req->pr_bitmap_bh = bitmap_bh;
+					return 0;
+				}
+				kunmap(bitmap_bh->b_page);
+				brelse(bitmap_bh);
+			}
+
+			group_offset = 0;
+		}
+
+		kunmap(desc_bh->b_page);
+		brelse(desc_bh);
+	}
+
+	/* no entries left */
+	return -ENOSPC;
+
+ out_desc:
+	kunmap(desc_bh->b_page);
+	brelse(desc_bh);
+	return ret;
+}
+
+void nilfs_palloc_commit_alloc_entry(struct inode *inode,
+				     struct nilfs_palloc_req *req)
+{
+	nilfs_mdt_mark_buffer_dirty(req->pr_bitmap_bh);
+	nilfs_mdt_mark_buffer_dirty(req->pr_desc_bh);
+	nilfs_mdt_mark_dirty(inode);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+}
+
+void nilfs_palloc_commit_free_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct nilfs_palloc_group_desc *desc;
+	unsigned long group, group_offset;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	desc_kaddr = kmap(req->pr_desc_bh->b_page);
+	desc = nilfs_palloc_block_get_group_desc(inode, group,
+						 req->pr_desc_bh, desc_kaddr);
+	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
+	bitmap = nilfs_palloc_block_get_bitmap(inode, req->pr_bitmap_bh,
+					       bitmap_kaddr);
+
+	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),
+				    group_offset, bitmap))
+		printk(KERN_WARNING "%s: entry number %llu already freed\n",
+		       __func__, (unsigned long long)req->pr_entry_nr);
+
+	nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);
+
+	kunmap(req->pr_bitmap_bh->b_page);
+	kunmap(req->pr_desc_bh->b_page);
+
+	nilfs_mdt_mark_buffer_dirty(req->pr_desc_bh);
+	nilfs_mdt_mark_buffer_dirty(req->pr_bitmap_bh);
+	nilfs_mdt_mark_dirty(inode);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+}
+
+void nilfs_palloc_abort_alloc_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct nilfs_palloc_group_desc *desc;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned char *bitmap;
+	unsigned long group, group_offset;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	desc_kaddr = kmap(req->pr_desc_bh->b_page);
+	desc = nilfs_palloc_block_get_group_desc(inode, group,
+						 req->pr_desc_bh, desc_kaddr);
+	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
+	bitmap = nilfs_palloc_block_get_bitmap(inode, req->pr_bitmap_bh,
+					       bitmap_kaddr);
+	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),
+				    group_offset, bitmap))
+		printk(KERN_WARNING "%s: entry numer %llu already freed\n",
+		       __func__, (unsigned long long)req->pr_entry_nr);
+
+	nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);
+
+	kunmap(req->pr_bitmap_bh->b_page);
+	kunmap(req->pr_desc_bh->b_page);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+
+	req->pr_entry_nr = 0;
+	req->pr_bitmap_bh = NULL;
+	req->pr_desc_bh = NULL;
+}
+
+int nilfs_palloc_prepare_free_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	unsigned long group, group_offset;
+	int ret;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
+	if (ret < 0)
+		return ret;
+	ret = nilfs_palloc_get_bitmap_block(inode, group, 1, &bitmap_bh);
+	if (ret < 0) {
+		brelse(desc_bh);
+		return ret;
+	}
+
+	req->pr_desc_bh = desc_bh;
+	req->pr_bitmap_bh = bitmap_bh;
+	return 0;
+}
+
+void nilfs_palloc_abort_free_entry(struct inode *inode,
+				   struct nilfs_palloc_req *req)
+{
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+
+	req->pr_entry_nr = 0;
+	req->pr_bitmap_bh = NULL;
+	req->pr_desc_bh = NULL;
+}
+
+static int
+nilfs_palloc_group_is_in(struct inode *inode, unsigned long group, __u64 nr)
+{
+	__u64 first, last;
+
+	first = group * nilfs_palloc_entries_per_group(inode);
+	last = first + nilfs_palloc_entries_per_group(inode) - 1;
+	return (nr >= first) && (nr <= last);
+}
+
+int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	struct nilfs_palloc_group_desc *desc;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned long group, group_offset;
+	int i, j, n, ret;
+
+	for (i = 0; i < nitems; i += n) {
+		group = nilfs_palloc_group(inode, entry_nrs[i], &group_offset);
+		ret = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
+		if (ret < 0)
+			return ret;
+		ret = nilfs_palloc_get_bitmap_block(inode, group, 0,
+						    &bitmap_bh);
+		if (ret < 0) {
+			brelse(desc_bh);
+			return ret;
+		}
+		desc_kaddr = kmap(desc_bh->b_page);
+		desc = nilfs_palloc_block_get_group_desc(
+			inode, group, desc_bh, desc_kaddr);
+		bitmap_kaddr = kmap(bitmap_bh->b_page);
+		bitmap = nilfs_palloc_block_get_bitmap(
+			inode, bitmap_bh, bitmap_kaddr);
+		for (j = i, n = 0;
+		     (j < nitems) && nilfs_palloc_group_is_in(inode, group,
+							      entry_nrs[j]);
+		     j++, n++) {
+			nilfs_palloc_group(inode, entry_nrs[j], &group_offset);
+			if (!nilfs_clear_bit_atomic(
+				    nilfs_mdt_bgl_lock(inode, group),
+				    group_offset, bitmap)) {
+				printk(KERN_WARNING
+				       "%s: entry number %llu already freed\n",
+				       __func__,
+				       (unsigned long long)entry_nrs[j]);
+			}
+		}
+		nilfs_palloc_group_desc_add_entries(inode, group, desc, n);
+
+		kunmap(bitmap_bh->b_page);
+		kunmap(desc_bh->b_page);
+
+		nilfs_mdt_mark_buffer_dirty(desc_bh);
+		nilfs_mdt_mark_buffer_dirty(bitmap_bh);
+		nilfs_mdt_mark_dirty(inode);
+
+		brelse(bitmap_bh);
+		brelse(desc_bh);
+	}
+	return 0;
+}
diff --git a/fs/nilfs2/alloc.h b/fs/nilfs2/alloc.h
new file mode 100644
index 00000000000..4ace5475c2c
--- /dev/null
+++ b/fs/nilfs2/alloc.h
@@ -0,0 +1,72 @@
+/*
+ * alloc.h - persistent object (dat entry/disk inode) allocator/deallocator
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Original code was written by Koji Sato <koji@osrg.net>.
+ * Two allocators were unified by Ryusuke Konishi <ryusuke@osrg.net>,
+ *                                Amagai Yoshiji <amagai@osrg.net>.
+ */
+
+#ifndef _NILFS_ALLOC_H
+#define _NILFS_ALLOC_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+
+static inline unsigned long
+nilfs_palloc_entries_per_group(const struct inode *inode)
+{
+	return 1UL << (inode->i_blkbits + 3 /* log2(8 = CHAR_BITS) */);
+}
+
+int nilfs_palloc_init_blockgroup(struct inode *, unsigned);
+int nilfs_palloc_get_entry_block(struct inode *, __u64, int,
+				 struct buffer_head **);
+void *nilfs_palloc_block_get_entry(const struct inode *, __u64,
+				   const struct buffer_head *, void *);
+
+/**
+ * nilfs_palloc_req - persistent alloctor request and reply
+ * @pr_entry_nr: entry number (vblocknr or inode number)
+ * @pr_desc_bh: buffer head of the buffer containing block group descriptors
+ * @pr_bitmap_bh: buffer head of the buffer containing a block group bitmap
+ * @pr_entry_bh: buffer head of the buffer containing translation entries
+ */
+struct nilfs_palloc_req {
+	__u64 pr_entry_nr;
+	struct buffer_head *pr_desc_bh;
+	struct buffer_head *pr_bitmap_bh;
+	struct buffer_head *pr_entry_bh;
+};
+
+int nilfs_palloc_prepare_alloc_entry(struct inode *,
+				     struct nilfs_palloc_req *);
+void nilfs_palloc_commit_alloc_entry(struct inode *,
+				     struct nilfs_palloc_req *);
+void nilfs_palloc_abort_alloc_entry(struct inode *, struct nilfs_palloc_req *);
+void nilfs_palloc_commit_free_entry(struct inode *, struct nilfs_palloc_req *);
+int nilfs_palloc_prepare_free_entry(struct inode *, struct nilfs_palloc_req *);
+void nilfs_palloc_abort_free_entry(struct inode *, struct nilfs_palloc_req *);
+int nilfs_palloc_freev(struct inode *, __u64 *, size_t);
+
+#define nilfs_set_bit_atomic		ext2_set_bit_atomic
+#define nilfs_clear_bit_atomic		ext2_clear_bit_atomic
+#define nilfs_find_next_zero_bit	ext2_find_next_zero_bit
+
+#endif	/* _NILFS_ALLOC_H */
diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
new file mode 100644
index 00000000000..24638e059bf
--- /dev/null
+++ b/fs/nilfs2/bmap.c
@@ -0,0 +1,783 @@
+/*
+ * bmap.c - NILFS block mapping.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include "nilfs.h"
+#include "bmap.h"
+#include "sb.h"
+#include "btnode.h"
+#include "mdt.h"
+#include "dat.h"
+#include "alloc.h"
+
+int nilfs_bmap_lookup_at_level(struct nilfs_bmap *bmap, __u64 key, int level,
+			       __u64 *ptrp)
+{
+	__u64 ptr;
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_lookup(bmap, key, level, ptrp);
+	if (ret < 0)
+		goto out;
+	if (bmap->b_pops->bpop_translate != NULL) {
+		ret = bmap->b_pops->bpop_translate(bmap, *ptrp, &ptr);
+		if (ret < 0)
+			goto out;
+		*ptrp = ptr;
+	}
+
+ out:
+	up_read(&bmap->b_sem);
+	return ret;
+}
+
+
+/**
+ * nilfs_bmap_lookup - find a record
+ * @bmap: bmap
+ * @key: key
+ * @recp: pointer to record
+ *
+ * Description: nilfs_bmap_lookup() finds a record whose key matches @key in
+ * @bmap.
+ *
+ * Return Value: On success, 0 is returned and the record associated with @key
+ * is stored in the place pointed by @recp. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - A record associated with @key does not exist.
+ */
+int nilfs_bmap_lookup(struct nilfs_bmap *bmap,
+		      unsigned long key,
+		      unsigned long *recp)
+{
+	__u64 ptr;
+	int ret;
+
+	/* XXX: use macro for level 1 */
+	ret = nilfs_bmap_lookup_at_level(bmap, key, 1, &ptr);
+	if (recp != NULL)
+		*recp = ptr;
+	return ret;
+}
+
+static int nilfs_bmap_do_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
+{
+	__u64 keys[NILFS_BMAP_SMALL_HIGH + 1];
+	__u64 ptrs[NILFS_BMAP_SMALL_HIGH + 1];
+	int ret, n;
+
+	if (bmap->b_ops->bop_check_insert != NULL) {
+		ret = bmap->b_ops->bop_check_insert(bmap, key);
+		if (ret > 0) {
+			n = bmap->b_ops->bop_gather_data(
+				bmap, keys, ptrs, NILFS_BMAP_SMALL_HIGH + 1);
+			if (n < 0)
+				return n;
+			ret = nilfs_btree_convert_and_insert(
+				bmap, key, ptr, keys, ptrs, n,
+				NILFS_BMAP_LARGE_LOW, NILFS_BMAP_LARGE_HIGH);
+			if (ret == 0)
+				bmap->b_u.u_flags |= NILFS_BMAP_LARGE;
+
+			return ret;
+		} else if (ret < 0)
+			return ret;
+	}
+
+	return bmap->b_ops->bop_insert(bmap, key, ptr);
+}
+
+/**
+ * nilfs_bmap_insert - insert a new key-record pair into a bmap
+ * @bmap: bmap
+ * @key: key
+ * @rec: record
+ *
+ * Description: nilfs_bmap_insert() inserts the new key-record pair specified
+ * by @key and @rec into @bmap.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EEXIST - A record associated with @key already exist.
+ */
+int nilfs_bmap_insert(struct nilfs_bmap *bmap,
+		      unsigned long key,
+		      unsigned long rec)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_insert(bmap, key, rec);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+static int nilfs_bmap_do_delete(struct nilfs_bmap *bmap, __u64 key)
+{
+	__u64 keys[NILFS_BMAP_LARGE_LOW + 1];
+	__u64 ptrs[NILFS_BMAP_LARGE_LOW + 1];
+	int ret, n;
+
+	if (bmap->b_ops->bop_check_delete != NULL) {
+		ret = bmap->b_ops->bop_check_delete(bmap, key);
+		if (ret > 0) {
+			n = bmap->b_ops->bop_gather_data(
+				bmap, keys, ptrs, NILFS_BMAP_LARGE_LOW + 1);
+			if (n < 0)
+				return n;
+			ret = nilfs_direct_delete_and_convert(
+				bmap, key, keys, ptrs, n,
+				NILFS_BMAP_SMALL_LOW, NILFS_BMAP_SMALL_HIGH);
+			if (ret == 0)
+				bmap->b_u.u_flags &= ~NILFS_BMAP_LARGE;
+
+			return ret;
+		} else if (ret < 0)
+			return ret;
+	}
+
+	return bmap->b_ops->bop_delete(bmap, key);
+}
+
+int nilfs_bmap_last_key(struct nilfs_bmap *bmap, unsigned long *key)
+{
+	__u64 lastkey;
+	int ret;
+
+	down_read(&bmap->b_sem);
+	ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
+	if (!ret)
+		*key = lastkey;
+	up_read(&bmap->b_sem);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_delete - delete a key-record pair from a bmap
+ * @bmap: bmap
+ * @key: key
+ *
+ * Description: nilfs_bmap_delete() deletes the key-record pair specified by
+ * @key from @bmap.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - A record associated with @key does not exist.
+ */
+int nilfs_bmap_delete(struct nilfs_bmap *bmap, unsigned long key)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_delete(bmap, key);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+static int nilfs_bmap_do_truncate(struct nilfs_bmap *bmap, unsigned long key)
+{
+	__u64 lastkey;
+	int ret;
+
+	ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
+	if (ret < 0) {
+		if (ret == -ENOENT)
+			ret = 0;
+		return ret;
+	}
+
+	while (key <= lastkey) {
+		ret = nilfs_bmap_do_delete(bmap, lastkey);
+		if (ret < 0)
+			return ret;
+		ret = bmap->b_ops->bop_last_key(bmap, &lastkey);
+		if (ret < 0) {
+			if (ret == -ENOENT)
+				ret = 0;
+			return ret;
+		}
+	}
+	return 0;
+}
+
+/**
+ * nilfs_bmap_truncate - truncate a bmap to a specified key
+ * @bmap: bmap
+ * @key: key
+ *
+ * Description: nilfs_bmap_truncate() removes key-record pairs whose keys are
+ * greater than or equal to @key from @bmap.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_bmap_truncate(struct nilfs_bmap *bmap, unsigned long key)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_do_truncate(bmap, key);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_clear - free resources a bmap holds
+ * @bmap: bmap
+ *
+ * Description: nilfs_bmap_clear() frees resources associated with @bmap.
+ */
+void nilfs_bmap_clear(struct nilfs_bmap *bmap)
+{
+	down_write(&bmap->b_sem);
+	if (bmap->b_ops->bop_clear != NULL)
+		bmap->b_ops->bop_clear(bmap);
+	up_write(&bmap->b_sem);
+}
+
+/**
+ * nilfs_bmap_propagate - propagate dirty state
+ * @bmap: bmap
+ * @bh: buffer head
+ *
+ * Description: nilfs_bmap_propagate() marks the buffers that directly or
+ * indirectly refer to the block specified by @bh dirty.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_bmap_propagate(struct nilfs_bmap *bmap, struct buffer_head *bh)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_propagate(bmap, bh);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_lookup_dirty_buffers -
+ * @bmap: bmap
+ * @listp: pointer to buffer head list
+ */
+void nilfs_bmap_lookup_dirty_buffers(struct nilfs_bmap *bmap,
+				     struct list_head *listp)
+{
+	if (bmap->b_ops->bop_lookup_dirty_buffers != NULL)
+		bmap->b_ops->bop_lookup_dirty_buffers(bmap, listp);
+}
+
+/**
+ * nilfs_bmap_assign - assign a new block number to a block
+ * @bmap: bmap
+ * @bhp: pointer to buffer head
+ * @blocknr: block number
+ * @binfo: block information
+ *
+ * Description: nilfs_bmap_assign() assigns the block number @blocknr to the
+ * buffer specified by @bh.
+ *
+ * Return Value: On success, 0 is returned and the buffer head of a newly
+ * create buffer and the block information associated with the buffer are
+ * stored in the place pointed by @bh and @binfo, respectively. On error, one
+ * of the following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_bmap_assign(struct nilfs_bmap *bmap,
+		      struct buffer_head **bh,
+		      unsigned long blocknr,
+		      union nilfs_binfo *binfo)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_assign(bmap, bh, blocknr, binfo);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_mark - mark block dirty
+ * @bmap: bmap
+ * @key: key
+ * @level: level
+ *
+ * Description: nilfs_bmap_mark() marks the block specified by @key and @level
+ * as dirty.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_bmap_mark(struct nilfs_bmap *bmap, __u64 key, int level)
+{
+	int ret;
+
+	if (bmap->b_ops->bop_mark == NULL)
+		return 0;
+
+	down_write(&bmap->b_sem);
+	ret = bmap->b_ops->bop_mark(bmap, key, level);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+/**
+ * nilfs_bmap_test_and_clear_dirty - test and clear a bmap dirty state
+ * @bmap: bmap
+ *
+ * Description: nilfs_test_and_clear() is the atomic operation to test and
+ * clear the dirty state of @bmap.
+ *
+ * Return Value: 1 is returned if @bmap is dirty, or 0 if clear.
+ */
+int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *bmap)
+{
+	int ret;
+
+	down_write(&bmap->b_sem);
+	ret = nilfs_bmap_dirty(bmap);
+	nilfs_bmap_clear_dirty(bmap);
+	up_write(&bmap->b_sem);
+	return ret;
+}
+
+
+/*
+ * Internal use only
+ */
+
+void nilfs_bmap_add_blocks(const struct nilfs_bmap *bmap, int n)
+{
+	inode_add_bytes(bmap->b_inode, (1 << bmap->b_inode->i_blkbits) * n);
+	if (NILFS_MDT(bmap->b_inode))
+		nilfs_mdt_mark_dirty(bmap->b_inode);
+	else
+		mark_inode_dirty(bmap->b_inode);
+}
+
+void nilfs_bmap_sub_blocks(const struct nilfs_bmap *bmap, int n)
+{
+	inode_sub_bytes(bmap->b_inode, (1 << bmap->b_inode->i_blkbits) * n);
+	if (NILFS_MDT(bmap->b_inode))
+		nilfs_mdt_mark_dirty(bmap->b_inode);
+	else
+		mark_inode_dirty(bmap->b_inode);
+}
+
+int nilfs_bmap_get_block(const struct nilfs_bmap *bmap, __u64 ptr,
+			 struct buffer_head **bhp)
+{
+	return nilfs_btnode_get(&NILFS_BMAP_I(bmap)->i_btnode_cache,
+				ptr, 0, bhp, 0);
+}
+
+void nilfs_bmap_put_block(const struct nilfs_bmap *bmap,
+			  struct buffer_head *bh)
+{
+	brelse(bh);
+}
+
+int nilfs_bmap_get_new_block(const struct nilfs_bmap *bmap, __u64 ptr,
+			     struct buffer_head **bhp)
+{
+	int ret;
+
+	ret = nilfs_btnode_get(&NILFS_BMAP_I(bmap)->i_btnode_cache,
+			       ptr, 0, bhp, 1);
+	if (ret < 0)
+		return ret;
+	set_buffer_nilfs_volatile(*bhp);
+	return 0;
+}
+
+void nilfs_bmap_delete_block(const struct nilfs_bmap *bmap,
+			     struct buffer_head *bh)
+{
+	nilfs_btnode_delete(bh);
+}
+
+__u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *bmap,
+			      const struct buffer_head *bh)
+{
+	struct buffer_head *pbh;
+	__u64 key;
+
+	key = page_index(bh->b_page) << (PAGE_CACHE_SHIFT -
+					 bmap->b_inode->i_blkbits);
+	for (pbh = page_buffers(bh->b_page); pbh != bh;
+	     pbh = pbh->b_this_page, key++);
+
+	return key;
+}
+
+__u64 nilfs_bmap_find_target_seq(const struct nilfs_bmap *bmap, __u64 key)
+{
+	__s64 diff;
+
+	diff = key - bmap->b_last_allocated_key;
+	if ((nilfs_bmap_keydiff_abs(diff) < NILFS_INODE_BMAP_SIZE) &&
+	    (bmap->b_last_allocated_ptr != NILFS_BMAP_INVALID_PTR) &&
+	    (bmap->b_last_allocated_ptr + diff > 0))
+		return bmap->b_last_allocated_ptr + diff;
+	else
+		return NILFS_BMAP_INVALID_PTR;
+}
+
+static struct inode *nilfs_bmap_get_dat(const struct nilfs_bmap *bmap)
+{
+	return nilfs_dat_inode(NILFS_I_NILFS(bmap->b_inode));
+}
+
+#define NILFS_BMAP_GROUP_DIV	8
+__u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
+{
+	struct inode *dat = nilfs_bmap_get_dat(bmap);
+	unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
+	unsigned long group = bmap->b_inode->i_ino / entries_per_group;
+
+	return group * entries_per_group +
+		(bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
+		(entries_per_group / NILFS_BMAP_GROUP_DIV);
+}
+
+static int nilfs_bmap_prepare_alloc_v(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req)
+{
+	return nilfs_dat_prepare_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static void nilfs_bmap_commit_alloc_v(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_commit_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static void nilfs_bmap_abort_alloc_v(struct nilfs_bmap *bmap,
+				     union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_abort_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static int nilfs_bmap_prepare_start_v(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req)
+{
+	return nilfs_dat_prepare_start(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static void nilfs_bmap_commit_start_v(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req,
+				      sector_t blocknr)
+{
+	nilfs_dat_commit_start(nilfs_bmap_get_dat(bmap), &req->bpr_req,
+			       blocknr);
+}
+
+static void nilfs_bmap_abort_start_v(struct nilfs_bmap *bmap,
+				     union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_abort_start(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static int nilfs_bmap_prepare_end_v(struct nilfs_bmap *bmap,
+				    union nilfs_bmap_ptr_req *req)
+{
+	return nilfs_dat_prepare_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+static void nilfs_bmap_commit_end_v(struct nilfs_bmap *bmap,
+				    union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_commit_end(nilfs_bmap_get_dat(bmap), &req->bpr_req, 0);
+}
+
+static void nilfs_bmap_commit_end_vmdt(struct nilfs_bmap *bmap,
+				       union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_commit_end(nilfs_bmap_get_dat(bmap), &req->bpr_req, 1);
+}
+
+static void nilfs_bmap_abort_end_v(struct nilfs_bmap *bmap,
+				   union nilfs_bmap_ptr_req *req)
+{
+	nilfs_dat_abort_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
+}
+
+int nilfs_bmap_move_v(const struct nilfs_bmap *bmap, __u64 vblocknr,
+		      sector_t blocknr)
+{
+	return nilfs_dat_move(nilfs_bmap_get_dat(bmap), vblocknr, blocknr);
+}
+
+int nilfs_bmap_mark_dirty(const struct nilfs_bmap *bmap, __u64 vblocknr)
+{
+	return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(bmap), vblocknr);
+}
+
+int nilfs_bmap_prepare_update(struct nilfs_bmap *bmap,
+			      union nilfs_bmap_ptr_req *oldreq,
+			      union nilfs_bmap_ptr_req *newreq)
+{
+	int ret;
+
+	ret = bmap->b_pops->bpop_prepare_end_ptr(bmap, oldreq);
+	if (ret < 0)
+		return ret;
+	ret = bmap->b_pops->bpop_prepare_alloc_ptr(bmap, newreq);
+	if (ret < 0)
+		bmap->b_pops->bpop_abort_end_ptr(bmap, oldreq);
+
+	return ret;
+}
+
+void nilfs_bmap_commit_update(struct nilfs_bmap *bmap,
+			      union nilfs_bmap_ptr_req *oldreq,
+			      union nilfs_bmap_ptr_req *newreq)
+{
+	bmap->b_pops->bpop_commit_end_ptr(bmap, oldreq);
+	bmap->b_pops->bpop_commit_alloc_ptr(bmap, newreq);
+}
+
+void nilfs_bmap_abort_update(struct nilfs_bmap *bmap,
+			     union nilfs_bmap_ptr_req *oldreq,
+			     union nilfs_bmap_ptr_req *newreq)
+{
+	bmap->b_pops->bpop_abort_end_ptr(bmap, oldreq);
+	bmap->b_pops->bpop_abort_alloc_ptr(bmap, newreq);
+}
+
+static int nilfs_bmap_translate_v(const struct nilfs_bmap *bmap, __u64 ptr,
+				  __u64 *ptrp)
+{
+	sector_t blocknr;
+	int ret;
+
+	ret = nilfs_dat_translate(nilfs_bmap_get_dat(bmap), ptr, &blocknr);
+	if (ret < 0)
+		return ret;
+	if (ptrp != NULL)
+		*ptrp = blocknr;
+	return 0;
+}
+
+static int nilfs_bmap_prepare_alloc_p(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req)
+{
+	/* ignore target ptr */
+	req->bpr_ptr = bmap->b_last_allocated_ptr++;
+	return 0;
+}
+
+static void nilfs_bmap_commit_alloc_p(struct nilfs_bmap *bmap,
+				      union nilfs_bmap_ptr_req *req)
+{
+	/* do nothing */
+}
+
+static void nilfs_bmap_abort_alloc_p(struct nilfs_bmap *bmap,
+				     union nilfs_bmap_ptr_req *req)
+{
+	bmap->b_last_allocated_ptr--;
+}
+
+static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_v = {
+	.bpop_prepare_alloc_ptr	=	nilfs_bmap_prepare_alloc_v,
+	.bpop_commit_alloc_ptr	=	nilfs_bmap_commit_alloc_v,
+	.bpop_abort_alloc_ptr	=	nilfs_bmap_abort_alloc_v,
+	.bpop_prepare_start_ptr	=	nilfs_bmap_prepare_start_v,
+	.bpop_commit_start_ptr	=	nilfs_bmap_commit_start_v,
+	.bpop_abort_start_ptr	=	nilfs_bmap_abort_start_v,
+	.bpop_prepare_end_ptr	=	nilfs_bmap_prepare_end_v,
+	.bpop_commit_end_ptr	=	nilfs_bmap_commit_end_v,
+	.bpop_abort_end_ptr	=	nilfs_bmap_abort_end_v,
+
+	.bpop_translate		=	nilfs_bmap_translate_v,
+};
+
+static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_vmdt = {
+	.bpop_prepare_alloc_ptr	=	nilfs_bmap_prepare_alloc_v,
+	.bpop_commit_alloc_ptr	=	nilfs_bmap_commit_alloc_v,
+	.bpop_abort_alloc_ptr	=	nilfs_bmap_abort_alloc_v,
+	.bpop_prepare_start_ptr	=	nilfs_bmap_prepare_start_v,
+	.bpop_commit_start_ptr	=	nilfs_bmap_commit_start_v,
+	.bpop_abort_start_ptr	=	nilfs_bmap_abort_start_v,
+	.bpop_prepare_end_ptr	=	nilfs_bmap_prepare_end_v,
+	.bpop_commit_end_ptr	=	nilfs_bmap_commit_end_vmdt,
+	.bpop_abort_end_ptr	=	nilfs_bmap_abort_end_v,
+
+	.bpop_translate		=	nilfs_bmap_translate_v,
+};
+
+static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_p = {
+	.bpop_prepare_alloc_ptr	=	nilfs_bmap_prepare_alloc_p,
+	.bpop_commit_alloc_ptr	=	nilfs_bmap_commit_alloc_p,
+	.bpop_abort_alloc_ptr	=	nilfs_bmap_abort_alloc_p,
+	.bpop_prepare_start_ptr	=	NULL,
+	.bpop_commit_start_ptr	=	NULL,
+	.bpop_abort_start_ptr	=	NULL,
+	.bpop_prepare_end_ptr	=	NULL,
+	.bpop_commit_end_ptr	=	NULL,
+	.bpop_abort_end_ptr	=	NULL,
+
+	.bpop_translate		=	NULL,
+};
+
+static const struct nilfs_bmap_ptr_operations nilfs_bmap_ptr_ops_gc = {
+	.bpop_prepare_alloc_ptr	=	NULL,
+	.bpop_commit_alloc_ptr	=	NULL,
+	.bpop_abort_alloc_ptr	=	NULL,
+	.bpop_prepare_start_ptr	=	NULL,
+	.bpop_commit_start_ptr	=	NULL,
+	.bpop_abort_start_ptr	=	NULL,
+	.bpop_prepare_end_ptr	=	NULL,
+	.bpop_commit_end_ptr	=	NULL,
+	.bpop_abort_end_ptr	=	NULL,
+
+	.bpop_translate		=	NULL,
+};
+
+/**
+ * nilfs_bmap_read - read a bmap from an inode
+ * @bmap: bmap
+ * @raw_inode: on-disk inode
+ *
+ * Description: nilfs_bmap_read() initializes the bmap @bmap.
+ *
+ * Return Value: On success, 0 is returned. On error, the following negative
+ * error code is returned.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_bmap_read(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
+{
+	if (raw_inode == NULL)
+		memset(bmap->b_u.u_data, 0, NILFS_BMAP_SIZE);
+	else
+		memcpy(bmap->b_u.u_data, raw_inode->i_bmap, NILFS_BMAP_SIZE);
+
+	init_rwsem(&bmap->b_sem);
+	bmap->b_state = 0;
+	bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
+	switch (bmap->b_inode->i_ino) {
+	case NILFS_DAT_INO:
+		bmap->b_pops = &nilfs_bmap_ptr_ops_p;
+		bmap->b_last_allocated_key = 0;	/* XXX: use macro */
+		bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;
+		break;
+	case NILFS_CPFILE_INO:
+	case NILFS_SUFILE_INO:
+		bmap->b_pops = &nilfs_bmap_ptr_ops_vmdt;
+		bmap->b_last_allocated_key = 0;	/* XXX: use macro */
+		bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+		break;
+	default:
+		bmap->b_pops = &nilfs_bmap_ptr_ops_v;
+		bmap->b_last_allocated_key = 0;	/* XXX: use macro */
+		bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+		break;
+	}
+
+	return (bmap->b_u.u_flags & NILFS_BMAP_LARGE) ?
+		nilfs_btree_init(bmap,
+				 NILFS_BMAP_LARGE_LOW,
+				 NILFS_BMAP_LARGE_HIGH) :
+		nilfs_direct_init(bmap,
+				  NILFS_BMAP_SMALL_LOW,
+				  NILFS_BMAP_SMALL_HIGH);
+}
+
+/**
+ * nilfs_bmap_write - write back a bmap to an inode
+ * @bmap: bmap
+ * @raw_inode: on-disk inode
+ *
+ * Description: nilfs_bmap_write() stores @bmap in @raw_inode.
+ */
+void nilfs_bmap_write(struct nilfs_bmap *bmap, struct nilfs_inode *raw_inode)
+{
+	down_write(&bmap->b_sem);
+	memcpy(raw_inode->i_bmap, bmap->b_u.u_data,
+	       NILFS_INODE_BMAP_SIZE * sizeof(__le64));
+	if (bmap->b_inode->i_ino == NILFS_DAT_INO)
+		bmap->b_last_allocated_ptr = NILFS_BMAP_NEW_PTR_INIT;
+
+	up_write(&bmap->b_sem);
+}
+
+void nilfs_bmap_init_gc(struct nilfs_bmap *bmap)
+{
+	memset(&bmap->b_u, 0, NILFS_BMAP_SIZE);
+	init_rwsem(&bmap->b_sem);
+	bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
+	bmap->b_pops = &nilfs_bmap_ptr_ops_gc;
+	bmap->b_last_allocated_key = 0;
+	bmap->b_last_allocated_ptr = NILFS_BMAP_INVALID_PTR;
+	bmap->b_state = 0;
+	nilfs_btree_init_gc(bmap);
+}
+
+void nilfs_bmap_init_gcdat(struct nilfs_bmap *gcbmap, struct nilfs_bmap *bmap)
+{
+	memcpy(gcbmap, bmap, sizeof(union nilfs_bmap_union));
+	init_rwsem(&gcbmap->b_sem);
+	gcbmap->b_inode = &NILFS_BMAP_I(gcbmap)->vfs_inode;
+}
+
+void nilfs_bmap_commit_gcdat(struct nilfs_bmap *gcbmap, struct nilfs_bmap *bmap)
+{
+	memcpy(bmap, gcbmap, sizeof(union nilfs_bmap_union));
+	init_rwsem(&bmap->b_sem);
+	bmap->b_inode = &NILFS_BMAP_I(bmap)->vfs_inode;
+}
diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
new file mode 100644
index 00000000000..4f2708abb1b
--- /dev/null
+++ b/fs/nilfs2/bmap.h
@@ -0,0 +1,244 @@
+/*
+ * bmap.h - NILFS block mapping.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_BMAP_H
+#define _NILFS_BMAP_H
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+#include "alloc.h"
+
+#define NILFS_BMAP_INVALID_PTR	0
+
+#define nilfs_bmap_dkey_to_key(dkey)	le64_to_cpu(dkey)
+#define nilfs_bmap_key_to_dkey(key)	cpu_to_le64(key)
+#define nilfs_bmap_dptr_to_ptr(dptr)	le64_to_cpu(dptr)
+#define nilfs_bmap_ptr_to_dptr(ptr)	cpu_to_le64(ptr)
+
+#define nilfs_bmap_keydiff_abs(diff)	((diff) < 0 ? -(diff) : (diff))
+
+
+struct nilfs_bmap;
+
+/**
+ * union nilfs_bmap_ptr_req - request for bmap ptr
+ * @bpr_ptr: bmap pointer
+ * @bpr_req: request for persistent allocator
+ */
+union nilfs_bmap_ptr_req {
+	__u64 bpr_ptr;
+	struct nilfs_palloc_req bpr_req;
+};
+
+/**
+ * struct nilfs_bmap_stats - bmap statistics
+ * @bs_nblocks: number of blocks created or deleted
+ */
+struct nilfs_bmap_stats {
+	unsigned int bs_nblocks;
+};
+
+/**
+ * struct nilfs_bmap_operations - bmap operation table
+ */
+struct nilfs_bmap_operations {
+	int (*bop_lookup)(const struct nilfs_bmap *, __u64, int, __u64 *);
+	int (*bop_insert)(struct nilfs_bmap *, __u64, __u64);
+	int (*bop_delete)(struct nilfs_bmap *, __u64);
+	void (*bop_clear)(struct nilfs_bmap *);
+
+	int (*bop_propagate)(const struct nilfs_bmap *, struct buffer_head *);
+	void (*bop_lookup_dirty_buffers)(struct nilfs_bmap *,
+					 struct list_head *);
+
+	int (*bop_assign)(struct nilfs_bmap *,
+			  struct buffer_head **,
+			  sector_t,
+			  union nilfs_binfo *);
+	int (*bop_mark)(struct nilfs_bmap *, __u64, int);
+
+	/* The following functions are internal use only. */
+	int (*bop_last_key)(const struct nilfs_bmap *, __u64 *);
+	int (*bop_check_insert)(const struct nilfs_bmap *, __u64);
+	int (*bop_check_delete)(struct nilfs_bmap *, __u64);
+	int (*bop_gather_data)(struct nilfs_bmap *, __u64 *, __u64 *, int);
+};
+
+
+/**
+ * struct nilfs_bmap_ptr_operations - bmap ptr operation table
+ */
+struct nilfs_bmap_ptr_operations {
+	int (*bpop_prepare_alloc_ptr)(struct nilfs_bmap *,
+				      union nilfs_bmap_ptr_req *);
+	void (*bpop_commit_alloc_ptr)(struct nilfs_bmap *,
+				      union nilfs_bmap_ptr_req *);
+	void (*bpop_abort_alloc_ptr)(struct nilfs_bmap *,
+				     union nilfs_bmap_ptr_req *);
+	int (*bpop_prepare_start_ptr)(struct nilfs_bmap *,
+				      union nilfs_bmap_ptr_req *);
+	void (*bpop_commit_start_ptr)(struct nilfs_bmap *,
+				      union nilfs_bmap_ptr_req *,
+				      sector_t);
+	void (*bpop_abort_start_ptr)(struct nilfs_bmap *,
+				     union nilfs_bmap_ptr_req *);
+	int (*bpop_prepare_end_ptr)(struct nilfs_bmap *,
+				    union nilfs_bmap_ptr_req *);
+	void (*bpop_commit_end_ptr)(struct nilfs_bmap *,
+				    union nilfs_bmap_ptr_req *);
+	void (*bpop_abort_end_ptr)(struct nilfs_bmap *,
+				   union nilfs_bmap_ptr_req *);
+
+	int (*bpop_translate)(const struct nilfs_bmap *, __u64, __u64 *);
+};
+
+
+#define NILFS_BMAP_SIZE		(NILFS_INODE_BMAP_SIZE * sizeof(__le64))
+#define NILFS_BMAP_KEY_BIT	(sizeof(unsigned long) * 8 /* CHAR_BIT */)
+#define NILFS_BMAP_NEW_PTR_INIT	\
+	(1UL << (sizeof(unsigned long) * 8 /* CHAR_BIT */ - 1))
+
+static inline int nilfs_bmap_is_new_ptr(unsigned long ptr)
+{
+	return !!(ptr & NILFS_BMAP_NEW_PTR_INIT);
+}
+
+
+/**
+ * struct nilfs_bmap - bmap structure
+ * @b_u: raw data
+ * @b_sem: semaphore
+ * @b_inode: owner of bmap
+ * @b_ops: bmap operation table
+ * @b_pops: bmap ptr operation table
+ * @b_low: low watermark of conversion
+ * @b_high: high watermark of conversion
+ * @b_last_allocated_key: last allocated key for data block
+ * @b_last_allocated_ptr: last allocated ptr for data block
+ * @b_state: state
+ */
+struct nilfs_bmap {
+	union {
+		__u8 u_flags;
+		__le64 u_data[NILFS_BMAP_SIZE / sizeof(__le64)];
+	} b_u;
+	struct rw_semaphore b_sem;
+	struct inode *b_inode;
+	const struct nilfs_bmap_operations *b_ops;
+	const struct nilfs_bmap_ptr_operations *b_pops;
+	__u64 b_low;
+	__u64 b_high;
+	__u64 b_last_allocated_key;
+	__u64 b_last_allocated_ptr;
+	int b_state;
+};
+
+/* state */
+#define NILFS_BMAP_DIRTY	0x00000001
+
+
+int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *);
+int nilfs_bmap_read(struct nilfs_bmap *, struct nilfs_inode *);
+void nilfs_bmap_write(struct nilfs_bmap *, struct nilfs_inode *);
+int nilfs_bmap_lookup(struct nilfs_bmap *, unsigned long, unsigned long *);
+int nilfs_bmap_insert(struct nilfs_bmap *, unsigned long, unsigned long);
+int nilfs_bmap_delete(struct nilfs_bmap *, unsigned long);
+int nilfs_bmap_last_key(struct nilfs_bmap *, unsigned long *);
+int nilfs_bmap_truncate(struct nilfs_bmap *, unsigned long);
+void nilfs_bmap_clear(struct nilfs_bmap *);
+int nilfs_bmap_propagate(struct nilfs_bmap *, struct buffer_head *);
+void nilfs_bmap_lookup_dirty_buffers(struct nilfs_bmap *, struct list_head *);
+int nilfs_bmap_assign(struct nilfs_bmap *, struct buffer_head **,
+		      unsigned long, union nilfs_binfo *);
+int nilfs_bmap_lookup_at_level(struct nilfs_bmap *, __u64, int, __u64 *);
+int nilfs_bmap_mark(struct nilfs_bmap *, __u64, int);
+
+void nilfs_bmap_init_gc(struct nilfs_bmap *);
+void nilfs_bmap_init_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
+void nilfs_bmap_commit_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
+
+
+/*
+ * Internal use only
+ */
+
+int nilfs_bmap_move_v(const struct nilfs_bmap *, __u64, sector_t);
+int nilfs_bmap_mark_dirty(const struct nilfs_bmap *, __u64);
+
+
+__u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *,
+			      const struct buffer_head *);
+
+__u64 nilfs_bmap_find_target_seq(const struct nilfs_bmap *, __u64);
+__u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *);
+
+int nilfs_bmap_prepare_update(struct nilfs_bmap *,
+			      union nilfs_bmap_ptr_req *,
+			      union nilfs_bmap_ptr_req *);
+void nilfs_bmap_commit_update(struct nilfs_bmap *,
+			      union nilfs_bmap_ptr_req *,
+			      union nilfs_bmap_ptr_req *);
+void nilfs_bmap_abort_update(struct nilfs_bmap *,
+			     union nilfs_bmap_ptr_req *,
+			     union nilfs_bmap_ptr_req *);
+
+void nilfs_bmap_add_blocks(const struct nilfs_bmap *, int);
+void nilfs_bmap_sub_blocks(const struct nilfs_bmap *, int);
+
+
+int nilfs_bmap_get_block(const struct nilfs_bmap *, __u64,
+			 struct buffer_head **);
+void nilfs_bmap_put_block(const struct nilfs_bmap *, struct buffer_head *);
+int nilfs_bmap_get_new_block(const struct nilfs_bmap *, __u64,
+			     struct buffer_head **);
+void nilfs_bmap_delete_block(const struct nilfs_bmap *, struct buffer_head *);
+
+
+/* Assume that bmap semaphore is locked. */
+static inline int nilfs_bmap_dirty(const struct nilfs_bmap *bmap)
+{
+	return !!(bmap->b_state & NILFS_BMAP_DIRTY);
+}
+
+/* Assume that bmap semaphore is locked. */
+static inline void nilfs_bmap_set_dirty(struct nilfs_bmap *bmap)
+{
+	bmap->b_state |= NILFS_BMAP_DIRTY;
+}
+
+/* Assume that bmap semaphore is locked. */
+static inline void nilfs_bmap_clear_dirty(struct nilfs_bmap *bmap)
+{
+	bmap->b_state &= ~NILFS_BMAP_DIRTY;
+}
+
+
+#define NILFS_BMAP_LARGE	0x1
+
+#define NILFS_BMAP_SMALL_LOW	NILFS_DIRECT_KEY_MIN
+#define NILFS_BMAP_SMALL_HIGH	NILFS_DIRECT_KEY_MAX
+#define NILFS_BMAP_LARGE_LOW	NILFS_BTREE_ROOT_NCHILDREN_MAX
+#define NILFS_BMAP_LARGE_HIGH	NILFS_BTREE_KEY_MAX
+
+#endif	/* _NILFS_BMAP_H */
diff --git a/fs/nilfs2/bmap_union.h b/fs/nilfs2/bmap_union.h
new file mode 100644
index 00000000000..d41509bff47
--- /dev/null
+++ b/fs/nilfs2/bmap_union.h
@@ -0,0 +1,42 @@
+/*
+ * bmap_union.h - NILFS block mapping.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_BMAP_UNION_H
+#define _NILFS_BMAP_UNION_H
+
+#include "bmap.h"
+#include "direct.h"
+#include "btree.h"
+
+/**
+ * nilfs_bmap_union -
+ * @bi_bmap: bmap structure
+ * @bi_btree: direct map structure
+ * @bi_direct: B-tree structure
+ */
+union nilfs_bmap_union {
+	struct nilfs_bmap bi_bmap;
+	struct nilfs_direct bi_direct;
+	struct nilfs_btree bi_btree;
+};
+
+#endif	/* _NILFS_BMAP_UNION_H */
diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
new file mode 100644
index 00000000000..4cc07b2c30e
--- /dev/null
+++ b/fs/nilfs2/btnode.c
@@ -0,0 +1,316 @@
+/*
+ * btnode.c - NILFS B-tree node cache
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * This file was originally written by Seiji Kihara <kihara@osrg.net>
+ * and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for
+ * stabilization and simplification.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/mm.h>
+#include <linux/backing-dev.h>
+#include "nilfs.h"
+#include "mdt.h"
+#include "dat.h"
+#include "page.h"
+#include "btnode.h"
+
+
+void nilfs_btnode_cache_init_once(struct address_space *btnc)
+{
+	INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
+	spin_lock_init(&btnc->tree_lock);
+	INIT_LIST_HEAD(&btnc->private_list);
+	spin_lock_init(&btnc->private_lock);
+
+	spin_lock_init(&btnc->i_mmap_lock);
+	INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
+	INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
+}
+
+static struct address_space_operations def_btnode_aops;
+
+void nilfs_btnode_cache_init(struct address_space *btnc)
+{
+	btnc->host = NULL;  /* can safely set to host inode ? */
+	btnc->flags = 0;
+	mapping_set_gfp_mask(btnc, GFP_NOFS);
+	btnc->assoc_mapping = NULL;
+	btnc->backing_dev_info = &default_backing_dev_info;
+	btnc->a_ops = &def_btnode_aops;
+}
+
+void nilfs_btnode_cache_clear(struct address_space *btnc)
+{
+	invalidate_mapping_pages(btnc, 0, -1);
+	truncate_inode_pages(btnc, 0);
+}
+
+int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
+			      sector_t pblocknr, struct buffer_head **pbh,
+			      int newblk)
+{
+	struct buffer_head *bh;
+	struct inode *inode = NILFS_BTNC_I(btnc);
+	int err;
+
+	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	err = -EEXIST; /* internal code */
+	if (newblk) {
+		if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
+			     buffer_dirty(bh))) {
+			brelse(bh);
+			BUG();
+		}
+		bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
+		bh->b_blocknr = blocknr;
+		set_buffer_mapped(bh);
+		set_buffer_uptodate(bh);
+		goto found;
+	}
+
+	if (buffer_uptodate(bh) || buffer_dirty(bh))
+		goto found;
+
+	if (pblocknr == 0) {
+		pblocknr = blocknr;
+		if (inode->i_ino != NILFS_DAT_INO) {
+			struct inode *dat =
+				nilfs_dat_inode(NILFS_I_NILFS(inode));
+
+			/* blocknr is a virtual block number */
+			err = nilfs_dat_translate(dat, blocknr, &pblocknr);
+			if (unlikely(err)) {
+				brelse(bh);
+				goto out_locked;
+			}
+		}
+	}
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		err = -EEXIST; /* internal code */
+		goto found;
+	}
+	set_buffer_mapped(bh);
+	bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
+	bh->b_blocknr = pblocknr; /* set block address for read */
+	bh->b_end_io = end_buffer_read_sync;
+	get_bh(bh);
+	submit_bh(READ, bh);
+	bh->b_blocknr = blocknr; /* set back to the given block address */
+	err = 0;
+found:
+	*pbh = bh;
+
+out_locked:
+	unlock_page(bh->b_page);
+	page_cache_release(bh->b_page);
+	return err;
+}
+
+int nilfs_btnode_get(struct address_space *btnc, __u64 blocknr,
+		     sector_t pblocknr, struct buffer_head **pbh, int newblk)
+{
+	struct buffer_head *bh;
+	int err;
+
+	err = nilfs_btnode_submit_block(btnc, blocknr, pblocknr, pbh, newblk);
+	if (err == -EEXIST) /* internal code (cache hit) */
+		return 0;
+	if (unlikely(err))
+		return err;
+
+	bh = *pbh;
+	wait_on_buffer(bh);
+	if (!buffer_uptodate(bh)) {
+		brelse(bh);
+		return -EIO;
+	}
+	return 0;
+}
+
+/**
+ * nilfs_btnode_delete - delete B-tree node buffer
+ * @bh: buffer to be deleted
+ *
+ * nilfs_btnode_delete() invalidates the specified buffer and delete the page
+ * including the buffer if the page gets unbusy.
+ */
+void nilfs_btnode_delete(struct buffer_head *bh)
+{
+	struct address_space *mapping;
+	struct page *page = bh->b_page;
+	pgoff_t index = page_index(page);
+	int still_dirty;
+
+	page_cache_get(page);
+	lock_page(page);
+	wait_on_page_writeback(page);
+
+	nilfs_forget_buffer(bh);
+	still_dirty = PageDirty(page);
+	mapping = page->mapping;
+	unlock_page(page);
+	page_cache_release(page);
+
+	if (!still_dirty && mapping)
+		invalidate_inode_pages2_range(mapping, index, index);
+}
+
+/**
+ * nilfs_btnode_prepare_change_key
+ *  prepare to move contents of the block for old key to one of new key.
+ *  the old buffer will not be removed, but might be reused for new buffer.
+ *  it might return -ENOMEM because of memory allocation errors,
+ *  and might return -EIO because of disk read errors.
+ */
+int nilfs_btnode_prepare_change_key(struct address_space *btnc,
+				    struct nilfs_btnode_chkey_ctxt *ctxt)
+{
+	struct buffer_head *obh, *nbh;
+	struct inode *inode = NILFS_BTNC_I(btnc);
+	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
+	int err;
+
+	if (oldkey == newkey)
+		return 0;
+
+	obh = ctxt->bh;
+	ctxt->newbh = NULL;
+
+	if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
+		lock_page(obh->b_page);
+		/*
+		 * We cannot call radix_tree_preload for the kernels older
+		 * than 2.6.23, because it is not exported for modules.
+		 */
+		err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
+		if (err)
+			goto failed_unlock;
+		/* BUG_ON(oldkey != obh->b_page->index); */
+		if (unlikely(oldkey != obh->b_page->index))
+			NILFS_PAGE_BUG(obh->b_page,
+				       "invalid oldkey %lld (newkey=%lld)",
+				       (unsigned long long)oldkey,
+				       (unsigned long long)newkey);
+
+retry:
+		spin_lock_irq(&btnc->tree_lock);
+		err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
+		spin_unlock_irq(&btnc->tree_lock);
+		/*
+		 * Note: page->index will not change to newkey until
+		 * nilfs_btnode_commit_change_key() will be called.
+		 * To protect the page in intermediate state, the page lock
+		 * is held.
+		 */
+		radix_tree_preload_end();
+		if (!err)
+			return 0;
+		else if (err != -EEXIST)
+			goto failed_unlock;
+
+		err = invalidate_inode_pages2_range(btnc, newkey, newkey);
+		if (!err)
+			goto retry;
+		/* fallback to copy mode */
+		unlock_page(obh->b_page);
+	}
+
+	err = nilfs_btnode_get(btnc, newkey, 0, &nbh, 1);
+	if (likely(!err)) {
+		BUG_ON(nbh == obh);
+		ctxt->newbh = nbh;
+	}
+	return err;
+
+ failed_unlock:
+	unlock_page(obh->b_page);
+	return err;
+}
+
+/**
+ * nilfs_btnode_commit_change_key
+ *  commit the change_key operation prepared by prepare_change_key().
+ */
+void nilfs_btnode_commit_change_key(struct address_space *btnc,
+				    struct nilfs_btnode_chkey_ctxt *ctxt)
+{
+	struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
+	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
+	struct page *opage;
+
+	if (oldkey == newkey)
+		return;
+
+	if (nbh == NULL) {	/* blocksize == pagesize */
+		opage = obh->b_page;
+		if (unlikely(oldkey != opage->index))
+			NILFS_PAGE_BUG(opage,
+				       "invalid oldkey %lld (newkey=%lld)",
+				       (unsigned long long)oldkey,
+				       (unsigned long long)newkey);
+		if (!test_set_buffer_dirty(obh) && TestSetPageDirty(opage))
+			BUG();
+
+		spin_lock_irq(&btnc->tree_lock);
+		radix_tree_delete(&btnc->page_tree, oldkey);
+		radix_tree_tag_set(&btnc->page_tree, newkey,
+				   PAGECACHE_TAG_DIRTY);
+		spin_unlock_irq(&btnc->tree_lock);
+
+		opage->index = obh->b_blocknr = newkey;
+		unlock_page(opage);
+	} else {
+		nilfs_copy_buffer(nbh, obh);
+		nilfs_btnode_mark_dirty(nbh);
+
+		nbh->b_blocknr = newkey;
+		ctxt->bh = nbh;
+		nilfs_btnode_delete(obh); /* will decrement bh->b_count */
+	}
+}
+
+/**
+ * nilfs_btnode_abort_change_key
+ *  abort the change_key operation prepared by prepare_change_key().
+ */
+void nilfs_btnode_abort_change_key(struct address_space *btnc,
+				   struct nilfs_btnode_chkey_ctxt *ctxt)
+{
+	struct buffer_head *nbh = ctxt->newbh;
+	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
+
+	if (oldkey == newkey)
+		return;
+
+	if (nbh == NULL) {	/* blocksize == pagesize */
+		spin_lock_irq(&btnc->tree_lock);
+		radix_tree_delete(&btnc->page_tree, newkey);
+		spin_unlock_irq(&btnc->tree_lock);
+		unlock_page(ctxt->bh->b_page);
+	} else
+		brelse(nbh);
+}
diff --git a/fs/nilfs2/btnode.h b/fs/nilfs2/btnode.h
new file mode 100644
index 00000000000..35faa86444a
--- /dev/null
+++ b/fs/nilfs2/btnode.h
@@ -0,0 +1,58 @@
+/*
+ * btnode.h - NILFS B-tree node cache
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Seiji Kihara <kihara@osrg.net>
+ * Revised by Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#ifndef _NILFS_BTNODE_H
+#define _NILFS_BTNODE_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/backing-dev.h>
+
+
+struct nilfs_btnode_chkey_ctxt {
+	__u64 oldkey;
+	__u64 newkey;
+	struct buffer_head *bh;
+	struct buffer_head *newbh;
+};
+
+void nilfs_btnode_cache_init_once(struct address_space *);
+void nilfs_btnode_cache_init(struct address_space *);
+void nilfs_btnode_cache_clear(struct address_space *);
+int nilfs_btnode_submit_block(struct address_space *, __u64, sector_t,
+			      struct buffer_head **, int);
+int nilfs_btnode_get(struct address_space *, __u64, sector_t,
+		     struct buffer_head **, int);
+void nilfs_btnode_delete(struct buffer_head *);
+int nilfs_btnode_prepare_change_key(struct address_space *,
+				    struct nilfs_btnode_chkey_ctxt *);
+void nilfs_btnode_commit_change_key(struct address_space *,
+				    struct nilfs_btnode_chkey_ctxt *);
+void nilfs_btnode_abort_change_key(struct address_space *,
+				   struct nilfs_btnode_chkey_ctxt *);
+
+#define nilfs_btnode_mark_dirty(bh)	nilfs_mark_buffer_dirty(bh)
+
+
+#endif	/* _NILFS_BTNODE_H */
diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
new file mode 100644
index 00000000000..6b37a276729
--- /dev/null
+++ b/fs/nilfs2/btree.c
@@ -0,0 +1,2269 @@
+/*
+ * btree.c - NILFS B-tree.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/pagevec.h>
+#include "nilfs.h"
+#include "page.h"
+#include "btnode.h"
+#include "btree.h"
+#include "alloc.h"
+
+/**
+ * struct nilfs_btree_path - A path on which B-tree operations are executed
+ * @bp_bh: buffer head of node block
+ * @bp_sib_bh: buffer head of sibling node block
+ * @bp_index: index of child node
+ * @bp_oldreq: ptr end request for old ptr
+ * @bp_newreq: ptr alloc request for new ptr
+ * @bp_op: rebalance operation
+ */
+struct nilfs_btree_path {
+	struct buffer_head *bp_bh;
+	struct buffer_head *bp_sib_bh;
+	int bp_index;
+	union nilfs_bmap_ptr_req bp_oldreq;
+	union nilfs_bmap_ptr_req bp_newreq;
+	struct nilfs_btnode_chkey_ctxt bp_ctxt;
+	void (*bp_op)(struct nilfs_btree *, struct nilfs_btree_path *,
+		      int, __u64 *, __u64 *);
+};
+
+/*
+ * B-tree path operations
+ */
+
+static struct kmem_cache *nilfs_btree_path_cache;
+
+int __init nilfs_btree_path_cache_init(void)
+{
+	nilfs_btree_path_cache =
+		kmem_cache_create("nilfs2_btree_path_cache",
+				  sizeof(struct nilfs_btree_path) *
+				  NILFS_BTREE_LEVEL_MAX, 0, 0, NULL);
+	return (nilfs_btree_path_cache != NULL) ? 0 : -ENOMEM;
+}
+
+void nilfs_btree_path_cache_destroy(void)
+{
+	kmem_cache_destroy(nilfs_btree_path_cache);
+}
+
+static inline struct nilfs_btree_path *
+nilfs_btree_alloc_path(const struct nilfs_btree *btree)
+{
+	return (struct nilfs_btree_path *)
+		kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
+}
+
+static inline void nilfs_btree_free_path(const struct nilfs_btree *btree,
+					 struct nilfs_btree_path *path)
+{
+	kmem_cache_free(nilfs_btree_path_cache, path);
+}
+
+static void nilfs_btree_init_path(const struct nilfs_btree *btree,
+				  struct nilfs_btree_path *path)
+{
+	int level;
+
+	for (level = NILFS_BTREE_LEVEL_DATA;
+	     level < NILFS_BTREE_LEVEL_MAX;
+	     level++) {
+		path[level].bp_bh = NULL;
+		path[level].bp_sib_bh = NULL;
+		path[level].bp_index = 0;
+		path[level].bp_oldreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
+		path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
+		path[level].bp_op = NULL;
+	}
+}
+
+static void nilfs_btree_clear_path(const struct nilfs_btree *btree,
+				   struct nilfs_btree_path *path)
+{
+	int level;
+
+	for (level = NILFS_BTREE_LEVEL_DATA;
+	     level < NILFS_BTREE_LEVEL_MAX;
+	     level++) {
+		if (path[level].bp_bh != NULL) {
+			nilfs_bmap_put_block(&btree->bt_bmap,
+					     path[level].bp_bh);
+			path[level].bp_bh = NULL;
+		}
+		/* sib_bh is released or deleted by prepare or commit
+		 * operations. */
+		path[level].bp_sib_bh = NULL;
+		path[level].bp_index = 0;
+		path[level].bp_oldreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
+		path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
+		path[level].bp_op = NULL;
+	}
+}
+
+
+/*
+ * B-tree node operations
+ */
+
+static inline int
+nilfs_btree_node_get_flags(const struct nilfs_btree *btree,
+			   const struct nilfs_btree_node *node)
+{
+	return node->bn_flags;
+}
+
+static inline void
+nilfs_btree_node_set_flags(struct nilfs_btree *btree,
+			   struct nilfs_btree_node *node,
+			   int flags)
+{
+	node->bn_flags = flags;
+}
+
+static inline int nilfs_btree_node_root(const struct nilfs_btree *btree,
+					const struct nilfs_btree_node *node)
+{
+	return nilfs_btree_node_get_flags(btree, node) & NILFS_BTREE_NODE_ROOT;
+}
+
+static inline int
+nilfs_btree_node_get_level(const struct nilfs_btree *btree,
+			   const struct nilfs_btree_node *node)
+{
+	return node->bn_level;
+}
+
+static inline void
+nilfs_btree_node_set_level(struct nilfs_btree *btree,
+			   struct nilfs_btree_node *node,
+			   int level)
+{
+	node->bn_level = level;
+}
+
+static inline int
+nilfs_btree_node_get_nchildren(const struct nilfs_btree *btree,
+			       const struct nilfs_btree_node *node)
+{
+	return le16_to_cpu(node->bn_nchildren);
+}
+
+static inline void
+nilfs_btree_node_set_nchildren(struct nilfs_btree *btree,
+			       struct nilfs_btree_node *node,
+			       int nchildren)
+{
+	node->bn_nchildren = cpu_to_le16(nchildren);
+}
+
+static inline int
+nilfs_btree_node_size(const struct nilfs_btree *btree)
+{
+	return 1 << btree->bt_bmap.b_inode->i_blkbits;
+}
+
+static inline int
+nilfs_btree_node_nchildren_min(const struct nilfs_btree *btree,
+			       const struct nilfs_btree_node *node)
+{
+	return nilfs_btree_node_root(btree, node) ?
+		NILFS_BTREE_ROOT_NCHILDREN_MIN :
+		NILFS_BTREE_NODE_NCHILDREN_MIN(nilfs_btree_node_size(btree));
+}
+
+static inline int
+nilfs_btree_node_nchildren_max(const struct nilfs_btree *btree,
+			       const struct nilfs_btree_node *node)
+{
+	return nilfs_btree_node_root(btree, node) ?
+		NILFS_BTREE_ROOT_NCHILDREN_MAX :
+		NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(btree));
+}
+
+static inline __le64 *
+nilfs_btree_node_dkeys(const struct nilfs_btree *btree,
+		       const struct nilfs_btree_node *node)
+{
+	return (__le64 *)((char *)(node + 1) +
+			  (nilfs_btree_node_root(btree, node) ?
+			   0 : NILFS_BTREE_NODE_EXTRA_PAD_SIZE));
+}
+
+static inline __le64 *
+nilfs_btree_node_dptrs(const struct nilfs_btree *btree,
+		       const struct nilfs_btree_node *node)
+{
+	return (__le64 *)(nilfs_btree_node_dkeys(btree, node) +
+			  nilfs_btree_node_nchildren_max(btree, node));
+}
+
+static inline __u64
+nilfs_btree_node_get_key(const struct nilfs_btree *btree,
+			 const struct nilfs_btree_node *node, int index)
+{
+	return nilfs_bmap_dkey_to_key(*(nilfs_btree_node_dkeys(btree, node) +
+					index));
+}
+
+static inline void
+nilfs_btree_node_set_key(struct nilfs_btree *btree,
+			 struct nilfs_btree_node *node, int index, __u64 key)
+{
+	*(nilfs_btree_node_dkeys(btree, node) + index) =
+		nilfs_bmap_key_to_dkey(key);
+}
+
+static inline __u64
+nilfs_btree_node_get_ptr(const struct nilfs_btree *btree,
+			 const struct nilfs_btree_node *node,
+			 int index)
+{
+	return nilfs_bmap_dptr_to_ptr(*(nilfs_btree_node_dptrs(btree, node) +
+					index));
+}
+
+static inline void
+nilfs_btree_node_set_ptr(struct nilfs_btree *btree,
+			 struct nilfs_btree_node *node,
+			 int index,
+			 __u64 ptr)
+{
+	*(nilfs_btree_node_dptrs(btree, node) + index) =
+		nilfs_bmap_ptr_to_dptr(ptr);
+}
+
+static void nilfs_btree_node_init(struct nilfs_btree *btree,
+				  struct nilfs_btree_node *node,
+				  int flags, int level, int nchildren,
+				  const __u64 *keys, const __u64 *ptrs)
+{
+	__le64 *dkeys;
+	__le64 *dptrs;
+	int i;
+
+	nilfs_btree_node_set_flags(btree, node, flags);
+	nilfs_btree_node_set_level(btree, node, level);
+	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+
+	dkeys = nilfs_btree_node_dkeys(btree, node);
+	dptrs = nilfs_btree_node_dptrs(btree, node);
+	for (i = 0; i < nchildren; i++) {
+		dkeys[i] = nilfs_bmap_key_to_dkey(keys[i]);
+		dptrs[i] = nilfs_bmap_ptr_to_dptr(ptrs[i]);
+	}
+}
+
+/* Assume the buffer heads corresponding to left and right are locked. */
+static void nilfs_btree_node_move_left(struct nilfs_btree *btree,
+				       struct nilfs_btree_node *left,
+				       struct nilfs_btree_node *right,
+				       int n)
+{
+	__le64 *ldkeys, *rdkeys;
+	__le64 *ldptrs, *rdptrs;
+	int lnchildren, rnchildren;
+
+	ldkeys = nilfs_btree_node_dkeys(btree, left);
+	ldptrs = nilfs_btree_node_dptrs(btree, left);
+	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+
+	rdkeys = nilfs_btree_node_dkeys(btree, right);
+	rdptrs = nilfs_btree_node_dptrs(btree, right);
+	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+
+	memcpy(ldkeys + lnchildren, rdkeys, n * sizeof(*rdkeys));
+	memcpy(ldptrs + lnchildren, rdptrs, n * sizeof(*rdptrs));
+	memmove(rdkeys, rdkeys + n, (rnchildren - n) * sizeof(*rdkeys));
+	memmove(rdptrs, rdptrs + n, (rnchildren - n) * sizeof(*rdptrs));
+
+	lnchildren += n;
+	rnchildren -= n;
+	nilfs_btree_node_set_nchildren(btree, left, lnchildren);
+	nilfs_btree_node_set_nchildren(btree, right, rnchildren);
+}
+
+/* Assume that the buffer heads corresponding to left and right are locked. */
+static void nilfs_btree_node_move_right(struct nilfs_btree *btree,
+					struct nilfs_btree_node *left,
+					struct nilfs_btree_node *right,
+					int n)
+{
+	__le64 *ldkeys, *rdkeys;
+	__le64 *ldptrs, *rdptrs;
+	int lnchildren, rnchildren;
+
+	ldkeys = nilfs_btree_node_dkeys(btree, left);
+	ldptrs = nilfs_btree_node_dptrs(btree, left);
+	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+
+	rdkeys = nilfs_btree_node_dkeys(btree, right);
+	rdptrs = nilfs_btree_node_dptrs(btree, right);
+	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+
+	memmove(rdkeys + n, rdkeys, rnchildren * sizeof(*rdkeys));
+	memmove(rdptrs + n, rdptrs, rnchildren * sizeof(*rdptrs));
+	memcpy(rdkeys, ldkeys + lnchildren - n, n * sizeof(*rdkeys));
+	memcpy(rdptrs, ldptrs + lnchildren - n, n * sizeof(*rdptrs));
+
+	lnchildren -= n;
+	rnchildren += n;
+	nilfs_btree_node_set_nchildren(btree, left, lnchildren);
+	nilfs_btree_node_set_nchildren(btree, right, rnchildren);
+}
+
+/* Assume that the buffer head corresponding to node is locked. */
+static void nilfs_btree_node_insert(struct nilfs_btree *btree,
+				    struct nilfs_btree_node *node,
+				    __u64 key, __u64 ptr, int index)
+{
+	__le64 *dkeys;
+	__le64 *dptrs;
+	int nchildren;
+
+	dkeys = nilfs_btree_node_dkeys(btree, node);
+	dptrs = nilfs_btree_node_dptrs(btree, node);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	if (index < nchildren) {
+		memmove(dkeys + index + 1, dkeys + index,
+			(nchildren - index) * sizeof(*dkeys));
+		memmove(dptrs + index + 1, dptrs + index,
+			(nchildren - index) * sizeof(*dptrs));
+	}
+	dkeys[index] = nilfs_bmap_key_to_dkey(key);
+	dptrs[index] = nilfs_bmap_ptr_to_dptr(ptr);
+	nchildren++;
+	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+}
+
+/* Assume that the buffer head corresponding to node is locked. */
+static void nilfs_btree_node_delete(struct nilfs_btree *btree,
+				    struct nilfs_btree_node *node,
+				    __u64 *keyp, __u64 *ptrp, int index)
+{
+	__u64 key;
+	__u64 ptr;
+	__le64 *dkeys;
+	__le64 *dptrs;
+	int nchildren;
+
+	dkeys = nilfs_btree_node_dkeys(btree, node);
+	dptrs = nilfs_btree_node_dptrs(btree, node);
+	key = nilfs_bmap_dkey_to_key(dkeys[index]);
+	ptr = nilfs_bmap_dptr_to_ptr(dptrs[index]);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	if (keyp != NULL)
+		*keyp = key;
+	if (ptrp != NULL)
+		*ptrp = ptr;
+
+	if (index < nchildren - 1) {
+		memmove(dkeys + index, dkeys + index + 1,
+			(nchildren - index - 1) * sizeof(*dkeys));
+		memmove(dptrs + index, dptrs + index + 1,
+			(nchildren - index - 1) * sizeof(*dptrs));
+	}
+	nchildren--;
+	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+}
+
+static int nilfs_btree_node_lookup(const struct nilfs_btree *btree,
+				   const struct nilfs_btree_node *node,
+				   __u64 key, int *indexp)
+{
+	__u64 nkey;
+	int index, low, high, s;
+
+	/* binary search */
+	low = 0;
+	high = nilfs_btree_node_get_nchildren(btree, node) - 1;
+	index = 0;
+	s = 0;
+	while (low <= high) {
+		index = (low + high) / 2;
+		nkey = nilfs_btree_node_get_key(btree, node, index);
+		if (nkey == key) {
+			s = 0;
+			goto out;
+		} else if (nkey < key) {
+			low = index + 1;
+			s = -1;
+		} else {
+			high = index - 1;
+			s = 1;
+		}
+	}
+
+	/* adjust index */
+	if (nilfs_btree_node_get_level(btree, node) >
+	    NILFS_BTREE_LEVEL_NODE_MIN) {
+		if ((s > 0) && (index > 0))
+			index--;
+	} else if (s < 0)
+		index++;
+
+ out:
+	*indexp = index;
+
+	return s == 0;
+}
+
+static inline struct nilfs_btree_node *
+nilfs_btree_get_root(const struct nilfs_btree *btree)
+{
+	return (struct nilfs_btree_node *)btree->bt_bmap.b_u.u_data;
+}
+
+static inline struct nilfs_btree_node *
+nilfs_btree_get_nonroot_node(const struct nilfs_btree *btree,
+			     const struct nilfs_btree_path *path,
+			     int level)
+{
+	return (struct nilfs_btree_node *)path[level].bp_bh->b_data;
+}
+
+static inline struct nilfs_btree_node *
+nilfs_btree_get_sib_node(const struct nilfs_btree *btree,
+			 const struct nilfs_btree_path *path,
+			 int level)
+{
+	return (struct nilfs_btree_node *)path[level].bp_sib_bh->b_data;
+}
+
+static inline int nilfs_btree_height(const struct nilfs_btree *btree)
+{
+	return nilfs_btree_node_get_level(btree, nilfs_btree_get_root(btree))
+		+ 1;
+}
+
+static inline struct nilfs_btree_node *
+nilfs_btree_get_node(const struct nilfs_btree *btree,
+		     const struct nilfs_btree_path *path,
+		     int level)
+{
+	return (level == nilfs_btree_height(btree) - 1) ?
+		nilfs_btree_get_root(btree) :
+		nilfs_btree_get_nonroot_node(btree, path, level);
+}
+
+static int nilfs_btree_do_lookup(const struct nilfs_btree *btree,
+				 struct nilfs_btree_path *path,
+				 __u64 key, __u64 *ptrp, int minlevel)
+{
+	struct nilfs_btree_node *node;
+	__u64 ptr;
+	int level, index, found, ret;
+
+	node = nilfs_btree_get_root(btree);
+	level = nilfs_btree_node_get_level(btree, node);
+	if ((level < minlevel) ||
+	    (nilfs_btree_node_get_nchildren(btree, node) <= 0))
+		return -ENOENT;
+
+	found = nilfs_btree_node_lookup(btree, node, key, &index);
+	ptr = nilfs_btree_node_get_ptr(btree, node, index);
+	path[level].bp_bh = NULL;
+	path[level].bp_index = index;
+
+	for (level--; level >= minlevel; level--) {
+		ret = nilfs_bmap_get_block(&btree->bt_bmap, ptr,
+					   &path[level].bp_bh);
+		if (ret < 0)
+			return ret;
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		BUG_ON(level != nilfs_btree_node_get_level(btree, node));
+		if (!found)
+			found = nilfs_btree_node_lookup(btree, node, key,
+							&index);
+		else
+			index = 0;
+		if (index < nilfs_btree_node_nchildren_max(btree, node))
+			ptr = nilfs_btree_node_get_ptr(btree, node, index);
+		else {
+			WARN_ON(found || level != NILFS_BTREE_LEVEL_NODE_MIN);
+			/* insert */
+			ptr = NILFS_BMAP_INVALID_PTR;
+		}
+		path[level].bp_index = index;
+	}
+	if (!found)
+		return -ENOENT;
+
+	if (ptrp != NULL)
+		*ptrp = ptr;
+
+	return 0;
+}
+
+static int nilfs_btree_do_lookup_last(const struct nilfs_btree *btree,
+				      struct nilfs_btree_path *path,
+				      __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node;
+	__u64 ptr;
+	int index, level, ret;
+
+	node = nilfs_btree_get_root(btree);
+	index = nilfs_btree_node_get_nchildren(btree, node) - 1;
+	if (index < 0)
+		return -ENOENT;
+	level = nilfs_btree_node_get_level(btree, node);
+	ptr = nilfs_btree_node_get_ptr(btree, node, index);
+	path[level].bp_bh = NULL;
+	path[level].bp_index = index;
+
+	for (level--; level > 0; level--) {
+		ret = nilfs_bmap_get_block(&btree->bt_bmap, ptr,
+					   &path[level].bp_bh);
+		if (ret < 0)
+			return ret;
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		BUG_ON(level != nilfs_btree_node_get_level(btree, node));
+		index = nilfs_btree_node_get_nchildren(btree, node) - 1;
+		ptr = nilfs_btree_node_get_ptr(btree, node, index);
+		path[level].bp_index = index;
+	}
+
+	if (keyp != NULL)
+		*keyp = nilfs_btree_node_get_key(btree, node, index);
+	if (ptrp != NULL)
+		*ptrp = ptr;
+
+	return 0;
+}
+
+static int nilfs_btree_lookup(const struct nilfs_bmap *bmap,
+			      __u64 key, int level, __u64 *ptrp)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	__u64 ptr;
+	int ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
+
+	if (ptrp != NULL)
+		*ptrp = ptr;
+
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+
+	return ret;
+}
+
+static void nilfs_btree_promote_key(struct nilfs_btree *btree,
+				    struct nilfs_btree_path *path,
+				    int level, __u64 key)
+{
+	if (level < nilfs_btree_height(btree) - 1) {
+		do {
+			lock_buffer(path[level].bp_bh);
+			nilfs_btree_node_set_key(
+				btree,
+				nilfs_btree_get_nonroot_node(
+					btree, path, level),
+				path[level].bp_index, key);
+			if (!buffer_dirty(path[level].bp_bh))
+				nilfs_btnode_mark_dirty(path[level].bp_bh);
+			unlock_buffer(path[level].bp_bh);
+		} while ((path[level].bp_index == 0) &&
+			 (++level < nilfs_btree_height(btree) - 1));
+	}
+
+	/* root */
+	if (level == nilfs_btree_height(btree) - 1) {
+		nilfs_btree_node_set_key(btree,
+					 nilfs_btree_get_root(btree),
+					 path[level].bp_index, key);
+	}
+}
+
+static void nilfs_btree_do_insert(struct nilfs_btree *btree,
+				  struct nilfs_btree_path *path,
+				  int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node;
+
+	if (level < nilfs_btree_height(btree) - 1) {
+		lock_buffer(path[level].bp_bh);
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		nilfs_btree_node_insert(btree, node, *keyp, *ptrp,
+					path[level].bp_index);
+		if (!buffer_dirty(path[level].bp_bh))
+			nilfs_btnode_mark_dirty(path[level].bp_bh);
+		unlock_buffer(path[level].bp_bh);
+
+		if (path[level].bp_index == 0)
+			nilfs_btree_promote_key(btree, path, level + 1,
+						nilfs_btree_node_get_key(
+							btree, node, 0));
+	} else {
+		node = nilfs_btree_get_root(btree);
+		nilfs_btree_node_insert(btree, node, *keyp, *ptrp,
+					path[level].bp_index);
+	}
+}
+
+static void nilfs_btree_carry_left(struct nilfs_btree *btree,
+				   struct nilfs_btree_path *path,
+				   int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *left;
+	int nchildren, lnchildren, n, move;
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	left = nilfs_btree_get_sib_node(btree, path, level);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+	move = 0;
+
+	n = (nchildren + lnchildren + 1) / 2 - lnchildren;
+	if (n > path[level].bp_index) {
+		/* move insert point */
+		n--;
+		move = 1;
+	}
+
+	nilfs_btree_node_move_left(btree, left, node, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	nilfs_btree_promote_key(btree, path, level + 1,
+				nilfs_btree_node_get_key(btree, node, 0));
+
+	if (move) {
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_bh);
+		path[level].bp_bh = path[level].bp_sib_bh;
+		path[level].bp_sib_bh = NULL;
+		path[level].bp_index += lnchildren;
+		path[level + 1].bp_index--;
+	} else {
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+		path[level].bp_sib_bh = NULL;
+		path[level].bp_index -= n;
+	}
+
+	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
+}
+
+static void nilfs_btree_carry_right(struct nilfs_btree *btree,
+				    struct nilfs_btree_path *path,
+				    int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *right;
+	int nchildren, rnchildren, n, move;
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	right = nilfs_btree_get_sib_node(btree, path, level);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+	move = 0;
+
+	n = (nchildren + rnchildren + 1) / 2 - rnchildren;
+	if (n > nchildren - path[level].bp_index) {
+		/* move insert point */
+		n--;
+		move = 1;
+	}
+
+	nilfs_btree_node_move_right(btree, node, right, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	path[level + 1].bp_index++;
+	nilfs_btree_promote_key(btree, path, level + 1,
+				nilfs_btree_node_get_key(btree, right, 0));
+	path[level + 1].bp_index--;
+
+	if (move) {
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_bh);
+		path[level].bp_bh = path[level].bp_sib_bh;
+		path[level].bp_sib_bh = NULL;
+		path[level].bp_index -=
+			nilfs_btree_node_get_nchildren(btree, node);
+		path[level + 1].bp_index++;
+	} else {
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+		path[level].bp_sib_bh = NULL;
+	}
+
+	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
+}
+
+static void nilfs_btree_split(struct nilfs_btree *btree,
+			      struct nilfs_btree_path *path,
+			      int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *right;
+	__u64 newkey;
+	__u64 newptr;
+	int nchildren, n, move;
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	right = nilfs_btree_get_sib_node(btree, path, level);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	move = 0;
+
+	n = (nchildren + 1) / 2;
+	if (n > nchildren - path[level].bp_index) {
+		n--;
+		move = 1;
+	}
+
+	nilfs_btree_node_move_right(btree, node, right, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	newkey = nilfs_btree_node_get_key(btree, right, 0);
+	newptr = path[level].bp_newreq.bpr_ptr;
+
+	if (move) {
+		path[level].bp_index -=
+			nilfs_btree_node_get_nchildren(btree, node);
+		nilfs_btree_node_insert(btree, right, *keyp, *ptrp,
+					path[level].bp_index);
+
+		*keyp = nilfs_btree_node_get_key(btree, right, 0);
+		*ptrp = path[level].bp_newreq.bpr_ptr;
+
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_bh);
+		path[level].bp_bh = path[level].bp_sib_bh;
+		path[level].bp_sib_bh = NULL;
+	} else {
+		nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
+
+		*keyp = nilfs_btree_node_get_key(btree, right, 0);
+		*ptrp = path[level].bp_newreq.bpr_ptr;
+
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+		path[level].bp_sib_bh = NULL;
+	}
+
+	path[level + 1].bp_index++;
+}
+
+static void nilfs_btree_grow(struct nilfs_btree *btree,
+			     struct nilfs_btree_path *path,
+			     int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *root, *child;
+	int n;
+
+	lock_buffer(path[level].bp_sib_bh);
+
+	root = nilfs_btree_get_root(btree);
+	child = nilfs_btree_get_sib_node(btree, path, level);
+
+	n = nilfs_btree_node_get_nchildren(btree, root);
+
+	nilfs_btree_node_move_right(btree, root, child, n);
+	nilfs_btree_node_set_level(btree, root, level + 1);
+
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_sib_bh);
+
+	path[level].bp_bh = path[level].bp_sib_bh;
+	path[level].bp_sib_bh = NULL;
+
+	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
+
+	*keyp = nilfs_btree_node_get_key(btree, child, 0);
+	*ptrp = path[level].bp_newreq.bpr_ptr;
+}
+
+static __u64 nilfs_btree_find_near(const struct nilfs_btree *btree,
+				   const struct nilfs_btree_path *path)
+{
+	struct nilfs_btree_node *node;
+	int level;
+
+	if (path == NULL)
+		return NILFS_BMAP_INVALID_PTR;
+
+	/* left sibling */
+	level = NILFS_BTREE_LEVEL_NODE_MIN;
+	if (path[level].bp_index > 0) {
+		node = nilfs_btree_get_node(btree, path, level);
+		return nilfs_btree_node_get_ptr(btree, node,
+						path[level].bp_index - 1);
+	}
+
+	/* parent */
+	level = NILFS_BTREE_LEVEL_NODE_MIN + 1;
+	if (level <= nilfs_btree_height(btree) - 1) {
+		node = nilfs_btree_get_node(btree, path, level);
+		return nilfs_btree_node_get_ptr(btree, node,
+						path[level].bp_index);
+	}
+
+	return NILFS_BMAP_INVALID_PTR;
+}
+
+static __u64 nilfs_btree_find_target_v(const struct nilfs_btree *btree,
+				       const struct nilfs_btree_path *path,
+				       __u64 key)
+{
+	__u64 ptr;
+
+	ptr = nilfs_bmap_find_target_seq(&btree->bt_bmap, key);
+	if (ptr != NILFS_BMAP_INVALID_PTR)
+		/* sequential access */
+		return ptr;
+	else {
+		ptr = nilfs_btree_find_near(btree, path);
+		if (ptr != NILFS_BMAP_INVALID_PTR)
+			/* near */
+			return ptr;
+	}
+	/* block group */
+	return nilfs_bmap_find_target_in_group(&btree->bt_bmap);
+}
+
+static void nilfs_btree_set_target_v(struct nilfs_btree *btree, __u64 key,
+				     __u64 ptr)
+{
+	btree->bt_bmap.b_last_allocated_key = key;
+	btree->bt_bmap.b_last_allocated_ptr = ptr;
+}
+
+static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
+				      struct nilfs_btree_path *path,
+				      int *levelp, __u64 key, __u64 ptr,
+				      struct nilfs_bmap_stats *stats)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree_node *node, *parent, *sib;
+	__u64 sibptr;
+	int pindex, level, ret;
+
+	stats->bs_nblocks = 0;
+	level = NILFS_BTREE_LEVEL_DATA;
+
+	/* allocate a new ptr for data block */
+	if (btree->bt_ops->btop_find_target != NULL)
+		path[level].bp_newreq.bpr_ptr =
+			btree->bt_ops->btop_find_target(btree, path, key);
+
+	ret = btree->bt_bmap.b_pops->bpop_prepare_alloc_ptr(
+		&btree->bt_bmap, &path[level].bp_newreq);
+	if (ret < 0)
+		goto err_out_data;
+
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
+	     level < nilfs_btree_height(btree) - 1;
+	     level++) {
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		if (nilfs_btree_node_get_nchildren(btree, node) <
+		    nilfs_btree_node_nchildren_max(btree, node)) {
+			path[level].bp_op = nilfs_btree_do_insert;
+			stats->bs_nblocks++;
+			goto out;
+		}
+
+		parent = nilfs_btree_get_node(btree, path, level + 1);
+		pindex = path[level + 1].bp_index;
+
+		/* left sibling */
+		if (pindex > 0) {
+			sibptr = nilfs_btree_node_get_ptr(btree, parent,
+							  pindex - 1);
+			ret = nilfs_bmap_get_block(&btree->bt_bmap, sibptr,
+						   &bh);
+			if (ret < 0)
+				goto err_out_child_node;
+			sib = (struct nilfs_btree_node *)bh->b_data;
+			if (nilfs_btree_node_get_nchildren(btree, sib) <
+			    nilfs_btree_node_nchildren_max(btree, sib)) {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_carry_left;
+				stats->bs_nblocks++;
+				goto out;
+			} else
+				nilfs_bmap_put_block(&btree->bt_bmap, bh);
+		}
+
+		/* right sibling */
+		if (pindex <
+		    nilfs_btree_node_get_nchildren(btree, parent) - 1) {
+			sibptr = nilfs_btree_node_get_ptr(btree, parent,
+							  pindex + 1);
+			ret = nilfs_bmap_get_block(&btree->bt_bmap, sibptr,
+						   &bh);
+			if (ret < 0)
+				goto err_out_child_node;
+			sib = (struct nilfs_btree_node *)bh->b_data;
+			if (nilfs_btree_node_get_nchildren(btree, sib) <
+			    nilfs_btree_node_nchildren_max(btree, sib)) {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_carry_right;
+				stats->bs_nblocks++;
+				goto out;
+			} else
+				nilfs_bmap_put_block(&btree->bt_bmap, bh);
+		}
+
+		/* split */
+		path[level].bp_newreq.bpr_ptr =
+			path[level - 1].bp_newreq.bpr_ptr + 1;
+		ret = btree->bt_bmap.b_pops->bpop_prepare_alloc_ptr(
+			&btree->bt_bmap, &path[level].bp_newreq);
+		if (ret < 0)
+			goto err_out_child_node;
+		ret = nilfs_bmap_get_new_block(&btree->bt_bmap,
+					       path[level].bp_newreq.bpr_ptr,
+					       &bh);
+		if (ret < 0)
+			goto err_out_curr_node;
+
+		stats->bs_nblocks++;
+
+		lock_buffer(bh);
+		nilfs_btree_node_init(btree,
+				      (struct nilfs_btree_node *)bh->b_data,
+				      0, level, 0, NULL, NULL);
+		unlock_buffer(bh);
+		path[level].bp_sib_bh = bh;
+		path[level].bp_op = nilfs_btree_split;
+	}
+
+	/* root */
+	node = nilfs_btree_get_root(btree);
+	if (nilfs_btree_node_get_nchildren(btree, node) <
+	    nilfs_btree_node_nchildren_max(btree, node)) {
+		path[level].bp_op = nilfs_btree_do_insert;
+		stats->bs_nblocks++;
+		goto out;
+	}
+
+	/* grow */
+	path[level].bp_newreq.bpr_ptr = path[level - 1].bp_newreq.bpr_ptr + 1;
+	ret = btree->bt_bmap.b_pops->bpop_prepare_alloc_ptr(
+		&btree->bt_bmap, &path[level].bp_newreq);
+	if (ret < 0)
+		goto err_out_child_node;
+	ret = nilfs_bmap_get_new_block(&btree->bt_bmap,
+				       path[level].bp_newreq.bpr_ptr, &bh);
+	if (ret < 0)
+		goto err_out_curr_node;
+
+	lock_buffer(bh);
+	nilfs_btree_node_init(btree, (struct nilfs_btree_node *)bh->b_data,
+			      0, level, 0, NULL, NULL);
+	unlock_buffer(bh);
+	path[level].bp_sib_bh = bh;
+	path[level].bp_op = nilfs_btree_grow;
+
+	level++;
+	path[level].bp_op = nilfs_btree_do_insert;
+
+	/* a newly-created node block and a data block are added */
+	stats->bs_nblocks += 2;
+
+	/* success */
+ out:
+	*levelp = level;
+	return ret;
+
+	/* error */
+ err_out_curr_node:
+	btree->bt_bmap.b_pops->bpop_abort_alloc_ptr(&btree->bt_bmap,
+						    &path[level].bp_newreq);
+ err_out_child_node:
+	for (level--; level > NILFS_BTREE_LEVEL_DATA; level--) {
+		nilfs_bmap_delete_block(&btree->bt_bmap, path[level].bp_sib_bh);
+		btree->bt_bmap.b_pops->bpop_abort_alloc_ptr(
+			&btree->bt_bmap, &path[level].bp_newreq);
+
+	}
+
+	btree->bt_bmap.b_pops->bpop_abort_alloc_ptr(&btree->bt_bmap,
+						       &path[level].bp_newreq);
+ err_out_data:
+	*levelp = level;
+	stats->bs_nblocks = 0;
+	return ret;
+}
+
+static void nilfs_btree_commit_insert(struct nilfs_btree *btree,
+				      struct nilfs_btree_path *path,
+				      int maxlevel, __u64 key, __u64 ptr)
+{
+	int level;
+
+	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
+	ptr = path[NILFS_BTREE_LEVEL_DATA].bp_newreq.bpr_ptr;
+	if (btree->bt_ops->btop_set_target != NULL)
+		btree->bt_ops->btop_set_target(btree, key, ptr);
+
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
+		if (btree->bt_bmap.b_pops->bpop_commit_alloc_ptr != NULL) {
+			btree->bt_bmap.b_pops->bpop_commit_alloc_ptr(
+				&btree->bt_bmap, &path[level - 1].bp_newreq);
+		}
+		path[level].bp_op(btree, path, level, &key, &ptr);
+	}
+
+	if (!nilfs_bmap_dirty(&btree->bt_bmap))
+		nilfs_bmap_set_dirty(&btree->bt_bmap);
+}
+
+static int nilfs_btree_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	struct nilfs_bmap_stats stats;
+	int level, ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
+				    NILFS_BTREE_LEVEL_NODE_MIN);
+	if (ret != -ENOENT) {
+		if (ret == 0)
+			ret = -EEXIST;
+		goto out;
+	}
+
+	ret = nilfs_btree_prepare_insert(btree, path, &level, key, ptr, &stats);
+	if (ret < 0)
+		goto out;
+	nilfs_btree_commit_insert(btree, path, level, key, ptr);
+	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
+
+ out:
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+	return ret;
+}
+
+static void nilfs_btree_do_delete(struct nilfs_btree *btree,
+				  struct nilfs_btree_path *path,
+				  int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node;
+
+	if (level < nilfs_btree_height(btree) - 1) {
+		lock_buffer(path[level].bp_bh);
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		nilfs_btree_node_delete(btree, node, keyp, ptrp,
+					path[level].bp_index);
+		if (!buffer_dirty(path[level].bp_bh))
+			nilfs_btnode_mark_dirty(path[level].bp_bh);
+		unlock_buffer(path[level].bp_bh);
+		if (path[level].bp_index == 0)
+			nilfs_btree_promote_key(btree, path, level + 1,
+				nilfs_btree_node_get_key(btree, node, 0));
+	} else {
+		node = nilfs_btree_get_root(btree);
+		nilfs_btree_node_delete(btree, node, keyp, ptrp,
+					path[level].bp_index);
+	}
+}
+
+static void nilfs_btree_borrow_left(struct nilfs_btree *btree,
+				    struct nilfs_btree_path *path,
+				    int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *left;
+	int nchildren, lnchildren, n;
+
+	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	left = nilfs_btree_get_sib_node(btree, path, level);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+
+	n = (nchildren + lnchildren) / 2 - nchildren;
+
+	nilfs_btree_node_move_right(btree, left, node, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	nilfs_btree_promote_key(btree, path, level + 1,
+				nilfs_btree_node_get_key(btree, node, 0));
+
+	nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+	path[level].bp_sib_bh = NULL;
+	path[level].bp_index += n;
+}
+
+static void nilfs_btree_borrow_right(struct nilfs_btree *btree,
+				     struct nilfs_btree_path *path,
+				     int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *right;
+	int nchildren, rnchildren, n;
+
+	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	right = nilfs_btree_get_sib_node(btree, path, level);
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+
+	n = (nchildren + rnchildren) / 2 - nchildren;
+
+	nilfs_btree_node_move_left(btree, node, right, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	path[level + 1].bp_index++;
+	nilfs_btree_promote_key(btree, path, level + 1,
+				nilfs_btree_node_get_key(btree, right, 0));
+	path[level + 1].bp_index--;
+
+	nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+	path[level].bp_sib_bh = NULL;
+}
+
+static void nilfs_btree_concat_left(struct nilfs_btree *btree,
+				    struct nilfs_btree_path *path,
+				    int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *left;
+	int n;
+
+	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	left = nilfs_btree_get_sib_node(btree, path, level);
+
+	n = nilfs_btree_node_get_nchildren(btree, node);
+
+	nilfs_btree_node_move_left(btree, left, node, n);
+
+	if (!buffer_dirty(path[level].bp_sib_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	nilfs_bmap_delete_block(&btree->bt_bmap, path[level].bp_bh);
+	path[level].bp_bh = path[level].bp_sib_bh;
+	path[level].bp_sib_bh = NULL;
+	path[level].bp_index += nilfs_btree_node_get_nchildren(btree, left);
+}
+
+static void nilfs_btree_concat_right(struct nilfs_btree *btree,
+				     struct nilfs_btree_path *path,
+				     int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *node, *right;
+	int n;
+
+	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
+
+	lock_buffer(path[level].bp_bh);
+	lock_buffer(path[level].bp_sib_bh);
+
+	node = nilfs_btree_get_nonroot_node(btree, path, level);
+	right = nilfs_btree_get_sib_node(btree, path, level);
+
+	n = nilfs_btree_node_get_nchildren(btree, right);
+
+	nilfs_btree_node_move_left(btree, node, right, n);
+
+	if (!buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+
+	unlock_buffer(path[level].bp_bh);
+	unlock_buffer(path[level].bp_sib_bh);
+
+	nilfs_bmap_delete_block(&btree->bt_bmap, path[level].bp_sib_bh);
+	path[level].bp_sib_bh = NULL;
+	path[level + 1].bp_index++;
+}
+
+static void nilfs_btree_shrink(struct nilfs_btree *btree,
+			       struct nilfs_btree_path *path,
+			       int level, __u64 *keyp, __u64 *ptrp)
+{
+	struct nilfs_btree_node *root, *child;
+	int n;
+
+	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
+
+	lock_buffer(path[level].bp_bh);
+	root = nilfs_btree_get_root(btree);
+	child = nilfs_btree_get_nonroot_node(btree, path, level);
+
+	nilfs_btree_node_delete(btree, root, NULL, NULL, 0);
+	nilfs_btree_node_set_level(btree, root, level);
+	n = nilfs_btree_node_get_nchildren(btree, child);
+	nilfs_btree_node_move_left(btree, root, child, n);
+	unlock_buffer(path[level].bp_bh);
+
+	nilfs_bmap_delete_block(&btree->bt_bmap, path[level].bp_bh);
+	path[level].bp_bh = NULL;
+}
+
+
+static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
+				      struct nilfs_btree_path *path,
+				      int *levelp,
+				      struct nilfs_bmap_stats *stats)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree_node *node, *parent, *sib;
+	__u64 sibptr;
+	int pindex, level, ret;
+
+	ret = 0;
+	stats->bs_nblocks = 0;
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
+	     level < nilfs_btree_height(btree) - 1;
+	     level++) {
+		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		path[level].bp_oldreq.bpr_ptr =
+			nilfs_btree_node_get_ptr(btree, node,
+						 path[level].bp_index);
+		if (btree->bt_bmap.b_pops->bpop_prepare_end_ptr != NULL) {
+			ret = btree->bt_bmap.b_pops->bpop_prepare_end_ptr(
+				&btree->bt_bmap, &path[level].bp_oldreq);
+			if (ret < 0)
+				goto err_out_child_node;
+		}
+
+		if (nilfs_btree_node_get_nchildren(btree, node) >
+		    nilfs_btree_node_nchildren_min(btree, node)) {
+			path[level].bp_op = nilfs_btree_do_delete;
+			stats->bs_nblocks++;
+			goto out;
+		}
+
+		parent = nilfs_btree_get_node(btree, path, level + 1);
+		pindex = path[level + 1].bp_index;
+
+		if (pindex > 0) {
+			/* left sibling */
+			sibptr = nilfs_btree_node_get_ptr(btree, parent,
+							  pindex - 1);
+			ret = nilfs_bmap_get_block(&btree->bt_bmap, sibptr,
+						   &bh);
+			if (ret < 0)
+				goto err_out_curr_node;
+			sib = (struct nilfs_btree_node *)bh->b_data;
+			if (nilfs_btree_node_get_nchildren(btree, sib) >
+			    nilfs_btree_node_nchildren_min(btree, sib)) {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_borrow_left;
+				stats->bs_nblocks++;
+				goto out;
+			} else {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_concat_left;
+				stats->bs_nblocks++;
+				/* continue; */
+			}
+		} else if (pindex <
+			   nilfs_btree_node_get_nchildren(btree, parent) - 1) {
+			/* right sibling */
+			sibptr = nilfs_btree_node_get_ptr(btree, parent,
+							  pindex + 1);
+			ret = nilfs_bmap_get_block(&btree->bt_bmap, sibptr,
+						   &bh);
+			if (ret < 0)
+				goto err_out_curr_node;
+			sib = (struct nilfs_btree_node *)bh->b_data;
+			if (nilfs_btree_node_get_nchildren(btree, sib) >
+			    nilfs_btree_node_nchildren_min(btree, sib)) {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_borrow_right;
+				stats->bs_nblocks++;
+				goto out;
+			} else {
+				path[level].bp_sib_bh = bh;
+				path[level].bp_op = nilfs_btree_concat_right;
+				stats->bs_nblocks++;
+				/* continue; */
+			}
+		} else {
+			/* no siblings */
+			/* the only child of the root node */
+			WARN_ON(level != nilfs_btree_height(btree) - 2);
+			if (nilfs_btree_node_get_nchildren(btree, node) - 1 <=
+			    NILFS_BTREE_ROOT_NCHILDREN_MAX) {
+				path[level].bp_op = nilfs_btree_shrink;
+				stats->bs_nblocks += 2;
+			} else {
+				path[level].bp_op = nilfs_btree_do_delete;
+				stats->bs_nblocks++;
+			}
+
+			goto out;
+
+		}
+	}
+
+	node = nilfs_btree_get_root(btree);
+	path[level].bp_oldreq.bpr_ptr =
+		nilfs_btree_node_get_ptr(btree, node, path[level].bp_index);
+	if (btree->bt_bmap.b_pops->bpop_prepare_end_ptr != NULL) {
+		ret = btree->bt_bmap.b_pops->bpop_prepare_end_ptr(
+			&btree->bt_bmap, &path[level].bp_oldreq);
+		if (ret < 0)
+			goto err_out_child_node;
+	}
+	/* child of the root node is deleted */
+	path[level].bp_op = nilfs_btree_do_delete;
+	stats->bs_nblocks++;
+
+	/* success */
+ out:
+	*levelp = level;
+	return ret;
+
+	/* error */
+ err_out_curr_node:
+	if (btree->bt_bmap.b_pops->bpop_abort_end_ptr != NULL)
+		btree->bt_bmap.b_pops->bpop_abort_end_ptr(
+			&btree->bt_bmap, &path[level].bp_oldreq);
+ err_out_child_node:
+	for (level--; level >= NILFS_BTREE_LEVEL_NODE_MIN; level--) {
+		nilfs_bmap_put_block(&btree->bt_bmap, path[level].bp_sib_bh);
+		if (btree->bt_bmap.b_pops->bpop_abort_end_ptr != NULL)
+			btree->bt_bmap.b_pops->bpop_abort_end_ptr(
+				&btree->bt_bmap, &path[level].bp_oldreq);
+	}
+	*levelp = level;
+	stats->bs_nblocks = 0;
+	return ret;
+}
+
+static void nilfs_btree_commit_delete(struct nilfs_btree *btree,
+				      struct nilfs_btree_path *path,
+				      int maxlevel)
+{
+	int level;
+
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
+		if (btree->bt_bmap.b_pops->bpop_commit_end_ptr != NULL)
+			btree->bt_bmap.b_pops->bpop_commit_end_ptr(
+				&btree->bt_bmap, &path[level].bp_oldreq);
+		path[level].bp_op(btree, path, level, NULL, NULL);
+	}
+
+	if (!nilfs_bmap_dirty(&btree->bt_bmap))
+		nilfs_bmap_set_dirty(&btree->bt_bmap);
+}
+
+static int nilfs_btree_delete(struct nilfs_bmap *bmap, __u64 key)
+
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	struct nilfs_bmap_stats stats;
+	int level, ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
+				    NILFS_BTREE_LEVEL_NODE_MIN);
+	if (ret < 0)
+		goto out;
+
+	ret = nilfs_btree_prepare_delete(btree, path, &level, &stats);
+	if (ret < 0)
+		goto out;
+	nilfs_btree_commit_delete(btree, path, level);
+	nilfs_bmap_sub_blocks(bmap, stats.bs_nblocks);
+
+out:
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+	return ret;
+}
+
+static int nilfs_btree_last_key(const struct nilfs_bmap *bmap, __u64 *keyp)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	int ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	ret = nilfs_btree_do_lookup_last(btree, path, keyp, NULL);
+
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+
+	return ret;
+}
+
+static int nilfs_btree_check_delete(struct nilfs_bmap *bmap, __u64 key)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree *btree;
+	struct nilfs_btree_node *root, *node;
+	__u64 maxkey, nextmaxkey;
+	__u64 ptr;
+	int nchildren, ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	root = nilfs_btree_get_root(btree);
+	switch (nilfs_btree_height(btree)) {
+	case 2:
+		bh = NULL;
+		node = root;
+		break;
+	case 3:
+		nchildren = nilfs_btree_node_get_nchildren(btree, root);
+		if (nchildren > 1)
+			return 0;
+		ptr = nilfs_btree_node_get_ptr(btree, root, nchildren - 1);
+		ret = nilfs_bmap_get_block(bmap, ptr, &bh);
+		if (ret < 0)
+			return ret;
+		node = (struct nilfs_btree_node *)bh->b_data;
+		break;
+	default:
+		return 0;
+	}
+
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	maxkey = nilfs_btree_node_get_key(btree, node, nchildren - 1);
+	nextmaxkey = (nchildren > 1) ?
+		nilfs_btree_node_get_key(btree, node, nchildren - 2) : 0;
+	if (bh != NULL)
+		nilfs_bmap_put_block(bmap, bh);
+
+	return (maxkey == key) && (nextmaxkey < bmap->b_low);
+}
+
+static int nilfs_btree_gather_data(struct nilfs_bmap *bmap,
+				   __u64 *keys, __u64 *ptrs, int nitems)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree *btree;
+	struct nilfs_btree_node *node, *root;
+	__le64 *dkeys;
+	__le64 *dptrs;
+	__u64 ptr;
+	int nchildren, i, ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	root = nilfs_btree_get_root(btree);
+	switch (nilfs_btree_height(btree)) {
+	case 2:
+		bh = NULL;
+		node = root;
+		break;
+	case 3:
+		nchildren = nilfs_btree_node_get_nchildren(btree, root);
+		WARN_ON(nchildren > 1);
+		ptr = nilfs_btree_node_get_ptr(btree, root, nchildren - 1);
+		ret = nilfs_bmap_get_block(bmap, ptr, &bh);
+		if (ret < 0)
+			return ret;
+		node = (struct nilfs_btree_node *)bh->b_data;
+		break;
+	default:
+		node = NULL;
+		return -EINVAL;
+	}
+
+	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	if (nchildren < nitems)
+		nitems = nchildren;
+	dkeys = nilfs_btree_node_dkeys(btree, node);
+	dptrs = nilfs_btree_node_dptrs(btree, node);
+	for (i = 0; i < nitems; i++) {
+		keys[i] = nilfs_bmap_dkey_to_key(dkeys[i]);
+		ptrs[i] = nilfs_bmap_dptr_to_ptr(dptrs[i]);
+	}
+
+	if (bh != NULL)
+		nilfs_bmap_put_block(bmap, bh);
+
+	return nitems;
+}
+
+static int
+nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *bmap, __u64 key,
+				       union nilfs_bmap_ptr_req *dreq,
+				       union nilfs_bmap_ptr_req *nreq,
+				       struct buffer_head **bhp,
+				       struct nilfs_bmap_stats *stats)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree *btree;
+	int ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	stats->bs_nblocks = 0;
+
+	/* for data */
+	/* cannot find near ptr */
+	if (btree->bt_ops->btop_find_target != NULL)
+		dreq->bpr_ptr
+			= btree->bt_ops->btop_find_target(btree, NULL, key);
+	ret = bmap->b_pops->bpop_prepare_alloc_ptr(bmap, dreq);
+	if (ret < 0)
+		return ret;
+
+	*bhp = NULL;
+	stats->bs_nblocks++;
+	if (nreq != NULL) {
+		nreq->bpr_ptr = dreq->bpr_ptr + 1;
+		ret = bmap->b_pops->bpop_prepare_alloc_ptr(bmap, nreq);
+		if (ret < 0)
+			goto err_out_dreq;
+
+		ret = nilfs_bmap_get_new_block(bmap, nreq->bpr_ptr, &bh);
+		if (ret < 0)
+			goto err_out_nreq;
+
+		*bhp = bh;
+		stats->bs_nblocks++;
+	}
+
+	/* success */
+	return 0;
+
+	/* error */
+ err_out_nreq:
+	bmap->b_pops->bpop_abort_alloc_ptr(bmap, nreq);
+ err_out_dreq:
+	bmap->b_pops->bpop_abort_alloc_ptr(bmap, dreq);
+	stats->bs_nblocks = 0;
+	return ret;
+
+}
+
+static void
+nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *bmap,
+				      __u64 key, __u64 ptr,
+				      const __u64 *keys, const __u64 *ptrs,
+				      int n, __u64 low, __u64 high,
+				      union nilfs_bmap_ptr_req *dreq,
+				      union nilfs_bmap_ptr_req *nreq,
+				      struct buffer_head *bh)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_node *node;
+	__u64 tmpptr;
+
+	/* free resources */
+	if (bmap->b_ops->bop_clear != NULL)
+		bmap->b_ops->bop_clear(bmap);
+
+	/* ptr must be a pointer to a buffer head. */
+	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
+
+	/* convert and insert */
+	btree = (struct nilfs_btree *)bmap;
+	nilfs_btree_init(bmap, low, high);
+	if (nreq != NULL) {
+		if (bmap->b_pops->bpop_commit_alloc_ptr != NULL) {
+			bmap->b_pops->bpop_commit_alloc_ptr(bmap, dreq);
+			bmap->b_pops->bpop_commit_alloc_ptr(bmap, nreq);
+		}
+
+		/* create child node at level 1 */
+		lock_buffer(bh);
+		node = (struct nilfs_btree_node *)bh->b_data;
+		nilfs_btree_node_init(btree, node, 0, 1, n, keys, ptrs);
+		nilfs_btree_node_insert(btree, node,
+					key, dreq->bpr_ptr, n);
+		if (!buffer_dirty(bh))
+			nilfs_btnode_mark_dirty(bh);
+		if (!nilfs_bmap_dirty(bmap))
+			nilfs_bmap_set_dirty(bmap);
+
+		unlock_buffer(bh);
+		nilfs_bmap_put_block(bmap, bh);
+
+		/* create root node at level 2 */
+		node = nilfs_btree_get_root(btree);
+		tmpptr = nreq->bpr_ptr;
+		nilfs_btree_node_init(btree, node, NILFS_BTREE_NODE_ROOT,
+				      2, 1, &keys[0], &tmpptr);
+	} else {
+		if (bmap->b_pops->bpop_commit_alloc_ptr != NULL)
+			bmap->b_pops->bpop_commit_alloc_ptr(bmap, dreq);
+
+		/* create root node at level 1 */
+		node = nilfs_btree_get_root(btree);
+		nilfs_btree_node_init(btree, node, NILFS_BTREE_NODE_ROOT,
+				      1, n, keys, ptrs);
+		nilfs_btree_node_insert(btree, node,
+					key, dreq->bpr_ptr, n);
+		if (!nilfs_bmap_dirty(bmap))
+			nilfs_bmap_set_dirty(bmap);
+	}
+
+	if (btree->bt_ops->btop_set_target != NULL)
+		btree->bt_ops->btop_set_target(btree, key, dreq->bpr_ptr);
+}
+
+/**
+ * nilfs_btree_convert_and_insert -
+ * @bmap:
+ * @key:
+ * @ptr:
+ * @keys:
+ * @ptrs:
+ * @n:
+ * @low:
+ * @high:
+ */
+int nilfs_btree_convert_and_insert(struct nilfs_bmap *bmap,
+				   __u64 key, __u64 ptr,
+				   const __u64 *keys, const __u64 *ptrs,
+				   int n, __u64 low, __u64 high)
+{
+	struct buffer_head *bh;
+	union nilfs_bmap_ptr_req dreq, nreq, *di, *ni;
+	struct nilfs_bmap_stats stats;
+	int ret;
+
+	if (n + 1 <= NILFS_BTREE_ROOT_NCHILDREN_MAX) {
+		di = &dreq;
+		ni = NULL;
+	} else if ((n + 1) <= NILFS_BTREE_NODE_NCHILDREN_MAX(
+			   1 << bmap->b_inode->i_blkbits)) {
+		di = &dreq;
+		ni = &nreq;
+	} else {
+		di = NULL;
+		ni = NULL;
+		BUG();
+	}
+
+	ret = nilfs_btree_prepare_convert_and_insert(bmap, key, di, ni, &bh,
+						     &stats);
+	if (ret < 0)
+		return ret;
+	nilfs_btree_commit_convert_and_insert(bmap, key, ptr, keys, ptrs, n,
+					      low, high, di, ni, bh);
+	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
+	return 0;
+}
+
+static int nilfs_btree_propagate_p(struct nilfs_btree *btree,
+				   struct nilfs_btree_path *path,
+				   int level,
+				   struct buffer_head *bh)
+{
+	while ((++level < nilfs_btree_height(btree) - 1) &&
+	       !buffer_dirty(path[level].bp_bh))
+		nilfs_btnode_mark_dirty(path[level].bp_bh);
+
+	return 0;
+}
+
+static int nilfs_btree_prepare_update_v(struct nilfs_btree *btree,
+					struct nilfs_btree_path *path,
+					int level)
+{
+	struct nilfs_btree_node *parent;
+	int ret;
+
+	parent = nilfs_btree_get_node(btree, path, level + 1);
+	path[level].bp_oldreq.bpr_ptr =
+		nilfs_btree_node_get_ptr(btree, parent,
+					 path[level + 1].bp_index);
+	path[level].bp_newreq.bpr_ptr = path[level].bp_oldreq.bpr_ptr + 1;
+	ret = nilfs_bmap_prepare_update(&btree->bt_bmap,
+					&path[level].bp_oldreq,
+					&path[level].bp_newreq);
+	if (ret < 0)
+		return ret;
+
+	if (buffer_nilfs_node(path[level].bp_bh)) {
+		path[level].bp_ctxt.oldkey = path[level].bp_oldreq.bpr_ptr;
+		path[level].bp_ctxt.newkey = path[level].bp_newreq.bpr_ptr;
+		path[level].bp_ctxt.bh = path[level].bp_bh;
+		ret = nilfs_btnode_prepare_change_key(
+			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
+			&path[level].bp_ctxt);
+		if (ret < 0) {
+			nilfs_bmap_abort_update(&btree->bt_bmap,
+						&path[level].bp_oldreq,
+						&path[level].bp_newreq);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void nilfs_btree_commit_update_v(struct nilfs_btree *btree,
+					struct nilfs_btree_path *path,
+					int level)
+{
+	struct nilfs_btree_node *parent;
+
+	nilfs_bmap_commit_update(&btree->bt_bmap,
+				 &path[level].bp_oldreq,
+				 &path[level].bp_newreq);
+
+	if (buffer_nilfs_node(path[level].bp_bh)) {
+		nilfs_btnode_commit_change_key(
+			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
+			&path[level].bp_ctxt);
+		path[level].bp_bh = path[level].bp_ctxt.bh;
+	}
+	set_buffer_nilfs_volatile(path[level].bp_bh);
+
+	parent = nilfs_btree_get_node(btree, path, level + 1);
+	nilfs_btree_node_set_ptr(btree, parent, path[level + 1].bp_index,
+				 path[level].bp_newreq.bpr_ptr);
+}
+
+static void nilfs_btree_abort_update_v(struct nilfs_btree *btree,
+				       struct nilfs_btree_path *path,
+				       int level)
+{
+	nilfs_bmap_abort_update(&btree->bt_bmap,
+				&path[level].bp_oldreq,
+				&path[level].bp_newreq);
+	if (buffer_nilfs_node(path[level].bp_bh))
+		nilfs_btnode_abort_change_key(
+			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
+			&path[level].bp_ctxt);
+}
+
+static int nilfs_btree_prepare_propagate_v(struct nilfs_btree *btree,
+					   struct nilfs_btree_path *path,
+					   int minlevel,
+					   int *maxlevelp)
+{
+	int level, ret;
+
+	level = minlevel;
+	if (!buffer_nilfs_volatile(path[level].bp_bh)) {
+		ret = nilfs_btree_prepare_update_v(btree, path, level);
+		if (ret < 0)
+			return ret;
+	}
+	while ((++level < nilfs_btree_height(btree) - 1) &&
+	       !buffer_dirty(path[level].bp_bh)) {
+
+		WARN_ON(buffer_nilfs_volatile(path[level].bp_bh));
+		ret = nilfs_btree_prepare_update_v(btree, path, level);
+		if (ret < 0)
+			goto out;
+	}
+
+	/* success */
+	*maxlevelp = level - 1;
+	return 0;
+
+	/* error */
+ out:
+	while (--level > minlevel)
+		nilfs_btree_abort_update_v(btree, path, level);
+	if (!buffer_nilfs_volatile(path[level].bp_bh))
+		nilfs_btree_abort_update_v(btree, path, level);
+	return ret;
+}
+
+static void nilfs_btree_commit_propagate_v(struct nilfs_btree *btree,
+					   struct nilfs_btree_path *path,
+					   int minlevel,
+					   int maxlevel,
+					   struct buffer_head *bh)
+{
+	int level;
+
+	if (!buffer_nilfs_volatile(path[minlevel].bp_bh))
+		nilfs_btree_commit_update_v(btree, path, minlevel);
+
+	for (level = minlevel + 1; level <= maxlevel; level++)
+		nilfs_btree_commit_update_v(btree, path, level);
+}
+
+static int nilfs_btree_propagate_v(struct nilfs_btree *btree,
+				   struct nilfs_btree_path *path,
+				   int level,
+				   struct buffer_head *bh)
+{
+	int maxlevel, ret;
+	struct nilfs_btree_node *parent;
+	__u64 ptr;
+
+	get_bh(bh);
+	path[level].bp_bh = bh;
+	ret = nilfs_btree_prepare_propagate_v(btree, path, level, &maxlevel);
+	if (ret < 0)
+		goto out;
+
+	if (buffer_nilfs_volatile(path[level].bp_bh)) {
+		parent = nilfs_btree_get_node(btree, path, level + 1);
+		ptr = nilfs_btree_node_get_ptr(btree, parent,
+					       path[level + 1].bp_index);
+		ret = nilfs_bmap_mark_dirty(&btree->bt_bmap, ptr);
+		if (ret < 0)
+			goto out;
+	}
+
+	nilfs_btree_commit_propagate_v(btree, path, level, maxlevel, bh);
+
+ out:
+	brelse(path[level].bp_bh);
+	path[level].bp_bh = NULL;
+	return ret;
+}
+
+static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
+				 struct buffer_head *bh)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	struct nilfs_btree_node *node;
+	__u64 key;
+	int level, ret;
+
+	WARN_ON(!buffer_dirty(bh));
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	if (buffer_nilfs_node(bh)) {
+		node = (struct nilfs_btree_node *)bh->b_data;
+		key = nilfs_btree_node_get_key(btree, node, 0);
+		level = nilfs_btree_node_get_level(btree, node);
+	} else {
+		key = nilfs_bmap_data_get_key(bmap, bh);
+		level = NILFS_BTREE_LEVEL_DATA;
+	}
+
+	ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1);
+	if (ret < 0) {
+		if (unlikely(ret == -ENOENT))
+			printk(KERN_CRIT "%s: key = %llu, level == %d\n",
+			       __func__, (unsigned long long)key, level);
+		goto out;
+	}
+
+	ret = btree->bt_ops->btop_propagate(btree, path, level, bh);
+
+ out:
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+
+	return ret;
+}
+
+static int nilfs_btree_propagate_gc(const struct nilfs_bmap *bmap,
+				    struct buffer_head *bh)
+{
+	return nilfs_bmap_mark_dirty(bmap, bh->b_blocknr);
+}
+
+static void nilfs_btree_add_dirty_buffer(struct nilfs_btree *btree,
+					 struct list_head *lists,
+					 struct buffer_head *bh)
+{
+	struct list_head *head;
+	struct buffer_head *cbh;
+	struct nilfs_btree_node *node, *cnode;
+	__u64 key, ckey;
+	int level;
+
+	get_bh(bh);
+	node = (struct nilfs_btree_node *)bh->b_data;
+	key = nilfs_btree_node_get_key(btree, node, 0);
+	level = nilfs_btree_node_get_level(btree, node);
+	list_for_each(head, &lists[level]) {
+		cbh = list_entry(head, struct buffer_head, b_assoc_buffers);
+		cnode = (struct nilfs_btree_node *)cbh->b_data;
+		ckey = nilfs_btree_node_get_key(btree, cnode, 0);
+		if (key < ckey)
+			break;
+	}
+	list_add_tail(&bh->b_assoc_buffers, head);
+}
+
+static void nilfs_btree_lookup_dirty_buffers(struct nilfs_bmap *bmap,
+					     struct list_head *listp)
+{
+	struct nilfs_btree *btree = (struct nilfs_btree *)bmap;
+	struct address_space *btcache = &NILFS_BMAP_I(bmap)->i_btnode_cache;
+	struct list_head lists[NILFS_BTREE_LEVEL_MAX];
+	struct pagevec pvec;
+	struct buffer_head *bh, *head;
+	pgoff_t index = 0;
+	int level, i;
+
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
+	     level < NILFS_BTREE_LEVEL_MAX;
+	     level++)
+		INIT_LIST_HEAD(&lists[level]);
+
+	pagevec_init(&pvec, 0);
+
+	while (pagevec_lookup_tag(&pvec, btcache, &index, PAGECACHE_TAG_DIRTY,
+				  PAGEVEC_SIZE)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			bh = head = page_buffers(pvec.pages[i]);
+			do {
+				if (buffer_dirty(bh))
+					nilfs_btree_add_dirty_buffer(btree,
+								     lists, bh);
+			} while ((bh = bh->b_this_page) != head);
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+
+	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
+	     level < NILFS_BTREE_LEVEL_MAX;
+	     level++)
+		list_splice(&lists[level], listp->prev);
+}
+
+static int nilfs_btree_assign_p(struct nilfs_btree *btree,
+				struct nilfs_btree_path *path,
+				int level,
+				struct buffer_head **bh,
+				sector_t blocknr,
+				union nilfs_binfo *binfo)
+{
+	struct nilfs_btree_node *parent;
+	__u64 key;
+	__u64 ptr;
+	int ret;
+
+	parent = nilfs_btree_get_node(btree, path, level + 1);
+	ptr = nilfs_btree_node_get_ptr(btree, parent,
+				       path[level + 1].bp_index);
+	if (buffer_nilfs_node(*bh)) {
+		path[level].bp_ctxt.oldkey = ptr;
+		path[level].bp_ctxt.newkey = blocknr;
+		path[level].bp_ctxt.bh = *bh;
+		ret = nilfs_btnode_prepare_change_key(
+			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
+			&path[level].bp_ctxt);
+		if (ret < 0)
+			return ret;
+		nilfs_btnode_commit_change_key(
+			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
+			&path[level].bp_ctxt);
+		*bh = path[level].bp_ctxt.bh;
+	}
+
+	nilfs_btree_node_set_ptr(btree, parent,
+				 path[level + 1].bp_index, blocknr);
+
+	key = nilfs_btree_node_get_key(btree, parent,
+				       path[level + 1].bp_index);
+	/* on-disk format */
+	binfo->bi_dat.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+	binfo->bi_dat.bi_level = level;
+
+	return 0;
+}
+
+static int nilfs_btree_assign_v(struct nilfs_btree *btree,
+				struct nilfs_btree_path *path,
+				int level,
+				struct buffer_head **bh,
+				sector_t blocknr,
+				union nilfs_binfo *binfo)
+{
+	struct nilfs_btree_node *parent;
+	__u64 key;
+	__u64 ptr;
+	union nilfs_bmap_ptr_req req;
+	int ret;
+
+	parent = nilfs_btree_get_node(btree, path, level + 1);
+	ptr = nilfs_btree_node_get_ptr(btree, parent,
+				       path[level + 1].bp_index);
+	req.bpr_ptr = ptr;
+	ret = btree->bt_bmap.b_pops->bpop_prepare_start_ptr(&btree->bt_bmap,
+							       &req);
+	if (ret < 0)
+		return ret;
+	btree->bt_bmap.b_pops->bpop_commit_start_ptr(&btree->bt_bmap,
+							&req, blocknr);
+
+	key = nilfs_btree_node_get_key(btree, parent,
+				       path[level + 1].bp_index);
+	/* on-disk format */
+	binfo->bi_v.bi_vblocknr = nilfs_bmap_ptr_to_dptr(ptr);
+	binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+
+	return 0;
+}
+
+static int nilfs_btree_assign(struct nilfs_bmap *bmap,
+			      struct buffer_head **bh,
+			      sector_t blocknr,
+			      union nilfs_binfo *binfo)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	struct nilfs_btree_node *node;
+	__u64 key;
+	int level, ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	if (buffer_nilfs_node(*bh)) {
+		node = (struct nilfs_btree_node *)(*bh)->b_data;
+		key = nilfs_btree_node_get_key(btree, node, 0);
+		level = nilfs_btree_node_get_level(btree, node);
+	} else {
+		key = nilfs_bmap_data_get_key(bmap, *bh);
+		level = NILFS_BTREE_LEVEL_DATA;
+	}
+
+	ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1);
+	if (ret < 0) {
+		WARN_ON(ret == -ENOENT);
+		goto out;
+	}
+
+	ret = btree->bt_ops->btop_assign(btree, path, level, bh,
+					    blocknr, binfo);
+
+ out:
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+
+	return ret;
+}
+
+static int nilfs_btree_assign_gc(struct nilfs_bmap *bmap,
+				 struct buffer_head **bh,
+				 sector_t blocknr,
+				 union nilfs_binfo *binfo)
+{
+	struct nilfs_btree *btree;
+	struct nilfs_btree_node *node;
+	__u64 key;
+	int ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	ret = nilfs_bmap_move_v(bmap, (*bh)->b_blocknr, blocknr);
+	if (ret < 0)
+		return ret;
+
+	if (buffer_nilfs_node(*bh)) {
+		node = (struct nilfs_btree_node *)(*bh)->b_data;
+		key = nilfs_btree_node_get_key(btree, node, 0);
+	} else
+		key = nilfs_bmap_data_get_key(bmap, *bh);
+
+	/* on-disk format */
+	binfo->bi_v.bi_vblocknr = cpu_to_le64((*bh)->b_blocknr);
+	binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+
+	return 0;
+}
+
+static int nilfs_btree_mark(struct nilfs_bmap *bmap, __u64 key, int level)
+{
+	struct buffer_head *bh;
+	struct nilfs_btree *btree;
+	struct nilfs_btree_path *path;
+	__u64 ptr;
+	int ret;
+
+	btree = (struct nilfs_btree *)bmap;
+	path = nilfs_btree_alloc_path(btree);
+	if (path == NULL)
+		return -ENOMEM;
+	nilfs_btree_init_path(btree, path);
+
+	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level + 1);
+	if (ret < 0) {
+		WARN_ON(ret == -ENOENT);
+		goto out;
+	}
+	ret = nilfs_bmap_get_block(&btree->bt_bmap, ptr, &bh);
+	if (ret < 0) {
+		WARN_ON(ret == -ENOENT);
+		goto out;
+	}
+
+	if (!buffer_dirty(bh))
+		nilfs_btnode_mark_dirty(bh);
+	nilfs_bmap_put_block(&btree->bt_bmap, bh);
+	if (!nilfs_bmap_dirty(&btree->bt_bmap))
+		nilfs_bmap_set_dirty(&btree->bt_bmap);
+
+ out:
+	nilfs_btree_clear_path(btree, path);
+	nilfs_btree_free_path(btree, path);
+	return ret;
+}
+
+static const struct nilfs_bmap_operations nilfs_btree_ops = {
+	.bop_lookup		=	nilfs_btree_lookup,
+	.bop_insert		=	nilfs_btree_insert,
+	.bop_delete		=	nilfs_btree_delete,
+	.bop_clear		=	NULL,
+
+	.bop_propagate		=	nilfs_btree_propagate,
+
+	.bop_lookup_dirty_buffers =	nilfs_btree_lookup_dirty_buffers,
+
+	.bop_assign		=	nilfs_btree_assign,
+	.bop_mark		=	nilfs_btree_mark,
+
+	.bop_last_key		=	nilfs_btree_last_key,
+	.bop_check_insert	=	NULL,
+	.bop_check_delete	=	nilfs_btree_check_delete,
+	.bop_gather_data	=	nilfs_btree_gather_data,
+};
+
+static const struct nilfs_bmap_operations nilfs_btree_ops_gc = {
+	.bop_lookup		=	NULL,
+	.bop_insert		=	NULL,
+	.bop_delete		=	NULL,
+	.bop_clear		=	NULL,
+
+	.bop_propagate		=	nilfs_btree_propagate_gc,
+
+	.bop_lookup_dirty_buffers =	nilfs_btree_lookup_dirty_buffers,
+
+	.bop_assign		=	nilfs_btree_assign_gc,
+	.bop_mark		=	NULL,
+
+	.bop_last_key		=	NULL,
+	.bop_check_insert	=	NULL,
+	.bop_check_delete	=	NULL,
+	.bop_gather_data	=	NULL,
+};
+
+static const struct nilfs_btree_operations nilfs_btree_ops_v = {
+	.btop_find_target	=	nilfs_btree_find_target_v,
+	.btop_set_target	=	nilfs_btree_set_target_v,
+	.btop_propagate		=	nilfs_btree_propagate_v,
+	.btop_assign		=	nilfs_btree_assign_v,
+};
+
+static const struct nilfs_btree_operations nilfs_btree_ops_p = {
+	.btop_find_target	=	NULL,
+	.btop_set_target	=	NULL,
+	.btop_propagate		=	nilfs_btree_propagate_p,
+	.btop_assign		=	nilfs_btree_assign_p,
+};
+
+int nilfs_btree_init(struct nilfs_bmap *bmap, __u64 low, __u64 high)
+{
+	struct nilfs_btree *btree;
+
+	btree = (struct nilfs_btree *)bmap;
+	bmap->b_ops = &nilfs_btree_ops;
+	bmap->b_low = low;
+	bmap->b_high = high;
+	switch (bmap->b_inode->i_ino) {
+	case NILFS_DAT_INO:
+		btree->bt_ops = &nilfs_btree_ops_p;
+		break;
+	default:
+		btree->bt_ops = &nilfs_btree_ops_v;
+		break;
+	}
+
+	return 0;
+}
+
+void nilfs_btree_init_gc(struct nilfs_bmap *bmap)
+{
+	bmap->b_low = NILFS_BMAP_LARGE_LOW;
+	bmap->b_high = NILFS_BMAP_LARGE_HIGH;
+	bmap->b_ops = &nilfs_btree_ops_gc;
+}
diff --git a/fs/nilfs2/btree.h b/fs/nilfs2/btree.h
new file mode 100644
index 00000000000..4766deb52fb
--- /dev/null
+++ b/fs/nilfs2/btree.h
@@ -0,0 +1,117 @@
+/*
+ * btree.h - NILFS B-tree.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_BTREE_H
+#define _NILFS_BTREE_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/list.h>
+#include <linux/nilfs2_fs.h>
+#include "btnode.h"
+#include "bmap.h"
+
+struct nilfs_btree;
+struct nilfs_btree_path;
+
+/**
+ * struct nilfs_btree_operations - B-tree operation table
+ */
+struct nilfs_btree_operations {
+	__u64 (*btop_find_target)(const struct nilfs_btree *,
+				  const struct nilfs_btree_path *, __u64);
+	void (*btop_set_target)(struct nilfs_btree *, __u64, __u64);
+
+	struct the_nilfs *(*btop_get_nilfs)(struct nilfs_btree *);
+
+	int (*btop_propagate)(struct nilfs_btree *,
+			      struct nilfs_btree_path *,
+			      int,
+			      struct buffer_head *);
+	int (*btop_assign)(struct nilfs_btree *,
+			   struct nilfs_btree_path *,
+			   int,
+			   struct buffer_head **,
+			   sector_t,
+			   union nilfs_binfo *);
+};
+
+/**
+ * struct nilfs_btree_node - B-tree node
+ * @bn_flags: flags
+ * @bn_level: level
+ * @bn_nchildren: number of children
+ * @bn_pad: padding
+ */
+struct nilfs_btree_node {
+	__u8 bn_flags;
+	__u8 bn_level;
+	__le16 bn_nchildren;
+	__le32 bn_pad;
+};
+
+/* flags */
+#define NILFS_BTREE_NODE_ROOT	0x01
+
+/* level */
+#define NILFS_BTREE_LEVEL_DATA		0
+#define NILFS_BTREE_LEVEL_NODE_MIN	(NILFS_BTREE_LEVEL_DATA + 1)
+#define NILFS_BTREE_LEVEL_MAX		14
+
+/**
+ * struct nilfs_btree - B-tree structure
+ * @bt_bmap: bmap base structure
+ * @bt_ops: B-tree operation table
+ */
+struct nilfs_btree {
+	struct nilfs_bmap bt_bmap;
+
+	/* B-tree-specific members */
+	const struct nilfs_btree_operations *bt_ops;
+};
+
+
+#define NILFS_BTREE_ROOT_SIZE		NILFS_BMAP_SIZE
+#define NILFS_BTREE_ROOT_NCHILDREN_MAX					\
+	((NILFS_BTREE_ROOT_SIZE - sizeof(struct nilfs_btree_node)) /	\
+	 (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */)))
+#define NILFS_BTREE_ROOT_NCHILDREN_MIN	0
+#define NILFS_BTREE_NODE_EXTRA_PAD_SIZE	(sizeof(__le64))
+#define NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize)			\
+	(((nodesize) - sizeof(struct nilfs_btree_node) -		\
+		NILFS_BTREE_NODE_EXTRA_PAD_SIZE) /			\
+	 (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */)))
+#define NILFS_BTREE_NODE_NCHILDREN_MIN(nodesize)			\
+	((NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) - 1) / 2 + 1)
+#define NILFS_BTREE_KEY_MIN	((__u64)0)
+#define NILFS_BTREE_KEY_MAX	(~(__u64)0)
+
+
+int nilfs_btree_path_cache_init(void);
+void nilfs_btree_path_cache_destroy(void);
+int nilfs_btree_init(struct nilfs_bmap *, __u64, __u64);
+int nilfs_btree_convert_and_insert(struct nilfs_bmap *, __u64, __u64,
+				   const __u64 *, const __u64 *,
+				   int, __u64, __u64);
+void nilfs_btree_init_gc(struct nilfs_bmap *);
+
+#endif	/* _NILFS_BTREE_H */
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
new file mode 100644
index 00000000000..e90b60dfced
--- /dev/null
+++ b/fs/nilfs2/cpfile.c
@@ -0,0 +1,925 @@
+/*
+ * cpfile.c - NILFS checkpoint file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/errno.h>
+#include <linux/nilfs2_fs.h>
+#include "mdt.h"
+#include "cpfile.h"
+
+
+static inline unsigned long
+nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
+{
+	return NILFS_MDT(cpfile)->mi_entries_per_block;
+}
+
+/* block number from the beginning of the file */
+static unsigned long
+nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
+{
+	__u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
+	do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
+	return (unsigned long)tcno;
+}
+
+/* offset in block */
+static unsigned long
+nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
+{
+	__u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
+	return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
+}
+
+static unsigned long
+nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
+				  __u64 curr,
+				  __u64 max)
+{
+	return min_t(__u64,
+		     nilfs_cpfile_checkpoints_per_block(cpfile) -
+		     nilfs_cpfile_get_offset(cpfile, curr),
+		     max - curr);
+}
+
+static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
+					   __u64 cno)
+{
+	return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
+}
+
+static unsigned int
+nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
+					 struct buffer_head *bh,
+					 void *kaddr,
+					 unsigned int n)
+{
+	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	unsigned int count;
+
+	count = le32_to_cpu(cp->cp_checkpoints_count) + n;
+	cp->cp_checkpoints_count = cpu_to_le32(count);
+	return count;
+}
+
+static unsigned int
+nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
+					 struct buffer_head *bh,
+					 void *kaddr,
+					 unsigned int n)
+{
+	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	unsigned int count;
+
+	WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
+	count = le32_to_cpu(cp->cp_checkpoints_count) - n;
+	cp->cp_checkpoints_count = cpu_to_le32(count);
+	return count;
+}
+
+static inline struct nilfs_cpfile_header *
+nilfs_cpfile_block_get_header(const struct inode *cpfile,
+			      struct buffer_head *bh,
+			      void *kaddr)
+{
+	return kaddr + bh_offset(bh);
+}
+
+static struct nilfs_checkpoint *
+nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
+				  struct buffer_head *bh,
+				  void *kaddr)
+{
+	return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
+		NILFS_MDT(cpfile)->mi_entry_size;
+}
+
+static void nilfs_cpfile_block_init(struct inode *cpfile,
+				    struct buffer_head *bh,
+				    void *kaddr)
+{
+	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+	int n = nilfs_cpfile_checkpoints_per_block(cpfile);
+
+	while (n-- > 0) {
+		nilfs_checkpoint_set_invalid(cp);
+		cp = (void *)cp + cpsz;
+	}
+}
+
+static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
+						struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
+}
+
+static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
+						    __u64 cno,
+						    int create,
+						    struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(cpfile,
+				   nilfs_cpfile_get_blkoff(cpfile, cno),
+				   create, nilfs_cpfile_block_init, bhp);
+}
+
+static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
+						       __u64 cno)
+{
+	return nilfs_mdt_delete_block(cpfile,
+				      nilfs_cpfile_get_blkoff(cpfile, cno));
+}
+
+/**
+ * nilfs_cpfile_get_checkpoint - get a checkpoint
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @create: create flag
+ * @cpp: pointer to a checkpoint
+ * @bhp: pointer to a buffer head
+ *
+ * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
+ * specified by @cno. A new checkpoint will be created if @cno is the current
+ * checkpoint number and @create is nonzero.
+ *
+ * Return Value: On success, 0 is returned, and the checkpoint and the
+ * buffer head of the buffer on which the checkpoint is located are stored in
+ * the place pointed by @cpp and @bhp, respectively. On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ *
+ * %-EINVAL - invalid checkpoint.
+ */
+int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
+				__u64 cno,
+				int create,
+				struct nilfs_checkpoint **cpp,
+				struct buffer_head **bhp)
+{
+	struct buffer_head *header_bh, *cp_bh;
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	void *kaddr;
+	int ret;
+
+	if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
+		     (cno < nilfs_mdt_cno(cpfile) && create)))
+		return -EINVAL;
+
+	down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
+	if (ret < 0)
+		goto out_header;
+	kaddr = kmap(cp_bh->b_page);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	if (nilfs_checkpoint_invalid(cp)) {
+		if (!create) {
+			kunmap(cp_bh->b_page);
+			brelse(cp_bh);
+			ret = -ENOENT;
+			goto out_header;
+		}
+		/* a newly-created checkpoint */
+		nilfs_checkpoint_clear_invalid(cp);
+		if (!nilfs_cpfile_is_in_first(cpfile, cno))
+			nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
+								 kaddr, 1);
+		nilfs_mdt_mark_buffer_dirty(cp_bh);
+
+		kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+		header = nilfs_cpfile_block_get_header(cpfile, header_bh,
+						       kaddr);
+		le64_add_cpu(&header->ch_ncheckpoints, 1);
+		kunmap_atomic(kaddr, KM_USER0);
+		nilfs_mdt_mark_buffer_dirty(header_bh);
+		nilfs_mdt_mark_dirty(cpfile);
+	}
+
+	if (cpp != NULL)
+		*cpp = cp;
+	*bhp = cp_bh;
+
+ out_header:
+	brelse(header_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_cpfile_put_checkpoint - put a checkpoint
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @bh: buffer head
+ *
+ * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
+ * specified by @cno. @bh must be the buffer head which has been returned by
+ * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
+ */
+void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
+				 struct buffer_head *bh)
+{
+	kunmap(bh->b_page);
+	brelse(bh);
+}
+
+/**
+ * nilfs_cpfile_delete_checkpoints - delete checkpoints
+ * @cpfile: inode of checkpoint file
+ * @start: start checkpoint number
+ * @end: end checkpoint numer
+ *
+ * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
+ * the period from @start to @end, excluding @end itself. The checkpoints
+ * which have been already deleted are ignored.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EINVAL - invalid checkpoints.
+ */
+int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
+				    __u64 start,
+				    __u64 end)
+{
+	struct buffer_head *header_bh, *cp_bh;
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+	__u64 cno;
+	void *kaddr;
+	unsigned long tnicps;
+	int ret, ncps, nicps, count, i;
+
+	if (unlikely(start == 0 || start > end)) {
+		printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
+		       "[%llu, %llu)\n", __func__,
+		       (unsigned long long)start, (unsigned long long)end);
+		return -EINVAL;
+	}
+
+	/* cannot delete the latest checkpoint */
+	if (start == nilfs_mdt_cno(cpfile) - 1)
+		return -EPERM;
+
+	down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+	tnicps = 0;
+
+	for (cno = start; cno < end; cno += ncps) {
+		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
+		ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				goto out_sem;
+			/* skip hole */
+			ret = 0;
+			continue;
+		}
+
+		kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
+		cp = nilfs_cpfile_block_get_checkpoint(
+			cpfile, cno, cp_bh, kaddr);
+		nicps = 0;
+		for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
+			WARN_ON(nilfs_checkpoint_snapshot(cp));
+			if (!nilfs_checkpoint_invalid(cp)) {
+				nilfs_checkpoint_set_invalid(cp);
+				nicps++;
+			}
+		}
+		if (nicps > 0) {
+			tnicps += nicps;
+			nilfs_mdt_mark_buffer_dirty(cp_bh);
+			nilfs_mdt_mark_dirty(cpfile);
+			if (!nilfs_cpfile_is_in_first(cpfile, cno) &&
+			    (count = nilfs_cpfile_block_sub_valid_checkpoints(
+				    cpfile, cp_bh, kaddr, nicps)) == 0) {
+				/* make hole */
+				kunmap_atomic(kaddr, KM_USER0);
+				brelse(cp_bh);
+				ret = nilfs_cpfile_delete_checkpoint_block(
+					cpfile, cno);
+				if (ret == 0)
+					continue;
+				printk(KERN_ERR "%s: cannot delete block\n",
+				       __func__);
+				goto out_sem;
+			}
+		}
+
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(cp_bh);
+	}
+
+	if (tnicps > 0) {
+		kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+		header = nilfs_cpfile_block_get_header(cpfile, header_bh,
+						       kaddr);
+		le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
+		nilfs_mdt_mark_buffer_dirty(header_bh);
+		nilfs_mdt_mark_dirty(cpfile);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+	brelse(header_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
+					      struct nilfs_checkpoint *cp,
+					      struct nilfs_cpinfo *ci)
+{
+	ci->ci_flags = le32_to_cpu(cp->cp_flags);
+	ci->ci_cno = le64_to_cpu(cp->cp_cno);
+	ci->ci_create = le64_to_cpu(cp->cp_create);
+	ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
+	ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
+	ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
+	ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
+}
+
+static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
+					  struct nilfs_cpinfo *ci, size_t nci)
+{
+	struct nilfs_checkpoint *cp;
+	struct buffer_head *bh;
+	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+	__u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
+	void *kaddr;
+	int n, ret;
+	int ncps, i;
+
+	if (cno == 0)
+		return -ENOENT; /* checkpoint number 0 is invalid */
+	down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+	for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
+		ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
+		ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				goto out;
+			continue; /* skip hole */
+		}
+
+		kaddr = kmap_atomic(bh->b_page, KM_USER0);
+		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+		for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
+			if (!nilfs_checkpoint_invalid(cp))
+				nilfs_cpfile_checkpoint_to_cpinfo(
+					cpfile, cp, &ci[n++]);
+		}
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(bh);
+	}
+
+	ret = n;
+	if (n > 0)
+		*cnop = ci[n - 1].ci_cno + 1;
+
+ out:
+	up_read(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
+					  struct nilfs_cpinfo *ci, size_t nci)
+{
+	struct buffer_head *bh;
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	__u64 curr = *cnop, next;
+	unsigned long curr_blkoff, next_blkoff;
+	void *kaddr;
+	int n = 0, ret;
+
+	down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+	if (curr == 0) {
+		ret = nilfs_cpfile_get_header_block(cpfile, &bh);
+		if (ret < 0)
+			goto out;
+		kaddr = kmap_atomic(bh->b_page, KM_USER0);
+		header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+		curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(bh);
+		if (curr == 0) {
+			ret = 0;
+			goto out;
+		}
+	} else if (unlikely(curr == ~(__u64)0)) {
+		ret = 0;
+		goto out;
+	}
+
+	curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
+	ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
+	if (unlikely(ret < 0)) {
+		if (ret == -ENOENT)
+			ret = 0; /* No snapshots (started from a hole block) */
+		goto out;
+	}
+	kaddr = kmap_atomic(bh->b_page, KM_USER0);
+	while (n < nci) {
+		cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
+		curr = ~(__u64)0; /* Terminator */
+		if (unlikely(nilfs_checkpoint_invalid(cp) ||
+			     !nilfs_checkpoint_snapshot(cp)))
+			break;
+		nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, &ci[n++]);
+		next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
+		if (next == 0)
+			break; /* reach end of the snapshot list */
+
+		next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
+		if (curr_blkoff != next_blkoff) {
+			kunmap_atomic(kaddr, KM_USER0);
+			brelse(bh);
+			ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
+								0, &bh);
+			if (unlikely(ret < 0)) {
+				WARN_ON(ret == -ENOENT);
+				goto out;
+			}
+			kaddr = kmap_atomic(bh->b_page, KM_USER0);
+		}
+		curr = next;
+		curr_blkoff = next_blkoff;
+	}
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(bh);
+	*cnop = curr;
+	ret = n;
+
+ out:
+	up_read(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_cpfile_get_cpinfo -
+ * @cpfile:
+ * @cno:
+ * @ci:
+ * @nci:
+ */
+
+ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
+				struct nilfs_cpinfo *ci, size_t nci)
+{
+	switch (mode) {
+	case NILFS_CHECKPOINT:
+		return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, ci, nci);
+	case NILFS_SNAPSHOT:
+		return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, ci, nci);
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * nilfs_cpfile_delete_checkpoint -
+ * @cpfile:
+ * @cno:
+ */
+int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
+{
+	struct nilfs_cpinfo ci;
+	__u64 tcno = cno;
+	ssize_t nci;
+	int ret;
+
+	nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, 1);
+	if (nci < 0)
+		return nci;
+	else if (nci == 0 || ci.ci_cno != cno)
+		return -ENOENT;
+
+	/* cannot delete the latest checkpoint nor snapshots */
+	ret = nilfs_cpinfo_snapshot(&ci);
+	if (ret < 0)
+		return ret;
+	else if (ret > 0 || cno == nilfs_mdt_cno(cpfile) - 1)
+		return -EPERM;
+
+	return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
+}
+
+static struct nilfs_snapshot_list *
+nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
+				     __u64 cno,
+				     struct buffer_head *bh,
+				     void *kaddr)
+{
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	struct nilfs_snapshot_list *list;
+
+	if (cno != 0) {
+		cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+		list = &cp->cp_snapshot_list;
+	} else {
+		header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+		list = &header->ch_snapshot_list;
+	}
+	return list;
+}
+
+static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
+{
+	struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	struct nilfs_snapshot_list *list;
+	__u64 curr, prev;
+	unsigned long curr_blkoff, prev_blkoff;
+	void *kaddr;
+	int ret;
+
+	if (cno == 0)
+		return -ENOENT; /* checkpoint number 0 is invalid */
+	down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+	if (ret < 0)
+		goto out_sem;
+	kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	if (nilfs_checkpoint_invalid(cp)) {
+		ret = -ENOENT;
+		kunmap_atomic(kaddr, KM_USER0);
+		goto out_cp;
+	}
+	if (nilfs_checkpoint_snapshot(cp)) {
+		ret = 0;
+		kunmap_atomic(kaddr, KM_USER0);
+		goto out_cp;
+	}
+	kunmap_atomic(kaddr, KM_USER0);
+
+	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+	if (ret < 0)
+		goto out_cp;
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+	list = &header->ch_snapshot_list;
+	curr_bh = header_bh;
+	get_bh(curr_bh);
+	curr = 0;
+	curr_blkoff = 0;
+	prev = le64_to_cpu(list->ssl_prev);
+	while (prev > cno) {
+		prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
+		curr = prev;
+		if (curr_blkoff != prev_blkoff) {
+			kunmap_atomic(kaddr, KM_USER0);
+			brelse(curr_bh);
+			ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
+								0, &curr_bh);
+			if (ret < 0)
+				goto out_header;
+			kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
+		}
+		curr_blkoff = prev_blkoff;
+		cp = nilfs_cpfile_block_get_checkpoint(
+			cpfile, curr, curr_bh, kaddr);
+		list = &cp->cp_snapshot_list;
+		prev = le64_to_cpu(list->ssl_prev);
+	}
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (prev != 0) {
+		ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
+							&prev_bh);
+		if (ret < 0)
+			goto out_curr;
+	} else {
+		prev_bh = header_bh;
+		get_bh(prev_bh);
+	}
+
+	kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
+	list = nilfs_cpfile_block_get_snapshot_list(
+		cpfile, curr, curr_bh, kaddr);
+	list->ssl_prev = cpu_to_le64(cno);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
+	cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
+	nilfs_checkpoint_set_snapshot(cp);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
+	list = nilfs_cpfile_block_get_snapshot_list(
+		cpfile, prev, prev_bh, kaddr);
+	list->ssl_next = cpu_to_le64(cno);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+	le64_add_cpu(&header->ch_nsnapshots, 1);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_mdt_mark_buffer_dirty(prev_bh);
+	nilfs_mdt_mark_buffer_dirty(curr_bh);
+	nilfs_mdt_mark_buffer_dirty(cp_bh);
+	nilfs_mdt_mark_buffer_dirty(header_bh);
+	nilfs_mdt_mark_dirty(cpfile);
+
+	brelse(prev_bh);
+
+ out_curr:
+	brelse(curr_bh);
+
+ out_header:
+	brelse(header_bh);
+
+ out_cp:
+	brelse(cp_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
+{
+	struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
+	struct nilfs_cpfile_header *header;
+	struct nilfs_checkpoint *cp;
+	struct nilfs_snapshot_list *list;
+	__u64 next, prev;
+	void *kaddr;
+	int ret;
+
+	if (cno == 0)
+		return -ENOENT; /* checkpoint number 0 is invalid */
+	down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+	if (ret < 0)
+		goto out_sem;
+	kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	if (nilfs_checkpoint_invalid(cp)) {
+		ret = -ENOENT;
+		kunmap_atomic(kaddr, KM_USER0);
+		goto out_cp;
+	}
+	if (!nilfs_checkpoint_snapshot(cp)) {
+		ret = 0;
+		kunmap_atomic(kaddr, KM_USER0);
+		goto out_cp;
+	}
+
+	list = &cp->cp_snapshot_list;
+	next = le64_to_cpu(list->ssl_next);
+	prev = le64_to_cpu(list->ssl_prev);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+	if (ret < 0)
+		goto out_cp;
+	if (next != 0) {
+		ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
+							&next_bh);
+		if (ret < 0)
+			goto out_header;
+	} else {
+		next_bh = header_bh;
+		get_bh(next_bh);
+	}
+	if (prev != 0) {
+		ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
+							&prev_bh);
+		if (ret < 0)
+			goto out_next;
+	} else {
+		prev_bh = header_bh;
+		get_bh(prev_bh);
+	}
+
+	kaddr = kmap_atomic(next_bh->b_page, KM_USER0);
+	list = nilfs_cpfile_block_get_snapshot_list(
+		cpfile, next, next_bh, kaddr);
+	list->ssl_prev = cpu_to_le64(prev);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
+	list = nilfs_cpfile_block_get_snapshot_list(
+		cpfile, prev, prev_bh, kaddr);
+	list->ssl_next = cpu_to_le64(next);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+	cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
+	cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
+	nilfs_checkpoint_clear_snapshot(cp);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+	le64_add_cpu(&header->ch_nsnapshots, -1);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_mdt_mark_buffer_dirty(next_bh);
+	nilfs_mdt_mark_buffer_dirty(prev_bh);
+	nilfs_mdt_mark_buffer_dirty(cp_bh);
+	nilfs_mdt_mark_buffer_dirty(header_bh);
+	nilfs_mdt_mark_dirty(cpfile);
+
+	brelse(prev_bh);
+
+ out_next:
+	brelse(next_bh);
+
+ out_header:
+	brelse(header_bh);
+
+ out_cp:
+	brelse(cp_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_cpfile_is_snapshot -
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ *
+ * Description:
+ *
+ * Return Value: On success, 1 is returned if the checkpoint specified by
+ * @cno is a snapshot, or 0 if not. On error, one of the following negative
+ * error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ */
+int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
+{
+	struct buffer_head *bh;
+	struct nilfs_checkpoint *cp;
+	void *kaddr;
+	int ret;
+
+	if (cno == 0)
+		return -ENOENT; /* checkpoint number 0 is invalid */
+	down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
+	if (ret < 0)
+		goto out;
+	kaddr = kmap_atomic(bh->b_page, KM_USER0);
+	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+	ret = nilfs_checkpoint_snapshot(cp);
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(bh);
+
+ out:
+	up_read(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_cpfile_change_cpmode - change checkpoint mode
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @status: mode of checkpoint
+ *
+ * Description: nilfs_change_cpmode() changes the mode of the checkpoint
+ * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ */
+int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
+{
+	struct the_nilfs *nilfs;
+	int ret;
+
+	nilfs = NILFS_MDT(cpfile)->mi_nilfs;
+
+	switch (mode) {
+	case NILFS_CHECKPOINT:
+		/*
+		 * Check for protecting existing snapshot mounts:
+		 * bd_mount_sem is used to make this operation atomic and
+		 * exclusive with a new mount job.  Though it doesn't cover
+		 * umount, it's enough for the purpose.
+		 */
+		down(&nilfs->ns_bdev->bd_mount_sem);
+		if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
+			/* Current implementation does not have to protect
+			   plain read-only mounts since they are exclusive
+			   with a read/write mount and are protected from the
+			   cleaner. */
+			ret = -EBUSY;
+		} else
+			ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
+		up(&nilfs->ns_bdev->bd_mount_sem);
+		return ret;
+	case NILFS_SNAPSHOT:
+		return nilfs_cpfile_set_snapshot(cpfile, cno);
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * nilfs_cpfile_get_stat - get checkpoint statistics
+ * @cpfile: inode of checkpoint file
+ * @stat: pointer to a structure of checkpoint statistics
+ *
+ * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
+ *
+ * Return Value: On success, 0 is returned, and checkpoints information is
+ * stored in the place pointed by @stat. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
+{
+	struct buffer_head *bh;
+	struct nilfs_cpfile_header *header;
+	void *kaddr;
+	int ret;
+
+	down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+	ret = nilfs_cpfile_get_header_block(cpfile, &bh);
+	if (ret < 0)
+		goto out_sem;
+	kaddr = kmap_atomic(bh->b_page, KM_USER0);
+	header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+	cpstat->cs_cno = nilfs_mdt_cno(cpfile);
+	cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
+	cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(bh);
+
+ out_sem:
+	up_read(&NILFS_MDT(cpfile)->mi_sem);
+	return ret;
+}
diff --git a/fs/nilfs2/cpfile.h b/fs/nilfs2/cpfile.h
new file mode 100644
index 00000000000..1a8a1008c34
--- /dev/null
+++ b/fs/nilfs2/cpfile.h
@@ -0,0 +1,45 @@
+/*
+ * cpfile.h - NILFS checkpoint file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_CPFILE_H
+#define _NILFS_CPFILE_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+
+#define NILFS_CPFILE_GFP	NILFS_MDT_GFP
+
+
+int nilfs_cpfile_get_checkpoint(struct inode *, __u64, int,
+				struct nilfs_checkpoint **,
+				struct buffer_head **);
+void nilfs_cpfile_put_checkpoint(struct inode *, __u64, struct buffer_head *);
+int nilfs_cpfile_delete_checkpoints(struct inode *, __u64, __u64);
+int nilfs_cpfile_delete_checkpoint(struct inode *, __u64);
+int nilfs_cpfile_change_cpmode(struct inode *, __u64, int);
+int nilfs_cpfile_is_snapshot(struct inode *, __u64);
+int nilfs_cpfile_get_stat(struct inode *, struct nilfs_cpstat *);
+ssize_t nilfs_cpfile_get_cpinfo(struct inode *, __u64 *, int,
+				struct nilfs_cpinfo *, size_t);
+
+#endif	/* _NILFS_CPFILE_H */
diff --git a/fs/nilfs2/dat.c b/fs/nilfs2/dat.c
new file mode 100644
index 00000000000..bb8a5818e7f
--- /dev/null
+++ b/fs/nilfs2/dat.c
@@ -0,0 +1,430 @@
+/*
+ * dat.c - NILFS disk address translation.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include "nilfs.h"
+#include "mdt.h"
+#include "alloc.h"
+#include "dat.h"
+
+
+#define NILFS_CNO_MIN	((__u64)1)
+#define NILFS_CNO_MAX	(~(__u64)0)
+
+static int nilfs_dat_prepare_entry(struct inode *dat,
+				   struct nilfs_palloc_req *req, int create)
+{
+	return nilfs_palloc_get_entry_block(dat, req->pr_entry_nr,
+					    create, &req->pr_entry_bh);
+}
+
+static void nilfs_dat_commit_entry(struct inode *dat,
+				   struct nilfs_palloc_req *req)
+{
+	nilfs_mdt_mark_buffer_dirty(req->pr_entry_bh);
+	nilfs_mdt_mark_dirty(dat);
+	brelse(req->pr_entry_bh);
+}
+
+static void nilfs_dat_abort_entry(struct inode *dat,
+				  struct nilfs_palloc_req *req)
+{
+	brelse(req->pr_entry_bh);
+}
+
+int nilfs_dat_prepare_alloc(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	int ret;
+
+	ret = nilfs_palloc_prepare_alloc_entry(dat, req);
+	if (ret < 0)
+		return ret;
+
+	ret = nilfs_dat_prepare_entry(dat, req, 1);
+	if (ret < 0)
+		nilfs_palloc_abort_alloc_entry(dat, req);
+
+	return ret;
+}
+
+void nilfs_dat_commit_alloc(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	struct nilfs_dat_entry *entry;
+	void *kaddr;
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	entry->de_start = cpu_to_le64(NILFS_CNO_MIN);
+	entry->de_end = cpu_to_le64(NILFS_CNO_MAX);
+	entry->de_blocknr = cpu_to_le64(0);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_palloc_commit_alloc_entry(dat, req);
+	nilfs_dat_commit_entry(dat, req);
+}
+
+void nilfs_dat_abort_alloc(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	nilfs_dat_abort_entry(dat, req);
+	nilfs_palloc_abort_alloc_entry(dat, req);
+}
+
+int nilfs_dat_prepare_free(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	int ret;
+
+	ret = nilfs_palloc_prepare_free_entry(dat, req);
+	if (ret < 0)
+		return ret;
+	ret = nilfs_dat_prepare_entry(dat, req, 0);
+	if (ret < 0) {
+		nilfs_palloc_abort_free_entry(dat, req);
+		return ret;
+	}
+	return 0;
+}
+
+void nilfs_dat_commit_free(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	struct nilfs_dat_entry *entry;
+	void *kaddr;
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	entry->de_start = cpu_to_le64(NILFS_CNO_MIN);
+	entry->de_end = cpu_to_le64(NILFS_CNO_MIN);
+	entry->de_blocknr = cpu_to_le64(0);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_dat_commit_entry(dat, req);
+	nilfs_palloc_commit_free_entry(dat, req);
+}
+
+void nilfs_dat_abort_free(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	nilfs_dat_abort_entry(dat, req);
+	nilfs_palloc_abort_free_entry(dat, req);
+}
+
+int nilfs_dat_prepare_start(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	int ret;
+
+	ret = nilfs_dat_prepare_entry(dat, req, 0);
+	WARN_ON(ret == -ENOENT);
+	return ret;
+}
+
+void nilfs_dat_commit_start(struct inode *dat, struct nilfs_palloc_req *req,
+			    sector_t blocknr)
+{
+	struct nilfs_dat_entry *entry;
+	void *kaddr;
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	entry->de_start = cpu_to_le64(nilfs_mdt_cno(dat));
+	if (entry->de_blocknr != cpu_to_le64(0) ||
+	    entry->de_end != cpu_to_le64(NILFS_CNO_MAX)) {
+		printk(KERN_CRIT
+		       "%s: vbn = %llu, start = %llu, end = %llu, pbn = %llu\n",
+		       __func__, (unsigned long long)req->pr_entry_nr,
+		       (unsigned long long)le64_to_cpu(entry->de_start),
+		       (unsigned long long)le64_to_cpu(entry->de_end),
+		       (unsigned long long)le64_to_cpu(entry->de_blocknr));
+	}
+	entry->de_blocknr = cpu_to_le64(blocknr);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_dat_commit_entry(dat, req);
+}
+
+void nilfs_dat_abort_start(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	nilfs_dat_abort_entry(dat, req);
+}
+
+int nilfs_dat_prepare_end(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	struct nilfs_dat_entry *entry;
+	__u64 start;
+	sector_t blocknr;
+	void *kaddr;
+	int ret;
+
+	ret = nilfs_dat_prepare_entry(dat, req, 0);
+	if (ret < 0) {
+		WARN_ON(ret == -ENOENT);
+		return ret;
+	}
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	start = le64_to_cpu(entry->de_start);
+	blocknr = le64_to_cpu(entry->de_blocknr);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (blocknr == 0) {
+		ret = nilfs_palloc_prepare_free_entry(dat, req);
+		if (ret < 0) {
+			nilfs_dat_abort_entry(dat, req);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+void nilfs_dat_commit_end(struct inode *dat, struct nilfs_palloc_req *req,
+			  int dead)
+{
+	struct nilfs_dat_entry *entry;
+	__u64 start, end;
+	sector_t blocknr;
+	void *kaddr;
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	end = start = le64_to_cpu(entry->de_start);
+	if (!dead) {
+		end = nilfs_mdt_cno(dat);
+		WARN_ON(start > end);
+	}
+	entry->de_end = cpu_to_le64(end);
+	blocknr = le64_to_cpu(entry->de_blocknr);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (blocknr == 0)
+		nilfs_dat_commit_free(dat, req);
+	else
+		nilfs_dat_commit_entry(dat, req);
+}
+
+void nilfs_dat_abort_end(struct inode *dat, struct nilfs_palloc_req *req)
+{
+	struct nilfs_dat_entry *entry;
+	__u64 start;
+	sector_t blocknr;
+	void *kaddr;
+
+	kaddr = kmap_atomic(req->pr_entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
+					     req->pr_entry_bh, kaddr);
+	start = le64_to_cpu(entry->de_start);
+	blocknr = le64_to_cpu(entry->de_blocknr);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (start == nilfs_mdt_cno(dat) && blocknr == 0)
+		nilfs_palloc_abort_free_entry(dat, req);
+	nilfs_dat_abort_entry(dat, req);
+}
+
+/**
+ * nilfs_dat_mark_dirty -
+ * @dat: DAT file inode
+ * @vblocknr: virtual block number
+ *
+ * Description:
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_dat_mark_dirty(struct inode *dat, __u64 vblocknr)
+{
+	struct nilfs_palloc_req req;
+	int ret;
+
+	req.pr_entry_nr = vblocknr;
+	ret = nilfs_dat_prepare_entry(dat, &req, 0);
+	if (ret == 0)
+		nilfs_dat_commit_entry(dat, &req);
+	return ret;
+}
+
+/**
+ * nilfs_dat_freev - free virtual block numbers
+ * @dat: DAT file inode
+ * @vblocknrs: array of virtual block numbers
+ * @nitems: number of virtual block numbers
+ *
+ * Description: nilfs_dat_freev() frees the virtual block numbers specified by
+ * @vblocknrs and @nitems.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * nagative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - The virtual block number have not been allocated.
+ */
+int nilfs_dat_freev(struct inode *dat, __u64 *vblocknrs, size_t nitems)
+{
+	return nilfs_palloc_freev(dat, vblocknrs, nitems);
+}
+
+/**
+ * nilfs_dat_move - change a block number
+ * @dat: DAT file inode
+ * @vblocknr: virtual block number
+ * @blocknr: block number
+ *
+ * Description: nilfs_dat_move() changes the block number associated with
+ * @vblocknr to @blocknr.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_dat_move(struct inode *dat, __u64 vblocknr, sector_t blocknr)
+{
+	struct buffer_head *entry_bh;
+	struct nilfs_dat_entry *entry;
+	void *kaddr;
+	int ret;
+
+	ret = nilfs_palloc_get_entry_block(dat, vblocknr, 0, &entry_bh);
+	if (ret < 0)
+		return ret;
+	kaddr = kmap_atomic(entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, vblocknr, entry_bh, kaddr);
+	if (unlikely(entry->de_blocknr == cpu_to_le64(0))) {
+		printk(KERN_CRIT "%s: vbn = %llu, [%llu, %llu)\n", __func__,
+		       (unsigned long long)vblocknr,
+		       (unsigned long long)le64_to_cpu(entry->de_start),
+		       (unsigned long long)le64_to_cpu(entry->de_end));
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(entry_bh);
+		return -EINVAL;
+	}
+	WARN_ON(blocknr == 0);
+	entry->de_blocknr = cpu_to_le64(blocknr);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_mdt_mark_buffer_dirty(entry_bh);
+	nilfs_mdt_mark_dirty(dat);
+
+	brelse(entry_bh);
+
+	return 0;
+}
+
+/**
+ * nilfs_dat_translate - translate a virtual block number to a block number
+ * @dat: DAT file inode
+ * @vblocknr: virtual block number
+ * @blocknrp: pointer to a block number
+ *
+ * Description: nilfs_dat_translate() maps the virtual block number @vblocknr
+ * to the corresponding block number.
+ *
+ * Return Value: On success, 0 is returned and the block number associated
+ * with @vblocknr is stored in the place pointed by @blocknrp. On error, one
+ * of the following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - A block number associated with @vblocknr does not exist.
+ */
+int nilfs_dat_translate(struct inode *dat, __u64 vblocknr, sector_t *blocknrp)
+{
+	struct buffer_head *entry_bh;
+	struct nilfs_dat_entry *entry;
+	sector_t blocknr;
+	void *kaddr;
+	int ret;
+
+	ret = nilfs_palloc_get_entry_block(dat, vblocknr, 0, &entry_bh);
+	if (ret < 0)
+		return ret;
+
+	kaddr = kmap_atomic(entry_bh->b_page, KM_USER0);
+	entry = nilfs_palloc_block_get_entry(dat, vblocknr, entry_bh, kaddr);
+	blocknr = le64_to_cpu(entry->de_blocknr);
+	if (blocknr == 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+	if (blocknrp != NULL)
+		*blocknrp = blocknr;
+
+ out:
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(entry_bh);
+	return ret;
+}
+
+ssize_t nilfs_dat_get_vinfo(struct inode *dat, struct nilfs_vinfo *vinfo,
+			    size_t nvi)
+{
+	struct buffer_head *entry_bh;
+	struct nilfs_dat_entry *entry;
+	__u64 first, last;
+	void *kaddr;
+	unsigned long entries_per_block = NILFS_MDT(dat)->mi_entries_per_block;
+	int i, j, n, ret;
+
+	for (i = 0; i < nvi; i += n) {
+		ret = nilfs_palloc_get_entry_block(dat, vinfo[i].vi_vblocknr,
+						   0, &entry_bh);
+		if (ret < 0)
+			return ret;
+		kaddr = kmap_atomic(entry_bh->b_page, KM_USER0);
+		/* last virtual block number in this block */
+		first = vinfo[i].vi_vblocknr;
+		do_div(first, entries_per_block);
+		first *= entries_per_block;
+		last = first + entries_per_block - 1;
+		for (j = i, n = 0;
+		     j < nvi && vinfo[j].vi_vblocknr >= first &&
+			     vinfo[j].vi_vblocknr <= last;
+		     j++, n++) {
+			entry = nilfs_palloc_block_get_entry(
+				dat, vinfo[j].vi_vblocknr, entry_bh, kaddr);
+			vinfo[j].vi_start = le64_to_cpu(entry->de_start);
+			vinfo[j].vi_end = le64_to_cpu(entry->de_end);
+			vinfo[j].vi_blocknr = le64_to_cpu(entry->de_blocknr);
+		}
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(entry_bh);
+	}
+
+	return nvi;
+}
diff --git a/fs/nilfs2/dat.h b/fs/nilfs2/dat.h
new file mode 100644
index 00000000000..d9560654a4b
--- /dev/null
+++ b/fs/nilfs2/dat.h
@@ -0,0 +1,52 @@
+/*
+ * dat.h - NILFS disk address translation.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_DAT_H
+#define _NILFS_DAT_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+
+#define NILFS_DAT_GFP	NILFS_MDT_GFP
+
+struct nilfs_palloc_req;
+
+int nilfs_dat_translate(struct inode *, __u64, sector_t *);
+
+int nilfs_dat_prepare_alloc(struct inode *, struct nilfs_palloc_req *);
+void nilfs_dat_commit_alloc(struct inode *, struct nilfs_palloc_req *);
+void nilfs_dat_abort_alloc(struct inode *, struct nilfs_palloc_req *);
+int nilfs_dat_prepare_start(struct inode *, struct nilfs_palloc_req *);
+void nilfs_dat_commit_start(struct inode *, struct nilfs_palloc_req *,
+			    sector_t);
+void nilfs_dat_abort_start(struct inode *, struct nilfs_palloc_req *);
+int nilfs_dat_prepare_end(struct inode *, struct nilfs_palloc_req *);
+void nilfs_dat_commit_end(struct inode *, struct nilfs_palloc_req *, int);
+void nilfs_dat_abort_end(struct inode *, struct nilfs_palloc_req *);
+
+int nilfs_dat_mark_dirty(struct inode *, __u64);
+int nilfs_dat_freev(struct inode *, __u64 *, size_t);
+int nilfs_dat_move(struct inode *, __u64, sector_t);
+ssize_t nilfs_dat_get_vinfo(struct inode *, struct nilfs_vinfo *, size_t);
+
+#endif	/* _NILFS_DAT_H */
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
new file mode 100644
index 00000000000..54100acc110
--- /dev/null
+++ b/fs/nilfs2/dir.c
@@ -0,0 +1,711 @@
+/*
+ * dir.c - NILFS directory entry operations
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
+ */
+/*
+ *  linux/fs/ext2/dir.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/dir.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  ext2 directory handling functions
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ *
+ * All code that works with directory layout had been switched to pagecache
+ * and moved here. AV
+ */
+
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+#include "nilfs.h"
+#include "page.h"
+
+/*
+ * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
+ * more robust, but we have what we have
+ */
+static inline unsigned nilfs_chunk_size(struct inode *inode)
+{
+	return inode->i_sb->s_blocksize;
+}
+
+static inline void nilfs_put_page(struct page *page)
+{
+	kunmap(page);
+	page_cache_release(page);
+}
+
+static inline unsigned long dir_pages(struct inode *inode)
+{
+	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+}
+
+/*
+ * Return the offset into page `page_nr' of the last valid
+ * byte in that page, plus one.
+ */
+static unsigned nilfs_last_byte(struct inode *inode, unsigned long page_nr)
+{
+	unsigned last_byte = inode->i_size;
+
+	last_byte -= page_nr << PAGE_CACHE_SHIFT;
+	if (last_byte > PAGE_CACHE_SIZE)
+		last_byte = PAGE_CACHE_SIZE;
+	return last_byte;
+}
+
+static int nilfs_prepare_chunk_uninterruptible(struct page *page,
+					       struct address_space *mapping,
+					       unsigned from, unsigned to)
+{
+	loff_t pos = page_offset(page) + from;
+	return block_write_begin(NULL, mapping, pos, to - from,
+				 AOP_FLAG_UNINTERRUPTIBLE, &page,
+				 NULL, nilfs_get_block);
+}
+
+static int nilfs_prepare_chunk(struct page *page,
+			       struct address_space *mapping,
+			       unsigned from, unsigned to)
+{
+	loff_t pos = page_offset(page) + from;
+	return block_write_begin(NULL, mapping, pos, to - from, 0, &page,
+				 NULL, nilfs_get_block);
+}
+
+static int nilfs_commit_chunk(struct page *page,
+			      struct address_space *mapping,
+			      unsigned from, unsigned to)
+{
+	struct inode *dir = mapping->host;
+	struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
+	loff_t pos = page_offset(page) + from;
+	unsigned len = to - from;
+	unsigned nr_dirty, copied;
+	int err;
+
+	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
+	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
+	if (pos + copied > dir->i_size) {
+		i_size_write(dir, pos + copied);
+		mark_inode_dirty(dir);
+	}
+	if (IS_DIRSYNC(dir))
+		nilfs_set_transaction_flag(NILFS_TI_SYNC);
+	err = nilfs_set_file_dirty(sbi, dir, nr_dirty);
+	unlock_page(page);
+	return err;
+}
+
+static void nilfs_check_page(struct page *page)
+{
+	struct inode *dir = page->mapping->host;
+	struct super_block *sb = dir->i_sb;
+	unsigned chunk_size = nilfs_chunk_size(dir);
+	char *kaddr = page_address(page);
+	unsigned offs, rec_len;
+	unsigned limit = PAGE_CACHE_SIZE;
+	struct nilfs_dir_entry *p;
+	char *error;
+
+	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
+		limit = dir->i_size & ~PAGE_CACHE_MASK;
+		if (limit & (chunk_size - 1))
+			goto Ebadsize;
+		if (!limit)
+			goto out;
+	}
+	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
+		p = (struct nilfs_dir_entry *)(kaddr + offs);
+		rec_len = le16_to_cpu(p->rec_len);
+
+		if (rec_len < NILFS_DIR_REC_LEN(1))
+			goto Eshort;
+		if (rec_len & 3)
+			goto Ealign;
+		if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
+			goto Enamelen;
+		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
+			goto Espan;
+	}
+	if (offs != limit)
+		goto Eend;
+out:
+	SetPageChecked(page);
+	return;
+
+	/* Too bad, we had an error */
+
+Ebadsize:
+	nilfs_error(sb, "nilfs_check_page",
+		    "size of directory #%lu is not a multiple of chunk size",
+		    dir->i_ino
+	);
+	goto fail;
+Eshort:
+	error = "rec_len is smaller than minimal";
+	goto bad_entry;
+Ealign:
+	error = "unaligned directory entry";
+	goto bad_entry;
+Enamelen:
+	error = "rec_len is too small for name_len";
+	goto bad_entry;
+Espan:
+	error = "directory entry across blocks";
+bad_entry:
+	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
+		    "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
+		    dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
+		    (unsigned long) le64_to_cpu(p->inode),
+		    rec_len, p->name_len);
+	goto fail;
+Eend:
+	p = (struct nilfs_dir_entry *)(kaddr + offs);
+	nilfs_error(sb, "nilfs_check_page",
+		    "entry in directory #%lu spans the page boundary"
+		    "offset=%lu, inode=%lu",
+		    dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
+		    (unsigned long) le64_to_cpu(p->inode));
+fail:
+	SetPageChecked(page);
+	SetPageError(page);
+}
+
+static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
+{
+	struct address_space *mapping = dir->i_mapping;
+	struct page *page = read_cache_page(mapping, n,
+				(filler_t *)mapping->a_ops->readpage, NULL);
+	if (!IS_ERR(page)) {
+		wait_on_page_locked(page);
+		kmap(page);
+		if (!PageUptodate(page))
+			goto fail;
+		if (!PageChecked(page))
+			nilfs_check_page(page);
+		if (PageError(page))
+			goto fail;
+	}
+	return page;
+
+fail:
+	nilfs_put_page(page);
+	return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
+ *
+ * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static int
+nilfs_match(int len, const char * const name, struct nilfs_dir_entry *de)
+{
+	if (len != de->name_len)
+		return 0;
+	if (!de->inode)
+		return 0;
+	return !memcmp(name, de->name, len);
+}
+
+/*
+ * p is at least 6 bytes before the end of page
+ */
+static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
+{
+	return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
+}
+
+static unsigned char
+nilfs_filetype_table[NILFS_FT_MAX] = {
+	[NILFS_FT_UNKNOWN]	= DT_UNKNOWN,
+	[NILFS_FT_REG_FILE]	= DT_REG,
+	[NILFS_FT_DIR]		= DT_DIR,
+	[NILFS_FT_CHRDEV]	= DT_CHR,
+	[NILFS_FT_BLKDEV]	= DT_BLK,
+	[NILFS_FT_FIFO]		= DT_FIFO,
+	[NILFS_FT_SOCK]		= DT_SOCK,
+	[NILFS_FT_SYMLINK]	= DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char
+nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
+	[S_IFREG >> S_SHIFT]	= NILFS_FT_REG_FILE,
+	[S_IFDIR >> S_SHIFT]	= NILFS_FT_DIR,
+	[S_IFCHR >> S_SHIFT]	= NILFS_FT_CHRDEV,
+	[S_IFBLK >> S_SHIFT]	= NILFS_FT_BLKDEV,
+	[S_IFIFO >> S_SHIFT]	= NILFS_FT_FIFO,
+	[S_IFSOCK >> S_SHIFT]	= NILFS_FT_SOCK,
+	[S_IFLNK >> S_SHIFT]	= NILFS_FT_SYMLINK,
+};
+
+static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
+{
+	mode_t mode = inode->i_mode;
+
+	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
+}
+
+static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	loff_t pos = filp->f_pos;
+	struct inode *inode = filp->f_dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
+	unsigned int offset = pos & ~PAGE_CACHE_MASK;
+	unsigned long n = pos >> PAGE_CACHE_SHIFT;
+	unsigned long npages = dir_pages(inode);
+/*	unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
+	unsigned char *types = NULL;
+	int ret;
+
+	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
+		goto success;
+
+	types = nilfs_filetype_table;
+
+	for ( ; n < npages; n++, offset = 0) {
+		char *kaddr, *limit;
+		struct nilfs_dir_entry *de;
+		struct page *page = nilfs_get_page(inode, n);
+
+		if (IS_ERR(page)) {
+			nilfs_error(sb, __func__, "bad page in #%lu",
+				    inode->i_ino);
+			filp->f_pos += PAGE_CACHE_SIZE - offset;
+			ret = -EIO;
+			goto done;
+		}
+		kaddr = page_address(page);
+		de = (struct nilfs_dir_entry *)(kaddr + offset);
+		limit = kaddr + nilfs_last_byte(inode, n) -
+			NILFS_DIR_REC_LEN(1);
+		for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
+			if (de->rec_len == 0) {
+				nilfs_error(sb, __func__,
+					    "zero-length directory entry");
+				ret = -EIO;
+				nilfs_put_page(page);
+				goto done;
+			}
+			if (de->inode) {
+				int over;
+				unsigned char d_type = DT_UNKNOWN;
+
+				if (types && de->file_type < NILFS_FT_MAX)
+					d_type = types[de->file_type];
+
+				offset = (char *)de - kaddr;
+				over = filldir(dirent, de->name, de->name_len,
+						(n<<PAGE_CACHE_SHIFT) | offset,
+						le64_to_cpu(de->inode), d_type);
+				if (over) {
+					nilfs_put_page(page);
+					goto success;
+				}
+			}
+			filp->f_pos += le16_to_cpu(de->rec_len);
+		}
+		nilfs_put_page(page);
+	}
+
+success:
+	ret = 0;
+done:
+	return ret;
+}
+
+/*
+ *	nilfs_find_entry()
+ *
+ * finds an entry in the specified directory with the wanted name. It
+ * returns the page in which the entry was found, and the entry itself
+ * (as a parameter - res_dir). Page is returned mapped and unlocked.
+ * Entry is guaranteed to be valid.
+ */
+struct nilfs_dir_entry *
+nilfs_find_entry(struct inode *dir, struct dentry *dentry,
+		 struct page **res_page)
+{
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
+	unsigned long start, n;
+	unsigned long npages = dir_pages(dir);
+	struct page *page = NULL;
+	struct nilfs_inode_info *ei = NILFS_I(dir);
+	struct nilfs_dir_entry *de;
+
+	if (npages == 0)
+		goto out;
+
+	/* OFFSET_CACHE */
+	*res_page = NULL;
+
+	start = ei->i_dir_start_lookup;
+	if (start >= npages)
+		start = 0;
+	n = start;
+	do {
+		char *kaddr;
+		page = nilfs_get_page(dir, n);
+		if (!IS_ERR(page)) {
+			kaddr = page_address(page);
+			de = (struct nilfs_dir_entry *)kaddr;
+			kaddr += nilfs_last_byte(dir, n) - reclen;
+			while ((char *) de <= kaddr) {
+				if (de->rec_len == 0) {
+					nilfs_error(dir->i_sb, __func__,
+						"zero-length directory entry");
+					nilfs_put_page(page);
+					goto out;
+				}
+				if (nilfs_match(namelen, name, de))
+					goto found;
+				de = nilfs_next_entry(de);
+			}
+			nilfs_put_page(page);
+		}
+		if (++n >= npages)
+			n = 0;
+		/* next page is past the blocks we've got */
+		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
+			nilfs_error(dir->i_sb, __func__,
+			       "dir %lu size %lld exceeds block cout %llu",
+			       dir->i_ino, dir->i_size,
+			       (unsigned long long)dir->i_blocks);
+			goto out;
+		}
+	} while (n != start);
+out:
+	return NULL;
+
+found:
+	*res_page = page;
+	ei->i_dir_start_lookup = n;
+	return de;
+}
+
+struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
+{
+	struct page *page = nilfs_get_page(dir, 0);
+	struct nilfs_dir_entry *de = NULL;
+
+	if (!IS_ERR(page)) {
+		de = nilfs_next_entry(
+			(struct nilfs_dir_entry *)page_address(page));
+		*p = page;
+	}
+	return de;
+}
+
+ino_t nilfs_inode_by_name(struct inode *dir, struct dentry *dentry)
+{
+	ino_t res = 0;
+	struct nilfs_dir_entry *de;
+	struct page *page;
+
+	de = nilfs_find_entry(dir, dentry, &page);
+	if (de) {
+		res = le64_to_cpu(de->inode);
+		kunmap(page);
+		page_cache_release(page);
+	}
+	return res;
+}
+
+/* Releases the page */
+void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
+		    struct page *page, struct inode *inode)
+{
+	unsigned from = (char *) de - (char *) page_address(page);
+	unsigned to = from + le16_to_cpu(de->rec_len);
+	struct address_space *mapping = page->mapping;
+	int err;
+
+	lock_page(page);
+	err = nilfs_prepare_chunk_uninterruptible(page, mapping, from, to);
+	BUG_ON(err);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+	err = nilfs_commit_chunk(page, mapping, from, to);
+	nilfs_put_page(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*	NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(dir);
+}
+
+/*
+ *	Parent is locked.
+ */
+int nilfs_add_link(struct dentry *dentry, struct inode *inode)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned chunk_size = nilfs_chunk_size(dir);
+	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
+	unsigned short rec_len, name_len;
+	struct page *page = NULL;
+	struct nilfs_dir_entry *de;
+	unsigned long npages = dir_pages(dir);
+	unsigned long n;
+	char *kaddr;
+	unsigned from, to;
+	int err;
+
+	/*
+	 * We take care of directory expansion in the same loop.
+	 * This code plays outside i_size, so it locks the page
+	 * to protect that region.
+	 */
+	for (n = 0; n <= npages; n++) {
+		char *dir_end;
+
+		page = nilfs_get_page(dir, n);
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto out;
+		lock_page(page);
+		kaddr = page_address(page);
+		dir_end = kaddr + nilfs_last_byte(dir, n);
+		de = (struct nilfs_dir_entry *)kaddr;
+		kaddr += PAGE_CACHE_SIZE - reclen;
+		while ((char *)de <= kaddr) {
+			if ((char *)de == dir_end) {
+				/* We hit i_size */
+				name_len = 0;
+				rec_len = chunk_size;
+				de->rec_len = cpu_to_le16(chunk_size);
+				de->inode = 0;
+				goto got_it;
+			}
+			if (de->rec_len == 0) {
+				nilfs_error(dir->i_sb, __func__,
+					    "zero-length directory entry");
+				err = -EIO;
+				goto out_unlock;
+			}
+			err = -EEXIST;
+			if (nilfs_match(namelen, name, de))
+				goto out_unlock;
+			name_len = NILFS_DIR_REC_LEN(de->name_len);
+			rec_len = le16_to_cpu(de->rec_len);
+			if (!de->inode && rec_len >= reclen)
+				goto got_it;
+			if (rec_len >= name_len + reclen)
+				goto got_it;
+			de = (struct nilfs_dir_entry *)((char *)de + rec_len);
+		}
+		unlock_page(page);
+		nilfs_put_page(page);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	from = (char *)de - (char *)page_address(page);
+	to = from + rec_len;
+	err = nilfs_prepare_chunk(page, page->mapping, from, to);
+	if (err)
+		goto out_unlock;
+	if (de->inode) {
+		struct nilfs_dir_entry *de1;
+
+		de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
+		de1->rec_len = cpu_to_le16(rec_len - name_len);
+		de->rec_len = cpu_to_le16(name_len);
+		de = de1;
+	}
+	de->name_len = namelen;
+	memcpy(de->name, name, namelen);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+	err = nilfs_commit_chunk(page, page->mapping, from, to);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*	NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(dir);
+	/* OFFSET_CACHE */
+out_put:
+	nilfs_put_page(page);
+out:
+	return err;
+out_unlock:
+	unlock_page(page);
+	goto out_put;
+}
+
+/*
+ * nilfs_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date. Releases the page.
+ */
+int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	char *kaddr = page_address(page);
+	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
+	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
+	struct nilfs_dir_entry *pde = NULL;
+	struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
+	int err;
+
+	while ((char *)de < (char *)dir) {
+		if (de->rec_len == 0) {
+			nilfs_error(inode->i_sb, __func__,
+				    "zero-length directory entry");
+			err = -EIO;
+			goto out;
+		}
+		pde = de;
+		de = nilfs_next_entry(de);
+	}
+	if (pde)
+		from = (char *)pde - (char *)page_address(page);
+	lock_page(page);
+	err = nilfs_prepare_chunk(page, mapping, from, to);
+	BUG_ON(err);
+	if (pde)
+		pde->rec_len = cpu_to_le16(to - from);
+	dir->inode = 0;
+	err = nilfs_commit_chunk(page, mapping, from, to);
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+/*	NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(inode);
+out:
+	nilfs_put_page(page);
+	return err;
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int nilfs_make_empty(struct inode *inode, struct inode *parent)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page = grab_cache_page(mapping, 0);
+	unsigned chunk_size = nilfs_chunk_size(inode);
+	struct nilfs_dir_entry *de;
+	int err;
+	void *kaddr;
+
+	if (!page)
+		return -ENOMEM;
+
+	err = nilfs_prepare_chunk(page, mapping, 0, chunk_size);
+	if (unlikely(err)) {
+		unlock_page(page);
+		goto fail;
+	}
+	kaddr = kmap_atomic(page, KM_USER0);
+	memset(kaddr, 0, chunk_size);
+	de = (struct nilfs_dir_entry *)kaddr;
+	de->name_len = 1;
+	de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));
+	memcpy(de->name, ".\0\0", 4);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+
+	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
+	de->name_len = 2;
+	de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));
+	de->inode = cpu_to_le64(parent->i_ino);
+	memcpy(de->name, "..\0", 4);
+	nilfs_set_de_type(de, inode);
+	kunmap_atomic(kaddr, KM_USER0);
+	err = nilfs_commit_chunk(page, mapping, 0, chunk_size);
+fail:
+	page_cache_release(page);
+	return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int nilfs_empty_dir(struct inode *inode)
+{
+	struct page *page = NULL;
+	unsigned long i, npages = dir_pages(inode);
+
+	for (i = 0; i < npages; i++) {
+		char *kaddr;
+		struct nilfs_dir_entry *de;
+
+		page = nilfs_get_page(inode, i);
+		if (IS_ERR(page))
+			continue;
+
+		kaddr = page_address(page);
+		de = (struct nilfs_dir_entry *)kaddr;
+		kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
+
+		while ((char *)de <= kaddr) {
+			if (de->rec_len == 0) {
+				nilfs_error(inode->i_sb, __func__,
+					    "zero-length directory entry "
+					    "(kaddr=%p, de=%p)\n", kaddr, de);
+				goto not_empty;
+			}
+			if (de->inode != 0) {
+				/* check for . and .. */
+				if (de->name[0] != '.')
+					goto not_empty;
+				if (de->name_len > 2)
+					goto not_empty;
+				if (de->name_len < 2) {
+					if (de->inode !=
+					    cpu_to_le64(inode->i_ino))
+						goto not_empty;
+				} else if (de->name[1] != '.')
+					goto not_empty;
+			}
+			de = nilfs_next_entry(de);
+		}
+		nilfs_put_page(page);
+	}
+	return 1;
+
+not_empty:
+	nilfs_put_page(page);
+	return 0;
+}
+
+struct file_operations nilfs_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.readdir	= nilfs_readdir,
+	.unlocked_ioctl	= nilfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= nilfs_ioctl,
+#endif	/* CONFIG_COMPAT */
+	.fsync		= nilfs_sync_file,
+
+};
diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
new file mode 100644
index 00000000000..c6379e48278
--- /dev/null
+++ b/fs/nilfs2/direct.c
@@ -0,0 +1,436 @@
+/*
+ * direct.c - NILFS direct block pointer.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/errno.h>
+#include "nilfs.h"
+#include "page.h"
+#include "direct.h"
+#include "alloc.h"
+
+static inline __le64 *nilfs_direct_dptrs(const struct nilfs_direct *direct)
+{
+	return (__le64 *)
+		((struct nilfs_direct_node *)direct->d_bmap.b_u.u_data + 1);
+}
+
+static inline __u64
+nilfs_direct_get_ptr(const struct nilfs_direct *direct, __u64 key)
+{
+	return nilfs_bmap_dptr_to_ptr(*(nilfs_direct_dptrs(direct) + key));
+}
+
+static inline void nilfs_direct_set_ptr(struct nilfs_direct *direct,
+					__u64 key, __u64 ptr)
+{
+	*(nilfs_direct_dptrs(direct) + key) = nilfs_bmap_ptr_to_dptr(ptr);
+}
+
+static int nilfs_direct_lookup(const struct nilfs_bmap *bmap,
+			       __u64 key, int level, __u64 *ptrp)
+{
+	struct nilfs_direct *direct;
+	__u64 ptr;
+
+	direct = (struct nilfs_direct *)bmap;
+	if ((key > NILFS_DIRECT_KEY_MAX) ||
+	    (level != 1) ||	/* XXX: use macro for level 1 */
+	    ((ptr = nilfs_direct_get_ptr(direct, key)) ==
+	     NILFS_BMAP_INVALID_PTR))
+		return -ENOENT;
+
+	if (ptrp != NULL)
+		*ptrp = ptr;
+	return 0;
+}
+
+static __u64
+nilfs_direct_find_target_v(const struct nilfs_direct *direct, __u64 key)
+{
+	__u64 ptr;
+
+	ptr = nilfs_bmap_find_target_seq(&direct->d_bmap, key);
+	if (ptr != NILFS_BMAP_INVALID_PTR)
+		/* sequential access */
+		return ptr;
+	else
+		/* block group */
+		return nilfs_bmap_find_target_in_group(&direct->d_bmap);
+}
+
+static void nilfs_direct_set_target_v(struct nilfs_direct *direct,
+				      __u64 key, __u64 ptr)
+{
+	direct->d_bmap.b_last_allocated_key = key;
+	direct->d_bmap.b_last_allocated_ptr = ptr;
+}
+
+static int nilfs_direct_prepare_insert(struct nilfs_direct *direct,
+				       __u64 key,
+				       union nilfs_bmap_ptr_req *req,
+				       struct nilfs_bmap_stats *stats)
+{
+	int ret;
+
+	if (direct->d_ops->dop_find_target != NULL)
+		req->bpr_ptr = direct->d_ops->dop_find_target(direct, key);
+	ret = direct->d_bmap.b_pops->bpop_prepare_alloc_ptr(&direct->d_bmap,
+							       req);
+	if (ret < 0)
+		return ret;
+
+	stats->bs_nblocks = 1;
+	return 0;
+}
+
+static void nilfs_direct_commit_insert(struct nilfs_direct *direct,
+				       union nilfs_bmap_ptr_req *req,
+				       __u64 key, __u64 ptr)
+{
+	struct buffer_head *bh;
+
+	/* ptr must be a pointer to a buffer head. */
+	bh = (struct buffer_head *)((unsigned long)ptr);
+	set_buffer_nilfs_volatile(bh);
+
+	if (direct->d_bmap.b_pops->bpop_commit_alloc_ptr != NULL)
+		direct->d_bmap.b_pops->bpop_commit_alloc_ptr(
+			&direct->d_bmap, req);
+	nilfs_direct_set_ptr(direct, key, req->bpr_ptr);
+
+	if (!nilfs_bmap_dirty(&direct->d_bmap))
+		nilfs_bmap_set_dirty(&direct->d_bmap);
+
+	if (direct->d_ops->dop_set_target != NULL)
+		direct->d_ops->dop_set_target(direct, key, req->bpr_ptr);
+}
+
+static int nilfs_direct_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
+{
+	struct nilfs_direct *direct;
+	union nilfs_bmap_ptr_req req;
+	struct nilfs_bmap_stats stats;
+	int ret;
+
+	direct = (struct nilfs_direct *)bmap;
+	if (key > NILFS_DIRECT_KEY_MAX)
+		return -ENOENT;
+	if (nilfs_direct_get_ptr(direct, key) != NILFS_BMAP_INVALID_PTR)
+		return -EEXIST;
+
+	ret = nilfs_direct_prepare_insert(direct, key, &req, &stats);
+	if (ret < 0)
+		return ret;
+	nilfs_direct_commit_insert(direct, &req, key, ptr);
+	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
+
+	return 0;
+}
+
+static int nilfs_direct_prepare_delete(struct nilfs_direct *direct,
+				       union nilfs_bmap_ptr_req *req,
+				       __u64 key,
+				       struct nilfs_bmap_stats *stats)
+{
+	int ret;
+
+	if (direct->d_bmap.b_pops->bpop_prepare_end_ptr != NULL) {
+		req->bpr_ptr = nilfs_direct_get_ptr(direct, key);
+		ret = direct->d_bmap.b_pops->bpop_prepare_end_ptr(
+			&direct->d_bmap, req);
+		if (ret < 0)
+			return ret;
+	}
+
+	stats->bs_nblocks = 1;
+	return 0;
+}
+
+static void nilfs_direct_commit_delete(struct nilfs_direct *direct,
+				       union nilfs_bmap_ptr_req *req,
+				       __u64 key)
+{
+	if (direct->d_bmap.b_pops->bpop_commit_end_ptr != NULL)
+		direct->d_bmap.b_pops->bpop_commit_end_ptr(
+			&direct->d_bmap, req);
+	nilfs_direct_set_ptr(direct, key, NILFS_BMAP_INVALID_PTR);
+}
+
+static int nilfs_direct_delete(struct nilfs_bmap *bmap, __u64 key)
+{
+	struct nilfs_direct *direct;
+	union nilfs_bmap_ptr_req req;
+	struct nilfs_bmap_stats stats;
+	int ret;
+
+	direct = (struct nilfs_direct *)bmap;
+	if ((key > NILFS_DIRECT_KEY_MAX) ||
+	    nilfs_direct_get_ptr(direct, key) == NILFS_BMAP_INVALID_PTR)
+		return -ENOENT;
+
+	ret = nilfs_direct_prepare_delete(direct, &req, key, &stats);
+	if (ret < 0)
+		return ret;
+	nilfs_direct_commit_delete(direct, &req, key);
+	nilfs_bmap_sub_blocks(bmap, stats.bs_nblocks);
+
+	return 0;
+}
+
+static int nilfs_direct_last_key(const struct nilfs_bmap *bmap, __u64 *keyp)
+{
+	struct nilfs_direct *direct;
+	__u64 key, lastkey;
+
+	direct = (struct nilfs_direct *)bmap;
+	lastkey = NILFS_DIRECT_KEY_MAX + 1;
+	for (key = NILFS_DIRECT_KEY_MIN; key <= NILFS_DIRECT_KEY_MAX; key++)
+		if (nilfs_direct_get_ptr(direct, key) !=
+		    NILFS_BMAP_INVALID_PTR)
+			lastkey = key;
+
+	if (lastkey == NILFS_DIRECT_KEY_MAX + 1)
+		return -ENOENT;
+
+	*keyp = lastkey;
+
+	return 0;
+}
+
+static int nilfs_direct_check_insert(const struct nilfs_bmap *bmap, __u64 key)
+{
+	return key > NILFS_DIRECT_KEY_MAX;
+}
+
+static int nilfs_direct_gather_data(struct nilfs_bmap *bmap,
+				    __u64 *keys, __u64 *ptrs, int nitems)
+{
+	struct nilfs_direct *direct;
+	__u64 key;
+	__u64 ptr;
+	int n;
+
+	direct = (struct nilfs_direct *)bmap;
+	if (nitems > NILFS_DIRECT_NBLOCKS)
+		nitems = NILFS_DIRECT_NBLOCKS;
+	n = 0;
+	for (key = 0; key < nitems; key++) {
+		ptr = nilfs_direct_get_ptr(direct, key);
+		if (ptr != NILFS_BMAP_INVALID_PTR) {
+			keys[n] = key;
+			ptrs[n] = ptr;
+			n++;
+		}
+	}
+	return n;
+}
+
+int nilfs_direct_delete_and_convert(struct nilfs_bmap *bmap,
+				    __u64 key, __u64 *keys, __u64 *ptrs,
+				    int n, __u64 low, __u64 high)
+{
+	struct nilfs_direct *direct;
+	__le64 *dptrs;
+	int ret, i, j;
+
+	/* no need to allocate any resource for conversion */
+
+	/* delete */
+	ret = bmap->b_ops->bop_delete(bmap, key);
+	if (ret < 0)
+		return ret;
+
+	/* free resources */
+	if (bmap->b_ops->bop_clear != NULL)
+		bmap->b_ops->bop_clear(bmap);
+
+	/* convert */
+	direct = (struct nilfs_direct *)bmap;
+	dptrs = nilfs_direct_dptrs(direct);
+	for (i = 0, j = 0; i < NILFS_DIRECT_NBLOCKS; i++) {
+		if ((j < n) && (i == keys[j])) {
+			dptrs[i] = (i != key) ?
+				nilfs_bmap_ptr_to_dptr(ptrs[j]) :
+				NILFS_BMAP_INVALID_PTR;
+			j++;
+		} else
+			dptrs[i] = NILFS_BMAP_INVALID_PTR;
+	}
+
+	nilfs_direct_init(bmap, low, high);
+
+	return 0;
+}
+
+static int nilfs_direct_propagate_v(struct nilfs_direct *direct,
+				    struct buffer_head *bh)
+{
+	union nilfs_bmap_ptr_req oldreq, newreq;
+	__u64 key;
+	__u64 ptr;
+	int ret;
+
+	key = nilfs_bmap_data_get_key(&direct->d_bmap, bh);
+	ptr = nilfs_direct_get_ptr(direct, key);
+	if (!buffer_nilfs_volatile(bh)) {
+		oldreq.bpr_ptr = ptr;
+		newreq.bpr_ptr = ptr;
+		ret = nilfs_bmap_prepare_update(&direct->d_bmap, &oldreq,
+						&newreq);
+		if (ret < 0)
+			return ret;
+		nilfs_bmap_commit_update(&direct->d_bmap, &oldreq, &newreq);
+		set_buffer_nilfs_volatile(bh);
+		nilfs_direct_set_ptr(direct, key, newreq.bpr_ptr);
+	} else
+		ret = nilfs_bmap_mark_dirty(&direct->d_bmap, ptr);
+
+	return ret;
+}
+
+static int nilfs_direct_propagate(const struct nilfs_bmap *bmap,
+				  struct buffer_head *bh)
+{
+	struct nilfs_direct *direct;
+
+	direct = (struct nilfs_direct *)bmap;
+	return (direct->d_ops->dop_propagate != NULL) ?
+		direct->d_ops->dop_propagate(direct, bh) :
+		0;
+}
+
+static int nilfs_direct_assign_v(struct nilfs_direct *direct,
+				 __u64 key, __u64 ptr,
+				 struct buffer_head **bh,
+				 sector_t blocknr,
+				 union nilfs_binfo *binfo)
+{
+	union nilfs_bmap_ptr_req req;
+	int ret;
+
+	req.bpr_ptr = ptr;
+	ret = direct->d_bmap.b_pops->bpop_prepare_start_ptr(
+		&direct->d_bmap, &req);
+	if (ret < 0)
+		return ret;
+	direct->d_bmap.b_pops->bpop_commit_start_ptr(&direct->d_bmap,
+						     &req, blocknr);
+
+	binfo->bi_v.bi_vblocknr = nilfs_bmap_ptr_to_dptr(ptr);
+	binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+
+	return 0;
+}
+
+static int nilfs_direct_assign_p(struct nilfs_direct *direct,
+				 __u64 key, __u64 ptr,
+				 struct buffer_head **bh,
+				 sector_t blocknr,
+				 union nilfs_binfo *binfo)
+{
+	nilfs_direct_set_ptr(direct, key, blocknr);
+
+	binfo->bi_dat.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+	binfo->bi_dat.bi_level = 0;
+
+	return 0;
+}
+
+static int nilfs_direct_assign(struct nilfs_bmap *bmap,
+			       struct buffer_head **bh,
+			       sector_t blocknr,
+			       union nilfs_binfo *binfo)
+{
+	struct nilfs_direct *direct;
+	__u64 key;
+	__u64 ptr;
+
+	direct = (struct nilfs_direct *)bmap;
+	key = nilfs_bmap_data_get_key(bmap, *bh);
+	if (unlikely(key > NILFS_DIRECT_KEY_MAX)) {
+		printk(KERN_CRIT "%s: invalid key: %llu\n", __func__,
+		       (unsigned long long)key);
+		return -EINVAL;
+	}
+	ptr = nilfs_direct_get_ptr(direct, key);
+	if (unlikely(ptr == NILFS_BMAP_INVALID_PTR)) {
+		printk(KERN_CRIT "%s: invalid pointer: %llu\n", __func__,
+		       (unsigned long long)ptr);
+		return -EINVAL;
+	}
+
+	return direct->d_ops->dop_assign(direct, key, ptr, bh,
+					 blocknr, binfo);
+}
+
+static const struct nilfs_bmap_operations nilfs_direct_ops = {
+	.bop_lookup		=	nilfs_direct_lookup,
+	.bop_insert		=	nilfs_direct_insert,
+	.bop_delete		=	nilfs_direct_delete,
+	.bop_clear		=	NULL,
+
+	.bop_propagate		=	nilfs_direct_propagate,
+
+	.bop_lookup_dirty_buffers	=	NULL,
+
+	.bop_assign		=	nilfs_direct_assign,
+	.bop_mark		=	NULL,
+
+	.bop_last_key		=	nilfs_direct_last_key,
+	.bop_check_insert	=	nilfs_direct_check_insert,
+	.bop_check_delete	=	NULL,
+	.bop_gather_data	=	nilfs_direct_gather_data,
+};
+
+
+static const struct nilfs_direct_operations nilfs_direct_ops_v = {
+	.dop_find_target	=	nilfs_direct_find_target_v,
+	.dop_set_target		=	nilfs_direct_set_target_v,
+	.dop_propagate		=	nilfs_direct_propagate_v,
+	.dop_assign		=	nilfs_direct_assign_v,
+};
+
+static const struct nilfs_direct_operations nilfs_direct_ops_p = {
+	.dop_find_target	=	NULL,
+	.dop_set_target		=	NULL,
+	.dop_propagate		=	NULL,
+	.dop_assign		=	nilfs_direct_assign_p,
+};
+
+int nilfs_direct_init(struct nilfs_bmap *bmap, __u64 low, __u64 high)
+{
+	struct nilfs_direct *direct;
+
+	direct = (struct nilfs_direct *)bmap;
+	bmap->b_ops = &nilfs_direct_ops;
+	bmap->b_low = low;
+	bmap->b_high = high;
+	switch (bmap->b_inode->i_ino) {
+	case NILFS_DAT_INO:
+		direct->d_ops = &nilfs_direct_ops_p;
+		break;
+	default:
+		direct->d_ops = &nilfs_direct_ops_v;
+		break;
+	}
+
+	return 0;
+}
diff --git a/fs/nilfs2/direct.h b/fs/nilfs2/direct.h
new file mode 100644
index 00000000000..45d2c5cda81
--- /dev/null
+++ b/fs/nilfs2/direct.h
@@ -0,0 +1,78 @@
+/*
+ * direct.h - NILFS direct block pointer.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_DIRECT_H
+#define _NILFS_DIRECT_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include "bmap.h"
+
+
+struct nilfs_direct;
+
+/**
+ * struct nilfs_direct_operations - direct mapping operation table
+ */
+struct nilfs_direct_operations {
+	__u64 (*dop_find_target)(const struct nilfs_direct *, __u64);
+	void (*dop_set_target)(struct nilfs_direct *, __u64, __u64);
+	int (*dop_propagate)(struct nilfs_direct *, struct buffer_head *);
+	int (*dop_assign)(struct nilfs_direct *, __u64, __u64,
+			  struct buffer_head **, sector_t,
+			  union nilfs_binfo *);
+};
+
+/**
+ * struct nilfs_direct_node - direct node
+ * @dn_flags: flags
+ * @dn_pad: padding
+ */
+struct nilfs_direct_node {
+	__u8 dn_flags;
+	__u8 pad[7];
+};
+
+/**
+ * struct nilfs_direct - direct mapping
+ * @d_bmap: bmap structure
+ * @d_ops: direct mapping operation table
+ */
+struct nilfs_direct {
+	struct nilfs_bmap d_bmap;
+
+	/* direct-mapping-specific members */
+	const struct nilfs_direct_operations *d_ops;
+};
+
+
+#define NILFS_DIRECT_NBLOCKS	(NILFS_BMAP_SIZE / sizeof(__le64) - 1)
+#define NILFS_DIRECT_KEY_MIN	0
+#define NILFS_DIRECT_KEY_MAX	(NILFS_DIRECT_NBLOCKS - 1)
+
+
+int nilfs_direct_init(struct nilfs_bmap *, __u64, __u64);
+int nilfs_direct_delete_and_convert(struct nilfs_bmap *, __u64, __u64 *,
+				    __u64 *, int, __u64, __u64);
+
+
+#endif	/* _NILFS_DIRECT_H */
diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
new file mode 100644
index 00000000000..6bd84a0d823
--- /dev/null
+++ b/fs/nilfs2/file.c
@@ -0,0 +1,160 @@
+/*
+ * file.c - NILFS regular file handling primitives including fsync().
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Amagai Yoshiji <amagai@osrg.net>,
+ *            Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/writeback.h>
+#include "nilfs.h"
+#include "segment.h"
+
+int nilfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
+{
+	/*
+	 * Called from fsync() system call
+	 * This is the only entry point that can catch write and synch
+	 * timing for both data blocks and intermediate blocks.
+	 *
+	 * This function should be implemented when the writeback function
+	 * will be implemented.
+	 */
+	struct inode *inode = dentry->d_inode;
+	int err;
+
+	if (!nilfs_inode_dirty(inode))
+		return 0;
+
+	if (datasync)
+		err = nilfs_construct_dsync_segment(inode->i_sb, inode, 0,
+						    LLONG_MAX);
+	else
+		err = nilfs_construct_segment(inode->i_sb);
+
+	return err;
+}
+
+static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = vma->vm_file->f_dentry->d_inode;
+	struct nilfs_transaction_info ti;
+	int ret;
+
+	if (unlikely(nilfs_near_disk_full(NILFS_SB(inode->i_sb)->s_nilfs)))
+		return VM_FAULT_SIGBUS; /* -ENOSPC */
+
+	lock_page(page);
+	if (page->mapping != inode->i_mapping ||
+	    page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
+		unlock_page(page);
+		return VM_FAULT_NOPAGE; /* make the VM retry the fault */
+	}
+
+	/*
+	 * check to see if the page is mapped already (no holes)
+	 */
+	if (PageMappedToDisk(page)) {
+		unlock_page(page);
+		goto mapped;
+	}
+	if (page_has_buffers(page)) {
+		struct buffer_head *bh, *head;
+		int fully_mapped = 1;
+
+		bh = head = page_buffers(page);
+		do {
+			if (!buffer_mapped(bh)) {
+				fully_mapped = 0;
+				break;
+			}
+		} while (bh = bh->b_this_page, bh != head);
+
+		if (fully_mapped) {
+			SetPageMappedToDisk(page);
+			unlock_page(page);
+			goto mapped;
+		}
+	}
+	unlock_page(page);
+
+	/*
+	 * fill hole blocks
+	 */
+	ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
+	/* never returns -ENOMEM, but may return -ENOSPC */
+	if (unlikely(ret))
+		return VM_FAULT_SIGBUS;
+
+	ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
+	if (unlikely(ret)) {
+		nilfs_transaction_abort(inode->i_sb);
+		return ret;
+	}
+	nilfs_transaction_commit(inode->i_sb);
+
+ mapped:
+	SetPageChecked(page);
+	wait_on_page_writeback(page);
+	return 0;
+}
+
+struct vm_operations_struct nilfs_file_vm_ops = {
+	.fault		= filemap_fault,
+	.page_mkwrite	= nilfs_page_mkwrite,
+};
+
+static int nilfs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	file_accessed(file);
+	vma->vm_ops = &nilfs_file_vm_ops;
+	vma->vm_flags |= VM_CAN_NONLINEAR;
+	return 0;
+}
+
+/*
+ * We have mostly NULL's here: the current defaults are ok for
+ * the nilfs filesystem.
+ */
+struct file_operations nilfs_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+	.aio_read	= generic_file_aio_read,
+	.aio_write	= generic_file_aio_write,
+	.unlocked_ioctl	= nilfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= nilfs_ioctl,
+#endif	/* CONFIG_COMPAT */
+	.mmap		= nilfs_file_mmap,
+	.open		= generic_file_open,
+	/* .release	= nilfs_release_file, */
+	.fsync		= nilfs_sync_file,
+	.splice_read	= generic_file_splice_read,
+};
+
+struct inode_operations nilfs_file_inode_operations = {
+	.truncate	= nilfs_truncate,
+	.setattr	= nilfs_setattr,
+	.permission     = nilfs_permission,
+};
+
+/* end of file */
diff --git a/fs/nilfs2/gcdat.c b/fs/nilfs2/gcdat.c
new file mode 100644
index 00000000000..93383c5cee9
--- /dev/null
+++ b/fs/nilfs2/gcdat.c
@@ -0,0 +1,84 @@
+/*
+ * gcdat.c - NILFS shadow DAT inode for GC
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
+ *            and Ryusuke Konishi <ryusuke@osrg.net>.
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+#include "page.h"
+#include "mdt.h"
+
+int nilfs_init_gcdat_inode(struct the_nilfs *nilfs)
+{
+	struct inode *dat = nilfs->ns_dat, *gcdat = nilfs->ns_gc_dat;
+	struct nilfs_inode_info *dii = NILFS_I(dat), *gii = NILFS_I(gcdat);
+	int err;
+
+	gcdat->i_state = 0;
+	gcdat->i_blocks = dat->i_blocks;
+	gii->i_flags = dii->i_flags;
+	gii->i_state = dii->i_state | (1 << NILFS_I_GCDAT);
+	gii->i_cno = 0;
+	nilfs_bmap_init_gcdat(gii->i_bmap, dii->i_bmap);
+	err = nilfs_copy_dirty_pages(gcdat->i_mapping, dat->i_mapping);
+	if (unlikely(err))
+		return err;
+
+	return nilfs_copy_dirty_pages(&gii->i_btnode_cache,
+				      &dii->i_btnode_cache);
+}
+
+void nilfs_commit_gcdat_inode(struct the_nilfs *nilfs)
+{
+	struct inode *dat = nilfs->ns_dat, *gcdat = nilfs->ns_gc_dat;
+	struct nilfs_inode_info *dii = NILFS_I(dat), *gii = NILFS_I(gcdat);
+	struct address_space *mapping = dat->i_mapping;
+	struct address_space *gmapping = gcdat->i_mapping;
+
+	down_write(&NILFS_MDT(dat)->mi_sem);
+	dat->i_blocks = gcdat->i_blocks;
+	dii->i_flags = gii->i_flags;
+	dii->i_state = gii->i_state & ~(1 << NILFS_I_GCDAT);
+
+	nilfs_bmap_commit_gcdat(gii->i_bmap, dii->i_bmap);
+
+	nilfs_clear_dirty_pages(mapping);
+	nilfs_copy_back_pages(mapping, gmapping);
+	/* note: mdt dirty flags should be cleared by segctor. */
+
+	nilfs_clear_dirty_pages(&dii->i_btnode_cache);
+	nilfs_copy_back_pages(&dii->i_btnode_cache, &gii->i_btnode_cache);
+
+	up_write(&NILFS_MDT(dat)->mi_sem);
+}
+
+void nilfs_clear_gcdat_inode(struct the_nilfs *nilfs)
+{
+	struct inode *gcdat = nilfs->ns_gc_dat;
+	struct nilfs_inode_info *gii = NILFS_I(gcdat);
+
+	gcdat->i_state = I_CLEAR;
+	gii->i_flags = 0;
+
+	truncate_inode_pages(gcdat->i_mapping, 0);
+	truncate_inode_pages(&gii->i_btnode_cache, 0);
+}
diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
new file mode 100644
index 00000000000..19d2102b6a6
--- /dev/null
+++ b/fs/nilfs2/gcinode.c
@@ -0,0 +1,288 @@
+/*
+ * gcinode.c - dummy inodes to buffer blocks for garbage collection
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
+ *            and Ryusuke Konishi <ryusuke@osrg.net>.
+ * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
+ *
+ */
+/*
+ * This file adds the cache of on-disk blocks to be moved in garbage
+ * collection.  The disk blocks are held with dummy inodes (called
+ * gcinodes), and this file provides lookup function of the dummy
+ * inodes and their buffer read function.
+ *
+ * Since NILFS2 keeps up multiple checkpoints/snapshots accross GC, it
+ * has to treat blocks that belong to a same file but have different
+ * checkpoint numbers.  To avoid interference among generations, dummy
+ * inodes are managed separatly from actual inodes, and their lookup
+ * function (nilfs_gc_iget) is designed to be specified with a
+ * checkpoint number argument as well as an inode number.
+ *
+ * Buffers and pages held by the dummy inodes will be released each
+ * time after they are copied to a new log.  Dirty blocks made on the
+ * current generation and the blocks to be moved by GC never overlap
+ * because the dirty blocks make a new generation; they rather must be
+ * written individually.
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/hash.h>
+#include <linux/swap.h>
+#include "nilfs.h"
+#include "page.h"
+#include "mdt.h"
+#include "dat.h"
+#include "ifile.h"
+
+static struct address_space_operations def_gcinode_aops = {};
+/* XXX need def_gcinode_iops/fops? */
+
+/*
+ * nilfs_gccache_submit_read_data() - add data buffer and submit read request
+ * @inode - gc inode
+ * @blkoff - dummy offset treated as the key for the page cache
+ * @pbn - physical block number of the block
+ * @vbn - virtual block number of the block, 0 for non-virtual block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_data() registers the data buffer
+ * specified by @pbn to the GC pagecache with the key @blkoff.
+ * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
+ *
+ * Return Value: On success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - The block specified with @pbn does not exist.
+ */
+int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
+				   sector_t pbn, __u64 vbn,
+				   struct buffer_head **out_bh)
+{
+	struct buffer_head *bh;
+	int err;
+
+	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	if (buffer_uptodate(bh))
+		goto out;
+
+	if (pbn == 0) {
+		struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
+					  /* use original dat, not gc dat. */
+		err = nilfs_dat_translate(dat_inode, vbn, &pbn);
+		if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
+			brelse(bh);
+			goto failed;
+		}
+	}
+
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		goto out;
+	}
+
+	if (!buffer_mapped(bh)) {
+		bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
+		set_buffer_mapped(bh);
+	}
+	bh->b_blocknr = pbn;
+	bh->b_end_io = end_buffer_read_sync;
+	get_bh(bh);
+	submit_bh(READ, bh);
+	if (vbn)
+		bh->b_blocknr = vbn;
+ out:
+	err = 0;
+	*out_bh = bh;
+
+ failed:
+	unlock_page(bh->b_page);
+	page_cache_release(bh->b_page);
+	return err;
+}
+
+/*
+ * nilfs_gccache_submit_read_node() - add node buffer and submit read request
+ * @inode - gc inode
+ * @pbn - physical block number for the block
+ * @vbn - virtual block number for the block
+ * @out_bh - indirect pointer to a buffer_head struct to receive the results
+ *
+ * Description: nilfs_gccache_submit_read_node() registers the node buffer
+ * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
+ * caller to avoid translation of the disk block address.
+ *
+ * Return Value: On success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
+				   __u64 vbn, struct buffer_head **out_bh)
+{
+	int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
+					    vbn ? : pbn, pbn, out_bh, 0);
+	if (ret == -EEXIST) /* internal code (cache hit) */
+		ret = 0;
+	return ret;
+}
+
+int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
+{
+	wait_on_buffer(bh);
+	if (!buffer_uptodate(bh))
+		return -EIO;
+	if (buffer_dirty(bh))
+		return -EEXIST;
+
+	if (buffer_nilfs_node(bh))
+		nilfs_btnode_mark_dirty(bh);
+	else
+		nilfs_mdt_mark_buffer_dirty(bh);
+	return 0;
+}
+
+/*
+ * nilfs_init_gccache() - allocate and initialize gc_inode hash table
+ * @nilfs - the_nilfs
+ *
+ * Return Value: On success, 0.
+ * On error, a negative error code is returned.
+ */
+int nilfs_init_gccache(struct the_nilfs *nilfs)
+{
+	int loop;
+
+	BUG_ON(nilfs->ns_gc_inodes_h);
+
+	INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
+
+	nilfs->ns_gc_inodes_h =
+		kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
+			GFP_NOFS);
+	if (nilfs->ns_gc_inodes_h == NULL)
+		return -ENOMEM;
+
+	for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
+		INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
+	return 0;
+}
+
+/*
+ * nilfs_destroy_gccache() - free gc_inode hash table
+ * @nilfs - the nilfs
+ */
+void nilfs_destroy_gccache(struct the_nilfs *nilfs)
+{
+	if (nilfs->ns_gc_inodes_h) {
+		nilfs_remove_all_gcinode(nilfs);
+		kfree(nilfs->ns_gc_inodes_h);
+		nilfs->ns_gc_inodes_h = NULL;
+	}
+}
+
+static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
+				   __u64 cno)
+{
+	struct inode *inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS);
+	struct nilfs_inode_info *ii;
+
+	if (!inode)
+		return NULL;
+
+	inode->i_op = NULL;
+	inode->i_fop = NULL;
+	inode->i_mapping->a_ops = &def_gcinode_aops;
+
+	ii = NILFS_I(inode);
+	ii->i_cno = cno;
+	ii->i_flags = 0;
+	ii->i_state = 1 << NILFS_I_GCINODE;
+	ii->i_bh = NULL;
+	nilfs_bmap_init_gc(ii->i_bmap);
+
+	return inode;
+}
+
+static unsigned long ihash(ino_t ino, __u64 cno)
+{
+	return hash_long((unsigned long)((ino << 2) + cno),
+			 NILFS_GCINODE_HASH_BITS);
+}
+
+/*
+ * nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
+ */
+struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
+{
+	struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
+	struct hlist_node *node;
+	struct inode *inode;
+
+	hlist_for_each_entry(inode, node, head, i_hash) {
+		if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
+			return inode;
+	}
+
+	inode = alloc_gcinode(nilfs, ino, cno);
+	if (likely(inode)) {
+		hlist_add_head(&inode->i_hash, head);
+		list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
+	}
+	return inode;
+}
+
+/*
+ * nilfs_clear_gcinode() - clear and free a gc inode
+ */
+void nilfs_clear_gcinode(struct inode *inode)
+{
+	nilfs_mdt_clear(inode);
+	nilfs_mdt_destroy(inode);
+}
+
+/*
+ * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
+ */
+void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
+{
+	struct hlist_head *head = nilfs->ns_gc_inodes_h;
+	struct hlist_node *node, *n;
+	struct inode *inode;
+	int loop;
+
+	for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
+		hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
+			hlist_del_init(&inode->i_hash);
+			list_del_init(&NILFS_I(inode)->i_dirty);
+			nilfs_clear_gcinode(inode); /* might sleep */
+		}
+	}
+}
diff --git a/fs/nilfs2/ifile.c b/fs/nilfs2/ifile.c
new file mode 100644
index 00000000000..de86401f209
--- /dev/null
+++ b/fs/nilfs2/ifile.c
@@ -0,0 +1,150 @@
+/*
+ * ifile.c - NILFS inode file
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Amagai Yoshiji <amagai@osrg.net>.
+ * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+#include "mdt.h"
+#include "alloc.h"
+#include "ifile.h"
+
+/**
+ * nilfs_ifile_create_inode - create a new disk inode
+ * @ifile: ifile inode
+ * @out_ino: pointer to a variable to store inode number
+ * @out_bh: buffer_head contains newly allocated disk inode
+ *
+ * Return Value: On success, 0 is returned and the newly allocated inode
+ * number is stored in the place pointed by @ino, and buffer_head pointer
+ * that contains newly allocated disk inode structure is stored in the
+ * place pointed by @out_bh
+ * On error, one of the following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOSPC - No inode left.
+ */
+int nilfs_ifile_create_inode(struct inode *ifile, ino_t *out_ino,
+			     struct buffer_head **out_bh)
+{
+	struct nilfs_palloc_req req;
+	int ret;
+
+	req.pr_entry_nr = 0;  /* 0 says find free inode from beginning of
+				 a group. dull code!! */
+	req.pr_entry_bh = NULL;
+
+	ret = nilfs_palloc_prepare_alloc_entry(ifile, &req);
+	if (!ret) {
+		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 1,
+						   &req.pr_entry_bh);
+		if (ret < 0)
+			nilfs_palloc_abort_alloc_entry(ifile, &req);
+	}
+	if (ret < 0) {
+		brelse(req.pr_entry_bh);
+		return ret;
+	}
+	nilfs_palloc_commit_alloc_entry(ifile, &req);
+	nilfs_mdt_mark_buffer_dirty(req.pr_entry_bh);
+	nilfs_mdt_mark_dirty(ifile);
+	*out_ino = (ino_t)req.pr_entry_nr;
+	*out_bh = req.pr_entry_bh;
+	return 0;
+}
+
+/**
+ * nilfs_ifile_delete_inode - delete a disk inode
+ * @ifile: ifile inode
+ * @ino: inode number
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - The inode number @ino have not been allocated.
+ */
+int nilfs_ifile_delete_inode(struct inode *ifile, ino_t ino)
+{
+	struct nilfs_palloc_req req = {
+		.pr_entry_nr = ino, .pr_entry_bh = NULL
+	};
+	struct nilfs_inode *raw_inode;
+	void *kaddr;
+	int ret;
+
+	ret = nilfs_palloc_prepare_free_entry(ifile, &req);
+	if (!ret) {
+		ret = nilfs_palloc_get_entry_block(ifile, req.pr_entry_nr, 0,
+						   &req.pr_entry_bh);
+		if (ret < 0)
+			nilfs_palloc_abort_free_entry(ifile, &req);
+	}
+	if (ret < 0) {
+		brelse(req.pr_entry_bh);
+		return ret;
+	}
+
+	kaddr = kmap_atomic(req.pr_entry_bh->b_page, KM_USER0);
+	raw_inode = nilfs_palloc_block_get_entry(ifile, req.pr_entry_nr,
+						 req.pr_entry_bh, kaddr);
+	raw_inode->i_flags = 0;
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_mdt_mark_buffer_dirty(req.pr_entry_bh);
+	brelse(req.pr_entry_bh);
+
+	nilfs_palloc_commit_free_entry(ifile, &req);
+
+	return 0;
+}
+
+int nilfs_ifile_get_inode_block(struct inode *ifile, ino_t ino,
+				struct buffer_head **out_bh)
+{
+	struct super_block *sb = ifile->i_sb;
+	int err;
+
+	if (unlikely(!NILFS_VALID_INODE(sb, ino))) {
+		nilfs_error(sb, __func__, "bad inode number: %lu",
+			    (unsigned long) ino);
+		return -EINVAL;
+	}
+
+	err = nilfs_palloc_get_entry_block(ifile, ino, 0, out_bh);
+	if (unlikely(err)) {
+		if (err == -EINVAL)
+			nilfs_error(sb, __func__, "ifile is broken");
+		else
+			nilfs_warning(sb, __func__,
+				      "unable to read inode: %lu",
+				      (unsigned long) ino);
+	}
+	return err;
+}
diff --git a/fs/nilfs2/ifile.h b/fs/nilfs2/ifile.h
new file mode 100644
index 00000000000..5d30a35679b
--- /dev/null
+++ b/fs/nilfs2/ifile.h
@@ -0,0 +1,53 @@
+/*
+ * ifile.h - NILFS inode file
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Amagai Yoshiji <amagai@osrg.net>
+ * Revised by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#ifndef _NILFS_IFILE_H
+#define _NILFS_IFILE_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+#include "mdt.h"
+#include "alloc.h"
+
+#define NILFS_IFILE_GFP  NILFS_MDT_GFP
+
+static inline struct nilfs_inode *
+nilfs_ifile_map_inode(struct inode *ifile, ino_t ino, struct buffer_head *ibh)
+{
+	void *kaddr = kmap(ibh->b_page);
+	return nilfs_palloc_block_get_entry(ifile, ino, ibh, kaddr);
+}
+
+static inline void nilfs_ifile_unmap_inode(struct inode *ifile, ino_t ino,
+					   struct buffer_head *ibh)
+{
+	kunmap(ibh->b_page);
+}
+
+int nilfs_ifile_create_inode(struct inode *, ino_t *, struct buffer_head **);
+int nilfs_ifile_delete_inode(struct inode *, ino_t);
+int nilfs_ifile_get_inode_block(struct inode *, ino_t, struct buffer_head **);
+
+#endif	/* _NILFS_IFILE_H */
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
new file mode 100644
index 00000000000..49ab4a49bb4
--- /dev/null
+++ b/fs/nilfs2/inode.c
@@ -0,0 +1,785 @@
+/*
+ * inode.c - NILFS inode operations.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/uio.h>
+#include "nilfs.h"
+#include "segment.h"
+#include "page.h"
+#include "mdt.h"
+#include "cpfile.h"
+#include "ifile.h"
+
+
+/**
+ * nilfs_get_block() - get a file block on the filesystem (callback function)
+ * @inode - inode struct of the target file
+ * @blkoff - file block number
+ * @bh_result - buffer head to be mapped on
+ * @create - indicate whether allocating the block or not when it has not
+ *      been allocated yet.
+ *
+ * This function does not issue actual read request of the specified data
+ * block. It is done by VFS.
+ * Bulk read for direct-io is not supported yet. (should be supported)
+ */
+int nilfs_get_block(struct inode *inode, sector_t blkoff,
+		    struct buffer_head *bh_result, int create)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	unsigned long blknum = 0;
+	int err = 0, ret;
+	struct inode *dat = nilfs_dat_inode(NILFS_I_NILFS(inode));
+
+	/* This exclusion control is a workaround; should be revised */
+	down_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	ret = nilfs_bmap_lookup(ii->i_bmap, (unsigned long)blkoff, &blknum);
+	up_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	if (ret == 0) {	/* found */
+		map_bh(bh_result, inode->i_sb, blknum);
+		goto out;
+	}
+	/* data block was not found */
+	if (ret == -ENOENT && create) {
+		struct nilfs_transaction_info ti;
+
+		bh_result->b_blocknr = 0;
+		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
+		if (unlikely(err))
+			goto out;
+		err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
+					(unsigned long)bh_result);
+		if (unlikely(err != 0)) {
+			if (err == -EEXIST) {
+				/*
+				 * The get_block() function could be called
+				 * from multiple callers for an inode.
+				 * However, the page having this block must
+				 * be locked in this case.
+				 */
+				printk(KERN_WARNING
+				       "nilfs_get_block: a race condition "
+				       "while inserting a data block. "
+				       "(inode number=%lu, file block "
+				       "offset=%llu)\n",
+				       inode->i_ino,
+				       (unsigned long long)blkoff);
+				err = 0;
+			} else if (err == -EINVAL) {
+				nilfs_error(inode->i_sb, __func__,
+					    "broken bmap (inode=%lu)\n",
+					    inode->i_ino);
+				err = -EIO;
+			}
+			nilfs_transaction_abort(inode->i_sb);
+			goto out;
+		}
+		nilfs_transaction_commit(inode->i_sb); /* never fails */
+		/* Error handling should be detailed */
+		set_buffer_new(bh_result);
+		map_bh(bh_result, inode->i_sb, 0); /* dbn must be changed
+						      to proper value */
+	} else if (ret == -ENOENT) {
+		/* not found is not error (e.g. hole); must return without
+		   the mapped state flag. */
+		;
+	} else {
+		err = ret;
+	}
+
+ out:
+	return err;
+}
+
+/**
+ * nilfs_readpage() - implement readpage() method of nilfs_aops {}
+ * address_space_operations.
+ * @file - file struct of the file to be read
+ * @page - the page to be read
+ */
+static int nilfs_readpage(struct file *file, struct page *page)
+{
+	return mpage_readpage(page, nilfs_get_block);
+}
+
+/**
+ * nilfs_readpages() - implement readpages() method of nilfs_aops {}
+ * address_space_operations.
+ * @file - file struct of the file to be read
+ * @mapping - address_space struct used for reading multiple pages
+ * @pages - the pages to be read
+ * @nr_pages - number of pages to be read
+ */
+static int nilfs_readpages(struct file *file, struct address_space *mapping,
+			   struct list_head *pages, unsigned nr_pages)
+{
+	return mpage_readpages(mapping, pages, nr_pages, nilfs_get_block);
+}
+
+static int nilfs_writepages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	int err = 0;
+
+	if (wbc->sync_mode == WB_SYNC_ALL)
+		err = nilfs_construct_dsync_segment(inode->i_sb, inode,
+						    wbc->range_start,
+						    wbc->range_end);
+	return err;
+}
+
+static int nilfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	int err;
+
+	redirty_page_for_writepage(wbc, page);
+	unlock_page(page);
+
+	if (wbc->sync_mode == WB_SYNC_ALL) {
+		err = nilfs_construct_segment(inode->i_sb);
+		if (unlikely(err))
+			return err;
+	} else if (wbc->for_reclaim)
+		nilfs_flush_segment(inode->i_sb, inode->i_ino);
+
+	return 0;
+}
+
+static int nilfs_set_page_dirty(struct page *page)
+{
+	int ret = __set_page_dirty_buffers(page);
+
+	if (ret) {
+		struct inode *inode = page->mapping->host;
+		struct nilfs_sb_info *sbi = NILFS_SB(inode->i_sb);
+		unsigned nr_dirty = 1 << (PAGE_SHIFT - inode->i_blkbits);
+
+		nilfs_set_file_dirty(sbi, inode, nr_dirty);
+	}
+	return ret;
+}
+
+static int nilfs_write_begin(struct file *file, struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned flags,
+			     struct page **pagep, void **fsdata)
+
+{
+	struct inode *inode = mapping->host;
+	int err = nilfs_transaction_begin(inode->i_sb, NULL, 1);
+
+	if (unlikely(err))
+		return err;
+
+	*pagep = NULL;
+	err = block_write_begin(file, mapping, pos, len, flags, pagep,
+				fsdata, nilfs_get_block);
+	if (unlikely(err))
+		nilfs_transaction_abort(inode->i_sb);
+	return err;
+}
+
+static int nilfs_write_end(struct file *file, struct address_space *mapping,
+			   loff_t pos, unsigned len, unsigned copied,
+			   struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
+	unsigned nr_dirty;
+	int err;
+
+	nr_dirty = nilfs_page_count_clean_buffers(page, start,
+						  start + copied);
+	copied = generic_write_end(file, mapping, pos, len, copied, page,
+				   fsdata);
+	nilfs_set_file_dirty(NILFS_SB(inode->i_sb), inode, nr_dirty);
+	err = nilfs_transaction_commit(inode->i_sb);
+	return err ? : copied;
+}
+
+static ssize_t
+nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+		loff_t offset, unsigned long nr_segs)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t size;
+
+	if (rw == WRITE)
+		return 0;
+
+	/* Needs synchronization with the cleaner */
+	size = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
+				  offset, nr_segs, nilfs_get_block, NULL);
+	return size;
+}
+
+struct address_space_operations nilfs_aops = {
+	.writepage		= nilfs_writepage,
+	.readpage		= nilfs_readpage,
+	/* .sync_page		= nilfs_sync_page, */
+	.writepages		= nilfs_writepages,
+	.set_page_dirty		= nilfs_set_page_dirty,
+	.readpages		= nilfs_readpages,
+	.write_begin		= nilfs_write_begin,
+	.write_end		= nilfs_write_end,
+	/* .releasepage		= nilfs_releasepage, */
+	.invalidatepage		= block_invalidatepage,
+	.direct_IO		= nilfs_direct_IO,
+};
+
+struct inode *nilfs_new_inode(struct inode *dir, int mode)
+{
+	struct super_block *sb = dir->i_sb;
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct inode *inode;
+	struct nilfs_inode_info *ii;
+	int err = -ENOMEM;
+	ino_t ino;
+
+	inode = new_inode(sb);
+	if (unlikely(!inode))
+		goto failed;
+
+	mapping_set_gfp_mask(inode->i_mapping,
+			     mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
+
+	ii = NILFS_I(inode);
+	ii->i_state = 1 << NILFS_I_NEW;
+
+	err = nilfs_ifile_create_inode(sbi->s_ifile, &ino, &ii->i_bh);
+	if (unlikely(err))
+		goto failed_ifile_create_inode;
+	/* reference count of i_bh inherits from nilfs_mdt_read_block() */
+
+	atomic_inc(&sbi->s_inodes_count);
+
+	inode->i_uid = current_fsuid();
+	if (dir->i_mode & S_ISGID) {
+		inode->i_gid = dir->i_gid;
+		if (S_ISDIR(mode))
+			mode |= S_ISGID;
+	} else
+		inode->i_gid = current_fsgid();
+
+	inode->i_mode = mode;
+	inode->i_ino = ino;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+
+	if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) {
+		err = nilfs_bmap_read(ii->i_bmap, NULL);
+		if (err < 0)
+			goto failed_bmap;
+
+		set_bit(NILFS_I_BMAP, &ii->i_state);
+		/* No lock is needed; iget() ensures it. */
+	}
+
+	ii->i_flags = NILFS_I(dir)->i_flags;
+	if (S_ISLNK(mode))
+		ii->i_flags &= ~(NILFS_IMMUTABLE_FL | NILFS_APPEND_FL);
+	if (!S_ISDIR(mode))
+		ii->i_flags &= ~NILFS_DIRSYNC_FL;
+
+	/* ii->i_file_acl = 0; */
+	/* ii->i_dir_acl = 0; */
+	ii->i_dir_start_lookup = 0;
+#ifdef CONFIG_NILFS_FS_POSIX_ACL
+	ii->i_acl = NULL;
+	ii->i_default_acl = NULL;
+#endif
+	ii->i_cno = 0;
+	nilfs_set_inode_flags(inode);
+	spin_lock(&sbi->s_next_gen_lock);
+	inode->i_generation = sbi->s_next_generation++;
+	spin_unlock(&sbi->s_next_gen_lock);
+	insert_inode_hash(inode);
+
+	err = nilfs_init_acl(inode, dir);
+	if (unlikely(err))
+		goto failed_acl; /* never occur. When supporting
+				    nilfs_init_acl(), proper cancellation of
+				    above jobs should be considered */
+
+	mark_inode_dirty(inode);
+	return inode;
+
+ failed_acl:
+ failed_bmap:
+	inode->i_nlink = 0;
+	iput(inode);  /* raw_inode will be deleted through
+			 generic_delete_inode() */
+	goto failed;
+
+ failed_ifile_create_inode:
+	make_bad_inode(inode);
+	iput(inode);  /* if i_nlink == 1, generic_forget_inode() will be
+			 called */
+ failed:
+	return ERR_PTR(err);
+}
+
+void nilfs_free_inode(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+
+	clear_inode(inode);
+	/* XXX: check error code? Is there any thing I can do? */
+	(void) nilfs_ifile_delete_inode(sbi->s_ifile, inode->i_ino);
+	atomic_dec(&sbi->s_inodes_count);
+}
+
+void nilfs_set_inode_flags(struct inode *inode)
+{
+	unsigned int flags = NILFS_I(inode)->i_flags;
+
+	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
+			    S_DIRSYNC);
+	if (flags & NILFS_SYNC_FL)
+		inode->i_flags |= S_SYNC;
+	if (flags & NILFS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (flags & NILFS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+#ifndef NILFS_ATIME_DISABLE
+	if (flags & NILFS_NOATIME_FL)
+#endif
+		inode->i_flags |= S_NOATIME;
+	if (flags & NILFS_DIRSYNC_FL)
+		inode->i_flags |= S_DIRSYNC;
+	mapping_set_gfp_mask(inode->i_mapping,
+			     mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
+}
+
+int nilfs_read_inode_common(struct inode *inode,
+			    struct nilfs_inode *raw_inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	int err;
+
+	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
+	inode->i_uid = (uid_t)le32_to_cpu(raw_inode->i_uid);
+	inode->i_gid = (gid_t)le32_to_cpu(raw_inode->i_gid);
+	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
+	inode->i_size = le64_to_cpu(raw_inode->i_size);
+	inode->i_atime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+	inode->i_ctime.tv_sec = le64_to_cpu(raw_inode->i_ctime);
+	inode->i_mtime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+	inode->i_atime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+	inode->i_ctime.tv_nsec = le32_to_cpu(raw_inode->i_ctime_nsec);
+	inode->i_mtime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+	if (inode->i_nlink == 0 && inode->i_mode == 0)
+		return -EINVAL; /* this inode is deleted */
+
+	inode->i_blocks = le64_to_cpu(raw_inode->i_blocks);
+	ii->i_flags = le32_to_cpu(raw_inode->i_flags);
+#if 0
+	ii->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
+	ii->i_dir_acl = S_ISREG(inode->i_mode) ?
+		0 : le32_to_cpu(raw_inode->i_dir_acl);
+#endif
+	ii->i_cno = 0;
+	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
+
+	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+	    S_ISLNK(inode->i_mode)) {
+		err = nilfs_bmap_read(ii->i_bmap, raw_inode);
+		if (err < 0)
+			return err;
+		set_bit(NILFS_I_BMAP, &ii->i_state);
+		/* No lock is needed; iget() ensures it. */
+	}
+	return 0;
+}
+
+static int __nilfs_read_inode(struct super_block *sb, unsigned long ino,
+			      struct inode *inode)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct inode *dat = nilfs_dat_inode(sbi->s_nilfs);
+	struct buffer_head *bh;
+	struct nilfs_inode *raw_inode;
+	int err;
+
+	down_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	err = nilfs_ifile_get_inode_block(sbi->s_ifile, ino, &bh);
+	if (unlikely(err))
+		goto bad_inode;
+
+	raw_inode = nilfs_ifile_map_inode(sbi->s_ifile, ino, bh);
+
+#ifdef CONFIG_NILFS_FS_POSIX_ACL
+	ii->i_acl = NILFS_ACL_NOT_CACHED;
+	ii->i_default_acl = NILFS_ACL_NOT_CACHED;
+#endif
+	if (nilfs_read_inode_common(inode, raw_inode))
+		goto failed_unmap;
+
+	if (S_ISREG(inode->i_mode)) {
+		inode->i_op = &nilfs_file_inode_operations;
+		inode->i_fop = &nilfs_file_operations;
+		inode->i_mapping->a_ops = &nilfs_aops;
+	} else if (S_ISDIR(inode->i_mode)) {
+		inode->i_op = &nilfs_dir_inode_operations;
+		inode->i_fop = &nilfs_dir_operations;
+		inode->i_mapping->a_ops = &nilfs_aops;
+	} else if (S_ISLNK(inode->i_mode)) {
+		inode->i_op = &nilfs_symlink_inode_operations;
+		inode->i_mapping->a_ops = &nilfs_aops;
+	} else {
+		inode->i_op = &nilfs_special_inode_operations;
+		init_special_inode(
+			inode, inode->i_mode,
+			new_decode_dev(le64_to_cpu(raw_inode->i_device_code)));
+	}
+	nilfs_ifile_unmap_inode(sbi->s_ifile, ino, bh);
+	brelse(bh);
+	up_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	nilfs_set_inode_flags(inode);
+	return 0;
+
+ failed_unmap:
+	nilfs_ifile_unmap_inode(sbi->s_ifile, ino, bh);
+	brelse(bh);
+
+ bad_inode:
+	up_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	return err;
+}
+
+struct inode *nilfs_iget(struct super_block *sb, unsigned long ino)
+{
+	struct inode *inode;
+	int err;
+
+	inode = iget_locked(sb, ino);
+	if (unlikely(!inode))
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	err = __nilfs_read_inode(sb, ino, inode);
+	if (unlikely(err)) {
+		iget_failed(inode);
+		return ERR_PTR(err);
+	}
+	unlock_new_inode(inode);
+	return inode;
+}
+
+void nilfs_write_inode_common(struct inode *inode,
+			      struct nilfs_inode *raw_inode, int has_bmap)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
+	raw_inode->i_uid = cpu_to_le32(inode->i_uid);
+	raw_inode->i_gid = cpu_to_le32(inode->i_gid);
+	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
+	raw_inode->i_size = cpu_to_le64(inode->i_size);
+	raw_inode->i_ctime = cpu_to_le64(inode->i_ctime.tv_sec);
+	raw_inode->i_mtime = cpu_to_le64(inode->i_mtime.tv_sec);
+	raw_inode->i_ctime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
+	raw_inode->i_mtime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
+	raw_inode->i_blocks = cpu_to_le64(inode->i_blocks);
+
+	raw_inode->i_flags = cpu_to_le32(ii->i_flags);
+	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
+
+	if (has_bmap)
+		nilfs_bmap_write(ii->i_bmap, raw_inode);
+	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
+		raw_inode->i_device_code =
+			cpu_to_le64(new_encode_dev(inode->i_rdev));
+	/* When extending inode, nilfs->ns_inode_size should be checked
+	   for substitutions of appended fields */
+}
+
+void nilfs_update_inode(struct inode *inode, struct buffer_head *ibh)
+{
+	ino_t ino = inode->i_ino;
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_inode *raw_inode;
+
+	raw_inode = nilfs_ifile_map_inode(sbi->s_ifile, ino, ibh);
+
+	/* The buffer is guarded with lock_buffer() by the caller */
+	if (test_and_clear_bit(NILFS_I_NEW, &ii->i_state))
+		memset(raw_inode, 0, NILFS_MDT(sbi->s_ifile)->mi_entry_size);
+	set_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
+
+	nilfs_write_inode_common(inode, raw_inode, 0);
+		/* XXX: call with has_bmap = 0 is a workaround to avoid
+		   deadlock of bmap. This delays update of i_bmap to just
+		   before writing */
+	nilfs_ifile_unmap_inode(sbi->s_ifile, ino, ibh);
+}
+
+#define NILFS_MAX_TRUNCATE_BLOCKS	16384  /* 64MB for 4KB block */
+
+static void nilfs_truncate_bmap(struct nilfs_inode_info *ii,
+				unsigned long from)
+{
+	unsigned long b;
+	int ret;
+
+	if (!test_bit(NILFS_I_BMAP, &ii->i_state))
+		return;
+ repeat:
+	ret = nilfs_bmap_last_key(ii->i_bmap, &b);
+	if (ret == -ENOENT)
+		return;
+	else if (ret < 0)
+		goto failed;
+
+	if (b < from)
+		return;
+
+	b -= min_t(unsigned long, NILFS_MAX_TRUNCATE_BLOCKS, b - from);
+	ret = nilfs_bmap_truncate(ii->i_bmap, b);
+	nilfs_relax_pressure_in_lock(ii->vfs_inode.i_sb);
+	if (!ret || (ret == -ENOMEM &&
+		     nilfs_bmap_truncate(ii->i_bmap, b) == 0))
+		goto repeat;
+
+ failed:
+	if (ret == -EINVAL)
+		nilfs_error(ii->vfs_inode.i_sb, __func__,
+			    "bmap is broken (ino=%lu)", ii->vfs_inode.i_ino);
+	else
+		nilfs_warning(ii->vfs_inode.i_sb, __func__,
+			      "failed to truncate bmap (ino=%lu, err=%d)",
+			      ii->vfs_inode.i_ino, ret);
+}
+
+void nilfs_truncate(struct inode *inode)
+{
+	unsigned long blkoff;
+	unsigned int blocksize;
+	struct nilfs_transaction_info ti;
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	if (!test_bit(NILFS_I_BMAP, &ii->i_state))
+		return;
+	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+		return;
+
+	blocksize = sb->s_blocksize;
+	blkoff = (inode->i_size + blocksize - 1) >> sb->s_blocksize_bits;
+	nilfs_transaction_begin(sb, &ti, 0); /* never fails */
+
+	block_truncate_page(inode->i_mapping, inode->i_size, nilfs_get_block);
+
+	nilfs_truncate_bmap(ii, blkoff);
+
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+	if (IS_SYNC(inode))
+		nilfs_set_transaction_flag(NILFS_TI_SYNC);
+
+	nilfs_set_file_dirty(NILFS_SB(sb), inode, 0);
+	nilfs_transaction_commit(sb);
+	/* May construct a logical segment and may fail in sync mode.
+	   But truncate has no return value. */
+}
+
+void nilfs_delete_inode(struct inode *inode)
+{
+	struct nilfs_transaction_info ti;
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	if (unlikely(is_bad_inode(inode))) {
+		if (inode->i_data.nrpages)
+			truncate_inode_pages(&inode->i_data, 0);
+		clear_inode(inode);
+		return;
+	}
+	nilfs_transaction_begin(sb, &ti, 0); /* never fails */
+
+	if (inode->i_data.nrpages)
+		truncate_inode_pages(&inode->i_data, 0);
+
+	nilfs_truncate_bmap(ii, 0);
+	nilfs_free_inode(inode);
+	/* nilfs_free_inode() marks inode buffer dirty */
+	if (IS_SYNC(inode))
+		nilfs_set_transaction_flag(NILFS_TI_SYNC);
+	nilfs_transaction_commit(sb);
+	/* May construct a logical segment and may fail in sync mode.
+	   But delete_inode has no return value. */
+}
+
+int nilfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct nilfs_transaction_info ti;
+	struct inode *inode = dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
+	int err;
+
+	err = inode_change_ok(inode, iattr);
+	if (err)
+		return err;
+
+	err = nilfs_transaction_begin(sb, &ti, 0);
+	if (unlikely(err))
+		return err;
+	err = inode_setattr(inode, iattr);
+	if (!err && (iattr->ia_valid & ATTR_MODE))
+		err = nilfs_acl_chmod(inode);
+	if (likely(!err))
+		err = nilfs_transaction_commit(sb);
+	else
+		nilfs_transaction_abort(sb);
+
+	return err;
+}
+
+int nilfs_load_inode_block(struct nilfs_sb_info *sbi, struct inode *inode,
+			   struct buffer_head **pbh)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	int err;
+
+	spin_lock(&sbi->s_inode_lock);
+	/* Caller of this function MUST lock s_inode_lock */
+	if (ii->i_bh == NULL) {
+		spin_unlock(&sbi->s_inode_lock);
+		err = nilfs_ifile_get_inode_block(sbi->s_ifile, inode->i_ino,
+						  pbh);
+		if (unlikely(err))
+			return err;
+		spin_lock(&sbi->s_inode_lock);
+		if (ii->i_bh == NULL)
+			ii->i_bh = *pbh;
+		else {
+			brelse(*pbh);
+			*pbh = ii->i_bh;
+		}
+	} else
+		*pbh = ii->i_bh;
+
+	get_bh(*pbh);
+	spin_unlock(&sbi->s_inode_lock);
+	return 0;
+}
+
+int nilfs_inode_dirty(struct inode *inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	struct nilfs_sb_info *sbi = NILFS_SB(inode->i_sb);
+	int ret = 0;
+
+	if (!list_empty(&ii->i_dirty)) {
+		spin_lock(&sbi->s_inode_lock);
+		ret = test_bit(NILFS_I_DIRTY, &ii->i_state) ||
+			test_bit(NILFS_I_BUSY, &ii->i_state);
+		spin_unlock(&sbi->s_inode_lock);
+	}
+	return ret;
+}
+
+int nilfs_set_file_dirty(struct nilfs_sb_info *sbi, struct inode *inode,
+			 unsigned nr_dirty)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	atomic_add(nr_dirty, &sbi->s_nilfs->ns_ndirtyblks);
+
+	if (test_and_set_bit(NILFS_I_DIRTY, &ii->i_state))
+		return 0;
+
+	spin_lock(&sbi->s_inode_lock);
+	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
+	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
+		/* Because this routine may race with nilfs_dispose_list(),
+		   we have to check NILFS_I_QUEUED here, too. */
+		if (list_empty(&ii->i_dirty) && igrab(inode) == NULL) {
+			/* This will happen when somebody is freeing
+			   this inode. */
+			nilfs_warning(sbi->s_super, __func__,
+				      "cannot get inode (ino=%lu)\n",
+				      inode->i_ino);
+			spin_unlock(&sbi->s_inode_lock);
+			return -EINVAL; /* NILFS_I_DIRTY may remain for
+					   freeing inode */
+		}
+		list_del(&ii->i_dirty);
+		list_add_tail(&ii->i_dirty, &sbi->s_dirty_files);
+		set_bit(NILFS_I_QUEUED, &ii->i_state);
+	}
+	spin_unlock(&sbi->s_inode_lock);
+	return 0;
+}
+
+int nilfs_mark_inode_dirty(struct inode *inode)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(inode->i_sb);
+	struct buffer_head *ibh;
+	int err;
+
+	err = nilfs_load_inode_block(sbi, inode, &ibh);
+	if (unlikely(err)) {
+		nilfs_warning(inode->i_sb, __func__,
+			      "failed to reget inode block.\n");
+		return err;
+	}
+	lock_buffer(ibh);
+	nilfs_update_inode(inode, ibh);
+	unlock_buffer(ibh);
+	nilfs_mdt_mark_buffer_dirty(ibh);
+	nilfs_mdt_mark_dirty(sbi->s_ifile);
+	brelse(ibh);
+	return 0;
+}
+
+/**
+ * nilfs_dirty_inode - reflect changes on given inode to an inode block.
+ * @inode: inode of the file to be registered.
+ *
+ * nilfs_dirty_inode() loads a inode block containing the specified
+ * @inode and copies data from a nilfs_inode to a corresponding inode
+ * entry in the inode block. This operation is excluded from the segment
+ * construction. This function can be called both as a single operation
+ * and as a part of indivisible file operations.
+ */
+void nilfs_dirty_inode(struct inode *inode)
+{
+	struct nilfs_transaction_info ti;
+
+	if (is_bad_inode(inode)) {
+		nilfs_warning(inode->i_sb, __func__,
+			      "tried to mark bad_inode dirty. ignored.\n");
+		dump_stack();
+		return;
+	}
+	nilfs_transaction_begin(inode->i_sb, &ti, 0);
+	nilfs_mark_inode_dirty(inode);
+	nilfs_transaction_commit(inode->i_sb); /* never fails */
+}
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
new file mode 100644
index 00000000000..108d281ebca
--- /dev/null
+++ b/fs/nilfs2/ioctl.c
@@ -0,0 +1,654 @@
+/*
+ * ioctl.c - NILFS ioctl operations.
+ *
+ * Copyright (C) 2007, 2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/fs.h>
+#include <linux/wait.h>
+#include <linux/smp_lock.h>	/* lock_kernel(), unlock_kernel() */
+#include <linux/capability.h>	/* capable() */
+#include <linux/uaccess.h>	/* copy_from_user(), copy_to_user() */
+#include <linux/nilfs2_fs.h>
+#include "nilfs.h"
+#include "segment.h"
+#include "bmap.h"
+#include "cpfile.h"
+#include "sufile.h"
+#include "dat.h"
+
+
+static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
+				 struct nilfs_argv *argv, int dir,
+				 ssize_t (*dofunc)(struct the_nilfs *,
+						   __u64 *, int,
+						   void *, size_t, size_t))
+{
+	void *buf;
+	void __user *base = (void __user *)(unsigned long)argv->v_base;
+	size_t maxmembs, total, n;
+	ssize_t nr;
+	int ret, i;
+	__u64 pos, ppos;
+
+	if (argv->v_nmembs == 0)
+		return 0;
+
+	if (argv->v_size > PAGE_SIZE)
+		return -EINVAL;
+
+	buf = (void *)__get_free_pages(GFP_NOFS, 0);
+	if (unlikely(!buf))
+		return -ENOMEM;
+	maxmembs = PAGE_SIZE / argv->v_size;
+
+	ret = 0;
+	total = 0;
+	pos = argv->v_index;
+	for (i = 0; i < argv->v_nmembs; i += n) {
+		n = (argv->v_nmembs - i < maxmembs) ?
+			argv->v_nmembs - i : maxmembs;
+		if ((dir & _IOC_WRITE) &&
+		    copy_from_user(buf, base + argv->v_size * i,
+				   argv->v_size * n)) {
+			ret = -EFAULT;
+			break;
+		}
+		ppos = pos;
+		nr = dofunc(nilfs, &pos, argv->v_flags, buf, argv->v_size,
+			       n);
+		if (nr < 0) {
+			ret = nr;
+			break;
+		}
+		if ((dir & _IOC_READ) &&
+		    copy_to_user(base + argv->v_size * i, buf,
+				 argv->v_size * nr)) {
+			ret = -EFAULT;
+			break;
+		}
+		total += nr;
+		if ((size_t)nr < n)
+			break;
+		if (pos == ppos)
+			pos += n;
+	}
+	argv->v_nmembs = total;
+
+	free_pages((unsigned long)buf, 0);
+	return ret;
+}
+
+static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
+				     unsigned int cmd, void __user *argp)
+{
+	struct inode *cpfile = NILFS_SB(inode->i_sb)->s_nilfs->ns_cpfile;
+	struct nilfs_transaction_info ti;
+	struct nilfs_cpmode cpmode;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (copy_from_user(&cpmode, argp, sizeof(cpmode)))
+		return -EFAULT;
+
+	nilfs_transaction_begin(inode->i_sb, &ti, 0);
+	ret = nilfs_cpfile_change_cpmode(
+		cpfile, cpmode.cm_cno, cpmode.cm_mode);
+	if (unlikely(ret < 0)) {
+		nilfs_transaction_abort(inode->i_sb);
+		return ret;
+	}
+	nilfs_transaction_commit(inode->i_sb); /* never fails */
+	return ret;
+}
+
+static int
+nilfs_ioctl_delete_checkpoint(struct inode *inode, struct file *filp,
+			      unsigned int cmd, void __user *argp)
+{
+	struct inode *cpfile = NILFS_SB(inode->i_sb)->s_nilfs->ns_cpfile;
+	struct nilfs_transaction_info ti;
+	__u64 cno;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (copy_from_user(&cno, argp, sizeof(cno)))
+		return -EFAULT;
+
+	nilfs_transaction_begin(inode->i_sb, &ti, 0);
+	ret = nilfs_cpfile_delete_checkpoint(cpfile, cno);
+	if (unlikely(ret < 0)) {
+		nilfs_transaction_abort(inode->i_sb);
+		return ret;
+	}
+	nilfs_transaction_commit(inode->i_sb); /* never fails */
+	return ret;
+}
+
+static ssize_t
+nilfs_ioctl_do_get_cpinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			  void *buf, size_t size, size_t nmembs)
+{
+	return nilfs_cpfile_get_cpinfo(nilfs->ns_cpfile, posp, flags, buf,
+				       nmembs);
+}
+
+static int nilfs_ioctl_get_cpinfo(struct inode *inode, struct file *filp,
+				  unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_argv argv;
+	int ret;
+
+	if (copy_from_user(&argv, argp, sizeof(argv)))
+		return -EFAULT;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
+				    nilfs_ioctl_do_get_cpinfo);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &argv, sizeof(argv)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static int nilfs_ioctl_get_cpstat(struct inode *inode, struct file *filp,
+				  unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_cpstat cpstat;
+	int ret;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_cpfile_get_stat(nilfs->ns_cpfile, &cpstat);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &cpstat, sizeof(cpstat)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static ssize_t
+nilfs_ioctl_do_get_suinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			  void *buf, size_t size, size_t nmembs)
+{
+	return nilfs_sufile_get_suinfo(nilfs->ns_sufile, *posp, buf, nmembs);
+}
+
+static int nilfs_ioctl_get_suinfo(struct inode *inode, struct file *filp,
+				  unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_argv argv;
+	int ret;
+
+	if (copy_from_user(&argv, argp, sizeof(argv)))
+		return -EFAULT;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
+				    nilfs_ioctl_do_get_suinfo);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &argv, sizeof(argv)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static int nilfs_ioctl_get_sustat(struct inode *inode, struct file *filp,
+				  unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_sustat sustat;
+	int ret;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_sufile_get_stat(nilfs->ns_sufile, &sustat);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &sustat, sizeof(sustat)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static ssize_t
+nilfs_ioctl_do_get_vinfo(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			 void *buf, size_t size, size_t nmembs)
+{
+	return nilfs_dat_get_vinfo(nilfs_dat_inode(nilfs), buf, nmembs);
+}
+
+static int nilfs_ioctl_get_vinfo(struct inode *inode, struct file *filp,
+				 unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_argv argv;
+	int ret;
+
+	if (copy_from_user(&argv, argp, sizeof(argv)))
+		return -EFAULT;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
+				    nilfs_ioctl_do_get_vinfo);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &argv, sizeof(argv)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static ssize_t
+nilfs_ioctl_do_get_bdescs(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			  void *buf, size_t size, size_t nmembs)
+{
+	struct inode *dat = nilfs_dat_inode(nilfs);
+	struct nilfs_bmap *bmap = NILFS_I(dat)->i_bmap;
+	struct nilfs_bdesc *bdescs = buf;
+	int ret, i;
+
+	for (i = 0; i < nmembs; i++) {
+		ret = nilfs_bmap_lookup_at_level(bmap,
+						 bdescs[i].bd_offset,
+						 bdescs[i].bd_level + 1,
+						 &bdescs[i].bd_blocknr);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				return ret;
+			bdescs[i].bd_blocknr = 0;
+		}
+	}
+	return nmembs;
+}
+
+static int nilfs_ioctl_get_bdescs(struct inode *inode, struct file *filp,
+				  unsigned int cmd, void __user *argp)
+{
+	struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+	struct nilfs_argv argv;
+	int ret;
+
+	if (copy_from_user(&argv, argp, sizeof(argv)))
+		return -EFAULT;
+
+	down_read(&nilfs->ns_segctor_sem);
+	ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
+				    nilfs_ioctl_do_get_bdescs);
+	up_read(&nilfs->ns_segctor_sem);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(argp, &argv, sizeof(argv)))
+		ret = -EFAULT;
+	return ret;
+}
+
+static int nilfs_ioctl_move_inode_block(struct inode *inode,
+					struct nilfs_vdesc *vdesc,
+					struct list_head *buffers)
+{
+	struct buffer_head *bh;
+	int ret;
+
+	if (vdesc->vd_flags == 0)
+		ret = nilfs_gccache_submit_read_data(
+			inode, vdesc->vd_offset, vdesc->vd_blocknr,
+			vdesc->vd_vblocknr, &bh);
+	else
+		ret = nilfs_gccache_submit_read_node(
+			inode, vdesc->vd_blocknr, vdesc->vd_vblocknr, &bh);
+
+	if (unlikely(ret < 0)) {
+		if (ret == -ENOENT)
+			printk(KERN_CRIT
+			       "%s: invalid virtual block address (%s): "
+			       "ino=%llu, cno=%llu, offset=%llu, "
+			       "blocknr=%llu, vblocknr=%llu\n",
+			       __func__, vdesc->vd_flags ? "node" : "data",
+			       (unsigned long long)vdesc->vd_ino,
+			       (unsigned long long)vdesc->vd_cno,
+			       (unsigned long long)vdesc->vd_offset,
+			       (unsigned long long)vdesc->vd_blocknr,
+			       (unsigned long long)vdesc->vd_vblocknr);
+		return ret;
+	}
+	bh->b_private = vdesc;
+	list_add_tail(&bh->b_assoc_buffers, buffers);
+	return 0;
+}
+
+static ssize_t
+nilfs_ioctl_do_move_blocks(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			   void *buf, size_t size, size_t nmembs)
+{
+	struct inode *inode;
+	struct nilfs_vdesc *vdesc;
+	struct buffer_head *bh, *n;
+	LIST_HEAD(buffers);
+	ino_t ino;
+	__u64 cno;
+	int i, ret;
+
+	for (i = 0, vdesc = buf; i < nmembs; ) {
+		ino = vdesc->vd_ino;
+		cno = vdesc->vd_cno;
+		inode = nilfs_gc_iget(nilfs, ino, cno);
+		if (unlikely(inode == NULL)) {
+			ret = -ENOMEM;
+			goto failed;
+		}
+		do {
+			ret = nilfs_ioctl_move_inode_block(inode, vdesc,
+							   &buffers);
+			if (unlikely(ret < 0))
+				goto failed;
+			vdesc++;
+		} while (++i < nmembs &&
+			 vdesc->vd_ino == ino && vdesc->vd_cno == cno);
+	}
+
+	list_for_each_entry_safe(bh, n, &buffers, b_assoc_buffers) {
+		ret = nilfs_gccache_wait_and_mark_dirty(bh);
+		if (unlikely(ret < 0)) {
+			if (ret == -EEXIST) {
+				vdesc = bh->b_private;
+				printk(KERN_CRIT
+				       "%s: conflicting %s buffer: "
+				       "ino=%llu, cno=%llu, offset=%llu, "
+				       "blocknr=%llu, vblocknr=%llu\n",
+				       __func__,
+				       vdesc->vd_flags ? "node" : "data",
+				       (unsigned long long)vdesc->vd_ino,
+				       (unsigned long long)vdesc->vd_cno,
+				       (unsigned long long)vdesc->vd_offset,
+				       (unsigned long long)vdesc->vd_blocknr,
+				       (unsigned long long)vdesc->vd_vblocknr);
+			}
+			goto failed;
+		}
+		list_del_init(&bh->b_assoc_buffers);
+		bh->b_private = NULL;
+		brelse(bh);
+	}
+	return nmembs;
+
+ failed:
+	list_for_each_entry_safe(bh, n, &buffers, b_assoc_buffers) {
+		list_del_init(&bh->b_assoc_buffers);
+		bh->b_private = NULL;
+		brelse(bh);
+	}
+	return ret;
+}
+
+static inline int nilfs_ioctl_move_blocks(struct the_nilfs *nilfs,
+					  struct nilfs_argv *argv,
+					  int dir)
+{
+	return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
+				     nilfs_ioctl_do_move_blocks);
+}
+
+static ssize_t
+nilfs_ioctl_do_delete_checkpoints(struct the_nilfs *nilfs, __u64 *posp,
+				  int flags, void *buf, size_t size,
+				  size_t nmembs)
+{
+	struct inode *cpfile = nilfs->ns_cpfile;
+	struct nilfs_period *periods = buf;
+	int ret, i;
+
+	for (i = 0; i < nmembs; i++) {
+		ret = nilfs_cpfile_delete_checkpoints(
+			cpfile, periods[i].p_start, periods[i].p_end);
+		if (ret < 0)
+			return ret;
+	}
+	return nmembs;
+}
+
+static inline int nilfs_ioctl_delete_checkpoints(struct the_nilfs *nilfs,
+						 struct nilfs_argv *argv,
+						 int dir)
+{
+	return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
+				     nilfs_ioctl_do_delete_checkpoints);
+}
+
+static ssize_t
+nilfs_ioctl_do_free_vblocknrs(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			      void *buf, size_t size, size_t nmembs)
+{
+	int ret = nilfs_dat_freev(nilfs_dat_inode(nilfs), buf, nmembs);
+
+	return (ret < 0) ? ret : nmembs;
+}
+
+static inline int nilfs_ioctl_free_vblocknrs(struct the_nilfs *nilfs,
+					     struct nilfs_argv *argv,
+					     int dir)
+{
+	return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
+				     nilfs_ioctl_do_free_vblocknrs);
+}
+
+static ssize_t
+nilfs_ioctl_do_mark_blocks_dirty(struct the_nilfs *nilfs, __u64 *posp,
+				 int flags, void *buf, size_t size,
+				 size_t nmembs)
+{
+	struct inode *dat = nilfs_dat_inode(nilfs);
+	struct nilfs_bmap *bmap = NILFS_I(dat)->i_bmap;
+	struct nilfs_bdesc *bdescs = buf;
+	int ret, i;
+
+	for (i = 0; i < nmembs; i++) {
+		/* XXX: use macro or inline func to check liveness */
+		ret = nilfs_bmap_lookup_at_level(bmap,
+						 bdescs[i].bd_offset,
+						 bdescs[i].bd_level + 1,
+						 &bdescs[i].bd_blocknr);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				return ret;
+			bdescs[i].bd_blocknr = 0;
+		}
+		if (bdescs[i].bd_blocknr != bdescs[i].bd_oblocknr)
+			/* skip dead block */
+			continue;
+		if (bdescs[i].bd_level == 0) {
+			ret = nilfs_mdt_mark_block_dirty(dat,
+							 bdescs[i].bd_offset);
+			if (ret < 0) {
+				WARN_ON(ret == -ENOENT);
+				return ret;
+			}
+		} else {
+			ret = nilfs_bmap_mark(bmap, bdescs[i].bd_offset,
+					      bdescs[i].bd_level);
+			if (ret < 0) {
+				WARN_ON(ret == -ENOENT);
+				return ret;
+			}
+		}
+	}
+	return nmembs;
+}
+
+static inline int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs,
+						struct nilfs_argv *argv,
+						int dir)
+{
+	return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
+				     nilfs_ioctl_do_mark_blocks_dirty);
+}
+
+static ssize_t
+nilfs_ioctl_do_free_segments(struct the_nilfs *nilfs, __u64 *posp, int flags,
+			     void *buf, size_t size, size_t nmembs)
+{
+	struct nilfs_sb_info *sbi = nilfs_get_writer(nilfs);
+	int ret;
+
+	if (unlikely(!sbi))
+		return -EROFS;
+	ret = nilfs_segctor_add_segments_to_be_freed(
+		NILFS_SC(sbi), buf, nmembs);
+	nilfs_put_writer(nilfs);
+
+	return (ret < 0) ? ret : nmembs;
+}
+
+static inline int nilfs_ioctl_free_segments(struct the_nilfs *nilfs,
+					     struct nilfs_argv *argv,
+					     int dir)
+{
+	return nilfs_ioctl_wrap_copy(nilfs, argv, dir,
+				     nilfs_ioctl_do_free_segments);
+}
+
+int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
+				       void __user *argp)
+{
+	struct nilfs_argv argv[5];
+	const char *msg;
+	int dir, ret;
+
+	if (copy_from_user(argv, argp, sizeof(argv)))
+		return -EFAULT;
+
+	dir = _IOC_WRITE;
+	ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], dir);
+	if (ret < 0) {
+		msg = "cannot read source blocks";
+		goto failed;
+	}
+	ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], dir);
+	if (ret < 0) {
+		/*
+		 * can safely abort because checkpoints can be removed
+		 * independently.
+		 */
+		msg = "cannot delete checkpoints";
+		goto failed;
+	}
+	ret = nilfs_ioctl_free_vblocknrs(nilfs, &argv[2], dir);
+	if (ret < 0) {
+		/*
+		 * can safely abort because DAT file is updated atomically
+		 * using a copy-on-write technique.
+		 */
+		msg = "cannot delete virtual blocks from DAT file";
+		goto failed;
+	}
+	ret = nilfs_ioctl_mark_blocks_dirty(nilfs, &argv[3], dir);
+	if (ret < 0) {
+		/*
+		 * can safely abort because the operation is nondestructive.
+		 */
+		msg = "cannot mark copying blocks dirty";
+		goto failed;
+	}
+	ret = nilfs_ioctl_free_segments(nilfs, &argv[4], dir);
+	if (ret < 0) {
+		/*
+		 * can safely abort because this operation is atomic.
+		 */
+		msg = "cannot set segments to be freed";
+		goto failed;
+	}
+	return 0;
+
+ failed:
+	nilfs_remove_all_gcinode(nilfs);
+	printk(KERN_ERR "NILFS: GC failed during preparation: %s: err=%d\n",
+	       msg, ret);
+	return ret;
+}
+
+static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
+				      unsigned int cmd, void __user *argp)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	return nilfs_clean_segments(inode->i_sb, argp);
+}
+
+static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
+			    unsigned int cmd, void __user *argp)
+{
+	__u64 cno;
+	int ret;
+
+	ret = nilfs_construct_segment(inode->i_sb);
+	if (ret < 0)
+		return ret;
+
+	if (argp != NULL) {
+		cno = NILFS_SB(inode->i_sb)->s_nilfs->ns_cno - 1;
+		if (copy_to_user(argp, &cno, sizeof(cno)))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+long nilfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = filp->f_dentry->d_inode;
+	void __user *argp = (void * __user *)arg;
+
+	switch (cmd) {
+	case NILFS_IOCTL_CHANGE_CPMODE:
+		return nilfs_ioctl_change_cpmode(inode, filp, cmd, argp);
+	case NILFS_IOCTL_DELETE_CHECKPOINT:
+		return nilfs_ioctl_delete_checkpoint(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_CPINFO:
+		return nilfs_ioctl_get_cpinfo(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_CPSTAT:
+		return nilfs_ioctl_get_cpstat(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_SUINFO:
+		return nilfs_ioctl_get_suinfo(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_SUSTAT:
+		return nilfs_ioctl_get_sustat(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_VINFO:
+		/* XXX: rename to ??? */
+		return nilfs_ioctl_get_vinfo(inode, filp, cmd, argp);
+	case NILFS_IOCTL_GET_BDESCS:
+		return nilfs_ioctl_get_bdescs(inode, filp, cmd, argp);
+	case NILFS_IOCTL_CLEAN_SEGMENTS:
+		return nilfs_ioctl_clean_segments(inode, filp, cmd, argp);
+	case NILFS_IOCTL_SYNC:
+		return nilfs_ioctl_sync(inode, filp, cmd, argp);
+	default:
+		return -ENOTTY;
+	}
+}
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
new file mode 100644
index 00000000000..47dd815433f
--- /dev/null
+++ b/fs/nilfs2/mdt.c
@@ -0,0 +1,563 @@
+/*
+ * mdt.c - meta data file for NILFS
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/mm.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+#include <linux/swap.h>
+#include "nilfs.h"
+#include "segment.h"
+#include "page.h"
+#include "mdt.h"
+
+
+#define NILFS_MDT_MAX_RA_BLOCKS		(16 - 1)
+
+#define INIT_UNUSED_INODE_FIELDS
+
+static int
+nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
+			   struct buffer_head *bh,
+			   void (*init_block)(struct inode *,
+					      struct buffer_head *, void *))
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	void *kaddr;
+	int ret;
+
+	/* Caller exclude read accesses using page lock */
+
+	/* set_buffer_new(bh); */
+	bh->b_blocknr = 0;
+
+	ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
+	if (unlikely(ret))
+		return ret;
+
+	set_buffer_mapped(bh);
+
+	kaddr = kmap_atomic(bh->b_page, KM_USER0);
+	memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
+	if (init_block)
+		init_block(inode, bh, kaddr);
+	flush_dcache_page(bh->b_page);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	set_buffer_uptodate(bh);
+	nilfs_mark_buffer_dirty(bh);
+	nilfs_mdt_mark_dirty(inode);
+	return 0;
+}
+
+static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
+				  struct buffer_head **out_bh,
+				  void (*init_block)(struct inode *,
+						     struct buffer_head *,
+						     void *))
+{
+	struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
+	struct nilfs_sb_info *writer = NULL;
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_transaction_info ti;
+	struct buffer_head *bh;
+	int err;
+
+	if (!sb) {
+		writer = nilfs_get_writer(nilfs);
+		if (!writer) {
+			err = -EROFS;
+			goto out;
+		}
+		sb = writer->s_super;
+	}
+
+	nilfs_transaction_begin(sb, &ti, 0);
+
+	err = -ENOMEM;
+	bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
+	if (unlikely(!bh))
+		goto failed_unlock;
+
+	err = -EEXIST;
+	if (buffer_uptodate(bh) || buffer_mapped(bh))
+		goto failed_bh;
+#if 0
+	/* The uptodate flag is not protected by the page lock, but
+	   the mapped flag is.  Thus, we don't have to wait the buffer. */
+	wait_on_buffer(bh);
+	if (buffer_uptodate(bh))
+		goto failed_bh;
+#endif
+
+	bh->b_bdev = nilfs->ns_bdev;
+	err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
+	if (likely(!err)) {
+		get_bh(bh);
+		*out_bh = bh;
+	}
+
+ failed_bh:
+	unlock_page(bh->b_page);
+	page_cache_release(bh->b_page);
+	brelse(bh);
+
+ failed_unlock:
+	if (likely(!err))
+		err = nilfs_transaction_commit(sb);
+	else
+		nilfs_transaction_abort(sb);
+	if (writer)
+		nilfs_put_writer(nilfs);
+ out:
+	return err;
+}
+
+static int
+nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
+		       int mode, struct buffer_head **out_bh)
+{
+	struct buffer_head *bh;
+	unsigned long blknum = 0;
+	int ret = -ENOMEM;
+
+	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
+	if (unlikely(!bh))
+		goto failed;
+
+	ret = -EEXIST; /* internal code */
+	if (buffer_uptodate(bh))
+		goto out;
+
+	if (mode == READA) {
+		if (!trylock_buffer(bh)) {
+			ret = -EBUSY;
+			goto failed_bh;
+		}
+	} else /* mode == READ */
+		lock_buffer(bh);
+
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		goto out;
+	}
+	if (!buffer_mapped(bh)) { /* unused buffer */
+		ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff,
+					&blknum);
+		if (unlikely(ret)) {
+			unlock_buffer(bh);
+			goto failed_bh;
+		}
+		bh->b_bdev = NILFS_MDT(inode)->mi_nilfs->ns_bdev;
+		bh->b_blocknr = blknum;
+		set_buffer_mapped(bh);
+	}
+
+	bh->b_end_io = end_buffer_read_sync;
+	get_bh(bh);
+	submit_bh(mode, bh);
+	ret = 0;
+ out:
+	get_bh(bh);
+	*out_bh = bh;
+
+ failed_bh:
+	unlock_page(bh->b_page);
+	page_cache_release(bh->b_page);
+	brelse(bh);
+ failed:
+	return ret;
+}
+
+static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
+				struct buffer_head **out_bh)
+{
+	struct buffer_head *first_bh, *bh;
+	unsigned long blkoff;
+	int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
+	int err;
+
+	err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
+	if (err == -EEXIST) /* internal code */
+		goto out;
+
+	if (unlikely(err))
+		goto failed;
+
+	blkoff = block + 1;
+	for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
+		err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
+		if (likely(!err || err == -EEXIST))
+			brelse(bh);
+		else if (err != -EBUSY)
+			break; /* abort readahead if bmap lookup failed */
+
+		if (!buffer_locked(first_bh))
+			goto out_no_wait;
+	}
+
+	wait_on_buffer(first_bh);
+
+ out_no_wait:
+	err = -EIO;
+	if (!buffer_uptodate(first_bh))
+		goto failed_bh;
+ out:
+	*out_bh = first_bh;
+	return 0;
+
+ failed_bh:
+	brelse(first_bh);
+ failed:
+	return err;
+}
+
+/**
+ * nilfs_mdt_get_block - read or create a buffer on meta data file.
+ * @inode: inode of the meta data file
+ * @blkoff: block offset
+ * @create: create flag
+ * @init_block: initializer used for newly allocated block
+ * @out_bh: output of a pointer to the buffer_head
+ *
+ * nilfs_mdt_get_block() looks up the specified buffer and tries to create
+ * a new buffer if @create is not zero.  On success, the returned buffer is
+ * assured to be either existing or formatted using a buffer lock on success.
+ * @out_bh is substituted only when zero is returned.
+ *
+ * Return Value: On success, it returns 0. On error, the following negative
+ * error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOENT - the specified block does not exist (hole block)
+ *
+ * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
+ *
+ * %-EROFS - Read only filesystem (for create mode)
+ */
+int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
+			void (*init_block)(struct inode *,
+					   struct buffer_head *, void *),
+			struct buffer_head **out_bh)
+{
+	int ret;
+
+	/* Should be rewritten with merging nilfs_mdt_read_block() */
+ retry:
+	ret = nilfs_mdt_read_block(inode, blkoff, out_bh);
+	if (!create || ret != -ENOENT)
+		return ret;
+
+	ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
+	if (unlikely(ret == -EEXIST)) {
+		/* create = 0; */  /* limit read-create loop retries */
+		goto retry;
+	}
+	return ret;
+}
+
+/**
+ * nilfs_mdt_delete_block - make a hole on the meta data file.
+ * @inode: inode of the meta data file
+ * @block: block offset
+ *
+ * Return Value: On success, zero is returned.
+ * On error, one of the following negative error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-EIO - I/O error
+ *
+ * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
+ */
+int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	int err;
+
+	err = nilfs_bmap_delete(ii->i_bmap, block);
+	if (likely(!err)) {
+		nilfs_mdt_mark_dirty(inode);
+		nilfs_mdt_forget_block(inode, block);
+	}
+	return err;
+}
+
+/**
+ * nilfs_mdt_forget_block - discard dirty state and try to remove the page
+ * @inode: inode of the meta data file
+ * @block: block offset
+ *
+ * nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
+ * tries to release the page including the buffer from a page cache.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error code is returned.
+ *
+ * %-EBUSY - page has an active buffer.
+ *
+ * %-ENOENT - page cache has no page addressed by the offset.
+ */
+int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
+{
+	pgoff_t index = (pgoff_t)block >>
+		(PAGE_CACHE_SHIFT - inode->i_blkbits);
+	struct page *page;
+	unsigned long first_block;
+	int ret = 0;
+	int still_dirty;
+
+	page = find_lock_page(inode->i_mapping, index);
+	if (!page)
+		return -ENOENT;
+
+	wait_on_page_writeback(page);
+
+	first_block = (unsigned long)index <<
+		(PAGE_CACHE_SHIFT - inode->i_blkbits);
+	if (page_has_buffers(page)) {
+		struct buffer_head *bh;
+
+		bh = nilfs_page_get_nth_block(page, block - first_block);
+		nilfs_forget_buffer(bh);
+	}
+	still_dirty = PageDirty(page);
+	unlock_page(page);
+	page_cache_release(page);
+
+	if (still_dirty ||
+	    invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
+		ret = -EBUSY;
+	return ret;
+}
+
+/**
+ * nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
+ * @inode: inode of the meta data file
+ * @block: block offset
+ *
+ * Return Value: On success, it returns 0. On error, the following negative
+ * error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOENT - the specified block does not exist (hole block)
+ *
+ * %-EINVAL - bmap is broken. (the caller should call nilfs_error())
+ */
+int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
+{
+	struct buffer_head *bh;
+	int err;
+
+	err = nilfs_mdt_read_block(inode, block, &bh);
+	if (unlikely(err))
+		return err;
+	nilfs_mark_buffer_dirty(bh);
+	nilfs_mdt_mark_dirty(inode);
+	brelse(bh);
+	return 0;
+}
+
+int nilfs_mdt_fetch_dirty(struct inode *inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
+		set_bit(NILFS_I_DIRTY, &ii->i_state);
+		return 1;
+	}
+	return test_bit(NILFS_I_DIRTY, &ii->i_state);
+}
+
+static int
+nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
+{
+	struct inode *inode = container_of(page->mapping,
+					   struct inode, i_data);
+	struct super_block *sb = inode->i_sb;
+	struct nilfs_sb_info *writer = NULL;
+	int err = 0;
+
+	redirty_page_for_writepage(wbc, page);
+	unlock_page(page);
+
+	if (page->mapping->assoc_mapping)
+		return 0; /* Do not request flush for shadow page cache */
+	if (!sb) {
+		writer = nilfs_get_writer(NILFS_MDT(inode)->mi_nilfs);
+		if (!writer)
+			return -EROFS;
+		sb = writer->s_super;
+	}
+
+	if (wbc->sync_mode == WB_SYNC_ALL)
+		err = nilfs_construct_segment(sb);
+	else if (wbc->for_reclaim)
+		nilfs_flush_segment(sb, inode->i_ino);
+
+	if (writer)
+		nilfs_put_writer(NILFS_MDT(inode)->mi_nilfs);
+	return err;
+}
+
+
+static struct address_space_operations def_mdt_aops = {
+	.writepage		= nilfs_mdt_write_page,
+};
+
+static struct inode_operations def_mdt_iops;
+static struct file_operations def_mdt_fops;
+
+/*
+ * NILFS2 uses pseudo inodes for meta data files such as DAT, cpfile, sufile,
+ * ifile, or gcinodes.  This allows the B-tree code and segment constructor
+ * to treat them like regular files, and this helps to simplify the
+ * implementation.
+ *   On the other hand, some of the pseudo inodes have an irregular point:
+ * They don't have valid inode->i_sb pointer because their lifetimes are
+ * longer than those of the super block structs; they may continue for
+ * several consecutive mounts/umounts.  This would need discussions.
+ */
+struct inode *
+nilfs_mdt_new_common(struct the_nilfs *nilfs, struct super_block *sb,
+		     ino_t ino, gfp_t gfp_mask)
+{
+	struct inode *inode = nilfs_alloc_inode(sb);
+
+	if (!inode)
+		return NULL;
+	else {
+		struct address_space * const mapping = &inode->i_data;
+		struct nilfs_mdt_info *mi = kzalloc(sizeof(*mi), GFP_NOFS);
+
+		if (!mi) {
+			nilfs_destroy_inode(inode);
+			return NULL;
+		}
+		mi->mi_nilfs = nilfs;
+		init_rwsem(&mi->mi_sem);
+
+		inode->i_sb = sb; /* sb may be NULL for some meta data files */
+		inode->i_blkbits = nilfs->ns_blocksize_bits;
+		inode->i_flags = 0;
+		atomic_set(&inode->i_count, 1);
+		inode->i_nlink = 1;
+		inode->i_ino = ino;
+		inode->i_mode = S_IFREG;
+		inode->i_private = mi;
+
+#ifdef INIT_UNUSED_INODE_FIELDS
+		atomic_set(&inode->i_writecount, 0);
+		inode->i_size = 0;
+		inode->i_blocks = 0;
+		inode->i_bytes = 0;
+		inode->i_generation = 0;
+#ifdef CONFIG_QUOTA
+		memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
+#endif
+		inode->i_pipe = NULL;
+		inode->i_bdev = NULL;
+		inode->i_cdev = NULL;
+		inode->i_rdev = 0;
+#ifdef CONFIG_SECURITY
+		inode->i_security = NULL;
+#endif
+		inode->dirtied_when = 0;
+
+		INIT_LIST_HEAD(&inode->i_list);
+		INIT_LIST_HEAD(&inode->i_sb_list);
+		inode->i_state = 0;
+#endif
+
+		spin_lock_init(&inode->i_lock);
+		mutex_init(&inode->i_mutex);
+		init_rwsem(&inode->i_alloc_sem);
+
+		mapping->host = NULL;  /* instead of inode */
+		mapping->flags = 0;
+		mapping_set_gfp_mask(mapping, gfp_mask);
+		mapping->assoc_mapping = NULL;
+		mapping->backing_dev_info = nilfs->ns_bdi;
+
+		inode->i_mapping = mapping;
+	}
+
+	return inode;
+}
+
+struct inode *nilfs_mdt_new(struct the_nilfs *nilfs, struct super_block *sb,
+			    ino_t ino, gfp_t gfp_mask)
+{
+	struct inode *inode = nilfs_mdt_new_common(nilfs, sb, ino, gfp_mask);
+
+	if (!inode)
+		return NULL;
+
+	inode->i_op = &def_mdt_iops;
+	inode->i_fop = &def_mdt_fops;
+	inode->i_mapping->a_ops = &def_mdt_aops;
+	return inode;
+}
+
+void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
+			      unsigned header_size)
+{
+	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+
+	mi->mi_entry_size = entry_size;
+	mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
+	mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
+}
+
+void nilfs_mdt_set_shadow(struct inode *orig, struct inode *shadow)
+{
+	shadow->i_mapping->assoc_mapping = orig->i_mapping;
+	NILFS_I(shadow)->i_btnode_cache.assoc_mapping =
+		&NILFS_I(orig)->i_btnode_cache;
+}
+
+void nilfs_mdt_clear(struct inode *inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+	invalidate_mapping_pages(inode->i_mapping, 0, -1);
+	truncate_inode_pages(inode->i_mapping, 0);
+
+	nilfs_bmap_clear(ii->i_bmap);
+	nilfs_btnode_cache_clear(&ii->i_btnode_cache);
+}
+
+void nilfs_mdt_destroy(struct inode *inode)
+{
+	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
+
+	kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
+	kfree(mdi);
+	nilfs_destroy_inode(inode);
+}
diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
new file mode 100644
index 00000000000..df683e0bca6
--- /dev/null
+++ b/fs/nilfs2/mdt.h
@@ -0,0 +1,125 @@
+/*
+ * mdt.h - NILFS meta data file prototype and definitions
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#ifndef _NILFS_MDT_H
+#define _NILFS_MDT_H
+
+#include <linux/buffer_head.h>
+#include <linux/blockgroup_lock.h>
+#include "nilfs.h"
+#include "page.h"
+
+/**
+ * struct nilfs_mdt_info - on-memory private data of meta data files
+ * @mi_nilfs: back pointer to the_nilfs struct
+ * @mi_sem: reader/writer semaphore for meta data operations
+ * @mi_bgl: per-blockgroup locking
+ * @mi_entry_size: size of an entry
+ * @mi_first_entry_offset: offset to the first entry
+ * @mi_entries_per_block: number of entries in a block
+ * @mi_blocks_per_group: number of blocks in a group
+ * @mi_blocks_per_desc_block: number of blocks per descriptor block
+ */
+struct nilfs_mdt_info {
+	struct the_nilfs       *mi_nilfs;
+	struct rw_semaphore	mi_sem;
+	struct blockgroup_lock *mi_bgl;
+	unsigned		mi_entry_size;
+	unsigned		mi_first_entry_offset;
+	unsigned long		mi_entries_per_block;
+	unsigned long		mi_blocks_per_group;
+	unsigned long		mi_blocks_per_desc_block;
+};
+
+static inline struct nilfs_mdt_info *NILFS_MDT(const struct inode *inode)
+{
+	return inode->i_private;
+}
+
+static inline struct the_nilfs *NILFS_I_NILFS(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+
+	return sb ? NILFS_SB(sb)->s_nilfs : NILFS_MDT(inode)->mi_nilfs;
+}
+
+/* Default GFP flags using highmem */
+#define NILFS_MDT_GFP      (__GFP_WAIT | __GFP_IO | __GFP_HIGHMEM)
+
+int nilfs_mdt_get_block(struct inode *, unsigned long, int,
+			void (*init_block)(struct inode *,
+					   struct buffer_head *, void *),
+			struct buffer_head **);
+int nilfs_mdt_delete_block(struct inode *, unsigned long);
+int nilfs_mdt_forget_block(struct inode *, unsigned long);
+int nilfs_mdt_mark_block_dirty(struct inode *, unsigned long);
+int nilfs_mdt_fetch_dirty(struct inode *);
+
+struct inode *nilfs_mdt_new(struct the_nilfs *, struct super_block *, ino_t,
+			    gfp_t);
+struct inode *nilfs_mdt_new_common(struct the_nilfs *, struct super_block *,
+				   ino_t, gfp_t);
+void nilfs_mdt_destroy(struct inode *);
+void nilfs_mdt_clear(struct inode *);
+void nilfs_mdt_set_entry_size(struct inode *, unsigned, unsigned);
+void nilfs_mdt_set_shadow(struct inode *, struct inode *);
+
+
+#define nilfs_mdt_mark_buffer_dirty(bh)	nilfs_mark_buffer_dirty(bh)
+
+static inline void nilfs_mdt_mark_dirty(struct inode *inode)
+{
+	if (!test_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state))
+		set_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
+}
+
+static inline void nilfs_mdt_clear_dirty(struct inode *inode)
+{
+	clear_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
+}
+
+static inline __u64 nilfs_mdt_cno(struct inode *inode)
+{
+	return NILFS_MDT(inode)->mi_nilfs->ns_cno;
+}
+
+#define nilfs_mdt_bgl_lock(inode, bg) \
+	(&NILFS_MDT(inode)->mi_bgl->locks[(bg) & (NR_BG_LOCKS-1)].lock)
+
+
+static inline int
+nilfs_mdt_read_inode_direct(struct inode *inode, struct buffer_head *bh,
+			    unsigned n)
+{
+	return nilfs_read_inode_common(
+		inode, (struct nilfs_inode *)(bh->b_data + n));
+}
+
+static inline void
+nilfs_mdt_write_inode_direct(struct inode *inode, struct buffer_head *bh,
+			     unsigned n)
+{
+	nilfs_write_inode_common(
+		inode, (struct nilfs_inode *)(bh->b_data + n), 1);
+}
+
+#endif /* _NILFS_MDT_H */
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
new file mode 100644
index 00000000000..df70dadb336
--- /dev/null
+++ b/fs/nilfs2/namei.c
@@ -0,0 +1,474 @@
+/*
+ * namei.c - NILFS pathname lookup operations.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>,
+ *                       Ryusuke Konishi <ryusuke@osrg.net>
+ */
+/*
+ *  linux/fs/ext2/namei.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/namei.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/pagemap.h>
+#include "nilfs.h"
+
+
+static inline int nilfs_add_nondir(struct dentry *dentry, struct inode *inode)
+{
+	int err = nilfs_add_link(dentry, inode);
+	if (!err) {
+		d_instantiate(dentry, inode);
+		return 0;
+	}
+	inode_dec_link_count(inode);
+	iput(inode);
+	return err;
+}
+
+/*
+ * Methods themselves.
+ */
+
+static struct dentry *
+nilfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+{
+	struct inode *inode;
+	ino_t ino;
+
+	if (dentry->d_name.len > NILFS_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	ino = nilfs_inode_by_name(dir, dentry);
+	inode = NULL;
+	if (ino) {
+		inode = nilfs_iget(dir->i_sb, ino);
+		if (IS_ERR(inode))
+			return ERR_CAST(inode);
+	}
+	return d_splice_alias(inode, dentry);
+}
+
+struct dentry *nilfs_get_parent(struct dentry *child)
+{
+	unsigned long ino;
+	struct inode *inode;
+	struct dentry dotdot;
+
+	dotdot.d_name.name = "..";
+	dotdot.d_name.len = 2;
+
+	ino = nilfs_inode_by_name(child->d_inode, &dotdot);
+	if (!ino)
+		return ERR_PTR(-ENOENT);
+
+	inode = nilfs_iget(child->d_inode->i_sb, ino);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+	return d_obtain_alias(inode);
+}
+
+/*
+ * By the time this is called, we already have created
+ * the directory cache entry for the new file, but it
+ * is so far negative - it has no inode.
+ *
+ * If the create succeeds, we fill in the inode information
+ * with d_instantiate().
+ */
+static int nilfs_create(struct inode *dir, struct dentry *dentry, int mode,
+			struct nameidata *nd)
+{
+	struct inode *inode;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
+	if (err)
+		return err;
+	inode = nilfs_new_inode(dir, mode);
+	err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+		inode->i_op = &nilfs_file_inode_operations;
+		inode->i_fop = &nilfs_file_operations;
+		inode->i_mapping->a_ops = &nilfs_aops;
+		mark_inode_dirty(inode);
+		err = nilfs_add_nondir(dentry, inode);
+	}
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+}
+
+static int
+nilfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
+{
+	struct inode *inode;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	if (!new_valid_dev(rdev))
+		return -EINVAL;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
+	if (err)
+		return err;
+	inode = nilfs_new_inode(dir, mode);
+	err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+		init_special_inode(inode, inode->i_mode, rdev);
+		mark_inode_dirty(inode);
+		err = nilfs_add_nondir(dentry, inode);
+	}
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+}
+
+static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
+			 const char *symname)
+{
+	struct nilfs_transaction_info ti;
+	struct super_block *sb = dir->i_sb;
+	unsigned l = strlen(symname)+1;
+	struct inode *inode;
+	int err;
+
+	if (l > sb->s_blocksize)
+		return -ENAMETOOLONG;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
+	if (err)
+		return err;
+
+	inode = nilfs_new_inode(dir, S_IFLNK | S_IRWXUGO);
+	err = PTR_ERR(inode);
+	if (IS_ERR(inode))
+		goto out;
+
+	/* slow symlink */
+	inode->i_op = &nilfs_symlink_inode_operations;
+	inode->i_mapping->a_ops = &nilfs_aops;
+	err = page_symlink(inode, symname, l);
+	if (err)
+		goto out_fail;
+
+	/* mark_inode_dirty(inode); */
+	/* nilfs_new_inode() and page_symlink() do this */
+
+	err = nilfs_add_nondir(dentry, inode);
+out:
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+
+out_fail:
+	inode_dec_link_count(inode);
+	iput(inode);
+	goto out;
+}
+
+static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
+		      struct dentry *dentry)
+{
+	struct inode *inode = old_dentry->d_inode;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	if (inode->i_nlink >= NILFS_LINK_MAX)
+		return -EMLINK;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
+	if (err)
+		return err;
+
+	inode->i_ctime = CURRENT_TIME;
+	inode_inc_link_count(inode);
+	atomic_inc(&inode->i_count);
+
+	err = nilfs_add_nondir(dentry, inode);
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+}
+
+static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	struct inode *inode;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	if (dir->i_nlink >= NILFS_LINK_MAX)
+		return -EMLINK;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
+	if (err)
+		return err;
+
+	inode_inc_link_count(dir);
+
+	inode = nilfs_new_inode(dir, S_IFDIR | mode);
+	err = PTR_ERR(inode);
+	if (IS_ERR(inode))
+		goto out_dir;
+
+	inode->i_op = &nilfs_dir_inode_operations;
+	inode->i_fop = &nilfs_dir_operations;
+	inode->i_mapping->a_ops = &nilfs_aops;
+
+	inode_inc_link_count(inode);
+
+	err = nilfs_make_empty(inode, dir);
+	if (err)
+		goto out_fail;
+
+	err = nilfs_add_link(dentry, inode);
+	if (err)
+		goto out_fail;
+
+	d_instantiate(dentry, inode);
+out:
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+
+out_fail:
+	inode_dec_link_count(inode);
+	inode_dec_link_count(inode);
+	iput(inode);
+out_dir:
+	inode_dec_link_count(dir);
+	goto out;
+}
+
+static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode;
+	struct nilfs_dir_entry *de;
+	struct page *page;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
+	if (err)
+		return err;
+
+	err = -ENOENT;
+	de = nilfs_find_entry(dir, dentry, &page);
+	if (!de)
+		goto out;
+
+	inode = dentry->d_inode;
+	err = -EIO;
+	if (le64_to_cpu(de->inode) != inode->i_ino)
+		goto out;
+
+	if (!inode->i_nlink) {
+		nilfs_warning(inode->i_sb, __func__,
+			      "deleting nonexistent file (%lu), %d\n",
+			      inode->i_ino, inode->i_nlink);
+		inode->i_nlink = 1;
+	}
+	err = nilfs_delete_entry(de, page);
+	if (err)
+		goto out;
+
+	inode->i_ctime = dir->i_ctime;
+	inode_dec_link_count(inode);
+	err = 0;
+out:
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+}
+
+static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
+	if (err)
+		return err;
+
+	err = -ENOTEMPTY;
+	if (nilfs_empty_dir(inode)) {
+		err = nilfs_unlink(dir, dentry);
+		if (!err) {
+			inode->i_size = 0;
+			inode_dec_link_count(inode);
+			inode_dec_link_count(dir);
+		}
+	}
+	if (!err)
+		err = nilfs_transaction_commit(dir->i_sb);
+	else
+		nilfs_transaction_abort(dir->i_sb);
+
+	return err;
+}
+
+static int nilfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir,	struct dentry *new_dentry)
+{
+	struct inode *old_inode = old_dentry->d_inode;
+	struct inode *new_inode = new_dentry->d_inode;
+	struct page *dir_page = NULL;
+	struct nilfs_dir_entry *dir_de = NULL;
+	struct page *old_page;
+	struct nilfs_dir_entry *old_de;
+	struct nilfs_transaction_info ti;
+	int err;
+
+	err = nilfs_transaction_begin(old_dir->i_sb, &ti, 1);
+	if (unlikely(err))
+		return err;
+
+	err = -ENOENT;
+	old_de = nilfs_find_entry(old_dir, old_dentry, &old_page);
+	if (!old_de)
+		goto out;
+
+	if (S_ISDIR(old_inode->i_mode)) {
+		err = -EIO;
+		dir_de = nilfs_dotdot(old_inode, &dir_page);
+		if (!dir_de)
+			goto out_old;
+	}
+
+	if (new_inode) {
+		struct page *new_page;
+		struct nilfs_dir_entry *new_de;
+
+		err = -ENOTEMPTY;
+		if (dir_de && !nilfs_empty_dir(new_inode))
+			goto out_dir;
+
+		err = -ENOENT;
+		new_de = nilfs_find_entry(new_dir, new_dentry, &new_page);
+		if (!new_de)
+			goto out_dir;
+		inode_inc_link_count(old_inode);
+		nilfs_set_link(new_dir, new_de, new_page, old_inode);
+		new_inode->i_ctime = CURRENT_TIME;
+		if (dir_de)
+			drop_nlink(new_inode);
+		inode_dec_link_count(new_inode);
+	} else {
+		if (dir_de) {
+			err = -EMLINK;
+			if (new_dir->i_nlink >= NILFS_LINK_MAX)
+				goto out_dir;
+		}
+		inode_inc_link_count(old_inode);
+		err = nilfs_add_link(new_dentry, old_inode);
+		if (err) {
+			inode_dec_link_count(old_inode);
+			goto out_dir;
+		}
+		if (dir_de)
+			inode_inc_link_count(new_dir);
+	}
+
+	/*
+	 * Like most other Unix systems, set the ctime for inodes on a
+	 * rename.
+	 * inode_dec_link_count() will mark the inode dirty.
+	 */
+	old_inode->i_ctime = CURRENT_TIME;
+
+	nilfs_delete_entry(old_de, old_page);
+	inode_dec_link_count(old_inode);
+
+	if (dir_de) {
+		nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
+		inode_dec_link_count(old_dir);
+	}
+
+	err = nilfs_transaction_commit(old_dir->i_sb);
+	return err;
+
+out_dir:
+	if (dir_de) {
+		kunmap(dir_page);
+		page_cache_release(dir_page);
+	}
+out_old:
+	kunmap(old_page);
+	page_cache_release(old_page);
+out:
+	nilfs_transaction_abort(old_dir->i_sb);
+	return err;
+}
+
+struct inode_operations nilfs_dir_inode_operations = {
+	.create		= nilfs_create,
+	.lookup		= nilfs_lookup,
+	.link		= nilfs_link,
+	.unlink		= nilfs_unlink,
+	.symlink	= nilfs_symlink,
+	.mkdir		= nilfs_mkdir,
+	.rmdir		= nilfs_rmdir,
+	.mknod		= nilfs_mknod,
+	.rename		= nilfs_rename,
+	.setattr	= nilfs_setattr,
+	.permission	= nilfs_permission,
+};
+
+struct inode_operations nilfs_special_inode_operations = {
+	.setattr	= nilfs_setattr,
+	.permission	= nilfs_permission,
+};
+
+struct inode_operations nilfs_symlink_inode_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= page_follow_link_light,
+	.put_link	= page_put_link,
+};
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
new file mode 100644
index 00000000000..7558c977db0
--- /dev/null
+++ b/fs/nilfs2/nilfs.h
@@ -0,0 +1,318 @@
+/*
+ * nilfs.h - NILFS local header file.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>
+ *            Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#ifndef _NILFS_H
+#define _NILFS_H
+
+#include <linux/kernel.h>
+#include <linux/buffer_head.h>
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/nilfs2_fs.h>
+#include "the_nilfs.h"
+#include "sb.h"
+#include "bmap.h"
+#include "bmap_union.h"
+
+/*
+ * NILFS filesystem version
+ */
+#define NILFS_VERSION		"2.0.5"
+
+/*
+ * nilfs inode data in memory
+ */
+struct nilfs_inode_info {
+	__u32 i_flags;
+	unsigned long  i_state;		/* Dynamic state flags */
+	struct nilfs_bmap *i_bmap;
+	union nilfs_bmap_union i_bmap_union;
+	__u64 i_xattr;	/* sector_t ??? */
+	__u32 i_dir_start_lookup;
+	__u64 i_cno;		/* check point number for GC inode */
+	struct address_space i_btnode_cache;
+	struct list_head i_dirty;	/* List for connecting dirty files */
+
+#ifdef CONFIG_NILFS_XATTR
+	/*
+	 * Extended attributes can be read independently of the main file
+	 * data. Taking i_sem even when reading would cause contention
+	 * between readers of EAs and writers of regular file data, so
+	 * instead we synchronize on xattr_sem when reading or changing
+	 * EAs.
+	 */
+	struct rw_semaphore xattr_sem;
+#endif
+#ifdef CONFIG_NILFS_POSIX_ACL
+	struct posix_acl *i_acl;
+	struct posix_acl *i_default_acl;
+#endif
+	struct buffer_head *i_bh;	/* i_bh contains a new or dirty
+					   disk inode */
+	struct inode vfs_inode;
+};
+
+static inline struct nilfs_inode_info *NILFS_I(const struct inode *inode)
+{
+	return container_of(inode, struct nilfs_inode_info, vfs_inode);
+}
+
+static inline struct nilfs_inode_info *
+NILFS_BMAP_I(const struct nilfs_bmap *bmap)
+{
+	return container_of((union nilfs_bmap_union *)bmap,
+			    struct nilfs_inode_info,
+			    i_bmap_union);
+}
+
+static inline struct inode *NILFS_BTNC_I(struct address_space *btnc)
+{
+	struct nilfs_inode_info *ii =
+		container_of(btnc, struct nilfs_inode_info, i_btnode_cache);
+	return &ii->vfs_inode;
+}
+
+static inline struct inode *NILFS_AS_I(struct address_space *mapping)
+{
+	return (mapping->host) ? :
+		container_of(mapping, struct inode, i_data);
+}
+
+/*
+ * Dynamic state flags of NILFS on-memory inode (i_state)
+ */
+enum {
+	NILFS_I_NEW = 0,		/* Inode is newly created */
+	NILFS_I_DIRTY,			/* The file is dirty */
+	NILFS_I_QUEUED,			/* inode is in dirty_files list */
+	NILFS_I_BUSY,			/* inode is grabbed by a segment
+					   constructor */
+	NILFS_I_COLLECTED,		/* All dirty blocks are collected */
+	NILFS_I_UPDATED,		/* The file has been written back */
+	NILFS_I_INODE_DIRTY,		/* write_inode is requested */
+	NILFS_I_BMAP,			/* has bmap and btnode_cache */
+	NILFS_I_GCINODE,		/* inode for GC, on memory only */
+	NILFS_I_GCDAT,			/* shadow DAT, on memory only */
+};
+
+/*
+ * Macros to check inode numbers
+ */
+#define NILFS_MDT_INO_BITS   \
+  ((unsigned int)(1 << NILFS_DAT_INO | 1 << NILFS_CPFILE_INO |		\
+		  1 << NILFS_SUFILE_INO | 1 << NILFS_IFILE_INO |	\
+		  1 << NILFS_ATIME_INO | 1 << NILFS_SKETCH_INO))
+
+#define NILFS_SYS_INO_BITS   \
+  ((unsigned int)(1 << NILFS_ROOT_INO) | NILFS_MDT_INO_BITS)
+
+#define NILFS_FIRST_INO(sb)  (NILFS_SB(sb)->s_nilfs->ns_first_ino)
+
+#define NILFS_MDT_INODE(sb, ino) \
+  ((ino) < NILFS_FIRST_INO(sb) && (NILFS_MDT_INO_BITS & (1 << (ino))))
+#define NILFS_VALID_INODE(sb, ino) \
+  ((ino) >= NILFS_FIRST_INO(sb) || (NILFS_SYS_INO_BITS & (1 << (ino))))
+
+/**
+ * struct nilfs_transaction_info: context information for synchronization
+ * @ti_magic: Magic number
+ * @ti_save: Backup of journal_info field of task_struct
+ * @ti_flags: Flags
+ * @ti_count: Nest level
+ * @ti_garbage:	List of inode to be put when releasing semaphore
+ */
+struct nilfs_transaction_info {
+	u32			ti_magic;
+	void		       *ti_save;
+				/* This should never used. If this happens,
+				   one of other filesystems has a bug. */
+	unsigned short		ti_flags;
+	unsigned short		ti_count;
+	struct list_head	ti_garbage;
+};
+
+/* ti_magic */
+#define NILFS_TI_MAGIC		0xd9e392fb
+
+/* ti_flags */
+#define NILFS_TI_DYNAMIC_ALLOC	0x0001  /* Allocated from slab */
+#define NILFS_TI_SYNC		0x0002	/* Force to construct segment at the
+					   end of transaction. */
+#define NILFS_TI_GC		0x0004	/* GC context */
+#define NILFS_TI_COMMIT		0x0008	/* Change happened or not */
+#define NILFS_TI_WRITER		0x0010	/* Constructor context */
+
+
+int nilfs_transaction_begin(struct super_block *,
+			    struct nilfs_transaction_info *, int);
+int nilfs_transaction_commit(struct super_block *);
+void nilfs_transaction_abort(struct super_block *);
+
+static inline void nilfs_set_transaction_flag(unsigned int flag)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+
+	ti->ti_flags |= flag;
+}
+
+static inline int nilfs_test_transaction_flag(unsigned int flag)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+
+	if (ti == NULL || ti->ti_magic != NILFS_TI_MAGIC)
+		return 0;
+	return !!(ti->ti_flags & flag);
+}
+
+static inline int nilfs_doing_gc(void)
+{
+	return nilfs_test_transaction_flag(NILFS_TI_GC);
+}
+
+static inline int nilfs_doing_construction(void)
+{
+	return nilfs_test_transaction_flag(NILFS_TI_WRITER);
+}
+
+static inline struct inode *nilfs_dat_inode(const struct the_nilfs *nilfs)
+{
+	return nilfs_doing_gc() ? nilfs->ns_gc_dat : nilfs->ns_dat;
+}
+
+/*
+ * function prototype
+ */
+#ifdef CONFIG_NILFS_POSIX_ACL
+#error "NILFS: not yet supported POSIX ACL"
+extern int nilfs_permission(struct inode *, int, struct nameidata *);
+extern int nilfs_acl_chmod(struct inode *);
+extern int nilfs_init_acl(struct inode *, struct inode *);
+#else
+#define nilfs_permission   NULL
+
+static inline int nilfs_acl_chmod(struct inode *inode)
+{
+	return 0;
+}
+
+static inline int nilfs_init_acl(struct inode *inode, struct inode *dir)
+{
+	inode->i_mode &= ~current_umask();
+	return 0;
+}
+#endif
+
+#define NILFS_ATIME_DISABLE
+
+/* dir.c */
+extern int nilfs_add_link(struct dentry *, struct inode *);
+extern ino_t nilfs_inode_by_name(struct inode *, struct dentry *);
+extern int nilfs_make_empty(struct inode *, struct inode *);
+extern struct nilfs_dir_entry *
+nilfs_find_entry(struct inode *, struct dentry *, struct page **);
+extern int nilfs_delete_entry(struct nilfs_dir_entry *, struct page *);
+extern int nilfs_empty_dir(struct inode *);
+extern struct nilfs_dir_entry *nilfs_dotdot(struct inode *, struct page **);
+extern void nilfs_set_link(struct inode *, struct nilfs_dir_entry *,
+			   struct page *, struct inode *);
+
+/* file.c */
+extern int nilfs_sync_file(struct file *, struct dentry *, int);
+
+/* ioctl.c */
+long nilfs_ioctl(struct file *, unsigned int, unsigned long);
+int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, void __user *);
+
+/* inode.c */
+extern struct inode *nilfs_new_inode(struct inode *, int);
+extern void nilfs_free_inode(struct inode *);
+extern int nilfs_get_block(struct inode *, sector_t, struct buffer_head *, int);
+extern void nilfs_set_inode_flags(struct inode *);
+extern int nilfs_read_inode_common(struct inode *, struct nilfs_inode *);
+extern void nilfs_write_inode_common(struct inode *, struct nilfs_inode *, int);
+extern struct inode *nilfs_iget(struct super_block *, unsigned long);
+extern void nilfs_update_inode(struct inode *, struct buffer_head *);
+extern void nilfs_truncate(struct inode *);
+extern void nilfs_delete_inode(struct inode *);
+extern int nilfs_setattr(struct dentry *, struct iattr *);
+extern int nilfs_load_inode_block(struct nilfs_sb_info *, struct inode *,
+				  struct buffer_head **);
+extern int nilfs_inode_dirty(struct inode *);
+extern int nilfs_set_file_dirty(struct nilfs_sb_info *, struct inode *,
+				unsigned);
+extern int nilfs_mark_inode_dirty(struct inode *);
+extern void nilfs_dirty_inode(struct inode *);
+
+/* namei.c */
+extern struct dentry *nilfs_get_parent(struct dentry *);
+
+/* super.c */
+extern struct inode *nilfs_alloc_inode(struct super_block *);
+extern void nilfs_destroy_inode(struct inode *);
+extern void nilfs_error(struct super_block *, const char *, const char *, ...)
+	__attribute__ ((format (printf, 3, 4)));
+extern void nilfs_warning(struct super_block *, const char *, const char *, ...)
+       __attribute__ ((format (printf, 3, 4)));
+extern struct nilfs_super_block *
+nilfs_read_super_block(struct super_block *, u64, int, struct buffer_head **);
+extern int nilfs_store_magic_and_option(struct super_block *,
+					struct nilfs_super_block *, char *);
+extern int nilfs_commit_super(struct nilfs_sb_info *, int);
+extern int nilfs_attach_checkpoint(struct nilfs_sb_info *, __u64);
+extern void nilfs_detach_checkpoint(struct nilfs_sb_info *);
+
+/* gcinode.c */
+int nilfs_gccache_submit_read_data(struct inode *, sector_t, sector_t, __u64,
+				   struct buffer_head **);
+int nilfs_gccache_submit_read_node(struct inode *, sector_t, __u64,
+				   struct buffer_head **);
+int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *);
+int nilfs_init_gccache(struct the_nilfs *);
+void nilfs_destroy_gccache(struct the_nilfs *);
+void nilfs_clear_gcinode(struct inode *);
+struct inode *nilfs_gc_iget(struct the_nilfs *, ino_t, __u64);
+void nilfs_remove_all_gcinode(struct the_nilfs *);
+
+/* gcdat.c */
+int nilfs_init_gcdat_inode(struct the_nilfs *);
+void nilfs_commit_gcdat_inode(struct the_nilfs *);
+void nilfs_clear_gcdat_inode(struct the_nilfs *);
+
+/*
+ * Inodes and files operations
+ */
+extern struct file_operations nilfs_dir_operations;
+extern struct inode_operations nilfs_file_inode_operations;
+extern struct file_operations nilfs_file_operations;
+extern struct address_space_operations nilfs_aops;
+extern struct inode_operations nilfs_dir_inode_operations;
+extern struct inode_operations nilfs_special_inode_operations;
+extern struct inode_operations nilfs_symlink_inode_operations;
+
+/*
+ * filesystem type
+ */
+extern struct file_system_type nilfs_fs_type;
+
+
+#endif	/* _NILFS_H */
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
new file mode 100644
index 00000000000..1bfbba9c0e9
--- /dev/null
+++ b/fs/nilfs2/page.c
@@ -0,0 +1,540 @@
+/*
+ * page.c - buffer/page management specific to NILFS
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>,
+ *            Seiji Kihara <kihara@osrg.net>.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/swap.h>
+#include <linux/bitops.h>
+#include <linux/page-flags.h>
+#include <linux/list.h>
+#include <linux/highmem.h>
+#include <linux/pagevec.h>
+#include "nilfs.h"
+#include "page.h"
+#include "mdt.h"
+
+
+#define NILFS_BUFFER_INHERENT_BITS  \
+	((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
+	 (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated))
+
+static struct buffer_head *
+__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
+		       int blkbits, unsigned long b_state)
+
+{
+	unsigned long first_block;
+	struct buffer_head *bh;
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, 1 << blkbits, b_state);
+
+	first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
+	bh = nilfs_page_get_nth_block(page, block - first_block);
+
+	touch_buffer(bh);
+	wait_on_buffer(bh);
+	return bh;
+}
+
+/*
+ * Since the page cache of B-tree node pages or data page cache of pseudo
+ * inodes does not have a valid mapping->host pointer, calling
+ * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
+ * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
+ * To avoid this problem, the old style mark_buffer_dirty() is used instead.
+ */
+void nilfs_mark_buffer_dirty(struct buffer_head *bh)
+{
+	if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
+		__set_page_dirty_nobuffers(bh->b_page);
+}
+
+struct buffer_head *nilfs_grab_buffer(struct inode *inode,
+				      struct address_space *mapping,
+				      unsigned long blkoff,
+				      unsigned long b_state)
+{
+	int blkbits = inode->i_blkbits;
+	pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
+	struct page *page, *opage;
+	struct buffer_head *bh, *obh;
+
+	page = grab_cache_page(mapping, index);
+	if (unlikely(!page))
+		return NULL;
+
+	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
+	if (unlikely(!bh)) {
+		unlock_page(page);
+		page_cache_release(page);
+		return NULL;
+	}
+	if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
+		/*
+		 * Shadow page cache uses assoc_mapping to point its original
+		 * page cache.  The following code tries the original cache
+		 * if the given cache is a shadow and it didn't hit.
+		 */
+		opage = find_lock_page(mapping->assoc_mapping, index);
+		if (!opage)
+			return bh;
+
+		obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
+					     b_state);
+		if (buffer_uptodate(obh)) {
+			nilfs_copy_buffer(bh, obh);
+			if (buffer_dirty(obh)) {
+				nilfs_mark_buffer_dirty(bh);
+				if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
+					nilfs_mdt_mark_dirty(inode);
+			}
+		}
+		brelse(obh);
+		unlock_page(opage);
+		page_cache_release(opage);
+	}
+	return bh;
+}
+
+/**
+ * nilfs_forget_buffer - discard dirty state
+ * @inode: owner inode of the buffer
+ * @bh: buffer head of the buffer to be discarded
+ */
+void nilfs_forget_buffer(struct buffer_head *bh)
+{
+	struct page *page = bh->b_page;
+
+	lock_buffer(bh);
+	clear_buffer_nilfs_volatile(bh);
+	if (test_clear_buffer_dirty(bh) && nilfs_page_buffers_clean(page))
+		__nilfs_clear_page_dirty(page);
+
+	clear_buffer_uptodate(bh);
+	clear_buffer_mapped(bh);
+	bh->b_blocknr = -1;
+	ClearPageUptodate(page);
+	ClearPageMappedToDisk(page);
+	unlock_buffer(bh);
+	brelse(bh);
+}
+
+/**
+ * nilfs_copy_buffer -- copy buffer data and flags
+ * @dbh: destination buffer
+ * @sbh: source buffer
+ */
+void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
+{
+	void *kaddr0, *kaddr1;
+	unsigned long bits;
+	struct page *spage = sbh->b_page, *dpage = dbh->b_page;
+	struct buffer_head *bh;
+
+	kaddr0 = kmap_atomic(spage, KM_USER0);
+	kaddr1 = kmap_atomic(dpage, KM_USER1);
+	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
+	kunmap_atomic(kaddr1, KM_USER1);
+	kunmap_atomic(kaddr0, KM_USER0);
+
+	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
+	dbh->b_blocknr = sbh->b_blocknr;
+	dbh->b_bdev = sbh->b_bdev;
+
+	bh = dbh;
+	bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
+	while ((bh = bh->b_this_page) != dbh) {
+		lock_buffer(bh);
+		bits &= bh->b_state;
+		unlock_buffer(bh);
+	}
+	if (bits & (1UL << BH_Uptodate))
+		SetPageUptodate(dpage);
+	else
+		ClearPageUptodate(dpage);
+	if (bits & (1UL << BH_Mapped))
+		SetPageMappedToDisk(dpage);
+	else
+		ClearPageMappedToDisk(dpage);
+}
+
+/**
+ * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
+ * @page: page to be checked
+ *
+ * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
+ * Otherwise, it returns non-zero value.
+ */
+int nilfs_page_buffers_clean(struct page *page)
+{
+	struct buffer_head *bh, *head;
+
+	bh = head = page_buffers(page);
+	do {
+		if (buffer_dirty(bh))
+			return 0;
+		bh = bh->b_this_page;
+	} while (bh != head);
+	return 1;
+}
+
+void nilfs_page_bug(struct page *page)
+{
+	struct address_space *m;
+	unsigned long ino = 0;
+
+	if (unlikely(!page)) {
+		printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
+		return;
+	}
+
+	m = page->mapping;
+	if (m) {
+		struct inode *inode = NILFS_AS_I(m);
+		if (inode != NULL)
+			ino = inode->i_ino;
+	}
+	printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
+	       "mapping=%p ino=%lu\n",
+	       page, atomic_read(&page->_count),
+	       (unsigned long long)page->index, page->flags, m, ino);
+
+	if (page_has_buffers(page)) {
+		struct buffer_head *bh, *head;
+		int i = 0;
+
+		bh = head = page_buffers(page);
+		do {
+			printk(KERN_CRIT
+			       " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
+			       i++, bh, atomic_read(&bh->b_count),
+			       (unsigned long long)bh->b_blocknr, bh->b_state);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+}
+
+/**
+ * nilfs_alloc_private_page - allocate a private page with buffer heads
+ *
+ * Return Value: On success, a pointer to the allocated page is returned.
+ * On error, NULL is returned.
+ */
+struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
+				      unsigned long state)
+{
+	struct buffer_head *bh, *head, *tail;
+	struct page *page;
+
+	page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
+	if (unlikely(!page))
+		return NULL;
+
+	lock_page(page);
+	head = alloc_page_buffers(page, size, 0);
+	if (unlikely(!head)) {
+		unlock_page(page);
+		__free_page(page);
+		return NULL;
+	}
+
+	bh = head;
+	do {
+		bh->b_state = (1UL << BH_NILFS_Allocated) | state;
+		tail = bh;
+		bh->b_bdev = bdev;
+		bh = bh->b_this_page;
+	} while (bh);
+
+	tail->b_this_page = head;
+	attach_page_buffers(page, head);
+
+	return page;
+}
+
+void nilfs_free_private_page(struct page *page)
+{
+	BUG_ON(!PageLocked(page));
+	BUG_ON(page->mapping);
+
+	if (page_has_buffers(page) && !try_to_free_buffers(page))
+		NILFS_PAGE_BUG(page, "failed to free page");
+
+	unlock_page(page);
+	__free_page(page);
+}
+
+/**
+ * nilfs_copy_page -- copy the page with buffers
+ * @dst: destination page
+ * @src: source page
+ * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
+ *
+ * This fuction is for both data pages and btnode pages.  The dirty flag
+ * should be treated by caller.  The page must not be under i/o.
+ * Both src and dst page must be locked
+ */
+static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
+{
+	struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
+	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
+
+	BUG_ON(PageWriteback(dst));
+
+	sbh = sbufs = page_buffers(src);
+	if (!page_has_buffers(dst))
+		create_empty_buffers(dst, sbh->b_size, 0);
+
+	if (copy_dirty)
+		mask |= (1UL << BH_Dirty);
+
+	dbh = dbufs = page_buffers(dst);
+	do {
+		lock_buffer(sbh);
+		lock_buffer(dbh);
+		dbh->b_state = sbh->b_state & mask;
+		dbh->b_blocknr = sbh->b_blocknr;
+		dbh->b_bdev = sbh->b_bdev;
+		sbh = sbh->b_this_page;
+		dbh = dbh->b_this_page;
+	} while (dbh != dbufs);
+
+	copy_highpage(dst, src);
+
+	if (PageUptodate(src) && !PageUptodate(dst))
+		SetPageUptodate(dst);
+	else if (!PageUptodate(src) && PageUptodate(dst))
+		ClearPageUptodate(dst);
+	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
+		SetPageMappedToDisk(dst);
+	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
+		ClearPageMappedToDisk(dst);
+
+	do {
+		unlock_buffer(sbh);
+		unlock_buffer(dbh);
+		sbh = sbh->b_this_page;
+		dbh = dbh->b_this_page;
+	} while (dbh != dbufs);
+}
+
+int nilfs_copy_dirty_pages(struct address_space *dmap,
+			   struct address_space *smap)
+{
+	struct pagevec pvec;
+	unsigned int i;
+	pgoff_t index = 0;
+	int err = 0;
+
+	pagevec_init(&pvec, 0);
+repeat:
+	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
+				PAGEVEC_SIZE))
+		return 0;
+
+	for (i = 0; i < pagevec_count(&pvec); i++) {
+		struct page *page = pvec.pages[i], *dpage;
+
+		lock_page(page);
+		if (unlikely(!PageDirty(page)))
+			NILFS_PAGE_BUG(page, "inconsistent dirty state");
+
+		dpage = grab_cache_page(dmap, page->index);
+		if (unlikely(!dpage)) {
+			/* No empty page is added to the page cache */
+			err = -ENOMEM;
+			unlock_page(page);
+			break;
+		}
+		if (unlikely(!page_has_buffers(page)))
+			NILFS_PAGE_BUG(page,
+				       "found empty page in dat page cache");
+
+		nilfs_copy_page(dpage, page, 1);
+		__set_page_dirty_nobuffers(dpage);
+
+		unlock_page(dpage);
+		page_cache_release(dpage);
+		unlock_page(page);
+	}
+	pagevec_release(&pvec);
+	cond_resched();
+
+	if (likely(!err))
+		goto repeat;
+	return err;
+}
+
+/**
+ * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache
+ * @dmap: destination page cache
+ * @smap: source page cache
+ *
+ * No pages must no be added to the cache during this process.
+ * This must be ensured by the caller.
+ */
+void nilfs_copy_back_pages(struct address_space *dmap,
+			   struct address_space *smap)
+{
+	struct pagevec pvec;
+	unsigned int i, n;
+	pgoff_t index = 0;
+	int err;
+
+	pagevec_init(&pvec, 0);
+repeat:
+	n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
+	if (!n)
+		return;
+	index = pvec.pages[n - 1]->index + 1;
+
+	for (i = 0; i < pagevec_count(&pvec); i++) {
+		struct page *page = pvec.pages[i], *dpage;
+		pgoff_t offset = page->index;
+
+		lock_page(page);
+		dpage = find_lock_page(dmap, offset);
+		if (dpage) {
+			/* override existing page on the destination cache */
+			WARN_ON(PageDirty(dpage));
+			nilfs_copy_page(dpage, page, 0);
+			unlock_page(dpage);
+			page_cache_release(dpage);
+		} else {
+			struct page *page2;
+
+			/* move the page to the destination cache */
+			spin_lock_irq(&smap->tree_lock);
+			page2 = radix_tree_delete(&smap->page_tree, offset);
+			WARN_ON(page2 != page);
+
+			smap->nrpages--;
+			spin_unlock_irq(&smap->tree_lock);
+
+			spin_lock_irq(&dmap->tree_lock);
+			err = radix_tree_insert(&dmap->page_tree, offset, page);
+			if (unlikely(err < 0)) {
+				WARN_ON(err == -EEXIST);
+				page->mapping = NULL;
+				page_cache_release(page); /* for cache */
+			} else {
+				page->mapping = dmap;
+				dmap->nrpages++;
+				if (PageDirty(page))
+					radix_tree_tag_set(&dmap->page_tree,
+							   offset,
+							   PAGECACHE_TAG_DIRTY);
+			}
+			spin_unlock_irq(&dmap->tree_lock);
+		}
+		unlock_page(page);
+	}
+	pagevec_release(&pvec);
+	cond_resched();
+
+	goto repeat;
+}
+
+void nilfs_clear_dirty_pages(struct address_space *mapping)
+{
+	struct pagevec pvec;
+	unsigned int i;
+	pgoff_t index = 0;
+
+	pagevec_init(&pvec, 0);
+
+	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
+				  PAGEVEC_SIZE)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			struct page *page = pvec.pages[i];
+			struct buffer_head *bh, *head;
+
+			lock_page(page);
+			ClearPageUptodate(page);
+			ClearPageMappedToDisk(page);
+			bh = head = page_buffers(page);
+			do {
+				lock_buffer(bh);
+				clear_buffer_dirty(bh);
+				clear_buffer_nilfs_volatile(bh);
+				clear_buffer_uptodate(bh);
+				clear_buffer_mapped(bh);
+				unlock_buffer(bh);
+				bh = bh->b_this_page;
+			} while (bh != head);
+
+			__nilfs_clear_page_dirty(page);
+			unlock_page(page);
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+unsigned nilfs_page_count_clean_buffers(struct page *page,
+					unsigned from, unsigned to)
+{
+	unsigned block_start, block_end;
+	struct buffer_head *bh, *head;
+	unsigned nc = 0;
+
+	for (bh = head = page_buffers(page), block_start = 0;
+	     bh != head || !block_start;
+	     block_start = block_end, bh = bh->b_this_page) {
+		block_end = block_start + bh->b_size;
+		if (block_end > from && block_start < to && !buffer_dirty(bh))
+			nc++;
+	}
+	return nc;
+}
+
+/*
+ * NILFS2 needs clear_page_dirty() in the following two cases:
+ *
+ * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
+ *    page dirty flags when it copies back pages from the shadow cache
+ *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
+ *    (dat->{i_mapping,i_btnode_cache}).
+ *
+ * 2) Some B-tree operations like insertion or deletion may dispose buffers
+ *    in dirty state, and this needs to cancel the dirty state of their pages.
+ */
+int __nilfs_clear_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (mapping) {
+		spin_lock_irq(&mapping->tree_lock);
+		if (test_bit(PG_dirty, &page->flags)) {
+			radix_tree_tag_clear(&mapping->page_tree,
+					     page_index(page),
+					     PAGECACHE_TAG_DIRTY);
+			spin_unlock_irq(&mapping->tree_lock);
+			return clear_page_dirty_for_io(page);
+		}
+		spin_unlock_irq(&mapping->tree_lock);
+		return 0;
+	}
+	return TestClearPageDirty(page);
+}
diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
new file mode 100644
index 00000000000..8abca4d1c1f
--- /dev/null
+++ b/fs/nilfs2/page.h
@@ -0,0 +1,76 @@
+/*
+ * page.h - buffer/page management specific to NILFS
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>,
+ *            Seiji Kihara <kihara@osrg.net>.
+ */
+
+#ifndef _NILFS_PAGE_H
+#define _NILFS_PAGE_H
+
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+
+/*
+ * Extended buffer state bits
+ */
+enum {
+	BH_NILFS_Allocated = BH_PrivateStart,
+	BH_NILFS_Node,
+	BH_NILFS_Volatile,
+};
+
+BUFFER_FNS(NILFS_Allocated, nilfs_allocated)	/* nilfs private buffers */
+BUFFER_FNS(NILFS_Node, nilfs_node)		/* nilfs node buffers */
+BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
+
+
+void nilfs_mark_buffer_dirty(struct buffer_head *bh);
+int __nilfs_clear_page_dirty(struct page *);
+
+struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
+				      unsigned long, unsigned long);
+void nilfs_forget_buffer(struct buffer_head *);
+void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
+int nilfs_page_buffers_clean(struct page *);
+void nilfs_page_bug(struct page *);
+struct page *nilfs_alloc_private_page(struct block_device *, int,
+				      unsigned long);
+void nilfs_free_private_page(struct page *);
+
+int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
+void nilfs_copy_back_pages(struct address_space *, struct address_space *);
+void nilfs_clear_dirty_pages(struct address_space *);
+unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
+
+#define NILFS_PAGE_BUG(page, m, a...) \
+	do { nilfs_page_bug(page); BUG(); } while (0)
+
+static inline struct buffer_head *
+nilfs_page_get_nth_block(struct page *page, unsigned int count)
+{
+	struct buffer_head *bh = page_buffers(page);
+
+	while (count-- > 0)
+		bh = bh->b_this_page;
+	get_bh(bh);
+	return bh;
+}
+
+#endif /* _NILFS_PAGE_H */
diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
new file mode 100644
index 00000000000..6ade0963fc1
--- /dev/null
+++ b/fs/nilfs2/recovery.c
@@ -0,0 +1,929 @@
+/*
+ * recovery.c - NILFS recovery logic
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/swap.h>
+#include <linux/crc32.h>
+#include "nilfs.h"
+#include "segment.h"
+#include "sufile.h"
+#include "page.h"
+#include "seglist.h"
+#include "segbuf.h"
+
+/*
+ * Segment check result
+ */
+enum {
+	NILFS_SEG_VALID,
+	NILFS_SEG_NO_SUPER_ROOT,
+	NILFS_SEG_FAIL_IO,
+	NILFS_SEG_FAIL_MAGIC,
+	NILFS_SEG_FAIL_SEQ,
+	NILFS_SEG_FAIL_CHECKSUM_SEGSUM,
+	NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT,
+	NILFS_SEG_FAIL_CHECKSUM_FULL,
+	NILFS_SEG_FAIL_CONSISTENCY,
+};
+
+/* work structure for recovery */
+struct nilfs_recovery_block {
+	ino_t ino;		/* Inode number of the file that this block
+				   belongs to */
+	sector_t blocknr;	/* block number */
+	__u64 vblocknr;		/* virtual block number */
+	unsigned long blkoff;	/* File offset of the data block (per block) */
+	struct list_head list;
+};
+
+
+static int nilfs_warn_segment_error(int err)
+{
+	switch (err) {
+	case NILFS_SEG_FAIL_IO:
+		printk(KERN_WARNING
+		       "NILFS warning: I/O error on loading last segment\n");
+		return -EIO;
+	case NILFS_SEG_FAIL_MAGIC:
+		printk(KERN_WARNING
+		       "NILFS warning: Segment magic number invalid\n");
+		break;
+	case NILFS_SEG_FAIL_SEQ:
+		printk(KERN_WARNING
+		       "NILFS warning: Sequence number mismatch\n");
+		break;
+	case NILFS_SEG_FAIL_CHECKSUM_SEGSUM:
+		printk(KERN_WARNING
+		       "NILFS warning: Checksum error in segment summary\n");
+		break;
+	case NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT:
+		printk(KERN_WARNING
+		       "NILFS warning: Checksum error in super root\n");
+		break;
+	case NILFS_SEG_FAIL_CHECKSUM_FULL:
+		printk(KERN_WARNING
+		       "NILFS warning: Checksum error in segment payload\n");
+		break;
+	case NILFS_SEG_FAIL_CONSISTENCY:
+		printk(KERN_WARNING
+		       "NILFS warning: Inconsistent segment\n");
+		break;
+	case NILFS_SEG_NO_SUPER_ROOT:
+		printk(KERN_WARNING
+		       "NILFS warning: No super root in the last segment\n");
+		break;
+	}
+	return -EINVAL;
+}
+
+static void store_segsum_info(struct nilfs_segsum_info *ssi,
+			      struct nilfs_segment_summary *sum,
+			      unsigned int blocksize)
+{
+	ssi->flags = le16_to_cpu(sum->ss_flags);
+	ssi->seg_seq = le64_to_cpu(sum->ss_seq);
+	ssi->ctime = le64_to_cpu(sum->ss_create);
+	ssi->next = le64_to_cpu(sum->ss_next);
+	ssi->nblocks = le32_to_cpu(sum->ss_nblocks);
+	ssi->nfinfo = le32_to_cpu(sum->ss_nfinfo);
+	ssi->sumbytes = le32_to_cpu(sum->ss_sumbytes);
+
+	ssi->nsumblk = DIV_ROUND_UP(ssi->sumbytes, blocksize);
+	ssi->nfileblk = ssi->nblocks - ssi->nsumblk - !!NILFS_SEG_HAS_SR(ssi);
+}
+
+/**
+ * calc_crc_cont - check CRC of blocks continuously
+ * @sbi: nilfs_sb_info
+ * @bhs: buffer head of start block
+ * @sum: place to store result
+ * @offset: offset bytes in the first block
+ * @check_bytes: number of bytes to be checked
+ * @start: DBN of start block
+ * @nblock: number of blocks to be checked
+ */
+static int calc_crc_cont(struct nilfs_sb_info *sbi, struct buffer_head *bhs,
+			 u32 *sum, unsigned long offset, u64 check_bytes,
+			 sector_t start, unsigned long nblock)
+{
+	unsigned long blocksize = sbi->s_super->s_blocksize;
+	unsigned long size;
+	u32 crc;
+
+	BUG_ON(offset >= blocksize);
+	check_bytes -= offset;
+	size = min_t(u64, check_bytes, blocksize - offset);
+	crc = crc32_le(sbi->s_nilfs->ns_crc_seed,
+		       (unsigned char *)bhs->b_data + offset, size);
+	if (--nblock > 0) {
+		do {
+			struct buffer_head *bh
+				= sb_bread(sbi->s_super, ++start);
+			if (!bh)
+				return -EIO;
+			check_bytes -= size;
+			size = min_t(u64, check_bytes, blocksize);
+			crc = crc32_le(crc, bh->b_data, size);
+			brelse(bh);
+		} while (--nblock > 0);
+	}
+	*sum = crc;
+	return 0;
+}
+
+/**
+ * nilfs_read_super_root_block - read super root block
+ * @sb: super_block
+ * @sr_block: disk block number of the super root block
+ * @pbh: address of a buffer_head pointer to return super root buffer
+ * @check: CRC check flag
+ */
+int nilfs_read_super_root_block(struct super_block *sb, sector_t sr_block,
+				struct buffer_head **pbh, int check)
+{
+	struct buffer_head *bh_sr;
+	struct nilfs_super_root *sr;
+	u32 crc;
+	int ret;
+
+	*pbh = NULL;
+	bh_sr = sb_bread(sb, sr_block);
+	if (unlikely(!bh_sr)) {
+		ret = NILFS_SEG_FAIL_IO;
+		goto failed;
+	}
+
+	sr = (struct nilfs_super_root *)bh_sr->b_data;
+	if (check) {
+		unsigned bytes = le16_to_cpu(sr->sr_bytes);
+
+		if (bytes == 0 || bytes > sb->s_blocksize) {
+			ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
+			goto failed_bh;
+		}
+		if (calc_crc_cont(NILFS_SB(sb), bh_sr, &crc,
+				  sizeof(sr->sr_sum), bytes, sr_block, 1)) {
+			ret = NILFS_SEG_FAIL_IO;
+			goto failed_bh;
+		}
+		if (crc != le32_to_cpu(sr->sr_sum)) {
+			ret = NILFS_SEG_FAIL_CHECKSUM_SUPER_ROOT;
+			goto failed_bh;
+		}
+	}
+	*pbh = bh_sr;
+	return 0;
+
+ failed_bh:
+	brelse(bh_sr);
+
+ failed:
+	return nilfs_warn_segment_error(ret);
+}
+
+/**
+ * load_segment_summary - read segment summary of the specified partial segment
+ * @sbi: nilfs_sb_info
+ * @pseg_start: start disk block number of partial segment
+ * @seg_seq: sequence number requested
+ * @ssi: pointer to nilfs_segsum_info struct to store information
+ * @full_check: full check flag
+ *              (0: only checks segment summary CRC, 1: data CRC)
+ */
+static int
+load_segment_summary(struct nilfs_sb_info *sbi, sector_t pseg_start,
+		     u64 seg_seq, struct nilfs_segsum_info *ssi,
+		     int full_check)
+{
+	struct buffer_head *bh_sum;
+	struct nilfs_segment_summary *sum;
+	unsigned long offset, nblock;
+	u64 check_bytes;
+	u32 crc, crc_sum;
+	int ret = NILFS_SEG_FAIL_IO;
+
+	bh_sum = sb_bread(sbi->s_super, pseg_start);
+	if (!bh_sum)
+		goto out;
+
+	sum = (struct nilfs_segment_summary *)bh_sum->b_data;
+
+	/* Check consistency of segment summary */
+	if (le32_to_cpu(sum->ss_magic) != NILFS_SEGSUM_MAGIC) {
+		ret = NILFS_SEG_FAIL_MAGIC;
+		goto failed;
+	}
+	store_segsum_info(ssi, sum, sbi->s_super->s_blocksize);
+	if (seg_seq != ssi->seg_seq) {
+		ret = NILFS_SEG_FAIL_SEQ;
+		goto failed;
+	}
+	if (full_check) {
+		offset = sizeof(sum->ss_datasum);
+		check_bytes =
+			((u64)ssi->nblocks << sbi->s_super->s_blocksize_bits);
+		nblock = ssi->nblocks;
+		crc_sum = le32_to_cpu(sum->ss_datasum);
+		ret = NILFS_SEG_FAIL_CHECKSUM_FULL;
+	} else { /* only checks segment summary */
+		offset = sizeof(sum->ss_datasum) + sizeof(sum->ss_sumsum);
+		check_bytes = ssi->sumbytes;
+		nblock = ssi->nsumblk;
+		crc_sum = le32_to_cpu(sum->ss_sumsum);
+		ret = NILFS_SEG_FAIL_CHECKSUM_SEGSUM;
+	}
+
+	if (unlikely(nblock == 0 ||
+		     nblock > sbi->s_nilfs->ns_blocks_per_segment)) {
+		/* This limits the number of blocks read in the CRC check */
+		ret = NILFS_SEG_FAIL_CONSISTENCY;
+		goto failed;
+	}
+	if (calc_crc_cont(sbi, bh_sum, &crc, offset, check_bytes,
+			  pseg_start, nblock)) {
+		ret = NILFS_SEG_FAIL_IO;
+		goto failed;
+	}
+	if (crc == crc_sum)
+		ret = 0;
+ failed:
+	brelse(bh_sum);
+ out:
+	return ret;
+}
+
+static void *segsum_get(struct super_block *sb, struct buffer_head **pbh,
+			unsigned int *offset, unsigned int bytes)
+{
+	void *ptr;
+	sector_t blocknr;
+
+	BUG_ON((*pbh)->b_size < *offset);
+	if (bytes > (*pbh)->b_size - *offset) {
+		blocknr = (*pbh)->b_blocknr;
+		brelse(*pbh);
+		*pbh = sb_bread(sb, blocknr + 1);
+		if (unlikely(!*pbh))
+			return NULL;
+		*offset = 0;
+	}
+	ptr = (*pbh)->b_data + *offset;
+	*offset += bytes;
+	return ptr;
+}
+
+static void segsum_skip(struct super_block *sb, struct buffer_head **pbh,
+			unsigned int *offset, unsigned int bytes,
+			unsigned long count)
+{
+	unsigned int rest_item_in_current_block
+		= ((*pbh)->b_size - *offset) / bytes;
+
+	if (count <= rest_item_in_current_block) {
+		*offset += bytes * count;
+	} else {
+		sector_t blocknr = (*pbh)->b_blocknr;
+		unsigned int nitem_per_block = (*pbh)->b_size / bytes;
+		unsigned int bcnt;
+
+		count -= rest_item_in_current_block;
+		bcnt = DIV_ROUND_UP(count, nitem_per_block);
+		*offset = bytes * (count - (bcnt - 1) * nitem_per_block);
+
+		brelse(*pbh);
+		*pbh = sb_bread(sb, blocknr + bcnt);
+	}
+}
+
+static int
+collect_blocks_from_segsum(struct nilfs_sb_info *sbi, sector_t sum_blocknr,
+			   struct nilfs_segsum_info *ssi,
+			   struct list_head *head)
+{
+	struct buffer_head *bh;
+	unsigned int offset;
+	unsigned long nfinfo = ssi->nfinfo;
+	sector_t blocknr = sum_blocknr + ssi->nsumblk;
+	ino_t ino;
+	int err = -EIO;
+
+	if (!nfinfo)
+		return 0;
+
+	bh = sb_bread(sbi->s_super, sum_blocknr);
+	if (unlikely(!bh))
+		goto out;
+
+	offset = le16_to_cpu(
+		((struct nilfs_segment_summary *)bh->b_data)->ss_bytes);
+	for (;;) {
+		unsigned long nblocks, ndatablk, nnodeblk;
+		struct nilfs_finfo *finfo;
+
+		finfo = segsum_get(sbi->s_super, &bh, &offset, sizeof(*finfo));
+		if (unlikely(!finfo))
+			goto out;
+
+		ino = le64_to_cpu(finfo->fi_ino);
+		nblocks = le32_to_cpu(finfo->fi_nblocks);
+		ndatablk = le32_to_cpu(finfo->fi_ndatablk);
+		nnodeblk = nblocks - ndatablk;
+
+		while (ndatablk-- > 0) {
+			struct nilfs_recovery_block *rb;
+			struct nilfs_binfo_v *binfo;
+
+			binfo = segsum_get(sbi->s_super, &bh, &offset,
+					   sizeof(*binfo));
+			if (unlikely(!binfo))
+				goto out;
+
+			rb = kmalloc(sizeof(*rb), GFP_NOFS);
+			if (unlikely(!rb)) {
+				err = -ENOMEM;
+				goto out;
+			}
+			rb->ino = ino;
+			rb->blocknr = blocknr++;
+			rb->vblocknr = le64_to_cpu(binfo->bi_vblocknr);
+			rb->blkoff = le64_to_cpu(binfo->bi_blkoff);
+			/* INIT_LIST_HEAD(&rb->list); */
+			list_add_tail(&rb->list, head);
+		}
+		if (--nfinfo == 0)
+			break;
+		blocknr += nnodeblk; /* always 0 for the data sync segments */
+		segsum_skip(sbi->s_super, &bh, &offset, sizeof(__le64),
+			    nnodeblk);
+		if (unlikely(!bh))
+			goto out;
+	}
+	err = 0;
+ out:
+	brelse(bh);   /* brelse(NULL) is just ignored */
+	return err;
+}
+
+static void dispose_recovery_list(struct list_head *head)
+{
+	while (!list_empty(head)) {
+		struct nilfs_recovery_block *rb
+			= list_entry(head->next,
+				     struct nilfs_recovery_block, list);
+		list_del(&rb->list);
+		kfree(rb);
+	}
+}
+
+void nilfs_dispose_segment_list(struct list_head *head)
+{
+	while (!list_empty(head)) {
+		struct nilfs_segment_entry *ent
+			= list_entry(head->next,
+				     struct nilfs_segment_entry, list);
+		list_del(&ent->list);
+		nilfs_free_segment_entry(ent);
+	}
+}
+
+static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
+					      struct nilfs_recovery_info *ri)
+{
+	struct list_head *head = &ri->ri_used_segments;
+	struct nilfs_segment_entry *ent, *n;
+	struct inode *sufile = nilfs->ns_sufile;
+	__u64 segnum[4];
+	time_t mtime;
+	int err;
+	int i;
+
+	segnum[0] = nilfs->ns_segnum;
+	segnum[1] = nilfs->ns_nextnum;
+	segnum[2] = ri->ri_segnum;
+	segnum[3] = ri->ri_nextnum;
+
+	/*
+	 * Releasing the next segment of the latest super root.
+	 * The next segment is invalidated by this recovery.
+	 */
+	err = nilfs_sufile_free(sufile, segnum[1]);
+	if (unlikely(err))
+		goto failed;
+
+	err = -ENOMEM;
+	for (i = 1; i < 4; i++) {
+		ent = nilfs_alloc_segment_entry(segnum[i]);
+		if (unlikely(!ent))
+			goto failed;
+		list_add_tail(&ent->list, head);
+	}
+
+	/*
+	 * Collecting segments written after the latest super root.
+	 * These are marked dirty to avoid being reallocated in the next write.
+	 */
+	mtime = get_seconds();
+	list_for_each_entry_safe(ent, n, head, list) {
+		if (ent->segnum == segnum[0]) {
+			list_del(&ent->list);
+			nilfs_free_segment_entry(ent);
+			continue;
+		}
+		err = nilfs_open_segment_entry(ent, sufile);
+		if (unlikely(err))
+			goto failed;
+		if (!nilfs_segment_usage_dirty(ent->raw_su)) {
+			/* make the segment garbage */
+			ent->raw_su->su_nblocks = cpu_to_le32(0);
+			ent->raw_su->su_lastmod = cpu_to_le32(mtime);
+			nilfs_segment_usage_set_dirty(ent->raw_su);
+		}
+		list_del(&ent->list);
+		nilfs_close_segment_entry(ent, sufile);
+		nilfs_free_segment_entry(ent);
+	}
+
+	/* Allocate new segments for recovery */
+	err = nilfs_sufile_alloc(sufile, &segnum[0]);
+	if (unlikely(err))
+		goto failed;
+
+	nilfs->ns_pseg_offset = 0;
+	nilfs->ns_seg_seq = ri->ri_seq + 2;
+	nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
+	return 0;
+
+ failed:
+	/* No need to recover sufile because it will be destroyed on error */
+	return err;
+}
+
+static int nilfs_recovery_copy_block(struct nilfs_sb_info *sbi,
+				     struct nilfs_recovery_block *rb,
+				     struct page *page)
+{
+	struct buffer_head *bh_org;
+	void *kaddr;
+
+	bh_org = sb_bread(sbi->s_super, rb->blocknr);
+	if (unlikely(!bh_org))
+		return -EIO;
+
+	kaddr = kmap_atomic(page, KM_USER0);
+	memcpy(kaddr + bh_offset(bh_org), bh_org->b_data, bh_org->b_size);
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(bh_org);
+	return 0;
+}
+
+static int recover_dsync_blocks(struct nilfs_sb_info *sbi,
+				struct list_head *head,
+				unsigned long *nr_salvaged_blocks)
+{
+	struct inode *inode;
+	struct nilfs_recovery_block *rb, *n;
+	unsigned blocksize = sbi->s_super->s_blocksize;
+	struct page *page;
+	loff_t pos;
+	int err = 0, err2 = 0;
+
+	list_for_each_entry_safe(rb, n, head, list) {
+		inode = nilfs_iget(sbi->s_super, rb->ino);
+		if (IS_ERR(inode)) {
+			err = PTR_ERR(inode);
+			inode = NULL;
+			goto failed_inode;
+		}
+
+		pos = rb->blkoff << inode->i_blkbits;
+		page = NULL;
+		err = block_write_begin(NULL, inode->i_mapping, pos, blocksize,
+					0, &page, NULL, nilfs_get_block);
+		if (unlikely(err))
+			goto failed_inode;
+
+		err = nilfs_recovery_copy_block(sbi, rb, page);
+		if (unlikely(err))
+			goto failed_page;
+
+		err = nilfs_set_file_dirty(sbi, inode, 1);
+		if (unlikely(err))
+			goto failed_page;
+
+		block_write_end(NULL, inode->i_mapping, pos, blocksize,
+				blocksize, page, NULL);
+
+		unlock_page(page);
+		page_cache_release(page);
+
+		(*nr_salvaged_blocks)++;
+		goto next;
+
+ failed_page:
+		unlock_page(page);
+		page_cache_release(page);
+
+ failed_inode:
+		printk(KERN_WARNING
+		       "NILFS warning: error recovering data block "
+		       "(err=%d, ino=%lu, block-offset=%llu)\n",
+		       err, rb->ino, (unsigned long long)rb->blkoff);
+		if (!err2)
+			err2 = err;
+ next:
+		iput(inode); /* iput(NULL) is just ignored */
+		list_del_init(&rb->list);
+		kfree(rb);
+	}
+	return err2;
+}
+
+/**
+ * nilfs_do_roll_forward - salvage logical segments newer than the latest
+ * checkpoint
+ * @sbi: nilfs_sb_info
+ * @nilfs: the_nilfs
+ * @ri: pointer to a nilfs_recovery_info
+ */
+static int nilfs_do_roll_forward(struct the_nilfs *nilfs,
+				 struct nilfs_sb_info *sbi,
+				 struct nilfs_recovery_info *ri)
+{
+	struct nilfs_segsum_info ssi;
+	sector_t pseg_start;
+	sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
+	unsigned long nsalvaged_blocks = 0;
+	u64 seg_seq;
+	__u64 segnum, nextnum = 0;
+	int empty_seg = 0;
+	int err = 0, ret;
+	LIST_HEAD(dsync_blocks);  /* list of data blocks to be recovered */
+	enum {
+		RF_INIT_ST,
+		RF_DSYNC_ST,   /* scanning data-sync segments */
+	};
+	int state = RF_INIT_ST;
+
+	nilfs_attach_writer(nilfs, sbi);
+	pseg_start = ri->ri_lsegs_start;
+	seg_seq = ri->ri_lsegs_start_seq;
+	segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
+	nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
+
+	while (segnum != ri->ri_segnum || pseg_start <= ri->ri_pseg_start) {
+
+		ret = load_segment_summary(sbi, pseg_start, seg_seq, &ssi, 1);
+		if (ret) {
+			if (ret == NILFS_SEG_FAIL_IO) {
+				err = -EIO;
+				goto failed;
+			}
+			goto strayed;
+		}
+		if (unlikely(NILFS_SEG_HAS_SR(&ssi)))
+			goto confused;
+
+		/* Found a valid partial segment; do recovery actions */
+		nextnum = nilfs_get_segnum_of_block(nilfs, ssi.next);
+		empty_seg = 0;
+		nilfs->ns_ctime = ssi.ctime;
+		if (!(ssi.flags & NILFS_SS_GC))
+			nilfs->ns_nongc_ctime = ssi.ctime;
+
+		switch (state) {
+		case RF_INIT_ST:
+			if (!NILFS_SEG_LOGBGN(&ssi) || !NILFS_SEG_DSYNC(&ssi))
+				goto try_next_pseg;
+			state = RF_DSYNC_ST;
+			/* Fall through */
+		case RF_DSYNC_ST:
+			if (!NILFS_SEG_DSYNC(&ssi))
+				goto confused;
+
+			err = collect_blocks_from_segsum(
+				sbi, pseg_start, &ssi, &dsync_blocks);
+			if (unlikely(err))
+				goto failed;
+			if (NILFS_SEG_LOGEND(&ssi)) {
+				err = recover_dsync_blocks(
+					sbi, &dsync_blocks, &nsalvaged_blocks);
+				if (unlikely(err))
+					goto failed;
+				state = RF_INIT_ST;
+			}
+			break; /* Fall through to try_next_pseg */
+		}
+
+ try_next_pseg:
+		if (pseg_start == ri->ri_lsegs_end)
+			break;
+		pseg_start += ssi.nblocks;
+		if (pseg_start < seg_end)
+			continue;
+		goto feed_segment;
+
+ strayed:
+		if (pseg_start == ri->ri_lsegs_end)
+			break;
+
+ feed_segment:
+		/* Looking to the next full segment */
+		if (empty_seg++)
+			break;
+		seg_seq++;
+		segnum = nextnum;
+		nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
+		pseg_start = seg_start;
+	}
+
+	if (nsalvaged_blocks) {
+		printk(KERN_INFO "NILFS (device %s): salvaged %lu blocks\n",
+		       sbi->s_super->s_id, nsalvaged_blocks);
+		ri->ri_need_recovery = NILFS_RECOVERY_ROLLFORWARD_DONE;
+	}
+ out:
+	dispose_recovery_list(&dsync_blocks);
+	nilfs_detach_writer(sbi->s_nilfs, sbi);
+	return err;
+
+ confused:
+	err = -EINVAL;
+ failed:
+	printk(KERN_ERR
+	       "NILFS (device %s): Error roll-forwarding "
+	       "(err=%d, pseg block=%llu). ",
+	       sbi->s_super->s_id, err, (unsigned long long)pseg_start);
+	goto out;
+}
+
+static void nilfs_finish_roll_forward(struct the_nilfs *nilfs,
+				      struct nilfs_sb_info *sbi,
+				      struct nilfs_recovery_info *ri)
+{
+	struct buffer_head *bh;
+	int err;
+
+	if (nilfs_get_segnum_of_block(nilfs, ri->ri_lsegs_start) !=
+	    nilfs_get_segnum_of_block(nilfs, ri->ri_super_root))
+		return;
+
+	bh = sb_getblk(sbi->s_super, ri->ri_lsegs_start);
+	BUG_ON(!bh);
+	memset(bh->b_data, 0, bh->b_size);
+	set_buffer_dirty(bh);
+	err = sync_dirty_buffer(bh);
+	if (unlikely(err))
+		printk(KERN_WARNING
+		       "NILFS warning: buffer sync write failed during "
+		       "post-cleaning of recovery.\n");
+	brelse(bh);
+}
+
+/**
+ * nilfs_recover_logical_segments - salvage logical segments written after
+ * the latest super root
+ * @nilfs: the_nilfs
+ * @sbi: nilfs_sb_info
+ * @ri: pointer to a nilfs_recovery_info struct to store search results.
+ *
+ * Return Value: On success, 0 is returned.  On error, one of the following
+ * negative error code is returned.
+ *
+ * %-EINVAL - Inconsistent filesystem state.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOSPC - No space left on device (only in a panic state).
+ *
+ * %-ERESTARTSYS - Interrupted.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ */
+int nilfs_recover_logical_segments(struct the_nilfs *nilfs,
+				   struct nilfs_sb_info *sbi,
+				   struct nilfs_recovery_info *ri)
+{
+	int err;
+
+	if (ri->ri_lsegs_start == 0 || ri->ri_lsegs_end == 0)
+		return 0;
+
+	err = nilfs_attach_checkpoint(sbi, ri->ri_cno);
+	if (unlikely(err)) {
+		printk(KERN_ERR
+		       "NILFS: error loading the latest checkpoint.\n");
+		return err;
+	}
+
+	err = nilfs_do_roll_forward(nilfs, sbi, ri);
+	if (unlikely(err))
+		goto failed;
+
+	if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
+		err = nilfs_prepare_segment_for_recovery(nilfs, ri);
+		if (unlikely(err)) {
+			printk(KERN_ERR "NILFS: Error preparing segments for "
+			       "recovery.\n");
+			goto failed;
+		}
+
+		err = nilfs_attach_segment_constructor(sbi);
+		if (unlikely(err))
+			goto failed;
+
+		set_nilfs_discontinued(nilfs);
+		err = nilfs_construct_segment(sbi->s_super);
+		nilfs_detach_segment_constructor(sbi);
+
+		if (unlikely(err)) {
+			printk(KERN_ERR "NILFS: Oops! recovery failed. "
+			       "(err=%d)\n", err);
+			goto failed;
+		}
+
+		nilfs_finish_roll_forward(nilfs, sbi, ri);
+	}
+
+	nilfs_detach_checkpoint(sbi);
+	return 0;
+
+ failed:
+	nilfs_detach_checkpoint(sbi);
+	nilfs_mdt_clear(nilfs->ns_cpfile);
+	nilfs_mdt_clear(nilfs->ns_sufile);
+	nilfs_mdt_clear(nilfs->ns_dat);
+	return err;
+}
+
+/**
+ * nilfs_search_super_root - search the latest valid super root
+ * @nilfs: the_nilfs
+ * @sbi: nilfs_sb_info
+ * @ri: pointer to a nilfs_recovery_info struct to store search results.
+ *
+ * nilfs_search_super_root() looks for the latest super-root from a partial
+ * segment pointed by the superblock.  It sets up struct the_nilfs through
+ * this search. It fills nilfs_recovery_info (ri) required for recovery.
+ *
+ * Return Value: On success, 0 is returned.  On error, one of the following
+ * negative error code is returned.
+ *
+ * %-EINVAL - No valid segment found
+ *
+ * %-EIO - I/O error
+ */
+int nilfs_search_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi,
+			    struct nilfs_recovery_info *ri)
+{
+	struct nilfs_segsum_info ssi;
+	sector_t pseg_start, pseg_end, sr_pseg_start = 0;
+	sector_t seg_start, seg_end; /* range of full segment (block number) */
+	u64 seg_seq;
+	__u64 segnum, nextnum = 0;
+	__u64 cno;
+	struct nilfs_segment_entry *ent;
+	LIST_HEAD(segments);
+	int empty_seg = 0, scan_newer = 0;
+	int ret;
+
+	pseg_start = nilfs->ns_last_pseg;
+	seg_seq = nilfs->ns_last_seq;
+	cno = nilfs->ns_last_cno;
+	segnum = nilfs_get_segnum_of_block(nilfs, pseg_start);
+
+	/* Calculate range of segment */
+	nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
+
+	for (;;) {
+		/* Load segment summary */
+		ret = load_segment_summary(sbi, pseg_start, seg_seq, &ssi, 1);
+		if (ret) {
+			if (ret == NILFS_SEG_FAIL_IO)
+				goto failed;
+			goto strayed;
+		}
+		pseg_end = pseg_start + ssi.nblocks - 1;
+		if (unlikely(pseg_end > seg_end)) {
+			ret = NILFS_SEG_FAIL_CONSISTENCY;
+			goto strayed;
+		}
+
+		/* A valid partial segment */
+		ri->ri_pseg_start = pseg_start;
+		ri->ri_seq = seg_seq;
+		ri->ri_segnum = segnum;
+		nextnum = nilfs_get_segnum_of_block(nilfs, ssi.next);
+		ri->ri_nextnum = nextnum;
+		empty_seg = 0;
+
+		if (!NILFS_SEG_HAS_SR(&ssi)) {
+			if (!scan_newer) {
+				/* This will never happen because a superblock
+				   (last_segment) always points to a pseg
+				   having a super root. */
+				ret = NILFS_SEG_FAIL_CONSISTENCY;
+				goto failed;
+			}
+			if (!ri->ri_lsegs_start && NILFS_SEG_LOGBGN(&ssi)) {
+				ri->ri_lsegs_start = pseg_start;
+				ri->ri_lsegs_start_seq = seg_seq;
+			}
+			if (NILFS_SEG_LOGEND(&ssi))
+				ri->ri_lsegs_end = pseg_start;
+			goto try_next_pseg;
+		}
+
+		/* A valid super root was found. */
+		ri->ri_cno = cno++;
+		ri->ri_super_root = pseg_end;
+		ri->ri_lsegs_start = ri->ri_lsegs_end = 0;
+
+		nilfs_dispose_segment_list(&segments);
+		nilfs->ns_pseg_offset = (sr_pseg_start = pseg_start)
+			+ ssi.nblocks - seg_start;
+		nilfs->ns_seg_seq = seg_seq;
+		nilfs->ns_segnum = segnum;
+		nilfs->ns_cno = cno;  /* nilfs->ns_cno = ri->ri_cno + 1 */
+		nilfs->ns_ctime = ssi.ctime;
+		nilfs->ns_nextnum = nextnum;
+
+		if (scan_newer)
+			ri->ri_need_recovery = NILFS_RECOVERY_SR_UPDATED;
+		else {
+			if (nilfs->ns_mount_state & NILFS_VALID_FS)
+				goto super_root_found;
+			scan_newer = 1;
+		}
+
+		/* reset region for roll-forward */
+		pseg_start += ssi.nblocks;
+		if (pseg_start < seg_end)
+			continue;
+		goto feed_segment;
+
+ try_next_pseg:
+		/* Standing on a course, or met an inconsistent state */
+		pseg_start += ssi.nblocks;
+		if (pseg_start < seg_end)
+			continue;
+		goto feed_segment;
+
+ strayed:
+		/* Off the trail */
+		if (!scan_newer)
+			/*
+			 * This can happen if a checkpoint was written without
+			 * barriers, or as a result of an I/O failure.
+			 */
+			goto failed;
+
+ feed_segment:
+		/* Looking to the next full segment */
+		if (empty_seg++)
+			goto super_root_found; /* found a valid super root */
+
+		ent = nilfs_alloc_segment_entry(segnum);
+		if (unlikely(!ent)) {
+			ret = -ENOMEM;
+			goto failed;
+		}
+		list_add_tail(&ent->list, &segments);
+
+		seg_seq++;
+		segnum = nextnum;
+		nilfs_get_segment_range(nilfs, segnum, &seg_start, &seg_end);
+		pseg_start = seg_start;
+	}
+
+ super_root_found:
+	/* Updating pointers relating to the latest checkpoint */
+	list_splice(&segments, ri->ri_used_segments.prev);
+	nilfs->ns_last_pseg = sr_pseg_start;
+	nilfs->ns_last_seq = nilfs->ns_seg_seq;
+	nilfs->ns_last_cno = ri->ri_cno;
+	return 0;
+
+ failed:
+	nilfs_dispose_segment_list(&segments);
+	return (ret < 0) ? ret : nilfs_warn_segment_error(ret);
+}
diff --git a/fs/nilfs2/sb.h b/fs/nilfs2/sb.h
new file mode 100644
index 00000000000..adccd4fc654
--- /dev/null
+++ b/fs/nilfs2/sb.h
@@ -0,0 +1,102 @@
+/*
+ * sb.h - NILFS on-memory super block structure.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#ifndef _NILFS_SB
+#define _NILFS_SB
+
+#include <linux/types.h>
+#include <linux/fs.h>
+
+/*
+ * Mount options
+ */
+struct nilfs_mount_options {
+	unsigned long mount_opt;
+	__u64 snapshot_cno;
+};
+
+struct the_nilfs;
+struct nilfs_sc_info;
+
+/*
+ * NILFS super-block data in memory
+ */
+struct nilfs_sb_info {
+	/* Snapshot status */
+	__u64 s_snapshot_cno;		/* Checkpoint number */
+	atomic_t s_inodes_count;
+	atomic_t s_blocks_count;	/* Reserved (might be deleted) */
+
+	/* Mount options */
+	unsigned long s_mount_opt;
+	uid_t s_resuid;
+	gid_t s_resgid;
+
+	unsigned long s_interval;	/* construction interval */
+	unsigned long s_watermark;	/* threshold of data amount
+					   for the segment construction */
+
+	/* Fundamental members */
+	struct super_block *s_super;	/* reverse pointer to super_block */
+	struct the_nilfs *s_nilfs;
+	struct list_head s_list;	/* list head for nilfs->ns_supers */
+
+	/* Segment constructor */
+	struct list_head s_dirty_files;	/* dirty files list */
+	struct nilfs_sc_info *s_sc_info; /* segment constructor info */
+	spinlock_t s_inode_lock;	/* Lock for the nilfs inode.
+					   It covers s_dirty_files list */
+
+	/* Metadata files */
+	struct inode *s_ifile;		/* index file inode */
+
+	/* Inode allocator */
+	spinlock_t s_next_gen_lock;
+	u32 s_next_generation;
+};
+
+static inline struct nilfs_sb_info *NILFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static inline struct nilfs_sc_info *NILFS_SC(struct nilfs_sb_info *sbi)
+{
+	return sbi->s_sc_info;
+}
+
+/*
+ * Bit operations for the mount option
+ */
+#define nilfs_clear_opt(sbi, opt)  \
+	do { (sbi)->s_mount_opt &= ~NILFS_MOUNT_##opt; } while (0)
+#define nilfs_set_opt(sbi, opt)  \
+	do { (sbi)->s_mount_opt |= NILFS_MOUNT_##opt; } while (0)
+#define nilfs_test_opt(sbi, opt)   ((sbi)->s_mount_opt & NILFS_MOUNT_##opt)
+#define nilfs_write_opt(sbi, mask, opt)					\
+	do { (sbi)->s_mount_opt =					\
+		(((sbi)->s_mount_opt & ~NILFS_MOUNT_##mask) |		\
+		 NILFS_MOUNT_##opt);					\
+	} while (0)
+
+#endif /* _NILFS_SB */
diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
new file mode 100644
index 00000000000..1e68821b4a9
--- /dev/null
+++ b/fs/nilfs2/segbuf.c
@@ -0,0 +1,439 @@
+/*
+ * segbuf.c - NILFS segment buffer
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/crc32.h>
+#include "page.h"
+#include "segbuf.h"
+#include "seglist.h"
+
+
+static struct kmem_cache *nilfs_segbuf_cachep;
+
+static void nilfs_segbuf_init_once(void *obj)
+{
+	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
+}
+
+int __init nilfs_init_segbuf_cache(void)
+{
+	nilfs_segbuf_cachep =
+		kmem_cache_create("nilfs2_segbuf_cache",
+				  sizeof(struct nilfs_segment_buffer),
+				  0, SLAB_RECLAIM_ACCOUNT,
+				  nilfs_segbuf_init_once);
+
+	return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
+}
+
+void nilfs_destroy_segbuf_cache(void)
+{
+	kmem_cache_destroy(nilfs_segbuf_cachep);
+}
+
+struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
+{
+	struct nilfs_segment_buffer *segbuf;
+
+	segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
+	if (unlikely(!segbuf))
+		return NULL;
+
+	segbuf->sb_super = sb;
+	INIT_LIST_HEAD(&segbuf->sb_list);
+	INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
+	INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
+	return segbuf;
+}
+
+void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
+{
+	kmem_cache_free(nilfs_segbuf_cachep, segbuf);
+}
+
+void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
+		     unsigned long offset, struct the_nilfs *nilfs)
+{
+	segbuf->sb_segnum = segnum;
+	nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
+				&segbuf->sb_fseg_end);
+
+	segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
+	segbuf->sb_rest_blocks =
+		segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
+}
+
+void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
+				  __u64 nextnum, struct the_nilfs *nilfs)
+{
+	segbuf->sb_nextnum = nextnum;
+	segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
+}
+
+int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
+{
+	struct buffer_head *bh;
+
+	bh = sb_getblk(segbuf->sb_super,
+		       segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	nilfs_segbuf_add_segsum_buffer(segbuf, bh);
+	return 0;
+}
+
+int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
+				struct buffer_head **bhp)
+{
+	struct buffer_head *bh;
+
+	bh = sb_getblk(segbuf->sb_super,
+		       segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
+	if (unlikely(!bh))
+		return -ENOMEM;
+
+	nilfs_segbuf_add_payload_buffer(segbuf, bh);
+	*bhp = bh;
+	return 0;
+}
+
+int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
+		       time_t ctime)
+{
+	int err;
+
+	segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
+	err = nilfs_segbuf_extend_segsum(segbuf);
+	if (unlikely(err))
+		return err;
+
+	segbuf->sb_sum.flags = flags;
+	segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
+	segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
+	segbuf->sb_sum.ctime = ctime;
+
+	segbuf->sb_io_error = 0;
+	return 0;
+}
+
+/*
+ * Setup segument summary
+ */
+void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
+{
+	struct nilfs_segment_summary *raw_sum;
+	struct buffer_head *bh_sum;
+
+	bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
+			    struct buffer_head, b_assoc_buffers);
+	raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
+
+	raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
+	raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
+	raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
+	raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
+	raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
+	raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
+	raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
+	raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
+	raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
+	raw_sum->ss_pad      = 0;
+}
+
+/*
+ * CRC calculation routines
+ */
+void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
+				     u32 seed)
+{
+	struct buffer_head *bh;
+	struct nilfs_segment_summary *raw_sum;
+	unsigned long size, bytes = segbuf->sb_sum.sumbytes;
+	u32 crc;
+
+	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
+			b_assoc_buffers);
+
+	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
+	size = min_t(unsigned long, bytes, bh->b_size);
+	crc = crc32_le(seed,
+		       (unsigned char *)raw_sum +
+		       sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
+		       size - (sizeof(raw_sum->ss_datasum) +
+			       sizeof(raw_sum->ss_sumsum)));
+
+	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
+				     b_assoc_buffers) {
+		bytes -= size;
+		size = min_t(unsigned long, bytes, bh->b_size);
+		crc = crc32_le(crc, bh->b_data, size);
+	}
+	raw_sum->ss_sumsum = cpu_to_le32(crc);
+}
+
+void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
+				   u32 seed)
+{
+	struct buffer_head *bh;
+	struct nilfs_segment_summary *raw_sum;
+	void *kaddr;
+	u32 crc;
+
+	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
+			b_assoc_buffers);
+	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
+	crc = crc32_le(seed,
+		       (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
+		       bh->b_size - sizeof(raw_sum->ss_datasum));
+
+	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
+				     b_assoc_buffers) {
+		crc = crc32_le(crc, bh->b_data, bh->b_size);
+	}
+	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
+		kaddr = kmap_atomic(bh->b_page, KM_USER0);
+		crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+	raw_sum->ss_datasum = cpu_to_le32(crc);
+}
+
+void nilfs_release_buffers(struct list_head *list)
+{
+	struct buffer_head *bh, *n;
+
+	list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
+		list_del_init(&bh->b_assoc_buffers);
+		if (buffer_nilfs_allocated(bh)) {
+			struct page *clone_page = bh->b_page;
+
+			/* remove clone page */
+			brelse(bh);
+			page_cache_release(clone_page); /* for each bh */
+			if (page_count(clone_page) <= 2) {
+				lock_page(clone_page);
+				nilfs_free_private_page(clone_page);
+			}
+			continue;
+		}
+		brelse(bh);
+	}
+}
+
+/*
+ * BIO operations
+ */
+static void nilfs_end_bio_write(struct bio *bio, int err)
+{
+	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct nilfs_write_info *wi = bio->bi_private;
+
+	if (err == -EOPNOTSUPP) {
+		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+		bio_put(bio);
+		/* to be detected by submit_seg_bio() */
+	}
+
+	if (!uptodate)
+		atomic_inc(&wi->err);
+
+	bio_put(bio);
+	complete(&wi->bio_event);
+}
+
+static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
+{
+	struct bio *bio = wi->bio;
+	int err;
+
+	if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
+		wait_for_completion(&wi->bio_event);
+		wi->nbio--;
+		if (unlikely(atomic_read(&wi->err))) {
+			bio_put(bio);
+			err = -EIO;
+			goto failed;
+		}
+	}
+
+	bio->bi_end_io = nilfs_end_bio_write;
+	bio->bi_private = wi;
+	bio_get(bio);
+	submit_bio(mode, bio);
+	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
+		bio_put(bio);
+		err = -EOPNOTSUPP;
+		goto failed;
+	}
+	wi->nbio++;
+	bio_put(bio);
+
+	wi->bio = NULL;
+	wi->rest_blocks -= wi->end - wi->start;
+	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
+	wi->start = wi->end;
+	return 0;
+
+ failed:
+	wi->bio = NULL;
+	return err;
+}
+
+/**
+ * nilfs_alloc_seg_bio - allocate a bio for writing segment.
+ * @sb: super block
+ * @start: beginning disk block number of this BIO.
+ * @nr_vecs: request size of page vector.
+ *
+ * alloc_seg_bio() allocates a new BIO structure and initialize it.
+ *
+ * Return Value: On success, pointer to the struct bio is returned.
+ * On error, NULL is returned.
+ */
+static struct bio *nilfs_alloc_seg_bio(struct super_block *sb, sector_t start,
+				       int nr_vecs)
+{
+	struct bio *bio;
+
+	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+	if (bio == NULL) {
+		while (!bio && (nr_vecs >>= 1))
+			bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+	}
+	if (likely(bio)) {
+		bio->bi_bdev = sb->s_bdev;
+		bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
+	}
+	return bio;
+}
+
+void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
+				struct nilfs_write_info *wi)
+{
+	wi->bio = NULL;
+	wi->rest_blocks = segbuf->sb_sum.nblocks;
+	wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
+	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
+	wi->start = wi->end = 0;
+	wi->nbio = 0;
+	wi->blocknr = segbuf->sb_pseg_start;
+
+	atomic_set(&wi->err, 0);
+	init_completion(&wi->bio_event);
+}
+
+static int nilfs_submit_bh(struct nilfs_write_info *wi, struct buffer_head *bh,
+			   int mode)
+{
+	int len, err;
+
+	BUG_ON(wi->nr_vecs <= 0);
+ repeat:
+	if (!wi->bio) {
+		wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
+					      wi->nr_vecs);
+		if (unlikely(!wi->bio))
+			return -ENOMEM;
+	}
+
+	len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
+	if (len == bh->b_size) {
+		wi->end++;
+		return 0;
+	}
+	/* bio is FULL */
+	err = nilfs_submit_seg_bio(wi, mode);
+	/* never submit current bh */
+	if (likely(!err))
+		goto repeat;
+	return err;
+}
+
+int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
+		       struct nilfs_write_info *wi)
+{
+	struct buffer_head *bh;
+	int res, rw = WRITE;
+
+	list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
+		res = nilfs_submit_bh(wi, bh, rw);
+		if (unlikely(res))
+			goto failed_bio;
+	}
+
+	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
+		res = nilfs_submit_bh(wi, bh, rw);
+		if (unlikely(res))
+			goto failed_bio;
+	}
+
+	if (wi->bio) {
+		/*
+		 * Last BIO is always sent through the following
+		 * submission.
+		 */
+		rw |= (1 << BIO_RW_SYNCIO);
+		res = nilfs_submit_seg_bio(wi, rw);
+		if (unlikely(res))
+			goto failed_bio;
+	}
+
+	res = 0;
+ out:
+	return res;
+
+ failed_bio:
+	atomic_inc(&wi->err);
+	goto out;
+}
+
+/**
+ * nilfs_segbuf_wait - wait for completion of requested BIOs
+ * @wi: nilfs_write_info
+ *
+ * Return Value: On Success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error
+ */
+int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
+		      struct nilfs_write_info *wi)
+{
+	int err = 0;
+
+	if (!wi->nbio)
+		return 0;
+
+	do {
+		wait_for_completion(&wi->bio_event);
+	} while (--wi->nbio > 0);
+
+	if (unlikely(atomic_read(&wi->err) > 0)) {
+		printk(KERN_ERR "NILFS: IO error writing segment\n");
+		err = -EIO;
+		segbuf->sb_io_error = 1;
+	}
+	return err;
+}
diff --git a/fs/nilfs2/segbuf.h b/fs/nilfs2/segbuf.h
new file mode 100644
index 00000000000..0c3076f4e59
--- /dev/null
+++ b/fs/nilfs2/segbuf.h
@@ -0,0 +1,201 @@
+/*
+ * segbuf.h - NILFS Segment buffer prototypes and definitions
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+#ifndef _NILFS_SEGBUF_H
+#define _NILFS_SEGBUF_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/bio.h>
+#include <linux/completion.h>
+#include <linux/backing-dev.h>
+
+/**
+ * struct nilfs_segsum_info - On-memory segment summary
+ * @flags: Flags
+ * @nfinfo: Number of file information structures
+ * @nblocks: Number of blocks included in the partial segment
+ * @nsumblk: Number of summary blocks
+ * @sumbytes: Byte count of segment summary
+ * @nfileblk: Total number of file blocks
+ * @seg_seq: Segment sequence number
+ * @ctime: Creation time
+ * @next: Block number of the next full segment
+ */
+struct nilfs_segsum_info {
+	unsigned int		flags;
+	unsigned long		nfinfo;
+	unsigned long		nblocks;
+	unsigned long		nsumblk;
+	unsigned long		sumbytes;
+	unsigned long		nfileblk;
+	u64			seg_seq;
+	time_t			ctime;
+	sector_t		next;
+};
+
+/* macro for the flags */
+#define NILFS_SEG_HAS_SR(sum)    ((sum)->flags & NILFS_SS_SR)
+#define NILFS_SEG_LOGBGN(sum)    ((sum)->flags & NILFS_SS_LOGBGN)
+#define NILFS_SEG_LOGEND(sum)    ((sum)->flags & NILFS_SS_LOGEND)
+#define NILFS_SEG_DSYNC(sum)     ((sum)->flags & NILFS_SS_SYNDT)
+#define NILFS_SEG_SIMPLEX(sum) \
+	(((sum)->flags & (NILFS_SS_LOGBGN | NILFS_SS_LOGEND)) == \
+	 (NILFS_SS_LOGBGN | NILFS_SS_LOGEND))
+
+#define NILFS_SEG_EMPTY(sum)	((sum)->nblocks == (sum)->nsumblk)
+
+/**
+ * struct nilfs_segment_buffer - Segment buffer
+ * @sb_super: back pointer to a superblock struct
+ * @sb_list: List head to chain this structure
+ * @sb_sum: On-memory segment summary
+ * @sb_segnum: Index number of the full segment
+ * @sb_nextnum: Index number of the next full segment
+ * @sb_fseg_start: Start block number of the full segment
+ * @sb_fseg_end: End block number of the full segment
+ * @sb_pseg_start: Disk block number of partial segment
+ * @sb_rest_blocks: Number of residual blocks in the current segment
+ * @sb_segsum_buffers: List of buffers for segment summaries
+ * @sb_payload_buffers: List of buffers for segment payload
+ * @sb_io_error: I/O error status
+ */
+struct nilfs_segment_buffer {
+	struct super_block     *sb_super;
+	struct list_head	sb_list;
+
+	/* Segment information */
+	struct nilfs_segsum_info sb_sum;
+	__u64			sb_segnum;
+	__u64			sb_nextnum;
+	sector_t		sb_fseg_start, sb_fseg_end;
+	sector_t		sb_pseg_start;
+	unsigned		sb_rest_blocks;
+
+	/* Buffers */
+	struct list_head	sb_segsum_buffers;
+	struct list_head	sb_payload_buffers; /* including super root */
+
+	/* io status */
+	int			sb_io_error;
+};
+
+#define NILFS_LIST_SEGBUF(head)  \
+	list_entry((head), struct nilfs_segment_buffer, sb_list)
+#define NILFS_NEXT_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.next)
+#define NILFS_PREV_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.prev)
+#define NILFS_LAST_SEGBUF(head)    NILFS_LIST_SEGBUF((head)->prev)
+#define NILFS_FIRST_SEGBUF(head)   NILFS_LIST_SEGBUF((head)->next)
+#define NILFS_SEGBUF_IS_LAST(segbuf, head)  ((segbuf)->sb_list.next == (head))
+
+#define nilfs_for_each_segbuf_before(s, t, h) \
+	for ((s) = NILFS_FIRST_SEGBUF(h); (s) != (t); \
+	     (s) = NILFS_NEXT_SEGBUF(s))
+
+#define NILFS_SEGBUF_FIRST_BH(head)  \
+	(list_entry((head)->next, struct buffer_head, b_assoc_buffers))
+#define NILFS_SEGBUF_NEXT_BH(bh)  \
+	(list_entry((bh)->b_assoc_buffers.next, struct buffer_head, \
+		    b_assoc_buffers))
+#define NILFS_SEGBUF_BH_IS_LAST(bh, head)  ((bh)->b_assoc_buffers.next == head)
+
+
+int __init nilfs_init_segbuf_cache(void);
+void nilfs_destroy_segbuf_cache(void);
+struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *);
+void nilfs_segbuf_free(struct nilfs_segment_buffer *);
+void nilfs_segbuf_map(struct nilfs_segment_buffer *, __u64, unsigned long,
+		      struct the_nilfs *);
+void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *, __u64,
+				  struct the_nilfs *);
+int nilfs_segbuf_reset(struct nilfs_segment_buffer *, unsigned, time_t);
+int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *);
+int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *,
+				struct buffer_head **);
+void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *);
+void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *, u32);
+void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *, u32);
+
+static inline void
+nilfs_segbuf_add_segsum_buffer(struct nilfs_segment_buffer *segbuf,
+			       struct buffer_head *bh)
+{
+	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_segsum_buffers);
+	segbuf->sb_sum.nblocks++;
+	segbuf->sb_sum.nsumblk++;
+}
+
+static inline void
+nilfs_segbuf_add_payload_buffer(struct nilfs_segment_buffer *segbuf,
+				struct buffer_head *bh)
+{
+	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_payload_buffers);
+	segbuf->sb_sum.nblocks++;
+}
+
+static inline void
+nilfs_segbuf_add_file_buffer(struct nilfs_segment_buffer *segbuf,
+			     struct buffer_head *bh)
+{
+	get_bh(bh);
+	nilfs_segbuf_add_payload_buffer(segbuf, bh);
+	segbuf->sb_sum.nfileblk++;
+}
+
+void nilfs_release_buffers(struct list_head *);
+
+static inline void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
+{
+	nilfs_release_buffers(&segbuf->sb_segsum_buffers);
+	nilfs_release_buffers(&segbuf->sb_payload_buffers);
+}
+
+struct nilfs_write_info {
+	struct bio	       *bio;
+	int 			start, end; /* The region to be submitted */
+	int			rest_blocks;
+	int			max_pages;
+	int			nr_vecs;
+	sector_t		blocknr;
+
+	int			nbio;
+	atomic_t		err;
+	struct completion	bio_event;
+				/* completion event of segment write */
+
+	/*
+	 * The following fields must be set explicitly
+	 */
+	struct super_block     *sb;
+	struct backing_dev_info *bdi; /* backing dev info */
+	struct buffer_head     *bh_sr;
+};
+
+
+void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *,
+				struct nilfs_write_info *);
+int nilfs_segbuf_write(struct nilfs_segment_buffer *,
+		       struct nilfs_write_info *);
+int nilfs_segbuf_wait(struct nilfs_segment_buffer *,
+		      struct nilfs_write_info *);
+
+#endif /* _NILFS_SEGBUF_H */
diff --git a/fs/nilfs2/seglist.h b/fs/nilfs2/seglist.h
new file mode 100644
index 00000000000..d39df9144e9
--- /dev/null
+++ b/fs/nilfs2/seglist.h
@@ -0,0 +1,85 @@
+/*
+ * seglist.h - expediential structure and routines to handle list of segments
+ *             (would be removed in a future release)
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+#ifndef _NILFS_SEGLIST_H
+#define _NILFS_SEGLIST_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+#include "sufile.h"
+
+struct nilfs_segment_entry {
+	__u64			segnum;
+
+#define NILFS_SLH_FREED		0x0001	/* The segment was freed provisonally.
+					   It must be cancelled if
+					   construction aborted */
+
+	unsigned		flags;
+	struct list_head	list;
+	struct buffer_head     *bh_su;
+	struct nilfs_segment_usage *raw_su;
+};
+
+
+void nilfs_dispose_segment_list(struct list_head *);
+
+static inline struct nilfs_segment_entry *
+nilfs_alloc_segment_entry(__u64 segnum)
+{
+	struct nilfs_segment_entry *ent = kmalloc(sizeof(*ent), GFP_NOFS);
+
+	if (likely(ent)) {
+		ent->segnum = segnum;
+		ent->flags = 0;
+		ent->bh_su = NULL;
+		ent->raw_su = NULL;
+		INIT_LIST_HEAD(&ent->list);
+	}
+	return ent;
+}
+
+static inline int nilfs_open_segment_entry(struct nilfs_segment_entry *ent,
+					   struct inode *sufile)
+{
+	return nilfs_sufile_get_segment_usage(sufile, ent->segnum,
+					      &ent->raw_su, &ent->bh_su);
+}
+
+static inline void nilfs_close_segment_entry(struct nilfs_segment_entry *ent,
+					     struct inode *sufile)
+{
+	if (!ent->bh_su)
+		return;
+	nilfs_sufile_put_segment_usage(sufile, ent->segnum, ent->bh_su);
+	ent->bh_su = NULL;
+	ent->raw_su = NULL;
+}
+
+static inline void nilfs_free_segment_entry(struct nilfs_segment_entry *ent)
+{
+	kfree(ent);
+}
+
+#endif /* _NILFS_SEGLIST_H */
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
new file mode 100644
index 00000000000..fb70ec3be20
--- /dev/null
+++ b/fs/nilfs2/segment.c
@@ -0,0 +1,2977 @@
+/*
+ * segment.c - NILFS segment constructor.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/bio.h>
+#include <linux/completion.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/crc32.h>
+#include <linux/pagevec.h>
+#include "nilfs.h"
+#include "btnode.h"
+#include "page.h"
+#include "segment.h"
+#include "sufile.h"
+#include "cpfile.h"
+#include "ifile.h"
+#include "seglist.h"
+#include "segbuf.h"
+
+
+/*
+ * Segment constructor
+ */
+#define SC_N_INODEVEC	16   /* Size of locally allocated inode vector */
+
+#define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
+				appended in collection retry loop */
+
+/* Construction mode */
+enum {
+	SC_LSEG_SR = 1,	/* Make a logical segment having a super root */
+	SC_LSEG_DSYNC,	/* Flush data blocks of a given file and make
+			   a logical segment without a super root */
+	SC_FLUSH_FILE,	/* Flush data files, leads to segment writes without
+			   creating a checkpoint */
+	SC_FLUSH_DAT,	/* Flush DAT file. This also creates segments without
+			   a checkpoint */
+};
+
+/* Stage numbers of dirty block collection */
+enum {
+	NILFS_ST_INIT = 0,
+	NILFS_ST_GC,		/* Collecting dirty blocks for GC */
+	NILFS_ST_FILE,
+	NILFS_ST_IFILE,
+	NILFS_ST_CPFILE,
+	NILFS_ST_SUFILE,
+	NILFS_ST_DAT,
+	NILFS_ST_SR,		/* Super root */
+	NILFS_ST_DSYNC,		/* Data sync blocks */
+	NILFS_ST_DONE,
+};
+
+/* State flags of collection */
+#define NILFS_CF_NODE		0x0001	/* Collecting node blocks */
+#define NILFS_CF_IFILE_STARTED	0x0002	/* IFILE stage has started */
+#define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED)
+
+/* Operations depending on the construction mode and file type */
+struct nilfs_sc_operations {
+	int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
+			    struct inode *);
+	int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
+			    struct inode *);
+	int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
+			    struct inode *);
+	void (*write_data_binfo)(struct nilfs_sc_info *,
+				 struct nilfs_segsum_pointer *,
+				 union nilfs_binfo *);
+	void (*write_node_binfo)(struct nilfs_sc_info *,
+				 struct nilfs_segsum_pointer *,
+				 union nilfs_binfo *);
+};
+
+/*
+ * Other definitions
+ */
+static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
+static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
+static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
+static void nilfs_dispose_list(struct nilfs_sb_info *, struct list_head *,
+			       int);
+
+#define nilfs_cnt32_gt(a, b)   \
+	(typecheck(__u32, a) && typecheck(__u32, b) && \
+	 ((__s32)(b) - (__s32)(a) < 0))
+#define nilfs_cnt32_ge(a, b)   \
+	(typecheck(__u32, a) && typecheck(__u32, b) && \
+	 ((__s32)(a) - (__s32)(b) >= 0))
+#define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
+#define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
+
+/*
+ * Transaction
+ */
+static struct kmem_cache *nilfs_transaction_cachep;
+
+/**
+ * nilfs_init_transaction_cache - create a cache for nilfs_transaction_info
+ *
+ * nilfs_init_transaction_cache() creates a slab cache for the struct
+ * nilfs_transaction_info.
+ *
+ * Return Value: On success, it returns 0. On error, one of the following
+ * negative error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ */
+int nilfs_init_transaction_cache(void)
+{
+	nilfs_transaction_cachep =
+		kmem_cache_create("nilfs2_transaction_cache",
+				  sizeof(struct nilfs_transaction_info),
+				  0, SLAB_RECLAIM_ACCOUNT, NULL);
+	return (nilfs_transaction_cachep == NULL) ? -ENOMEM : 0;
+}
+
+/**
+ * nilfs_detroy_transaction_cache - destroy the cache for transaction info
+ *
+ * nilfs_destroy_transaction_cache() frees the slab cache for the struct
+ * nilfs_transaction_info.
+ */
+void nilfs_destroy_transaction_cache(void)
+{
+	kmem_cache_destroy(nilfs_transaction_cachep);
+}
+
+static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
+{
+	struct nilfs_transaction_info *cur_ti = current->journal_info;
+	void *save = NULL;
+
+	if (cur_ti) {
+		if (cur_ti->ti_magic == NILFS_TI_MAGIC)
+			return ++cur_ti->ti_count;
+		else {
+			/*
+			 * If journal_info field is occupied by other FS,
+			 * it is saved and will be restored on
+			 * nilfs_transaction_commit().
+			 */
+			printk(KERN_WARNING
+			       "NILFS warning: journal info from a different "
+			       "FS\n");
+			save = current->journal_info;
+		}
+	}
+	if (!ti) {
+		ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
+		if (!ti)
+			return -ENOMEM;
+		ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
+	} else {
+		ti->ti_flags = 0;
+	}
+	ti->ti_count = 0;
+	ti->ti_save = save;
+	ti->ti_magic = NILFS_TI_MAGIC;
+	current->journal_info = ti;
+	return 0;
+}
+
+/**
+ * nilfs_transaction_begin - start indivisible file operations.
+ * @sb: super block
+ * @ti: nilfs_transaction_info
+ * @vacancy_check: flags for vacancy rate checks
+ *
+ * nilfs_transaction_begin() acquires a reader/writer semaphore, called
+ * the segment semaphore, to make a segment construction and write tasks
+ * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
+ * The region enclosed by these two functions can be nested.  To avoid a
+ * deadlock, the semaphore is only acquired or released in the outermost call.
+ *
+ * This function allocates a nilfs_transaction_info struct to keep context
+ * information on it.  It is initialized and hooked onto the current task in
+ * the outermost call.  If a pre-allocated struct is given to @ti, it is used
+ * instead; othewise a new struct is assigned from a slab.
+ *
+ * When @vacancy_check flag is set, this function will check the amount of
+ * free space, and will wait for the GC to reclaim disk space if low capacity.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-ENOSPC - No space left on device
+ */
+int nilfs_transaction_begin(struct super_block *sb,
+			    struct nilfs_transaction_info *ti,
+			    int vacancy_check)
+{
+	struct nilfs_sb_info *sbi;
+	struct the_nilfs *nilfs;
+	int ret = nilfs_prepare_segment_lock(ti);
+
+	if (unlikely(ret < 0))
+		return ret;
+	if (ret > 0)
+		return 0;
+
+	sbi = NILFS_SB(sb);
+	nilfs = sbi->s_nilfs;
+	down_read(&nilfs->ns_segctor_sem);
+	if (vacancy_check && nilfs_near_disk_full(nilfs)) {
+		up_read(&nilfs->ns_segctor_sem);
+		ret = -ENOSPC;
+		goto failed;
+	}
+	return 0;
+
+ failed:
+	ti = current->journal_info;
+	current->journal_info = ti->ti_save;
+	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
+		kmem_cache_free(nilfs_transaction_cachep, ti);
+	return ret;
+}
+
+/**
+ * nilfs_transaction_commit - commit indivisible file operations.
+ * @sb: super block
+ *
+ * nilfs_transaction_commit() releases the read semaphore which is
+ * acquired by nilfs_transaction_begin(). This is only performed
+ * in outermost call of this function.  If a commit flag is set,
+ * nilfs_transaction_commit() sets a timer to start the segment
+ * constructor.  If a sync flag is set, it starts construction
+ * directly.
+ */
+int nilfs_transaction_commit(struct super_block *sb)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+	struct nilfs_sb_info *sbi;
+	struct nilfs_sc_info *sci;
+	int err = 0;
+
+	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
+	ti->ti_flags |= NILFS_TI_COMMIT;
+	if (ti->ti_count > 0) {
+		ti->ti_count--;
+		return 0;
+	}
+	sbi = NILFS_SB(sb);
+	sci = NILFS_SC(sbi);
+	if (sci != NULL) {
+		if (ti->ti_flags & NILFS_TI_COMMIT)
+			nilfs_segctor_start_timer(sci);
+		if (atomic_read(&sbi->s_nilfs->ns_ndirtyblks) >
+		    sci->sc_watermark)
+			nilfs_segctor_do_flush(sci, 0);
+	}
+	up_read(&sbi->s_nilfs->ns_segctor_sem);
+	current->journal_info = ti->ti_save;
+
+	if (ti->ti_flags & NILFS_TI_SYNC)
+		err = nilfs_construct_segment(sb);
+	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
+		kmem_cache_free(nilfs_transaction_cachep, ti);
+	return err;
+}
+
+void nilfs_transaction_abort(struct super_block *sb)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+
+	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
+	if (ti->ti_count > 0) {
+		ti->ti_count--;
+		return;
+	}
+	up_read(&NILFS_SB(sb)->s_nilfs->ns_segctor_sem);
+
+	current->journal_info = ti->ti_save;
+	if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
+		kmem_cache_free(nilfs_transaction_cachep, ti);
+}
+
+void nilfs_relax_pressure_in_lock(struct super_block *sb)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_sc_info *sci = NILFS_SC(sbi);
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+
+	if (!sci || !sci->sc_flush_request)
+		return;
+
+	set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
+	up_read(&nilfs->ns_segctor_sem);
+
+	down_write(&nilfs->ns_segctor_sem);
+	if (sci->sc_flush_request &&
+	    test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
+		struct nilfs_transaction_info *ti = current->journal_info;
+
+		ti->ti_flags |= NILFS_TI_WRITER;
+		nilfs_segctor_do_immediate_flush(sci);
+		ti->ti_flags &= ~NILFS_TI_WRITER;
+	}
+	downgrade_write(&nilfs->ns_segctor_sem);
+}
+
+static void nilfs_transaction_lock(struct nilfs_sb_info *sbi,
+				   struct nilfs_transaction_info *ti,
+				   int gcflag)
+{
+	struct nilfs_transaction_info *cur_ti = current->journal_info;
+
+	WARN_ON(cur_ti);
+	ti->ti_flags = NILFS_TI_WRITER;
+	ti->ti_count = 0;
+	ti->ti_save = cur_ti;
+	ti->ti_magic = NILFS_TI_MAGIC;
+	INIT_LIST_HEAD(&ti->ti_garbage);
+	current->journal_info = ti;
+
+	for (;;) {
+		down_write(&sbi->s_nilfs->ns_segctor_sem);
+		if (!test_bit(NILFS_SC_PRIOR_FLUSH, &NILFS_SC(sbi)->sc_flags))
+			break;
+
+		nilfs_segctor_do_immediate_flush(NILFS_SC(sbi));
+
+		up_write(&sbi->s_nilfs->ns_segctor_sem);
+		yield();
+	}
+	if (gcflag)
+		ti->ti_flags |= NILFS_TI_GC;
+}
+
+static void nilfs_transaction_unlock(struct nilfs_sb_info *sbi)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+
+	BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
+	BUG_ON(ti->ti_count > 0);
+
+	up_write(&sbi->s_nilfs->ns_segctor_sem);
+	current->journal_info = ti->ti_save;
+	if (!list_empty(&ti->ti_garbage))
+		nilfs_dispose_list(sbi, &ti->ti_garbage, 0);
+}
+
+static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
+					    struct nilfs_segsum_pointer *ssp,
+					    unsigned bytes)
+{
+	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
+	unsigned blocksize = sci->sc_super->s_blocksize;
+	void *p;
+
+	if (unlikely(ssp->offset + bytes > blocksize)) {
+		ssp->offset = 0;
+		BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
+					       &segbuf->sb_segsum_buffers));
+		ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
+	}
+	p = ssp->bh->b_data + ssp->offset;
+	ssp->offset += bytes;
+	return p;
+}
+
+/**
+ * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
+ * @sci: nilfs_sc_info
+ */
+static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
+	struct buffer_head *sumbh;
+	unsigned sumbytes;
+	unsigned flags = 0;
+	int err;
+
+	if (nilfs_doing_gc())
+		flags = NILFS_SS_GC;
+	err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime);
+	if (unlikely(err))
+		return err;
+
+	sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
+	sumbytes = segbuf->sb_sum.sumbytes;
+	sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
+	sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
+	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
+	return 0;
+}
+
+static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
+{
+	sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
+	if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
+		return -E2BIG; /* The current segment is filled up
+				  (internal code) */
+	sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
+	return nilfs_segctor_reset_segment_buffer(sci);
+}
+
+static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
+	int err;
+
+	if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
+		err = nilfs_segctor_feed_segment(sci);
+		if (err)
+			return err;
+		segbuf = sci->sc_curseg;
+	}
+	err = nilfs_segbuf_extend_payload(segbuf, &sci->sc_super_root);
+	if (likely(!err))
+		segbuf->sb_sum.flags |= NILFS_SS_SR;
+	return err;
+}
+
+/*
+ * Functions for making segment summary and payloads
+ */
+static int nilfs_segctor_segsum_block_required(
+	struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
+	unsigned binfo_size)
+{
+	unsigned blocksize = sci->sc_super->s_blocksize;
+	/* Size of finfo and binfo is enough small against blocksize */
+
+	return ssp->offset + binfo_size +
+		(!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
+		blocksize;
+}
+
+static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
+				      struct inode *inode)
+{
+	sci->sc_curseg->sb_sum.nfinfo++;
+	sci->sc_binfo_ptr = sci->sc_finfo_ptr;
+	nilfs_segctor_map_segsum_entry(
+		sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
+
+	if (inode->i_sb && !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
+		set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
+	/* skip finfo */
+}
+
+static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
+				    struct inode *inode)
+{
+	struct nilfs_finfo *finfo;
+	struct nilfs_inode_info *ii;
+	struct nilfs_segment_buffer *segbuf;
+
+	if (sci->sc_blk_cnt == 0)
+		return;
+
+	ii = NILFS_I(inode);
+	finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
+						 sizeof(*finfo));
+	finfo->fi_ino = cpu_to_le64(inode->i_ino);
+	finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
+	finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
+	finfo->fi_cno = cpu_to_le64(ii->i_cno);
+
+	segbuf = sci->sc_curseg;
+	segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
+		sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
+	sci->sc_finfo_ptr = sci->sc_binfo_ptr;
+	sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
+}
+
+static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
+					struct buffer_head *bh,
+					struct inode *inode,
+					unsigned binfo_size)
+{
+	struct nilfs_segment_buffer *segbuf;
+	int required, err = 0;
+
+ retry:
+	segbuf = sci->sc_curseg;
+	required = nilfs_segctor_segsum_block_required(
+		sci, &sci->sc_binfo_ptr, binfo_size);
+	if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
+		nilfs_segctor_end_finfo(sci, inode);
+		err = nilfs_segctor_feed_segment(sci);
+		if (err)
+			return err;
+		goto retry;
+	}
+	if (unlikely(required)) {
+		err = nilfs_segbuf_extend_segsum(segbuf);
+		if (unlikely(err))
+			goto failed;
+	}
+	if (sci->sc_blk_cnt == 0)
+		nilfs_segctor_begin_finfo(sci, inode);
+
+	nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
+	/* Substitution to vblocknr is delayed until update_blocknr() */
+	nilfs_segbuf_add_file_buffer(segbuf, bh);
+	sci->sc_blk_cnt++;
+ failed:
+	return err;
+}
+
+static int nilfs_handle_bmap_error(int err, const char *fname,
+				   struct inode *inode, struct super_block *sb)
+{
+	if (err == -EINVAL) {
+		nilfs_error(sb, fname, "broken bmap (inode=%lu)\n",
+			    inode->i_ino);
+		err = -EIO;
+	}
+	return err;
+}
+
+/*
+ * Callback functions that enumerate, mark, and collect dirty blocks
+ */
+static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
+				   struct buffer_head *bh, struct inode *inode)
+{
+	int err;
+
+	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
+	if (unlikely(err < 0))
+		return nilfs_handle_bmap_error(err, __func__, inode,
+					       sci->sc_super);
+
+	err = nilfs_segctor_add_file_block(sci, bh, inode,
+					   sizeof(struct nilfs_binfo_v));
+	if (!err)
+		sci->sc_datablk_cnt++;
+	return err;
+}
+
+static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
+				   struct buffer_head *bh,
+				   struct inode *inode)
+{
+	int err;
+
+	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
+	if (unlikely(err < 0))
+		return nilfs_handle_bmap_error(err, __func__, inode,
+					       sci->sc_super);
+	return 0;
+}
+
+static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
+				   struct buffer_head *bh,
+				   struct inode *inode)
+{
+	WARN_ON(!buffer_dirty(bh));
+	return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
+}
+
+static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
+					struct nilfs_segsum_pointer *ssp,
+					union nilfs_binfo *binfo)
+{
+	struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
+		sci, ssp, sizeof(*binfo_v));
+	*binfo_v = binfo->bi_v;
+}
+
+static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
+					struct nilfs_segsum_pointer *ssp,
+					union nilfs_binfo *binfo)
+{
+	__le64 *vblocknr = nilfs_segctor_map_segsum_entry(
+		sci, ssp, sizeof(*vblocknr));
+	*vblocknr = binfo->bi_v.bi_vblocknr;
+}
+
+struct nilfs_sc_operations nilfs_sc_file_ops = {
+	.collect_data = nilfs_collect_file_data,
+	.collect_node = nilfs_collect_file_node,
+	.collect_bmap = nilfs_collect_file_bmap,
+	.write_data_binfo = nilfs_write_file_data_binfo,
+	.write_node_binfo = nilfs_write_file_node_binfo,
+};
+
+static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
+				  struct buffer_head *bh, struct inode *inode)
+{
+	int err;
+
+	err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
+	if (unlikely(err < 0))
+		return nilfs_handle_bmap_error(err, __func__, inode,
+					       sci->sc_super);
+
+	err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
+	if (!err)
+		sci->sc_datablk_cnt++;
+	return err;
+}
+
+static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
+				  struct buffer_head *bh, struct inode *inode)
+{
+	WARN_ON(!buffer_dirty(bh));
+	return nilfs_segctor_add_file_block(sci, bh, inode,
+					    sizeof(struct nilfs_binfo_dat));
+}
+
+static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
+				       struct nilfs_segsum_pointer *ssp,
+				       union nilfs_binfo *binfo)
+{
+	__le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
+							  sizeof(*blkoff));
+	*blkoff = binfo->bi_dat.bi_blkoff;
+}
+
+static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
+				       struct nilfs_segsum_pointer *ssp,
+				       union nilfs_binfo *binfo)
+{
+	struct nilfs_binfo_dat *binfo_dat =
+		nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
+	*binfo_dat = binfo->bi_dat;
+}
+
+struct nilfs_sc_operations nilfs_sc_dat_ops = {
+	.collect_data = nilfs_collect_dat_data,
+	.collect_node = nilfs_collect_file_node,
+	.collect_bmap = nilfs_collect_dat_bmap,
+	.write_data_binfo = nilfs_write_dat_data_binfo,
+	.write_node_binfo = nilfs_write_dat_node_binfo,
+};
+
+struct nilfs_sc_operations nilfs_sc_dsync_ops = {
+	.collect_data = nilfs_collect_file_data,
+	.collect_node = NULL,
+	.collect_bmap = NULL,
+	.write_data_binfo = nilfs_write_file_data_binfo,
+	.write_node_binfo = NULL,
+};
+
+static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
+					      struct list_head *listp,
+					      size_t nlimit,
+					      loff_t start, loff_t end)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct pagevec pvec;
+	pgoff_t index = 0, last = ULONG_MAX;
+	size_t ndirties = 0;
+	int i;
+
+	if (unlikely(start != 0 || end != LLONG_MAX)) {
+		/*
+		 * A valid range is given for sync-ing data pages. The
+		 * range is rounded to per-page; extra dirty buffers
+		 * may be included if blocksize < pagesize.
+		 */
+		index = start >> PAGE_SHIFT;
+		last = end >> PAGE_SHIFT;
+	}
+	pagevec_init(&pvec, 0);
+ repeat:
+	if (unlikely(index > last) ||
+	    !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
+				min_t(pgoff_t, last - index,
+				      PAGEVEC_SIZE - 1) + 1))
+		return ndirties;
+
+	for (i = 0; i < pagevec_count(&pvec); i++) {
+		struct buffer_head *bh, *head;
+		struct page *page = pvec.pages[i];
+
+		if (unlikely(page->index > last))
+			break;
+
+		if (mapping->host) {
+			lock_page(page);
+			if (!page_has_buffers(page))
+				create_empty_buffers(page,
+						     1 << inode->i_blkbits, 0);
+			unlock_page(page);
+		}
+
+		bh = head = page_buffers(page);
+		do {
+			if (!buffer_dirty(bh))
+				continue;
+			get_bh(bh);
+			list_add_tail(&bh->b_assoc_buffers, listp);
+			ndirties++;
+			if (unlikely(ndirties >= nlimit)) {
+				pagevec_release(&pvec);
+				cond_resched();
+				return ndirties;
+			}
+		} while (bh = bh->b_this_page, bh != head);
+	}
+	pagevec_release(&pvec);
+	cond_resched();
+	goto repeat;
+}
+
+static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
+					    struct list_head *listp)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+	struct address_space *mapping = &ii->i_btnode_cache;
+	struct pagevec pvec;
+	struct buffer_head *bh, *head;
+	unsigned int i;
+	pgoff_t index = 0;
+
+	pagevec_init(&pvec, 0);
+
+	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
+				  PAGEVEC_SIZE)) {
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			bh = head = page_buffers(pvec.pages[i]);
+			do {
+				if (buffer_dirty(bh)) {
+					get_bh(bh);
+					list_add_tail(&bh->b_assoc_buffers,
+						      listp);
+				}
+				bh = bh->b_this_page;
+			} while (bh != head);
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+}
+
+static void nilfs_dispose_list(struct nilfs_sb_info *sbi,
+			       struct list_head *head, int force)
+{
+	struct nilfs_inode_info *ii, *n;
+	struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
+	unsigned nv = 0;
+
+	while (!list_empty(head)) {
+		spin_lock(&sbi->s_inode_lock);
+		list_for_each_entry_safe(ii, n, head, i_dirty) {
+			list_del_init(&ii->i_dirty);
+			if (force) {
+				if (unlikely(ii->i_bh)) {
+					brelse(ii->i_bh);
+					ii->i_bh = NULL;
+				}
+			} else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
+				set_bit(NILFS_I_QUEUED, &ii->i_state);
+				list_add_tail(&ii->i_dirty,
+					      &sbi->s_dirty_files);
+				continue;
+			}
+			ivec[nv++] = ii;
+			if (nv == SC_N_INODEVEC)
+				break;
+		}
+		spin_unlock(&sbi->s_inode_lock);
+
+		for (pii = ivec; nv > 0; pii++, nv--)
+			iput(&(*pii)->vfs_inode);
+	}
+}
+
+static int nilfs_test_metadata_dirty(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int ret = 0;
+
+	if (nilfs_mdt_fetch_dirty(sbi->s_ifile))
+		ret++;
+	if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
+		ret++;
+	if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
+		ret++;
+	if (ret || nilfs_doing_gc())
+		if (nilfs_mdt_fetch_dirty(nilfs_dat_inode(nilfs)))
+			ret++;
+	return ret;
+}
+
+static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
+{
+	return list_empty(&sci->sc_dirty_files) &&
+		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
+		list_empty(&sci->sc_cleaning_segments) &&
+		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
+}
+
+static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	int ret = 0;
+
+	if (nilfs_test_metadata_dirty(sbi))
+		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
+
+	spin_lock(&sbi->s_inode_lock);
+	if (list_empty(&sbi->s_dirty_files) && nilfs_segctor_clean(sci))
+		ret++;
+
+	spin_unlock(&sbi->s_inode_lock);
+	return ret;
+}
+
+static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+
+	nilfs_mdt_clear_dirty(sbi->s_ifile);
+	nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
+	nilfs_mdt_clear_dirty(nilfs->ns_sufile);
+	nilfs_mdt_clear_dirty(nilfs_dat_inode(nilfs));
+}
+
+static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
+{
+	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
+	struct buffer_head *bh_cp;
+	struct nilfs_checkpoint *raw_cp;
+	int err;
+
+	/* XXX: this interface will be changed */
+	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
+					  &raw_cp, &bh_cp);
+	if (likely(!err)) {
+		/* The following code is duplicated with cpfile.  But, it is
+		   needed to collect the checkpoint even if it was not newly
+		   created */
+		nilfs_mdt_mark_buffer_dirty(bh_cp);
+		nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
+		nilfs_cpfile_put_checkpoint(
+			nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
+	} else
+		WARN_ON(err == -EINVAL || err == -ENOENT);
+
+	return err;
+}
+
+static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct buffer_head *bh_cp;
+	struct nilfs_checkpoint *raw_cp;
+	int err;
+
+	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
+					  &raw_cp, &bh_cp);
+	if (unlikely(err)) {
+		WARN_ON(err == -EINVAL || err == -ENOENT);
+		goto failed_ibh;
+	}
+	raw_cp->cp_snapshot_list.ssl_next = 0;
+	raw_cp->cp_snapshot_list.ssl_prev = 0;
+	raw_cp->cp_inodes_count =
+		cpu_to_le64(atomic_read(&sbi->s_inodes_count));
+	raw_cp->cp_blocks_count =
+		cpu_to_le64(atomic_read(&sbi->s_blocks_count));
+	raw_cp->cp_nblk_inc =
+		cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
+	raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
+	raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
+
+	if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
+		nilfs_checkpoint_clear_minor(raw_cp);
+	else
+		nilfs_checkpoint_set_minor(raw_cp);
+
+	nilfs_write_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode, 1);
+	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
+	return 0;
+
+ failed_ibh:
+	return err;
+}
+
+static void nilfs_fill_in_file_bmap(struct inode *ifile,
+				    struct nilfs_inode_info *ii)
+
+{
+	struct buffer_head *ibh;
+	struct nilfs_inode *raw_inode;
+
+	if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
+		ibh = ii->i_bh;
+		BUG_ON(!ibh);
+		raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
+						  ibh);
+		nilfs_bmap_write(ii->i_bmap, raw_inode);
+		nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
+	}
+}
+
+static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci,
+					    struct inode *ifile)
+{
+	struct nilfs_inode_info *ii;
+
+	list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
+		nilfs_fill_in_file_bmap(ifile, ii);
+		set_bit(NILFS_I_COLLECTED, &ii->i_state);
+	}
+}
+
+/*
+ * CRC calculation routines
+ */
+static void nilfs_fill_in_super_root_crc(struct buffer_head *bh_sr, u32 seed)
+{
+	struct nilfs_super_root *raw_sr =
+		(struct nilfs_super_root *)bh_sr->b_data;
+	u32 crc;
+
+	crc = crc32_le(seed,
+		       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
+		       NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
+	raw_sr->sr_sum = cpu_to_le32(crc);
+}
+
+static void nilfs_segctor_fill_in_checksums(struct nilfs_sc_info *sci,
+					    u32 seed)
+{
+	struct nilfs_segment_buffer *segbuf;
+
+	if (sci->sc_super_root)
+		nilfs_fill_in_super_root_crc(sci->sc_super_root, seed);
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
+		nilfs_segbuf_fill_in_data_crc(segbuf, seed);
+	}
+}
+
+static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
+					     struct the_nilfs *nilfs)
+{
+	struct buffer_head *bh_sr = sci->sc_super_root;
+	struct nilfs_super_root *raw_sr =
+		(struct nilfs_super_root *)bh_sr->b_data;
+	unsigned isz = nilfs->ns_inode_size;
+
+	raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
+	raw_sr->sr_nongc_ctime
+		= cpu_to_le64(nilfs_doing_gc() ?
+			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
+	raw_sr->sr_flags = 0;
+
+	nilfs_mdt_write_inode_direct(
+		nilfs_dat_inode(nilfs), bh_sr, NILFS_SR_DAT_OFFSET(isz));
+	nilfs_mdt_write_inode_direct(
+		nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(isz));
+	nilfs_mdt_write_inode_direct(
+		nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(isz));
+}
+
+static void nilfs_redirty_inodes(struct list_head *head)
+{
+	struct nilfs_inode_info *ii;
+
+	list_for_each_entry(ii, head, i_dirty) {
+		if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
+			clear_bit(NILFS_I_COLLECTED, &ii->i_state);
+	}
+}
+
+static void nilfs_drop_collected_inodes(struct list_head *head)
+{
+	struct nilfs_inode_info *ii;
+
+	list_for_each_entry(ii, head, i_dirty) {
+		if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
+			continue;
+
+		clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
+		set_bit(NILFS_I_UPDATED, &ii->i_state);
+	}
+}
+
+static void nilfs_segctor_cancel_free_segments(struct nilfs_sc_info *sci,
+					       struct inode *sufile)
+
+{
+	struct list_head *head = &sci->sc_cleaning_segments;
+	struct nilfs_segment_entry *ent;
+	int err;
+
+	list_for_each_entry(ent, head, list) {
+		if (!(ent->flags & NILFS_SLH_FREED))
+			break;
+		err = nilfs_sufile_cancel_free(sufile, ent->segnum);
+		WARN_ON(err); /* do not happen */
+		ent->flags &= ~NILFS_SLH_FREED;
+	}
+}
+
+static int nilfs_segctor_prepare_free_segments(struct nilfs_sc_info *sci,
+					       struct inode *sufile)
+{
+	struct list_head *head = &sci->sc_cleaning_segments;
+	struct nilfs_segment_entry *ent;
+	int err;
+
+	list_for_each_entry(ent, head, list) {
+		err = nilfs_sufile_free(sufile, ent->segnum);
+		if (unlikely(err))
+			return err;
+		ent->flags |= NILFS_SLH_FREED;
+	}
+	return 0;
+}
+
+static void nilfs_segctor_commit_free_segments(struct nilfs_sc_info *sci)
+{
+	nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
+}
+
+static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
+				       struct inode *inode,
+				       struct list_head *listp,
+				       int (*collect)(struct nilfs_sc_info *,
+						      struct buffer_head *,
+						      struct inode *))
+{
+	struct buffer_head *bh, *n;
+	int err = 0;
+
+	if (collect) {
+		list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
+			list_del_init(&bh->b_assoc_buffers);
+			err = collect(sci, bh, inode);
+			brelse(bh);
+			if (unlikely(err))
+				goto dispose_buffers;
+		}
+		return 0;
+	}
+
+ dispose_buffers:
+	while (!list_empty(listp)) {
+		bh = list_entry(listp->next, struct buffer_head,
+				b_assoc_buffers);
+		list_del_init(&bh->b_assoc_buffers);
+		brelse(bh);
+	}
+	return err;
+}
+
+static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
+{
+	/* Remaining number of blocks within segment buffer */
+	return sci->sc_segbuf_nblocks -
+		(sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
+}
+
+static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
+				   struct inode *inode,
+				   struct nilfs_sc_operations *sc_ops)
+{
+	LIST_HEAD(data_buffers);
+	LIST_HEAD(node_buffers);
+	int err;
+
+	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
+		size_t n, rest = nilfs_segctor_buffer_rest(sci);
+
+		n = nilfs_lookup_dirty_data_buffers(
+			inode, &data_buffers, rest + 1, 0, LLONG_MAX);
+		if (n > rest) {
+			err = nilfs_segctor_apply_buffers(
+				sci, inode, &data_buffers,
+				sc_ops->collect_data);
+			BUG_ON(!err); /* always receive -E2BIG or true error */
+			goto break_or_fail;
+		}
+	}
+	nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
+
+	if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
+		err = nilfs_segctor_apply_buffers(
+			sci, inode, &data_buffers, sc_ops->collect_data);
+		if (unlikely(err)) {
+			/* dispose node list */
+			nilfs_segctor_apply_buffers(
+				sci, inode, &node_buffers, NULL);
+			goto break_or_fail;
+		}
+		sci->sc_stage.flags |= NILFS_CF_NODE;
+	}
+	/* Collect node */
+	err = nilfs_segctor_apply_buffers(
+		sci, inode, &node_buffers, sc_ops->collect_node);
+	if (unlikely(err))
+		goto break_or_fail;
+
+	nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
+	err = nilfs_segctor_apply_buffers(
+		sci, inode, &node_buffers, sc_ops->collect_bmap);
+	if (unlikely(err))
+		goto break_or_fail;
+
+	nilfs_segctor_end_finfo(sci, inode);
+	sci->sc_stage.flags &= ~NILFS_CF_NODE;
+
+ break_or_fail:
+	return err;
+}
+
+static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
+					 struct inode *inode)
+{
+	LIST_HEAD(data_buffers);
+	size_t n, rest = nilfs_segctor_buffer_rest(sci);
+	int err;
+
+	n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
+					    sci->sc_dsync_start,
+					    sci->sc_dsync_end);
+
+	err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
+					  nilfs_collect_file_data);
+	if (!err) {
+		nilfs_segctor_end_finfo(sci, inode);
+		BUG_ON(n > rest);
+		/* always receive -E2BIG or true error if n > rest */
+	}
+	return err;
+}
+
+static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct list_head *head;
+	struct nilfs_inode_info *ii;
+	int err = 0;
+
+	switch (sci->sc_stage.scnt) {
+	case NILFS_ST_INIT:
+		/* Pre-processes */
+		sci->sc_stage.flags = 0;
+
+		if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
+			sci->sc_nblk_inc = 0;
+			sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
+			if (mode == SC_LSEG_DSYNC) {
+				sci->sc_stage.scnt = NILFS_ST_DSYNC;
+				goto dsync_mode;
+			}
+		}
+
+		sci->sc_stage.dirty_file_ptr = NULL;
+		sci->sc_stage.gc_inode_ptr = NULL;
+		if (mode == SC_FLUSH_DAT) {
+			sci->sc_stage.scnt = NILFS_ST_DAT;
+			goto dat_stage;
+		}
+		sci->sc_stage.scnt++;  /* Fall through */
+	case NILFS_ST_GC:
+		if (nilfs_doing_gc()) {
+			head = &sci->sc_gc_inodes;
+			ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
+						head, i_dirty);
+			list_for_each_entry_continue(ii, head, i_dirty) {
+				err = nilfs_segctor_scan_file(
+					sci, &ii->vfs_inode,
+					&nilfs_sc_file_ops);
+				if (unlikely(err)) {
+					sci->sc_stage.gc_inode_ptr = list_entry(
+						ii->i_dirty.prev,
+						struct nilfs_inode_info,
+						i_dirty);
+					goto break_or_fail;
+				}
+				set_bit(NILFS_I_COLLECTED, &ii->i_state);
+			}
+			sci->sc_stage.gc_inode_ptr = NULL;
+		}
+		sci->sc_stage.scnt++;  /* Fall through */
+	case NILFS_ST_FILE:
+		head = &sci->sc_dirty_files;
+		ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
+					i_dirty);
+		list_for_each_entry_continue(ii, head, i_dirty) {
+			clear_bit(NILFS_I_DIRTY, &ii->i_state);
+
+			err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
+						      &nilfs_sc_file_ops);
+			if (unlikely(err)) {
+				sci->sc_stage.dirty_file_ptr =
+					list_entry(ii->i_dirty.prev,
+						   struct nilfs_inode_info,
+						   i_dirty);
+				goto break_or_fail;
+			}
+			/* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
+			/* XXX: required ? */
+		}
+		sci->sc_stage.dirty_file_ptr = NULL;
+		if (mode == SC_FLUSH_FILE) {
+			sci->sc_stage.scnt = NILFS_ST_DONE;
+			return 0;
+		}
+		sci->sc_stage.scnt++;
+		sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
+		/* Fall through */
+	case NILFS_ST_IFILE:
+		err = nilfs_segctor_scan_file(sci, sbi->s_ifile,
+					      &nilfs_sc_file_ops);
+		if (unlikely(err))
+			break;
+		sci->sc_stage.scnt++;
+		/* Creating a checkpoint */
+		err = nilfs_segctor_create_checkpoint(sci);
+		if (unlikely(err))
+			break;
+		/* Fall through */
+	case NILFS_ST_CPFILE:
+		err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
+					      &nilfs_sc_file_ops);
+		if (unlikely(err))
+			break;
+		sci->sc_stage.scnt++;  /* Fall through */
+	case NILFS_ST_SUFILE:
+		err = nilfs_segctor_prepare_free_segments(sci,
+							  nilfs->ns_sufile);
+		if (unlikely(err))
+			break;
+		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
+					      &nilfs_sc_file_ops);
+		if (unlikely(err))
+			break;
+		sci->sc_stage.scnt++;  /* Fall through */
+	case NILFS_ST_DAT:
+ dat_stage:
+		err = nilfs_segctor_scan_file(sci, nilfs_dat_inode(nilfs),
+					      &nilfs_sc_dat_ops);
+		if (unlikely(err))
+			break;
+		if (mode == SC_FLUSH_DAT) {
+			sci->sc_stage.scnt = NILFS_ST_DONE;
+			return 0;
+		}
+		sci->sc_stage.scnt++;  /* Fall through */
+	case NILFS_ST_SR:
+		if (mode == SC_LSEG_SR) {
+			/* Appending a super root */
+			err = nilfs_segctor_add_super_root(sci);
+			if (unlikely(err))
+				break;
+		}
+		/* End of a logical segment */
+		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
+		sci->sc_stage.scnt = NILFS_ST_DONE;
+		return 0;
+	case NILFS_ST_DSYNC:
+ dsync_mode:
+		sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
+		ii = sci->sc_dsync_inode;
+		if (!test_bit(NILFS_I_BUSY, &ii->i_state))
+			break;
+
+		err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
+		if (unlikely(err))
+			break;
+		sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
+		sci->sc_stage.scnt = NILFS_ST_DONE;
+		return 0;
+	case NILFS_ST_DONE:
+		return 0;
+	default:
+		BUG();
+	}
+
+ break_or_fail:
+	return err;
+}
+
+static int nilfs_touch_segusage(struct inode *sufile, __u64 segnum)
+{
+	struct buffer_head *bh_su;
+	struct nilfs_segment_usage *raw_su;
+	int err;
+
+	err = nilfs_sufile_get_segment_usage(sufile, segnum, &raw_su, &bh_su);
+	if (unlikely(err))
+		return err;
+	nilfs_mdt_mark_buffer_dirty(bh_su);
+	nilfs_mdt_mark_dirty(sufile);
+	nilfs_sufile_put_segment_usage(sufile, segnum, bh_su);
+	return 0;
+}
+
+static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
+					    struct the_nilfs *nilfs)
+{
+	struct nilfs_segment_buffer *segbuf, *n;
+	__u64 nextnum;
+	int err;
+
+	if (list_empty(&sci->sc_segbufs)) {
+		segbuf = nilfs_segbuf_new(sci->sc_super);
+		if (unlikely(!segbuf))
+			return -ENOMEM;
+		list_add(&segbuf->sb_list, &sci->sc_segbufs);
+	} else
+		segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
+
+	nilfs_segbuf_map(segbuf, nilfs->ns_segnum, nilfs->ns_pseg_offset,
+			 nilfs);
+
+	if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
+		nilfs_shift_to_next_segment(nilfs);
+		nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
+	}
+	sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
+
+	err = nilfs_touch_segusage(nilfs->ns_sufile, segbuf->sb_segnum);
+	if (unlikely(err))
+		return err;
+
+	if (nilfs->ns_segnum == nilfs->ns_nextnum) {
+		/* Start from the head of a new full segment */
+		err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
+		if (unlikely(err))
+			return err;
+	} else
+		nextnum = nilfs->ns_nextnum;
+
+	segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
+	nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
+
+	/* truncating segment buffers */
+	list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
+					  sb_list) {
+		list_del_init(&segbuf->sb_list);
+		nilfs_segbuf_free(segbuf);
+	}
+	return 0;
+}
+
+static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
+					 struct the_nilfs *nilfs, int nadd)
+{
+	struct nilfs_segment_buffer *segbuf, *prev, *n;
+	struct inode *sufile = nilfs->ns_sufile;
+	__u64 nextnextnum;
+	LIST_HEAD(list);
+	int err, ret, i;
+
+	prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
+	/*
+	 * Since the segment specified with nextnum might be allocated during
+	 * the previous construction, the buffer including its segusage may
+	 * not be dirty.  The following call ensures that the buffer is dirty
+	 * and will pin the buffer on memory until the sufile is written.
+	 */
+	err = nilfs_touch_segusage(sufile, prev->sb_nextnum);
+	if (unlikely(err))
+		return err;
+
+	for (i = 0; i < nadd; i++) {
+		/* extend segment info */
+		err = -ENOMEM;
+		segbuf = nilfs_segbuf_new(sci->sc_super);
+		if (unlikely(!segbuf))
+			goto failed;
+
+		/* map this buffer to region of segment on-disk */
+		nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
+		sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
+
+		/* allocate the next next full segment */
+		err = nilfs_sufile_alloc(sufile, &nextnextnum);
+		if (unlikely(err))
+			goto failed_segbuf;
+
+		segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
+		nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
+
+		list_add_tail(&segbuf->sb_list, &list);
+		prev = segbuf;
+	}
+	list_splice(&list, sci->sc_segbufs.prev);
+	return 0;
+
+ failed_segbuf:
+	nilfs_segbuf_free(segbuf);
+ failed:
+	list_for_each_entry_safe(segbuf, n, &list, sb_list) {
+		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
+		WARN_ON(ret); /* never fails */
+		list_del_init(&segbuf->sb_list);
+		nilfs_segbuf_free(segbuf);
+	}
+	return err;
+}
+
+static void nilfs_segctor_free_incomplete_segments(struct nilfs_sc_info *sci,
+						   struct the_nilfs *nilfs)
+{
+	struct nilfs_segment_buffer *segbuf;
+	int ret, done = 0;
+
+	segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
+	if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
+		ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
+		WARN_ON(ret); /* never fails */
+	}
+	if (segbuf->sb_io_error) {
+		/* Case 1: The first segment failed */
+		if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
+			/* Case 1a:  Partial segment appended into an existing
+			   segment */
+			nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
+						segbuf->sb_fseg_end);
+		else /* Case 1b:  New full segment */
+			set_nilfs_discontinued(nilfs);
+		done++;
+	}
+
+	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
+		ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
+		WARN_ON(ret); /* never fails */
+		if (!done && segbuf->sb_io_error) {
+			if (segbuf->sb_segnum != nilfs->ns_nextnum)
+				/* Case 2: extended segment (!= next) failed */
+				nilfs_sufile_set_error(nilfs->ns_sufile,
+						       segbuf->sb_segnum);
+			done++;
+		}
+	}
+}
+
+static void nilfs_segctor_clear_segment_buffers(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segment_buffer *segbuf;
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list)
+		nilfs_segbuf_clear(segbuf);
+	sci->sc_super_root = NULL;
+}
+
+static void nilfs_segctor_destroy_segment_buffers(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segment_buffer *segbuf;
+
+	while (!list_empty(&sci->sc_segbufs)) {
+		segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
+		list_del_init(&segbuf->sb_list);
+		nilfs_segbuf_free(segbuf);
+	}
+	/* sci->sc_curseg = NULL; */
+}
+
+static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
+					   struct the_nilfs *nilfs, int err)
+{
+	if (unlikely(err)) {
+		nilfs_segctor_free_incomplete_segments(sci, nilfs);
+		nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
+	}
+	nilfs_segctor_clear_segment_buffers(sci);
+}
+
+static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
+					  struct inode *sufile)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct buffer_head *bh_su;
+	struct nilfs_segment_usage *raw_su;
+	unsigned long live_blocks;
+	int ret;
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
+						     &raw_su, &bh_su);
+		WARN_ON(ret); /* always succeed because bh_su is dirty */
+		live_blocks = segbuf->sb_sum.nblocks +
+			(segbuf->sb_pseg_start - segbuf->sb_fseg_start);
+		raw_su->su_lastmod = cpu_to_le64(sci->sc_seg_ctime);
+		raw_su->su_nblocks = cpu_to_le32(live_blocks);
+		nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
+					       bh_su);
+	}
+}
+
+static void nilfs_segctor_cancel_segusage(struct nilfs_sc_info *sci,
+					  struct inode *sufile)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct buffer_head *bh_su;
+	struct nilfs_segment_usage *raw_su;
+	int ret;
+
+	segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
+	ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
+					     &raw_su, &bh_su);
+	WARN_ON(ret); /* always succeed because bh_su is dirty */
+	raw_su->su_nblocks = cpu_to_le32(segbuf->sb_pseg_start -
+					 segbuf->sb_fseg_start);
+	nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum, bh_su);
+
+	list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
+		ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
+						     &raw_su, &bh_su);
+		WARN_ON(ret); /* always succeed */
+		raw_su->su_nblocks = 0;
+		nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
+					       bh_su);
+	}
+}
+
+static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
+					    struct nilfs_segment_buffer *last,
+					    struct inode *sufile)
+{
+	struct nilfs_segment_buffer *segbuf = last, *n;
+	int ret;
+
+	list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
+					  sb_list) {
+		list_del_init(&segbuf->sb_list);
+		sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
+		ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
+		WARN_ON(ret);
+		nilfs_segbuf_free(segbuf);
+	}
+}
+
+
+static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
+				 struct the_nilfs *nilfs, int mode)
+{
+	struct nilfs_cstage prev_stage = sci->sc_stage;
+	int err, nadd = 1;
+
+	/* Collection retry loop */
+	for (;;) {
+		sci->sc_super_root = NULL;
+		sci->sc_nblk_this_inc = 0;
+		sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
+
+		err = nilfs_segctor_reset_segment_buffer(sci);
+		if (unlikely(err))
+			goto failed;
+
+		err = nilfs_segctor_collect_blocks(sci, mode);
+		sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
+		if (!err)
+			break;
+
+		if (unlikely(err != -E2BIG))
+			goto failed;
+
+		/* The current segment is filled up */
+		if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
+			break;
+
+		nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
+		nilfs_segctor_clear_segment_buffers(sci);
+
+		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
+		if (unlikely(err))
+			return err;
+
+		nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
+		sci->sc_stage = prev_stage;
+	}
+	nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
+	return 0;
+
+ failed:
+	return err;
+}
+
+static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
+				      struct buffer_head *new_bh)
+{
+	BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
+
+	list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
+	/* The caller must release old_bh */
+}
+
+static int
+nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
+				     struct nilfs_segment_buffer *segbuf,
+				     int mode)
+{
+	struct inode *inode = NULL;
+	sector_t blocknr;
+	unsigned long nfinfo = segbuf->sb_sum.nfinfo;
+	unsigned long nblocks = 0, ndatablk = 0;
+	struct nilfs_sc_operations *sc_op = NULL;
+	struct nilfs_segsum_pointer ssp;
+	struct nilfs_finfo *finfo = NULL;
+	union nilfs_binfo binfo;
+	struct buffer_head *bh, *bh_org;
+	ino_t ino = 0;
+	int err = 0;
+
+	if (!nfinfo)
+		goto out;
+
+	blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
+	ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
+	ssp.offset = sizeof(struct nilfs_segment_summary);
+
+	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
+		if (bh == sci->sc_super_root)
+			break;
+		if (!finfo) {
+			finfo =	nilfs_segctor_map_segsum_entry(
+				sci, &ssp, sizeof(*finfo));
+			ino = le64_to_cpu(finfo->fi_ino);
+			nblocks = le32_to_cpu(finfo->fi_nblocks);
+			ndatablk = le32_to_cpu(finfo->fi_ndatablk);
+
+			if (buffer_nilfs_node(bh))
+				inode = NILFS_BTNC_I(bh->b_page->mapping);
+			else
+				inode = NILFS_AS_I(bh->b_page->mapping);
+
+			if (mode == SC_LSEG_DSYNC)
+				sc_op = &nilfs_sc_dsync_ops;
+			else if (ino == NILFS_DAT_INO)
+				sc_op = &nilfs_sc_dat_ops;
+			else /* file blocks */
+				sc_op = &nilfs_sc_file_ops;
+		}
+		bh_org = bh;
+		get_bh(bh_org);
+		err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
+					&binfo);
+		if (bh != bh_org)
+			nilfs_list_replace_buffer(bh_org, bh);
+		brelse(bh_org);
+		if (unlikely(err))
+			goto failed_bmap;
+
+		if (ndatablk > 0)
+			sc_op->write_data_binfo(sci, &ssp, &binfo);
+		else
+			sc_op->write_node_binfo(sci, &ssp, &binfo);
+
+		blocknr++;
+		if (--nblocks == 0) {
+			finfo = NULL;
+			if (--nfinfo == 0)
+				break;
+		} else if (ndatablk > 0)
+			ndatablk--;
+	}
+ out:
+	return 0;
+
+ failed_bmap:
+	err = nilfs_handle_bmap_error(err, __func__, inode, sci->sc_super);
+	return err;
+}
+
+static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
+{
+	struct nilfs_segment_buffer *segbuf;
+	int err;
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
+		if (unlikely(err))
+			return err;
+		nilfs_segbuf_fill_in_segsum(segbuf);
+	}
+	return 0;
+}
+
+static int
+nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
+{
+	struct page *clone_page;
+	struct buffer_head *bh, *head, *bh2;
+	void *kaddr;
+
+	bh = head = page_buffers(page);
+
+	clone_page = nilfs_alloc_private_page(bh->b_bdev, bh->b_size, 0);
+	if (unlikely(!clone_page))
+		return -ENOMEM;
+
+	bh2 = page_buffers(clone_page);
+	kaddr = kmap_atomic(page, KM_USER0);
+	do {
+		if (list_empty(&bh->b_assoc_buffers))
+			continue;
+		get_bh(bh2);
+		page_cache_get(clone_page); /* for each bh */
+		memcpy(bh2->b_data, kaddr + bh_offset(bh), bh2->b_size);
+		bh2->b_blocknr = bh->b_blocknr;
+		list_replace(&bh->b_assoc_buffers, &bh2->b_assoc_buffers);
+		list_add_tail(&bh->b_assoc_buffers, out);
+	} while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (!TestSetPageWriteback(clone_page))
+		inc_zone_page_state(clone_page, NR_WRITEBACK);
+	unlock_page(clone_page);
+
+	return 0;
+}
+
+static int nilfs_test_page_to_be_frozen(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (!mapping || !mapping->host || S_ISDIR(mapping->host->i_mode))
+		return 0;
+
+	if (page_mapped(page)) {
+		ClearPageChecked(page);
+		return 1;
+	}
+	return PageChecked(page);
+}
+
+static int nilfs_begin_page_io(struct page *page, struct list_head *out)
+{
+	if (!page || PageWriteback(page))
+		/* For split b-tree node pages, this function may be called
+		   twice.  We ignore the 2nd or later calls by this check. */
+		return 0;
+
+	lock_page(page);
+	clear_page_dirty_for_io(page);
+	set_page_writeback(page);
+	unlock_page(page);
+
+	if (nilfs_test_page_to_be_frozen(page)) {
+		int err = nilfs_copy_replace_page_buffers(page, out);
+		if (unlikely(err))
+			return err;
+	}
+	return 0;
+}
+
+static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
+				       struct page **failed_page)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct page *bd_page = NULL, *fs_page = NULL;
+	struct list_head *list = &sci->sc_copied_buffers;
+	int err;
+
+	*failed_page = NULL;
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		struct buffer_head *bh;
+
+		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
+				    b_assoc_buffers) {
+			if (bh->b_page != bd_page) {
+				if (bd_page) {
+					lock_page(bd_page);
+					clear_page_dirty_for_io(bd_page);
+					set_page_writeback(bd_page);
+					unlock_page(bd_page);
+				}
+				bd_page = bh->b_page;
+			}
+		}
+
+		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
+				    b_assoc_buffers) {
+			if (bh == sci->sc_super_root) {
+				if (bh->b_page != bd_page) {
+					lock_page(bd_page);
+					clear_page_dirty_for_io(bd_page);
+					set_page_writeback(bd_page);
+					unlock_page(bd_page);
+					bd_page = bh->b_page;
+				}
+				break;
+			}
+			if (bh->b_page != fs_page) {
+				err = nilfs_begin_page_io(fs_page, list);
+				if (unlikely(err)) {
+					*failed_page = fs_page;
+					goto out;
+				}
+				fs_page = bh->b_page;
+			}
+		}
+	}
+	if (bd_page) {
+		lock_page(bd_page);
+		clear_page_dirty_for_io(bd_page);
+		set_page_writeback(bd_page);
+		unlock_page(bd_page);
+	}
+	err = nilfs_begin_page_io(fs_page, list);
+	if (unlikely(err))
+		*failed_page = fs_page;
+ out:
+	return err;
+}
+
+static int nilfs_segctor_write(struct nilfs_sc_info *sci,
+			       struct backing_dev_info *bdi)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct nilfs_write_info wi;
+	int err, res;
+
+	wi.sb = sci->sc_super;
+	wi.bh_sr = sci->sc_super_root;
+	wi.bdi = bdi;
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		nilfs_segbuf_prepare_write(segbuf, &wi);
+		err = nilfs_segbuf_write(segbuf, &wi);
+
+		res = nilfs_segbuf_wait(segbuf, &wi);
+		err = unlikely(err) ? : res;
+		if (unlikely(err))
+			return err;
+	}
+	return 0;
+}
+
+static int nilfs_page_has_uncleared_buffer(struct page *page)
+{
+	struct buffer_head *head, *bh;
+
+	head = bh = page_buffers(page);
+	do {
+		if (buffer_dirty(bh) && !list_empty(&bh->b_assoc_buffers))
+			return 1;
+		bh = bh->b_this_page;
+	} while (bh != head);
+	return 0;
+}
+
+static void __nilfs_end_page_io(struct page *page, int err)
+{
+	if (!err) {
+		if (!nilfs_page_buffers_clean(page))
+			__set_page_dirty_nobuffers(page);
+		ClearPageError(page);
+	} else {
+		__set_page_dirty_nobuffers(page);
+		SetPageError(page);
+	}
+
+	if (buffer_nilfs_allocated(page_buffers(page))) {
+		if (TestClearPageWriteback(page))
+			dec_zone_page_state(page, NR_WRITEBACK);
+	} else
+		end_page_writeback(page);
+}
+
+static void nilfs_end_page_io(struct page *page, int err)
+{
+	if (!page)
+		return;
+
+	if (buffer_nilfs_node(page_buffers(page)) &&
+	    nilfs_page_has_uncleared_buffer(page))
+		/* For b-tree node pages, this function may be called twice
+		   or more because they might be split in a segment.
+		   This check assures that cleanup has been done for all
+		   buffers in a split btnode page. */
+		return;
+
+	__nilfs_end_page_io(page, err);
+}
+
+static void nilfs_clear_copied_buffers(struct list_head *list, int err)
+{
+	struct buffer_head *bh, *head;
+	struct page *page;
+
+	while (!list_empty(list)) {
+		bh = list_entry(list->next, struct buffer_head,
+				b_assoc_buffers);
+		page = bh->b_page;
+		page_cache_get(page);
+		head = bh = page_buffers(page);
+		do {
+			if (!list_empty(&bh->b_assoc_buffers)) {
+				list_del_init(&bh->b_assoc_buffers);
+				if (!err) {
+					set_buffer_uptodate(bh);
+					clear_buffer_dirty(bh);
+					clear_buffer_nilfs_volatile(bh);
+				}
+				brelse(bh); /* for b_assoc_buffers */
+			}
+		} while ((bh = bh->b_this_page) != head);
+
+		__nilfs_end_page_io(page, err);
+		page_cache_release(page);
+	}
+}
+
+static void nilfs_segctor_abort_write(struct nilfs_sc_info *sci,
+				      struct page *failed_page, int err)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct page *bd_page = NULL, *fs_page = NULL;
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		struct buffer_head *bh;
+
+		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
+				    b_assoc_buffers) {
+			if (bh->b_page != bd_page) {
+				if (bd_page)
+					end_page_writeback(bd_page);
+				bd_page = bh->b_page;
+			}
+		}
+
+		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
+				    b_assoc_buffers) {
+			if (bh == sci->sc_super_root) {
+				if (bh->b_page != bd_page) {
+					end_page_writeback(bd_page);
+					bd_page = bh->b_page;
+				}
+				break;
+			}
+			if (bh->b_page != fs_page) {
+				nilfs_end_page_io(fs_page, err);
+				if (unlikely(fs_page == failed_page))
+					goto done;
+				fs_page = bh->b_page;
+			}
+		}
+	}
+	if (bd_page)
+		end_page_writeback(bd_page);
+
+	nilfs_end_page_io(fs_page, err);
+ done:
+	nilfs_clear_copied_buffers(&sci->sc_copied_buffers, err);
+}
+
+static void nilfs_set_next_segment(struct the_nilfs *nilfs,
+				   struct nilfs_segment_buffer *segbuf)
+{
+	nilfs->ns_segnum = segbuf->sb_segnum;
+	nilfs->ns_nextnum = segbuf->sb_nextnum;
+	nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
+		+ segbuf->sb_sum.nblocks;
+	nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
+	nilfs->ns_ctime = segbuf->sb_sum.ctime;
+}
+
+static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segment_buffer *segbuf;
+	struct page *bd_page = NULL, *fs_page = NULL;
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int update_sr = (sci->sc_super_root != NULL);
+
+	list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
+		struct buffer_head *bh;
+
+		list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
+				    b_assoc_buffers) {
+			set_buffer_uptodate(bh);
+			clear_buffer_dirty(bh);
+			if (bh->b_page != bd_page) {
+				if (bd_page)
+					end_page_writeback(bd_page);
+				bd_page = bh->b_page;
+			}
+		}
+		/*
+		 * We assume that the buffers which belong to the same page
+		 * continue over the buffer list.
+		 * Under this assumption, the last BHs of pages is
+		 * identifiable by the discontinuity of bh->b_page
+		 * (page != fs_page).
+		 *
+		 * For B-tree node blocks, however, this assumption is not
+		 * guaranteed.  The cleanup code of B-tree node pages needs
+		 * special care.
+		 */
+		list_for_each_entry(bh, &segbuf->sb_payload_buffers,
+				    b_assoc_buffers) {
+			set_buffer_uptodate(bh);
+			clear_buffer_dirty(bh);
+			clear_buffer_nilfs_volatile(bh);
+			if (bh == sci->sc_super_root) {
+				if (bh->b_page != bd_page) {
+					end_page_writeback(bd_page);
+					bd_page = bh->b_page;
+				}
+				break;
+			}
+			if (bh->b_page != fs_page) {
+				nilfs_end_page_io(fs_page, 0);
+				fs_page = bh->b_page;
+			}
+		}
+
+		if (!NILFS_SEG_SIMPLEX(&segbuf->sb_sum)) {
+			if (NILFS_SEG_LOGBGN(&segbuf->sb_sum)) {
+				set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
+				sci->sc_lseg_stime = jiffies;
+			}
+			if (NILFS_SEG_LOGEND(&segbuf->sb_sum))
+				clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
+		}
+	}
+	/*
+	 * Since pages may continue over multiple segment buffers,
+	 * end of the last page must be checked outside of the loop.
+	 */
+	if (bd_page)
+		end_page_writeback(bd_page);
+
+	nilfs_end_page_io(fs_page, 0);
+
+	nilfs_clear_copied_buffers(&sci->sc_copied_buffers, 0);
+
+	nilfs_drop_collected_inodes(&sci->sc_dirty_files);
+
+	if (nilfs_doing_gc()) {
+		nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
+		if (update_sr)
+			nilfs_commit_gcdat_inode(nilfs);
+	} else
+		nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
+
+	sci->sc_nblk_inc += sci->sc_nblk_this_inc;
+
+	segbuf = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
+	nilfs_set_next_segment(nilfs, segbuf);
+
+	if (update_sr) {
+		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
+				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
+		sbi->s_super->s_dirt = 1;
+
+		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
+		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
+		set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
+	} else
+		clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
+}
+
+static int nilfs_segctor_check_in_files(struct nilfs_sc_info *sci,
+					struct nilfs_sb_info *sbi)
+{
+	struct nilfs_inode_info *ii, *n;
+	__u64 cno = sbi->s_nilfs->ns_cno;
+
+	spin_lock(&sbi->s_inode_lock);
+ retry:
+	list_for_each_entry_safe(ii, n, &sbi->s_dirty_files, i_dirty) {
+		if (!ii->i_bh) {
+			struct buffer_head *ibh;
+			int err;
+
+			spin_unlock(&sbi->s_inode_lock);
+			err = nilfs_ifile_get_inode_block(
+				sbi->s_ifile, ii->vfs_inode.i_ino, &ibh);
+			if (unlikely(err)) {
+				nilfs_warning(sbi->s_super, __func__,
+					      "failed to get inode block.\n");
+				return err;
+			}
+			nilfs_mdt_mark_buffer_dirty(ibh);
+			nilfs_mdt_mark_dirty(sbi->s_ifile);
+			spin_lock(&sbi->s_inode_lock);
+			if (likely(!ii->i_bh))
+				ii->i_bh = ibh;
+			else
+				brelse(ibh);
+			goto retry;
+		}
+		ii->i_cno = cno;
+
+		clear_bit(NILFS_I_QUEUED, &ii->i_state);
+		set_bit(NILFS_I_BUSY, &ii->i_state);
+		list_del(&ii->i_dirty);
+		list_add_tail(&ii->i_dirty, &sci->sc_dirty_files);
+	}
+	spin_unlock(&sbi->s_inode_lock);
+
+	NILFS_I(sbi->s_ifile)->i_cno = cno;
+
+	return 0;
+}
+
+static void nilfs_segctor_check_out_files(struct nilfs_sc_info *sci,
+					  struct nilfs_sb_info *sbi)
+{
+	struct nilfs_transaction_info *ti = current->journal_info;
+	struct nilfs_inode_info *ii, *n;
+	__u64 cno = sbi->s_nilfs->ns_cno;
+
+	spin_lock(&sbi->s_inode_lock);
+	list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
+		if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
+		    test_bit(NILFS_I_DIRTY, &ii->i_state)) {
+			/* The current checkpoint number (=nilfs->ns_cno) is
+			   changed between check-in and check-out only if the
+			   super root is written out.  So, we can update i_cno
+			   for the inodes that remain in the dirty list. */
+			ii->i_cno = cno;
+			continue;
+		}
+		clear_bit(NILFS_I_BUSY, &ii->i_state);
+		brelse(ii->i_bh);
+		ii->i_bh = NULL;
+		list_del(&ii->i_dirty);
+		list_add_tail(&ii->i_dirty, &ti->ti_garbage);
+	}
+	spin_unlock(&sbi->s_inode_lock);
+}
+
+/*
+ * Main procedure of segment constructor
+ */
+static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct page *failed_page;
+	int err, has_sr = 0;
+
+	sci->sc_stage.scnt = NILFS_ST_INIT;
+
+	err = nilfs_segctor_check_in_files(sci, sbi);
+	if (unlikely(err))
+		goto out;
+
+	if (nilfs_test_metadata_dirty(sbi))
+		set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
+
+	if (nilfs_segctor_clean(sci))
+		goto out;
+
+	do {
+		sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
+
+		err = nilfs_segctor_begin_construction(sci, nilfs);
+		if (unlikely(err))
+			goto out;
+
+		/* Update time stamp */
+		sci->sc_seg_ctime = get_seconds();
+
+		err = nilfs_segctor_collect(sci, nilfs, mode);
+		if (unlikely(err))
+			goto failed;
+
+		has_sr = (sci->sc_super_root != NULL);
+
+		/* Avoid empty segment */
+		if (sci->sc_stage.scnt == NILFS_ST_DONE &&
+		    NILFS_SEG_EMPTY(&sci->sc_curseg->sb_sum)) {
+			nilfs_segctor_end_construction(sci, nilfs, 1);
+			goto out;
+		}
+
+		err = nilfs_segctor_assign(sci, mode);
+		if (unlikely(err))
+			goto failed;
+
+		if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
+			nilfs_segctor_fill_in_file_bmap(sci, sbi->s_ifile);
+
+		if (has_sr) {
+			err = nilfs_segctor_fill_in_checkpoint(sci);
+			if (unlikely(err))
+				goto failed_to_make_up;
+
+			nilfs_segctor_fill_in_super_root(sci, nilfs);
+		}
+		nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
+
+		/* Write partial segments */
+		err = nilfs_segctor_prepare_write(sci, &failed_page);
+		if (unlikely(err))
+			goto failed_to_write;
+
+		nilfs_segctor_fill_in_checksums(sci, nilfs->ns_crc_seed);
+
+		err = nilfs_segctor_write(sci, nilfs->ns_bdi);
+		if (unlikely(err))
+			goto failed_to_write;
+
+		nilfs_segctor_complete_write(sci);
+
+		/* Commit segments */
+		if (has_sr) {
+			nilfs_segctor_commit_free_segments(sci);
+			nilfs_segctor_clear_metadata_dirty(sci);
+		}
+
+		nilfs_segctor_end_construction(sci, nilfs, 0);
+
+	} while (sci->sc_stage.scnt != NILFS_ST_DONE);
+
+ out:
+	nilfs_segctor_destroy_segment_buffers(sci);
+	nilfs_segctor_check_out_files(sci, sbi);
+	return err;
+
+ failed_to_write:
+	nilfs_segctor_abort_write(sci, failed_page, err);
+	nilfs_segctor_cancel_segusage(sci, nilfs->ns_sufile);
+
+ failed_to_make_up:
+	if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
+		nilfs_redirty_inodes(&sci->sc_dirty_files);
+
+ failed:
+	if (nilfs_doing_gc())
+		nilfs_redirty_inodes(&sci->sc_gc_inodes);
+	nilfs_segctor_end_construction(sci, nilfs, err);
+	goto out;
+}
+
+/**
+ * nilfs_secgtor_start_timer - set timer of background write
+ * @sci: nilfs_sc_info
+ *
+ * If the timer has already been set, it ignores the new request.
+ * This function MUST be called within a section locking the segment
+ * semaphore.
+ */
+static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
+{
+	spin_lock(&sci->sc_state_lock);
+	if (sci->sc_timer && !(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
+		sci->sc_timer->expires = jiffies + sci->sc_interval;
+		add_timer(sci->sc_timer);
+		sci->sc_state |= NILFS_SEGCTOR_COMMIT;
+	}
+	spin_unlock(&sci->sc_state_lock);
+}
+
+static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
+{
+	spin_lock(&sci->sc_state_lock);
+	if (!(sci->sc_flush_request & (1 << bn))) {
+		unsigned long prev_req = sci->sc_flush_request;
+
+		sci->sc_flush_request |= (1 << bn);
+		if (!prev_req)
+			wake_up(&sci->sc_wait_daemon);
+	}
+	spin_unlock(&sci->sc_state_lock);
+}
+
+/**
+ * nilfs_flush_segment - trigger a segment construction for resource control
+ * @sb: super block
+ * @ino: inode number of the file to be flushed out.
+ */
+void nilfs_flush_segment(struct super_block *sb, ino_t ino)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_sc_info *sci = NILFS_SC(sbi);
+
+	if (!sci || nilfs_doing_construction())
+		return;
+	nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
+					/* assign bit 0 to data files */
+}
+
+int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *sci,
+					   __u64 *segnum, size_t nsegs)
+{
+	struct nilfs_segment_entry *ent;
+	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
+	struct inode *sufile = nilfs->ns_sufile;
+	LIST_HEAD(list);
+	__u64 *pnum;
+	size_t i;
+	int err;
+
+	for (pnum = segnum, i = 0; i < nsegs; pnum++, i++) {
+		ent = nilfs_alloc_segment_entry(*pnum);
+		if (unlikely(!ent)) {
+			err = -ENOMEM;
+			goto failed;
+		}
+		list_add_tail(&ent->list, &list);
+
+		err = nilfs_open_segment_entry(ent, sufile);
+		if (unlikely(err))
+			goto failed;
+
+		if (unlikely(!nilfs_segment_usage_dirty(ent->raw_su)))
+			printk(KERN_WARNING "NILFS: unused segment is "
+			       "requested to be cleaned (segnum=%llu)\n",
+			       (unsigned long long)ent->segnum);
+		nilfs_close_segment_entry(ent, sufile);
+	}
+	list_splice(&list, sci->sc_cleaning_segments.prev);
+	return 0;
+
+ failed:
+	nilfs_dispose_segment_list(&list);
+	return err;
+}
+
+void nilfs_segctor_clear_segments_to_be_freed(struct nilfs_sc_info *sci)
+{
+	nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
+}
+
+struct nilfs_segctor_wait_request {
+	wait_queue_t	wq;
+	__u32		seq;
+	int		err;
+	atomic_t	done;
+};
+
+static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
+{
+	struct nilfs_segctor_wait_request wait_req;
+	int err = 0;
+
+	spin_lock(&sci->sc_state_lock);
+	init_wait(&wait_req.wq);
+	wait_req.err = 0;
+	atomic_set(&wait_req.done, 0);
+	wait_req.seq = ++sci->sc_seq_request;
+	spin_unlock(&sci->sc_state_lock);
+
+	init_waitqueue_entry(&wait_req.wq, current);
+	add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
+	set_current_state(TASK_INTERRUPTIBLE);
+	wake_up(&sci->sc_wait_daemon);
+
+	for (;;) {
+		if (atomic_read(&wait_req.done)) {
+			err = wait_req.err;
+			break;
+		}
+		if (!signal_pending(current)) {
+			schedule();
+			continue;
+		}
+		err = -ERESTARTSYS;
+		break;
+	}
+	finish_wait(&sci->sc_wait_request, &wait_req.wq);
+	return err;
+}
+
+static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
+{
+	struct nilfs_segctor_wait_request *wrq, *n;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
+	list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
+				 wq.task_list) {
+		if (!atomic_read(&wrq->done) &&
+		    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
+			wrq->err = err;
+			atomic_set(&wrq->done, 1);
+		}
+		if (atomic_read(&wrq->done)) {
+			wrq->wq.func(&wrq->wq,
+				     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
+				     0, NULL);
+		}
+	}
+	spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
+}
+
+/**
+ * nilfs_construct_segment - construct a logical segment
+ * @sb: super block
+ *
+ * Return Value: On success, 0 is retured. On errors, one of the following
+ * negative error code is returned.
+ *
+ * %-EROFS - Read only filesystem.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOSPC - No space left on device (only in a panic state).
+ *
+ * %-ERESTARTSYS - Interrupted.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ */
+int nilfs_construct_segment(struct super_block *sb)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_sc_info *sci = NILFS_SC(sbi);
+	struct nilfs_transaction_info *ti;
+	int err;
+
+	if (!sci)
+		return -EROFS;
+
+	/* A call inside transactions causes a deadlock. */
+	BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
+
+	err = nilfs_segctor_sync(sci);
+	return err;
+}
+
+/**
+ * nilfs_construct_dsync_segment - construct a data-only logical segment
+ * @sb: super block
+ * @inode: inode whose data blocks should be written out
+ * @start: start byte offset
+ * @end: end byte offset (inclusive)
+ *
+ * Return Value: On success, 0 is retured. On errors, one of the following
+ * negative error code is returned.
+ *
+ * %-EROFS - Read only filesystem.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOSPC - No space left on device (only in a panic state).
+ *
+ * %-ERESTARTSYS - Interrupted.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ */
+int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
+				  loff_t start, loff_t end)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_sc_info *sci = NILFS_SC(sbi);
+	struct nilfs_inode_info *ii;
+	struct nilfs_transaction_info ti;
+	int err = 0;
+
+	if (!sci)
+		return -EROFS;
+
+	nilfs_transaction_lock(sbi, &ti, 0);
+
+	ii = NILFS_I(inode);
+	if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
+	    nilfs_test_opt(sbi, STRICT_ORDER) ||
+	    test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
+	    nilfs_discontinued(sbi->s_nilfs)) {
+		nilfs_transaction_unlock(sbi);
+		err = nilfs_segctor_sync(sci);
+		return err;
+	}
+
+	spin_lock(&sbi->s_inode_lock);
+	if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
+	    !test_bit(NILFS_I_BUSY, &ii->i_state)) {
+		spin_unlock(&sbi->s_inode_lock);
+		nilfs_transaction_unlock(sbi);
+		return 0;
+	}
+	spin_unlock(&sbi->s_inode_lock);
+	sci->sc_dsync_inode = ii;
+	sci->sc_dsync_start = start;
+	sci->sc_dsync_end = end;
+
+	err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
+
+	nilfs_transaction_unlock(sbi);
+	return err;
+}
+
+struct nilfs_segctor_req {
+	int mode;
+	__u32 seq_accepted;
+	int sc_err;  /* construction failure */
+	int sb_err;  /* super block writeback failure */
+};
+
+#define FLUSH_FILE_BIT	(0x1) /* data file only */
+#define FLUSH_DAT_BIT	(1 << NILFS_DAT_INO) /* DAT only */
+
+static void nilfs_segctor_accept(struct nilfs_sc_info *sci,
+				 struct nilfs_segctor_req *req)
+{
+	req->sc_err = req->sb_err = 0;
+	spin_lock(&sci->sc_state_lock);
+	req->seq_accepted = sci->sc_seq_request;
+	spin_unlock(&sci->sc_state_lock);
+
+	if (sci->sc_timer)
+		del_timer_sync(sci->sc_timer);
+}
+
+static void nilfs_segctor_notify(struct nilfs_sc_info *sci,
+				 struct nilfs_segctor_req *req)
+{
+	/* Clear requests (even when the construction failed) */
+	spin_lock(&sci->sc_state_lock);
+
+	sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
+
+	if (req->mode == SC_LSEG_SR) {
+		sci->sc_seq_done = req->seq_accepted;
+		nilfs_segctor_wakeup(sci, req->sc_err ? : req->sb_err);
+		sci->sc_flush_request = 0;
+	} else if (req->mode == SC_FLUSH_FILE)
+		sci->sc_flush_request &= ~FLUSH_FILE_BIT;
+	else if (req->mode == SC_FLUSH_DAT)
+		sci->sc_flush_request &= ~FLUSH_DAT_BIT;
+
+	spin_unlock(&sci->sc_state_lock);
+}
+
+static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
+				   struct nilfs_segctor_req *req)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int err = 0;
+
+	if (nilfs_discontinued(nilfs))
+		req->mode = SC_LSEG_SR;
+	if (!nilfs_segctor_confirm(sci)) {
+		err = nilfs_segctor_do_construct(sci, req->mode);
+		req->sc_err = err;
+	}
+	if (likely(!err)) {
+		if (req->mode != SC_FLUSH_DAT)
+			atomic_set(&nilfs->ns_ndirtyblks, 0);
+		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
+		    nilfs_discontinued(nilfs)) {
+			down_write(&nilfs->ns_sem);
+			req->sb_err = nilfs_commit_super(sbi, 0);
+			up_write(&nilfs->ns_sem);
+		}
+	}
+	return err;
+}
+
+static void nilfs_construction_timeout(unsigned long data)
+{
+	struct task_struct *p = (struct task_struct *)data;
+	wake_up_process(p);
+}
+
+static void
+nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
+{
+	struct nilfs_inode_info *ii, *n;
+
+	list_for_each_entry_safe(ii, n, head, i_dirty) {
+		if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
+			continue;
+		hlist_del_init(&ii->vfs_inode.i_hash);
+		list_del_init(&ii->i_dirty);
+		nilfs_clear_gcinode(&ii->vfs_inode);
+	}
+}
+
+int nilfs_clean_segments(struct super_block *sb, void __user *argp)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_sc_info *sci = NILFS_SC(sbi);
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct nilfs_transaction_info ti;
+	struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
+	int err;
+
+	if (unlikely(!sci))
+		return -EROFS;
+
+	nilfs_transaction_lock(sbi, &ti, 1);
+
+	err = nilfs_init_gcdat_inode(nilfs);
+	if (unlikely(err))
+		goto out_unlock;
+	err = nilfs_ioctl_prepare_clean_segments(nilfs, argp);
+	if (unlikely(err))
+		goto out_unlock;
+
+	list_splice_init(&nilfs->ns_gc_inodes, sci->sc_gc_inodes.prev);
+
+	for (;;) {
+		nilfs_segctor_accept(sci, &req);
+		err = nilfs_segctor_construct(sci, &req);
+		nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
+		nilfs_segctor_notify(sci, &req);
+
+		if (likely(!err))
+			break;
+
+		nilfs_warning(sb, __func__,
+			      "segment construction failed. (err=%d)", err);
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(sci->sc_interval);
+	}
+
+ out_unlock:
+	nilfs_clear_gcdat_inode(nilfs);
+	nilfs_transaction_unlock(sbi);
+	return err;
+}
+
+static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	struct nilfs_transaction_info ti;
+	struct nilfs_segctor_req req = { .mode = mode };
+
+	nilfs_transaction_lock(sbi, &ti, 0);
+
+	nilfs_segctor_accept(sci, &req);
+	nilfs_segctor_construct(sci, &req);
+	nilfs_segctor_notify(sci, &req);
+
+	/*
+	 * Unclosed segment should be retried.  We do this using sc_timer.
+	 * Timeout of sc_timer will invoke complete construction which leads
+	 * to close the current logical segment.
+	 */
+	if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
+		nilfs_segctor_start_timer(sci);
+
+	nilfs_transaction_unlock(sbi);
+}
+
+static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
+{
+	int mode = 0;
+	int err;
+
+	spin_lock(&sci->sc_state_lock);
+	mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
+		SC_FLUSH_DAT : SC_FLUSH_FILE;
+	spin_unlock(&sci->sc_state_lock);
+
+	if (mode) {
+		err = nilfs_segctor_do_construct(sci, mode);
+
+		spin_lock(&sci->sc_state_lock);
+		sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
+			~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
+		spin_unlock(&sci->sc_state_lock);
+	}
+	clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
+}
+
+static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
+{
+	if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
+	    time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
+		if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
+			return SC_FLUSH_FILE;
+		else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
+			return SC_FLUSH_DAT;
+	}
+	return SC_LSEG_SR;
+}
+
+/**
+ * nilfs_segctor_thread - main loop of the segment constructor thread.
+ * @arg: pointer to a struct nilfs_sc_info.
+ *
+ * nilfs_segctor_thread() initializes a timer and serves as a daemon
+ * to execute segment constructions.
+ */
+static int nilfs_segctor_thread(void *arg)
+{
+	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
+	struct timer_list timer;
+	int timeout = 0;
+
+	init_timer(&timer);
+	timer.data = (unsigned long)current;
+	timer.function = nilfs_construction_timeout;
+	sci->sc_timer = &timer;
+
+	/* start sync. */
+	sci->sc_task = current;
+	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
+	printk(KERN_INFO
+	       "segctord starting. Construction interval = %lu seconds, "
+	       "CP frequency < %lu seconds\n",
+	       sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
+
+	spin_lock(&sci->sc_state_lock);
+ loop:
+	for (;;) {
+		int mode;
+
+		if (sci->sc_state & NILFS_SEGCTOR_QUIT)
+			goto end_thread;
+
+		if (timeout || sci->sc_seq_request != sci->sc_seq_done)
+			mode = SC_LSEG_SR;
+		else if (!sci->sc_flush_request)
+			break;
+		else
+			mode = nilfs_segctor_flush_mode(sci);
+
+		spin_unlock(&sci->sc_state_lock);
+		nilfs_segctor_thread_construct(sci, mode);
+		spin_lock(&sci->sc_state_lock);
+		timeout = 0;
+	}
+
+
+	if (freezing(current)) {
+		spin_unlock(&sci->sc_state_lock);
+		refrigerator();
+		spin_lock(&sci->sc_state_lock);
+	} else {
+		DEFINE_WAIT(wait);
+		int should_sleep = 1;
+
+		prepare_to_wait(&sci->sc_wait_daemon, &wait,
+				TASK_INTERRUPTIBLE);
+
+		if (sci->sc_seq_request != sci->sc_seq_done)
+			should_sleep = 0;
+		else if (sci->sc_flush_request)
+			should_sleep = 0;
+		else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
+			should_sleep = time_before(jiffies,
+						   sci->sc_timer->expires);
+
+		if (should_sleep) {
+			spin_unlock(&sci->sc_state_lock);
+			schedule();
+			spin_lock(&sci->sc_state_lock);
+		}
+		finish_wait(&sci->sc_wait_daemon, &wait);
+		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
+			   time_after_eq(jiffies, sci->sc_timer->expires));
+	}
+	goto loop;
+
+ end_thread:
+	spin_unlock(&sci->sc_state_lock);
+	del_timer_sync(sci->sc_timer);
+	sci->sc_timer = NULL;
+
+	/* end sync. */
+	sci->sc_task = NULL;
+	wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
+	return 0;
+}
+
+static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
+{
+	struct task_struct *t;
+
+	t = kthread_run(nilfs_segctor_thread, sci, "segctord");
+	if (IS_ERR(t)) {
+		int err = PTR_ERR(t);
+
+		printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
+		       err);
+		return err;
+	}
+	wait_event(sci->sc_wait_task, sci->sc_task != NULL);
+	return 0;
+}
+
+static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
+{
+	sci->sc_state |= NILFS_SEGCTOR_QUIT;
+
+	while (sci->sc_task) {
+		wake_up(&sci->sc_wait_daemon);
+		spin_unlock(&sci->sc_state_lock);
+		wait_event(sci->sc_wait_task, sci->sc_task == NULL);
+		spin_lock(&sci->sc_state_lock);
+	}
+}
+
+static int nilfs_segctor_init(struct nilfs_sc_info *sci)
+{
+	sci->sc_seq_done = sci->sc_seq_request;
+
+	return nilfs_segctor_start_thread(sci);
+}
+
+/*
+ * Setup & clean-up functions
+ */
+static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
+{
+	struct nilfs_sc_info *sci;
+
+	sci = kzalloc(sizeof(*sci), GFP_KERNEL);
+	if (!sci)
+		return NULL;
+
+	sci->sc_sbi = sbi;
+	sci->sc_super = sbi->s_super;
+
+	init_waitqueue_head(&sci->sc_wait_request);
+	init_waitqueue_head(&sci->sc_wait_daemon);
+	init_waitqueue_head(&sci->sc_wait_task);
+	spin_lock_init(&sci->sc_state_lock);
+	INIT_LIST_HEAD(&sci->sc_dirty_files);
+	INIT_LIST_HEAD(&sci->sc_segbufs);
+	INIT_LIST_HEAD(&sci->sc_gc_inodes);
+	INIT_LIST_HEAD(&sci->sc_cleaning_segments);
+	INIT_LIST_HEAD(&sci->sc_copied_buffers);
+
+	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
+	sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
+	sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
+
+	if (sbi->s_interval)
+		sci->sc_interval = sbi->s_interval;
+	if (sbi->s_watermark)
+		sci->sc_watermark = sbi->s_watermark;
+	return sci;
+}
+
+static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
+{
+	int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
+
+	/* The segctord thread was stopped and its timer was removed.
+	   But some tasks remain. */
+	do {
+		struct nilfs_sb_info *sbi = sci->sc_sbi;
+		struct nilfs_transaction_info ti;
+		struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
+
+		nilfs_transaction_lock(sbi, &ti, 0);
+		nilfs_segctor_accept(sci, &req);
+		ret = nilfs_segctor_construct(sci, &req);
+		nilfs_segctor_notify(sci, &req);
+		nilfs_transaction_unlock(sbi);
+
+	} while (ret && retrycount-- > 0);
+}
+
+/**
+ * nilfs_segctor_destroy - destroy the segment constructor.
+ * @sci: nilfs_sc_info
+ *
+ * nilfs_segctor_destroy() kills the segctord thread and frees
+ * the nilfs_sc_info struct.
+ * Caller must hold the segment semaphore.
+ */
+static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
+{
+	struct nilfs_sb_info *sbi = sci->sc_sbi;
+	int flag;
+
+	up_write(&sbi->s_nilfs->ns_segctor_sem);
+
+	spin_lock(&sci->sc_state_lock);
+	nilfs_segctor_kill_thread(sci);
+	flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
+		|| sci->sc_seq_request != sci->sc_seq_done);
+	spin_unlock(&sci->sc_state_lock);
+
+	if (flag || nilfs_segctor_confirm(sci))
+		nilfs_segctor_write_out(sci);
+
+	WARN_ON(!list_empty(&sci->sc_copied_buffers));
+
+	if (!list_empty(&sci->sc_dirty_files)) {
+		nilfs_warning(sbi->s_super, __func__,
+			      "dirty file(s) after the final construction\n");
+		nilfs_dispose_list(sbi, &sci->sc_dirty_files, 1);
+	}
+
+	if (!list_empty(&sci->sc_cleaning_segments))
+		nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
+
+	WARN_ON(!list_empty(&sci->sc_segbufs));
+
+	down_write(&sbi->s_nilfs->ns_segctor_sem);
+
+	kfree(sci);
+}
+
+/**
+ * nilfs_attach_segment_constructor - attach a segment constructor
+ * @sbi: nilfs_sb_info
+ *
+ * nilfs_attach_segment_constructor() allocates a struct nilfs_sc_info,
+ * initilizes it, and starts the segment constructor.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ */
+int nilfs_attach_segment_constructor(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int err;
+
+	/* Each field of nilfs_segctor is cleared through the initialization
+	   of super-block info */
+	sbi->s_sc_info = nilfs_segctor_new(sbi);
+	if (!sbi->s_sc_info)
+		return -ENOMEM;
+
+	nilfs_attach_writer(nilfs, sbi);
+	err = nilfs_segctor_init(NILFS_SC(sbi));
+	if (err) {
+		nilfs_detach_writer(nilfs, sbi);
+		kfree(sbi->s_sc_info);
+		sbi->s_sc_info = NULL;
+	}
+	return err;
+}
+
+/**
+ * nilfs_detach_segment_constructor - destroy the segment constructor
+ * @sbi: nilfs_sb_info
+ *
+ * nilfs_detach_segment_constructor() kills the segment constructor daemon,
+ * frees the struct nilfs_sc_info, and destroy the dirty file list.
+ */
+void nilfs_detach_segment_constructor(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	LIST_HEAD(garbage_list);
+
+	down_write(&nilfs->ns_segctor_sem);
+	if (NILFS_SC(sbi)) {
+		nilfs_segctor_destroy(NILFS_SC(sbi));
+		sbi->s_sc_info = NULL;
+	}
+
+	/* Force to free the list of dirty files */
+	spin_lock(&sbi->s_inode_lock);
+	if (!list_empty(&sbi->s_dirty_files)) {
+		list_splice_init(&sbi->s_dirty_files, &garbage_list);
+		nilfs_warning(sbi->s_super, __func__,
+			      "Non empty dirty list after the last "
+			      "segment construction\n");
+	}
+	spin_unlock(&sbi->s_inode_lock);
+	up_write(&nilfs->ns_segctor_sem);
+
+	nilfs_dispose_list(sbi, &garbage_list, 1);
+	nilfs_detach_writer(nilfs, sbi);
+}
diff --git a/fs/nilfs2/segment.h b/fs/nilfs2/segment.h
new file mode 100644
index 00000000000..a98fc1ed0bb
--- /dev/null
+++ b/fs/nilfs2/segment.h
@@ -0,0 +1,243 @@
+/*
+ * segment.h - NILFS Segment constructor prototypes and definitions
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+#ifndef _NILFS_SEGMENT_H
+#define _NILFS_SEGMENT_H
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+#include "sb.h"
+
+/**
+ * struct nilfs_recovery_info - Recovery infomation
+ * @ri_need_recovery: Recovery status
+ * @ri_super_root: Block number of the last super root
+ * @ri_ri_cno: Number of the last checkpoint
+ * @ri_lsegs_start: Region for roll-forwarding (start block number)
+ * @ri_lsegs_end: Region for roll-forwarding (end block number)
+ * @ri_lseg_start_seq: Sequence value of the segment at ri_lsegs_start
+ * @ri_used_segments: List of segments to be mark active
+ * @ri_pseg_start: Block number of the last partial segment
+ * @ri_seq: Sequence number on the last partial segment
+ * @ri_segnum: Segment number on the last partial segment
+ * @ri_nextnum: Next segment number on the last partial segment
+ */
+struct nilfs_recovery_info {
+	int			ri_need_recovery;
+	sector_t		ri_super_root;
+	__u64			ri_cno;
+
+	sector_t		ri_lsegs_start;
+	sector_t		ri_lsegs_end;
+	u64			ri_lsegs_start_seq;
+	struct list_head	ri_used_segments;
+	sector_t		ri_pseg_start;
+	u64			ri_seq;
+	__u64			ri_segnum;
+	__u64			ri_nextnum;
+};
+
+/* ri_need_recovery */
+#define NILFS_RECOVERY_SR_UPDATED	 1  /* The super root was updated */
+#define NILFS_RECOVERY_ROLLFORWARD_DONE	 2  /* Rollforward was carried out */
+
+/**
+ * struct nilfs_cstage - Context of collection stage
+ * @scnt: Stage count
+ * @flags: State flags
+ * @dirty_file_ptr: Pointer on dirty_files list, or inode of a target file
+ * @gc_inode_ptr: Pointer on the list of gc-inodes
+ */
+struct nilfs_cstage {
+	int			scnt;
+	unsigned 		flags;
+	struct nilfs_inode_info *dirty_file_ptr;
+	struct nilfs_inode_info *gc_inode_ptr;
+};
+
+struct nilfs_segment_buffer;
+
+struct nilfs_segsum_pointer {
+	struct buffer_head     *bh;
+	unsigned		offset; /* offset in bytes */
+};
+
+/**
+ * struct nilfs_sc_info - Segment constructor information
+ * @sc_super: Back pointer to super_block struct
+ * @sc_sbi: Back pointer to nilfs_sb_info struct
+ * @sc_nblk_inc: Block count of current generation
+ * @sc_dirty_files: List of files to be written
+ * @sc_gc_inodes: List of GC inodes having blocks to be written
+ * @sc_cleaning_segments: List of segments to be freed through construction
+ * @sc_copied_buffers: List of copied buffers (buffer heads) to freeze data
+ * @sc_dsync_inode: inode whose data pages are written for a sync operation
+ * @sc_dsync_start: start byte offset of data pages
+ * @sc_dsync_end: end byte offset of data pages (inclusive)
+ * @sc_segbufs: List of segment buffers
+ * @sc_segbuf_nblocks: Number of available blocks in segment buffers.
+ * @sc_curseg: Current segment buffer
+ * @sc_super_root: Pointer to the super root buffer
+ * @sc_stage: Collection stage
+ * @sc_finfo_ptr: pointer to the current finfo struct in the segment summary
+ * @sc_binfo_ptr: pointer to the current binfo struct in the segment summary
+ * @sc_blk_cnt:	Block count of a file
+ * @sc_datablk_cnt: Data block count of a file
+ * @sc_nblk_this_inc: Number of blocks included in the current logical segment
+ * @sc_seg_ctime: Creation time
+ * @sc_flags: Internal flags
+ * @sc_state_lock: spinlock for sc_state and so on
+ * @sc_state: Segctord state flags
+ * @sc_flush_request: inode bitmap of metadata files to be flushed
+ * @sc_wait_request: Client request queue
+ * @sc_wait_daemon: Daemon wait queue
+ * @sc_wait_task: Start/end wait queue to control segctord task
+ * @sc_seq_request: Request counter
+ * @sc_seq_done: Completion counter
+ * @sc_sync: Request of explicit sync operation
+ * @sc_interval: Timeout value of background construction
+ * @sc_mjcp_freq: Frequency of creating checkpoints
+ * @sc_lseg_stime: Start time of the latest logical segment
+ * @sc_watermark: Watermark for the number of dirty buffers
+ * @sc_timer: Timer for segctord
+ * @sc_task: current thread of segctord
+ */
+struct nilfs_sc_info {
+	struct super_block     *sc_super;
+	struct nilfs_sb_info   *sc_sbi;
+
+	unsigned long		sc_nblk_inc;
+
+	struct list_head	sc_dirty_files;
+	struct list_head	sc_gc_inodes;
+	struct list_head	sc_cleaning_segments;
+	struct list_head	sc_copied_buffers;
+
+	struct nilfs_inode_info *sc_dsync_inode;
+	loff_t			sc_dsync_start;
+	loff_t			sc_dsync_end;
+
+	/* Segment buffers */
+	struct list_head	sc_segbufs;
+	unsigned long		sc_segbuf_nblocks;
+	struct nilfs_segment_buffer *sc_curseg;
+	struct buffer_head     *sc_super_root;
+
+	struct nilfs_cstage	sc_stage;
+
+	struct nilfs_segsum_pointer sc_finfo_ptr;
+	struct nilfs_segsum_pointer sc_binfo_ptr;
+	unsigned long		sc_blk_cnt;
+	unsigned long		sc_datablk_cnt;
+	unsigned long		sc_nblk_this_inc;
+	time_t			sc_seg_ctime;
+
+	unsigned long		sc_flags;
+
+	spinlock_t		sc_state_lock;
+	unsigned long		sc_state;
+	unsigned long		sc_flush_request;
+
+	wait_queue_head_t	sc_wait_request;
+	wait_queue_head_t	sc_wait_daemon;
+	wait_queue_head_t	sc_wait_task;
+
+	__u32			sc_seq_request;
+	__u32			sc_seq_done;
+
+	int			sc_sync;
+	unsigned long		sc_interval;
+	unsigned long		sc_mjcp_freq;
+	unsigned long		sc_lseg_stime;	/* in 1/HZ seconds */
+	unsigned long		sc_watermark;
+
+	struct timer_list      *sc_timer;
+	struct task_struct     *sc_task;
+};
+
+/* sc_flags */
+enum {
+	NILFS_SC_DIRTY,		/* One or more dirty meta-data blocks exist */
+	NILFS_SC_UNCLOSED,	/* Logical segment is not closed */
+	NILFS_SC_SUPER_ROOT,	/* The latest segment has a super root */
+	NILFS_SC_PRIOR_FLUSH,	/* Requesting immediate flush without making a
+				   checkpoint */
+	NILFS_SC_HAVE_DELTA,	/* Next checkpoint will have update of files
+				   other than DAT, cpfile, sufile, or files
+				   moved by GC */
+};
+
+/* sc_state */
+#define NILFS_SEGCTOR_QUIT	    0x0001  /* segctord is being destroyed */
+#define NILFS_SEGCTOR_COMMIT	    0x0004  /* committed transaction exists */
+
+/*
+ * Constant parameters
+ */
+#define NILFS_SC_CLEANUP_RETRY	    3  /* Retry count of construction when
+					  destroying segctord */
+
+/*
+ * Default values of timeout, in seconds.
+ */
+#define NILFS_SC_DEFAULT_TIMEOUT    5   /* Timeout value of dirty blocks.
+					   It triggers construction of a
+					   logical segment with a super root */
+#define NILFS_SC_DEFAULT_SR_FREQ    30  /* Maximum frequency of super root
+					   creation */
+
+/*
+ * The default threshold amount of data, in block counts.
+ */
+#define NILFS_SC_DEFAULT_WATERMARK  3600
+
+
+/* segment.c */
+extern int nilfs_init_transaction_cache(void);
+extern void nilfs_destroy_transaction_cache(void);
+extern void nilfs_relax_pressure_in_lock(struct super_block *);
+
+extern int nilfs_construct_segment(struct super_block *);
+extern int nilfs_construct_dsync_segment(struct super_block *, struct inode *,
+					 loff_t, loff_t);
+extern void nilfs_flush_segment(struct super_block *, ino_t);
+extern int nilfs_clean_segments(struct super_block *, void __user *);
+
+extern int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *,
+						  __u64 *, size_t);
+extern void nilfs_segctor_clear_segments_to_be_freed(struct nilfs_sc_info *);
+
+extern int nilfs_attach_segment_constructor(struct nilfs_sb_info *);
+extern void nilfs_detach_segment_constructor(struct nilfs_sb_info *);
+
+/* recovery.c */
+extern int nilfs_read_super_root_block(struct super_block *, sector_t,
+				       struct buffer_head **, int);
+extern int nilfs_search_super_root(struct the_nilfs *, struct nilfs_sb_info *,
+				   struct nilfs_recovery_info *);
+extern int nilfs_recover_logical_segments(struct the_nilfs *,
+					  struct nilfs_sb_info *,
+					  struct nilfs_recovery_info *);
+
+#endif /* _NILFS_SEGMENT_H */
diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
new file mode 100644
index 00000000000..c774cf397e2
--- /dev/null
+++ b/fs/nilfs2/sufile.c
@@ -0,0 +1,640 @@
+/*
+ * sufile.c - NILFS segment usage file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/errno.h>
+#include <linux/nilfs2_fs.h>
+#include "mdt.h"
+#include "sufile.h"
+
+
+static inline unsigned long
+nilfs_sufile_segment_usages_per_block(const struct inode *sufile)
+{
+	return NILFS_MDT(sufile)->mi_entries_per_block;
+}
+
+static unsigned long
+nilfs_sufile_get_blkoff(const struct inode *sufile, __u64 segnum)
+{
+	__u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
+	do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
+	return (unsigned long)t;
+}
+
+static unsigned long
+nilfs_sufile_get_offset(const struct inode *sufile, __u64 segnum)
+{
+	__u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
+	return do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
+}
+
+static unsigned long
+nilfs_sufile_segment_usages_in_block(const struct inode *sufile, __u64 curr,
+				     __u64 max)
+{
+	return min_t(unsigned long,
+		     nilfs_sufile_segment_usages_per_block(sufile) -
+		     nilfs_sufile_get_offset(sufile, curr),
+		     max - curr + 1);
+}
+
+static inline struct nilfs_sufile_header *
+nilfs_sufile_block_get_header(const struct inode *sufile,
+			      struct buffer_head *bh,
+			      void *kaddr)
+{
+	return kaddr + bh_offset(bh);
+}
+
+static struct nilfs_segment_usage *
+nilfs_sufile_block_get_segment_usage(const struct inode *sufile, __u64 segnum,
+				     struct buffer_head *bh, void *kaddr)
+{
+	return kaddr + bh_offset(bh) +
+		nilfs_sufile_get_offset(sufile, segnum) *
+		NILFS_MDT(sufile)->mi_entry_size;
+}
+
+static inline int nilfs_sufile_get_header_block(struct inode *sufile,
+						struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(sufile, 0, 0, NULL, bhp);
+}
+
+static inline int
+nilfs_sufile_get_segment_usage_block(struct inode *sufile, __u64 segnum,
+				     int create, struct buffer_head **bhp)
+{
+	return nilfs_mdt_get_block(sufile,
+				   nilfs_sufile_get_blkoff(sufile, segnum),
+				   create, NULL, bhp);
+}
+
+/**
+ * nilfs_sufile_alloc - allocate a segment
+ * @sufile: inode of segment usage file
+ * @segnump: pointer to segment number
+ *
+ * Description: nilfs_sufile_alloc() allocates a clean segment.
+ *
+ * Return Value: On success, 0 is returned and the segment number of the
+ * allocated segment is stored in the place pointed by @segnump. On error, one
+ * of the following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOSPC - No clean segment left.
+ */
+int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
+{
+	struct buffer_head *header_bh, *su_bh;
+	struct the_nilfs *nilfs;
+	struct nilfs_sufile_header *header;
+	struct nilfs_segment_usage *su;
+	size_t susz = NILFS_MDT(sufile)->mi_entry_size;
+	__u64 segnum, maxsegnum, last_alloc;
+	void *kaddr;
+	unsigned long nsegments, ncleansegs, nsus;
+	int ret, i, j;
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	nilfs = NILFS_MDT(sufile)->mi_nilfs;
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
+	ncleansegs = le64_to_cpu(header->sh_ncleansegs);
+	last_alloc = le64_to_cpu(header->sh_last_alloc);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nsegments = nilfs_sufile_get_nsegments(sufile);
+	segnum = last_alloc + 1;
+	maxsegnum = nsegments - 1;
+	for (i = 0; i < nsegments; i += nsus) {
+		if (segnum >= nsegments) {
+			/* wrap around */
+			segnum = 0;
+			maxsegnum = last_alloc;
+		}
+		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1,
+							   &su_bh);
+		if (ret < 0)
+			goto out_header;
+		kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+		su = nilfs_sufile_block_get_segment_usage(
+			sufile, segnum, su_bh, kaddr);
+
+		nsus = nilfs_sufile_segment_usages_in_block(
+			sufile, segnum, maxsegnum);
+		for (j = 0; j < nsus; j++, su = (void *)su + susz, segnum++) {
+			if (!nilfs_segment_usage_clean(su))
+				continue;
+			/* found a clean segment */
+			nilfs_segment_usage_set_dirty(su);
+			kunmap_atomic(kaddr, KM_USER0);
+
+			kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+			header = nilfs_sufile_block_get_header(
+				sufile, header_bh, kaddr);
+			le64_add_cpu(&header->sh_ncleansegs, -1);
+			le64_add_cpu(&header->sh_ndirtysegs, 1);
+			header->sh_last_alloc = cpu_to_le64(segnum);
+			kunmap_atomic(kaddr, KM_USER0);
+
+			nilfs_mdt_mark_buffer_dirty(header_bh);
+			nilfs_mdt_mark_buffer_dirty(su_bh);
+			nilfs_mdt_mark_dirty(sufile);
+			brelse(su_bh);
+			*segnump = segnum;
+			goto out_header;
+		}
+
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(su_bh);
+	}
+
+	/* no segments left */
+	ret = -ENOSPC;
+
+ out_header:
+	brelse(header_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_cancel_free -
+ * @sufile: inode of segment usage file
+ * @segnum: segment number
+ *
+ * Description:
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_sufile_cancel_free(struct inode *sufile, __u64 segnum)
+{
+	struct buffer_head *header_bh, *su_bh;
+	struct the_nilfs *nilfs;
+	struct nilfs_sufile_header *header;
+	struct nilfs_segment_usage *su;
+	void *kaddr;
+	int ret;
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	nilfs = NILFS_MDT(sufile)->mi_nilfs;
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+
+	ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &su_bh);
+	if (ret < 0)
+		goto out_header;
+
+	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	su = nilfs_sufile_block_get_segment_usage(
+		sufile, segnum, su_bh, kaddr);
+	if (unlikely(!nilfs_segment_usage_clean(su))) {
+		printk(KERN_WARNING "%s: segment %llu must be clean\n",
+		       __func__, (unsigned long long)segnum);
+		kunmap_atomic(kaddr, KM_USER0);
+		goto out_su_bh;
+	}
+	nilfs_segment_usage_set_dirty(su);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
+	le64_add_cpu(&header->sh_ncleansegs, -1);
+	le64_add_cpu(&header->sh_ndirtysegs, 1);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	nilfs_mdt_mark_buffer_dirty(header_bh);
+	nilfs_mdt_mark_buffer_dirty(su_bh);
+	nilfs_mdt_mark_dirty(sufile);
+
+ out_su_bh:
+	brelse(su_bh);
+ out_header:
+	brelse(header_bh);
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_freev - free segments
+ * @sufile: inode of segment usage file
+ * @segnum: array of segment numbers
+ * @nsegs: number of segments
+ *
+ * Description: nilfs_sufile_freev() frees segments specified by @segnum and
+ * @nsegs, which must have been returned by a previous call to
+ * nilfs_sufile_alloc().
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+#define NILFS_SUFILE_FREEV_PREALLOC	16
+int nilfs_sufile_freev(struct inode *sufile, __u64 *segnum, size_t nsegs)
+{
+	struct buffer_head *header_bh, **su_bh,
+		*su_bh_prealloc[NILFS_SUFILE_FREEV_PREALLOC];
+	struct the_nilfs *nilfs;
+	struct nilfs_sufile_header *header;
+	struct nilfs_segment_usage *su;
+	void *kaddr;
+	int ret, i;
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	nilfs = NILFS_MDT(sufile)->mi_nilfs;
+
+	/* prepare resources */
+	if (nsegs <= NILFS_SUFILE_FREEV_PREALLOC)
+		su_bh = su_bh_prealloc;
+	else {
+		su_bh = kmalloc(sizeof(*su_bh) * nsegs, GFP_NOFS);
+		if (su_bh == NULL) {
+			ret = -ENOMEM;
+			goto out_sem;
+		}
+	}
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_su_bh;
+	for (i = 0; i < nsegs; i++) {
+		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum[i],
+							   0, &su_bh[i]);
+		if (ret < 0)
+			goto out_bh;
+	}
+
+	/* free segments */
+	for (i = 0; i < nsegs; i++) {
+		kaddr = kmap_atomic(su_bh[i]->b_page, KM_USER0);
+		su = nilfs_sufile_block_get_segment_usage(
+			sufile, segnum[i], su_bh[i], kaddr);
+		WARN_ON(nilfs_segment_usage_error(su));
+		nilfs_segment_usage_set_clean(su);
+		kunmap_atomic(kaddr, KM_USER0);
+		nilfs_mdt_mark_buffer_dirty(su_bh[i]);
+	}
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
+	le64_add_cpu(&header->sh_ncleansegs, nsegs);
+	le64_add_cpu(&header->sh_ndirtysegs, -(u64)nsegs);
+	kunmap_atomic(kaddr, KM_USER0);
+	nilfs_mdt_mark_buffer_dirty(header_bh);
+	nilfs_mdt_mark_dirty(sufile);
+
+ out_bh:
+	for (i--; i >= 0; i--)
+		brelse(su_bh[i]);
+	brelse(header_bh);
+
+ out_su_bh:
+	if (su_bh != su_bh_prealloc)
+		kfree(su_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_free -
+ * @sufile:
+ * @segnum:
+ */
+int nilfs_sufile_free(struct inode *sufile, __u64 segnum)
+{
+	return nilfs_sufile_freev(sufile, &segnum, 1);
+}
+
+/**
+ * nilfs_sufile_get_segment_usage - get a segment usage
+ * @sufile: inode of segment usage file
+ * @segnum: segment number
+ * @sup: pointer to segment usage
+ * @bhp: pointer to buffer head
+ *
+ * Description: nilfs_sufile_get_segment_usage() acquires the segment usage
+ * specified by @segnum.
+ *
+ * Return Value: On success, 0 is returned, and the segment usage and the
+ * buffer head of the buffer on which the segment usage is located are stored
+ * in the place pointed by @sup and @bhp, respectively. On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EINVAL - Invalid segment usage number.
+ */
+int nilfs_sufile_get_segment_usage(struct inode *sufile, __u64 segnum,
+				   struct nilfs_segment_usage **sup,
+				   struct buffer_head **bhp)
+{
+	struct buffer_head *bh;
+	struct nilfs_segment_usage *su;
+	void *kaddr;
+	int ret;
+
+	/* segnum is 0 origin */
+	if (segnum >= nilfs_sufile_get_nsegments(sufile))
+		return -EINVAL;
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+	ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1, &bh);
+	if (ret < 0)
+		goto out_sem;
+	kaddr = kmap(bh->b_page);
+	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
+	if (nilfs_segment_usage_error(su)) {
+		kunmap(bh->b_page);
+		brelse(bh);
+		ret = -EINVAL;
+		goto out_sem;
+	}
+
+	if (sup != NULL)
+		*sup = su;
+	*bhp = bh;
+
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_put_segment_usage - put a segment usage
+ * @sufile: inode of segment usage file
+ * @segnum: segment number
+ * @bh: buffer head
+ *
+ * Description: nilfs_sufile_put_segment_usage() releases the segment usage
+ * specified by @segnum. @bh must be the buffer head which have been returned
+ * by a previous call to nilfs_sufile_get_segment_usage() with @segnum.
+ */
+void nilfs_sufile_put_segment_usage(struct inode *sufile, __u64 segnum,
+				    struct buffer_head *bh)
+{
+	kunmap(bh->b_page);
+	brelse(bh);
+}
+
+/**
+ * nilfs_sufile_get_stat - get segment usage statistics
+ * @sufile: inode of segment usage file
+ * @stat: pointer to a structure of segment usage statistics
+ *
+ * Description: nilfs_sufile_get_stat() returns information about segment
+ * usage.
+ *
+ * Return Value: On success, 0 is returned, and segment usage information is
+ * stored in the place pointed by @stat. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_sufile_get_stat(struct inode *sufile, struct nilfs_sustat *sustat)
+{
+	struct buffer_head *header_bh;
+	struct nilfs_sufile_header *header;
+	struct the_nilfs *nilfs = NILFS_MDT(sufile)->mi_nilfs;
+	void *kaddr;
+	int ret;
+
+	down_read(&NILFS_MDT(sufile)->mi_sem);
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
+	sustat->ss_nsegs = nilfs_sufile_get_nsegments(sufile);
+	sustat->ss_ncleansegs = le64_to_cpu(header->sh_ncleansegs);
+	sustat->ss_ndirtysegs = le64_to_cpu(header->sh_ndirtysegs);
+	sustat->ss_ctime = nilfs->ns_ctime;
+	sustat->ss_nongc_ctime = nilfs->ns_nongc_ctime;
+	spin_lock(&nilfs->ns_last_segment_lock);
+	sustat->ss_prot_seq = nilfs->ns_prot_seq;
+	spin_unlock(&nilfs->ns_last_segment_lock);
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(header_bh);
+
+ out_sem:
+	up_read(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_get_ncleansegs - get the number of clean segments
+ * @sufile: inode of segment usage file
+ * @nsegsp: pointer to the number of clean segments
+ *
+ * Description: nilfs_sufile_get_ncleansegs() acquires the number of clean
+ * segments.
+ *
+ * Return Value: On success, 0 is returned and the number of clean segments is
+ * stored in the place pointed by @nsegsp. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_sufile_get_ncleansegs(struct inode *sufile, unsigned long *nsegsp)
+{
+	struct nilfs_sustat sustat;
+	int ret;
+
+	ret = nilfs_sufile_get_stat(sufile, &sustat);
+	if (ret == 0)
+		*nsegsp = sustat.ss_ncleansegs;
+	return ret;
+}
+
+/**
+ * nilfs_sufile_set_error - mark a segment as erroneous
+ * @sufile: inode of segment usage file
+ * @segnum: segment number
+ *
+ * Description: nilfs_sufile_set_error() marks the segment specified by
+ * @segnum as erroneous. The error segment will never be used again.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EINVAL - Invalid segment usage number.
+ */
+int nilfs_sufile_set_error(struct inode *sufile, __u64 segnum)
+{
+	struct buffer_head *header_bh, *su_bh;
+	struct nilfs_segment_usage *su;
+	struct nilfs_sufile_header *header;
+	void *kaddr;
+	int ret;
+
+	if (unlikely(segnum >= nilfs_sufile_get_nsegments(sufile))) {
+		printk(KERN_WARNING "%s: invalid segment number: %llu\n",
+		       __func__, (unsigned long long)segnum);
+		return -EINVAL;
+	}
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+	ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &su_bh);
+	if (ret < 0)
+		goto out_header;
+
+	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
+	if (nilfs_segment_usage_error(su)) {
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(su_bh);
+		goto out_header;
+	}
+
+	nilfs_segment_usage_set_error(su);
+	kunmap_atomic(kaddr, KM_USER0);
+	brelse(su_bh);
+
+	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
+	le64_add_cpu(&header->sh_ndirtysegs, -1);
+	kunmap_atomic(kaddr, KM_USER0);
+	nilfs_mdt_mark_buffer_dirty(header_bh);
+	nilfs_mdt_mark_buffer_dirty(su_bh);
+	nilfs_mdt_mark_dirty(sufile);
+	brelse(su_bh);
+
+ out_header:
+	brelse(header_bh);
+
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_get_suinfo -
+ * @sufile: inode of segment usage file
+ * @segnum: segment number to start looking
+ * @si: array of suinfo
+ * @nsi: size of suinfo array
+ *
+ * Description:
+ *
+ * Return Value: On success, 0 is returned and .... On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum,
+				struct nilfs_suinfo *si, size_t nsi)
+{
+	struct buffer_head *su_bh;
+	struct nilfs_segment_usage *su;
+	size_t susz = NILFS_MDT(sufile)->mi_entry_size;
+	struct the_nilfs *nilfs = NILFS_MDT(sufile)->mi_nilfs;
+	void *kaddr;
+	unsigned long nsegs, segusages_per_block;
+	ssize_t n;
+	int ret, i, j;
+
+	down_read(&NILFS_MDT(sufile)->mi_sem);
+
+	segusages_per_block = nilfs_sufile_segment_usages_per_block(sufile);
+	nsegs = min_t(unsigned long,
+		      nilfs_sufile_get_nsegments(sufile) - segnum,
+		      nsi);
+	for (i = 0; i < nsegs; i += n, segnum += n) {
+		n = min_t(unsigned long,
+			  segusages_per_block -
+				  nilfs_sufile_get_offset(sufile, segnum),
+			  nsegs - i);
+		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
+							   &su_bh);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				goto out;
+			/* hole */
+			memset(&si[i], 0, sizeof(struct nilfs_suinfo) * n);
+			continue;
+		}
+
+		kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+		su = nilfs_sufile_block_get_segment_usage(
+			sufile, segnum, su_bh, kaddr);
+		for (j = 0; j < n; j++, su = (void *)su + susz) {
+			si[i + j].sui_lastmod = le64_to_cpu(su->su_lastmod);
+			si[i + j].sui_nblocks = le32_to_cpu(su->su_nblocks);
+			si[i + j].sui_flags = le32_to_cpu(su->su_flags) &
+				~(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
+			if (nilfs_segment_is_active(nilfs, segnum + i + j))
+				si[i + j].sui_flags |=
+					(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
+		}
+		kunmap_atomic(kaddr, KM_USER0);
+		brelse(su_bh);
+	}
+	ret = nsegs;
+
+ out:
+	up_read(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
diff --git a/fs/nilfs2/sufile.h b/fs/nilfs2/sufile.h
new file mode 100644
index 00000000000..d595f33a768
--- /dev/null
+++ b/fs/nilfs2/sufile.h
@@ -0,0 +1,54 @@
+/*
+ * sufile.h - NILFS segment usage file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#ifndef _NILFS_SUFILE_H
+#define _NILFS_SUFILE_H
+
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/nilfs2_fs.h>
+#include "mdt.h"
+
+#define NILFS_SUFILE_GFP	NILFS_MDT_GFP
+
+static inline unsigned long nilfs_sufile_get_nsegments(struct inode *sufile)
+{
+	return NILFS_MDT(sufile)->mi_nilfs->ns_nsegments;
+}
+
+int nilfs_sufile_alloc(struct inode *, __u64 *);
+int nilfs_sufile_cancel_free(struct inode *, __u64);
+int nilfs_sufile_freev(struct inode *, __u64 *, size_t);
+int nilfs_sufile_free(struct inode *, __u64);
+int nilfs_sufile_get_segment_usage(struct inode *, __u64,
+				   struct nilfs_segment_usage **,
+				   struct buffer_head **);
+void nilfs_sufile_put_segment_usage(struct inode *, __u64,
+				    struct buffer_head *);
+int nilfs_sufile_get_stat(struct inode *, struct nilfs_sustat *);
+int nilfs_sufile_get_ncleansegs(struct inode *, unsigned long *);
+int nilfs_sufile_set_error(struct inode *, __u64);
+ssize_t nilfs_sufile_get_suinfo(struct inode *, __u64, struct nilfs_suinfo *,
+				size_t);
+
+
+#endif	/* _NILFS_SUFILE_H */
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
new file mode 100644
index 00000000000..e117e1ea9bf
--- /dev/null
+++ b/fs/nilfs2/super.c
@@ -0,0 +1,1323 @@
+/*
+ * super.c - NILFS module and super block management.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ */
+/*
+ *  linux/fs/ext2/super.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/inode.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/parser.h>
+#include <linux/random.h>
+#include <linux/crc32.h>
+#include <linux/smp_lock.h>
+#include <linux/vfs.h>
+#include <linux/writeback.h>
+#include <linux/kobject.h>
+#include <linux/exportfs.h>
+#include "nilfs.h"
+#include "mdt.h"
+#include "alloc.h"
+#include "page.h"
+#include "cpfile.h"
+#include "ifile.h"
+#include "dat.h"
+#include "segment.h"
+#include "segbuf.h"
+
+MODULE_AUTHOR("NTT Corp.");
+MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
+		   "(NILFS)");
+MODULE_VERSION(NILFS_VERSION);
+MODULE_LICENSE("GPL");
+
+static int nilfs_remount(struct super_block *sb, int *flags, char *data);
+static int test_exclusive_mount(struct file_system_type *fs_type,
+				struct block_device *bdev, int flags);
+
+/**
+ * nilfs_error() - report failure condition on a filesystem
+ *
+ * nilfs_error() sets an ERROR_FS flag on the superblock as well as
+ * reporting an error message.  It should be called when NILFS detects
+ * incoherences or defects of meta data on disk.  As for sustainable
+ * errors such as a single-shot I/O error, nilfs_warning() or the printk()
+ * function should be used instead.
+ *
+ * The segment constructor must not call this function because it can
+ * kill itself.
+ */
+void nilfs_error(struct super_block *sb, const char *function,
+		 const char *fmt, ...)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	va_list args;
+
+	va_start(args, fmt);
+	printk(KERN_CRIT "NILFS error (device %s): %s: ", sb->s_id, function);
+	vprintk(fmt, args);
+	printk("\n");
+	va_end(args);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		struct the_nilfs *nilfs = sbi->s_nilfs;
+
+		if (!nilfs_test_opt(sbi, ERRORS_CONT))
+			nilfs_detach_segment_constructor(sbi);
+
+		down_write(&nilfs->ns_sem);
+		if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
+			nilfs->ns_mount_state |= NILFS_ERROR_FS;
+			nilfs->ns_sbp[0]->s_state |=
+				cpu_to_le16(NILFS_ERROR_FS);
+			nilfs_commit_super(sbi, 1);
+		}
+		up_write(&nilfs->ns_sem);
+
+		if (nilfs_test_opt(sbi, ERRORS_RO)) {
+			printk(KERN_CRIT "Remounting filesystem read-only\n");
+			sb->s_flags |= MS_RDONLY;
+		}
+	}
+
+	if (nilfs_test_opt(sbi, ERRORS_PANIC))
+		panic("NILFS (device %s): panic forced after error\n",
+		      sb->s_id);
+}
+
+void nilfs_warning(struct super_block *sb, const char *function,
+		   const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	printk(KERN_WARNING "NILFS warning (device %s): %s: ",
+	       sb->s_id, function);
+	vprintk(fmt, args);
+	printk("\n");
+	va_end(args);
+}
+
+static struct kmem_cache *nilfs_inode_cachep;
+
+struct inode *nilfs_alloc_inode(struct super_block *sb)
+{
+	struct nilfs_inode_info *ii;
+
+	ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
+	if (!ii)
+		return NULL;
+	ii->i_bh = NULL;
+	ii->i_state = 0;
+	ii->vfs_inode.i_version = 1;
+	nilfs_btnode_cache_init(&ii->i_btnode_cache);
+	return &ii->vfs_inode;
+}
+
+void nilfs_destroy_inode(struct inode *inode)
+{
+	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
+}
+
+static void init_once(void *obj)
+{
+	struct nilfs_inode_info *ii = obj;
+
+	INIT_LIST_HEAD(&ii->i_dirty);
+#ifdef CONFIG_NILFS_XATTR
+	init_rwsem(&ii->xattr_sem);
+#endif
+	nilfs_btnode_cache_init_once(&ii->i_btnode_cache);
+	ii->i_bmap = (struct nilfs_bmap *)&ii->i_bmap_union;
+	inode_init_once(&ii->vfs_inode);
+}
+
+static int nilfs_init_inode_cache(void)
+{
+	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
+					       sizeof(struct nilfs_inode_info),
+					       0, SLAB_RECLAIM_ACCOUNT,
+					       init_once);
+
+	return (nilfs_inode_cachep == NULL) ? -ENOMEM : 0;
+}
+
+static inline void nilfs_destroy_inode_cache(void)
+{
+	kmem_cache_destroy(nilfs_inode_cachep);
+}
+
+static void nilfs_clear_inode(struct inode *inode)
+{
+	struct nilfs_inode_info *ii = NILFS_I(inode);
+
+#ifdef CONFIG_NILFS_POSIX_ACL
+	if (ii->i_acl && ii->i_acl != NILFS_ACL_NOT_CACHED) {
+		posix_acl_release(ii->i_acl);
+		ii->i_acl = NILFS_ACL_NOT_CACHED;
+	}
+	if (ii->i_default_acl && ii->i_default_acl != NILFS_ACL_NOT_CACHED) {
+		posix_acl_release(ii->i_default_acl);
+		ii->i_default_acl = NILFS_ACL_NOT_CACHED;
+	}
+#endif
+	/*
+	 * Free resources allocated in nilfs_read_inode(), here.
+	 */
+	BUG_ON(!list_empty(&ii->i_dirty));
+	brelse(ii->i_bh);
+	ii->i_bh = NULL;
+
+	if (test_bit(NILFS_I_BMAP, &ii->i_state))
+		nilfs_bmap_clear(ii->i_bmap);
+
+	nilfs_btnode_cache_clear(&ii->i_btnode_cache);
+}
+
+static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int err;
+	int barrier_done = 0;
+
+	if (nilfs_test_opt(sbi, BARRIER)) {
+		set_buffer_ordered(nilfs->ns_sbh[0]);
+		barrier_done = 1;
+	}
+ retry:
+	set_buffer_dirty(nilfs->ns_sbh[0]);
+	err = sync_dirty_buffer(nilfs->ns_sbh[0]);
+	if (err == -EOPNOTSUPP && barrier_done) {
+		nilfs_warning(sbi->s_super, __func__,
+			      "barrier-based sync failed. "
+			      "disabling barriers\n");
+		nilfs_clear_opt(sbi, BARRIER);
+		barrier_done = 0;
+		clear_buffer_ordered(nilfs->ns_sbh[0]);
+		goto retry;
+	}
+	if (unlikely(err)) {
+		printk(KERN_ERR
+		       "NILFS: unable to write superblock (err=%d)\n", err);
+		if (err == -EIO && nilfs->ns_sbh[1]) {
+			nilfs_fall_back_super_block(nilfs);
+			goto retry;
+		}
+	} else {
+		struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
+
+		/*
+		 * The latest segment becomes trailable from the position
+		 * written in superblock.
+		 */
+		clear_nilfs_discontinued(nilfs);
+
+		/* update GC protection for recent segments */
+		if (nilfs->ns_sbh[1]) {
+			sbp = NULL;
+			if (dupsb) {
+				set_buffer_dirty(nilfs->ns_sbh[1]);
+				if (!sync_dirty_buffer(nilfs->ns_sbh[1]))
+					sbp = nilfs->ns_sbp[1];
+			}
+		}
+		if (sbp) {
+			spin_lock(&nilfs->ns_last_segment_lock);
+			nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
+			spin_unlock(&nilfs->ns_last_segment_lock);
+		}
+	}
+
+	return err;
+}
+
+int nilfs_commit_super(struct nilfs_sb_info *sbi, int dupsb)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+	sector_t nfreeblocks;
+	time_t t;
+	int err;
+
+	/* nilfs->sem must be locked by the caller. */
+	if (sbp[0]->s_magic != NILFS_SUPER_MAGIC) {
+		if (sbp[1] && sbp[1]->s_magic == NILFS_SUPER_MAGIC)
+			nilfs_swap_super_block(nilfs);
+		else {
+			printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
+			       sbi->s_super->s_id);
+			return -EIO;
+		}
+	}
+	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
+	if (unlikely(err)) {
+		printk(KERN_ERR "NILFS: failed to count free blocks\n");
+		return err;
+	}
+	spin_lock(&nilfs->ns_last_segment_lock);
+	sbp[0]->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
+	sbp[0]->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
+	sbp[0]->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
+	spin_unlock(&nilfs->ns_last_segment_lock);
+
+	t = get_seconds();
+	nilfs->ns_sbwtime[0] = t;
+	sbp[0]->s_free_blocks_count = cpu_to_le64(nfreeblocks);
+	sbp[0]->s_wtime = cpu_to_le64(t);
+	sbp[0]->s_sum = 0;
+	sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
+					     (unsigned char *)sbp[0],
+					     nilfs->ns_sbsize));
+	if (dupsb && sbp[1]) {
+		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
+		nilfs->ns_sbwtime[1] = t;
+	}
+	sbi->s_super->s_dirt = 0;
+	return nilfs_sync_super(sbi, dupsb);
+}
+
+static void nilfs_put_super(struct super_block *sb)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+
+	nilfs_detach_segment_constructor(sbi);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		down_write(&nilfs->ns_sem);
+		nilfs->ns_sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
+		nilfs_commit_super(sbi, 1);
+		up_write(&nilfs->ns_sem);
+	}
+
+	nilfs_detach_checkpoint(sbi);
+	put_nilfs(sbi->s_nilfs);
+	sbi->s_super = NULL;
+	sb->s_fs_info = NULL;
+	kfree(sbi);
+}
+
+/**
+ * nilfs_write_super - write super block(s) of NILFS
+ * @sb: super_block
+ *
+ * nilfs_write_super() gets a fs-dependent lock, writes super block(s), and
+ * clears s_dirt.  This function is called in the section protected by
+ * lock_super().
+ *
+ * The s_dirt flag is managed by each filesystem and we protect it by ns_sem
+ * of the struct the_nilfs.  Lock order must be as follows:
+ *
+ *   1. lock_super()
+ *   2.    down_write(&nilfs->ns_sem)
+ *
+ * Inside NILFS, locking ns_sem is enough to protect s_dirt and the buffer
+ * of the super block (nilfs->ns_sbp[]).
+ *
+ * In most cases, VFS functions call lock_super() before calling these
+ * methods.  So we must be careful not to bring on deadlocks when using
+ * lock_super();  see generic_shutdown_super(), write_super(), and so on.
+ *
+ * Note that order of lock_kernel() and lock_super() depends on contexts
+ * of VFS.  We should also note that lock_kernel() can be used in its
+ * protective section and only the outermost one has an effect.
+ */
+static void nilfs_write_super(struct super_block *sb)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+
+	down_write(&nilfs->ns_sem);
+	if (!(sb->s_flags & MS_RDONLY)) {
+		struct nilfs_super_block **sbp = nilfs->ns_sbp;
+		u64 t = get_seconds();
+		int dupsb;
+
+		if (!nilfs_discontinued(nilfs) && t >= nilfs->ns_sbwtime[0] &&
+		    t < nilfs->ns_sbwtime[0] + NILFS_SB_FREQ) {
+			up_write(&nilfs->ns_sem);
+			return;
+		}
+		dupsb = sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
+		nilfs_commit_super(sbi, dupsb);
+	}
+	sb->s_dirt = 0;
+	up_write(&nilfs->ns_sem);
+}
+
+static int nilfs_sync_fs(struct super_block *sb, int wait)
+{
+	int err = 0;
+
+	/* This function is called when super block should be written back */
+	if (wait)
+		err = nilfs_construct_segment(sb);
+	return err;
+}
+
+int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct nilfs_checkpoint *raw_cp;
+	struct buffer_head *bh_cp;
+	int err;
+
+	down_write(&nilfs->ns_sem);
+	list_add(&sbi->s_list, &nilfs->ns_supers);
+	up_write(&nilfs->ns_sem);
+
+	sbi->s_ifile = nilfs_mdt_new(
+		nilfs, sbi->s_super, NILFS_IFILE_INO, NILFS_IFILE_GFP);
+	if (!sbi->s_ifile)
+		return -ENOMEM;
+
+	err = nilfs_palloc_init_blockgroup(sbi->s_ifile, nilfs->ns_inode_size);
+	if (unlikely(err))
+		goto failed;
+
+	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
+					  &bh_cp);
+	if (unlikely(err)) {
+		if (err == -ENOENT || err == -EINVAL) {
+			printk(KERN_ERR
+			       "NILFS: Invalid checkpoint "
+			       "(checkpoint number=%llu)\n",
+			       (unsigned long long)cno);
+			err = -EINVAL;
+		}
+		goto failed;
+	}
+	err = nilfs_read_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode);
+	if (unlikely(err))
+		goto failed_bh;
+	atomic_set(&sbi->s_inodes_count, le64_to_cpu(raw_cp->cp_inodes_count));
+	atomic_set(&sbi->s_blocks_count, le64_to_cpu(raw_cp->cp_blocks_count));
+
+	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
+	return 0;
+
+ failed_bh:
+	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
+ failed:
+	nilfs_mdt_destroy(sbi->s_ifile);
+	sbi->s_ifile = NULL;
+
+	down_write(&nilfs->ns_sem);
+	list_del_init(&sbi->s_list);
+	up_write(&nilfs->ns_sem);
+
+	return err;
+}
+
+void nilfs_detach_checkpoint(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+
+	nilfs_mdt_clear(sbi->s_ifile);
+	nilfs_mdt_destroy(sbi->s_ifile);
+	sbi->s_ifile = NULL;
+	down_write(&nilfs->ns_sem);
+	list_del_init(&sbi->s_list);
+	up_write(&nilfs->ns_sem);
+}
+
+static int nilfs_mark_recovery_complete(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int err = 0;
+
+	down_write(&nilfs->ns_sem);
+	if (!(nilfs->ns_mount_state & NILFS_VALID_FS)) {
+		nilfs->ns_mount_state |= NILFS_VALID_FS;
+		err = nilfs_commit_super(sbi, 1);
+		if (likely(!err))
+			printk(KERN_INFO "NILFS: recovery complete.\n");
+	}
+	up_write(&nilfs->ns_sem);
+	return err;
+}
+
+static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	unsigned long long blocks;
+	unsigned long overhead;
+	unsigned long nrsvblocks;
+	sector_t nfreeblocks;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	int err;
+
+	/*
+	 * Compute all of the segment blocks
+	 *
+	 * The blocks before first segment and after last segment
+	 * are excluded.
+	 */
+	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
+		- nilfs->ns_first_data_block;
+	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
+
+	/*
+	 * Compute the overhead
+	 *
+	 * When distributing meta data blocks outside semgent structure,
+	 * We must count them as the overhead.
+	 */
+	overhead = 0;
+
+	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
+	if (unlikely(err))
+		return err;
+
+	buf->f_type = NILFS_SUPER_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_blocks = blocks - overhead;
+	buf->f_bfree = nfreeblocks;
+	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
+		(buf->f_bfree - nrsvblocks) : 0;
+	buf->f_files = atomic_read(&sbi->s_inodes_count);
+	buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
+	buf->f_namelen = NILFS_NAME_LEN;
+	return 0;
+}
+
+static struct super_operations nilfs_sops = {
+	.alloc_inode    = nilfs_alloc_inode,
+	.destroy_inode  = nilfs_destroy_inode,
+	.dirty_inode    = nilfs_dirty_inode,
+	/* .write_inode    = nilfs_write_inode, */
+	/* .put_inode      = nilfs_put_inode, */
+	/* .drop_inode	  = nilfs_drop_inode, */
+	.delete_inode   = nilfs_delete_inode,
+	.put_super      = nilfs_put_super,
+	.write_super    = nilfs_write_super,
+	.sync_fs        = nilfs_sync_fs,
+	/* .write_super_lockfs */
+	/* .unlockfs */
+	.statfs         = nilfs_statfs,
+	.remount_fs     = nilfs_remount,
+	.clear_inode    = nilfs_clear_inode,
+	/* .umount_begin */
+	/* .show_options */
+};
+
+static struct inode *
+nilfs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation)
+{
+	struct inode *inode;
+
+	if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO &&
+	    ino != NILFS_SKETCH_INO)
+		return ERR_PTR(-ESTALE);
+
+	inode = nilfs_iget(sb, ino);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+	if (generation && inode->i_generation != generation) {
+		iput(inode);
+		return ERR_PTR(-ESTALE);
+	}
+
+	return inode;
+}
+
+static struct dentry *
+nilfs_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len,
+		   int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    nilfs_nfs_get_inode);
+}
+
+static struct dentry *
+nilfs_fh_to_parent(struct super_block *sb, struct fid *fid, int fh_len,
+		   int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    nilfs_nfs_get_inode);
+}
+
+static struct export_operations nilfs_export_ops = {
+	.fh_to_dentry = nilfs_fh_to_dentry,
+	.fh_to_parent = nilfs_fh_to_parent,
+	.get_parent = nilfs_get_parent,
+};
+
+enum {
+	Opt_err_cont, Opt_err_panic, Opt_err_ro,
+	Opt_barrier, Opt_snapshot, Opt_order,
+	Opt_err,
+};
+
+static match_table_t tokens = {
+	{Opt_err_cont, "errors=continue"},
+	{Opt_err_panic, "errors=panic"},
+	{Opt_err_ro, "errors=remount-ro"},
+	{Opt_barrier, "barrier=%s"},
+	{Opt_snapshot, "cp=%u"},
+	{Opt_order, "order=%s"},
+	{Opt_err, NULL}
+};
+
+static int match_bool(substring_t *s, int *result)
+{
+	int len = s->to - s->from;
+
+	if (strncmp(s->from, "on", len) == 0)
+		*result = 1;
+	else if (strncmp(s->from, "off", len) == 0)
+		*result = 0;
+	else
+		return 1;
+	return 0;
+}
+
+static int parse_options(char *options, struct super_block *sb)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+
+	if (!options)
+		return 1;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_barrier:
+			if (match_bool(&args[0], &option))
+				return 0;
+			if (option)
+				nilfs_set_opt(sbi, BARRIER);
+			else
+				nilfs_clear_opt(sbi, BARRIER);
+			break;
+		case Opt_order:
+			if (strcmp(args[0].from, "relaxed") == 0)
+				/* Ordered data semantics */
+				nilfs_clear_opt(sbi, STRICT_ORDER);
+			else if (strcmp(args[0].from, "strict") == 0)
+				/* Strict in-order semantics */
+				nilfs_set_opt(sbi, STRICT_ORDER);
+			else
+				return 0;
+			break;
+		case Opt_err_panic:
+			nilfs_write_opt(sbi, ERROR_MODE, ERRORS_PANIC);
+			break;
+		case Opt_err_ro:
+			nilfs_write_opt(sbi, ERROR_MODE, ERRORS_RO);
+			break;
+		case Opt_err_cont:
+			nilfs_write_opt(sbi, ERROR_MODE, ERRORS_CONT);
+			break;
+		case Opt_snapshot:
+			if (match_int(&args[0], &option) || option <= 0)
+				return 0;
+			if (!(sb->s_flags & MS_RDONLY))
+				return 0;
+			sbi->s_snapshot_cno = option;
+			nilfs_set_opt(sbi, SNAPSHOT);
+			break;
+		default:
+			printk(KERN_ERR
+			       "NILFS: Unrecognized mount option \"%s\"\n", p);
+			return 0;
+		}
+	}
+	return 1;
+}
+
+static inline void
+nilfs_set_default_options(struct nilfs_sb_info *sbi,
+			  struct nilfs_super_block *sbp)
+{
+	sbi->s_mount_opt =
+		NILFS_MOUNT_ERRORS_CONT | NILFS_MOUNT_BARRIER;
+}
+
+static int nilfs_setup_super(struct nilfs_sb_info *sbi)
+{
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
+	int max_mnt_count = le16_to_cpu(sbp->s_max_mnt_count);
+	int mnt_count = le16_to_cpu(sbp->s_mnt_count);
+
+	/* nilfs->sem must be locked by the caller. */
+	if (!(nilfs->ns_mount_state & NILFS_VALID_FS)) {
+		printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
+	} else if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
+		printk(KERN_WARNING
+		       "NILFS warning: mounting fs with errors\n");
+#if 0
+	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
+		printk(KERN_WARNING
+		       "NILFS warning: maximal mount count reached\n");
+#endif
+	}
+	if (!max_mnt_count)
+		sbp->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
+
+	sbp->s_mnt_count = cpu_to_le16(mnt_count + 1);
+	sbp->s_state = cpu_to_le16(le16_to_cpu(sbp->s_state) & ~NILFS_VALID_FS);
+	sbp->s_mtime = cpu_to_le64(get_seconds());
+	return nilfs_commit_super(sbi, 1);
+}
+
+struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
+						 u64 pos, int blocksize,
+						 struct buffer_head **pbh)
+{
+	unsigned long long sb_index = pos;
+	unsigned long offset;
+
+	offset = do_div(sb_index, blocksize);
+	*pbh = sb_bread(sb, sb_index);
+	if (!*pbh)
+		return NULL;
+	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
+}
+
+int nilfs_store_magic_and_option(struct super_block *sb,
+				 struct nilfs_super_block *sbp,
+				 char *data)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+
+	sb->s_magic = le16_to_cpu(sbp->s_magic);
+
+	/* FS independent flags */
+#ifdef NILFS_ATIME_DISABLE
+	sb->s_flags |= MS_NOATIME;
+#endif
+
+	nilfs_set_default_options(sbi, sbp);
+
+	sbi->s_resuid = le16_to_cpu(sbp->s_def_resuid);
+	sbi->s_resgid = le16_to_cpu(sbp->s_def_resgid);
+	sbi->s_interval = le32_to_cpu(sbp->s_c_interval);
+	sbi->s_watermark = le32_to_cpu(sbp->s_c_block_max);
+
+	return !parse_options(data, sb) ? -EINVAL : 0 ;
+}
+
+/**
+ * nilfs_fill_super() - initialize a super block instance
+ * @sb: super_block
+ * @data: mount options
+ * @silent: silent mode flag
+ * @nilfs: the_nilfs struct
+ *
+ * This function is called exclusively by bd_mount_mutex.
+ * So, the recovery process is protected from other simultaneous mounts.
+ */
+static int
+nilfs_fill_super(struct super_block *sb, void *data, int silent,
+		 struct the_nilfs *nilfs)
+{
+	struct nilfs_sb_info *sbi;
+	struct inode *root;
+	__u64 cno;
+	int err;
+
+	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+
+	sb->s_fs_info = sbi;
+
+	get_nilfs(nilfs);
+	sbi->s_nilfs = nilfs;
+	sbi->s_super = sb;
+
+	err = init_nilfs(nilfs, sbi, (char *)data);
+	if (err)
+		goto failed_sbi;
+
+	spin_lock_init(&sbi->s_inode_lock);
+	INIT_LIST_HEAD(&sbi->s_dirty_files);
+	INIT_LIST_HEAD(&sbi->s_list);
+
+	/*
+	 * Following initialization is overlapped because
+	 * nilfs_sb_info structure has been cleared at the beginning.
+	 * But we reserve them to keep our interest and make ready
+	 * for the future change.
+	 */
+	get_random_bytes(&sbi->s_next_generation,
+			 sizeof(sbi->s_next_generation));
+	spin_lock_init(&sbi->s_next_gen_lock);
+
+	sb->s_op = &nilfs_sops;
+	sb->s_export_op = &nilfs_export_ops;
+	sb->s_root = NULL;
+	sb->s_time_gran = 1;
+
+	if (!nilfs_loaded(nilfs)) {
+		err = load_nilfs(nilfs, sbi);
+		if (err)
+			goto failed_sbi;
+	}
+	cno = nilfs_last_cno(nilfs);
+
+	if (sb->s_flags & MS_RDONLY) {
+		if (nilfs_test_opt(sbi, SNAPSHOT)) {
+			err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
+						       sbi->s_snapshot_cno);
+			if (err < 0)
+				goto failed_sbi;
+			if (!err) {
+				printk(KERN_ERR
+				       "NILFS: The specified checkpoint is "
+				       "not a snapshot "
+				       "(checkpoint number=%llu).\n",
+				       (unsigned long long)sbi->s_snapshot_cno);
+				err = -EINVAL;
+				goto failed_sbi;
+			}
+			cno = sbi->s_snapshot_cno;
+		} else
+			/* Read-only mount */
+			sbi->s_snapshot_cno = cno;
+	}
+
+	err = nilfs_attach_checkpoint(sbi, cno);
+	if (err) {
+		printk(KERN_ERR "NILFS: error loading a checkpoint"
+		       " (checkpoint number=%llu).\n", (unsigned long long)cno);
+		goto failed_sbi;
+	}
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		err = nilfs_attach_segment_constructor(sbi);
+		if (err)
+			goto failed_checkpoint;
+	}
+
+	root = nilfs_iget(sb, NILFS_ROOT_INO);
+	if (IS_ERR(root)) {
+		printk(KERN_ERR "NILFS: get root inode failed\n");
+		err = PTR_ERR(root);
+		goto failed_segctor;
+	}
+	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
+		iput(root);
+		printk(KERN_ERR "NILFS: corrupt root inode.\n");
+		err = -EINVAL;
+		goto failed_segctor;
+	}
+	sb->s_root = d_alloc_root(root);
+	if (!sb->s_root) {
+		iput(root);
+		printk(KERN_ERR "NILFS: get root dentry failed\n");
+		err = -ENOMEM;
+		goto failed_segctor;
+	}
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		down_write(&nilfs->ns_sem);
+		nilfs_setup_super(sbi);
+		up_write(&nilfs->ns_sem);
+	}
+
+	err = nilfs_mark_recovery_complete(sbi);
+	if (unlikely(err)) {
+		printk(KERN_ERR "NILFS: recovery failed.\n");
+		goto failed_root;
+	}
+
+	return 0;
+
+ failed_root:
+	dput(sb->s_root);
+	sb->s_root = NULL;
+
+ failed_segctor:
+	nilfs_detach_segment_constructor(sbi);
+
+ failed_checkpoint:
+	nilfs_detach_checkpoint(sbi);
+
+ failed_sbi:
+	put_nilfs(nilfs);
+	sb->s_fs_info = NULL;
+	kfree(sbi);
+	return err;
+}
+
+static int nilfs_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct nilfs_super_block *sbp;
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	unsigned long old_sb_flags;
+	struct nilfs_mount_options old_opts;
+	int err;
+
+	old_sb_flags = sb->s_flags;
+	old_opts.mount_opt = sbi->s_mount_opt;
+	old_opts.snapshot_cno = sbi->s_snapshot_cno;
+
+	if (!parse_options(data, sb)) {
+		err = -EINVAL;
+		goto restore_opts;
+	}
+	sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
+
+	if ((*flags & MS_RDONLY) &&
+	    sbi->s_snapshot_cno != old_opts.snapshot_cno) {
+		printk(KERN_WARNING "NILFS (device %s): couldn't "
+		       "remount to a different snapshot. \n",
+		       sb->s_id);
+		err = -EINVAL;
+		goto restore_opts;
+	}
+
+	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
+		goto out;
+	if (*flags & MS_RDONLY) {
+		/* Shutting down the segment constructor */
+		nilfs_detach_segment_constructor(sbi);
+		sb->s_flags |= MS_RDONLY;
+
+		sbi->s_snapshot_cno = nilfs_last_cno(nilfs);
+		/* nilfs_set_opt(sbi, SNAPSHOT); */
+
+		/*
+		 * Remounting a valid RW partition RDONLY, so set
+		 * the RDONLY flag and then mark the partition as valid again.
+		 */
+		down_write(&nilfs->ns_sem);
+		sbp = nilfs->ns_sbp[0];
+		if (!(sbp->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
+		    (nilfs->ns_mount_state & NILFS_VALID_FS))
+			sbp->s_state = cpu_to_le16(nilfs->ns_mount_state);
+		sbp->s_mtime = cpu_to_le64(get_seconds());
+		nilfs_commit_super(sbi, 1);
+		up_write(&nilfs->ns_sem);
+	} else {
+		/*
+		 * Mounting a RDONLY partition read-write, so reread and
+		 * store the current valid flag.  (It may have been changed
+		 * by fsck since we originally mounted the partition.)
+		 */
+		down(&sb->s_bdev->bd_mount_sem);
+		/* Check existing RW-mount */
+		if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {
+			printk(KERN_WARNING "NILFS (device %s): couldn't "
+			       "remount because a RW-mount exists.\n",
+			       sb->s_id);
+			err = -EBUSY;
+			goto rw_remount_failed;
+		}
+		if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
+			printk(KERN_WARNING "NILFS (device %s): couldn't "
+			       "remount because the current RO-mount is not "
+			       "the latest one.\n",
+			       sb->s_id);
+			err = -EINVAL;
+			goto rw_remount_failed;
+		}
+		sb->s_flags &= ~MS_RDONLY;
+		nilfs_clear_opt(sbi, SNAPSHOT);
+		sbi->s_snapshot_cno = 0;
+
+		err = nilfs_attach_segment_constructor(sbi);
+		if (err)
+			goto rw_remount_failed;
+
+		down_write(&nilfs->ns_sem);
+		nilfs_setup_super(sbi);
+		up_write(&nilfs->ns_sem);
+
+		up(&sb->s_bdev->bd_mount_sem);
+	}
+ out:
+	return 0;
+
+ rw_remount_failed:
+	up(&sb->s_bdev->bd_mount_sem);
+ restore_opts:
+	sb->s_flags = old_sb_flags;
+	sbi->s_mount_opt = old_opts.mount_opt;
+	sbi->s_snapshot_cno = old_opts.snapshot_cno;
+	return err;
+}
+
+struct nilfs_super_data {
+	struct block_device *bdev;
+	__u64 cno;
+	int flags;
+};
+
+/**
+ * nilfs_identify - pre-read mount options needed to identify mount instance
+ * @data: mount options
+ * @sd: nilfs_super_data
+ */
+static int nilfs_identify(char *data, struct nilfs_super_data *sd)
+{
+	char *p, *options = data;
+	substring_t args[MAX_OPT_ARGS];
+	int option, token;
+	int ret = 0;
+
+	do {
+		p = strsep(&options, ",");
+		if (p != NULL && *p) {
+			token = match_token(p, tokens, args);
+			if (token == Opt_snapshot) {
+				if (!(sd->flags & MS_RDONLY))
+					ret++;
+				else {
+					ret = match_int(&args[0], &option);
+					if (!ret) {
+						if (option > 0)
+							sd->cno = option;
+						else
+							ret++;
+					}
+				}
+			}
+			if (ret)
+				printk(KERN_ERR
+				       "NILFS: invalid mount option: %s\n", p);
+		}
+		if (!options)
+			break;
+		BUG_ON(options == data);
+		*(options - 1) = ',';
+	} while (!ret);
+	return ret;
+}
+
+static int nilfs_set_bdev_super(struct super_block *s, void *data)
+{
+	struct nilfs_super_data *sd = data;
+
+	s->s_bdev = sd->bdev;
+	s->s_dev = s->s_bdev->bd_dev;
+	return 0;
+}
+
+static int nilfs_test_bdev_super(struct super_block *s, void *data)
+{
+	struct nilfs_super_data *sd = data;
+
+	return s->s_bdev == sd->bdev;
+}
+
+static int nilfs_test_bdev_super2(struct super_block *s, void *data)
+{
+	struct nilfs_super_data *sd = data;
+	int ret;
+
+	if (s->s_bdev != sd->bdev)
+		return 0;
+
+	if (!((s->s_flags | sd->flags) & MS_RDONLY))
+		return 1; /* Reuse an old R/W-mode super_block */
+
+	if (s->s_flags & sd->flags & MS_RDONLY) {
+		if (down_read_trylock(&s->s_umount)) {
+			ret = s->s_root &&
+				(sd->cno == NILFS_SB(s)->s_snapshot_cno);
+			up_read(&s->s_umount);
+			/*
+			 * This path is locked with sb_lock by sget().
+			 * So, drop_super() causes deadlock.
+			 */
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static int
+nilfs_get_sb(struct file_system_type *fs_type, int flags,
+	     const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	struct nilfs_super_data sd;
+	struct super_block *s, *s2;
+	struct the_nilfs *nilfs = NULL;
+	int err, need_to_close = 1;
+
+	sd.bdev = open_bdev_exclusive(dev_name, flags, fs_type);
+	if (IS_ERR(sd.bdev))
+		return PTR_ERR(sd.bdev);
+
+	/*
+	 * To get mount instance using sget() vfs-routine, NILFS needs
+	 * much more information than normal filesystems to identify mount
+	 * instance.  For snapshot mounts, not only a mount type (ro-mount
+	 * or rw-mount) but also a checkpoint number is required.
+	 * The results are passed in sget() using nilfs_super_data.
+	 */
+	sd.cno = 0;
+	sd.flags = flags;
+	if (nilfs_identify((char *)data, &sd)) {
+		err = -EINVAL;
+		goto failed;
+	}
+
+	/*
+	 * once the super is inserted into the list by sget, s_umount
+	 * will protect the lockfs code from trying to start a snapshot
+	 * while we are mounting
+	 */
+	down(&sd.bdev->bd_mount_sem);
+	if (!sd.cno &&
+	    (err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {
+		err = (err < 0) ? : -EBUSY;
+		goto failed_unlock;
+	}
+
+	/*
+	 * Phase-1: search any existent instance and get the_nilfs
+	 */
+	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);
+	if (IS_ERR(s))
+		goto error_s;
+
+	if (!s->s_root) {
+		err = -ENOMEM;
+		nilfs = alloc_nilfs(sd.bdev);
+		if (!nilfs)
+			goto cancel_new;
+	} else {
+		struct nilfs_sb_info *sbi = NILFS_SB(s);
+
+		/*
+		 * s_umount protects super_block from unmount process;
+		 * It covers pointers of nilfs_sb_info and the_nilfs.
+		 */
+		nilfs = sbi->s_nilfs;
+		get_nilfs(nilfs);
+		up_write(&s->s_umount);
+
+		/*
+		 * Phase-2: search specified snapshot or R/W mode super_block
+		 */
+		if (!sd.cno)
+			/* trying to get the latest checkpoint.  */
+			sd.cno = nilfs_last_cno(nilfs);
+
+		s2 = sget(fs_type, nilfs_test_bdev_super2,
+			  nilfs_set_bdev_super, &sd);
+		deactivate_super(s);
+		/*
+		 * Although deactivate_super() invokes close_bdev_exclusive() at
+		 * kill_block_super().  Here, s is an existent mount; we need
+		 * one more close_bdev_exclusive() call.
+		 */
+		s = s2;
+		if (IS_ERR(s))
+			goto error_s;
+	}
+
+	if (!s->s_root) {
+		char b[BDEVNAME_SIZE];
+
+		s->s_flags = flags;
+		strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
+		sb_set_blocksize(s, block_size(sd.bdev));
+
+		err = nilfs_fill_super(s, data, flags & MS_VERBOSE, nilfs);
+		if (err)
+			goto cancel_new;
+
+		s->s_flags |= MS_ACTIVE;
+		need_to_close = 0;
+	} else if (!(s->s_flags & MS_RDONLY)) {
+		err = -EBUSY;
+	}
+
+	up(&sd.bdev->bd_mount_sem);
+	put_nilfs(nilfs);
+	if (need_to_close)
+		close_bdev_exclusive(sd.bdev, flags);
+	simple_set_mnt(mnt, s);
+	return 0;
+
+ error_s:
+	up(&sd.bdev->bd_mount_sem);
+	if (nilfs)
+		put_nilfs(nilfs);
+	close_bdev_exclusive(sd.bdev, flags);
+	return PTR_ERR(s);
+
+ failed_unlock:
+	up(&sd.bdev->bd_mount_sem);
+ failed:
+	close_bdev_exclusive(sd.bdev, flags);
+
+	return err;
+
+ cancel_new:
+	/* Abandoning the newly allocated superblock */
+	up(&sd.bdev->bd_mount_sem);
+	if (nilfs)
+		put_nilfs(nilfs);
+	up_write(&s->s_umount);
+	deactivate_super(s);
+	/*
+	 * deactivate_super() invokes close_bdev_exclusive().
+	 * We must finish all post-cleaning before this call;
+	 * put_nilfs() and unlocking bd_mount_sem need the block device.
+	 */
+	return err;
+}
+
+static int nilfs_test_bdev_super3(struct super_block *s, void *data)
+{
+	struct nilfs_super_data *sd = data;
+	int ret;
+
+	if (s->s_bdev != sd->bdev)
+		return 0;
+	if (down_read_trylock(&s->s_umount)) {
+		ret = (s->s_flags & MS_RDONLY) && s->s_root &&
+			nilfs_test_opt(NILFS_SB(s), SNAPSHOT);
+		up_read(&s->s_umount);
+		if (ret)
+			return 0; /* ignore snapshot mounts */
+	}
+	return !((sd->flags ^ s->s_flags) & MS_RDONLY);
+}
+
+static int __false_bdev_super(struct super_block *s, void *data)
+{
+#if 0 /* XXX: workaround for lock debug. This is not good idea */
+	up_write(&s->s_umount);
+#endif
+	return -EFAULT;
+}
+
+/**
+ * test_exclusive_mount - check whether an exclusive RW/RO mount exists or not.
+ * fs_type: filesystem type
+ * bdev: block device
+ * flag: 0 (check rw-mount) or MS_RDONLY (check ro-mount)
+ * res: pointer to an integer to store result
+ *
+ * This function must be called within a section protected by bd_mount_mutex.
+ */
+static int test_exclusive_mount(struct file_system_type *fs_type,
+				struct block_device *bdev, int flags)
+{
+	struct super_block *s;
+	struct nilfs_super_data sd = { .flags = flags, .bdev = bdev };
+
+	s = sget(fs_type, nilfs_test_bdev_super3, __false_bdev_super, &sd);
+	if (IS_ERR(s)) {
+		if (PTR_ERR(s) != -EFAULT)
+			return PTR_ERR(s);
+		return 0;  /* Not found */
+	}
+	up_write(&s->s_umount);
+	deactivate_super(s);
+	return 1;  /* Found */
+}
+
+struct file_system_type nilfs_fs_type = {
+	.owner    = THIS_MODULE,
+	.name     = "nilfs2",
+	.get_sb   = nilfs_get_sb,
+	.kill_sb  = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+
+static int __init init_nilfs_fs(void)
+{
+	int err;
+
+	err = nilfs_init_inode_cache();
+	if (err)
+		goto failed;
+
+	err = nilfs_init_transaction_cache();
+	if (err)
+		goto failed_inode_cache;
+
+	err = nilfs_init_segbuf_cache();
+	if (err)
+		goto failed_transaction_cache;
+
+	err = nilfs_btree_path_cache_init();
+	if (err)
+		goto failed_segbuf_cache;
+
+	err = register_filesystem(&nilfs_fs_type);
+	if (err)
+		goto failed_btree_path_cache;
+
+	return 0;
+
+ failed_btree_path_cache:
+	nilfs_btree_path_cache_destroy();
+
+ failed_segbuf_cache:
+	nilfs_destroy_segbuf_cache();
+
+ failed_transaction_cache:
+	nilfs_destroy_transaction_cache();
+
+ failed_inode_cache:
+	nilfs_destroy_inode_cache();
+
+ failed:
+	return err;
+}
+
+static void __exit exit_nilfs_fs(void)
+{
+	nilfs_destroy_segbuf_cache();
+	nilfs_destroy_transaction_cache();
+	nilfs_destroy_inode_cache();
+	nilfs_btree_path_cache_destroy();
+	unregister_filesystem(&nilfs_fs_type);
+}
+
+module_init(init_nilfs_fs)
+module_exit(exit_nilfs_fs)
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
new file mode 100644
index 00000000000..33400cf0bbe
--- /dev/null
+++ b/fs/nilfs2/the_nilfs.c
@@ -0,0 +1,637 @@
+/*
+ * the_nilfs.c - the_nilfs shared structure.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/crc32.h>
+#include "nilfs.h"
+#include "segment.h"
+#include "alloc.h"
+#include "cpfile.h"
+#include "sufile.h"
+#include "dat.h"
+#include "seglist.h"
+#include "segbuf.h"
+
+void nilfs_set_last_segment(struct the_nilfs *nilfs,
+			    sector_t start_blocknr, u64 seq, __u64 cno)
+{
+	spin_lock(&nilfs->ns_last_segment_lock);
+	nilfs->ns_last_pseg = start_blocknr;
+	nilfs->ns_last_seq = seq;
+	nilfs->ns_last_cno = cno;
+	spin_unlock(&nilfs->ns_last_segment_lock);
+}
+
+/**
+ * alloc_nilfs - allocate the_nilfs structure
+ * @bdev: block device to which the_nilfs is related
+ *
+ * alloc_nilfs() allocates memory for the_nilfs and
+ * initializes its reference count and locks.
+ *
+ * Return Value: On success, pointer to the_nilfs is returned.
+ * On error, NULL is returned.
+ */
+struct the_nilfs *alloc_nilfs(struct block_device *bdev)
+{
+	struct the_nilfs *nilfs;
+
+	nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
+	if (!nilfs)
+		return NULL;
+
+	nilfs->ns_bdev = bdev;
+	atomic_set(&nilfs->ns_count, 1);
+	atomic_set(&nilfs->ns_writer_refcount, -1);
+	atomic_set(&nilfs->ns_ndirtyblks, 0);
+	init_rwsem(&nilfs->ns_sem);
+	mutex_init(&nilfs->ns_writer_mutex);
+	INIT_LIST_HEAD(&nilfs->ns_supers);
+	spin_lock_init(&nilfs->ns_last_segment_lock);
+	nilfs->ns_gc_inodes_h = NULL;
+	init_rwsem(&nilfs->ns_segctor_sem);
+
+	return nilfs;
+}
+
+/**
+ * put_nilfs - release a reference to the_nilfs
+ * @nilfs: the_nilfs structure to be released
+ *
+ * put_nilfs() decrements a reference counter of the_nilfs.
+ * If the reference count reaches zero, the_nilfs is freed.
+ */
+void put_nilfs(struct the_nilfs *nilfs)
+{
+	if (!atomic_dec_and_test(&nilfs->ns_count))
+		return;
+	/*
+	 * Increment of ns_count never occur below because the caller
+	 * of get_nilfs() holds at least one reference to the_nilfs.
+	 * Thus its exclusion control is not required here.
+	 */
+	might_sleep();
+	if (nilfs_loaded(nilfs)) {
+		nilfs_mdt_clear(nilfs->ns_sufile);
+		nilfs_mdt_destroy(nilfs->ns_sufile);
+		nilfs_mdt_clear(nilfs->ns_cpfile);
+		nilfs_mdt_destroy(nilfs->ns_cpfile);
+		nilfs_mdt_clear(nilfs->ns_dat);
+		nilfs_mdt_destroy(nilfs->ns_dat);
+		/* XXX: how and when to clear nilfs->ns_gc_dat? */
+		nilfs_mdt_destroy(nilfs->ns_gc_dat);
+	}
+	if (nilfs_init(nilfs)) {
+		nilfs_destroy_gccache(nilfs);
+		brelse(nilfs->ns_sbh[0]);
+		brelse(nilfs->ns_sbh[1]);
+	}
+	kfree(nilfs);
+}
+
+static int nilfs_load_super_root(struct the_nilfs *nilfs,
+				 struct nilfs_sb_info *sbi, sector_t sr_block)
+{
+	struct buffer_head *bh_sr;
+	struct nilfs_super_root *raw_sr;
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+	unsigned dat_entry_size, segment_usage_size, checkpoint_size;
+	unsigned inode_size;
+	int err;
+
+	err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
+	if (unlikely(err))
+		return err;
+
+	down_read(&nilfs->ns_sem);
+	dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
+	checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
+	segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
+	up_read(&nilfs->ns_sem);
+
+	inode_size = nilfs->ns_inode_size;
+
+	err = -ENOMEM;
+	nilfs->ns_dat = nilfs_mdt_new(
+		nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
+	if (unlikely(!nilfs->ns_dat))
+		goto failed;
+
+	nilfs->ns_gc_dat = nilfs_mdt_new(
+		nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
+	if (unlikely(!nilfs->ns_gc_dat))
+		goto failed_dat;
+
+	nilfs->ns_cpfile = nilfs_mdt_new(
+		nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
+	if (unlikely(!nilfs->ns_cpfile))
+		goto failed_gc_dat;
+
+	nilfs->ns_sufile = nilfs_mdt_new(
+		nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
+	if (unlikely(!nilfs->ns_sufile))
+		goto failed_cpfile;
+
+	err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
+	if (unlikely(err))
+		goto failed_sufile;
+
+	err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
+	if (unlikely(err))
+		goto failed_sufile;
+
+	nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
+	nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
+				 sizeof(struct nilfs_cpfile_header));
+	nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
+				 sizeof(struct nilfs_sufile_header));
+
+	err = nilfs_mdt_read_inode_direct(
+		nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
+	if (unlikely(err))
+		goto failed_sufile;
+
+	err = nilfs_mdt_read_inode_direct(
+		nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
+	if (unlikely(err))
+		goto failed_sufile;
+
+	err = nilfs_mdt_read_inode_direct(
+		nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
+	if (unlikely(err))
+		goto failed_sufile;
+
+	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
+	nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
+
+ failed:
+	brelse(bh_sr);
+	return err;
+
+ failed_sufile:
+	nilfs_mdt_destroy(nilfs->ns_sufile);
+
+ failed_cpfile:
+	nilfs_mdt_destroy(nilfs->ns_cpfile);
+
+ failed_gc_dat:
+	nilfs_mdt_destroy(nilfs->ns_gc_dat);
+
+ failed_dat:
+	nilfs_mdt_destroy(nilfs->ns_dat);
+	goto failed;
+}
+
+static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
+{
+	memset(ri, 0, sizeof(*ri));
+	INIT_LIST_HEAD(&ri->ri_used_segments);
+}
+
+static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
+{
+	nilfs_dispose_segment_list(&ri->ri_used_segments);
+}
+
+/**
+ * load_nilfs - load and recover the nilfs
+ * @nilfs: the_nilfs structure to be released
+ * @sbi: nilfs_sb_info used to recover past segment
+ *
+ * load_nilfs() searches and load the latest super root,
+ * attaches the last segment, and does recovery if needed.
+ * The caller must call this exclusively for simultaneous mounts.
+ */
+int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
+{
+	struct nilfs_recovery_info ri;
+	unsigned int s_flags = sbi->s_super->s_flags;
+	int really_read_only = bdev_read_only(nilfs->ns_bdev);
+	unsigned valid_fs;
+	int err = 0;
+
+	nilfs_init_recovery_info(&ri);
+
+	down_write(&nilfs->ns_sem);
+	valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
+	up_write(&nilfs->ns_sem);
+
+	if (!valid_fs && (s_flags & MS_RDONLY)) {
+		printk(KERN_INFO "NILFS: INFO: recovery "
+		       "required for readonly filesystem.\n");
+		if (really_read_only) {
+			printk(KERN_ERR "NILFS: write access "
+			       "unavailable, cannot proceed.\n");
+			err = -EROFS;
+			goto failed;
+		}
+		printk(KERN_INFO "NILFS: write access will "
+		       "be enabled during recovery.\n");
+		sbi->s_super->s_flags &= ~MS_RDONLY;
+	}
+
+	err = nilfs_search_super_root(nilfs, sbi, &ri);
+	if (unlikely(err)) {
+		printk(KERN_ERR "NILFS: error searching super root.\n");
+		goto failed;
+	}
+
+	err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
+	if (unlikely(err)) {
+		printk(KERN_ERR "NILFS: error loading super root.\n");
+		goto failed;
+	}
+
+	if (!valid_fs) {
+		err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
+		if (unlikely(err)) {
+			nilfs_mdt_destroy(nilfs->ns_cpfile);
+			nilfs_mdt_destroy(nilfs->ns_sufile);
+			nilfs_mdt_destroy(nilfs->ns_dat);
+			goto failed;
+		}
+		if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
+			sbi->s_super->s_dirt = 1;
+	}
+
+	set_nilfs_loaded(nilfs);
+
+ failed:
+	nilfs_clear_recovery_info(&ri);
+	sbi->s_super->s_flags = s_flags;
+	return err;
+}
+
+static unsigned long long nilfs_max_size(unsigned int blkbits)
+{
+	unsigned int max_bits;
+	unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
+
+	max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
+	if (max_bits < 64)
+		res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
+	return res;
+}
+
+static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
+				   struct nilfs_super_block *sbp)
+{
+	if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
+		printk(KERN_ERR "NILFS: revision mismatch "
+		       "(superblock rev.=%d.%d, current rev.=%d.%d). "
+		       "Please check the version of mkfs.nilfs.\n",
+		       le32_to_cpu(sbp->s_rev_level),
+		       le16_to_cpu(sbp->s_minor_rev_level),
+		       NILFS_CURRENT_REV, NILFS_MINOR_REV);
+		return -EINVAL;
+	}
+	nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
+	if (nilfs->ns_sbsize > BLOCK_SIZE)
+		return -EINVAL;
+
+	nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
+	nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
+
+	nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
+	if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
+		printk(KERN_ERR "NILFS: too short segment. \n");
+		return -EINVAL;
+	}
+
+	nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
+	nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
+	nilfs->ns_r_segments_percentage =
+		le32_to_cpu(sbp->s_r_segments_percentage);
+	nilfs->ns_nrsvsegs =
+		max_t(unsigned long, NILFS_MIN_NRSVSEGS,
+		      DIV_ROUND_UP(nilfs->ns_nsegments *
+				   nilfs->ns_r_segments_percentage, 100));
+	nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
+	return 0;
+}
+
+static int nilfs_valid_sb(struct nilfs_super_block *sbp)
+{
+	static unsigned char sum[4];
+	const int sumoff = offsetof(struct nilfs_super_block, s_sum);
+	size_t bytes;
+	u32 crc;
+
+	if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
+		return 0;
+	bytes = le16_to_cpu(sbp->s_bytes);
+	if (bytes > BLOCK_SIZE)
+		return 0;
+	crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
+		       sumoff);
+	crc = crc32_le(crc, sum, 4);
+	crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
+		       bytes - sumoff - 4);
+	return crc == le32_to_cpu(sbp->s_sum);
+}
+
+static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
+{
+	return offset < ((le64_to_cpu(sbp->s_nsegments) *
+			  le32_to_cpu(sbp->s_blocks_per_segment)) <<
+			 (le32_to_cpu(sbp->s_log_block_size) + 10));
+}
+
+static void nilfs_release_super_block(struct the_nilfs *nilfs)
+{
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		if (nilfs->ns_sbp[i]) {
+			brelse(nilfs->ns_sbh[i]);
+			nilfs->ns_sbh[i] = NULL;
+			nilfs->ns_sbp[i] = NULL;
+		}
+	}
+}
+
+void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
+{
+	brelse(nilfs->ns_sbh[0]);
+	nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
+	nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
+	nilfs->ns_sbh[1] = NULL;
+	nilfs->ns_sbp[1] = NULL;
+}
+
+void nilfs_swap_super_block(struct the_nilfs *nilfs)
+{
+	struct buffer_head *tsbh = nilfs->ns_sbh[0];
+	struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
+
+	nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
+	nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
+	nilfs->ns_sbh[1] = tsbh;
+	nilfs->ns_sbp[1] = tsbp;
+}
+
+static int nilfs_load_super_block(struct the_nilfs *nilfs,
+				  struct super_block *sb, int blocksize,
+				  struct nilfs_super_block **sbpp)
+{
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+	struct buffer_head **sbh = nilfs->ns_sbh;
+	u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
+	int valid[2], swp = 0;
+
+	sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
+					&sbh[0]);
+	sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
+
+	if (!sbp[0]) {
+		if (!sbp[1]) {
+			printk(KERN_ERR "NILFS: unable to read superblock\n");
+			return -EIO;
+		}
+		printk(KERN_WARNING
+		       "NILFS warning: unable to read primary superblock\n");
+	} else if (!sbp[1])
+		printk(KERN_WARNING
+		       "NILFS warning: unable to read secondary superblock\n");
+
+	valid[0] = nilfs_valid_sb(sbp[0]);
+	valid[1] = nilfs_valid_sb(sbp[1]);
+	swp = valid[1] &&
+		(!valid[0] ||
+		 le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
+
+	if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
+		brelse(sbh[1]);
+		sbh[1] = NULL;
+		sbp[1] = NULL;
+		swp = 0;
+	}
+	if (!valid[swp]) {
+		nilfs_release_super_block(nilfs);
+		printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
+		       sb->s_id);
+		return -EINVAL;
+	}
+
+	if (swp) {
+		printk(KERN_WARNING "NILFS warning: broken superblock. "
+		       "using spare superblock.\n");
+		nilfs_swap_super_block(nilfs);
+	}
+
+	nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
+	nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
+	nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
+	*sbpp = sbp[0];
+	return 0;
+}
+
+/**
+ * init_nilfs - initialize a NILFS instance.
+ * @nilfs: the_nilfs structure
+ * @sbi: nilfs_sb_info
+ * @sb: super block
+ * @data: mount options
+ *
+ * init_nilfs() performs common initialization per block device (e.g.
+ * reading the super block, getting disk layout information, initializing
+ * shared fields in the_nilfs). It takes on some portion of the jobs
+ * typically done by a fill_super() routine. This division arises from
+ * the nature that multiple NILFS instances may be simultaneously
+ * mounted on a device.
+ * For multiple mounts on the same device, only the first mount
+ * invokes these tasks.
+ *
+ * Return Value: On success, 0 is returned. On error, a negative error
+ * code is returned.
+ */
+int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
+{
+	struct super_block *sb = sbi->s_super;
+	struct nilfs_super_block *sbp;
+	struct backing_dev_info *bdi;
+	int blocksize;
+	int err;
+
+	down_write(&nilfs->ns_sem);
+	if (nilfs_init(nilfs)) {
+		/* Load values from existing the_nilfs */
+		sbp = nilfs->ns_sbp[0];
+		err = nilfs_store_magic_and_option(sb, sbp, data);
+		if (err)
+			goto out;
+
+		blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
+		if (sb->s_blocksize != blocksize &&
+		    !sb_set_blocksize(sb, blocksize)) {
+			printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
+			       blocksize);
+			err = -EINVAL;
+		}
+		sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
+		goto out;
+	}
+
+	blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
+	if (!blocksize) {
+		printk(KERN_ERR "NILFS: unable to set blocksize\n");
+		err = -EINVAL;
+		goto out;
+	}
+	err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
+	if (err)
+		goto out;
+
+	err = nilfs_store_magic_and_option(sb, sbp, data);
+	if (err)
+		goto failed_sbh;
+
+	blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
+	if (sb->s_blocksize != blocksize) {
+		int hw_blocksize = bdev_hardsect_size(sb->s_bdev);
+
+		if (blocksize < hw_blocksize) {
+			printk(KERN_ERR
+			       "NILFS: blocksize %d too small for device "
+			       "(sector-size = %d).\n",
+			       blocksize, hw_blocksize);
+			err = -EINVAL;
+			goto failed_sbh;
+		}
+		nilfs_release_super_block(nilfs);
+		sb_set_blocksize(sb, blocksize);
+
+		err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
+		if (err)
+			goto out;
+			/* not failed_sbh; sbh is released automatically
+			   when reloading fails. */
+	}
+	nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
+
+	err = nilfs_store_disk_layout(nilfs, sbp);
+	if (err)
+		goto failed_sbh;
+
+	sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
+
+	nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
+
+	bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
+	if (!bdi)
+		bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
+	nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
+
+	/* Finding last segment */
+	nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
+	nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
+	nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
+
+	nilfs->ns_seg_seq = nilfs->ns_last_seq;
+	nilfs->ns_segnum =
+		nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
+	nilfs->ns_cno = nilfs->ns_last_cno + 1;
+	if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
+		printk(KERN_ERR "NILFS invalid last segment number.\n");
+		err = -EINVAL;
+		goto failed_sbh;
+	}
+	/* Dummy values  */
+	nilfs->ns_free_segments_count =
+		nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
+
+	/* Initialize gcinode cache */
+	err = nilfs_init_gccache(nilfs);
+	if (err)
+		goto failed_sbh;
+
+	set_nilfs_init(nilfs);
+	err = 0;
+ out:
+	up_write(&nilfs->ns_sem);
+	return err;
+
+ failed_sbh:
+	nilfs_release_super_block(nilfs);
+	goto out;
+}
+
+int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
+{
+	struct inode *dat = nilfs_dat_inode(nilfs);
+	unsigned long ncleansegs;
+	int err;
+
+	down_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
+	up_read(&NILFS_MDT(dat)->mi_sem);	/* XXX */
+	if (likely(!err))
+		*nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
+	return err;
+}
+
+int nilfs_near_disk_full(struct the_nilfs *nilfs)
+{
+	struct inode *sufile = nilfs->ns_sufile;
+	unsigned long ncleansegs, nincsegs;
+	int ret;
+
+	ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
+	if (likely(!ret)) {
+		nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
+			nilfs->ns_blocks_per_segment + 1;
+		if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
+			ret++;
+	}
+	return ret;
+}
+
+int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
+				int snapshot_mount)
+{
+	struct nilfs_sb_info *sbi;
+	int ret = 0;
+
+	down_read(&nilfs->ns_sem);
+	if (cno == 0 || cno > nilfs->ns_cno)
+		goto out_unlock;
+
+	list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
+		if (sbi->s_snapshot_cno == cno &&
+		    (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
+					/* exclude read-only mounts */
+			ret++;
+			break;
+		}
+	}
+	/* for protecting recent checkpoints */
+	if (cno >= nilfs_last_cno(nilfs))
+		ret++;
+
+ out_unlock:
+	up_read(&nilfs->ns_sem);
+	return ret;
+}
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
new file mode 100644
index 00000000000..30fe58778d0
--- /dev/null
+++ b/fs/nilfs2/the_nilfs.h
@@ -0,0 +1,298 @@
+/*
+ * the_nilfs.h - the_nilfs shared structure.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#ifndef _THE_NILFS_H
+#define _THE_NILFS_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include "sb.h"
+
+/* the_nilfs struct */
+enum {
+	THE_NILFS_INIT = 0,     /* Information from super_block is set */
+	THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
+				   the latest checkpoint was loaded */
+	THE_NILFS_DISCONTINUED,	/* 'next' pointer chain has broken */
+};
+
+/**
+ * struct the_nilfs - struct to supervise multiple nilfs mount points
+ * @ns_flags: flags
+ * @ns_count: reference count
+ * @ns_bdev: block device
+ * @ns_bdi: backing dev info
+ * @ns_writer: back pointer to writable nilfs_sb_info
+ * @ns_sem: semaphore for shared states
+ * @ns_writer_mutex: mutex protecting ns_writer attach/detach
+ * @ns_writer_refcount: number of referrers on ns_writer
+ * @ns_sbh: buffer heads of on-disk super blocks
+ * @ns_sbp: pointers to super block data
+ * @ns_sbwtime: previous write time of super blocks
+ * @ns_sbsize: size of valid data in super block
+ * @ns_supers: list of nilfs super block structs
+ * @ns_seg_seq: segment sequence counter
+ * @ns_segnum: index number of the latest full segment.
+ * @ns_nextnum: index number of the full segment index to be used next
+ * @ns_pseg_offset: offset of next partial segment in the current full segment
+ * @ns_cno: next checkpoint number
+ * @ns_ctime: write time of the last segment
+ * @ns_nongc_ctime: write time of the last segment not for cleaner operation
+ * @ns_ndirtyblks: Number of dirty data blocks
+ * @ns_last_segment_lock: lock protecting fields for the latest segment
+ * @ns_last_pseg: start block number of the latest segment
+ * @ns_last_seq: sequence value of the latest segment
+ * @ns_last_cno: checkpoint number of the latest segment
+ * @ns_prot_seq: least sequence number of segments which must not be reclaimed
+ * @ns_free_segments_count: counter of free segments
+ * @ns_segctor_sem: segment constructor semaphore
+ * @ns_dat: DAT file inode
+ * @ns_cpfile: checkpoint file inode
+ * @ns_sufile: segusage file inode
+ * @ns_gc_dat: shadow inode of the DAT file inode for GC
+ * @ns_gc_inodes: dummy inodes to keep live blocks
+ * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
+ * @ns_blocksize_bits: bit length of block size
+ * @ns_nsegments: number of segments in filesystem
+ * @ns_blocks_per_segment: number of blocks per segment
+ * @ns_r_segments_percentage: reserved segments percentage
+ * @ns_nrsvsegs: number of reserved segments
+ * @ns_first_data_block: block number of first data block
+ * @ns_inode_size: size of on-disk inode
+ * @ns_first_ino: first not-special inode number
+ * @ns_crc_seed: seed value of CRC32 calculation
+ */
+struct the_nilfs {
+	unsigned long		ns_flags;
+	atomic_t		ns_count;
+
+	struct block_device    *ns_bdev;
+	struct backing_dev_info *ns_bdi;
+	struct nilfs_sb_info   *ns_writer;
+	struct rw_semaphore	ns_sem;
+	struct mutex		ns_writer_mutex;
+	atomic_t		ns_writer_refcount;
+
+	/*
+	 * used for
+	 * - loading the latest checkpoint exclusively.
+	 * - allocating a new full segment.
+	 * - protecting s_dirt in the super_block struct
+	 *   (see nilfs_write_super) and the following fields.
+	 */
+	struct buffer_head     *ns_sbh[2];
+	struct nilfs_super_block *ns_sbp[2];
+	time_t			ns_sbwtime[2];
+	unsigned		ns_sbsize;
+	unsigned		ns_mount_state;
+	struct list_head	ns_supers;
+
+	/*
+	 * Following fields are dedicated to a writable FS-instance.
+	 * Except for the period seeking checkpoint, code outside the segment
+	 * constructor must lock a segment semaphore while accessing these
+	 * fields.
+	 * The writable FS-instance is sole during a lifetime of the_nilfs.
+	 */
+	u64			ns_seg_seq;
+	__u64			ns_segnum;
+	__u64			ns_nextnum;
+	unsigned long		ns_pseg_offset;
+	__u64			ns_cno;
+	time_t			ns_ctime;
+	time_t			ns_nongc_ctime;
+	atomic_t		ns_ndirtyblks;
+
+	/*
+	 * The following fields hold information on the latest partial segment
+	 * written to disk with a super root.  These fields are protected by
+	 * ns_last_segment_lock.
+	 */
+	spinlock_t		ns_last_segment_lock;
+	sector_t		ns_last_pseg;
+	u64			ns_last_seq;
+	__u64			ns_last_cno;
+	u64			ns_prot_seq;
+	unsigned long		ns_free_segments_count;
+
+	struct rw_semaphore	ns_segctor_sem;
+
+	/*
+	 * Following fields are lock free except for the period before
+	 * the_nilfs is initialized.
+	 */
+	struct inode	       *ns_dat;
+	struct inode	       *ns_cpfile;
+	struct inode	       *ns_sufile;
+	struct inode	       *ns_gc_dat;
+
+	/* GC inode list and hash table head */
+	struct list_head	ns_gc_inodes;
+	struct hlist_head      *ns_gc_inodes_h;
+
+	/* Disk layout information (static) */
+	unsigned int		ns_blocksize_bits;
+	unsigned long		ns_nsegments;
+	unsigned long		ns_blocks_per_segment;
+	unsigned long		ns_r_segments_percentage;
+	unsigned long		ns_nrsvsegs;
+	unsigned long		ns_first_data_block;
+	int			ns_inode_size;
+	int			ns_first_ino;
+	u32			ns_crc_seed;
+};
+
+#define NILFS_GCINODE_HASH_BITS		8
+#define NILFS_GCINODE_HASH_SIZE		(1<<NILFS_GCINODE_HASH_BITS)
+
+#define THE_NILFS_FNS(bit, name)					\
+static inline void set_nilfs_##name(struct the_nilfs *nilfs)		\
+{									\
+	set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
+}									\
+static inline void clear_nilfs_##name(struct the_nilfs *nilfs)		\
+{									\
+	clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
+}									\
+static inline int nilfs_##name(struct the_nilfs *nilfs)			\
+{									\
+	return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);		\
+}
+
+THE_NILFS_FNS(INIT, init)
+THE_NILFS_FNS(LOADED, loaded)
+THE_NILFS_FNS(DISCONTINUED, discontinued)
+
+/* Minimum interval of periodical update of superblocks (in seconds) */
+#define NILFS_SB_FREQ		10
+#define NILFS_ALTSB_FREQ	60  /* spare superblock */
+
+void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
+struct the_nilfs *alloc_nilfs(struct block_device *);
+void put_nilfs(struct the_nilfs *);
+int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
+int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
+int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
+int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
+int nilfs_near_disk_full(struct the_nilfs *);
+void nilfs_fall_back_super_block(struct the_nilfs *);
+void nilfs_swap_super_block(struct the_nilfs *);
+
+
+static inline void get_nilfs(struct the_nilfs *nilfs)
+{
+	/* Caller must have at least one reference of the_nilfs. */
+	atomic_inc(&nilfs->ns_count);
+}
+
+static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
+{
+	if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
+		mutex_lock(&nilfs->ns_writer_mutex);
+	return nilfs->ns_writer;
+}
+
+static inline void nilfs_put_writer(struct the_nilfs *nilfs)
+{
+	if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
+		mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
+{
+	mutex_lock(&nilfs->ns_writer_mutex);
+	nilfs->ns_writer = sbi;
+	mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
+{
+	mutex_lock(&nilfs->ns_writer_mutex);
+	if (sbi == nilfs->ns_writer)
+		nilfs->ns_writer = NULL;
+	mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
+			sector_t *seg_start, sector_t *seg_end)
+{
+	*seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
+	*seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
+	if (segnum == 0)
+		*seg_start = nilfs->ns_first_data_block;
+}
+
+static inline sector_t
+nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
+{
+	return (segnum == 0) ? nilfs->ns_first_data_block :
+		(sector_t)nilfs->ns_blocks_per_segment * segnum;
+}
+
+static inline __u64
+nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
+{
+	sector_t segnum = blocknr;
+
+	sector_div(segnum, nilfs->ns_blocks_per_segment);
+	return segnum;
+}
+
+static inline void
+nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
+			sector_t seg_end)
+{
+	/* terminate the current full segment (used in case of I/O-error) */
+	nilfs->ns_pseg_offset = seg_end - seg_start + 1;
+}
+
+static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
+{
+	/* move forward with a full segment */
+	nilfs->ns_segnum = nilfs->ns_nextnum;
+	nilfs->ns_pseg_offset = 0;
+	nilfs->ns_seg_seq++;
+}
+
+static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
+{
+	__u64 cno;
+
+	spin_lock(&nilfs->ns_last_segment_lock);
+	cno = nilfs->ns_last_cno;
+	spin_unlock(&nilfs->ns_last_segment_lock);
+	return cno;
+}
+
+static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
+{
+	return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
+}
+
+#endif /* _THE_NILFS_H */