/* * linux/fs/ext3/balloc.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) * * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 * Big-endian to little-endian byte-swapping/bitmaps by * David S. Miller (davem@caip.rutgers.edu), 1995 */ #include <linux/config.h> #include <linux/time.h> #include <linux/capability.h> #include <linux/fs.h> #include <linux/jbd.h> #include <linux/ext3_fs.h> #include <linux/ext3_jbd.h> #include <linux/quotaops.h> #include <linux/buffer_head.h> /* * balloc.c contains the blocks allocation and deallocation routines */ /* * The free blocks are managed by bitmaps. A file system contains several * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap * block for inodes, N blocks for the inode table and data blocks. * * The file system contains group descriptors which are located after the * super block. Each descriptor contains the number of the bitmap block and * the free blocks count in the block. The descriptors are loaded in memory * when a file system is mounted (see ext3_read_super). */ #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb, unsigned int block_group, struct buffer_head ** bh) { unsigned long group_desc; unsigned long offset; struct ext3_group_desc * desc; struct ext3_sb_info *sbi = EXT3_SB(sb); if (block_group >= sbi->s_groups_count) { ext3_error (sb, "ext3_get_group_desc", "block_group >= groups_count - " "block_group = %d, groups_count = %lu", block_group, sbi->s_groups_count); return NULL; } smp_rmb(); group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb); offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1); if (!sbi->s_group_desc[group_desc]) { ext3_error (sb, "ext3_get_group_desc", "Group descriptor not loaded - " "block_group = %d, group_desc = %lu, desc = %lu", block_group, group_desc, offset); return NULL; } desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data; if (bh) *bh = sbi->s_group_desc[group_desc]; return desc + offset; } /* * Read the bitmap for a given block_group, reading into the specified * slot in the superblock's bitmap cache. * * Return buffer_head on success or NULL in case of failure. */ static struct buffer_head * read_block_bitmap(struct super_block *sb, unsigned int block_group) { struct ext3_group_desc * desc; struct buffer_head * bh = NULL; desc = ext3_get_group_desc (sb, block_group, NULL); if (!desc) goto error_out; bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap)); if (!bh) ext3_error (sb, "read_block_bitmap", "Cannot read block bitmap - " "block_group = %d, block_bitmap = %u", block_group, le32_to_cpu(desc->bg_block_bitmap)); error_out: return bh; } /* * The reservation window structure operations * -------------------------------------------- * Operations include: * dump, find, add, remove, is_empty, find_next_reservable_window, etc. * * We use sorted double linked list for the per-filesystem reservation * window list. (like in vm_region). * * Initially, we keep those small operations in the abstract functions, * so later if we need a better searching tree than double linked-list, * we could easily switch to that without changing too much * code. */ #if 0 static void __rsv_window_dump(struct rb_root *root, int verbose, const char *fn) { struct rb_node *n; struct ext3_reserve_window_node *rsv, *prev; int bad; restart: n = rb_first(root); bad = 0; prev = NULL; printk("Block Allocation Reservation Windows Map (%s):\n", fn); while (n) { rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node); if (verbose) printk("reservation window 0x%p " "start: %d, end: %d\n", rsv, rsv->rsv_start, rsv->rsv_end); if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) { printk("Bad reservation %p (start >= end)\n", rsv); bad = 1; } if (prev && prev->rsv_end >= rsv->rsv_start) { printk("Bad reservation %p (prev->end >= start)\n", rsv); bad = 1; } if (bad) { if (!verbose) { printk("Restarting reservation walk in verbose mode\n"); verbose = 1; goto restart; } } n = rb_next(n); prev = rsv; } printk("Window map complete.\n"); if (bad) BUG(); } #define rsv_window_dump(root, verbose) \ __rsv_window_dump((root), (verbose), __FUNCTION__) #else #define rsv_window_dump(root, verbose) do {} while (0) #endif static int goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal, unsigned int group, struct super_block * sb) { unsigned long group_first_block, group_last_block; group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) + group * EXT3_BLOCKS_PER_GROUP(sb); group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1; if ((rsv->_rsv_start > group_last_block) || (rsv->_rsv_end < group_first_block)) return 0; if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start) || (goal + group_first_block > rsv->_rsv_end))) return 0; return 1; } /* * Find the reserved window which includes the goal, or the previous one * if the goal is not in any window. * Returns NULL if there are no windows or if all windows start after the goal. */ static struct ext3_reserve_window_node * search_reserve_window(struct rb_root *root, unsigned long goal) { struct rb_node *n = root->rb_node; struct ext3_reserve_window_node *rsv; if (!n) return NULL; do { rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node); if (goal < rsv->rsv_start) n = n->rb_left; else if (goal > rsv->rsv_end) n = n->rb_right; else return rsv; } while (n); /* * We've fallen off the end of the tree: the goal wasn't inside * any particular node. OK, the previous node must be to one * side of the interval containing the goal. If it's the RHS, * we need to back up one. */ if (rsv->rsv_start > goal) { n = rb_prev(&rsv->rsv_node); rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node); } return rsv; } void ext3_rsv_window_add(struct super_block *sb, struct ext3_reserve_window_node *rsv) { struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root; struct rb_node *node = &rsv->rsv_node; unsigned int start = rsv->rsv_start; struct rb_node ** p = &root->rb_node; struct rb_node * parent = NULL; struct ext3_reserve_window_node *this; while (*p) { parent = *p; this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node); if (start < this->rsv_start) p = &(*p)->rb_left; else if (start > this->rsv_end) p = &(*p)->rb_right; else BUG(); } rb_link_node(node, parent, p); rb_insert_color(node, root); } static void rsv_window_remove(struct super_block *sb, struct ext3_reserve_window_node *rsv) { rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; rsv->rsv_alloc_hit = 0; rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root); } static inline int rsv_is_empty(struct ext3_reserve_window *rsv) { /* a valid reservation end block could not be 0 */ return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED); } void ext3_init_block_alloc_info(struct inode *inode) { struct ext3_inode_info *ei = EXT3_I(inode); struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info; struct super_block *sb = inode->i_sb; block_i = kmalloc(sizeof(*block_i), GFP_NOFS); if (block_i) { struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node; rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; /* * if filesystem is mounted with NORESERVATION, the goal * reservation window size is set to zero to indicate * block reservation is off */ if (!test_opt(sb, RESERVATION)) rsv->rsv_goal_size = 0; else rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS; rsv->rsv_alloc_hit = 0; block_i->last_alloc_logical_block = 0; block_i->last_alloc_physical_block = 0; } ei->i_block_alloc_info = block_i; } void ext3_discard_reservation(struct inode *inode) { struct ext3_inode_info *ei = EXT3_I(inode); struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info; struct ext3_reserve_window_node *rsv; spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock; if (!block_i) return; rsv = &block_i->rsv_window_node; if (!rsv_is_empty(&rsv->rsv_window)) { spin_lock(rsv_lock); if (!rsv_is_empty(&rsv->rsv_window)) rsv_window_remove(inode->i_sb, rsv); spin_unlock(rsv_lock); } } /* Free given blocks, update quota and i_blocks field */ void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb, unsigned long block, unsigned long count, int *pdquot_freed_blocks) { struct buffer_head *bitmap_bh = NULL; struct buffer_head *gd_bh; unsigned long block_group; unsigned long bit; unsigned long i; unsigned long overflow; struct ext3_group_desc * desc; struct ext3_super_block * es; struct ext3_sb_info *sbi; int err = 0, ret; unsigned group_freed; *pdquot_freed_blocks = 0; sbi = EXT3_SB(sb); es = sbi->s_es; if (block < le32_to_cpu(es->s_first_data_block) || block + count < block || block + count > le32_to_cpu(es->s_blocks_count)) { ext3_error (sb, "ext3_free_blocks", "Freeing blocks not in datazone - " "block = %lu, count = %lu", block, count); goto error_return; } ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1); do_more: overflow = 0; block_group = (block - le32_to_cpu(es->s_first_data_block)) / EXT3_BLOCKS_PER_GROUP(sb); bit = (block - le32_to_cpu(es->s_first_data_block)) % EXT3_BLOCKS_PER_GROUP(sb); /* * Check to see if we are freeing blocks across a group * boundary. */ if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) { overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb); count -= overflow; } brelse(bitmap_bh); bitmap_bh = read_block_bitmap(sb, block_group); if (!bitmap_bh) goto error_return; desc = ext3_get_group_desc (sb, block_group, &gd_bh); if (!desc) goto error_return; if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) || in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) || in_range (block, le32_to_cpu(desc->bg_inode_table), sbi->s_itb_per_group) || in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table), sbi->s_itb_per_group)) ext3_error (sb, "ext3_free_blocks", "Freeing blocks in system zones - " "Block = %lu, count = %lu", block, count); /* * We are about to start releasing blocks in the bitmap, * so we need undo access. */ /* @@@ check errors */ BUFFER_TRACE(bitmap_bh, "getting undo access"); err = ext3_journal_get_undo_access(handle, bitmap_bh); if (err) goto error_return; /* * We are about to modify some metadata. Call the journal APIs * to unshare ->b_data if a currently-committing transaction is * using it */ BUFFER_TRACE(gd_bh, "get_write_access"); err = ext3_journal_get_write_access(handle, gd_bh); if (err) goto error_return; jbd_lock_bh_state(bitmap_bh); for (i = 0, group_freed = 0; i < count; i++) { /* * An HJ special. This is expensive... */ #ifdef CONFIG_JBD_DEBUG jbd_unlock_bh_state(bitmap_bh); { struct buffer_head *debug_bh; debug_bh = sb_find_get_block(sb, block + i); if (debug_bh) { BUFFER_TRACE(debug_bh, "Deleted!"); if (!bh2jh(bitmap_bh)->b_committed_data) BUFFER_TRACE(debug_bh, "No commited data in bitmap"); BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap"); __brelse(debug_bh); } } jbd_lock_bh_state(bitmap_bh); #endif if (need_resched()) { jbd_unlock_bh_state(bitmap_bh); cond_resched(); jbd_lock_bh_state(bitmap_bh); } /* @@@ This prevents newly-allocated data from being * freed and then reallocated within the same * transaction. * * Ideally we would want to allow that to happen, but to * do so requires making journal_forget() capable of * revoking the queued write of a data block, which * implies blocking on the journal lock. *forget() * cannot block due to truncate races. * * Eventually we can fix this by making journal_forget() * return a status indicating whether or not it was able * to revoke the buffer. On successful revoke, it is * safe not to set the allocation bit in the committed * bitmap, because we know that there is no outstanding * activity on the buffer any more and so it is safe to * reallocate it. */ BUFFER_TRACE(bitmap_bh, "set in b_committed_data"); J_ASSERT_BH(bitmap_bh, bh2jh(bitmap_bh)->b_committed_data != NULL); ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i, bh2jh(bitmap_bh)->b_committed_data); /* * We clear the bit in the bitmap after setting the committed * data bit, because this is the reverse order to that which * the allocator uses. */ BUFFER_TRACE(bitmap_bh, "clear bit"); if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i, bitmap_bh->b_data)) { jbd_unlock_bh_state(bitmap_bh); ext3_error(sb, __FUNCTION__, "bit already cleared for block %lu", block + i); jbd_lock_bh_state(bitmap_bh); BUFFER_TRACE(bitmap_bh, "bit already cleared"); } else { group_freed++; } } jbd_unlock_bh_state(bitmap_bh); spin_lock(sb_bgl_lock(sbi, block_group)); desc->bg_free_blocks_count = cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) + group_freed); spin_unlock(sb_bgl_lock(sbi, block_group)); percpu_counter_mod(&sbi->s_freeblocks_counter, count); /* We dirtied the bitmap block */ BUFFER_TRACE(bitmap_bh, "dirtied bitmap block"); err = ext3_journal_dirty_metadata(handle, bitmap_bh); /* And the group descriptor block */ BUFFER_TRACE(gd_bh, "dirtied group descriptor block"); ret = ext3_journal_dirty_metadata(handle, gd_bh); if (!err) err = ret; *pdquot_freed_blocks += group_freed; if (overflow && !err) { block += count; count = overflow; goto do_more; } sb->s_dirt = 1; error_return: brelse(bitmap_bh); ext3_std_error(sb, err); return; } /* Free given blocks, update quota and i_blocks field */ void ext3_free_blocks(handle_t *handle, struct inode *inode, unsigned long block, unsigned long count) { struct super_block * sb; int dquot_freed_blocks; sb = inode->i_sb; if (!sb) { printk ("ext3_free_blocks: nonexistent device"); return; } ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks); if (dquot_freed_blocks) DQUOT_FREE_BLOCK(inode, dquot_freed_blocks); return; } /* * For ext3 allocations, we must not reuse any blocks which are * allocated in the bitmap buffer's "last committed data" copy. This * prevents deletes from freeing up the page for reuse until we have * committed the delete transaction. * * If we didn't do this, then deleting something and reallocating it as * data would allow the old block to be overwritten before the * transaction committed (because we force data to disk before commit). * This would lead to corruption if we crashed between overwriting the * data and committing the delete. * * @@@ We may want to make this allocation behaviour conditional on * data-writes at some point, and disable it for metadata allocations or * sync-data inodes. */ static int ext3_test_allocatable(int nr, struct buffer_head *bh) { int ret; struct journal_head *jh = bh2jh(bh); if (ext3_test_bit(nr, bh->b_data)) return 0; jbd_lock_bh_state(bh); if (!jh->b_committed_data) ret = 1; else ret = !ext3_test_bit(nr, jh->b_committed_data); jbd_unlock_bh_state(bh); return ret; } static int bitmap_search_next_usable_block(int start, struct buffer_head *bh, int maxblocks) { int next; struct journal_head *jh = bh2jh(bh); /* * The bitmap search --- search forward alternately through the actual * bitmap and the last-committed copy until we find a bit free in * both */ while (start < maxblocks) { next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start); if (next >= maxblocks) return -1; if (ext3_test_allocatable(next, bh)) return next; jbd_lock_bh_state(bh); if (jh->b_committed_data) start = ext3_find_next_zero_bit(jh->b_committed_data, maxblocks, next); jbd_unlock_bh_state(bh); } return -1; } /* * Find an allocatable block in a bitmap. We honour both the bitmap and * its last-committed copy (if that exists), and perform the "most * appropriate allocation" algorithm of looking for a free block near * the initial goal; then for a free byte somewhere in the bitmap; then * for any free bit in the bitmap. */ static int find_next_usable_block(int start, struct buffer_head *bh, int maxblocks) { int here, next; char *p, *r; if (start > 0) { /* * The goal was occupied; search forward for a free * block within the next XX blocks. * * end_goal is more or less random, but it has to be * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the * next 64-bit boundary is simple.. */ int end_goal = (start + 63) & ~63; if (end_goal > maxblocks) end_goal = maxblocks; here = ext3_find_next_zero_bit(bh->b_data, end_goal, start); if (here < end_goal && ext3_test_allocatable(here, bh)) return here; ext3_debug("Bit not found near goal\n"); } here = start; if (here < 0) here = 0; p = ((char *)bh->b_data) + (here >> 3); r = memscan(p, 0, (maxblocks - here + 7) >> 3); next = (r - ((char *)bh->b_data)) << 3; if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh)) return next; /* * The bitmap search --- search forward alternately through the actual * bitmap and the last-committed copy until we find a bit free in * both */ here = bitmap_search_next_usable_block(here, bh, maxblocks); return here; } /* * We think we can allocate this block in this bitmap. Try to set the bit. * If that succeeds then check that nobody has allocated and then freed the * block since we saw that is was not marked in b_committed_data. If it _was_ * allocated and freed then clear the bit in the bitmap again and return * zero (failure). */ static inline int claim_block(spinlock_t *lock, int block, struct buffer_head *bh) { struct journal_head *jh = bh2jh(bh); int ret; if (ext3_set_bit_atomic(lock, block, bh->b_data)) return 0; jbd_lock_bh_state(bh); if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) { ext3_clear_bit_atomic(lock, block, bh->b_data); ret = 0; } else { ret = 1; } jbd_unlock_bh_state(bh); return ret; } /* * If we failed to allocate the desired block then we may end up crossing to a * new bitmap. In that case we must release write access to the old one via * ext3_journal_release_buffer(), else we'll run out of credits. */ static int ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group, struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv) { int group_first_block, start, end; /* we do allocation within the reservation window if we have a window */ if (my_rsv) { group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) + group * EXT3_BLOCKS_PER_GROUP(sb); if (my_rsv->_rsv_start >= group_first_block) start = my_rsv->_rsv_start - group_first_block; else /* reservation window cross group boundary */ start = 0; end = my_rsv->_rsv_end - group_first_block + 1; if (end > EXT3_BLOCKS_PER_GROUP(sb)) /* reservation window crosses group boundary */ end = EXT3_BLOCKS_PER_GROUP(sb); if ((start <= goal) && (goal < end)) start = goal; else goal = -1; } else { if (goal > 0) start = goal; else start = 0; end = EXT3_BLOCKS_PER_GROUP(sb); } BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb)); repeat: if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) { goal = find_next_usable_block(start, bitmap_bh, end); if (goal < 0) goto fail_access; if (!my_rsv) { int i; for (i = 0; i < 7 && goal > start && ext3_test_allocatable(goal - 1, bitmap_bh); i++, goal--) ; } } start = goal; if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) { /* * The block was allocated by another thread, or it was * allocated and then freed by another thread */ start++; goal++; if (start >= end) goto fail_access; goto repeat; } return goal; fail_access: return -1; } /** * find_next_reservable_window(): * find a reservable space within the given range. * It does not allocate the reservation window for now: * alloc_new_reservation() will do the work later. * * @search_head: the head of the searching list; * This is not necessarily the list head of the whole filesystem * * We have both head and start_block to assist the search * for the reservable space. The list starts from head, * but we will shift to the place where start_block is, * then start from there, when looking for a reservable space. * * @size: the target new reservation window size * * @group_first_block: the first block we consider to start * the real search from * * @last_block: * the maximum block number that our goal reservable space * could start from. This is normally the last block in this * group. The search will end when we found the start of next * possible reservable space is out of this boundary. * This could handle the cross boundary reservation window * request. * * basically we search from the given range, rather than the whole * reservation double linked list, (start_block, last_block) * to find a free region that is of my size and has not * been reserved. * */ static int find_next_reservable_window( struct ext3_reserve_window_node *search_head, struct ext3_reserve_window_node *my_rsv, struct super_block * sb, int start_block, int last_block) { struct rb_node *next; struct ext3_reserve_window_node *rsv, *prev; int cur; int size = my_rsv->rsv_goal_size; /* TODO: make the start of the reservation window byte-aligned */ /* cur = *start_block & ~7;*/ cur = start_block; rsv = search_head; if (!rsv) return -1; while (1) { if (cur <= rsv->rsv_end) cur = rsv->rsv_end + 1; /* TODO? * in the case we could not find a reservable space * that is what is expected, during the re-search, we could * remember what's the largest reservable space we could have * and return that one. * * For now it will fail if we could not find the reservable * space with expected-size (or more)... */ if (cur > last_block) return -1; /* fail */ prev = rsv; next = rb_next(&rsv->rsv_node); rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node); /* * Reached the last reservation, we can just append to the * previous one. */ if (!next) break; if (cur + size <= rsv->rsv_start) { /* * Found a reserveable space big enough. We could * have a reservation across the group boundary here */ break; } } /* * we come here either : * when we reach the end of the whole list, * and there is empty reservable space after last entry in the list. * append it to the end of the list. * * or we found one reservable space in the middle of the list, * return the reservation window that we could append to. * succeed. */ if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window))) rsv_window_remove(sb, my_rsv); /* * Let's book the whole avaliable window for now. We will check the * disk bitmap later and then, if there are free blocks then we adjust * the window size if it's larger than requested. * Otherwise, we will remove this node from the tree next time * call find_next_reservable_window. */ my_rsv->rsv_start = cur; my_rsv->rsv_end = cur + size - 1; my_rsv->rsv_alloc_hit = 0; if (prev != my_rsv) ext3_rsv_window_add(sb, my_rsv); return 0; } /** * alloc_new_reservation()--allocate a new reservation window * * To make a new reservation, we search part of the filesystem * reservation list (the list that inside the group). We try to * allocate a new reservation window near the allocation goal, * or the beginning of the group, if there is no goal. * * We first find a reservable space after the goal, then from * there, we check the bitmap for the first free block after * it. If there is no free block until the end of group, then the * whole group is full, we failed. Otherwise, check if the free * block is inside the expected reservable space, if so, we * succeed. * If the first free block is outside the reservable space, then * start from the first free block, we search for next available * space, and go on. * * on succeed, a new reservation will be found and inserted into the list * It contains at least one free block, and it does not overlap with other * reservation windows. * * failed: we failed to find a reservation window in this group * * @rsv: the reservation * * @goal: The goal (group-relative). It is where the search for a * free reservable space should start from. * if we have a goal(goal >0 ), then start from there, * no goal(goal = -1), we start from the first block * of the group. * * @sb: the super block * @group: the group we are trying to allocate in * @bitmap_bh: the block group block bitmap * */ static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv, int goal, struct super_block *sb, unsigned int group, struct buffer_head *bitmap_bh) { struct ext3_reserve_window_node *search_head; int group_first_block, group_end_block, start_block; int first_free_block; struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root; unsigned long size; int ret; spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock; group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) + group * EXT3_BLOCKS_PER_GROUP(sb); group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1; if (goal < 0) start_block = group_first_block; else start_block = goal + group_first_block; size = my_rsv->rsv_goal_size; if (!rsv_is_empty(&my_rsv->rsv_window)) { /* * if the old reservation is cross group boundary * and if the goal is inside the old reservation window, * we will come here when we just failed to allocate from * the first part of the window. We still have another part * that belongs to the next group. In this case, there is no * point to discard our window and try to allocate a new one * in this group(which will fail). we should * keep the reservation window, just simply move on. * * Maybe we could shift the start block of the reservation * window to the first block of next group. */ if ((my_rsv->rsv_start <= group_end_block) && (my_rsv->rsv_end > group_end_block) && (start_block >= my_rsv->rsv_start)) return -1; if ((my_rsv->rsv_alloc_hit > (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) { /* * if we previously allocation hit ration is greater than half * we double the size of reservation window next time * otherwise keep the same */ size = size * 2; if (size > EXT3_MAX_RESERVE_BLOCKS) size = EXT3_MAX_RESERVE_BLOCKS; my_rsv->rsv_goal_size= size; } } spin_lock(rsv_lock); /* * shift the search start to the window near the goal block */ search_head = search_reserve_window(fs_rsv_root, start_block); /* * find_next_reservable_window() simply finds a reservable window * inside the given range(start_block, group_end_block). * * To make sure the reservation window has a free bit inside it, we * need to check the bitmap after we found a reservable window. */ retry: ret = find_next_reservable_window(search_head, my_rsv, sb, start_block, group_end_block); if (ret == -1) { if (!rsv_is_empty(&my_rsv->rsv_window)) rsv_window_remove(sb, my_rsv); spin_unlock(rsv_lock); return -1; } /* * On success, find_next_reservable_window() returns the * reservation window where there is a reservable space after it. * Before we reserve this reservable space, we need * to make sure there is at least a free block inside this region. * * searching the first free bit on the block bitmap and copy of * last committed bitmap alternatively, until we found a allocatable * block. Search start from the start block of the reservable space * we just found. */ spin_unlock(rsv_lock); first_free_block = bitmap_search_next_usable_block( my_rsv->rsv_start - group_first_block, bitmap_bh, group_end_block - group_first_block + 1); if (first_free_block < 0) { /* * no free block left on the bitmap, no point * to reserve the space. return failed. */ spin_lock(rsv_lock); if (!rsv_is_empty(&my_rsv->rsv_window)) rsv_window_remove(sb, my_rsv); spin_unlock(rsv_lock); return -1; /* failed */ } start_block = first_free_block + group_first_block; /* * check if the first free block is within the * free space we just reserved */ if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end) return 0; /* success */ /* * if the first free bit we found is out of the reservable space * continue search for next reservable space, * start from where the free block is, * we also shift the list head to where we stopped last time */ search_head = my_rsv; spin_lock(rsv_lock); goto retry; } /* * This is the main function used to allocate a new block and its reservation * window. * * Each time when a new block allocation is need, first try to allocate from * its own reservation. If it does not have a reservation window, instead of * looking for a free bit on bitmap first, then look up the reservation list to * see if it is inside somebody else's reservation window, we try to allocate a * reservation window for it starting from the goal first. Then do the block * allocation within the reservation window. * * This will avoid keeping on searching the reservation list again and * again when somebody is looking for a free block (without * reservation), and there are lots of free blocks, but they are all * being reserved. * * We use a sorted double linked list for the per-filesystem reservation list. * The insert, remove and find a free space(non-reserved) operations for the * sorted double linked list should be fast. * */ static int ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle, unsigned int group, struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window_node * my_rsv, int *errp) { unsigned long group_first_block; int ret = 0; int fatal; *errp = 0; /* * Make sure we use undo access for the bitmap, because it is critical * that we do the frozen_data COW on bitmap buffers in all cases even * if the buffer is in BJ_Forget state in the committing transaction. */ BUFFER_TRACE(bitmap_bh, "get undo access for new block"); fatal = ext3_journal_get_undo_access(handle, bitmap_bh); if (fatal) { *errp = fatal; return -1; } /* * we don't deal with reservation when * filesystem is mounted without reservation * or the file is not a regular file * or last attempt to allocate a block with reservation turned on failed */ if (my_rsv == NULL ) { ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL); goto out; } /* * goal is a group relative block number (if there is a goal) * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb) * first block is a filesystem wide block number * first block is the block number of the first block in this group */ group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) + group * EXT3_BLOCKS_PER_GROUP(sb); /* * Basically we will allocate a new block from inode's reservation * window. * * We need to allocate a new reservation window, if: * a) inode does not have a reservation window; or * b) last attempt to allocate a block from existing reservation * failed; or * c) we come here with a goal and with a reservation window * * We do not need to allocate a new reservation window if we come here * at the beginning with a goal and the goal is inside the window, or * we don't have a goal but already have a reservation window. * then we could go to allocate from the reservation window directly. */ while (1) { if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) || !goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) { ret = alloc_new_reservation(my_rsv, goal, sb, group, bitmap_bh); if (ret < 0) break; /* failed */ if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) goal = -1; } if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb)) || (my_rsv->rsv_end < group_first_block)) BUG(); ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, &my_rsv->rsv_window); if (ret >= 0) { my_rsv->rsv_alloc_hit++; break; /* succeed */ } } out: if (ret >= 0) { BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for " "bitmap block"); fatal = ext3_journal_dirty_metadata(handle, bitmap_bh); if (fatal) { *errp = fatal; return -1; } return ret; } BUFFER_TRACE(bitmap_bh, "journal_release_buffer"); ext3_journal_release_buffer(handle, bitmap_bh); return ret; } static int ext3_has_free_blocks(struct ext3_sb_info *sbi) { int free_blocks, root_blocks; free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter); root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count); if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) && sbi->s_resuid != current->fsuid && (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) { return 0; } return 1; } /* * ext3_should_retry_alloc() is called when ENOSPC is returned, and if * it is profitable to retry the operation, this function will wait * for the current or commiting transaction to complete, and then * return TRUE. */ int ext3_should_retry_alloc(struct super_block *sb, int *retries) { if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3) return 0; jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); return journal_force_commit_nested(EXT3_SB(sb)->s_journal); } /* * ext3_new_block uses a goal block to assist allocation. If the goal is * free, or there is a free block within 32 blocks of the goal, that block * is allocated. Otherwise a forward search is made for a free block; within * each block group the search first looks for an entire free byte in the block * bitmap, and then for any free bit if that fails. * This function also updates quota and i_blocks field. */ int ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal, int *errp) { struct buffer_head *bitmap_bh = NULL; struct buffer_head *gdp_bh; int group_no; int goal_group; int ret_block; int bgi; /* blockgroup iteration index */ int target_block; int fatal = 0, err; int performed_allocation = 0; int free_blocks; struct super_block *sb; struct ext3_group_desc *gdp; struct ext3_super_block *es; struct ext3_sb_info *sbi; struct ext3_reserve_window_node *my_rsv = NULL; struct ext3_block_alloc_info *block_i; unsigned short windowsz = 0; #ifdef EXT3FS_DEBUG static int goal_hits, goal_attempts; #endif unsigned long ngroups; *errp = -ENOSPC; sb = inode->i_sb; if (!sb) { printk("ext3_new_block: nonexistent device"); return 0; } /* * Check quota for allocation of this block. */ if (DQUOT_ALLOC_BLOCK(inode, 1)) { *errp = -EDQUOT; return 0; } sbi = EXT3_SB(sb); es = EXT3_SB(sb)->s_es; ext3_debug("goal=%lu.\n", goal); /* * Allocate a block from reservation only when * filesystem is mounted with reservation(default,-o reservation), and * it's a regular file, and * the desired window size is greater than 0 (One could use ioctl * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off * reservation on that particular file) */ block_i = EXT3_I(inode)->i_block_alloc_info; if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0)) my_rsv = &block_i->rsv_window_node; if (!ext3_has_free_blocks(sbi)) { *errp = -ENOSPC; goto out; } /* * First, test whether the goal block is free. */ if (goal < le32_to_cpu(es->s_first_data_block) || goal >= le32_to_cpu(es->s_blocks_count)) goal = le32_to_cpu(es->s_first_data_block); group_no = (goal - le32_to_cpu(es->s_first_data_block)) / EXT3_BLOCKS_PER_GROUP(sb); gdp = ext3_get_group_desc(sb, group_no, &gdp_bh); if (!gdp) goto io_error; goal_group = group_no; retry: free_blocks = le16_to_cpu(gdp->bg_free_blocks_count); /* * if there is not enough free blocks to make a new resevation * turn off reservation for this allocation */ if (my_rsv && (free_blocks < windowsz) && (rsv_is_empty(&my_rsv->rsv_window))) my_rsv = NULL; if (free_blocks > 0) { ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) % EXT3_BLOCKS_PER_GROUP(sb)); bitmap_bh = read_block_bitmap(sb, group_no); if (!bitmap_bh) goto io_error; ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no, bitmap_bh, ret_block, my_rsv, &fatal); if (fatal) goto out; if (ret_block >= 0) goto allocated; } ngroups = EXT3_SB(sb)->s_groups_count; smp_rmb(); /* * Now search the rest of the groups. We assume that * i and gdp correctly point to the last group visited. */ for (bgi = 0; bgi < ngroups; bgi++) { group_no++; if (group_no >= ngroups) group_no = 0; gdp = ext3_get_group_desc(sb, group_no, &gdp_bh); if (!gdp) { *errp = -EIO; goto out; } free_blocks = le16_to_cpu(gdp->bg_free_blocks_count); /* * skip this group if the number of * free blocks is less than half of the reservation * window size. */ if (free_blocks <= (windowsz/2)) continue; brelse(bitmap_bh); bitmap_bh = read_block_bitmap(sb, group_no); if (!bitmap_bh) goto io_error; ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no, bitmap_bh, -1, my_rsv, &fatal); if (fatal) goto out; if (ret_block >= 0) goto allocated; } /* * We may end up a bogus ealier ENOSPC error due to * filesystem is "full" of reservations, but * there maybe indeed free blocks avaliable on disk * In this case, we just forget about the reservations * just do block allocation as without reservations. */ if (my_rsv) { my_rsv = NULL; group_no = goal_group; goto retry; } /* No space left on the device */ *errp = -ENOSPC; goto out; allocated: ext3_debug("using block group %d(%d)\n", group_no, gdp->bg_free_blocks_count); BUFFER_TRACE(gdp_bh, "get_write_access"); fatal = ext3_journal_get_write_access(handle, gdp_bh); if (fatal) goto out; target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb) + le32_to_cpu(es->s_first_data_block); if (target_block == le32_to_cpu(gdp->bg_block_bitmap) || target_block == le32_to_cpu(gdp->bg_inode_bitmap) || in_range(target_block, le32_to_cpu(gdp->bg_inode_table), EXT3_SB(sb)->s_itb_per_group)) ext3_error(sb, "ext3_new_block", "Allocating block in system zone - " "block = %u", target_block); performed_allocation = 1; #ifdef CONFIG_JBD_DEBUG { struct buffer_head *debug_bh; /* Record bitmap buffer state in the newly allocated block */ debug_bh = sb_find_get_block(sb, target_block); if (debug_bh) { BUFFER_TRACE(debug_bh, "state when allocated"); BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state"); brelse(debug_bh); } } jbd_lock_bh_state(bitmap_bh); spin_lock(sb_bgl_lock(sbi, group_no)); if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) { if (ext3_test_bit(ret_block, bh2jh(bitmap_bh)->b_committed_data)) { printk("%s: block was unexpectedly set in " "b_committed_data\n", __FUNCTION__); } } ext3_debug("found bit %d\n", ret_block); spin_unlock(sb_bgl_lock(sbi, group_no)); jbd_unlock_bh_state(bitmap_bh); #endif /* ret_block was blockgroup-relative. Now it becomes fs-relative */ ret_block = target_block; if (ret_block >= le32_to_cpu(es->s_blocks_count)) { ext3_error(sb, "ext3_new_block", "block(%d) >= blocks count(%d) - " "block_group = %d, es == %p ", ret_block, le32_to_cpu(es->s_blocks_count), group_no, es); goto out; } /* * It is up to the caller to add the new buffer to a journal * list of some description. We don't know in advance whether * the caller wants to use it as metadata or data. */ ext3_debug("allocating block %d. Goal hits %d of %d.\n", ret_block, goal_hits, goal_attempts); spin_lock(sb_bgl_lock(sbi, group_no)); gdp->bg_free_blocks_count = cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1); spin_unlock(sb_bgl_lock(sbi, group_no)); percpu_counter_mod(&sbi->s_freeblocks_counter, -1); BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor"); err = ext3_journal_dirty_metadata(handle, gdp_bh); if (!fatal) fatal = err; sb->s_dirt = 1; if (fatal) goto out; *errp = 0; brelse(bitmap_bh); return ret_block; io_error: *errp = -EIO; out: if (fatal) { *errp = fatal; ext3_std_error(sb, fatal); } /* * Undo the block allocation */ if (!performed_allocation) DQUOT_FREE_BLOCK(inode, 1); brelse(bitmap_bh); return 0; } unsigned long ext3_count_free_blocks(struct super_block *sb) { unsigned long desc_count; struct ext3_group_desc *gdp; int i; unsigned long ngroups = EXT3_SB(sb)->s_groups_count; #ifdef EXT3FS_DEBUG struct ext3_super_block *es; unsigned long bitmap_count, x; struct buffer_head *bitmap_bh = NULL; es = EXT3_SB(sb)->s_es; desc_count = 0; bitmap_count = 0; gdp = NULL; smp_rmb(); for (i = 0; i < ngroups; i++) { gdp = ext3_get_group_desc(sb, i, NULL); if (!gdp) continue; desc_count += le16_to_cpu(gdp->bg_free_blocks_count); brelse(bitmap_bh); bitmap_bh = read_block_bitmap(sb, i); if (bitmap_bh == NULL) continue; x = ext3_count_free(bitmap_bh, sb->s_blocksize); printk("group %d: stored = %d, counted = %lu\n", i, le16_to_cpu(gdp->bg_free_blocks_count), x); bitmap_count += x; } brelse(bitmap_bh); printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n", le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count); return bitmap_count; #else desc_count = 0; smp_rmb(); for (i = 0; i < ngroups; i++) { gdp = ext3_get_group_desc(sb, i, NULL); if (!gdp) continue; desc_count += le16_to_cpu(gdp->bg_free_blocks_count); } return desc_count; #endif } static inline int block_in_use(unsigned long block, struct super_block *sb, unsigned char *map) { return ext3_test_bit ((block - le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) % EXT3_BLOCKS_PER_GROUP(sb), map); } static inline int test_root(int a, int b) { int num = b; while (a > num) num *= b; return num == a; } static int ext3_group_sparse(int group) { if (group <= 1) return 1; if (!(group & 1)) return 0; return (test_root(group, 7) || test_root(group, 5) || test_root(group, 3)); } /** * ext3_bg_has_super - number of blocks used by the superblock in group * @sb: superblock for filesystem * @group: group number to check * * Return the number of blocks used by the superblock (primary or backup) * in this group. Currently this will be only 0 or 1. */ int ext3_bg_has_super(struct super_block *sb, int group) { if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&& !ext3_group_sparse(group)) return 0; return 1; } /** * ext3_bg_num_gdb - number of blocks used by the group table in group * @sb: superblock for filesystem * @group: group number to check * * Return the number of blocks used by the group descriptor table * (primary or backup) in this group. In the future there may be a * different number of descriptor blocks in each group. */ unsigned long ext3_bg_num_gdb(struct super_block *sb, int group) { if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&& !ext3_group_sparse(group)) return 0; return EXT3_SB(sb)->s_gdb_count; }