/* * linux/fs/ext4/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 * * ext4 directory handling functions * * Big-endian to little-endian byte-swapping/bitmaps by * David S. Miller (davem@caip.rutgers.edu), 1995 * * Hash Tree Directory indexing (c) 2001 Daniel Phillips * */ #include <linux/fs.h> #include <linux/jbd2.h> #include <linux/ext4_fs.h> #include <linux/buffer_head.h> #include <linux/slab.h> #include <linux/rbtree.h> static unsigned char ext4_filetype_table[] = { DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK }; static int ext4_readdir(struct file *, void *, filldir_t); static int ext4_dx_readdir(struct file * filp, void * dirent, filldir_t filldir); static int ext4_release_dir (struct inode * inode, struct file * filp); const struct file_operations ext4_dir_operations = { .llseek = generic_file_llseek, .read = generic_read_dir, .readdir = ext4_readdir, /* we take BKL. needed?*/ .ioctl = ext4_ioctl, /* BKL held */ #ifdef CONFIG_COMPAT .compat_ioctl = ext4_compat_ioctl, #endif .fsync = ext4_sync_file, .release = ext4_release_dir, }; static unsigned char get_dtype(struct super_block *sb, int filetype) { if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || (filetype >= EXT4_FT_MAX)) return DT_UNKNOWN; return (ext4_filetype_table[filetype]); } int ext4_check_dir_entry (const char * function, struct inode * dir, struct ext4_dir_entry_2 * de, struct buffer_head * bh, unsigned long offset) { const char * error_msg = NULL; const int rlen = ext4_rec_len_from_disk(de->rec_len); if (rlen < EXT4_DIR_REC_LEN(1)) error_msg = "rec_len is smaller than minimal"; else if (rlen % 4 != 0) error_msg = "rec_len % 4 != 0"; else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) error_msg = "rec_len is too small for name_len"; else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) error_msg = "directory entry across blocks"; else if (le32_to_cpu(de->inode) > le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) error_msg = "inode out of bounds"; if (error_msg != NULL) ext4_error (dir->i_sb, function, "bad entry in directory #%lu: %s - " "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", dir->i_ino, error_msg, offset, (unsigned long) le32_to_cpu(de->inode), rlen, de->name_len); return error_msg == NULL ? 1 : 0; } static int ext4_readdir(struct file * filp, void * dirent, filldir_t filldir) { int error = 0; unsigned long offset; int i, stored; struct ext4_dir_entry_2 *de; struct super_block *sb; int err; struct inode *inode = filp->f_path.dentry->d_inode; int ret = 0; sb = inode->i_sb; if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, EXT4_FEATURE_COMPAT_DIR_INDEX) && ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || ((inode->i_size >> sb->s_blocksize_bits) == 1))) { err = ext4_dx_readdir(filp, dirent, filldir); if (err != ERR_BAD_DX_DIR) { ret = err; goto out; } /* * We don't set the inode dirty flag since it's not * critical that it get flushed back to the disk. */ EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; } stored = 0; offset = filp->f_pos & (sb->s_blocksize - 1); while (!error && !stored && filp->f_pos < inode->i_size) { ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); struct buffer_head map_bh; struct buffer_head *bh = NULL; map_bh.b_state = 0; err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0); if (err > 0) { pgoff_t index = map_bh.b_blocknr >> (PAGE_CACHE_SHIFT - inode->i_blkbits); if (!ra_has_index(&filp->f_ra, index)) page_cache_sync_readahead( sb->s_bdev->bd_inode->i_mapping, &filp->f_ra, filp, index, 1); filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; bh = ext4_bread(NULL, inode, blk, 0, &err); } /* * We ignore I/O errors on directories so users have a chance * of recovering data when there's a bad sector */ if (!bh) { ext4_error (sb, "ext4_readdir", "directory #%lu contains a hole at offset %lu", inode->i_ino, (unsigned long)filp->f_pos); /* corrupt size? Maybe no more blocks to read */ if (filp->f_pos > inode->i_blocks << 9) break; filp->f_pos += sb->s_blocksize - offset; continue; } revalidate: /* If the dir block has changed since the last call to * readdir(2), then we might be pointing to an invalid * dirent right now. Scan from the start of the block * to make sure. */ if (filp->f_version != inode->i_version) { for (i = 0; i < sb->s_blocksize && i < offset; ) { de = (struct ext4_dir_entry_2 *) (bh->b_data + i); /* It's too expensive to do a full * dirent test each time round this * loop, but we do have to test at * least that it is non-zero. A * failure will be detected in the * dirent test below. */ if (ext4_rec_len_from_disk(de->rec_len) < EXT4_DIR_REC_LEN(1)) break; i += ext4_rec_len_from_disk(de->rec_len); } offset = i; filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) | offset; filp->f_version = inode->i_version; } while (!error && filp->f_pos < inode->i_size && offset < sb->s_blocksize) { de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); if (!ext4_check_dir_entry ("ext4_readdir", inode, de, bh, offset)) { /* * On error, skip the f_pos to the next block */ filp->f_pos = (filp->f_pos | (sb->s_blocksize - 1)) + 1; brelse (bh); ret = stored; goto out; } offset += ext4_rec_len_from_disk(de->rec_len); if (le32_to_cpu(de->inode)) { /* We might block in the next section * if the data destination is * currently swapped out. So, use a * version stamp to detect whether or * not the directory has been modified * during the copy operation. */ u64 version = filp->f_version; error = filldir(dirent, de->name, de->name_len, filp->f_pos, le32_to_cpu(de->inode), get_dtype(sb, de->file_type)); if (error) break; if (version != filp->f_version) goto revalidate; stored ++; } filp->f_pos += ext4_rec_len_from_disk(de->rec_len); } offset = 0; brelse (bh); } out: return ret; } /* * These functions convert from the major/minor hash to an f_pos * value. * * Currently we only use major hash numer. This is unfortunate, but * on 32-bit machines, the same VFS interface is used for lseek and * llseek, so if we use the 64 bit offset, then the 32-bit versions of * lseek/telldir/seekdir will blow out spectacularly, and from within * the ext2 low-level routine, we don't know if we're being called by * a 64-bit version of the system call or the 32-bit version of the * system call. Worse yet, NFSv2 only allows for a 32-bit readdir * cookie. Sigh. */ #define hash2pos(major, minor) (major >> 1) #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) #define pos2min_hash(pos) (0) /* * This structure holds the nodes of the red-black tree used to store * the directory entry in hash order. */ struct fname { __u32 hash; __u32 minor_hash; struct rb_node rb_hash; struct fname *next; __u32 inode; __u8 name_len; __u8 file_type; char name[0]; }; /* * This functoin implements a non-recursive way of freeing all of the * nodes in the red-black tree. */ static void free_rb_tree_fname(struct rb_root *root) { struct rb_node *n = root->rb_node; struct rb_node *parent; struct fname *fname; while (n) { /* Do the node's children first */ if ((n)->rb_left) { n = n->rb_left; continue; } if (n->rb_right) { n = n->rb_right; continue; } /* * The node has no children; free it, and then zero * out parent's link to it. Finally go to the * beginning of the loop and try to free the parent * node. */ parent = rb_parent(n); fname = rb_entry(n, struct fname, rb_hash); while (fname) { struct fname * old = fname; fname = fname->next; kfree (old); } if (!parent) root->rb_node = NULL; else if (parent->rb_left == n) parent->rb_left = NULL; else if (parent->rb_right == n) parent->rb_right = NULL; n = parent; } root->rb_node = NULL; } static struct dir_private_info *create_dir_info(loff_t pos) { struct dir_private_info *p; p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); if (!p) return NULL; p->root.rb_node = NULL; p->curr_node = NULL; p->extra_fname = NULL; p->last_pos = 0; p->curr_hash = pos2maj_hash(pos); p->curr_minor_hash = pos2min_hash(pos); p->next_hash = 0; return p; } void ext4_htree_free_dir_info(struct dir_private_info *p) { free_rb_tree_fname(&p->root); kfree(p); } /* * Given a directory entry, enter it into the fname rb tree. */ int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, __u32 minor_hash, struct ext4_dir_entry_2 *dirent) { struct rb_node **p, *parent = NULL; struct fname * fname, *new_fn; struct dir_private_info *info; int len; info = (struct dir_private_info *) dir_file->private_data; p = &info->root.rb_node; /* Create and allocate the fname structure */ len = sizeof(struct fname) + dirent->name_len + 1; new_fn = kzalloc(len, GFP_KERNEL); if (!new_fn) return -ENOMEM; new_fn->hash = hash; new_fn->minor_hash = minor_hash; new_fn->inode = le32_to_cpu(dirent->inode); new_fn->name_len = dirent->name_len; new_fn->file_type = dirent->file_type; memcpy(new_fn->name, dirent->name, dirent->name_len); new_fn->name[dirent->name_len] = 0; while (*p) { parent = *p; fname = rb_entry(parent, struct fname, rb_hash); /* * If the hash and minor hash match up, then we put * them on a linked list. This rarely happens... */ if ((new_fn->hash == fname->hash) && (new_fn->minor_hash == fname->minor_hash)) { new_fn->next = fname->next; fname->next = new_fn; return 0; } if (new_fn->hash < fname->hash) p = &(*p)->rb_left; else if (new_fn->hash > fname->hash) p = &(*p)->rb_right; else if (new_fn->minor_hash < fname->minor_hash) p = &(*p)->rb_left; else /* if (new_fn->minor_hash > fname->minor_hash) */ p = &(*p)->rb_right; } rb_link_node(&new_fn->rb_hash, parent, p); rb_insert_color(&new_fn->rb_hash, &info->root); return 0; } /* * This is a helper function for ext4_dx_readdir. It calls filldir * for all entres on the fname linked list. (Normally there is only * one entry on the linked list, unless there are 62 bit hash collisions.) */ static int call_filldir(struct file * filp, void * dirent, filldir_t filldir, struct fname *fname) { struct dir_private_info *info = filp->private_data; loff_t curr_pos; struct inode *inode = filp->f_path.dentry->d_inode; struct super_block * sb; int error; sb = inode->i_sb; if (!fname) { printk("call_filldir: called with null fname?!?\n"); return 0; } curr_pos = hash2pos(fname->hash, fname->minor_hash); while (fname) { error = filldir(dirent, fname->name, fname->name_len, curr_pos, fname->inode, get_dtype(sb, fname->file_type)); if (error) { filp->f_pos = curr_pos; info->extra_fname = fname->next; return error; } fname = fname->next; } return 0; } static int ext4_dx_readdir(struct file * filp, void * dirent, filldir_t filldir) { struct dir_private_info *info = filp->private_data; struct inode *inode = filp->f_path.dentry->d_inode; struct fname *fname; int ret; if (!info) { info = create_dir_info(filp->f_pos); if (!info) return -ENOMEM; filp->private_data = info; } if (filp->f_pos == EXT4_HTREE_EOF) return 0; /* EOF */ /* Some one has messed with f_pos; reset the world */ if (info->last_pos != filp->f_pos) { free_rb_tree_fname(&info->root); info->curr_node = NULL; info->extra_fname = NULL; info->curr_hash = pos2maj_hash(filp->f_pos); info->curr_minor_hash = pos2min_hash(filp->f_pos); } /* * If there are any leftover names on the hash collision * chain, return them first. */ if (info->extra_fname && call_filldir(filp, dirent, filldir, info->extra_fname)) goto finished; if (!info->curr_node) info->curr_node = rb_first(&info->root); while (1) { /* * Fill the rbtree if we have no more entries, * or the inode has changed since we last read in the * cached entries. */ if ((!info->curr_node) || (filp->f_version != inode->i_version)) { info->curr_node = NULL; free_rb_tree_fname(&info->root); filp->f_version = inode->i_version; ret = ext4_htree_fill_tree(filp, info->curr_hash, info->curr_minor_hash, &info->next_hash); if (ret < 0) return ret; if (ret == 0) { filp->f_pos = EXT4_HTREE_EOF; break; } info->curr_node = rb_first(&info->root); } fname = rb_entry(info->curr_node, struct fname, rb_hash); info->curr_hash = fname->hash; info->curr_minor_hash = fname->minor_hash; if (call_filldir(filp, dirent, filldir, fname)) break; info->curr_node = rb_next(info->curr_node); if (!info->curr_node) { if (info->next_hash == ~0) { filp->f_pos = EXT4_HTREE_EOF; break; } info->curr_hash = info->next_hash; info->curr_minor_hash = 0; } } finished: info->last_pos = filp->f_pos; return 0; } static int ext4_release_dir (struct inode * inode, struct file * filp) { if (filp->private_data) ext4_htree_free_dir_info(filp->private_data); return 0; }