diff options
Diffstat (limited to 'kernel/fs/ext3/dir.c')
-rw-r--r-- | kernel/fs/ext3/dir.c | 537 |
1 files changed, 537 insertions, 0 deletions
diff --git a/kernel/fs/ext3/dir.c b/kernel/fs/ext3/dir.c new file mode 100644 index 000000000..17742eed2 --- /dev/null +++ b/kernel/fs/ext3/dir.c @@ -0,0 +1,537 @@ +/* + * linux/fs/ext3/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 + * + * ext3 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/compat.h> +#include "ext3.h" + +static unsigned char ext3_filetype_table[] = { + DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK +}; + +static int ext3_dx_readdir(struct file *, struct dir_context *); + +static unsigned char get_dtype(struct super_block *sb, int filetype) +{ + if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) || + (filetype >= EXT3_FT_MAX)) + return DT_UNKNOWN; + + return (ext3_filetype_table[filetype]); +} + +/** + * Check if the given dir-inode refers to an htree-indexed directory + * (or a directory which could potentially get converted to use htree + * indexing). + * + * Return 1 if it is a dx dir, 0 if not + */ +static int is_dx_dir(struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + + if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb, + EXT3_FEATURE_COMPAT_DIR_INDEX) && + ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) || + ((inode->i_size >> sb->s_blocksize_bits) == 1))) + return 1; + + return 0; +} + +int ext3_check_dir_entry (const char * function, struct inode * dir, + struct ext3_dir_entry_2 * de, + struct buffer_head * bh, + unsigned long offset) +{ + const char * error_msg = NULL; + const int rlen = ext3_rec_len_from_disk(de->rec_len); + + if (unlikely(rlen < EXT3_DIR_REC_LEN(1))) + error_msg = "rec_len is smaller than minimal"; + else if (unlikely(rlen % 4 != 0)) + error_msg = "rec_len % 4 != 0"; + else if (unlikely(rlen < EXT3_DIR_REC_LEN(de->name_len))) + error_msg = "rec_len is too small for name_len"; + else if (unlikely((((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize))) + error_msg = "directory entry across blocks"; + else if (unlikely(le32_to_cpu(de->inode) > + le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))) + error_msg = "inode out of bounds"; + + if (unlikely(error_msg != NULL)) + ext3_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 ext3_readdir(struct file *file, struct dir_context *ctx) +{ + unsigned long offset; + int i; + struct ext3_dir_entry_2 *de; + int err; + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + int dir_has_error = 0; + + if (is_dx_dir(inode)) { + err = ext3_dx_readdir(file, ctx); + if (err != ERR_BAD_DX_DIR) + return err; + /* + * We don't set the inode dirty flag since it's not + * critical that it get flushed back to the disk. + */ + EXT3_I(inode)->i_flags &= ~EXT3_INDEX_FL; + } + offset = ctx->pos & (sb->s_blocksize - 1); + + while (ctx->pos < inode->i_size) { + unsigned long blk = ctx->pos >> EXT3_BLOCK_SIZE_BITS(sb); + struct buffer_head map_bh; + struct buffer_head *bh = NULL; + + map_bh.b_state = 0; + err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0); + if (err > 0) { + pgoff_t index = map_bh.b_blocknr >> + (PAGE_CACHE_SHIFT - inode->i_blkbits); + if (!ra_has_index(&file->f_ra, index)) + page_cache_sync_readahead( + sb->s_bdev->bd_inode->i_mapping, + &file->f_ra, file, + index, 1); + file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; + bh = ext3_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) { + if (!dir_has_error) { + ext3_error(sb, __func__, "directory #%lu " + "contains a hole at offset %lld", + inode->i_ino, ctx->pos); + dir_has_error = 1; + } + /* corrupt size? Maybe no more blocks to read */ + if (ctx->pos > inode->i_blocks << 9) + break; + ctx->pos += sb->s_blocksize - offset; + continue; + } + + /* 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 (offset && file->f_version != inode->i_version) { + for (i = 0; i < sb->s_blocksize && i < offset; ) { + de = (struct ext3_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 (ext3_rec_len_from_disk(de->rec_len) < + EXT3_DIR_REC_LEN(1)) + break; + i += ext3_rec_len_from_disk(de->rec_len); + } + offset = i; + ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) + | offset; + file->f_version = inode->i_version; + } + + while (ctx->pos < inode->i_size + && offset < sb->s_blocksize) { + de = (struct ext3_dir_entry_2 *) (bh->b_data + offset); + if (!ext3_check_dir_entry ("ext3_readdir", inode, de, + bh, offset)) { + /* On error, skip the to the + next block. */ + ctx->pos = (ctx->pos | + (sb->s_blocksize - 1)) + 1; + break; + } + offset += ext3_rec_len_from_disk(de->rec_len); + if (le32_to_cpu(de->inode)) { + if (!dir_emit(ctx, de->name, de->name_len, + le32_to_cpu(de->inode), + get_dtype(sb, de->file_type))) { + brelse(bh); + return 0; + } + } + ctx->pos += ext3_rec_len_from_disk(de->rec_len); + } + offset = 0; + brelse (bh); + if (ctx->pos < inode->i_size) + if (!dir_relax(inode)) + return 0; + } + return 0; +} + +static inline int is_32bit_api(void) +{ +#ifdef CONFIG_COMPAT + return is_compat_task(); +#else + return (BITS_PER_LONG == 32); +#endif +} + +/* + * These functions convert from the major/minor hash to an f_pos + * value for dx directories + * + * Upper layer (for example NFS) should specify FMODE_32BITHASH or + * FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted + * directly on both 32-bit and 64-bit nodes, under such case, neither + * FMODE_32BITHASH nor FMODE_64BITHASH is specified. + */ +static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return major >> 1; + else + return ((__u64)(major >> 1) << 32) | (__u64)minor; +} + +static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return (pos << 1) & 0xffffffff; + else + return ((pos >> 32) << 1) & 0xffffffff; +} + +static inline __u32 pos2min_hash(struct file *filp, loff_t pos) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return 0; + else + return pos & 0xffffffff; +} + +/* + * Return 32- or 64-bit end-of-file for dx directories + */ +static inline loff_t ext3_get_htree_eof(struct file *filp) +{ + if ((filp->f_mode & FMODE_32BITHASH) || + (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) + return EXT3_HTREE_EOF_32BIT; + else + return EXT3_HTREE_EOF_64BIT; +} + + +/* + * ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both + * non-htree and htree directories, where the "offset" is in terms + * of the filename hash value instead of the byte offset. + * + * Because we may return a 64-bit hash that is well beyond s_maxbytes, + * we need to pass the max hash as the maximum allowable offset in + * the htree directory case. + * + * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX) + * will be invalid once the directory was converted into a dx directory + */ +static loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_mapping->host; + int dx_dir = is_dx_dir(inode); + loff_t htree_max = ext3_get_htree_eof(file); + + if (likely(dx_dir)) + return generic_file_llseek_size(file, offset, whence, + htree_max, htree_max); + else + return generic_file_llseek(file, offset, whence); +} + +/* + * 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 fname *fname, *next; + + rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) + do { + struct fname *old = fname; + fname = fname->next; + kfree(old); + } while (fname); + + *root = RB_ROOT; +} + +static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp, + loff_t pos) +{ + struct dir_private_info *p; + + p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); + if (!p) + return NULL; + p->curr_hash = pos2maj_hash(filp, pos); + p->curr_minor_hash = pos2min_hash(filp, pos); + return p; +} + +void ext3_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 ext3_htree_store_dirent(struct file *dir_file, __u32 hash, + __u32 minor_hash, + struct ext3_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 ext3_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 bool call_filldir(struct file *file, struct dir_context *ctx, + struct fname *fname) +{ + struct dir_private_info *info = file->private_data; + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + + if (!fname) { + printk("call_filldir: called with null fname?!?\n"); + return true; + } + ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); + while (fname) { + if (!dir_emit(ctx, fname->name, fname->name_len, + fname->inode, + get_dtype(sb, fname->file_type))) { + info->extra_fname = fname; + return false; + } + fname = fname->next; + } + return true; +} + +static int ext3_dx_readdir(struct file *file, struct dir_context *ctx) +{ + struct dir_private_info *info = file->private_data; + struct inode *inode = file_inode(file); + struct fname *fname; + int ret; + + if (!info) { + info = ext3_htree_create_dir_info(file, ctx->pos); + if (!info) + return -ENOMEM; + file->private_data = info; + } + + if (ctx->pos == ext3_get_htree_eof(file)) + return 0; /* EOF */ + + /* Some one has messed with f_pos; reset the world */ + if (info->last_pos != ctx->pos) { + free_rb_tree_fname(&info->root); + info->curr_node = NULL; + info->extra_fname = NULL; + info->curr_hash = pos2maj_hash(file, ctx->pos); + info->curr_minor_hash = pos2min_hash(file, ctx->pos); + } + + /* + * If there are any leftover names on the hash collision + * chain, return them first. + */ + if (info->extra_fname) { + if (!call_filldir(file, ctx, info->extra_fname)) + goto finished; + info->extra_fname = NULL; + goto next_node; + } else 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) || + (file->f_version != inode->i_version)) { + info->curr_node = NULL; + free_rb_tree_fname(&info->root); + file->f_version = inode->i_version; + ret = ext3_htree_fill_tree(file, info->curr_hash, + info->curr_minor_hash, + &info->next_hash); + if (ret < 0) + return ret; + if (ret == 0) { + ctx->pos = ext3_get_htree_eof(file); + 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(file, ctx, fname)) + break; + next_node: + info->curr_node = rb_next(info->curr_node); + if (info->curr_node) { + fname = rb_entry(info->curr_node, struct fname, + rb_hash); + info->curr_hash = fname->hash; + info->curr_minor_hash = fname->minor_hash; + } else { + if (info->next_hash == ~0) { + ctx->pos = ext3_get_htree_eof(file); + break; + } + info->curr_hash = info->next_hash; + info->curr_minor_hash = 0; + } + } +finished: + info->last_pos = ctx->pos; + return 0; +} + +static int ext3_release_dir (struct inode * inode, struct file * filp) +{ + if (filp->private_data) + ext3_htree_free_dir_info(filp->private_data); + + return 0; +} + +const struct file_operations ext3_dir_operations = { + .llseek = ext3_dir_llseek, + .read = generic_read_dir, + .iterate = ext3_readdir, + .unlocked_ioctl = ext3_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = ext3_compat_ioctl, +#endif + .fsync = ext3_sync_file, + .release = ext3_release_dir, +}; |