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|
/*
* 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/buffer_head.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
#include "ext4.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 = ext4_llseek,
.read = generic_read_dir,
.readdir = ext4_readdir, /* we take BKL. needed?*/
.unlocked_ioctl = ext4_ioctl,
#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, unsigned int line,
struct inode *dir,
struct ext4_dir_entry_2 *de,
struct buffer_head *bh,
unsigned int offset)
{
const char *error_msg = NULL;
const int rlen = ext4_rec_len_from_disk(de->rec_len,
dir->i_sb->s_blocksize);
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_inode(dir, function, line, bh->b_blocknr,
"bad entry in directory: %s - "
"offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
error_msg, (unsigned) (offset%bh->b_size), offset,
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 int 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;
int dir_has_error = 0;
sb = inode->i_sb;
if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
EXT4_FEATURE_COMPAT_DIR_INDEX) &&
((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
((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_clear_inode_flag(filp->f_path.dentry->d_inode,
EXT4_INODE_INDEX);
}
stored = 0;
offset = filp->f_pos & (sb->s_blocksize - 1);
while (!error && !stored && filp->f_pos < inode->i_size) {
struct ext4_map_blocks map;
struct buffer_head *bh = NULL;
map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
map.m_len = 1;
err = ext4_map_blocks(NULL, inode, &map, 0);
if (err > 0) {
pgoff_t index = map.m_pblk >>
(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, map.m_lblk, 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) {
EXT4_ERROR_INODE(inode, "directory "
"contains a hole at offset %Lu",
(unsigned long long) filp->f_pos);
dir_has_error = 1;
}
/* 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,
sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
break;
i += ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize);
}
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(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;
g
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