WSL2-Linux-Kernel/fs/ext4/dir.c

516 строки
13 KiB
C
Исходник Обычный вид История

/*
* 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, /* BKL held */
.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 = le16_to_cpu(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) {
unsigned long 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);
[PATCH] handle ext4 directory corruption better I've been using Steve Grubb's purely evil "fsfuzzer" tool, at http://people.redhat.com/sgrubb/files/fsfuzzer-0.4.tar.gz Basically it makes a filesystem, splats some random bits over it, then tries to mount it and do some simple filesystem actions. At best, the filesystem catches the corruption gracefully. At worst, things spin out of control. As you might guess, we found a couple places in ext4 where things spin out of control :) First, we had a corrupted directory that was never checked for consistency... it was corrupt, and pointed to another bad "entry" of length 0. The for() loop looped forever, since the length of ext4_next_entry(de) was 0, and we kept looking at the same pointer over and over and over and over... I modeled this check and subsequent action on what is done for other directory types in ext4_readdir... (adding this check adds some computational expense; I am testing a followup patch to reduce the number of times we check and re-check these directory entries, in all cases. Thanks for the idea, Andreas). Next we had a root directory inode which had a corrupted size, claimed to be > 200M on a 4M filesystem. There was only really 1 block in the directory, but because the size was so large, readdir kept coming back for more, spewing thousands of printk's along the way. Per Andreas' suggestion, if we're in this read error condition and we're trying to read an offset which is greater than i_blocks worth of bytes, stop trying, and break out of the loop. With these two changes fsfuzz test survives quite well on ext4. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 07:36:28 +03:00
/* 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 (le16_to_cpu(de->rec_len) <
EXT4_DIR_REC_LEN(1))
break;
i += le16_to_cpu(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 += le16_to_cpu(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 += le16_to_cpu(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;
}