original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/ext3/namei.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/namei.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Big-endian to little-endian byte-swapping/bitmaps by
* David S. Miller (davem@caip.rutgers.edu), 1995
* Directory entry file type support and forward compatibility hooks
* for B-tree directories by Theodore Ts'o (tytso@mit.edu), 1998
* Hash Tree Directory indexing (c)
* Daniel Phillips, 2001
* Hash Tree Directory indexing porting
* Christopher Li, 2002
* Hash Tree Directory indexing cleanup
* Theodore Ts'o, 2002
*/
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/jbd.h>
#include <linux/time.h>
#include <linux/ext3_fs.h>
#include <linux/ext3_jbd.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/bio.h>
#include "namei.h"
#include "xattr.h"
#include "acl.h"
/*
* define how far ahead to read directories while searching them.
*/
#define NAMEI_RA_CHUNKS 2
#define NAMEI_RA_BLOCKS 4
#define NAMEI_RA_SIZE (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
#define NAMEI_RA_INDEX(c,b) (((c) * NAMEI_RA_BLOCKS) + (b))
static struct buffer_head *ext3_append(handle_t *handle,
struct inode *inode,
u32 *block, int *err)
{
struct buffer_head *bh;
*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
bh = ext3_bread(handle, inode, *block, 1, err);
if (bh) {
inode->i_size += inode->i_sb->s_blocksize;
EXT3_I(inode)->i_disksize = inode->i_size;
*err = ext3_journal_get_write_access(handle, bh);
if (*err) {
brelse(bh);
bh = NULL;
}
}
return bh;
}
#ifndef assert
#define assert(test) J_ASSERT(test)
#endif
#ifdef DX_DEBUG
#define dxtrace(command) command
#else
#define dxtrace(command)
#endif
struct fake_dirent
{
__le32 inode;
__le16 rec_len;
u8 name_len;
u8 file_type;
};
struct dx_countlimit
{
__le16 limit;
__le16 count;
};
struct dx_entry
{
__le32 hash;
__le32 block;
};
/*
* dx_root_info is laid out so that if it should somehow get overlaid by a
* dirent the two low bits of the hash version will be zero. Therefore, the
* hash version mod 4 should never be 0. Sincerely, the paranoia department.
*/
struct dx_root
{
struct fake_dirent dot;
char dot_name[4];
struct fake_dirent dotdot;
char dotdot_name[4];
struct dx_root_info
{
__le32 reserved_zero;
u8 hash_version;
u8 info_length; /* 8 */
u8 indirect_levels;
u8 unused_flags;
}
info;
struct dx_entry entries[0];
};
struct dx_node
{
struct fake_dirent fake;
struct dx_entry entries[0];
};
struct dx_frame
{
struct buffer_head *bh;
struct dx_entry *entries;
struct dx_entry *at;
};
struct dx_map_entry
{
u32 hash;
ext34: ensure do_split leaves enough free space in both blocks The do_split() function for htree dir blocks is intended to split a leaf block to make room for a new entry. It sorts the entries in the original block by hash value, then moves the last half of the entries to the new block - without accounting for how much space this actually moves. (IOW, it moves half of the entry *count* not half of the entry *space*). If by chance we have both large & small entries, and we move only the smallest entries, and we have a large new entry to insert, we may not have created enough space for it. The patch below stores each record size when calculating the dx_map, and then walks the hash-sorted dx_map, calculating how many entries must be moved to more evenly split the existing entries between the old block and the new block, guaranteeing enough space for the new entry. The dx_map "offs" member is reduced to u16 so that the overall map size does not change - it is temporarily stored at the end of the new block, and if it grows too large it may be overwritten. By making offs and size both u16, we won't grow the map size. Also add a few comments to the functions involved. This fixes the testcase reported by hooanon05@yahoo.co.jp on the linux-ext4 list, "ext3 dir_index causes an error" Thanks to Andreas Dilger for discussing the problem & solution with me. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Tested-by: Junjiro Okajima <hooanon05@yahoo.co.jp> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <linux-ext4@vger.kernel.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
15 years ago
u16 offs;
u16 size;
};
static inline unsigned dx_get_block (struct dx_entry *entry);
static void dx_set_block (struct dx_entry *entry, unsigned value);
static inline unsigned dx_get_hash (struct dx_entry *entry);
static void dx_set_hash (struct dx_entry *entry, unsigned value);
static unsigned dx_get_count (struct dx_entry *entries);
static unsigned dx_get_limit (struct dx_entry *entries);
static void dx_set_count (struct dx_entry *entries, unsigned value);
static void dx_set_limit (struct dx_entry *entries, unsigned value);
static unsigned dx_root_limit (struct inode *dir, unsigned infosize);
static unsigned dx_node_limit (struct inode *dir);
static struct dx_frame *dx_probe(struct qstr *entry,
struct inode *dir,
struct dx_hash_info *hinfo,
struct dx_frame *frame,
int *err);
static void dx_release (struct dx_frame *frames);
static int dx_make_map(struct ext3_dir_entry_2 *de, unsigned blocksize,
struct dx_hash_info *hinfo, struct dx_map_entry map[]);
static void dx_sort_map(struct dx_map_entry *map, unsigned count);
static struct ext3_dir_entry_2 *dx_move_dirents (char *from, char *to,
struct dx_map_entry *offsets, int count);
static struct ext3_dir_entry_2 *dx_pack_dirents(char *base, unsigned blocksize);
static void dx_insert_block (struct dx_frame *frame, u32 hash, u32 block);
static int ext3_htree_next_block(struct inode *dir, __u32 hash,
struct dx_frame *frame,
struct dx_frame *frames,
__u32 *start_hash);
static struct buffer_head * ext3_dx_find_entry(struct inode *dir,
struct qstr *entry, struct ext3_dir_entry_2 **res_dir,
int *err);
static int ext3_dx_add_entry(handle_t *handle, struct dentry *dentry,
struct inode *inode);
/*
* p is at least 6 bytes before the end of page
*/
static inline struct ext3_dir_entry_2 *
ext3_next_entry(struct ext3_dir_entry_2 *p)
{
return (struct ext3_dir_entry_2 *)((char *)p +
ext3_rec_len_from_disk(p->rec_len));
}
/*
* Future: use high four bits of block for coalesce-on-delete flags
* Mask them off for now.
*/
static inline unsigned dx_get_block (struct dx_entry *entry)
{
return le32_to_cpu(entry->block) & 0x00ffffff;
}
static inline void dx_set_block (struct dx_entry *entry, unsigned value)
{
entry->block = cpu_to_le32(value);
}
static inline unsigned dx_get_hash (struct dx_entry *entry)
{
return le32_to_cpu(entry->hash);
}
static inline void dx_set_hash (struct dx_entry *entry, unsigned value)
{
entry->hash = cpu_to_le32(value);
}
static inline unsigned dx_get_count (struct dx_entry *entries)
{
return le16_to_cpu(((struct dx_countlimit *) entries)->count);
}
static inline unsigned dx_get_limit (struct dx_entry *entries)
{
return le16_to_cpu(((struct dx_countlimit *) entries)->limit);
}
static inline void dx_set_count (struct dx_entry *entries, unsigned value)
{
((struct dx_countlimit *) entries)->count = cpu_to_le16(value);
}
static inline void dx_set_limit (struct dx_entry *entries, unsigned value)
{
((struct dx_countlimit *) entries)->limit = cpu_to_le16(value);
}
static inline unsigned dx_root_limit (struct inode *dir, unsigned infosize)
{
unsigned entry_space = dir->i_sb->s_blocksize - EXT3_DIR_REC_LEN(1) -
EXT3_DIR_REC_LEN(2) - infosize;
return entry_space / sizeof(struct dx_entry);
}
static inline unsigned dx_node_limit (struct inode *dir)
{
unsigned entry_space = dir->i_sb->s_blocksize - EXT3_DIR_REC_LEN(0);
return entry_space / sizeof(struct dx_entry);
}
/*
* Debug
*/
#ifdef DX_DEBUG
static void dx_show_index (char * label, struct dx_entry *entries)
{
int i, n = dx_get_count (entries);
printk("%s index ", label);
for (i = 0; i < n; i++)
{
printk("%x->%u ", i? dx_get_hash(entries + i): 0, dx_get_block(entries + i));
}
printk("\n");
}
struct stats
{
unsigned names;
unsigned space;
unsigned bcount;
};
static struct stats dx_show_leaf(struct dx_hash_info *hinfo, struct ext3_dir_entry_2 *de,
int size, int show_names)
{
unsigned names = 0, space = 0;
char *base = (char *) de;
struct dx_hash_info h = *hinfo;
printk("names: ");
while ((char *) de < base + size)
{
if (de->inode)
{
if (show_names)
{
int len = de->name_len;
char *name = de->name;
while (len--) printk("%c", *name++);
ext3fs_dirhash(de->name, de->name_len, &h);
printk(":%x.%u ", h.hash,
((char *) de - base));
}
space += EXT3_DIR_REC_LEN(de->name_len);
names++;
}
de = ext3_next_entry(de);
}
printk("(%i)\n", names);
return (struct stats) { names, space, 1 };
}
struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir,
struct dx_entry *entries, int levels)
{
unsigned blocksize = dir->i_sb->s_blocksize;
unsigned count = dx_get_count (entries), names = 0, space = 0, i;
unsigned bcount = 0;
struct buffer_head *bh;
int err;
printk("%i indexed blocks...\n", count);
for (i = 0; i < count; i++, entries++)
{
u32 block = dx_get_block(entries), hash = i? dx_get_hash(entries): 0;
u32 range = i < count - 1? (dx_get_hash(entries + 1) - hash): ~hash;
struct stats stats;
printk("%s%3u:%03u hash %8x/%8x ",levels?"":" ", i, block, hash, range);
if (!(bh = ext3_bread (NULL,dir, block, 0,&err))) continue;
stats = levels?
dx_show_entries(hinfo, dir, ((struct dx_node *) bh->b_data)->entries, levels - 1):
dx_show_leaf(hinfo, (struct ext3_dir_entry_2 *) bh->b_data, blocksize, 0);
names += stats.names;
space += stats.space;
bcount += stats.bcount;
brelse (bh);
}
if (bcount)
printk("%snames %u, fullness %u (%u%%)\n", levels?"":" ",
names, space/bcount,(space/bcount)*100/blocksize);
return (struct stats) { names, space, bcount};
}
#endif /* DX_DEBUG */
/*
* Probe for a directory leaf block to search.
*
* dx_probe can return ERR_BAD_DX_DIR, which means there was a format
* error in the directory index, and the caller should fall back to
* searching the directory normally. The callers of dx_probe **MUST**
* check for this error code, and make sure it never gets reflected
* back to userspace.
*/
static struct dx_frame *
dx_probe(struct qstr *entry, struct inode *dir,
struct dx_hash_info *hinfo, struct dx_frame *frame_in, int *err)
{
unsigned count, indirect;
struct dx_entry *at, *entries, *p, *q, *m;
struct dx_root *root;
struct buffer_head *bh;
struct dx_frame *frame = frame_in;
u32 hash;
frame->bh = NULL;
if (!(bh = ext3_bread (NULL,dir, 0, 0, err)))
goto fail;
root = (struct dx_root *) bh->b_data;
if (root->info.hash_version != DX_HASH_TEA &&
root->info.hash_version != DX_HASH_HALF_MD4 &&
root->info.hash_version != DX_HASH_LEGACY) {
ext3_warning(dir->i_sb, __func__,
"Unrecognised inode hash code %d",
root->info.hash_version);
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail;
}
hinfo->hash_version = root->info.hash_version;
if (hinfo->hash_version <= DX_HASH_TEA)
hinfo->hash_version += EXT3_SB(dir->i_sb)->s_hash_unsigned;
hinfo->seed = EXT3_SB(dir->i_sb)->s_hash_seed;
if (entry)
ext3fs_dirhash(entry->name, entry->len, hinfo);
hash = hinfo->hash;
if (root->info.unused_flags & 1) {
ext3_warning(dir->i_sb, __func__,
"Unimplemented inode hash flags: %#06x",
root->info.unused_flags);
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail;
}
if ((indirect = root->info.indirect_levels) > 1) {
ext3_warning(dir->i_sb, __func__,
"Unimplemented inode hash depth: %#06x",
root->info.indirect_levels);
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail;
}
entries = (struct dx_entry *) (((char *)&root->info) +
root->info.info_length);
if (dx_get_limit(entries) != dx_root_limit(dir,
root->info.info_length)) {
ext3_warning(dir->i_sb, __func__,
"dx entry: limit != root limit");
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail;
}
dxtrace (printk("Look up %x", hash));
while (1)
{
count = dx_get_count(entries);
if (!count || count > dx_get_limit(entries)) {
ext3_warning(dir->i_sb, __func__,
"dx entry: no count or count > limit");
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail2;
}
p = entries + 1;
q = entries + count - 1;
while (p <= q)
{
m = p + (q - p)/2;
dxtrace(printk("."));
if (dx_get_hash(m) > hash)
q = m - 1;
else
p = m + 1;
}
if (0) // linear search cross check
{
unsigned n = count - 1;
at = entries;
while (n--)
{
dxtrace(printk(","));
if (dx_get_hash(++at) > hash)
{
at--;
break;
}
}
assert (at == p - 1);
}
at = p - 1;
dxtrace(printk(" %x->%u\n", at == entries? 0: dx_get_hash(at), dx_get_block(at)));
frame->bh = bh;
frame->entries = entries;
frame->at = at;
if (!indirect--) return frame;
if (!(bh = ext3_bread (NULL,dir, dx_get_block(at), 0, err)))
goto fail2;
at = entries = ((struct dx_node *) bh->b_data)->entries;
if (dx_get_limit(entries) != dx_node_limit (dir)) {
ext3_warning(dir->i_sb, __func__,
"dx entry: limit != node limit");
brelse(bh);
*err = ERR_BAD_DX_DIR;
goto fail2;
}
frame++;
frame->bh = NULL;
}
fail2:
while (frame >= frame_in) {
brelse(frame->bh);
frame--;
}
fail:
if (*err == ERR_BAD_DX_DIR)
ext3_warning(dir->i_sb, __func__,
"Corrupt dir inode %ld, running e2fsck is "
"recommended.", dir->i_ino);
return NULL;
}
static void dx_release (struct dx_frame *frames)
{
if (frames[0].bh == NULL)
return;
if (((struct dx_root *) frames[0].bh->b_data)->info.indirect_levels)
brelse(frames[1].bh);
brelse(frames[0].bh);
}
/*
* This function increments the frame pointer to search the next leaf
* block, and reads in the necessary intervening nodes if the search
* should be necessary. Whether or not the search is necessary is
* controlled by the hash parameter. If the hash value is even, then
* the search is only continued if the next block starts with that
* hash value. This is used if we are searching for a specific file.
*
* If the hash value is HASH_NB_ALWAYS, then always go to the next block.
*
* This function returns 1 if the caller should continue to search,
* or 0 if it should not. If there is an error reading one of the
* index blocks, it will a negative error code.
*
* If start_hash is non-null, it will be filled in with the starting
* hash of the next page.
*/
static int ext3_htree_next_block(struct inode *dir, __u32 hash,
struct dx_frame *frame,
struct dx_frame *frames,
__u32 *start_hash)
{
struct dx_frame *p;
struct buffer_head *bh;
int err, num_frames = 0;
__u32 bhash;
p = frame;
/*
* Find the next leaf page by incrementing the frame pointer.
* If we run out of entries in the interior node, loop around and
* increment pointer in the parent node. When we break out of
* this loop, num_frames indicates the number of interior
* nodes need to be read.
*/
while (1) {
if (++(p->at) < p->entries + dx_get_count(p->entries))
break;
if (p == frames)
return 0;
num_frames++;
p--;
}
/*
* If the hash is 1, then continue only if the next page has a
* continuation hash of any value. This is used for readdir
* handling. Otherwise, check to see if the hash matches the
* desired contiuation hash. If it doesn't, return since
* there's no point to read in the successive index pages.
*/
bhash = dx_get_hash(p->at);
if (start_hash)
*start_hash = bhash;
if ((hash & 1) == 0) {
if ((bhash & ~1) != hash)
return 0;
}
/*
* If the hash is HASH_NB_ALWAYS, we always go to the next
* block so no check is necessary
*/
while (num_frames--) {
if (!(bh = ext3_bread(NULL, dir, dx_get_block(p->at),
0, &err)))
return err; /* Failure */
p++;
brelse (p->bh);
p->bh = bh;
p->at = p->entries = ((struct dx_node *) bh->b_data)->entries;
}
return 1;
}
/*
* This function fills a red-black tree with information from a
* directory block. It returns the number directory entries loaded
* into the tree. If there is an error it is returned in err.
*/
static int htree_dirblock_to_tree(struct file *dir_file,
struct inode *dir, int block,
struct dx_hash_info *hinfo,
__u32 start_hash, __u32 start_minor_hash)
{
struct buffer_head *bh;
struct ext3_dir_entry_2 *de, *top;
int err, count = 0;
dxtrace(printk("In htree dirblock_to_tree: block %d\n", block));
if (!(bh = ext3_bread (NULL, dir, block, 0, &err)))
return err;
de = (struct ext3_dir_entry_2 *) bh->b_data;
top = (struct ext3_dir_entry_2 *) ((char *) de +
dir->i_sb->s_blocksize -
EXT3_DIR_REC_LEN(0));
for (; de < top; de = ext3_next_entry(de)) {
[PATCH] handle ext3 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 ext3 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 ext3_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 ext3_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 ext3. 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>
15 years ago
if (!ext3_check_dir_entry("htree_dirblock_to_tree", dir, de, bh,
(block<<EXT3_BLOCK_SIZE_BITS(dir->i_sb))
+((char *)de - bh->b_data))) {
/* On error, skip the f_pos to the next block. */
dir_file->f_pos = (dir_file->f_pos |
(dir->i_sb->s_blocksize - 1)) + 1;
brelse (bh);
return count;
}
ext3fs_dirhash(de->name, de->name_len, hinfo);
if ((hinfo->hash < start_hash) ||
((hinfo->hash == start_hash) &&
(hinfo->minor_hash < start_minor_hash)))
continue;
if (de->inode == 0)
continue;
if ((err = ext3_htree_store_dirent(dir_file,
hinfo->hash, hinfo->minor_hash, de)) != 0) {
brelse(bh);
return err;
}
count++;
}
brelse(bh);
return count;
}
/*
* This function fills a red-black tree with information from a
* directory. We start scanning the directory in hash order, starting
* at start_hash and start_minor_hash.
*
* This function returns the number of entries inserted into the tree,
* or a negative error code.
*/
int ext3_htree_fill_tree(struct file *dir_file, __u32 start_hash,
__u32 start_minor_hash, __u32 *next_hash)
{
struct dx_hash_info hinfo;
struct ext3_dir_entry_2 *de;
struct dx_frame frames[2], *frame;
struct inode *dir;
int block, err;
int count = 0;
int ret;
__u32 hashval;
dxtrace(printk("In htree_fill_tree, start hash: %x:%x\n", start_hash,
start_minor_hash));
dir = dir_file->f_path.dentry->d_inode;
if (!(EXT3_I(dir)->i_flags & EXT3_INDEX_FL)) {
hinfo.hash_version = EXT3_SB(dir->i_sb)->s_def_hash_version;
if (hinfo.hash_version <= DX_HASH_TEA)
hinfo.hash_version +=
EXT3_SB(dir->i_sb)->s_hash_unsigned;
hinfo.seed = EXT3_SB(dir->i_sb)->s_hash_seed;
count = htree_dirblock_to_tree(dir_file, dir, 0, &hinfo,
start_hash, start_minor_hash);
*next_hash = ~0;
return count;
}
hinfo.hash = start_hash;
hinfo.minor_hash = 0;
frame = dx_probe(NULL, dir_file->f_path.dentry->d_inode, &hinfo, frames, &err);
if (!frame)
return err;
/* Add '.' and '..' from the htree header */
if (!start_hash && !start_minor_hash) {
de = (struct ext3_dir_entry_2 *) frames[0].bh->b_data;
if ((err = ext3_htree_store_dirent(dir_file, 0, 0, de)) != 0)
goto errout;
count++;
}
if (start_hash < 2 || (start_hash ==2 && start_minor_hash==0)) {
de = (struct ext3_dir_entry_2 *) frames[0].bh->b_data;
de = ext3_next_entry(de);
if ((err = ext3_htree_store_dirent(dir_file, 2, 0, de)) != 0)
goto errout;
count++;
}
while (1) {
block = dx_get_block(frame->at);
ret = htree_dirblock_to_tree(dir_file, dir, block, &hinfo,
start_hash, start_minor_hash);
if (ret < 0) {
err = ret;
goto errout;
}
count += ret;
hashval = ~0;
ret = ext3_htree_next_block(dir, HASH_NB_ALWAYS,
frame, frames, &hashval);
*next_hash = hashval;
if (ret < 0) {
err = ret;
goto errout;
}
/*
* Stop if: (a) there are no more entries, or
* (b) we have inserted at least one entry and the
* next hash value is not a continuation
*/
if ((ret == 0) ||
(count && ((hashval & 1) == 0)))
break;
}
dx_release(frames);
dxtrace(printk("Fill tree: returned %d entries, next hash: %x\n",
count, *next_hash));
return count;
errout:
dx_release(frames);
return (err);
}
/*
* Directory block splitting, compacting
*/
ext34: ensure do_split leaves enough free space in both blocks The do_split() function for htree dir blocks is intended to split a leaf block to make room for a new entry. It sorts the entries in the original block by hash value, then moves the last half of the entries to the new block - without accounting for how much space this actually moves. (IOW, it moves half of the entry *count* not half of the entry *space*). If by chance we have both large & small entries, and we move only the smallest entries, and we have a large new entry to insert, we may not have created enough space for it. The patch below stores each record size when calculating the dx_map, and then walks the hash-sorted dx_map, calculating how many entries must be moved to more evenly split the existing entries between the old block and the new block, guaranteeing enough space for the new entry. The dx_map "offs" member is reduced to u16 so that the overall map size does not change - it is temporarily stored at the end of the new block, and if it grows too large it may be overwritten. By making offs and size both u16, we won't grow the map size. Also add a few comments to the functions involved. This fixes the testcase reported by hooanon05@yahoo.co.jp on the linux-ext4 list, "ext3 dir_index causes an error" Thanks to Andreas Dilger for discussing the problem & solution with me. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Tested-by: Junjiro Okajima <hooanon05@yahoo.co.jp> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <linux-ext4@vger.kernel.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
15 years ago
/*
* Create map of hash values, offsets, and sizes, stored at end of block.
* Returns number of entries mapped.
*/
static int dx_make_map(struct ext3_dir_entry_2 *de, unsigned blocksize,
struct dx_hash_info *hinfo, struct dx_map_entry *map_tail)
{
int count = 0;
char *base = (char *) de;
struct dx_hash_info h = *hinfo;
while ((char *) de < base + blocksize)
{
if (de->name_len && de->inode) {
ext3fs_dirhash(de->name, de->name_len, &h);
map_tail--;
map_tail->hash = h.hash;
ext34: ensure do_split leaves enough free space in both blocks The do_split() function for htree dir blocks is intended to split a leaf block to make room for a new entry. It sorts the entries in the original block by hash value, then moves the last half of the entries to the new block - without accounting for how much space this actually moves. (IOW, it moves half of the entry *count* not half of the entry *space*). If by chance we have both large & small entries, and we move only the smallest entries, and we have a large new entry to insert, we may not have created enough space for it. The patch below stores each record size when calculating the dx_map, and then walks the hash-sorted dx_map, calculating how many entries must be moved to more evenly split the existing entries between the old block and the new block, guaranteeing enough space for the new entry. The dx_map "offs" member is reduced to u16 so that the overall map size does not change - it is temporarily stored at the end of the new block, and if it grows too large it may be overwritten. By making offs and size both u16, we won't grow the map size. Also add a few comments to the functions involved. This fixes the testcase reported by hooanon05@yahoo.co.jp on the linux-ext4 list, "ext3 dir_index causes an error" Thanks to Andreas Dilger for discussing the problem & solution with me. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Tested-by: Junjiro Okajima <hooanon05@yahoo.co.jp> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <linux-ext4@vger.kernel.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
15 years ago
map_tail->offs = (u16) ((char *) de - base);
map_tail->size = le16_to_cpu(de->rec_len);
count++;
cond_resched();
}
/* XXX: do we need to check rec_len == 0 case? -Chris */
de = ext3_next_entry(de);
}
return count;
}
ext34: ensure do_split leaves enough free space in both blocks The do_split() function for htree dir blocks is intended to split a leaf block to make room for a new entry. It sorts the entries in the original block by hash value, then moves the last half of the entries to the new block - without accounting for how much space this actually moves. (IOW, it moves half of the entry *count* not half of the entry *space*). If by chance we have both large & small entries, and we move only the smallest entries, and we have a large new entry to insert, we may not have created enough space for it. The patch below stores each record size when calculating the dx_map, and then walks the hash-sorted dx_map, calculating how many entries must be moved to more evenly split the existing entries between the old block and the new block, guaranteeing enough space for the new entry. The dx_map "offs" member is reduced to u16 so that the overall map size does not change - it is temporarily stored at the end of the new block, and if it grows too large it may be overwritten. By making offs and size both u16, we won't grow the map size. Also add a few comments to the functions involved. This fixes the testcase reported by hooanon05@yahoo.co.jp on the linux-ext4 list, "ext3 dir_index causes an error" Thanks to Andreas Dilger for discussing the problem & solution with me. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Tested-by: Junjiro Okajima <hooanon05@yahoo.co.jp> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <linux-ext4@vger.kernel.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
15 years ago
/* Sort map by hash value */
static void dx_sort_map (struct dx_map_entry *map, unsigned count)
{
struct dx_map_entry *p, *q, *top = map + count - 1;
int more;
/* Combsort until bubble sort doesn't suck */
while (count > 2)
{
count = count*10/13;
if (count - 9 < 2) /* 9, 10 -> 11 */
count = 11;
for (p = top, q = p - count; q >= map; p--, q--)
if (p->hash < q->hash)
swap(*p, *q);
}
/* Garden variety bubble sort */
do {
more = 0;
q = top;
while (q-- > map)
{
if (q[1].hash >= q[0].hash)
continue;
swap(*(q+1), *q);
more = 1;
}
} while(more);
}
static void dx_insert_block(struct dx_frame *frame, u32 hash, u32 block)
{
struct dx_entry *entries = frame->entries;
struct dx_entry *old = frame->at, *new = old + 1;
int count = dx_get_count(entries);
assert(count < dx_get_limit(entries));
assert(old < entries + count);
memmove(new + 1, new, (char *)(entries + count) - (char *)(new));
dx_set_hash(new, hash);
dx_set_block(new, block);
dx_set_count(entries, count + 1);
}
static void ext3_update_dx_flag(struct inode *inode)
{
if (!EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
EXT3_FEATURE_COMPAT_DIR_INDEX))
EXT3_I(inode)->i_flags &= ~EXT3_INDEX_FL;
}
/*
* NOTE! unlike strncmp, ext3_match returns 1 for success, 0 for failure.
*
* `len <= EXT3_NAME_LEN' is guaranteed by caller.
* `de != NULL' is guaranteed by caller.
*/
static inline int ext3_match (int len, const char * const name,
struct ext3_dir_entry_2 * de)
{
if (len != de->name_len)
return 0;
if (!de->inode)
return 0;
return !memcmp(name, de->name, len);
}
/*
* Returns 0 if not found, -1 on failure, and 1 on success
*/
static inline int search_dirblock(struct buffer_head * bh,
struct inode *dir,
struct qstr *child,
unsigned long offset,
struct ext3_dir_entry_2 ** res_dir)
{
struct ext3_dir_entry_2 * de;
char * dlimit;
int de_len;
const char *name = child->name;
int namelen = child->len;
de = (struct ext3_dir_entry_2 *) bh->b_data;
dlimit = bh->b_data + dir->i_sb->s_blocksize;
while ((char *) de < dlimit) {
/* this code is executed quadratically often */
/* do minimal checking `by hand' */
if ((char *) de + namelen <= dlimit &&
ext3_match (namelen, name, de)) {
/* found a match - just to be sure, do a full check */
if (!ext3_check_dir_entry("ext3_find_entry",
dir, de, bh, offset))
return -1;
*res_dir = de;
return 1;
}
/* prevent looping on a bad block */
de_len = ext3_rec_len_from_disk(de->rec_len);
if (de_len <= 0)
return -1;
offset += de_len;
de = (struct ext3_dir_entry_2 *) ((char *) de + de_len);
}
return 0;
}
/*
* ext3_find_entry()
*
* finds an entry in the specified directory with the wanted name. It
* returns the cache buffer in which the entry was found, and the entry
* itself (as a parameter - res_dir). It does NOT read the inode of the
* entry - you'll have to do that yourself if you want to.
*
* The returned buffer_head has ->b_count elevated. The caller is expected
* to brelse() it when appropriate.
*/
static struct buffer_head *ext3_find_entry(struct inode *dir,
struct qstr *entry,
struct ext3_dir_entry_2 **res_dir)
{
struct super_block * sb;
struct buffer_head * bh_use[NAMEI_RA_SIZE];
struct buffer_head * bh, *ret = NULL;
unsigned long start, block, b;
const u8 *name = entry->name;
int ra_max = 0; /* Number of bh's in the readahead
buffer, bh_use[] */
int ra_ptr = 0; /* Current index into readahead
buffer */
int num = 0;
int nblocks, i, err;
int namelen;
*res_dir = NULL;
sb = dir->i_sb;
namelen = entry->len;
if (namelen > EXT3_NAME_LEN)
return NULL;
if ((namelen <= 2) && (name[0] == '.') &&
(name[1] == '.' || name[1] == 0)) {
/*
* "." or ".." will only be in the first block
* NFS may look up ".."; "." should be handled by the VFS
*/
block = start = 0;
nblocks = 1;
goto restart;
}