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namei.c
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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;
if ((bh = ext3_bread(handle, inode, *block, 1, err))) {
inode->i_size += inode->i_sb->s_blocksize;
EXT3_I(inode)->i_disksize = inode->i_size;
ext3_journal_get_write_access(handle,bh);
}
return bh;
}
#ifndef assert
#define assert(test) J_ASSERT(test)
#endif
#ifndef swap
#define swap(x, y) do { typeof(x) z = x; x = y; y = z; } while (0)
#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;
u32 offs;
};
#ifdef CONFIG_EXT3_INDEX
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 dentry *dentry,
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, int size,
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, int size);
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 dentry *dentry,
struct ext3_dir_entry_2 **res_dir, int *err);
static int ext3_dx_add_entry(handle_t *handle, struct dentry *dentry,
struct inode *inode);
/*
* 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 0? 20: 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 0? 22: 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 = (struct ext3_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
}
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 dentry *dentry, 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 (dentry)
dir = dentry->d_parent->d_inode;
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, __FUNCTION__,
"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;
hinfo->seed = EXT3_SB(dir->i_sb)->s_hash_seed;
if (dentry)
ext3fs_dirhash(dentry->d_name.name, dentry->d_name.len, hinfo);
hash = hinfo->hash;
if (root->info.unused_flags & 1) {
ext3_warning(dir->i_sb, __FUNCTION__,
"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, __FUNCTION__,
"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);
assert(dx_get_limit(entries) == dx_root_limit(dir,
root->info.info_length));
dxtrace (printk("Look up %x", hash));
while (1)
{
count = dx_get_count(entries);
assert (count && count <= dx_get_limit(entries));
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;
assert (dx_get_limit(entries) == dx_node_limit (dir));
frame++;
}
fail2:
while (frame >= frame_in) {
brelse(frame->bh);
frame--;
}
fail:
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;
}
/*
* 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 + le16_to_cpu(p->rec_len));
}
/*
* 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)) {
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;
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
*/
static int dx_make_map (struct ext3_dir_entry_2 *de, int size,
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 + size)
{
if (de->name_len && de->inode) {
ext3fs_dirhash(de->name, de->name_len, &h);
map_tail--;
map_tail->hash = h.hash;
map_tail->offs = (u32) ((char *) de - base);
count++;
cond_resched();
}
/* XXX: do we need to check rec_len == 0 case? -Chris */
de = (struct ext3_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
}
return count;
}
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);
}
#endif
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 dentry *dentry,
unsigned long offset,
struct ext3_dir_entry_2 ** res_dir)
{
struct ext3_dir_entry_2 * de;
char * dlimit;
int de_len;
const char *name = dentry->d_name.name;
int namelen = dentry->d_name.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 = le16_to_cpu(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 dentry *dentry,
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;
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;
struct inode *dir = dentry->d_parent->d_inode;
int namelen;
const u8 *name;
unsigned blocksize;
*res_dir = NULL;
sb = dir->i_sb;
blocksize = sb->s_blocksize;
namelen = dentry->d_name.len;
name = dentry->d_name.name;
if (namelen > EXT3_NAME_LEN)
return NULL;
#ifdef CONFIG_EXT3_INDEX
if (is_dx(dir)) {
bh = ext3_dx_find_entry(dentry, res_dir, &err);
/*
* On success, or if the error was file not found,
* return. Otherwise, fall back to doing a search the
* old fashioned way.
*/
if (bh || (err != ERR_BAD_DX_DIR))
return bh;
dxtrace(printk("ext3_find_entry: dx failed, falling back\n"));
}
#endif
nblocks = dir->i_size >> EXT3_BLOCK_SIZE_BITS(sb);
start = EXT3_I(dir)->i_dir_start_lookup;
if (start >= nblocks)
start = 0;
block = start;
restart:
do {
/*
* We deal with the read-ahead logic here.
*/
if (ra_ptr >= ra_max) {
/* Refill the readahead buffer */
ra_ptr = 0;
b = block;
for (ra_max = 0; ra_max < NAMEI_RA_SIZE; ra_max++) {
/*
* Terminate if we reach the end of the
* directory and must wrap, or if our
* search has finished at this block.
*/
if (b >= nblocks || (num && block == start)) {
bh_use[ra_max] = NULL;
break;
}
num++;
bh = ext3_getblk(NULL, dir, b++, 0, &err);
bh_use[ra_max] = bh;
if (bh)
ll_rw_block(READ_META, 1, &bh);
}
}
if ((bh = bh_use[ra_ptr++]) == NULL)
goto next;
wait_on_buffer(bh);
if (!buffer_uptodate(bh)) {
/* read error, skip block & hope for the best */
ext3_error(sb, __FUNCTION__, "reading directory #%lu "
"offset %lu", dir->i_ino, block);
brelse(bh);
goto next;
}
i = search_dirblock(bh, dir, dentry,
block << EXT3_BLOCK_SIZE_BITS(sb), res_dir);
if (i == 1) {
EXT3_I(dir)->i_dir_start_lookup = block;
ret = bh;
goto cleanup_and_exit;
} else {
brelse(bh);
if (i < 0)
goto cleanup_and_exit;
}
next:
if (++block >= nblocks)
block = 0;
} while (block != start);
/*
* If the directory has grown while we were searching, then
* search the last part of the directory before giving up.
*/
block = nblocks;
nblocks = dir->i_size >> EXT3_BLOCK_SIZE_BITS(sb);
if (block < nblocks) {
start = 0;
goto restart;
}
cleanup_and_exit:
/* Clean up the read-ahead blocks */
for (; ra_ptr < ra_max; ra_ptr++)
brelse (bh_use[ra_ptr]);
return ret;
}
#ifdef CONFIG_EXT3_INDEX
static struct buffer_head * ext3_dx_find_entry(struct dentry *dentry,
struct ext3_dir_entry_2 **res_dir, int *err)
{
struct super_block * sb;
struct dx_hash_info hinfo;
u32 hash;
struct dx_frame frames[2], *frame;
struct ext3_dir_entry_2 *de, *top;
struct buffer_head *bh;
unsigned long block;
int retval;
int namelen = dentry->d_name.len;
const u8 *name = dentry->d_name.name;
struct inode *dir = dentry->d_parent->d_inode;
sb = dir->i_sb;
/* NFS may look up ".." - look at dx_root directory block */
if (namelen > 2 || name[0] != '.'||(name[1] != '.' && name[1] != '\0')){
if (!(frame = dx_probe(dentry, NULL, &hinfo, frames, err)))
return NULL;
} else {
frame = frames;
frame->bh = NULL; /* for dx_release() */
frame->at = (struct dx_entry *)frames; /* hack for zero entry*/
dx_set_block(frame->at, 0); /* dx_root block is 0 */
}
hash = hinfo.hash;
do {
block = dx_get_block(frame->at);
if (!(bh = ext3_bread (NULL,dir, block, 0, err)))
goto errout;
de = (struct ext3_dir_entry_2 *) bh->b_data;
top = (struct ext3_dir_entry_2 *) ((char *) de + sb->s_blocksize -
EXT3_DIR_REC_LEN(0));
for (; de < top; de = ext3_next_entry(de))
if (ext3_match (namelen, name, de)) {
if (!ext3_check_dir_entry("ext3_find_entry",
dir, de, bh,
(block<<EXT3_BLOCK_SIZE_BITS(sb))
+((char *)de - bh->b_data))) {
brelse (bh);
*err = ERR_BAD_DX_DIR;
goto errout;
}
*res_dir = de;
dx_release (frames);
return bh;
}
brelse (bh);
/* Check to see if we should continue to search */
retval = ext3_htree_next_block(dir, hash, frame,
frames, NULL);
if (retval < 0) {
ext3_warning(sb, __FUNCTION__,
"error reading index page in directory #%lu",
dir->i_ino);
*err = retval;
goto errout;
}
} while (retval == 1);
*err = -ENOENT;
errout:
dxtrace(printk("%s not found\n", name));
dx_release (frames);
return NULL;
}
#endif
static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
{