linux-hardened/fs/ext3/dir.c
Eric Sandeen a4ae309486 ext3: speed up file creates by optimizing rec_len functions
The addition of 64k block capability in the rec_len_from_disk
and rec_len_to_disk functions added a bit of math overhead which
slows down file create workloads needlessly when the architecture
cannot even support 64k blocks, thanks to page size limits.

Similar changes already exist in the ext4 codebase.

The directory entry checking can also be optimized a bit
by sprinkling in some unlikely() conditions to move the
error handling out of line.

bonnie++ sequential file creates on a 512MB ramdisk speeds up
from about 77,000/s to about 82,000/s, about a 6% improvement.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2011-01-10 19:04:07 +01:00

519 lines
14 KiB
C

/*
* 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/fs.h>
#include <linux/jbd.h>
#include <linux/ext3_fs.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/rbtree.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_readdir(struct file *, void *, filldir_t);
static int ext3_dx_readdir(struct file * filp,
void * dirent, filldir_t filldir);
static int ext3_release_dir (struct inode * inode,
struct file * filp);
const struct file_operations ext3_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = ext3_readdir, /* we take BKL. needed?*/
.unlocked_ioctl = ext3_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext3_compat_ioctl,
#endif
.fsync = ext3_sync_file, /* BKL held */
.release = ext3_release_dir,
};
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]);
}
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 * filp,
void * dirent, filldir_t filldir)
{
int error = 0;
unsigned long offset;
int i, stored;
struct ext3_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 (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))) {
err = ext3_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.
*/
EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_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 >> 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(&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 = 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, 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 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;
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 ext3_dir_entry_2 *) (bh->b_data + offset);
if (!ext3_check_dir_entry ("ext3_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 += ext3_rec_len_from_disk(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 += ext3_rec_len_from_disk(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_ROOT;
else if (parent->rb_left == n)
parent->rb_left = NULL;
else if (parent->rb_right == n)
parent->rb_right = NULL;
n = parent;
}
}
static struct dir_private_info *ext3_htree_create_dir_info(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(pos);
p->curr_minor_hash = pos2min_hash(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 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;
return error;
}
fname = fname->next;
}
return 0;
}
static int ext3_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 = ext3_htree_create_dir_info(filp->f_pos);
if (!info)
return -ENOMEM;
filp->private_data = info;
}
if (filp->f_pos == EXT3_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) {
if (call_filldir(filp, dirent, filldir, 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) ||
(filp->f_version != inode->i_version)) {
info->curr_node = NULL;
free_rb_tree_fname(&info->root);
filp->f_version = inode->i_version;
ret = ext3_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 = EXT3_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;
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) {
filp->f_pos = EXT3_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 ext3_release_dir (struct inode * inode, struct file * filp)
{
if (filp->private_data)
ext3_htree_free_dir_info(filp->private_data);
return 0;
}