Commit 9699d4f9 authored by Tahsin Erdogan's avatar Tahsin Erdogan Committed by Theodore Ts'o

ext4: make xattr inode reads faster

ext4_xattr_inode_read() currently reads each block sequentially while
waiting for io operation to complete before moving on to the next
block. This prevents request merging in block layer.

Add a ext4_bread_batch() function that starts reads for all blocks
then optionally waits for them to complete. A similar logic is used
in ext4_find_entry(), so update that code to use the new function.
Signed-off-by: default avatarTahsin Erdogan <tahsin@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent ec000220
......@@ -2461,6 +2461,8 @@ extern void ext4_process_freed_data(struct super_block *sb, tid_t commit_tid);
int ext4_inode_is_fast_symlink(struct inode *inode);
struct buffer_head *ext4_getblk(handle_t *, struct inode *, ext4_lblk_t, int);
struct buffer_head *ext4_bread(handle_t *, struct inode *, ext4_lblk_t, int);
int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
bool wait, struct buffer_head **bhs);
int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create);
int ext4_get_block(struct inode *inode, sector_t iblock,
......
......@@ -1015,6 +1015,50 @@ struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
return ERR_PTR(-EIO);
}
/* Read a contiguous batch of blocks. */
int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
bool wait, struct buffer_head **bhs)
{
int i, err;
for (i = 0; i < bh_count; i++) {
bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
if (IS_ERR(bhs[i])) {
err = PTR_ERR(bhs[i]);
bh_count = i;
goto out_brelse;
}
}
for (i = 0; i < bh_count; i++)
/* Note that NULL bhs[i] is valid because of holes. */
if (bhs[i] && !buffer_uptodate(bhs[i]))
ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1,
&bhs[i]);
if (!wait)
return 0;
for (i = 0; i < bh_count; i++)
if (bhs[i])
wait_on_buffer(bhs[i]);
for (i = 0; i < bh_count; i++) {
if (bhs[i] && !buffer_uptodate(bhs[i])) {
err = -EIO;
goto out_brelse;
}
}
return 0;
out_brelse:
for (i = 0; i < bh_count; i++) {
brelse(bhs[i]);
bhs[i] = NULL;
}
return err;
}
int ext4_walk_page_buffers(handle_t *handle,
struct buffer_head *head,
unsigned from,
......
......@@ -1342,13 +1342,12 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
struct super_block *sb;
struct buffer_head *bh_use[NAMEI_RA_SIZE];
struct buffer_head *bh, *ret = NULL;
ext4_lblk_t start, block, b;
ext4_lblk_t start, block;
const u8 *name = d_name->name;
int ra_max = 0; /* Number of bh's in the readahead
size_t ra_max = 0; /* Number of bh's in the readahead
buffer, bh_use[] */
int ra_ptr = 0; /* Current index into readahead
size_t ra_ptr = 0; /* Current index into readahead
buffer */
int num = 0;
ext4_lblk_t nblocks;
int i, namelen, retval;
struct ext4_filename fname;
......@@ -1411,31 +1410,17 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
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 = ext4_getblk(NULL, dir, b++, 0);
if (IS_ERR(bh)) {
if (ra_max == 0) {
ret = bh;
goto cleanup_and_exit;
}
break;
}
bh_use[ra_max] = bh;
if (bh)
ll_rw_block(REQ_OP_READ,
REQ_META | REQ_PRIO,
1, &bh);
if (block < start)
ra_max = start - block;
else
ra_max = nblocks - block;
ra_max = min(ra_max, ARRAY_SIZE(bh_use));
retval = ext4_bread_batch(dir, block, ra_max,
false /* wait */, bh_use);
if (retval) {
ret = ERR_PTR(retval);
ra_max = 0;
goto cleanup_and_exit;
}
}
if ((bh = bh_use[ra_ptr++]) == NULL)
......
......@@ -317,28 +317,41 @@ static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
*/
static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
{
unsigned long block = 0;
struct buffer_head *bh;
int blocksize = ea_inode->i_sb->s_blocksize;
size_t csize, copied = 0;
void *copy_pos = buf;
while (copied < size) {
csize = (size - copied) > blocksize ? blocksize : size - copied;
bh = ext4_bread(NULL, ea_inode, block, 0);
if (IS_ERR(bh))
return PTR_ERR(bh);
if (!bh)
return -EFSCORRUPTED;
int blocksize = 1 << ea_inode->i_blkbits;
int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
int tail_size = (size % blocksize) ?: blocksize;
struct buffer_head *bhs_inline[8];
struct buffer_head **bhs = bhs_inline;
int i, ret;
if (bh_count > ARRAY_SIZE(bhs_inline)) {
bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
if (!bhs)
return -ENOMEM;
}
memcpy(copy_pos, bh->b_data, csize);
brelse(bh);
ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
true /* wait */, bhs);
if (ret)
goto free_bhs;
copy_pos += csize;
block += 1;
copied += csize;
for (i = 0; i < bh_count; i++) {
/* There shouldn't be any holes in ea_inode. */
if (!bhs[i]) {
ret = -EFSCORRUPTED;
goto put_bhs;
}
memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
i < bh_count - 1 ? blocksize : tail_size);
}
return 0;
ret = 0;
put_bhs:
for (i = 0; i < bh_count; i++)
brelse(bhs[i]);
free_bhs:
if (bhs != bhs_inline)
kfree(bhs);
return ret;
}
static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
......
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