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Btrfs: Write bio checksumming outside the FS mutex 

This significantly improves streaming write performance by allowing
concurrency in the data checksumming.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2008-04-16 11:15:20 -04:00
parent 44b8bd7edd
commit e015640f9c
3 changed files with 45 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/btrfs/ctree.h
View File

@ -1515,7 +1515,9 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
u64 bytenr, int mod);
int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct inode *inode,
struct bio *bio);
struct bio *bio, char *sums);
int btrfs_csum_one_bio(struct btrfs_root *root,
struct bio *bio, char **sums_ret);
struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,

46
fs/btrfs/file-item.c
View File

@ -134,9 +134,36 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
return ret;
}
int btrfs_csum_one_bio(struct btrfs_root *root,
struct bio *bio, char **sums_ret)
{
u32 *sums;
char *data;
struct bio_vec *bvec = bio->bi_io_vec;
int bio_index = 0;
sums = kmalloc(bio->bi_vcnt * BTRFS_CRC32_SIZE, GFP_NOFS);
if (!sums)
return -ENOMEM;
*sums_ret = (char *)sums;
while(bio_index < bio->bi_vcnt) {
data = kmap_atomic(bvec->bv_page, KM_USER0);
*sums = ~(u32)0;
*sums = btrfs_csum_data(root, data + bvec->bv_offset,
*sums, bvec->bv_len);
kunmap_atomic(data, KM_USER0);
btrfs_csum_final(*sums, (char *)sums);
sums++;
bio_index++;
bvec++;
}
return 0;
}
int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct inode *inode,
struct bio *bio)
struct bio *bio, char *sums)
{
u64 objectid = inode->i_ino;
u64 offset;
@ -150,12 +177,11 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
struct btrfs_csum_item *item_end;
struct extent_buffer *leaf = NULL;
u64 csum_offset;
u32 csum_result;
u32 *sums32 = (u32 *)sums;
u32 nritems;
u32 ins_size;
int bio_index = 0;
struct bio_vec *bvec = bio->bi_io_vec;
char *data;
char *eb_map;
char *eb_token;
unsigned long map_len;
@ -278,15 +304,6 @@ found:
btrfs_item_size_nr(leaf, path->slots[0]));
eb_token = NULL;
next_bvec:
data = kmap_atomic(bvec->bv_page, KM_USER0);
csum_result = ~(u32)0;
csum_result = btrfs_csum_data(root, data + bvec->bv_offset,
csum_result, bvec->bv_len);
kunmap_atomic(data, KM_USER0);
btrfs_csum_final(csum_result, (char *)&csum_result);
if (csum_result == 0) {
printk("csum result is 0 for inode %lu offset %Lu\n", inode->i_ino, offset);
}
if (!eb_token ||
(unsigned long)item + BTRFS_CRC32_SIZE >= map_start + map_len) {
@ -304,13 +321,14 @@ next_bvec:
}
if (eb_token) {
memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
&csum_result, BTRFS_CRC32_SIZE);
sums32, BTRFS_CRC32_SIZE);
} else {
write_extent_buffer(leaf, &csum_result, (unsigned long)item,
write_extent_buffer(leaf, sums32, (unsigned long)item,
BTRFS_CRC32_SIZE);
}
bio_index++;
bvec++;
sums32++;
if (bio_index < bio->bi_vcnt) {
item = (struct btrfs_csum_item *)((char *)item +
BTRFS_CRC32_SIZE);

11
fs/btrfs/inode.c
View File

@ -330,14 +330,23 @@ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_trans_handle *trans;
int ret = 0;
char *sums = NULL;
ret = btrfs_csum_one_bio(root, bio, &sums);
BUG_ON(ret);
mutex_lock(&root->fs_info->fs_mutex);
trans = btrfs_start_transaction(root, 1);
btrfs_set_trans_block_group(trans, inode);
btrfs_csum_file_blocks(trans, root, inode, bio);
btrfs_csum_file_blocks(trans, root, inode, bio, sums);
ret = btrfs_end_transaction(trans, root);
BUG_ON(ret);
mutex_unlock(&root->fs_info->fs_mutex);
kfree(sums);
return btrfs_map_bio(root, rw, bio, mirror_num);
}