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>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 374d024..9259aec 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -134,9 +134,36 @@
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 @@
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 @@
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 @@
}
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);