Btrfs: load checksum data once when submitting a direct read io
The current code would load checksum data for several times when we split
a whole direct read io because of the limit of the raid stripe, it would
make us search the csum tree for several times. In fact, it just wasted time,
and made the contention of the csum tree root be more serious. This patch
improves this problem by loading the data at once.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d5e71d4..d2f8f39 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2621,9 +2621,18 @@
struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
{
- return bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
-}
+ struct btrfs_io_bio *btrfs_bio;
+ struct bio *new;
+ new = bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
+ if (new) {
+ btrfs_bio = btrfs_io_bio(new);
+ btrfs_bio->csum = NULL;
+ btrfs_bio->csum_allocated = NULL;
+ btrfs_bio->end_io = NULL;
+ }
+ return new;
+}
/* this also allocates from the btrfs_bioset */
struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)