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authorMing Lei <ming.lei@redhat.com>2019-02-27 20:40:11 +0800
committerJens Axboe <axboe@kernel.dk>2019-02-27 06:18:54 -0700
commit48d7727cae1209235700ed90f8f11426027b333b (patch)
treeb4232539d43b720be2c0ff40017c14457000e0e2 /block
parent4d633062c1c0794a6b3836b7b55afba4599736e8 (diff)
downloadlinux-stericsson-48d7727cae1209235700ed90f8f11426027b333b.tar.gz
block: optimize __blk_segment_map_sg() for single-page bvec
Introduce a fast path for single-page bvec IO, then blk_bvec_map_sg() can be avoided. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-merge.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index c7e8a8273460..c1ad8abbd9d6 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -447,7 +447,7 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
return biovec_phys_mergeable(q, &end_bv, &nxt_bv);
}
-static struct scatterlist *blk_next_sg(struct scatterlist **sg,
+static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
struct scatterlist *sglist)
{
if (!*sg)
@@ -512,7 +512,12 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
(*sg)->length += nbytes;
} else {
new_segment:
- (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg);
+ if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) {
+ *sg = blk_next_sg(sg, sglist);
+ sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
+ (*nsegs) += 1;
+ } else
+ (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg);
}
*bvprv = *bvec;
}