block: introduce bvec_nth_page()

Single-page bvec can often be seen in small BS workloads, so
introduce bvec_nth_page() for avoiding to call nth_page() unnecessarily,
which looks not cheap.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 066b66430523..c7e8a8273460 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -483,7 +483,7 @@ static unsigned blk_bvec_map_sg(struct request_queue *q,
 
                 offset = (total + bvec->bv_offset) % PAGE_SIZE;
                 idx = (total + bvec->bv_offset) / PAGE_SIZE;
-                pg = nth_page(bvec->bv_page, idx);
+                pg = bvec_nth_page(bvec->bv_page, idx);
 
                 sg_set_page(*sg, pg, seg_size, offset);