[PATCH v2 23/51] blk-merge: compute bio->bi_seg_front_size efficiently
STALE3381d
From: Ming Lei <hidden>
Date: 2017-06-26 12:10:06
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Revision v2 of 7 in this series.
Revisions (7)
It is enough to check and compute bio->bi_seg_front_size just after the 1st segment is found, but current code checks that for each bvec, which is inefficient. This patch follows the way in __blk_recalc_rq_segments() for computing bio->bi_seg_front_size, and it is more efficient and code becomes more readable too. Signed-off-by: Ming Lei <redacted> --- block/blk-merge.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 5df13041b851..821b9c206308 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c@@ -145,22 +145,21 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bvprvp = &bvprv; sectors += bv.bv_len >> 9; - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; continue; } new_segment: if (nsegs == queue_max_segments(q)) goto split; + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; + nsegs++; bvprv = bv; bvprvp = &bvprv; seg_size = bv.bv_len; sectors += bv.bv_len >> 9; - if (nsegs == 1 && seg_size > front_seg_size) - front_seg_size = seg_size; } do_split = false;
@@ -173,6 +172,8 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bio = new; } + if (nsegs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; bio->bi_seg_front_size = front_seg_size; if (seg_size > bio->bi_seg_back_size) bio->bi_seg_back_size = seg_size;
--
2.9.4