From: Ming Lei <ming.lei@canonical.com>
Date: Tue, 20 Oct 2015 15:13:54 +0000 (+0800)
Subject: blk-mq: check bio_mergeable() early before merging
X-Git-Tag: v4.4-rc1~134^2~5
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;ds=sidebyside;h=e18378a60e27ad7b3e11ecc4e2c92159585dee68;p=cascardo%2Flinux.git

blk-mq: check bio_mergeable() early before merging

It isn't necessary to try to merge the bio which is marked
as NOMERGE.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9683a561efcd..d38371160019 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1140,7 +1140,7 @@ static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
 					 struct blk_mq_ctx *ctx,
 					 struct request *rq, struct bio *bio)
 {
-	if (!hctx_allow_merges(hctx)) {
+	if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
 		blk_mq_bio_to_request(rq, bio);
 		spin_lock(&ctx->lock);
 insert_rq: