blk-mq: only try to run plug merge if request has same queue with incoming bio

It is obvious that io merge can't be done between two different queues, so
just try to run io merge in case of same queue.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211102133502.3619184-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-merge.c b/block/blk-merge.c
index df69f4bb771724a86ed59315ac12ab4b42b449e5..893c1a60b701f19eb2f565b8133fa3a4bb96f017 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -1101,9 +1101,11 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
                 * the same queue, there should be only one such rq in a queue
                 */
                *same_queue_rq = true;
+
+               if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) ==
+                               BIO_MERGE_OK)
+                       return true;
        }
-       if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == BIO_MERGE_OK)
-               return true;
        return false;
 }