diff options
Diffstat (limited to 'block/blk-merge.c')
| -rw-r--r-- | block/blk-merge.c | 36 |
1 files changed, 13 insertions, 23 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 14ce19607cd8..9b77b4d6c2a1 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -1084,8 +1084,8 @@ static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, * another request associated with @q is found on the plug list * (optional, may be %NULL) * - * Determine whether @bio being queued on @q can be merged with a request - * on %current's plugged list. Returns %true if merge was successful, + * Determine whether @bio being queued on @q can be merged with the previous + * request on %current's plugged list. Returns %true if merge was successful, * otherwise %false. * * Plugging coalesces IOs from the same issuer for the same purpose without @@ -1102,32 +1102,22 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, { struct blk_plug *plug; struct request *rq; - struct list_head *plug_list; plug = blk_mq_plug(q, bio); - if (!plug) + if (!plug || list_empty(&plug->mq_list)) return false; - plug_list = &plug->mq_list; - - list_for_each_entry_reverse(rq, plug_list, queuelist) { - if (rq->q == q && same_queue_rq) { - /* - * Only blk-mq multiple hardware queues case checks the - * rq in the same queue, there should be only one such - * rq in a queue - **/ - *same_queue_rq = rq; - } - - if (rq->q != q) - continue; - - if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == - BIO_MERGE_OK) - return true; + /* check the previously added entry for a quick merge attempt */ + rq = list_last_entry(&plug->mq_list, struct request, queuelist); + if (rq->q == q && same_queue_rq) { + /* + * Only blk-mq multiple hardware queues case checks the rq in + * the same queue, there should be only one such rq in a queue + */ + *same_queue_rq = rq; } - + if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == BIO_MERGE_OK) + return true; return false; } |