From 7d7ca7c5269becab86c9f595309c8e90ce268967 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Fri, 28 Aug 2020 10:52:56 +0800 Subject: block: Add a new helper to attempt to merge a bio There are lots of duplicated code when trying to merge a bio from plug list and sw queue, we can introduce a new helper to attempt to merge a bio, which can simplify the blk_bio_list_merge() and blk_attempt_plug_merge(). Reviewed-by: Christoph Hellwig Signed-off-by: Baolin Wang Signed-off-by: Jens Axboe --- block/blk-merge.c | 104 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 53 insertions(+), 51 deletions(-) (limited to 'block/blk-merge.c') diff --git a/block/blk-merge.c b/block/blk-merge.c index b09e9fc44236..80c974484a3f 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -907,13 +907,14 @@ static void blk_account_io_merge_bio(struct request *req) part_stat_unlock(); } -bool bio_attempt_back_merge(struct request *req, struct bio *bio, - unsigned int nr_segs) +enum bio_merge_status bio_attempt_back_merge(struct request *req, + struct bio *bio, + unsigned int nr_segs) { const int ff = bio->bi_opf & REQ_FAILFAST_MASK; if (!ll_back_merge_fn(req, bio, nr_segs)) - return false; + return BIO_MERGE_FAILED; trace_block_bio_backmerge(req->q, req, bio); rq_qos_merge(req->q, req, bio); @@ -928,16 +929,17 @@ bool bio_attempt_back_merge(struct request *req, struct bio *bio, bio_crypt_free_ctx(bio); blk_account_io_merge_bio(req); - return true; + return BIO_MERGE_OK; } -bool bio_attempt_front_merge(struct request *req, struct bio *bio, - unsigned int nr_segs) +enum bio_merge_status bio_attempt_front_merge(struct request *req, + struct bio *bio, + unsigned int nr_segs) { const int ff = bio->bi_opf & REQ_FAILFAST_MASK; if (!ll_front_merge_fn(req, bio, nr_segs)) - return false; + return BIO_MERGE_FAILED; trace_block_bio_frontmerge(req->q, req, bio); rq_qos_merge(req->q, req, bio); @@ -954,11 +956,12 @@ bool bio_attempt_front_merge(struct request *req, struct bio *bio, bio_crypt_do_front_merge(req, bio); blk_account_io_merge_bio(req); - return true; + return BIO_MERGE_OK; } -bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, - struct bio *bio) +enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, + struct request *req, + struct bio *bio) { unsigned short segments = blk_rq_nr_discard_segments(req); @@ -976,10 +979,39 @@ bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, req->nr_phys_segments = segments + 1; blk_account_io_merge_bio(req); - return true; + return BIO_MERGE_OK; no_merge: req_set_nomerge(q, req); - return false; + return BIO_MERGE_FAILED; +} + +static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, + struct request *rq, + struct bio *bio, + unsigned int nr_segs, + bool sched_allow_merge) +{ + if (!blk_rq_merge_ok(rq, bio)) + return BIO_MERGE_NONE; + + switch (blk_try_merge(rq, bio)) { + case ELEVATOR_BACK_MERGE: + if (!sched_allow_merge || + (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio))) + return bio_attempt_back_merge(rq, bio, nr_segs); + break; + case ELEVATOR_FRONT_MERGE: + if (!sched_allow_merge || + (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio))) + return bio_attempt_front_merge(rq, bio, nr_segs); + break; + case ELEVATOR_DISCARD_MERGE: + return bio_attempt_discard_merge(q, rq, bio); + default: + return BIO_MERGE_NONE; + } + + return BIO_MERGE_FAILED; } /** @@ -1018,8 +1050,6 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, plug_list = &plug->mq_list; list_for_each_entry_reverse(rq, plug_list, queuelist) { - bool merged = false; - if (rq->q == q && same_queue_rq) { /* * Only blk-mq multiple hardware queues case checks the @@ -1029,24 +1059,11 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, *same_queue_rq = rq; } - if (rq->q != q || !blk_rq_merge_ok(rq, bio)) + if (rq->q != q) continue; - switch (blk_try_merge(rq, bio)) { - case ELEVATOR_BACK_MERGE: - merged = bio_attempt_back_merge(rq, bio, nr_segs); - break; - case ELEVATOR_FRONT_MERGE: - merged = bio_attempt_front_merge(rq, bio, nr_segs); - break; - case ELEVATOR_DISCARD_MERGE: - merged = bio_attempt_discard_merge(q, rq, bio); - break; - default: - break; - } - - if (merged) + if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == + BIO_MERGE_OK) return true; } @@ -1064,33 +1081,18 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, int checked = 8; list_for_each_entry_reverse(rq, list, queuelist) { - bool merged = false; - if (!checked--) break; - if (!blk_rq_merge_ok(rq, bio)) - continue; - - switch (blk_try_merge(rq, bio)) { - case ELEVATOR_BACK_MERGE: - if (blk_mq_sched_allow_merge(q, rq, bio)) - merged = bio_attempt_back_merge(rq, bio, - nr_segs); - break; - case ELEVATOR_FRONT_MERGE: - if (blk_mq_sched_allow_merge(q, rq, bio)) - merged = bio_attempt_front_merge(rq, bio, - nr_segs); - break; - case ELEVATOR_DISCARD_MERGE: - merged = bio_attempt_discard_merge(q, rq, bio); - break; - default: + switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { + case BIO_MERGE_NONE: continue; + case BIO_MERGE_OK: + return true; + case BIO_MERGE_FAILED: + return false; } - return merged; } return false; -- cgit v1.2.3