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 <hch@lst.de>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b09e9fc..80c9744 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))
+ switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) {
+ case BIO_MERGE_NONE:
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:
- continue;
+ case BIO_MERGE_OK:
+ return true;
+ case BIO_MERGE_FAILED:
+ return false;
}
- return merged;
}
return false;
