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blk-mq: simplify the plug handling in blk_mq_submit_bio

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blk_mq_submit_bio has two different plug cases, one that uses full
plugging and a limited plugging one.

The limited plugging case is only used for a corner case that does
not matter in real life:

 - no ->commit_rqs (so not NVMe)
 - no shared tags (so not SCSI)
 - not rotational (so no old disk or floppy driver)
 - must have multiple queues (so no eMMC)

Remove the limited merging case and all the related junk to simplify
blk_mq_submit_bio and the functions called from it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123160443.1315598-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2021-11-23 17:04:41 +01:00
committed by Jens Axboe
parent a4561f9fcc
commit 0c5bcc92d9
3 changed files with 15 additions and 64 deletions
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9
block/blk-merge.c
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@@ -1067,7 +1067,6 @@ static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
* @q: request_queue new bio is being queued at
* @bio: new bio being queued
* @nr_segs: number of segments in @bio
* @same_queue_rq: output value, will be true if there's an existing request
* from the passed in @q already in the plug list
*
* Determine whether @bio being queued on @q can be merged with the previous
@@ -1084,7 +1083,7 @@ static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,
* Caller must ensure !blk_queue_nomerges(q) beforehand.
*/
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs, bool *same_queue_rq)
unsigned int nr_segs)
{
struct blk_plug *plug;
struct request *rq;
@@ -1096,12 +1095,6 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
/* check the previously added entry for a quick merge attempt */
rq = rq_list_peek(&plug->mq_list);
if (rq->q == q) {
/*
* 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 = true;
if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) ==
BIO_MERGE_OK)
return true;