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blk-mq: split the plug and sync cases in blk_mq_make_request

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Now that we have a nice direct issue heper this helps simplifying
the code a bit, and also gets rid of the old_rq variable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2017-03-22 15:01:52 -04:00 committed by Jens Axboe
parent 5eb6126e1c
commit 2299722c4b
1 changed files with 18 additions and 18 deletions
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36
block/blk-mq.c
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@ -1569,32 +1569,32 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
list_add_tail(&rq->queuelist, &plug->mq_list); list_add_tail(&rq->queuelist, &plug->mq_list);
goto done; goto done;
} else if (((plug && !blk_queue_nomerges(q)) || is_sync)) { } else if (plug && !blk_queue_nomerges(q)) {
struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio); blk_mq_bio_to_request(rq, bio);
/* /*
* We do limited plugging. If the bio can be merged, do that. * We do limited plugging. If the bio can be merged, do that.
* Otherwise the existing request in the plug list will be * Otherwise the existing request in the plug list will be
* issued. So the plug list will have one request at most * issued. So the plug list will have one request at most
* The plug list might get flushed before this. If that happens,
* the plug list is empty, and same_queue_rq is invalid.
*/ */
if (plug) { if (list_empty(&plug->mq_list))
/* same_queue_rq = NULL;
* The plug list might get flushed before this. If that if (same_queue_rq)
* happens, same_queue_rq is invalid and plug list is list_del_init(&same_queue_rq->queuelist);
* empty list_add_tail(&rq->queuelist, &plug->mq_list);
*/
if (same_queue_rq && !list_empty(&plug->mq_list)) {
old_rq = same_queue_rq;
list_del_init(&old_rq->queuelist);
}
list_add_tail(&rq->queuelist, &plug->mq_list);
} else /* is_sync */
old_rq = rq;
blk_mq_put_ctx(data.ctx); blk_mq_put_ctx(data.ctx);
if (old_rq) if (same_queue_rq)
blk_mq_try_issue_directly(data.hctx, old_rq, &cookie); blk_mq_try_issue_directly(data.hctx, same_queue_rq,
&cookie);
goto done;
} else if (is_sync) {
blk_mq_bio_to_request(rq, bio);
blk_mq_put_ctx(data.ctx);
blk_mq_try_issue_directly(data.hctx, rq, &cookie);
goto done; goto done;
} }