Re: [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
From: Omar Sandoval <osandov@osandov.com>
Date: 2017-03-14 17:49:25
On Tue, Mar 14, 2017 at 08:57:50AM -0600, Jens Axboe wrote:
If we have scheduling enabled, we jump directly to insert-and-run. That's fine, but we run the queue async and we don't pass in information on whether we can block from this context or not. Fixup both these cases.
Reviewed-by: Omar Sandoval <redacted> Just one question: we call blk_mq_get_driver_tag() with wait=false in blk_mq_try_issue_directly(). Should we change that to wait=can_block? Maybe it's pointless to try a direct issue if we'd have to wait for a tag anyways, though.
quoted hunk ↗ jump to hunk
Signed-off-by: Jens Axboe <axboe@fb.com>diff --git a/block/blk-mq.c b/block/blk-mq.c index 159187a28d66..4196d6bee92d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c@@ -1434,7 +1434,8 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq) return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true); } -static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie) +static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie, + bool can_block) { struct request_queue *q = rq->q; struct blk_mq_queue_data bd = {@@ -1475,7 +1476,7 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie) } insert: - blk_mq_sched_insert_request(rq, false, true, true, false); + blk_mq_sched_insert_request(rq, false, true, false, can_block); } /*@@ -1569,11 +1570,11 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) { rcu_read_lock(); - blk_mq_try_issue_directly(old_rq, &cookie); + blk_mq_try_issue_directly(old_rq, &cookie, false); rcu_read_unlock(); } else { srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu); - blk_mq_try_issue_directly(old_rq, &cookie); + blk_mq_try_issue_directly(old_rq, &cookie, true); srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx); } goto done;-- Jens Axboe