blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()

If we have scheduling enabled, we jump directly to insert-and-run.=0A= 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=0A= cases.=0A=

Quoted 4 lines · Jens Axboe

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.

How about renaming "can_block" into "may_sleep"? Otherwise this patch looks fine to me.

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.

Signed-off-by Jens Axboe <[email protected]>

block/blk-mq.c +5 -4

index 159187a28d66..4196d6bee92d 100644
@@ -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;

Signature · 2 lines

-- 
Jens Axboe

Quoted 4 lines · Jens Axboe

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 <[email protected]>

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.