block: factor out blk_mq_dispatch_queue_requests() helper

Factor out the logic from blk_mq_flush_plug_list() that calls
->queue_rqs() with a fallback to ->queue_rq() into a helper function
blk_mq_dispatch_queue_requests(). This is in preparation for using this
code with other lists of requests.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250426011728.4189119-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 22 insertions, 21 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index fb514fd41d76..a777cb361ee3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2836,6 +2836,27 @@ static void __blk_mq_flush_list(struct request_queue *q, struct rq_list *rqs)
 	q->mq_ops->queue_rqs(rqs);
 }
 
+static void blk_mq_dispatch_queue_requests(struct rq_list *rqs, unsigned depth)
+{
+	struct request_queue *q = rq_list_peek(rqs)->q;
+
+	trace_block_unplug(q, depth, true);
+
+	/*
+	 * Peek first request and see if we have a ->queue_rqs() hook.
+	 * If we do, we can dispatch the whole list in one go.
+	 * We already know at this point that all requests belong to the
+	 * same queue, caller must ensure that's the case.
+	 */
+	if (q->mq_ops->queue_rqs) {
+		blk_mq_run_dispatch_ops(q, __blk_mq_flush_list(q, rqs));
+		if (rq_list_empty(rqs))
+			return;
+	}
+
+	blk_mq_run_dispatch_ops(q, blk_mq_issue_direct(rqs));
+}
+
 static void blk_mq_dispatch_list(struct rq_list *rqs, bool from_sched)
 {
 	struct blk_mq_hw_ctx *this_hctx = NULL;
@@ -2883,7 +2904,6 @@ static void blk_mq_dispatch_list(struct rq_list *rqs, bool from_sched)
 
 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 {
-	struct request *rq;
 	unsigned int depth;
 
 	/*
@@ -2899,26 +2919,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 	plug->rq_count = 0;
 
 	if (!plug->multiple_queues && !plug->has_elevator && !from_schedule) {
-		struct request_queue *q;
-
-		rq = rq_list_peek(&plug->mq_list);
-		q = rq->q;
-		trace_block_unplug(q, depth, true);
-
-		/*
-		 * Peek first request and see if we have a ->queue_rqs() hook.
-		 * If we do, we can dispatch the whole plug list in one go. We
-		 * already know at this point that all requests belong to the
-		 * same queue, caller must ensure that's the case.
-		 */
-		if (q->mq_ops->queue_rqs) {
-			blk_mq_run_dispatch_ops(q,
-				__blk_mq_flush_list(q, &plug->mq_list));
-			if (rq_list_empty(&plug->mq_list))
-				return;
-		}
-
-		blk_mq_run_dispatch_ops(q, blk_mq_issue_direct(&plug->mq_list));
+		blk_mq_dispatch_queue_requests(&plug->mq_list, depth);
 		if (rq_list_empty(&plug->mq_list))
 			return;
 	}