[PATCH 09/14] blk-mq-sched: cleanup blk_mq_sched_dispatch_requests()

[Ming Lei <ming.lei@redhat.com>]

This patch split blk_mq_sched_dispatch_requests()
into two parts:

1) the 1st part is for checking if queue is busy, and
handle the busy situation

2) the 2nd part is moved to __blk_mq_sched_dispatch_requests()
which focuses on dispatch from sw queue or scheduler queue.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq-sched.c | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index cc0687a4d0ab..07ff53187617 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -89,16 +89,37 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
 	return false;
 }
 
-void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+static void __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 {
 	struct request_queue *q = hctx->queue;
 	struct elevator_queue *e = q->elevator;
 	const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
-	bool can_go = true;
-	LIST_HEAD(rq_list);
 	struct request *(*dispatch_fn)(struct blk_mq_hw_ctx *) =
 		has_sched_dispatch ? e->type->ops.mq.dispatch_request :
 			blk_mq_dispatch_rq_from_ctxs;
+	LIST_HEAD(rq_list);
+
+	if (!has_sched_dispatch && !(hctx->flags & BLK_MQ_F_SHARED_DEPTH)) {
+		blk_mq_flush_busy_ctxs(hctx, &rq_list);
+		blk_mq_dispatch_rq_list(q, &rq_list);
+		return;
+	}
+
+	do {
+		struct request *rq;
+
+		rq = dispatch_fn(hctx);
+		if (!rq)
+			break;
+		list_add(&rq->queuelist, &rq_list);
+	} while (blk_mq_dispatch_rq_list(q, &rq_list));
+}
+
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+{
+	struct request_queue *q = hctx->queue;
+	bool can_go = true;
+	LIST_HEAD(rq_list);
 
 	/* RCU or SRCU read lock is needed before checking quiesced flag */
 	if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)))
@@ -144,25 +165,12 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 	if (!can_go || test_bit(BLK_MQ_S_BUSY, &hctx->state))
 		return;
 
-	if (!has_sched_dispatch && !(hctx->flags & BLK_MQ_F_SHARED_DEPTH)) {
-		blk_mq_flush_busy_ctxs(hctx, &rq_list);
-		blk_mq_dispatch_rq_list(q, &rq_list);
-		return;
-	}
-
 	/*
 	 * We want to dispatch from the scheduler if we had no work left
 	 * on the dispatch list, OR if we did have work but weren't able
 	 * to make progress.
 	 */
-	do {
-		struct request *rq;
-
-		rq = dispatch_fn(hctx);
-		if (!rq)
-			break;
-		list_add(&rq->queuelist, &rq_list);
-	} while (blk_mq_dispatch_rq_list(q, &rq_list));
+	__blk_mq_sched_dispatch_requests(hctx);
 }
 
 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
-- 
2.9.4