[PATCH 4/4] blk-mq: mark ctx as pending at batch in flush plug path

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

Most of times, flush plug should be the hottest I/O path,
so mark ctx as pending after all requests in the list are
inserted.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 block/blk-mq.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index deb5f4c..1c943b9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -993,18 +993,25 @@ void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 }
 EXPORT_SYMBOL(blk_mq_delay_queue);
 
-static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
-				    struct request *rq, bool at_head)
+static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
+					    struct blk_mq_ctx *ctx,
+					    struct request *rq,
+					    bool at_head)
 {
-	struct blk_mq_ctx *ctx = rq->mq_ctx;
-
 	trace_block_rq_insert(hctx->queue, rq);
 
 	if (at_head)
 		list_add(&rq->queuelist, &ctx->rq_list);
 	else
 		list_add_tail(&rq->queuelist, &ctx->rq_list);
+}
+
+static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
+				    struct request *rq, bool at_head)
+{
+	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
+	__blk_mq_insert_req_list(hctx, ctx, rq, at_head);
 	blk_mq_hctx_mark_pending(hctx, ctx);
 }
 
@@ -1060,8 +1067,9 @@ static void blk_mq_insert_requests(struct request_queue *q,
 		rq = list_first_entry(list, struct request, queuelist);
 		list_del_init(&rq->queuelist);
 		rq->mq_ctx = ctx;
-		__blk_mq_insert_request(hctx, rq, false);
+		__blk_mq_insert_req_list(hctx, ctx, rq, false);
 	}
+	blk_mq_hctx_mark_pending(hctx, ctx);
 	spin_unlock(&ctx->lock);
 
 	blk_mq_run_hw_queue(hctx, from_schedule);
-- 
1.9.1