linux-kernel - [PATCH V2 3/5] blk-mq: move actual issue into one helper

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Date:   Mon, 27 Nov 2017 13:07:19 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jens Axboe <axboe@...com>, linux-block@...r.kernel.org,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com
Cc:     Christoph Hellwig <hch@...radead.org>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        linux-kernel@...r.kernel.org, Hannes Reinecke <hare@...e.com>,
        Omar Sandoval <osandov@...com>, Ming Lei <ming.lei@...hat.com>
Subject: [PATCH V2 3/5] blk-mq: move actual issue into one helper

No functional change, just to clean up code a bit, so that the following
change of using direct issue for blk_mq_request_bypass_insert() which is
needed by DM can be easier to do.

Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
 block/blk-mq.c | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 11097477eeab..fe82d7a47b35 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1593,15 +1593,38 @@ 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 blk_mq_hw_ctx *hctx,
-					struct request *rq,
-					blk_qc_t *cookie, bool may_sleep)
+/* return true if insert is needed */
+static bool __blk_mq_issue_req(struct blk_mq_hw_ctx *hctx,
+			       struct request *rq,
+			       blk_qc_t *new_cookie,
+			       blk_status_t *ret)
 {
 	struct request_queue *q = rq->q;
 	struct blk_mq_queue_data bd = {
 		.rq = rq,
 		.last = true,
 	};
+
+	if (!blk_mq_get_driver_tag(rq, NULL, false))
+		return true;
+
+	if (!blk_mq_get_dispatch_budget(hctx)) {
+		blk_mq_put_driver_tag(rq);
+		return true;
+	}
+
+	*new_cookie = request_to_qc_t(hctx, rq);
+
+	*ret = q->mq_ops->queue_rq(hctx, &bd);
+
+	return false;
+}
+
+static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+					struct request *rq,
+					blk_qc_t *cookie, bool may_sleep)
+{
+	struct request_queue *q = rq->q;
 	blk_qc_t new_cookie;
 	blk_status_t ret;
 	bool run_queue = true;
@@ -1615,22 +1638,14 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 	if (q->elevator)
 		goto insert;
 
-	if (!blk_mq_get_driver_tag(rq, NULL, false))
+	if (__blk_mq_issue_req(hctx, rq, &new_cookie, &ret))
 		goto insert;
 
-	if (!blk_mq_get_dispatch_budget(hctx)) {
-		blk_mq_put_driver_tag(rq);
-		goto insert;
-	}
-
-	new_cookie = request_to_qc_t(hctx, rq);
-
 	/*
 	 * For OK queue, we are done. For error, kill it. Any other
 	 * error (busy), just add it to our list as we previously
 	 * would have done
 	 */
-	ret = q->mq_ops->queue_rq(hctx, &bd);
 	switch (ret) {
 	case BLK_STS_OK:
 		*cookie = new_cookie;
-- 
2.9.5