[PATCH 2/6] blk-mq: set data->ctx and data->hctx explicitly in blk_mq_get_request

[Ming Lei <ming.lei@xxxxxxxxxx>]

The only request allocation user which provides data->ctx and data->hctx
is blk_mq_alloc_request_hctx, now we have kill such use, so set
data->ctx and data->hctx explicitly in blk_mq_get_request()

Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/blk-mq.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e2e1b6808b32..35966af878c6 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -354,7 +354,6 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 	struct elevator_queue *e = q->elevator;
 	struct request *rq;
 	unsigned int tag;
-	bool clear_ctx_on_error = false;
 	u64 alloc_time_ns = 0;
 
 	blk_queue_enter_live(q);
@@ -364,13 +363,10 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 		alloc_time_ns = ktime_get_ns();
 
 	data->q = q;
-	if (likely(!data->ctx)) {
-		data->ctx = blk_mq_get_ctx(q);
-		clear_ctx_on_error = true;
-	}
-	if (likely(!data->hctx))
-		data->hctx = blk_mq_map_queue(q, data->cmd_flags,
-						data->ctx);
+
+	WARN_ON_ONCE(data->ctx || data->hctx);
+	data->ctx = blk_mq_get_ctx(q);
+	data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
 	if (data->cmd_flags & REQ_NOWAIT)
 		data->flags |= BLK_MQ_REQ_NOWAIT;
 
@@ -392,8 +388,8 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 
 	tag = blk_mq_get_tag(data);
 	if (tag == BLK_MQ_TAG_FAIL) {
-		if (clear_ctx_on_error)
-			data->ctx = NULL;
+		data->ctx = NULL;
+		data->hctx = NULL;
 		blk_queue_exit(q);
 		return NULL;
 	}
-- 
2.25.2