[1/2] blk-mq: export setting request completion state

Commit Message

Keith Busch July 19, 2018, 9:26 p.m. UTC

This is preparing for drivers that want to directly alter the state of
their requests. No functional change here.

Signed-off-by: Keith Busch <[e-mail]>
---
 block/blk-mq.c         | 4 +---
 include/linux/blk-mq.h | 9 +++++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

Comments

Christoph Hellwig July 23, 2018, 8:09 a.m. UTC | #1

> +/*
> + * Returns true if request was not in flight.
> + */
> +static inline bool blk_mq_mark_complete(struct request *rq)
> +{
> +	return (cmpxchg(&rq->state, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE) !=
> +			MQ_RQ_IN_FLIGHT);
> +}

This needs a much better comment describing when and how to use it.

Also the outer braces in the return statement are not required.

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 22326612a5d3..f50559718b71 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -558,10 +558,8 @@  static void __blk_mq_complete_request(struct request *rq)
 	bool shared = false;
 	int cpu;
 
-	if (cmpxchg(&rq->state, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE) !=
-			MQ_RQ_IN_FLIGHT)
+	if (blk_mq_mark_complete(rq))
 		return;
-
 	if (rq->internal_tag != -1)
 		blk_mq_sched_completed_request(rq);
 
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 9b0fd11ce89a..0ae115e95476 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -289,6 +289,15 @@  void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);
 
 void blk_mq_quiesce_queue_nowait(struct request_queue *q);
 
+/*
+ * Returns true if request was not in flight.
+ */
+static inline bool blk_mq_mark_complete(struct request *rq)
+{
+	return (cmpxchg(&rq->state, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE) !=
+			MQ_RQ_IN_FLIGHT);
+}
+
 /*
  * Driver command data is immediately after the request. So subtract request
  * size to get back to the original request, add request size to get the PDU.