blk-mq: Simplify request completion state

There are no more users relying on blk-mq request states to prevent
double completions, so replace the relatively expensive cmpxchg operation
with WRITE_ONCE.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7c8cfa0..cda6988 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -568,9 +568,7 @@ static void __blk_mq_complete_request(struct request *rq)
        bool shared = false;
        int cpu;
 
-       if (!blk_mq_mark_complete(rq))
-               return;
-
+       WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
        /*
         * Most of single queue controllers, there is only one irq vector
         * for handling IO completion, and the only irq's affinity is set

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 6e3da35..b8de11e 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -329,20 +329,6 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q);
 
 unsigned int blk_mq_rq_cpu(struct request *rq);
 
-/**
- * blk_mq_mark_complete() - Set request state to complete
- * @rq: request to set to complete state
- *
- * Returns true if request state was successfully set to complete. If
- * successful, the caller is responsibile for seeing this request is ended, as
- * blk_mq_complete_request will not work again.
- */
-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.