blk-mq: unify hctx delayed_run_work and run_work

They serve the exact same purpose. Get rid of the non-delayed
work variant, and just run it without delay for the normal case.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-core.c

@@ -269,7 +269,7 @@ void blk_sync_queue(struct request_queue *q)
 		int i;
 
 		queue_for_each_hw_ctx(q, hctx, i) {
-			cancel_work_sync(&hctx->run_work);
+			cancel_delayed_work_sync(&hctx->run_work);
 			cancel_delayed_work_sync(&hctx->delay_work);
 		}
 	} else {

block/blk-mq.c

@@ -1166,12 +1166,8 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
 		put_cpu();
 	}
 
-	if (msecs == 0)
-		kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx),
-					 &hctx->run_work);
-	else
 	kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
-						 &hctx->delayed_run_work,
+					 &hctx->run_work,
 					 msecs_to_jiffies(msecs));
 }
 
@@ -1224,7 +1220,7 @@ EXPORT_SYMBOL(blk_mq_queue_stopped);
 
 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
-	cancel_work(&hctx->run_work);
+	cancel_delayed_work_sync(&hctx->run_work);
 	cancel_delayed_work(&hctx->delay_work);
 	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 }
@@ -1282,17 +1278,7 @@ static void blk_mq_run_work_fn(struct work_struct *work)
 {
 	struct blk_mq_hw_ctx *hctx;
 
-	hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
-
-	__blk_mq_run_hw_queue(hctx);
-}
-
-static void blk_mq_delayed_run_work_fn(struct work_struct *work)
-{
-	struct blk_mq_hw_ctx *hctx;
-
-	hctx = container_of(work, struct blk_mq_hw_ctx, delayed_run_work.work);
-
+	hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
 	__blk_mq_run_hw_queue(hctx);
 }
 
@@ -1898,8 +1884,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
 	if (node == NUMA_NO_NODE)
 		node = hctx->numa_node = set->numa_node;
 
-	INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
-	INIT_DELAYED_WORK(&hctx->delayed_run_work, blk_mq_delayed_run_work_fn);
+	INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
 	INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
 	spin_lock_init(&hctx->lock);
 	INIT_LIST_HEAD(&hctx->dispatch);

include/linux/blk-mq.h

@@ -15,7 +15,7 @@ struct blk_mq_hw_ctx {
 		unsigned long		state;		/* BLK_MQ_S_* flags */
 	} ____cacheline_aligned_in_smp;
 
-	struct work_struct	run_work;
+	struct delayed_work	run_work;
 	cpumask_var_t		cpumask;
 	int			next_cpu;
 	int			next_cpu_batch;
@@ -51,7 +51,6 @@ struct blk_mq_hw_ctx {
 
 	atomic_t		nr_active;
 
-	struct delayed_work	delayed_run_work;
 	struct delayed_work	delay_work;
 
 	struct hlist_node	cpuhp_dead;