block: Move the second call to get_request to the end of the loop

In function get_request_wait, the second call to get_request could be moved to the end of the while loop, because if the first call to get_request fails, the second call will fail without sleep. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block: Move the second call to get_request to the end of the loop
In function get_request_wait, the second call to get_request could be moved to the end of the while loop, because if the first call to get_request fails, the second call will fail without sleep. Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Zhang, Yanmin · Jens Axboe
1 parent ca39d651d1
Showing 1 changed file with 17 additions and 20 deletions Side-by-side Diff
block/blk-core.c
@@ -806,35 +806,32 @@
 	rq = get_request(q, rw_flags, bio, GFP_NOIO);
 	while (!rq) {
 		DEFINE_WAIT(wait);
+		struct io_context *ioc;
 		struct request_list *rl = &q->rq;
  
 		prepare_to_wait_exclusive(&rl->wait[rw], &wait,
 				TASK_UNINTERRUPTIBLE);
  
-		rq = get_request(q, rw_flags, bio, GFP_NOIO);
+		blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
  
-		if (!rq) {
-			struct io_context *ioc;
+		__generic_unplug_device(q);
+		spin_unlock_irq(q->queue_lock);
+		io_schedule();
  
-			blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
+		/*
+		 * After sleeping, we become a "batching" process and
+		 * will be able to allocate at least one request, and
+		 * up to a big batch of them for a small period time.
+		 * See ioc_batching, ioc_set_batching
+		 */
+		ioc = current_io_context(GFP_NOIO, q->node);
+		ioc_set_batching(q, ioc);
  
-			__generic_unplug_device(q);
-			spin_unlock_irq(q->queue_lock);
-			io_schedule();
-
-			/*
-			 * After sleeping, we become a "batching" process and
-			 * will be able to allocate at least one request, and
-			 * up to a big batch of them for a small period time.
-			 * See ioc_batching, ioc_set_batching
-			 */
-			ioc = current_io_context(GFP_NOIO, q->node);
-			ioc_set_batching(q, ioc);
-
-			spin_lock_irq(q->queue_lock);
-		}
+		spin_lock_irq(q->queue_lock);
 		finish_wait(&rl->wait[rw], &wait);
-	}
+
+		rq = get_request(q, rw_flags, bio, GFP_NOIO);
+	};
  
 	return rq;
 }
...	...	@@ -806,35 +806,32 @@
806	806	rq = get_request(q, rw_flags, bio, GFP_NOIO);
807	807	while (!rq) {
808	808	DEFINE_WAIT(wait);
	809	+ struct io_context *ioc;
809	810	struct request_list *rl = &q->rq;
810	811
811	812	prepare_to_wait_exclusive(&rl->wait[rw], &wait,
812	813	TASK_UNINTERRUPTIBLE);
813	814
814		- rq = get_request(q, rw_flags, bio, GFP_NOIO);
	815	+ blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
815	816
816		- if (!rq) {
817		- struct io_context *ioc;
	817	+ __generic_unplug_device(q);
	818	+ spin_unlock_irq(q->queue_lock);
	819	+ io_schedule();
818	820
819		- blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
	821	+ /*
	822	+ * After sleeping, we become a "batching" process and
	823	+ * will be able to allocate at least one request, and
	824	+ * up to a big batch of them for a small period time.
	825	+ * See ioc_batching, ioc_set_batching
	826	+ */
	827	+ ioc = current_io_context(GFP_NOIO, q->node);
	828	+ ioc_set_batching(q, ioc);
820	829
821		- __generic_unplug_device(q);
822		- spin_unlock_irq(q->queue_lock);
823		- io_schedule();
824		-
825		- /*
826		- * After sleeping, we become a "batching" process and
827		- * will be able to allocate at least one request, and
828		- * up to a big batch of them for a small period time.
829		- * See ioc_batching, ioc_set_batching
830		- */
831		- ioc = current_io_context(GFP_NOIO, q->node);
832		- ioc_set_batching(q, ioc);
833		-
834		- spin_lock_irq(q->queue_lock);
835		- }
	830	+ spin_lock_irq(q->queue_lock);
836	831	finish_wait(&rl->wait[rw], &wait);
837		- }
	832	+
	833	+ rq = get_request(q, rw_flags, bio, GFP_NOIO);
	834	+ };
838	835
839	836	return rq;
840	837	}