block: Avoid that sparse complains about context imbalance in __wbt_wait()

This patch does not change any functionality.

Fixes: e34cbd30 ("blk-wbt: add general throttling mechanism")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-wbt.c

@@ -544,6 +544,8 @@ static inline bool may_queue(struct rq_wb *rwb, struct rq_wait *rqw,
  * the timer to kick off queuing again.
  */
 static void __wbt_wait(struct rq_wb *rwb, unsigned long rw, spinlock_t *lock)
+	__releases(lock)
+	__acquires(lock)
 {
 	struct rq_wait *rqw = get_rq_wait(rwb, current_is_kswapd());
 	DEFINE_WAIT(wait);
@@ -558,13 +560,12 @@ static void __wbt_wait(struct rq_wb *rwb, unsigned long rw, spinlock_t *lock)
 		if (may_queue(rwb, rqw, &wait, rw))
 			break;
 
-		if (lock)
+		if (lock) {
 			spin_unlock_irq(lock);
-
 			io_schedule();
-
-		if (lock)
 			spin_lock_irq(lock);
+		} else
+			io_schedule();
 	} while (1);
 
 	finish_wait(&rqw->wait, &wait);