block: extend queue_flag bitops

Add test_and_clear and test_and_set.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-core.c

@@ -205,8 +205,7 @@ void blk_plug_device(struct request_queue *q)
 	if (blk_queue_stopped(q))
 		return;
 
-	if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
-		__set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
+	if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
 		mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
 		blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
 	}
@@ -221,10 +220,9 @@ int blk_remove_plug(struct request_queue *q)
 {
 	WARN_ON(!irqs_disabled());
 
-	if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
+	if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
 		return 0;
 
-	queue_flag_clear(QUEUE_FLAG_PLUGGED, q);
 	del_timer(&q->unplug_timer);
 	return 1;
 }
@@ -328,8 +326,7 @@ void blk_start_queue(struct request_queue *q)
 	 * one level of recursion is ok and is much faster than kicking
 	 * the unplug handling
 	 */
-	if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
-		queue_flag_set(QUEUE_FLAG_REENTER, q);
+	if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
 		q->request_fn(q);
 		queue_flag_clear(QUEUE_FLAG_REENTER, q);
 	} else {
@@ -394,8 +391,7 @@ void __blk_run_queue(struct request_queue *q)
 	 * handling reinvoke the handler shortly if we already got there.
 	 */
 	if (!elv_queue_empty(q)) {
-		if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
-			queue_flag_set(QUEUE_FLAG_REENTER, q);
+		if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
 			q->request_fn(q);
 			queue_flag_clear(QUEUE_FLAG_REENTER, q);
 		} else {

include/linux/blkdev.h

@@ -428,6 +428,32 @@ static inline void queue_flag_set_unlocked(unsigned int flag,
 	__set_bit(flag, &q->queue_flags);
 }
 
+static inline int queue_flag_test_and_clear(unsigned int flag,
+					    struct request_queue *q)
+{
+	WARN_ON_ONCE(!queue_is_locked(q));
+
+	if (test_bit(flag, &q->queue_flags)) {
+		__clear_bit(flag, &q->queue_flags);
+		return 1;
+	}
+
+	return 0;
+}
+
+static inline int queue_flag_test_and_set(unsigned int flag,
+					  struct request_queue *q)
+{
+	WARN_ON_ONCE(!queue_is_locked(q));
+
+	if (!test_bit(flag, &q->queue_flags)) {
+		__set_bit(flag, &q->queue_flags);
+		return 0;
+	}
+
+	return 1;
+}
+
 static inline void queue_flag_set(unsigned int flag, struct request_queue *q)
 {
 	WARN_ON_ONCE(!queue_is_locked(q));