block: Introduce blk_queue_flag_{set,clear,test_and_{set,clear}}()

Introduce functions that modify the queue flags and that protect
these modifications with the request queue lock. Except for moving
one wake_up_all() call from inside to outside a critical section,
this patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 75 insertions, 16 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 241b73088617..74c6283f4509 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -71,6 +71,78 @@ struct kmem_cache *blk_requestq_cachep;
  */
 static struct workqueue_struct *kblockd_workqueue;
 
+/**
+ * blk_queue_flag_set - atomically set a queue flag
+ * @flag: flag to be set
+ * @q: request queue
+ */
+void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	queue_flag_set(flag, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+EXPORT_SYMBOL(blk_queue_flag_set);
+
+/**
+ * blk_queue_flag_clear - atomically clear a queue flag
+ * @flag: flag to be cleared
+ * @q: request queue
+ */
+void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	queue_flag_clear(flag, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+EXPORT_SYMBOL(blk_queue_flag_clear);
+
+/**
+ * blk_queue_flag_test_and_set - atomically test and set a queue flag
+ * @flag: flag to be set
+ * @q: request queue
+ *
+ * Returns the previous value of @flag - 0 if the flag was not set and 1 if
+ * the flag was already set.
+ */
+bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
+{
+	unsigned long flags;
+	bool res;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	res = queue_flag_test_and_set(flag, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	return res;
+}
+EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
+
+/**
+ * blk_queue_flag_test_and_clear - atomically test and clear a queue flag
+ * @flag: flag to be cleared
+ * @q: request queue
+ *
+ * Returns the previous value of @flag - 0 if the flag was not set and 1 if
+ * the flag was set.
+ */
+bool blk_queue_flag_test_and_clear(unsigned int flag, struct request_queue *q)
+{
+	unsigned long flags;
+	bool res;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	res = queue_flag_test_and_clear(flag, q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	return res;
+}
+EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_clear);
+
 static void blk_clear_congested(struct request_list *rl, int sync)
 {
 #ifdef CONFIG_CGROUP_WRITEBACK
@@ -361,25 +433,14 @@ EXPORT_SYMBOL(blk_sync_queue);
  */
 int blk_set_preempt_only(struct request_queue *q)
 {
-	unsigned long flags;
-	int res;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	res = queue_flag_test_and_set(QUEUE_FLAG_PREEMPT_ONLY, q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-
-	return res;
+	return blk_queue_flag_test_and_set(QUEUE_FLAG_PREEMPT_ONLY, q);
 }
 EXPORT_SYMBOL_GPL(blk_set_preempt_only);
 
 void blk_clear_preempt_only(struct request_queue *q)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q);
+	blk_queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q);
 	wake_up_all(&q->mq_freeze_wq);
-	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL_GPL(blk_clear_preempt_only);
 
@@ -629,9 +690,7 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
 
 void blk_set_queue_dying(struct request_queue *q)
 {
-	spin_lock_irq(q->queue_lock);
-	queue_flag_set(QUEUE_FLAG_DYING, q);
-	spin_unlock_irq(q->queue_lock);
+	blk_queue_flag_set(QUEUE_FLAG_DYING, q);
 
 	/*
 	 * When queue DYING flag is set, we need to block new req