blk-mq: factor out some helps to quiesce/unquiesce queue

hulk inclusion
category: bugfix
bugzilla: 173974
CVE: NA
---------------------------

Prepare to support concurrent quiesce queue between drivers and block
layer, no functional changes.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

block/blk-mq.c

@@ -211,32 +211,29 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 
+static void __blk_mq_quiesce_queue_nowait(struct request_queue *q,
+					  unsigned int flag)
+{
+	blk_queue_flag_set(flag, q);
+}
+
 /*
  * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
  * mpt3sas driver such that this function can be removed.
  */
 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
 {
-	blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
+	__blk_mq_quiesce_queue_nowait(q, QUEUE_FLAG_QUIESCED);
 }
 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
 
-/**
- * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
- * @q: request queue.
- *
- * Note: this function does not prevent that the struct request end_io()
- * callback function is invoked. Once this function is returned, we make
- * sure no dispatch can happen until the queue is unquiesced via
- * blk_mq_unquiesce_queue().
- */
-void blk_mq_quiesce_queue(struct request_queue *q)
+static void __blk_mq_quiesce_queue(struct request_queue *q, unsigned int flag)
 {
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int i;
 	bool rcu = false;
 
-	blk_mq_quiesce_queue_nowait(q);
+	__blk_mq_quiesce_queue_nowait(q, flag);
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (hctx->flags & BLK_MQ_F_BLOCKING)
@@ -247,15 +244,30 @@ void blk_mq_quiesce_queue(struct request_queue *q)
 	if (rcu)
 		synchronize_rcu();
 }
+
+/**
+ * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
+ * @q: request queue.
+ *
+ * Note: this function does not prevent that the struct request end_io()
+ * callback function is invoked. Once this function is returned, we make
+ * sure no dispatch can happen until the queue is unquiesced via
+ * blk_mq_unquiesce_queue().
+ */
+void blk_mq_quiesce_queue(struct request_queue *q)
+{
+	__blk_mq_quiesce_queue(q, QUEUE_FLAG_QUIESCED);
+}
 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
 
-bool blk_mq_quiesce_queue_without_rcu(struct request_queue *q)
+static bool __blk_mq_quiesce_queue_without_rcu(struct request_queue *q,
+					       unsigned int flag)
 {
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int i;
 	bool rcu = false;
 
-	blk_mq_quiesce_queue_nowait(q);
+	__blk_mq_quiesce_queue_nowait(q, flag);
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (hctx->flags & BLK_MQ_F_BLOCKING)
@@ -265,8 +277,21 @@ bool blk_mq_quiesce_queue_without_rcu(struct request_queue *q)
 	}
 	return rcu;
 }
+
+bool blk_mq_quiesce_queue_without_rcu(struct request_queue *q)
+{
+	return __blk_mq_quiesce_queue_without_rcu(q, QUEUE_FLAG_QUIESCED);
+}
 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_without_rcu);
 
+static void __blk_mq_unquiesce_queue(struct request_queue *q, unsigned int flag)
+{
+	blk_queue_flag_clear(flag, q);
+
+	/* dispatch requests which are inserted during quiescing */
+	blk_mq_run_hw_queues(q, true);
+}
+
 /*
  * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
  * @q: request queue.
@@ -276,10 +301,7 @@ EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_without_rcu);
  */
 void blk_mq_unquiesce_queue(struct request_queue *q)
 {
-	blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
-
-	/* dispatch requests which are inserted during quiescing */
-	blk_mq_run_hw_queues(q, true);
+	__blk_mq_unquiesce_queue(q, QUEUE_FLAG_QUIESCED);
 }
 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);