block: rename blk_mq_freeze_queue_start()

As the .q_usage_counter is used by both legacy and
mq path, we need to block new I/O if queue becomes
dead in blk_queue_enter().

So rename it and we can use this function in both
paths.

Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-core.c

@@ -670,7 +670,7 @@ int blk_queue_enter(struct request_queue *q, bool nowait)
 			return -EBUSY;
 
 		/*
-		 * read pair of barrier in blk_mq_freeze_queue_start(),
+		 * read pair of barrier in blk_freeze_queue_start(),
 		 * we need to order reading __PERCPU_REF_DEAD flag of
 		 * .q_usage_counter and reading .mq_freeze_depth,
 		 * otherwise the following wait may never return if the

block/blk-mq.c

@@ -68,7 +68,7 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
 	sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
 }
 
-void blk_mq_freeze_queue_start(struct request_queue *q)
+void blk_freeze_queue_start(struct request_queue *q)
 {
 	int freeze_depth;
 
@@ -78,7 +78,7 @@ void blk_mq_freeze_queue_start(struct request_queue *q)
 		blk_mq_run_hw_queues(q, false);
 	}
 }
-EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
+EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
 
 void blk_mq_freeze_queue_wait(struct request_queue *q)
 {
@@ -108,7 +108,7 @@ void blk_freeze_queue(struct request_queue *q)
 	 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
 	 * exported to drivers as the only user for unfreeze is blk_mq.
 	 */
-	blk_mq_freeze_queue_start(q);
+	blk_freeze_queue_start(q);
 	blk_mq_freeze_queue_wait(q);
 }
 
@@ -746,7 +746,7 @@ static void blk_mq_timeout_work(struct work_struct *work)
 	 * percpu_ref_tryget directly, because we need to be able to
 	 * obtain a reference even in the short window between the queue
 	 * starting to freeze, by dropping the first reference in
-	 * blk_mq_freeze_queue_start, and the moment the last request is
+	 * blk_freeze_queue_start, and the moment the last request is
 	 * consumed, marked by the instant q_usage_counter reaches
 	 * zero.
 	 */
@@ -2376,7 +2376,7 @@ static void blk_mq_queue_reinit_work(void)
 	 * take place in parallel.
 	 */
 	list_for_each_entry(q, &all_q_list, all_q_node)
-		blk_mq_freeze_queue_start(q);
+		blk_freeze_queue_start(q);
 	list_for_each_entry(q, &all_q_list, all_q_node)
 		blk_mq_freeze_queue_wait(q);
 

drivers/block/mtip32xx/mtip32xx.c

@@ -4162,7 +4162,7 @@ static int mtip_block_remove(struct driver_data *dd)
 		dev_info(&dd->pdev->dev, "device %s surprise removal\n",
 						dd->disk->disk_name);
 
-	blk_mq_freeze_queue_start(dd->queue);
+	blk_freeze_queue_start(dd->queue);
 	blk_mq_stop_hw_queues(dd->queue);
 	blk_mq_tagset_busy_iter(&dd->tags, mtip_no_dev_cleanup, dd);
 

drivers/nvme/host/core.c

@@ -2386,7 +2386,7 @@ void nvme_start_freeze(struct nvme_ctrl *ctrl)
 
 	mutex_lock(&ctrl->namespaces_mutex);
 	list_for_each_entry(ns, &ctrl->namespaces, list)
-		blk_mq_freeze_queue_start(ns->queue);
+		blk_freeze_queue_start(ns->queue);
 	mutex_unlock(&ctrl->namespaces_mutex);
 }
 EXPORT_SYMBOL_GPL(nvme_start_freeze);

include/linux/blk-mq.h

@@ -243,7 +243,7 @@ void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
 		busy_tag_iter_fn *fn, void *priv);
 void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_unfreeze_queue(struct request_queue *q);
-void blk_mq_freeze_queue_start(struct request_queue *q);
+void blk_freeze_queue_start(struct request_queue *q);
 void blk_mq_freeze_queue_wait(struct request_queue *q);
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 				     unsigned long timeout);