nvme: add APIs for stopping/starting admin queue

Add two APIs for stopping and starting admin queue.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211014081710.1871747-2-ming.lei@redhat.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/core.c

@@ -4579,6 +4579,18 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
 }
 EXPORT_SYMBOL_GPL(nvme_start_queues);
 
+void nvme_stop_admin_queue(struct nvme_ctrl *ctrl)
+{
+	blk_mq_quiesce_queue(ctrl->admin_q);
+}
+EXPORT_SYMBOL_GPL(nvme_stop_admin_queue);
+
+void nvme_start_admin_queue(struct nvme_ctrl *ctrl)
+{
+	blk_mq_unquiesce_queue(ctrl->admin_q);
+}
+EXPORT_SYMBOL_GPL(nvme_start_admin_queue);
+
 void nvme_sync_io_queues(struct nvme_ctrl *ctrl)
 {
 	struct nvme_ns *ns;

drivers/nvme/host/nvme.h

@@ -679,6 +679,8 @@ void nvme_complete_async_event(struct nvme_ctrl *ctrl, __le16 status,
 
 void nvme_stop_queues(struct nvme_ctrl *ctrl);
 void nvme_start_queues(struct nvme_ctrl *ctrl);
+void nvme_stop_admin_queue(struct nvme_ctrl *ctrl);
+void nvme_start_admin_queue(struct nvme_ctrl *ctrl);
 void nvme_kill_queues(struct nvme_ctrl *ctrl);
 void nvme_sync_queues(struct nvme_ctrl *ctrl);
 void nvme_sync_io_queues(struct nvme_ctrl *ctrl);