drbd: destroy workqueue when drbd device was freed

A submitter workqueue is dynamically allocated by init_submitter()
called by drbd_create_device(), we should destroy it when this
device is not needed or destroyed.

Fixes: 113fef9e ("drbd: prepare to queue write requests on a submit worker")
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lore.kernel.org/r/20221124015817.2729789-3-bobo.shaobowang@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -2217,6 +2217,8 @@ void drbd_destroy_device(struct kref *kref)
 		kref_put(&peer_device->connection->kref, drbd_destroy_connection);
 		kfree(peer_device);
 	}
+	if (device->submit.wq)
+		destroy_workqueue(device->submit.wq);
 	kfree(device);
 	kref_put(&resource->kref, drbd_destroy_resource);
 }
@@ -2771,7 +2773,7 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 
 	err = add_disk(disk);
 	if (err)
-		goto out_idr_remove_from_resource;
+		goto out_destroy_workqueue;
 
 	/* inherit the connection state */
 	device->state.conn = first_connection(resource)->cstate;
@@ -2785,6 +2787,8 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	drbd_debugfs_device_add(device);
 	return NO_ERROR;
 
+out_destroy_workqueue:
+	destroy_workqueue(device->submit.wq);
 out_idr_remove_from_resource:
 	for_each_connection(connection, resource) {
 		peer_device = idr_remove(&connection->peer_devices, vnr);