drbd: fix rmmod cleanup, remove _all_ debugfs entries

If there are still resources defined, but "empty", no more volumes
or connections configured, they don't hold module reference counts,
so rmmod is possible.

To avoid DRBD leftovers in debugfs, we need to call our global
drbd_debugfs_cleanup() only after all resources have been cleaned up.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -2420,7 +2420,6 @@ static void drbd_cleanup(void)
 		destroy_workqueue(retry.wq);
 
 	drbd_genl_unregister();
-	drbd_debugfs_cleanup();
 
 	idr_for_each_entry(&drbd_devices, device, i)
 		drbd_delete_device(device);
@@ -2431,6 +2430,8 @@ static void drbd_cleanup(void)
 		drbd_free_resource(resource);
 	}
 
+	drbd_debugfs_cleanup();
+
 	drbd_destroy_mempools();
 	unregister_blkdev(DRBD_MAJOR, "drbd");