diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ce2d797..c1ad0b0 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3044,9 +3044,11 @@
 		return -EINVAL;
 	}
 
-	err = md_allow_write(mddev);
-	if (err)
-		return err;
+	if (!mddev_is_clustered(mddev)) {
+		err = md_allow_write(mddev);
+		if (err)
+			return err;
+	}
 
 	raid_disks = mddev->raid_disks + mddev->delta_disks;