diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 9130d05..ab90a6d 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -565,6 +565,8 @@
 
 	if (disk >= 0 && (rdev=rcu_dereference(conf->mirrors[disk].rdev))!= NULL)
 		atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
+	else
+		disk = -1;
 	rcu_read_unlock();
 
 	return disk;