diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 81631e17f4a040d67cf5e6132eca6c26cd342afb..f05417673bf2ab0f92cac2e30cfc8dbf70fab78e 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1725,6 +1725,8 @@ void md_bitmap_flush(struct mddev *mddev)
 	md_bitmap_daemon_work(mddev);
 	bitmap->daemon_lastrun -= sleep;
 	md_bitmap_daemon_work(mddev);
+	if (mddev->bitmap_info.external)
+		md_super_wait(mddev);
 	md_bitmap_update_sb(bitmap);
 }