diff --git a/src/ceph-disk-activate b/src/ceph-disk-activate
index 9ada2198ff5..ddfadebdfeb 100755
--- a/src/ceph-disk-activate
+++ b/src/ceph-disk-activate
@@ -347,6 +347,10 @@ def get_conf(cluster, variable):
 
 
 MOUNT_OPTIONS = dict(
+    # this is default ever since linux 2.6.39 / 3.0, but we'll delay a
+    # moment before removing it fully because we did have some issues
+    # with ext4 before the xatts-in-leveldb work, and it seemed that
+    # user_xattr helped
     ext4='user_xattr',
     )