Note error when FFS does not support whiteouts and how to fix. (PR 3233)

Author: phil

sbin/mount_union/mount_union.8

@@ -1,4 +1,4 @@
-.\"	$NetBSD: mount_union.8,v 1.5 1996/01/15 02:00:21 thorpej Exp $
+.\"	$NetBSD: mount_union.8,v 1.6 1997/06/30 20:06:39 phil Exp $
 .\"
 .\" Copyright (c) 1994
 .\" The Regents of the University of California.  All rights reserved.
@@ -182,15 +182,21 @@ accessible via
 .Xr unmount 2 ,
 .Xr fstab 5 ,
 .Xr mount 8 ,
-.Xr mount_null 8
+.Xr mount_null 8 ,
+.Xr fsck_ffs 8
 .Sh BUGS
 Without whiteout support from the filesystem backing the upper layer,
 there is no way that delete and rename operations on lower layer
 objects can be done.
-.Dv EROFS
-is returned for this kind of operations along with any others
-which would make modifications to the lower layer, such as
-.Xr chmod 1 .
+An attempt to mount a union directory under one which does not
+have whiteout support will return
+.Dv EOPNOTSUPP
+(``Operation not supported'').
+Whiteout support can be added to an existing FFS filesystem
+by using the
+.Fl c
+option of
+.Xr fsck_ffs 8 .
 .Pp
 Running
 .Xr find 1