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Date: Fri, 28 Jul 1995 10:18:14 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199507280018.KAA01775@godzilla.zeta.org.au>
To: hackers@FreeBSD.org, jmacd@uclink.berkeley.edu
Subject: Re: unionfs
Sender: hackers-owner@FreeBSD.org
Precedence: bulk

>does unionfs work?

Nope.

>I just tried mounting a CD and union mounting another filesystem
>on top of it, following the directions in the man page for mount_union.
>I mounted /dev/cd0a on /usr/src and then did
>mount -t union /usr/obj /usr/src and now df reports:
>...
><above>/usr/obj    910807   721901   165112    81%    /usr/src

>and there is nothing showing in /usr/src, nor can I figure out how

readdir() doesn't work for the lkm'ed version, so ls won't show anything,
but at files in at least the top level directory can be opened if you
know their name.

readdir() works in the kernel version, but making /usr/src after following
the directions in the man page hung after a few seconds when I tried it
a few months ago.

>to umount it either.  because if I change directories to /usr/src
>it says I'm in /usr/obj and umount /usr/src says /usr/obj isn't 
>mounted.

This may be correct.  The semantics of union mounts are confusing at first.
Unmount seemed to work when I tried it.

Bruce