Re: automount doesn't "follow" bind mounts

H. Peter Anvin
2002-08-20T20:54:58Z

Followup to: <Pine.LNX.4.44.0208201752430.23681-100000@r2-pc.dcs.qmul.ac.uk>
By author: Matt Bernstein <mb/lkml@dcs.qmul.ac.uk>
In newsgroup: linux.dev.kernel
>
> I tried to subscribe to the autofs list, but majordomo isn't replying to
> me! I think this is a problem in the automount daemon rather than the
> kernel autofs code itself.
>
> I'm trying to automount our home dirs as
> /homes/$USERNAME
> which should bind mount to
> :/home/$SERVER/$HOMENAME/$USERNAME
> which should bind mount to
> :/home/$SERVER/$VOLUME/$PATH/$USERNAME
> which (phew!) will be an NFS mount to
> $SERVER:/$VOLUME/$PATH/$USERNAME
>
> The idea is that:
> (1) `/bin/pwd` = "/homes/$USERNAME"
> (2) when you run "quota" it'll only report for $SERVER:/$VOLUME
>
> Now.. this all works perfectly if before looking at /homes/$USERNAME you
> look at firstly /home/$SERVER/$VOLUME/$PATH/$USERNAME and then secondly
> /home/$SERVER/$HOMENAME/$USERNAME, because the bind mounts have something
> to bind to. Of course you shouldn't need to know the middle bits, but you
> could look them up. Currently the binds mount fail and automount drops in
> symlinks; this satisfies (2) above, but unfortunately not (1).
>
> I hope someone can make sense of this. Is it different in autofs4?
>

This is unfortunately nearly impossible to solve. It's a known bug,
but it's questionable if anything can be done about it.

For right now, autofs cannot bind-mount to a mount from the same
automount point (the problem is with the double-use of /home/$SERVER
in your case.)

-hpa
--
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"Unix gives you enough rope to shoot yourself in the foot."
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