Re: automount doesn't "follow" bind mounts

H. Peter Anvin
2002-08-20T21:31:32Z

Followup to: <ajuahu$hf$1@cesium.transmeta.com>
By author: "H. Peter Anvin" <hpa@zytor.com>
In newsgroup: linux.dev.kernel
>
> Followup to: <Pine.LNX.4.44.0208201752430.23681-100000@r2-pc.dcs.qmul.ac.uk>
> By author: Matt Bernstein <mb/lkml@dcs.qmul.ac.uk>
> In newsgroup: linux.dev.kernel
> >
> > I tried to subscribe to the autofs list, but majordomo isn't replying to
> > me! I think this is a problem in the automount daemon rather than the
> > kernel autofs code itself.
> >
> > I'm trying to automount our home dirs as
> > /homes/$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.)
>

Actually, if you're using autofs v3, which it sounds like you're
doing, it's even more broken, since autofs v3 doesn't support
multilevel mounts.

-hpa
--
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