[Buildd-tools-devel] schroot unionfs support

Jan-Marek Glogowski glogow at fbihome.de
Fri Mar 20 08:39:41 UTC 2009


> On Wed, 18 Mar 2009, Tim Abbott wrote:
>
> This version of schroot basically works in my environment.  The one
> problem that I had was that the aufs mount options didn't work my setting,
> in particular, the ",udba=inotify" option in the branch configuration
> causes aufs mounting to not work (output below).
>
> If one removes the "udba=inotify", then schroot works.  From the
> documentation I get the impression that "udba=inotify" tries to protect a
> chroot from having problems if one changes the source chroot, so we may
> want to figure out what's actually going on here.  Jan-Marek, is this
> issue familiar to you?
>
> 	-Tim Abbott
>
> tabbott at coset:/tmp/modules/aufs$ schroot -c lenny-i386
> mount: wrong fs type, bad option, bad superblock on
> lenny-i386-e3a487a4-d0f8-4289-a384-22e3eaf5b629,
>        missing codepage or helper program, or other error
>        (for several filesystems (e.g. nfs, cifs) you might
>        need a /sbin/mount.<type> helper program)
>        In some cases useful info is found in syslog - try
>        dmesg | tail  or so
>
> Mounting filesystem union failed
> E: lenny-i386-e3a487a4-d0f8-4289-a384-22e3eaf5b629: Chroot setup failed: stage=setup-start
> tabbott at coset
>
> /var/log/dmesg gets the following:
> [30658.919026] aufs au_opts_parse:974:mount[2561]: wrong value, udba=inotify

I just had a look at the aufs source in Lenny. The module is not compiled
with inotify support, so the option isn't recognized. On the other hand
one probably shouldn't edit the "source" while an aufs session is running,
so the udba attribute can be omitted.

Inotify support costs some performance (just when selected as a mount
option, not when compiled in).

See the aufs.5 manpage for further information about "User's Direct
Branch Access (UDBA)".

Jan-Marek Glogowski



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