Subject: Re: [vserver] autofs failing to umount in guest
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Tue, 29 Dec 2009 09:06:37 +0100

On Tue, Dec 29, 2009 at 05:24:07PM +1100, Fog_Watch wrote:
> On Mon, 28 Dec 2009 16:38:26 +0100
> Herbert Poetzl <herbert@13thfloor.at> wrote:

> snip
> > the fact that this works shows that the problem in your
> > setup is probably not Linux-VServer related, as there
> > should be no difference between manual umount and the
> > umount autofs does ...
> I don't know what it means, but there is a difference between manual
> umount and the umount autofs does inside my guest:
> hostname ~ # df | grep cdrom
> hostname ~ # cd /mnt/cdrom
> hostname cdrom # df | grep cdrom
> /dev/sr0                717098    717098         0
> 100% /mnt/removables/cdrom 
> hostname cdrom # cd ~
> hostname ~ # tail /var/log/syslog | grep umount
> Dec 29 11:26:41 hostname automount[10869]: umount_autofs_indirect: ask
> umount returned busy /mnt/removables 
> hostname ~ # umount /mnt/cdrom
> hostname ~ # df | grep cdrom
> hostname ~ #

> The umount autofs fails when in the guest. 
> In the host it succeeds.

try with chroot (from the host) into the guest
data (root dir), otherwise it is probably apples
and oranges ...

> snip
> > means something is holding a reference to some part of
> > the mount path, use fuser/lsof to identify obvious
> > userspace apps, but could be something not so obvious
> > (like e.g. the kernel nfs) as well

> The following suggests that lsof does not find anything obvious.

> hostname ~ # df | grep cdrom ; ls /mnt/cdrom ; df | grep cdrom ;
> lsof /mnt 
> Getting_Online.txt  docs          image.squashfs  livecd
> README.txt          gentoo.efimg  isolinux        snapshots
> /dev/sr0                717098    717098         0
> 100% /mnt/removables/cdrom 
> hostname ~ #

please try with lsof +d and lsof +D as well ...

> snip
> > I'd try without grsec or at least with grsec disabled
> Yes, grsec disabled.

> > you could simply put the autofs
> > on the host and make it blend through to the guest name
> > spaces ....
> This is a viable option.  
> You say, "blend through to the guest name
> spaces".  Hmmmm.  Is this a vnamespace idea?

it's a namesapce concept in general, i.e. not
Linux-VServer specific ...

best,
Herbert

> On Mon, 28 Dec 2009 16:39:21 +0100
> Herbert Poetzl <herbert@13thfloor.at> wrote:

> > might help to compare kernel/automount versions?
> Joe, your versions?

> Regards
> Fog_Watch.

> -- 
> Lose wait.  Get Gentoo.