Re: [Vserver] Unexpected behaviour with bind mounts

From: Herbert Poetzl <>
Date: Tue 11 Oct 2005 - 17:15:59 BST
Message-ID: <>

On Tue, Oct 11, 2005 at 02:38:20PM +0100, Jim Wight wrote:
> On Mon, 2005-10-10 at 20:09 +0200, Herbert Poetzl wrote:
> > On Mon, Oct 10, 2005 at 02:28:01PM +0100, Jim Wight wrote:
> > > Implicit unmounts are not happening in my case. If I start and stop the
> > > vserver a number of times I end up with a pile of multiple identical
> > > mounts (according to df), but as I mentioned in my original message
> > > there are no corresponding entries in /proc/mounts (as there are when I
> > > perform the same mounts manually). The other odd thing is that df shows
> > > different numbers compared with the manual mount case: it shows the
> > > numbers for the filesystem that the mount point is in, rather than for
> > > the mounted filesystem.
> >
> > hmm .. maybe you want to use the -n option to
> > mount, so that mount does not write stuff to
> > the mtab file?
> That has certainly got rid of the messages and odd-looking df output,
> but is it a case of 'out of sight, out of mind'? The mounts do work - so
> far - but is it normal to have to use -n? I don't think I've ever seen
> it mentioned in all the searching I've done trying to find out how to do
> things.

really depends on _what_ you do and _what_ you want ...

you should keep in mind that most tools (mount, df, ...)
look at /etc/mtab and not the /proc/mounts ...

the logic behind is simple: you want to keep /etc/mtab
and /proc/mounts in sync ...

this results in the following rules:

 - if you mount something on the host, you don't want -n
 - if you mount something for the guest, you definitely
   want -n for the host's mtab
 - if you mount something inside the guest, you don't
   want -n for the guest's mtab

basically it's standard namespace behaviour, not even
vserver related (i.e. you can observe the same with
plain namespaces and chroot ...


> Jim
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Received on Tue Oct 11 17:16:20 2005

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