Re: mount -f regression in v2.21's new-mount

Karel Zak
2012-03-09T12:29:29Z

On Fri, Mar 09, 2012 at 04:30:02AM -0700, Matthew Burgess wrote:
> On Fri, 9 Mar 2012 11:53:04 +0100, Karel Zak <kzak@redhat.com> wrote:
> > On Thu, Mar 08, 2012 at 08:25:00PM +0000, Matt Burgess wrote:
> >> I've attached LIBMOUNT_DEBUG output from the 'mount -a' call that our
> >> bootscript does. Note how mount correctly detects that /proc, /sys
> >
> > No, it calls mount(2) syscall for /proc. The problem is that the
> > detection code expects /proc/self/mountinfo (used on systems with
> > mtab -> /proc/mounts symlink), but your system uses regular mtab.
> >
> > I'll fix it. Thanks.

Fixed, try git pull.

> Thanks! Is there a consensus opinion on whether users should be
> using a regular mtab or a symlink to /proc/self/mountinfo?

- disadvantage is that some userspace utils (e.g. df(1) are not able
to de-duplicate list of mounted filesystem (bind mounts))

+ advantage is that there is only one list of mounted filesystems
with always valid mount options (on systems with mtab is not problem
to have 'rw' in mtab for read-only NFS, etc.), no problems with
namespaces, not writable files in /etc, no mtab lock, etc.

The symlink is required for systemd.

Karel

--
Karel Zak <kzak@redhat.com>