Re: why is the same mount point repeatedly mounted in nested manner?

[Chris Murphy <lists@colorremedies.com>]

On Sat, Aug 7, 2021 at 6:25 PM Adam Borowski <kilobyte@angband.pl> wrote:
>
> On Thu, Aug 05, 2021 at 04:41:03PM -0400, Dave T wrote:
> > On Thu, Aug 5, 2021 at 1:49 PM Phillip Susi <phill@thesusis.net> wrote:
> > > Dave T <davestechshop@gmail.com> writes:
> > >
> > > > I'm using btrbk via a systemd timer. I have a daily and hourly timer
> > > > set up. Each timer starts by mounting the btrfs root, performing the
> > > > btrbk task, and unmounting the btrfs root.
>
> > Not exactly... that path should not be unmounted. I do not mount that
> > location explicitly for the btrbk tasks. It is mounted when the server
> > boots up with the bind mount line I showed in fstab:
> >
> > /var/cache/pacman       /srv/nfs/var/cache/pacman       none  bind  0 0
> >
> > It should not be unmounted (or remounted) just because the top level
> > btrfs volume is (un)mounted for btrbk tasks. That's the part that is
> > confusing me.
> >
> > There is no command associated with my btrbk tasks that mounts
> > /srv/nfs/var/cache/pacman (or /var/cache/pacman). There's no other
> > entry in fstab for it except the bind mount I showed.
>
> I've seen systemd randomly mount and/or unmount filesystems listed in fstab
> when their state somehow differs from what systemd thinks should be (which
> can happen either by you or a program doing a mount, or due to systemd
> misreading the state reported by the kernel).
>
> So I wonder, can you test with an init/rc other than systemd?

We just need logs, systemd will put a message that it's mounting
something into the journal: journalctl -b --no-hostname | grep mount


-- 
Chris Murphy