[systemd-devel] Shared root fs by default

[Tvrtko Ursulin]

On Friday 05 April 2013 18:23:35 Lennart Poettering wrote:
> On Fri, 05.04.13 17:19, Tvrtko Ursulin (tvrtko.ursulin at onelan.co.uk) wrote:
> > > Hmm, does this always happen this way, or is the MS_REC flag "sticky"
> > > and causes the MNT_DETACH to be recursive?
> > > 
> > > That looks a bit like a kernel misfeature, no?
> > 
> > To me it looks like the kernel is working as designed, but perhaps I am
> > not
> > getting what exactly are you asking. You can read all the details in about
> > shared mounts and event propagation in
> > Documentation/filesystems/sharedsubtree.txt.
> > 
> > Use case described there is that if you clone (bind) a shared tree you
> > need to make it a slave to shut down the propagation in the backward
> > direction (it's bi-directional for shared trees by default).
> 
> Well, but in your example you unmounted a bind mount with a child, and
> that resulted in the unmounting of the child in the source mount, too --
> even though you never asked for that child mount to be unmounted. That's
> what your example showed, right?

Yes, but as I said, after a quick glance at kernel docs I got the impression 
that is what should happen. I could be wrong though. Perhaps we should try and 
drag into discussion someone who designed this.

Regards,

Tvrtko