[buildd-tools-devel] Some schroot (union) fixes

[Roger Leigh]

On Mon, Aug 03, 2009 at 02:05:45PM +0200, Jan-Marek Glogowski wrote:
> On Sat, 1 Aug 2009, Roger Leigh wrote:
> 
> > I've applied most of the patches now.  Could you please check if this is
> > working correctly for you.
> >
> > [PATCH 03/11] [sbuild_session] Don't rollback non-run scripts
> >
> > Not applied.  I still have significant issues with this patch, as I've
> > mentioned previously:
> >
> >   Again, I don't understand what this gains us.
> 
> With a negative intention: it papers over a bug with non-union loopback
> chroot. I don't see the point in stoping a script which didn't even start.
> 
> 1. Start a session "chroot -c loop" -> ok (id1)
> 2. Open a second terminal
> 3. Start a second session "chroot -c loop" -> fails and kills session id1
> 
> As it's written in the comment to the patch, I guess it's an error in the
> 15killprocs script, which kills the first sessions processes.
> 
> So without the patch, the whole "stop" stack is run happily killing the
> first session. With the patch, the first session is preserved and the
> second fails.

Ah, I see.  This is definitely a bug in the setup script which needs
fixing.  I think, however, that the facet migration will have fixed it
as a side-effect.  loopback chroots now start a separate session for
each invocation where previously they shared a common mount location,
which is why 15killprocs would kill the processes from the first
session.  Now, they will share the underlying loopback device, but
due to being separate sessions there should not be any unintentional
killing since the mount location in which all processes are killed is
entirely separate.


Regards,
Roger

-- 
  .''`.  Roger Leigh
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