systemd acceptance, packaging guidelines (was Re: systemd and changes)

[Lennart Poettering]

On Tue, 24.08.10 20:14, Matt McCutchen (matt at mattmccutchen.net) wrote:

> 
> On Tue, 2010-08-24 at 23:31 +0200, Lennart Poettering wrote:
> > On Tue, 24.08.10 16:38, Bill Nottingham (notting at redhat.com) wrote:
> > > Lennart Poettering (mzerqung at 0pointer.de) said: 
> > > > > - init shall support a mechanism to re-exec itself to not cause dirty
> > > > >   inodes on shutdown; initscripts will use this method on shutdown.
> > > > 
> > > > This is bad. While we support this just fine I think it is a really bad
> > > > idea to reexec init at shutdown. What's the point of this, can you elaborate on
> > > > this? This smells to me as a workaround for brokeness in older init
> > > > systems, and I don't see a reason why reexecing itself would be
> > > > necessary for systemd.
> > > 
> > > If the libraries or binaries used by systemd are replaced during runtime,
> > > and it is not re-executed on shutdown, the filesystem will have busy inodes
> > > on shutdown. (If you'd like to take the filesystem semantics up with the
> > > kernel, feel free to tilt at that windmill.)
> > 
> > Hmm, so this is about files that are deleted but still mapped by init,
> > and which can only be deleted when init stops referencing them, but that
> > is required to remount the fs r/o? Did I get this right?
> 
> Yes, that's right.
> 
> > I am not really convinced that reexecing is the right answer for this
> > problem. But well, since this already works anyway I guess this doesn't
> > really matter too much.
> 
> Indeed, it's a hack, but there's no better option in sight, so I don't
> see the point in complaining.

Well, what me still puzzles is this: the reexec is done asynchronously,
via signals. Shouldn't this be done synchronously at least to make
sure the daemon really is reexec'ed when we try to remount r/o?

Lennart

-- 
Lennart Poettering - Red Hat, Inc.