Re: pivot_root solved by patch to 2.4.22-pre7

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Wed Aug 06 2003 - 14:33:52 EST


What is your problem with pivot_root?

Sorry but I've searched the list archives and found nothing but this email
and this patch, which seems a bit hackish.

On Wed, 6 Aug 2003, Rene Mayrhofer wrote:

> Hi all,
>
> The problem with pivot_root that appeared in 2.4.21-ac4 and the
> 2.4.22-pre kernels is now solved (at least for my case) by applying the
> trvial patch sent by Jason Baron.
>
> Jason Baron wrote:
> > right. so the semantics of how file tables are shared has changed a bit. I
> > would think that for at least 'init', it'd be nice to preserve the
> > original behavior, for situations such as you described. Something like
> > the following would probably work, although i havent' tried the test
> > script.
> >
> > --- linux/kernel/fork.c.orig 2003-07-23 21:34:59.000000000 -0400
> > +++ linux/kernel/fork.c 2003-07-23 21:35:45.000000000 -0400
> > @@ -558,7 +558,7 @@ int unshare_files(void)
> >
> > /* This can race but the race causes us to copy when we don't
> > need to and drop the copy */
> > - if(atomic_read(&files->count) == 1)
> > + if(atomic_read(&files->count) == 1 || (current->pid == 1))
> > {
> > atomic_inc(&files->count);
> > return 0;
> >
>
>
>
> I tried that on my system and it works as expected. The kernel processes
> close their fds and the old root fs can thus be unmounted after
> pivot_root. Thanks for the hint !
> So the problem is solved for me and it would be wonderful to get it into
> 2.4.22.
>
> best regards,
> Rene
>
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