shutdown busybox and start another PID1 process

[Sam Liddicott]

I wonder if cgroups or namespaces have any role here.

The initrd mounts NTFS and then creates a new namespace for new init which
can't see or kill fuse.

Sam
On 11 Aug 2014 17:34, "James B" <jamesbond3142 at gmail.com> wrote:

> Hi James (from another James).
>
> On Mon, 11 Aug 2014 03:17:52 -0600
> James Bowlin <bitjam at gmail.com> wrote:
>
> >
> > There was a need to have static root persistence where the
> > changes are saved directly in the root persistence file so I
> > needed to bite the bullet and finally get clean umounts during
> > shutdown.
> >
> > Previously, filesystems were consistently reporting they were
> > uncleanly mounted.  I wanted to do it all cleanly.  I tried like
> > crazy to get remounting read-only to work but I just could not do
> > it.  Maybe the problem was that I couldn't remount the rw file
> > system under the aufs as ro (because the aufs was rw) and I
> > couldn't remount the aufs as ro because its mount options are
> > unconventional.
>
> This is a solved problem. Fatdog64, an 64-bit offshot of Puppy Linux
> (disclaimer: I'm one of the maintainers), does exactly this - and have
> clean unmounts on common filesystems - fat32, ext2/3/4, ntfs (through
> ntfs-3g). The key is to remount ro the aufs layers; once made ro you can
> "unbind" them one by one (including the r/w layer). This ability to
> dynamically bind/unbind layers is one of the thing that makes me loves aufs
> so much - it is so much more versatile than any other layered filesystem
> out there *combined*. Get the ISO and take a look at its
> /etc/rc.d/rc.cleanup if you're interested.
>
> >
> > Well busybox has all the tools I need.  The tmpfs gives me a place
> > to stand so I can move the world^H^H aufs file system. It gives me
> > a place where my tools and everything I need are off of the aufs.
>
> Agreed, busybox is all you need.
>
> >
> > I pivot onto a tmpfs that has the busybox stuff and very little
> > else.  Root could easily erase it all.  Since it is tmpfs there
> > is no need to umount it at all.  The point is to finish the
> > shutdown from a tmpfs so I can cleanly umount the aufs and the
> > filesystems under it including the file system on the host
> > machine or on the LiveUSB.
>
> My latest solution does pivot_root too for cleanliness reason, but it is
> actually unnecessary. You can still be on your original aufs root and take
> off the layer one by one - if you're careful - and have a clean unmount.
>
> >
> > >   Hehe. I like to say that initrd/initramfs is useless, [...]
> >
> > It is required for a live system.
>
> James, you won't convert Laurent :) I tried that before.
> I however is in the complete agreement with you. Initramfs is
> indispensable for this.
> Anyway, to each his own.
>
> ---
>
> If you really want to tell busybox init to quit - the simplest thing is to
> send SIGQUIT to it (kill -3 1). Once you do that, busybox init will execute
> all the ::shutdown scripts in /etc/inittab; and when done, it will exec to
> anything you put in ::restart. Whatever command you put in ::restart will
> run as pid 1 when all is said and done. This is however isn't useful for
> clean unmount because if you happen to use ntfs-3g, it will get killed too
> before it has the chance to unmount cleanly.
>
> cheers!
> James
>
> --
> James B <jamesbond3142 at gmail.com>
> _______________________________________________
> busybox mailing list
> busybox at busybox.net
> http://lists.busybox.net/mailman/listinfo/busybox
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.busybox.net/pipermail/busybox/attachments/20140811/4c8373b0/attachment-0001.html>