Re: pivotroot does not work with initramfs

[Olaf Hering <olh@suse.de>]

 On Sat, Nov 22, viro@parcelfarce.linux.theplanet.co.uk wrote:

> On Sat, Nov 22, 2003 at 09:48:54PM +0100, Olaf Hering wrote:
> > --- linuxppc-2.5_2.6.0-test9-bk.orig/fs/namespace.c     2003-10-08 03:52:02.000000000 +0200
> > +++ linuxppc-2.5_2.6.0-test9-bk/fs/namespace.c  2003-11-22 21:46:27.000000000 +0100
> > @@ -99,6 +99,7 @@ EXPORT_SYMBOL(lookup_mnt);
> >  static int check_mnt(struct vfsmount *mnt)
> >  {
> >         spin_lock(&vfsmount_lock);
> > +       if(mnt->mnt_parent->mnt_parent != mnt)
> >         while (mnt->mnt_parent != mnt)
> >                 mnt = mnt->mnt_parent;
> >         spin_unlock(&vfsmount_lock);
> 
> That's just plain ugly.  Could you explain what the hell are you trying to
> do?
> 
> If it's an attempt to make pivot_root move rootfs somewhere else - the above
> is nowhere near enough.  If it's something else, I wonder how the could
> that patch change anything.
> 
> *NOTE*: attempting to move rootfs away from root of mount tree is unsupported
> and for a good reason - it complicates logics big way and doesn't buy you
> anything that couldn't be done without it.

Ok, so pivot_root on rootfs is a bad idea. What I do now is to just look
for a /sbin/kinit binary (or something that is passed via kinit=) and run
this. And skip the call to mount_root() in prepare_namespace(). Seems to
work well.
kinit is supposed to find and mount the final root filesystem and mount
it on /root. Then return and let prepare_namespace() do the final work,
free the initmem and run the init process.

I dont know what you have in mind for 2.7, how much of the code will
disappear. We will hopefully use initramfs via cpio for 2.6 and get rid
of linuxrc. Lets see how far we get with that plan.

-- 
USB is for mice, FireWire is for men!

sUse lINUX ag, nÜRNBERG
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