Re: [PATCH 2/18] cleanups and bug fix in do_loopback()

[Ram Pai <linuxram@us.ibm.com>]

On Mon, 2005-11-07 at 22:59, Miklos Szeredi wrote:
> > - check_mnt() on the source of binding should've been unconditional from
> > the very beginning.  My fault - as far I could've trace it, that's an
> > old thinko made back in 2001.  Kudos to Miklos for spotting it...
> > Fixed.
> > - code cleaned up.
> 
> Can you please explain what purpose does this serve?
> 
> AFAICS check_mnt() was there to ensure that operations are done under
> the proper namespace semaphore.

> Next in the series the namespace semaphore is made global, which
> basically means, that most of the check_mnt() invocations become
> useless.
> The ones which as a side effect prevent grafting to a detached mount
> can be changed to check for (mnt->mnt_namespace == NULL) instead of
> check against current->namespace.
> 
> I see no other reason for wanting to prevent binds from detached
> mounts or other namespaces.  It has been discussed that it would be a
> good _controlled_ way to send/receive mounts from other namespace
> without adding any complexity.

AFAICT, the ability to bind across namespaces defeats the private-ness
property of per-process-namespaces. 

RP