linux-kernel - Re: [PATCH 0/6 v7] overlay filesystem

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Date:	Tue, 22 Mar 2011 19:00:02 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, apw@...onical.com, nbd@...nwrt.org,
	neilb@...e.de
Subject: Re: [PATCH 0/6 v7] overlay filesystem - request for inclusion

On Tue, Mar 22, 2011 at 07:58:17PM +0100, Miklos Szeredi wrote:
> On Tue, 22 Mar 2011, Linus Torvalds wrote:
> > On Tue, Mar 22, 2011 at 11:39 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> > >
> > > Locking analysis would be really nice; AFAICS, it violates locking order
> > > when called from e.g. ->setattr()
> 
> Locking order is always:
> 
> -> overlayfs locks
>    -> upper fs locks
>    -> lower fs locks
> 
> So it's really pretty simple and easy to validate.

In which *order* on the upper fs?

> Protection is exactly as for userspace callers.  AFAICT.

Pardon?  You traverse the chain of ancestors; fine, but who says it stays
anywhere near being relevant as you go?
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