Re: [PATCH 0/6 v7] overlay filesystem - request for inclusion

From: Al Viro
Date: Tue Mar 22 2011 - 15:00:17 EST


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@xxxxxxxxxxxxxxxxxx> 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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