From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 7/9] ovl: Introduce read/write barriers around metacopy
 flag update
Date: Mon, 16 Oct 2017 09:24:53 -0400
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To: Amir Goldstein <amir73il@gmail.com>
Cc: overlayfs <linux-unionfs@vger.kernel.org>, Miklos Szeredi <miklos@szeredi.hu>, "Eric W. Biederman" <ebiederm@xmission.com>

On Sat, Oct 14, 2017 at 09:05:17AM +0300, Amir Goldstein wrote:

[..]
> > When I read memory-barrier.txt, it seems to suggest that RELEASE can let
> > instructions outside critical region sneak into critical region. If that's
> > the case, actually clearing of metaflag can happen before xattr actually
> > got removed. Though I can't think what will go wrong in that case.
> 
> clear_bit takes a spinlock so I *think* clearing of flag cannot sneak
> before removing xattr.

Which spinlock does clear_bit take? Are you referring to ovl_inode->lock mutex?

Vivek