Date: Thu, 14 Feb 2013 16:47:44 -0500
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Anand Avati <anand.avati@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
        Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>, sandeen@redhat.com,
        linux-nfs@vger.kernel.org, linux-ext4@vger.kernel.org,
        gluster-devel@nongnu.org
Subject: Re: [Gluster-devel] regressions due to 64-bit ext4 directory cookies
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On Wed, Feb 13, 2013 at 04:05:01PM -0800, Anand Avati wrote:
> On Wed, Feb 13, 2013 at 3:44 PM, Theodore Ts'o <tytso@mit.edu> wrote:
> >
> > I suspect this would seriously screw over Gluster, though, and this
> > wouldn't be a solution for NFSv3, since NFS needs long-lived directory
> > cookies, and not the short-lived cookies which is all POSIX/SuSv3
> > guarantees.
> >
> 
> Actually this would work just fine with Gluster. Except in the case of
> gluster-NFS, the native client is only acting like a router/proxy of
> syscalls to the backend system. A directory opened by an application will
> have a matching directory fd opened on ext4, and readdir from an app will
> be translated into readdir on the matching fd on ext4. So the
> app-on-glusterfs and glusterfsd-on-ext4 are essentially "moving in tandem".
> As long as the offs^H^H^H^H cookies do not overflow in the transformation,
> Gluster would not have a problem.
> 
> However Gluster-NFS (and NFS in general, too) will break, as we
> opendir/closedir potentially on every request.

Yes.  And, of course, NFS cookies live forever--we have no idea when a
client will hand one back to us and expect us to do something with it.

--b.