[Gluster-devel] regressions due to 64-bit ext4 directory cookies

[J. Bruce Fields]

On Thu, Mar 28, 2013 at 11:05:41AM -0700, Anand Avati wrote:
> On Thu, Mar 28, 2013 at 10:52 AM, Zach Brown <zab at redhat.com> wrote:
> 
> > On Thu, Mar 28, 2013 at 10:07:44AM -0400, Theodore Ts'o wrote:
> > > On Tue, Mar 26, 2013 at 10:48:14AM -0500, Eric Sandeen wrote:
> > > > > We don't have reached a conclusion so far, do we? What about the
> > > > > ioctl approach, but a bit differently? Would it work to specify the
> > > > > allowed upper bits for ext4 (for example 16 additional bit) and the
> > > > > remaining part for gluster? One of the mails had the calculation
> > > > > formula:
> > > >
> > > > I did throw together an ioctl patch last week, but I think Anand has a
> > new
> > > > approach he's trying out which won't require ext4 code changes.  I'll
> > let
> > > > him reply when he has a moment.  :)
> > >
> > > Any update about whether Gluster can address this without needing the
> > > ioctl patch?  Or should we push the ioctl patch into ext4 for the next
> > > merge window?
> >
> > They're testing a work-around:
> >
> >   http://review.gluster.org/#change,4711
> >
> > I'm not sure if they've decided that they're going to go with it, or
> > not.
> >
> 
> Jeff reported that the approach did not work in his testing. I haven't had
> a chance to look into the failure yet. Independent of the fix, it would
> certainly be good have the ioctl() support

The one advantage of your scheme is that it keeps more of the hash bits;
the chance of 31-bit cookie collisions is much higher.

> Samba could use it too, if it wanted.

It'd be useful to understand their situation.

--b.