Re: nfs + Reiser4

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Wed, 2010-04-07 at 15:20 -0400, J. Bruce Fields wrote: 
> On Wed, Apr 07, 2010 at 02:59:36PM -0400, Chuck Lever wrote:
> > On 04/07/2010 02:51 PM, J. Bruce Fields wrote:
> >> On Wed, Apr 07, 2010 at 02:44:01PM -0400, Chuck Lever wrote:
> >>> On 04/07/2010 01:34 PM, J. Bruce Fields wrote:
> >>>> On Tue, Apr 06, 2010 at 07:52:21PM +0200, gg-B3jsHfKwJfLR7s880joybQ@public.gmane.org wrote:
> >>>>> I am having serious headaches using nfs between a reiser4 server and arm
> >>>>> client.
> >>>>> Both on 2.6.29 vintage kernels.
> >>>>>
> >>>>> Files are constantly getting out of sync.
> >>>>>
> >>>>> Example :
> >>>>>
> >>>>> boot ARM via nfs
> >>>>> edit lighttpd.conf on ARM
> >>>>> check edit is visible on server. OK
> >>>>>
> >>>>> reboot ARM
> >>>>> check file : reverted to an earlier state.
> >>>>> check server: edited version still showing.
> >>>>
> >>>> So, on a freshly booted NFS client, you're opening and reading a file
> >>>> and seeing file data that isn't even on the NFS server any more?
> >>>>
> >>>> That's beyond bizarre.  Do you have a reliable way to reproduce the
> >>>> problem?
> >>>
> >>> Could be XID replay.
> >>
> >> I'm not following you.  You're thinking of a read request after the
> >> reboot that unluckily reuses an old XID and gets stale data from the
> >> servers reply cache?  Or something else?
> >
> > Nothing unlucky about it.  Just after a boot, if the client  
> > implementation isn't careful about choosing an initial XID, (eg it  
> > always starts with a psuedorandom number but uses the same seed every  
> > time), it will hit the server's replay cache.
> 
> Hm, OK.
> 
> > This can be quite reproducible for NFSROOT and a quiescent server.
> 
> The Linux server doesn't cache READ results as far as I can tell.
> 
> --b.

Is he perhaps using the Debian unfsd or some other user space nfs
server?

Cheers
  Trond