Linux NFSv4 clients are getting (bad sequence-id error!)

[Rick Macklem]

Graham Allan wrote:
> For our part, the user whose code triggered the pathological behaviour
> on SL5 reran it on SL6 without incident - I still see lots of
> sequence-id errors in the logs, but nothing bad happened.
> 
> I'd still like to ask them to rerun again on SL5 to see if the "accept
> skipped seqid" patch had any effect, though I think we expect not. Maybe
> it would be nice if I could get set up to capture rolling tcpdumps of
> the nfs traffic before they run that though...
> 
> Graham
> 
> On 7/20/2015 10:26 PM, Ahmed Kamal wrote:
> > Hi folks,
> >
> > I've upgraded a test client to rhel6 today, and I'll keep an eye on it
> > to see what happens.
> >
> > During the process, I made the (I guess mistake) of zfs send | recv to a
> > locally attached usb disk for backup purposes .. long story short,
> > sharenfs property on the received filesystem was causing some nfs/mountd
> > errors in logs .. I wasn't too happy with what I got .. I destroyed the
> > backup datasets and the whole pool eventually .. and then rebooted the
> > whole nas box .. After reboot my logs are still flooded with
> >
> > Jul 21 05:12:36 nas kernel: nfsrv_cache_session: no session
> > Jul 21 05:13:07 nas last message repeated 7536 times
> > Jul 21 05:15:08 nas last message repeated 29664 times
> >
> > Not sure what that means .. or how it can be stopped .. Anyway, will
> > keep you posted on progress.
> 
Oh, I didn't see the part about "reboot" before. Unfortunately, it sounds like the
client isn't recovering after the session is lost. When the server reboots, the
client(s) will get NFS4ERR_BAD_SESSION errors back because the server reboot has
deleted all sessions. The NFS4ERR_BAD_SESSION should trigger state recovery on the client.
(It doesn't sound like the clients went into recovery, starting with a Create_session
 operation, but without a packet trace, I can't be sure?)

rick

> 
> --
> -------------------------------------------------------------------------
> Graham Allan - gta at umn.edu - allan at physics.umn.edu
> School of Physics and Astronomy - University of Minnesota
> -------------------------------------------------------------------------
> 
>