Re: [NLM] fcntl(F_SETLKW) yields -ENOLCK when grace period expires.

[Frank van Maarseveen <frankvm@frankvm.com>]

On Thu, Aug 04, 2011 at 01:10:20PM -0400, Trond Myklebust wrote:
> On Thu, 2011-08-04 at 12:49 -0400, J. Bruce Fields wrote: 
> > On Thu, Aug 04, 2011 at 06:43:13PM +0200, Frank van Maarseveen wrote:
> > > On Thu, Aug 04, 2011 at 12:34:52PM -0400, J. Bruce Fields wrote:
> > > > On Thu, Aug 04, 2011 at 12:30:19PM +0200, Frank van Maarseveen wrote:
> > > > > Both client- and server run 2.6.39.3, NFSv3 over UDP (without the
> > > > > relock_filesystem patch proposed earlier).
> > > > > 
> > > > > A second client has an exclusive lock on a file on the server. The
> > > > > client under test calls fcntl(F_SETLKW) to wait for the same exclusive
> > > > > lock. Wireshark sees NLM V4 LOCK calls resulting in NLM_BLOCKED.
> > > > > 
> > > > > Next the server is rebooted. The second client recovers the lock
> > > > > correctly. The client under test now receives NLM_DENIED_GRACE_PERIOD for
> > > > > every NLM V4 LOCK request resulting from the waiting fcntl(F_SETLKW). When
> > > > > this changes to NLM_BLOCKED after grace period expiration the fcntl
> > > > > returns -ENOLCK ("No locks available.") instead of continuing to wait.
> > > > 
> > > > So that sounds like a client bug, and correct behavior from the server
> > > > (assuming the second client was still holding the lock throughout).
> > > 
> > > yes.
> 
> Is the client actually asking for a blocking lock after the grace period
> expires?

yes, according to my interpretation of that of wireshark, see reply to Bruce.

-- 
Frank