Re: possible client stale filehandle bug?

[Garrick Staples <garrick@usc.edu>]

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On Tue, Jan 25, 2005 at 10:06:27PM -0800, Trond Myklebust alleged:
> ty den 25.01.2005 Klokka 09:39 (-0800) skreiv Garrick Staples:
> > Hi all,
> >    I have lots of storage in a large Solaris samfs environment that is NFS
> > shared to a large number of Solaris and RHEL3 clients.  Under some conditions,
> > linux apps have been getting stale filehandles during the normal course of
> > their activity.  Various file handling syscalls like read() or open() might
> > error.  Lots of renames and setattrs calls seem to trigger the problem.  
> > 'ci' and 'cvs commit' are particularly good at this.
> 
> ESTALE is usually a sign that someone is deleting a file on the server
> that is in use by the client. It is a sign that you are doing something
> that violates the caching rules of NFS.

Nothing of the kind is happening here.  I've tested this a thousand times over
the last few days trying to find a solution.  In this case, Sun's samfs
filesystem is definitely at fault and doing the wrong thing.  Backline
engineers at Sun confirm this and are working on a fix.  

The reason for _this_ email isn't because of the ESTALEs, it's regarding the
handling of the ESTALEs.  Right now I need the Solaris client behaviour to
deal with this particular buggy server.

Incidentally, 2.6.10 never has a problem.  It's behaviour never creates ESTALEs in
the first place.

 
> > It seems that the Solaris clients never report any such errors, only the Linux
> > clients.  However, watching 'snoop' on the Solaris NFS server, I see that it IS
> > returning stale file handles to both OSes, but Solaris clients seem to retry
> > the request several times; and the Linux clients immediately pass the error up
> > to the application.
> > 
> > Is there some condition that the 2.4 kernel is handling incorrectly?
> 
> I do not believe that Solaris redrives ESTALE on read, but they may do
> it on open(). Linux does not redrive either case. See the many
> discussions in the NFS list archives for why.

Did you look at the 'snoop' bits in the previous email?  During that time, the
process on the Solaris client is hanging in a write() call.

I'd be very happy to see any patches lieing around that might do this
behaviour.  It would get me through the short term until Sun fixes this bug in
samfs.

-- 
Garrick Staples, Linux/HPCC Administrator
University of Southern California

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