Re: [PATCH 6/6] nfs: disable leases over NFS

["J. Bruce Fields" <bfields@fieldses.org>]

On Sat, Jun 30, 2007 at 10:25:16AM +0100, Christoph Hellwig wrote:
> On Fri, Jun 29, 2007 at 03:21:30PM -0400, J. Bruce Fields wrote:
> > From: J. Bruce Fields <bfields@citi.umich.edu>
> > 
> > As Peter Staubach says elsewhere
> > (http://marc.info/?l=linux-kernel&m=118113649526444&w=2):
> > 
> > > The problem is that some file system such as NFSv2 and NFSv3 do
> > > not have sufficient support to be able to support leases correctly.
> > > In particular for these two file systems, there is no over the wire
> > > protocol support.
> > >
> > > Currently, these two file systems fail the fcntl(F_SETLEASE) call
> > > accidentally, due to a reference counting difference.  These file
> > > systems should fail more consciously, with a proper error to
> > > indicate that the call is invalid for them.
> > 
> > Define an nfs setlease method that just returns -EOPNOTSUPP.
> > 
> > If someone can demonstrate a real need, perhaps we could reenable
> > them in the presence of the "nolock" mount option.
> 
> I'm not a big fan of default methods that do the wrong thing instead
> of just missing functionality.  Would you mind just returning
> -EOPNOTSUPP if ->setlease is not implemented and add it to all
> the local filesystems while all the network/distributed filesystems
> should not have it, not just nfs.

OK, I think that may make sense, but... wow does linux ever have a lot
of obscure filesystems.  This might take me a little longer.

--b.