[NFS-Ganesha-Devel] Re: Better interop for NFS/SMB file share mode/reservation

[Frank Filz]

> From: 'J. Bruce Fields' [mailto:bfields at fieldses.org]
> Sent: Friday, March 8, 2019 1:38 PM
> To: Frank Filz <ffilzlnx at mindspring.com>
> Cc: 'linux-fsdevel' <linux-fsdevel at vger.kernel.org>;
> Volker.Lendecke at sernet.de; samba-technical at lists.samba.org; 'Jeremy Allison'
> <jra at samba.org>; 'Linux NFS Mailing List' <linux-nfs at vger.kernel.org>; 'Jeff
> Layton' <jlayton at kernel.org>; 'Amir Goldstein' <amir73il at gmail.com>;
> devel at lists.nfs-ganesha.org; 'Ralph Boehme' <slow at samba.org>
> Subject: [NFS-Ganesha-Devel] Re: Better interop for NFS/SMB file share
> mode/reservation
> 
> On Wed, Mar 06, 2019 at 07:37:00AM -0800, Frank Filz wrote:
> > > On Wed, Mar 06, 2019 at 09:09:21AM +0200, Amir Goldstein wrote:
> > > > On Tue, Mar 5, 2019 at 11:48 PM J. Bruce Fields
> > > > <bfields at fieldses.org> wrote:
> > > > >
> > > > > On Thu, Feb 14, 2019 at 04:06:52PM -0500, J. Bruce Fields wrote:
> > > > > > After this:
> > > > > >
> > > > > >       https://marc.info/?l=linux-nfs&m=154966239918297&w=2
> > > > > >
> > > > > > delegations would no longer conflict with opens from the same
> > > > > > tgid.  So if your threads all run in the same process and
> > > > > > you're willing to manage conflicts among your own clients,
> > > > > > that should still allow you to do multiple opens of the same
> > > > > > file without giving up your
> > > lease/delegation.
> > > > > >
> > > > > > I'd be curious to know whether that works with Samba's design.
> > > > >
> > > > > Any idea whether that would work?
> > > > >
> > > > > (Easy?  Impossible?  Possible, but realistically the changes
> > > > > required to Samba would be painful enough that it'd be unlikely
> > > > > to get done?)
> > > > >
> > > >
> > > > [CC Ralph Boehme]
> > > >
> > > > I am not a samba team member, but seems to me that your proposal
> > > > fits samba design like a glove. With one smbd process per client
> > > > connection, with your proposal, opens (for read) from same smbd
> > > > process will not break the shared read lease from same client, so
> > > > oplocks level II could be implemented using kernel oplocks (new
> > > > flavor).
> > >
> > > OK.  So I wonder about Ganesha.  I'm not sure, but I *think* it's
> > > like knfsd in that it has a bunch of worker threads that can each
> > > take rpc's from any client.  I don't remember if they're actually
> > > threads or processes.
> >
> > Ganesha does use worker threads
> 
> And they're all part of one process?

Sorry, should have specified, yes, Ganesha runs a single multi-threaded process.

> > however, one thing that may be an
> > advantage here, or at least can be leveraged, is that Ganesha attaches
> > a single file descriptor to each stateid. As long as the I/O requests
> > come using the stateid, that file descriptor will be used.
> >
> > We have some work completed and more in progress on delegations, and
> > if there becomes a new kernel oplock available, we could definitely
> > use it. On the other hand, FSAL_VFS which is the FSAL used with kernel
> > file systems does not support delegations...
> >
> > The (distributed) file systems we support delegations on have use
> > space libraries (which Samba should also be using?) that implement the
> > delegation primitives.
> 
> Is there anyone working on delegation support for FSAL_VFS?  If it's not getting
> much attention then maybe Samba is the only real user for the forseeable
> future.

As far as I know, no one is working on delegations for FSAL_VFS. A good interface would make it something that might be used if it then became easy to implement delegations. FSAL_VFS is convenient for verifying some of the protocol and meta-data caching features of Ganesha.

Frank