Re: [PATCH 0/3] Add a mount option to support eager writes

[Trond Myklebust <trondmy@hammerspace.com>]

On Sat, 2021-02-13 at 09:19 -0500, Steve Dickson wrote:
> Hey!
> 
> On 2/12/21 4:49 PM, trondmy@kernel.org wrote:
> > From: Trond Myklebust <trond.myklebust@hammerspace.com>
> > 
> > The following patch series sets up a new mount option
> > 'writes=lazy/eager/wait'. The mount option basically controls how
> > the
> > write() system call works.
> > - writes=lazy is the default, and keeps the current behaviour
> > - writes=eager means we send off the write immediately as an
> > unstable
> >   write to the server.
> > - writes=wait means we send off the write as an unstable write, and
> > then
> >   wait for the reply.
> > 
> > The main motivator for this behaviour is that some applications
> > expect
> > write() to return ENOSPC. Setting writes=wait should satisfy those
> > applications without taking the full overhead of a synchronous
> > write.
> > 
> > writes=eager, on the other hand, can be useful for applications
> > such as
> > re-exporting NFS, since it would allow knfsd on the proxying server
> > to
> > immediately forward the writes to the original server.
> > 
> > Trond Myklebust (3):
> >   NFS: 'flags' field should be unsigned in struct nfs_server
> >   NFS: Add support for eager writes
> >   NFS: Add mount options supporting eager writes
> > 
> >  fs/nfs/file.c             | 19 +++++++++++++++++--
> >  fs/nfs/fs_context.c       | 33 +++++++++++++++++++++++++++++++++
> >  fs/nfs/write.c            | 17 ++++++++++++-----
> >  include/linux/nfs_fs_sb.h |  4 +++-
> >  4 files changed, 65 insertions(+), 8 deletions(-)
> > 
> Shouldn't something be added to the nfs(5) man page 
> as well as blurb added to /etc/nfsmount.conf file?
> 

Sure, but I'd like comments/consensus on the kernel bits first. 🙂

Cheers
  Trond

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com