Re: [PATCH v15 14/26] nfs_common: add NFS LOCALIO auxiliary protocol enablement

[Mike Snitzer <snitzer@kernel.org>]

On Thu, Sep 05, 2024 at 03:24:06PM -0400, Anna Schumaker wrote:
> On Sat, Aug 31, 2024 at 6:38 PM Mike Snitzer <snitzer@kernel.org> wrote:
> >
> > fs/nfs_common/nfslocalio.c provides interfaces that enable an NFS
> > client to generate a nonce (single-use UUID) and associated
> > short-lived nfs_uuid_t struct, register it with nfs_common for
> > subsequent lookup and verification by the NFS server and if matched
> > the NFS server populates members in the nfs_uuid_t struct.
> >
> > nfs_common's nfs_uuids list is the basis for localio enablement, as
> > such it has members that point to nfsd memory for direct use by the
> > client (e.g. 'net' is the server's network namespace, through it the
> > client can access nn->nfsd_serv).
> >
> > This commit also provides the base nfs_uuid_t interfaces to allow
> > proper net namespace refcounting for the LOCALIO use case.
> >
> > CONFIG_NFS_LOCALIO controls the nfs_common, NFS server and NFS client
> > enablement for LOCALIO. If both NFS_FS=m and NFSD=m then
> > NFS_COMMON_LOCALIO_SUPPORT=m and nfs_localio.ko is built (and provides
> > nfs_common's LOCALIO support).
> >
> >   # lsmod | grep nfs_localio
> >   nfs_localio            12288  2 nfsd,nfs
> >   sunrpc                745472  35 nfs_localio,nfsd,auth_rpcgss,lockd,nfsv3,nfs
> >
> > Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> > Co-developed-by: NeilBrown <neilb@suse.de>
> > Signed-off-by: NeilBrown <neilb@suse.de>
> > ---
> >  fs/Kconfig                 |  23 ++++++++
> >  fs/nfs_common/Makefile     |   3 +
> >  fs/nfs_common/nfslocalio.c | 116 +++++++++++++++++++++++++++++++++++++
> >  include/linux/nfslocalio.h |  36 ++++++++++++
> >  4 files changed, 178 insertions(+)
> >  create mode 100644 fs/nfs_common/nfslocalio.c
> >  create mode 100644 include/linux/nfslocalio.h
> >
> > diff --git a/fs/Kconfig b/fs/Kconfig
> > index a46b0cbc4d8f..24d4e4b419d1 100644
> > --- a/fs/Kconfig
> > +++ b/fs/Kconfig
> > @@ -382,6 +382,29 @@ config NFS_COMMON
> >         depends on NFSD || NFS_FS || LOCKD
> >         default y
> >
> > +config NFS_COMMON_LOCALIO_SUPPORT
> > +       tristate
> > +       default n
> > +       default y if NFSD=y || NFS_FS=y
> > +       default m if NFSD=m && NFS_FS=m
> > +       select SUNRPC
> > +
> > +config NFS_LOCALIO
> > +       bool "NFS client and server support for LOCALIO auxiliary protocol"
> > +       depends on NFSD && NFS_FS
> > +       select NFS_COMMON_LOCALIO_SUPPORT
> > +       default n
> > +       help
> > +         Some NFS servers support an auxiliary NFS LOCALIO protocol
> > +         that is not an official part of the NFS protocol.
> > +
> > +         This option enables support for the LOCALIO protocol in the
> > +         kernel's NFS server and client. Enable this to permit local
> > +         NFS clients to bypass the network when issuing reads and
> > +         writes to the local NFS server.
> > +
> > +         If unsure, say N.
> > +
> 
> I'm wondering if it would make sense to create a fs/nfs_common/Kconfig
> file at some point (not as part of this patchset!) to hold this group
> of nfs_common options and to tidy up this section of the fs/Kconfig
> file.
> 
> Thoughts?
> Anna

Yes, I think that makes sense.

Mike