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From: Cedric Blancher <cedric.blancher@gmail.com>
Date: Wed, 24 Jan 2024 15:04:44 +0100
Message-ID: <CALXu0UfQzHA7MZ76ETRbMksSqBsP8zc+cf9EBLi80BgqNh1o6g@mail.gmail.com>
Subject: Re: Change "hostname" to "hostport" in text-based mountd downcall Re:
 BUG in exports(5), no example for refer= Re: Examples for refer= in /etc/exports?
To: Steve Dickson <steved@redhat.com>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>, Martin Wege <martin.l.wege@gmail.com>, 
	Chuck Lever III <chuck.lever@oracle.com>, Roland Mainz <roland.mainz@nrubsig.org>
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?

On Sun, 19 Nov 2023 at 18:17, Cedric Blancher <cedric.blancher@gmail.com> w=
rote:
>
> On Mon, 13 Nov 2023 at 16:48, Steve Dickson <steved@redhat.com> wrote:
> >
> > Hello Ced,
> >
> > On 11/12/23 8:01 PM, Cedric Blancher wrote:
> > > On Fri, 10 Nov 2023 at 20:17, Chuck Lever III <chuck.lever@oracle.com=
> wrote:
> > >>
> > >>
> > >>
> > >>> On Nov 10, 2023, at 3:30 AM, Martin Wege <martin.l.wege@gmail.com> =
wrote:
> > >>>
> > >>> On Fri, Nov 10, 2023 at 3:20=E2=80=AFAM Chuck Lever III <chuck.leve=
r@oracle.com> wrote:
> > >>>>
> > >>>>> On Nov 9, 2023, at 7:47 PM, Cedric Blancher <cedric.blancher@gmai=
l.com> wrote:
> > >>>>>
> > >>>>> On Fri, 10 Nov 2023 at 01:37, Chuck Lever III <chuck.lever@oracle=
.com> wrote:
> > >>>>>>
> > >>>>>>> On Nov 9, 2023, at 7:05 PM, Cedric Blancher <cedric.blancher@gm=
ail.com> wrote:
> > >>>>>>>
> > >>>>>>> On Thu, 2 Nov 2023 at 10:51, Cedric Blancher <cedric.blancher@g=
mail.com> wrote:
> > >>>>>>>>
> > >>>>>>>> Good morning!
> > >>>>>>>>
> > >>>>>>>> Does anyone have examples of how to use the refer=3D option in=
 /etc/exports?
> > >>>>>>>
> > >>>>>>> Short answer:
> > >>>>>>> To redirect an NFS mount from local machine /ref/baguette to
> > >>>>>>> /export/home/baguette on host 134.49.22.111 add this to Linux
> > >>>>>>> /etc/exports:
> > >>>>>>>
> > >>>>>>> /ref *(no_root_squash,refer=3D/export/home@134.49.22.111)
> > >>>>>>>
> > >>>>>>> This is basically an exports(5) manpage bug, which does not pro=
vide
> > >>>>>>> ANY examples.
> > >>>>>>
> > >>>>>> That's because setting up a referral this way is deprecated.
> > >>>>>
> > >>>>> Why did you do that?
> > >>>>
> > >>>> The nfsref command on Linux matches the same command on Solaris.
> > >>>>
> > >>>> nfsref was added years ago to manage junctions, as part of FedFS.
> > >>>> The "refer=3D" export option can't do that...
> > >>>
> > >>> Where in the kernel is the code for the refer=3D option? I'd like t=
o get
> > >>> some of my students to contribute support for custom NFS ports.
> > >>
> > >> IIRC supporting ports is one thing we can't do right now because
> > >> the mountd downcall interface is text-based, and its parser can
> > >> barely handle "refer=3D", let alone specifying a port.
> > >
> > > I had a chat this weekend with Roland Mainz (who works on the NFSv4
> > > driver for Windows these days):
> > > ...
> > > That is the old mistake to think that "hostname" and "port" are
> > > separate entities. We had this kind of debate at SUN/MPK17 several
> > > times. Host and TCP port are the "location of the server", and they
> > > are inseparable.
> > > ...
> > > The RFCs even help out with that one, for example RFC1738 (URL RFC)
> > > defines a "hostport" in Page 18.
> > > And that's what I actually did for ms-nfs41-client: NIH&Institute
> > > Pasteur needed custom TCP server ports, and I implemented this by
> > > changing the communication of nfs41_driver.sys (kernel) to userland
> > > NFSv4 client daemon (nfsd_debug.exe) from "hostname" to "hostport",
> > > and added the port number in the UNC, so Windows always uses (and
> > > remembers!) the port number together with the hostname.
> > > Or easier: I changed "hostname" to "hostport" to embed the port numbe=
r
> > > in the up-/downcalls for mount requests - and that is what the Linux
> > > people can use too.
> > > ...
> > >
> > >> Our plan is to replace the mountd downcall with a netlink protocol
> > >> that Lorenzo is working on, and then it would be very straightforwar=
d
> > >> to add a port to each target location. But getting to a mature
> > >> netlink implementation will take a while.
> > >
> > > Yeah, instead of waiting for NetLink you could implement Roland's
> > > suggestion, and change "hostname" to "hostport" in your test-based
> > > mount protocol, and technically everywhere else, like /proc/mounts an=
d
> > > the /sbin/mount output.
> > > So instead of:
> > > mount -t nfs -o port=3D4444 10.10.0.10:/backups /var/backups
> > > you could use
> > > mount -t nfs 10.10.0.10@4444:/backups /var/backups
> > >
> > > The same applies to refer=3D - just change from "hostname" to
> > > "hostport", and the text-based mountd downcall can stay the same (e.g=
.
> > > so "foobarhost" changes to "foobarhost@444" in the mountd download.)
> > My suggestion is you and Roland attend the next Bakeathon, this
> > spring, which will have remote access for testing and
> > talk about this on one of @2pm talks.
>
> Where is the bakeathon hosted? San Francisco?
>
> Ced
> --
> Cedric Blancher <cedric.blancher@gmail.com>
> [https://plus.google.com/u/0/+CedricBlancher/]
> Institute Pasteur


--=20
Cedric Blancher <cedric.blancher@gmail.com>
[https://plus.google.com/u/0/+CedricBlancher/]
Institute Pasteur