NFSv4 Questions

[Rick Macklem]

Andrey Simonenko wrote:
> On Sun, Apr 29, 2012 at 04:36:03PM -0400, Rick Macklem wrote:
> >
> > Also, be sure to check "man nfsv4" and maybe reference it (it is
> > currently
> > in the See Also list, but that might not be strong enough).
> 
> There is another question not explained in documentation (I could not
> find the answer at least). Currently NFSv3 client uses reserved port
> for NFS mounts and uses non reserved port if "noresvport" is
> specified.
> NFSv4 client always uses non reserved port, ignoring the "resvport"
> option in the mount_nfs command.
> 
> Such behaviour of NFS client was introduced in 1.18 version of
> fs/nfsclient/nfs_clvfsops.c [1], where the "resvport" flag is cleared
> for NFSv4 mounts.
> 
> Why does "reserved port logic" differ in NFSv3 and NFSv4 clients?
> 
It is my understanding that NFSv4 servers are not supposed to require
a "reserved" port#. However, at a quick glance, I can't find that stated
in RFC 3530. (It may be implied by the fact that NFSv4 uses a "user" based
security model and not a "host" based one.)

As such, the client should never need to "waste" a reserved port# on a NFSv4
connection.

rick

> > > If I may, perhaps a switch in /etc/rc.conf:
> > > nfsv4_only="YES"
> > >
> > I might call it nfsv4_server_only, but sounds like a good
> > suggestion.
> >
> > > This would set the -nfsv4-only switch you mention for mountd, and
> > > it
> > > would set vfs.nfsd.server_min_nfsvers=4
> > >
> > It could also be used by /etc/rc.d/mountd to indicate "don't force
> > rpcbind".
> >
> 
> I'm sure that you know all these, but let me add some comments.
> 
> 1. Using server_min_nfsvers and server_max_nfsvers are global settings
> and do not allow to make one file system NFSv2/3/4 exported and
> another
> one NFSv4 exported only for example.
> 
> 2. MOUNT protocol is not used only for MNT/UMNT/UMNTALL requests from
> NFSv2/3 clients. As I know some automounters use MOUNT EXPORT requests
> to get information about exported file systems. So, MOUNT protocol
> can be usefull for somebody who uses NFSv4 only.
> 
> Both items have something common. There should be options that enable/
> disables NFSv2, NFSv3 and/or NFSv4 per address specification and/or
> per
> file system. And there should be the option that allows to disable the
> MOUNT protocol entirely, some of its versions or some of its
> netconfigs
> (some of visible netconfigs that can be used by the MOUNT protocol).
> 
> [1]
> http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/fs/nfsclient/nfs_clvfsops.c.diff?r1=1.17;r2=1.18