Major issues with nfsv4

[J David]

On Fri, Dec 11, 2020 at 6:28 PM Rick Macklem <rmacklem at uoguelph.ca> wrote:
> I am afraid I know nothing about nullfs and jails. I suspect it will be
> something related to when file descriptors in the NFS client mount
> get closed.

What does NFSv4 do differently than NFSv3 that might upset a low-level
consumer like nullfs?

> Well, NFSv3 is not going away any time soon, so if you don't need
> any of the additional features it offers...

If we did not want the additional features, we definitely would not be
attempting this.

> a user would have to run their own custom hacked
> userland NFS client. Although doable, I have never heard of it being done.

Alex beat me to libnfs.

What about this as a stopgap measure?

> How explosive would adding SO_REUSEADDR to the NFS client be?  It's
> not a full solution, but it would handle the TIME_WAIT side of the
> issue.

The kernel NFS networking code is confusing to me.  I can't even
figure out where/how NFSv4 binds a client socket to know if it's
possible.  (Pretty sure the code in sys/nfs/krpc_subr.c is not it.)

Thanks!