what should mountd do for NFSv4 only servers?

[Edward Tomasz Napierała]

On 1211T1923, Rick Macklem wrote:
> I recall an email discussion with Jason Mader w.r.t. what the behaviour of
> mountd(8) should be when an NFSv4 only server is being run.
> (I seem to have misplaced the email, so if I recall incorrectly, I apologize and hope
>  that Jason will correct me.;-)
> 
> mountd(8) serves the Mount protocol, which is related to NFSv2 and NFSv3, but has
> nothing to do with NFSv4.
> - At first glance, that would suggest that mountd(8) shouldn't serve Mount protocol
>   RPCs at all for a NFSv4 only server.
>   However, this would imply that "showmount -e" would not work.
>   I recall that Jason felt that "showmount -e" is useful, at least when run locally on
>   the server.
> 
> As such, how does having mountd(8) service Mount protocol requests only from localhost
> (127.0.0.1 and ::1) and only handle the Export RPC, when the NFS server is configured
> as NFSv4 only via vfs.nfsd.server_min_nfsvers == 4?
> 
> Any comments, concerns or other ideas please, rick

Another thing the mountd is useful for is the "-hosts" autofs map.  Restricting
mountd to the localhost would break it.