NFS umount takes ages when no DNS available

[Robert Schulze]

Hi,

during maintainance work, I realized that an umount -h ip.ad.re.ss takes 
very long time when there is no nameserver reachable by the client (and 
server). All nfs configuration is done without hostnames, so I wonder 
why there is this delay (about 1 minute per mountpoint).

client: 8.1-RELEASE-p1/amd64
server: 8.2-STABLE/amd64

The hostname seems to be exchanged by client and server, this can be 
noticed by warnings like the following in /var/log/messages on the server:

rpc.statd: Failed to contact host client.foobar.net: RPC: Port mapper 
failure - RPC: Timed out

statd is running on the client, but bound to an interface with an ip 
address not matching the logged hostname.

Could NFS be tweaked in that way, that it does not use hostnames at all 
or at least will not provide hostnames on interfaces with don't carry 
the ip address the hostname matches to?

with kind regards,
Robert Schulze