Comment # 3 on bug 986395 from Neil Brown

I've looked into this a bit more.

I think that using a temporary address to connect to the server is a valid
thing to do.  As Marius clarified, that address will remain valid as long as
the connection to the server persists.  If the client needs to disconnect and
reconnect it should get a new client address.

However for NFSv4.0 the client needs to tell the server how the server can
call-back to the client for various state management functions.  If a temporary
address is provided for that, the server may find that it cannot contact the
client.
This is only needed for NFSv4.0.  NFSv4.1 and later use the connection from
client to server as a back-channel so the server never contacts the client
directly.

So: I think that if the client uses NFSv4.1, the temporary address should not
cause a problem.  So mount with "-o vers=4.1" - assuming the server supports
that.

If v4.0 must be used, then you can specify the preferred client address with
the "clientaddr mount option. 
i.e. "mount -t nfs -o clientaddr=xx:xx:xx::xx ....."

If no clientaddr option is given, mount.nfs will choose one itself.  It would
be best if mount.nfs chose a non-temporary address and I will look into that.
However I'd like to be sure that I'm chasing the right problem.

So please:
 1/ explain exactly why you think it currently doesn't work - what symptoms are
there?
 2/ If possible, test with "-o vers=4.1" and see if the symptoms persist.
 3/ Also test with "-o clientaddr=......" and see if the symptoms persist.

Thanks.