knfsd: Add source address to sunrpc svc errors

This patch adds the address of the client that caused an error in
sunrpc/svc.c so that you get errors that look like:

svc: 192.168.66.28, port=709: unknown version (3 for prog 100003, nfsd)

I've seen machines which get bunches of unknown version or similar
errors from time to time, and while the recent patch to add the service
helps to find which service has the wrong version it doesn't help find
the potentially bad client.

The patch is against a checkout of Linus's git tree made on 2007-08-24.

One observation is that the svc_print_addr function prints to a buffer
which in this case makes life a little more complex; it just feels as if
there must be lots of places that print a connection address - is there
a better function to use anywhere?

I think actually there are a few places with semi duplicated code; e.g.
one_sock_name switches on the address family but only currently has
IPV4; I wonder how many other places are similar.

Signed-off-by: Dave Gilbert <linux@treblig.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Acked-by: Neil Brown <neilb@suse.de>