tree 98ab0d6619c21fadae3bf9c64aa77e8574019323
parent 9130b8dbc6ac20f2dc5846e1647f5b60eafab6e3
author NeilBrown <neilb@suse.com> 1470291868 +1000
committer Trond Myklebust <trond.myklebust@primarydata.com> 1470410999 -0400

SUNRPC: disable the use of IPv6 temporary addresses.

If the net.ipv6.conf.*.use_temp_addr sysctl is set to '2',
then TCP connections over IPv6 will prefer a 'private' source
address.
These eventually expire and become invalid, typically after a week,
but the time is configurable.

When the local address becomes invalid the client will not be able to
receive replies from the server.  Eventually the connection will timeout
or break and a new connection will be established, but this can take
half an hour (typically TCP connection break time).

RFC 4941, which describes private IPv6 addresses, acknowledges that some
applications might not work well with them and that the application may
explicitly a request non-temporary (i.e. "public") address.

I believe this is correct for SUNRPC clients.  Without this change, a
client will occasionally experience a long delay if private addresses
have been enabled.

The privacy offered by private addresses is of little value for an NFS
server which requires client authentication.

For NFSv3 this will often not be a problem because idle connections are
closed after 5 minutes.  For NFSv4 connections never go idle due to the
period RENEW (or equivalent) request.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>