Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:3996 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751660Ab0ARWdm (ORCPT ); Mon, 18 Jan 2010 17:33:42 -0500 Date: Mon, 18 Jan 2010 17:33:36 -0500 From: Jeff Layton To: Chuck Lever Cc: steved@redhat.com, linux-nfs@vger.kernel.org Subject: Re: enabling IPv6 Message-ID: <20100118173336.18a8323b@tlielax.poochiereds.net> In-Reply-To: <0FE403CA-9487-485C-9949-FEC072EC2314@oracle.com> References: <20100118144746.1e05865e@tlielax.poochiereds.net> <0FE403CA-9487-485C-9949-FEC072EC2314@oracle.com> Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Mon, 18 Jan 2010 16:28:39 -0500 Chuck Lever wrote: > > On Jan 18, 2010, at 2:47 PM, Jeff Layton wrote: > > > With the commit of the statd patches over the weekend, we're now > > positioned to be able to ship IPv6-enabled nfs-utils in distros. There > > is a potential snag though... > > > > Consider this situation: > > > > Admin has a Linux server set up. Server has both IPv4 and IPv6 addrs. > > Both addresses are in DNS. > > > > Without an IPv6-enabled nfs-utils, he mounts via IPv4 and all works > > fine. Now with an IPv6 enabled nfs-utils, mount.nfs prefers the IPv6 > > addr and the mount fails (or hangs for a long time and then fails, if > > it's using NFSv4)... > > Why should it fail? > Because Linux NFS servers that work over IPv6 pretty much don't exist yet. > > While I don't really like it, I think we may need to consider making > > mount.nfs prefer IPv4 addrs when it can resolve a hostname to both v4 > > and v6. Otherwise, we run the risk of breaking an awful lot of working > > setups... > > Isn't that what "proto=udp" vs. "proto=udp6" is for? > Yes. But that assumes that the admin will know to use that. As it stands now, they'll have to do a bit of investigation to figure out why the mount failed and then figure out how to fix it. Obviously, that's less ideal than a solution that leaves setups working that are working today. I don't think we ought to put the onus on users to add extra mount options to stay working. -- Jeff Layton