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Date: Tue, 22 Mar 2016 17:46:53 -0400
Message-ID: <CAHQdGtSBamfGKNHDztCwE5JQcwwAiw66KJ0NgsTuSffCOBtF6Q@mail.gmail.com>
Subject: Re: [PATCH] nfs: add nfs IPv6 rdma6 mount option support
From: Trond Myklebust <trond.myklebust@primarydata.com>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: Anna Schumaker <Anna.Schumaker@netapp.com>,
        Shirley Ma <shirley.ma@oracle.com>,
        "J. Bruce Fields" <bfields@redhat.com>, Leon Romanovsky <leon@leon.nu>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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Sender: linux-nfs-owner@vger.kernel.org

On Tue, Mar 22, 2016 at 5:24 PM, Chuck Lever <chuck.lever@oracle.com> wrote:
>
>> On Mar 22, 2016, at 3:38 PM, Anna Schumaker <Anna.Schumaker@netapp.com> wrote:
>>
>> Hi Shirley,
>>
>> Sorry for the delay in looking at this patch.  Comments are below:
>>
>> On 03/16/2016 02:30 PM, Shirley Ma wrote:
>>> Add rdma6 option to support NFS/RDMA IPv6.
>>>
>>> Signed-off-by: Shirley Ma <shirley.ma@oracle.com>
>>
>> Can you add a little more to the patch description to describe when RDMA with IPv6 would be used?
>>
>>> ---
>>>
>>> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
>>> index f126828..62a55d0 100644
>>> --- a/fs/nfs/super.c
>>> +++ b/fs/nfs/super.c
>>> @@ -191,6 +191,7 @@ static const match_table_t nfs_mount_option_tokens = {
>>>
>>> enum {
>>>      Opt_xprt_udp, Opt_xprt_udp6, Opt_xprt_tcp, Opt_xprt_tcp6, Opt_xprt_rdma,
>>> +    Opt_xprt_rdma6,
>>>
>>>      Opt_xprt_err
>>> };
>>> @@ -201,6 +202,7 @@ static const match_table_t nfs_xprt_protocol_tokens = {
>>>      { Opt_xprt_tcp, "tcp" },
>>>      { Opt_xprt_tcp6, "tcp6" },
>>>      { Opt_xprt_rdma, "rdma" },
>>> +    { Opt_xprt_rdma6, "rdma6" },
>>>
>>>      { Opt_xprt_err, NULL }
>>> };
>>> @@ -1456,6 +1458,8 @@ static int nfs_parse_mount_options(char *raw,
>>>                              mnt->flags |= NFS_MOUNT_TCP;
>>>                              mnt->nfs_server.protocol = XPRT_TRANSPORT_TCP;
>>>                              break;
>>> +                    case Opt_xprt_rdma6:
>>> +                            protofamily = AF_INET6;
>>>                      case Opt_xprt_rdma:
>>>                              /* vector side protocols to TCP */
>>>                              mnt->flags |= NFS_MOUNT_TCP;
>>> @@ -1490,6 +1494,8 @@ static int nfs_parse_mount_options(char *raw,
>>>                      case Opt_xprt_tcp:
>>>                              mnt->mount_server.protocol = XPRT_TRANSPORT_TCP;
>>>                              break;
>>> +                    case Opt_xprt_rdma6:
>>> +                            mountfamily = AF_INET6;
>>>                      case Opt_xprt_rdma: /* not used for side protocols */
>>                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> Do we need to be setting mountfamily here?  The comment next to Opt_xprt_rdma makes it sound like this code doesn't apply to RDMA.
>
> I wondered this too.
>
> But what's going on is that for NFSv3 on RDMA, when IPv6 is
> used for the main protocol, IPv6 needs to be used for the
> mount protocol as well, even though it is going over TCP.

It causes nfs_mount_parse_options to immediately stop further parsing
and return '0' == error encountered. The mount is supposed to fail in
that case.