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Subject: Re: Support for VRF in NFS?
To:     Ben Greear <greearb@candelatech.com>,
        "J. Bruce Fields" <bfields@fieldses.org>
Cc:     "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        David Windsor <dwindsor@redhat.com>
References: <b608aeda-358d-18c9-ebcd-753b698580e9@candelatech.com>
 <20181108011429.GC30776@fieldses.org>
 <efe334ad-4905-fc24-1b36-3c4129b72888@candelatech.com>
 <20181108153136.GA4947@fieldses.org>
 <90f8e9ba-3953-e2d1-56f4-421a4991cef8@candelatech.com>
From:   Steven Whitehouse <swhiteho@redhat.com>
Message-ID: <74f0a2e8-f631-8d8d-5b98-8248dadf5aa6@redhat.com>
Date:   Fri, 9 Nov 2018 09:59:04 +0000
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Hi,


On 08/11/18 16:35, Ben Greear wrote:
>
>
> On 11/08/2018 07:31 AM, J. Bruce Fields wrote:
>> On Wed, Nov 07, 2018 at 09:08:16PM -0800, Ben Greear wrote:
>>>
>>>
>>> On 11/07/2018 05:14 PM, J. Bruce Fields wrote:
>>>> On Tue, Nov 06, 2018 at 01:03:54PM -0800, Ben Greear wrote:
>>>>> Hello,
>>>>>
>>>>> I made a stab at implementing VRF support in NFS, but it appears
>>>>> fairly complicated and I ended up reverting my changes....
>>>>>
>>>>> Is anyone working on this?
>>>>>
>>>>> And, if not, if anyone would like to be sponsored to work on this, 
>>>>> please
>>>>> let me know.
>>>>
>>>> Um, sorry--what's VRF?
>>>
>>> Virtual Router logic.? It is sort of like network stack containers,
>>> and has been solid and fully featured in the kernel since 4.16 or so.
>>>
>>> In the end, you effectively need to call the logic that SO_BINDTODEVICE
>>> calls on the socket before binding to an IP.
>>>
>>> The NFS and RPC logic is a giant tangled mess to my eyes, so
>>> hoping I could bribe someone else to do it :)
>>
>> So it's not enough to support network namespaces?
>>
>> What's your motivation for this?
>
> Network namespaces are difficult to uses for lots of use cases, and 
> thus VRF
> was born.
>
> My own motivation is that it allows me to make hundreds or thousands
> of individual NFS mounts from local mac-vlan (or other 
> virtual/physical interfaces),
> for testing purposes.
>
> Similar to my patch set that binds to local IP address, which gives 
> similar feature
> set for non-VRF configurations.? These bind-local-IP patches are not 
> upstream and were rejected in
> the past as un-wanted.? I'm hoping VRF support would be more acceptable.
>
> Thanks,
> Ben
>

For similar reasons David Windsor has been looking at some extensions 
for DLM along these lines. Improving our ability to test seems to me 
like it should be a good thing to do - in both cases. Likewise VRF 
support seems also like it should be useful in a number of contexts.

Do you have a reference to your past work? I think it would be 
interesting to get some discussion going here - maybe it would be 
possible to have some common approach between kernel-side socket users, 
and/or bounce some ideas around,

Steve.