Re: network-namespace-aware nfsd

[Pavel Emelyanov <xemul@parallels.com>]

On 10/06/2011 05:11 PM, J. Bruce Fields wrote:
> On Thu, Oct 06, 2011 at 04:29:51PM +0400, Pavel Emelyanov wrote:
>>>> Also, do you think per-namespace version support is important?
>>>>
>>>
>>> Actually, yes, I do.
>>> As I see it, nfsd filesystem have to virtualized to provide flexible control for 
>>> server features. If so, then we need to virtualize program as well.
>>
>> ACK - per namespace version control is required as well.
>>
>> AFAIK it's performed via sysctl-s and this part (sysctls engine I mean) is already
>> namespaces aware, thus it will not be the hard part of the implementation :)
> 
> It's a special file in the nfsd filesystem.  But I assume that won't be
> a big deal either.

Well, yes, you're right :)

> By the way, I'm curious: as we do this virtualization step-by-step, is
> there any way for userspace to tell how far we've gotten?
> 
> So for example if you have a system that's configured to use some new
> namespace-based feature, and you boot it to an old kernel, is there some
> way for it to check at the start and say "sorry, this isn't going to
> work"?

M-m... I'd say - there's no automatic way for doing this. What we can (and probably
should) do is - audit the nfs/nfsd subsystems and mark places with
   if (ns != &init_net_ns)
          return -EOPNOTSUPP
and remove these parts eventually.

> --b.
> .
>