Message-ID: <4F688655.1090703@rath.org>
Date: Tue, 20 Mar 2012 09:29:57 -0400
From: Nikolaus Rath <Nikolaus@rath.org>
MIME-Version: 1.0
To: Rick Macklem <rmacklem@uoguelph.ca>
CC: linux-nfs@vger.kernel.org, nfsv4@ietf.org,
        "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [nfsv4] NFS4 over VPN hangs when connecting > 2 clients
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In-Reply-To: <716104306.1267694.1332195933869.JavaMail.root@erie.cs.uoguelph.ca>
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On 03/19/2012 06:25 PM, Rick Macklem wrote:
> Nikolaus Rath wrote:
>> On 03/19/2012 02:39 PM, J. Bruce Fields wrote:
>>> On Mon, Mar 19, 2012 at 02:29:46PM -0400, Chuck Lever wrote:
>>>>
>>>> On Mar 19, 2012, at 2:27 PM, J. Bruce Fields wrote:
>>>>
>>>>> On Mon, Mar 19, 2012 at 01:47:14PM -0400, Chuck Lever wrote:
>>>>>>
>>>>>> On Mar 19, 2012, at 1:36 PM, J. Bruce Fields wrote:
>>>>>>> Well, sure, but all I'm proposing here is returning
>>>>>>> NFS4ERR_INUSE in the
>>>>>>> case where we get setclientid's with the same client-provided
>>>>>>> id.
>>>>>>> There'd be no change of behavior in the case of multiple clients
>>>>>>> sharing
>>>>>>> an IP (which is fine, of course).
>>>>>>
>>>>>> The migration draft proposes that clients use the same
>>>>>> nfs_client_id4 string for all of a server's IP addresses. Would a
>>>>>> server then be obliged to return NFS4ERR_CLID_IN_USE if a client
>>>>>> attempts a SETCLIENTID with the same boot verifier and
>>>>>> nfs_client_id4 on more than one IP address for the same server?
>>>>>
>>>>> That's also not this case, sorry, this time with all the
>>>>> conditions:
>>>>>
>>>>> 	- if the nfs_client_id4 is the same, and
>>>>> 	- if the flavor is auth_sys, and
>>>>> 	- if the client IP address is different,
>>>>> 	- then return NFS4ERR_INUSE.
>>>>
>>>> This still breaks for multi-homed servers and UCS clients. The
>>>> client IP address can be different depending on what server IP
>>>> address the client is accessing, but all the other parameters are
>>>> the same.
>>>
>>> OK. So probably there's nothing we can do to help here.
>>>
>>> As a bandaid maybe a rate-limited log message ("clientid X now in
>>> use
>>> from IP Y") might help debug these things....
>>
>> Since you guys keep Cc'ing me, I'll chime in with a rather naive
>> suggestion: if all that's required is a unique id for every client,
>> why
>> not use the MAC of the first network interface, independent of it
>> being
>> used for communication with the server?
>>
> I think this works fairly well for "real hardware", but I'm not so sure
> about clients running in VMs. (I don't really know how the VMs assign
> MAC addresses to their fake net interfaces and what uniqueness guarantees
> those have. I remember the old freebie VMware client for Windows just
> had a config file that assigned the MAC. I bet half the installations
> on the planet had the same MAC as the default config file:-)

But as I understand, the clientid doesn't have to globally unique, just
unique for the given NFS server. I think if you have two virtual
machines with the same MAC connecting to the same NFS server, you have
different problems anyway.


> ps: Also, although it's not very relevant, getting the MAC address of
>     the first ethernet interface isn't easy in FreeBSD. I have no idea
>     if the same is true of Linux. (I'd also be worried that "first"
>     might not be fixed?)

It doesn't need to be the same interface all the time, I just meant the
first as in not a specific one.


Best,


   -Nikolaus

-- 
 »Time flies like an arrow, fruit flies like a Banana.«

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