Weird Linux - FreeBSD/ZFS NFSv4 interoperability problem

[David Brodbeck]

On Fri, Sep 3, 2010 at 4:41 PM, Rick Macklem <rmacklem at uoguelph.ca> wrote:
>> (Note: I originally posted this to freebsd-questions, and it was
>> suggested I take it here.)
>>
>> While doing some interoperability testing between Linux and FreeBSD, I
>> came up with this unusual issue. I could use some help figuring out
>> if this is a bug, and if so, where to file it. Here's the scenario:
>>
>> - FreeBSD 8.1-RELEASE server, sharing a ZFS filesystem via NFSv4.
>> - Linux client (I've tested with RHEL 5.4 and Debian Lenny) mounting
>> said filesystem with NFSv4.
>> - A user on the Linux client does a Subversion checkout onto the
>> mounted filesystem.
>>
>> At the end of the checkout, access to the filesystem hangs. nfsd on
>> the FreeBSD server and rpciod on the Linux client seem to be in a
>> tight loop, and there's lots of network traffic between them. I can
>> reproduce this every time.
>>
>> The problem does not occur if the backing filesystem is UFS instead of
>> ZFS, if NFSv3 is used instead of NFSv4, or if the client is FreeBSD
>> instead of Linux.
>>
> If you email me a packet capture (probably only need a few seconds
> when it is the tight loop), I can look at it in wireshark.
> Something like "tcpdump -s 0 -w xxx host <client>" run on the server
> should do it. Then email me "xxx" as an attachment.

Here's a capture for you.  This is a Linux client (192.168.30.30)
working against a FreeBSD 8.1-RELEASE server (192.168.30.102).  If you
need a capture using FreeBSD 9, that'll require some more setup on my
part and I won't be able to get to it until Monday.