Re: [pnfs] [PATCH 0/2] fix nfsd stateid encoding

Benny Halevy
2008-08-11T16:11:46Z

On Aug. 11, 2008, 18:58 +0300, "J. Bruce Fields" <bfields@fieldses.org> wrote:
> On Mon, Aug 11, 2008 at 05:09:36PM +0300, Benny Halevy wrote:
>> Bruce, in a couple locations the nfsd needs to encode the stateid.seqid
>> as a uint32_t rather than as opaque.
>
> Agreed, thanks.
>
> Though I have a hard time figuring out whether this has any impact in
> practice. Presumably the only change on the wire is that we'll get the
> endianness of the stateid4.seqid right? But that field is mostly opaque
> to the client anyway; 3530 says
>
> The server is required to increment the seqid field
> monotonically at each transition of the stateid. This is
> important since the client will inspect the seqid in OPEN
> stateids to determine the order of OPEN processing done by the
> server.
>
> but doesn't say why this is important. I'm sure this has been brought
> up on the ietf list before, but can't recall whether someone came up
> with a justification for the importance of this.
>
> Anyway, so I figure these should be queued up for the next (2.6.28)
> merge window. Thanks!

Actually, I think this breaks delegreturn.
Since we decode the stateid.si_generation correctly, it will get swabbed
in delegreturn on little-endian servers. This will cause
nfs4_preprocess_stateid_op/check_stateid_generation as called by
nfsd4_delegreturn to fail. And eventually, unhash_delegation
wouldn't be called.

Hence, I think these patches are appropriate for 2.6.27 and
even to older stable releases.

Benny

>
> --b.
>
>> Patch #1 fixes that for cb_recall.
>> Patch #2 fixes the deleg stateid returned by open.
>>
>> The patches should apply to linux-2.6/master
>> commit 796aadeb1b2db9b5d463946766c5bbfd7717158c
>>
>> Benny
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