From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benny Halevy Subject: Re: [pnfs] [PATCH 0/2] fix nfsd stateid encoding Date: Mon, 11 Aug 2008 20:39:59 +0300 Message-ID: <48A0796F.20402@panasas.com> References: <48A04820.5000409@panasas.com> <20080811155842.GC32193@fieldses.org> <48A064BC.1050302@panasas.com> <76bd70e30808110917y5a9a1950l1d905f081bd7a819@mail.gmail.com> <20080811162830.GB772@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Chuck Lever , NFS list , pNFS Mailing List To: "J. Bruce Fields" Return-path: Received: from gw-colo-pa.panasas.com ([66.238.117.130]:22318 "EHLO natasha.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751458AbYHKRk1 (ORCPT ); Mon, 11 Aug 2008 13:40:27 -0400 In-Reply-To: <20080811162830.GB772@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Aug. 11, 2008, 19:28 +0300, "J. Bruce Fields" wrote: > On Mon, Aug 11, 2008 at 12:17:35PM -0400, Chuck Lever wrote: >> Hi Benny- >> >> On Mon, Aug 11, 2008 at 12:11 PM, Benny Halevy wrote: >>> On Aug. 11, 2008, 18:58 +0300, "J. Bruce Fields" 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. >> Sounds plausible, good catch. Yet another reason we should have an >> easy-to-access delegation counter metric on both the client and >> server. >> >> I wonder, since you found three separate places where this is needed: >> should you construct a helper function? > > A stateid encoder/decoder? Sure, that could be a good idea. Cool. Would you like me to rework the patches I've already sent or send a patch adding the helpers on top of them? Benny > > --b. > >> Certainly there are already >> missed opportunities for sharing XDR encoding and decoding between >> callback and the forward channel.