From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [pnfs] [PATCH 0/2] fix nfsd stateid encoding Date: Mon, 11 Aug 2008 12:28:30 -0400 Message-ID: <20080811162830.GB772@fieldses.org> References: <48A04820.5000409@panasas.com> <20080811155842.GC32193@fieldses.org> <48A064BC.1050302@panasas.com> <76bd70e30808110917y5a9a1950l1d905f081bd7a819@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Benny Halevy , NFS list , pNFS Mailing List To: Chuck Lever Return-path: Received: from mail.fieldses.org ([66.93.2.214]:40081 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbYHKQ2e (ORCPT ); Mon, 11 Aug 2008 12:28:34 -0400 In-Reply-To: <76bd70e30808110917y5a9a1950l1d905f081bd7a819-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. --b. > Certainly there are already > missed opportunities for sharing XDR encoding and decoding between > callback and the forward channel.