From: Benny Halevy Subject: Re: [pnfs] [PATCH] nfsd: use nfs client rpc callback program Date: Thu, 25 Sep 2008 22:30:33 +0300 Message-ID: <48DBE6D9.3010603@panasas.com> References: <20080917231018.GA5723@fieldses.org> <48D193EE.2020805@panasas.com> <48D19C74.8000303@panasas.com> <48D2AAF7.6060808@panasas.com> <20080924163528.GB5772@fieldses.org> <1222275582.7390.8.camel@localhost> <20080924172134.GI5772@fieldses.org> <1222277168.7390.19.camel@localhost> <20080924174230.GJ5772@fieldses.org> <1222281745.7390.34.camel@localhost> <20080924184934.GK5772@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Trond Myklebust , Olga Kornievskaia , linux-nfs@vger.kernel.org, pnfs mailing list , Trond Myklebust To: "J. Bruce Fields" Return-path: Received: from gw-ca.panasas.com ([66.104.249.162]:15030 "EHLO laguna.int.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753339AbYIYTas (ORCPT ); Thu, 25 Sep 2008 15:30:48 -0400 In-Reply-To: <20080924184934.GK5772@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On 09/24/2008 9:49:34 pm +0300, "J. Bruce Fields" wrote: > On Wed, Sep 24, 2008 at 02:42:25PM -0400, Trond Myklebust wrote: >> On Wed, 2008-09-24 at 13:42 -0400, J. Bruce Fields wrote: >> >>> If by "broken" you mean, "introduces a new kernel bug", I don't see it. >> I mean it introduces utterly unnecessary complications that may return >> to bite us in the arse at a future time. > > OK, that's the answer I was looking for, thanks. > >> Remember how we once said that it would never make sense for child >> clones to call the portmapper, and so we added the BUG_ON() in >> rpcb_getport_async; well guess what, we currently have a bug to fix... > > No, I don't remember that. But yes, I can see how in general this sort > of thing could make the code harder to maintain. > >> One pretty obvious fix is to simply move the release method so that it >> doesn't occur when you release a child. The disadvantage is that a child >> may then not change its program to one that requires a release method >> (do we need that?). > > I doubt we need that, but... > >> Another fix would be to add a refcount to the rpc_program structure... > > ... a refcount seems more straightforward. Benny, what do you think? I agree. I'll send a patch hopefully tomorrow. Would you like that combined with the one I sent or as a separate one? (I'm inclined towards the latter). One more thing that seems to need fixing is rpc_bind_new_program which now uses the passed-in program->cl_stats but doesn't point to the passed-in program, but rather it only extracts its name, number, and stats. Since program->stats may possibly go away with the program in the refcounted world I think we should get a reference on the program here too. That observed, it may also be a good idea to get rid of clnt->cl_stats altogether and use clnt->program->stats instead to prevent any discrepancy. Benny > > --b.