From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38F17C2D0E4 for ; Fri, 20 Nov 2020 22:38:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BBAD22470 for ; Fri, 20 Nov 2020 22:38:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fieldses.org header.i=@fieldses.org header.b="i+lwT4z9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728719AbgKTWid (ORCPT ); Fri, 20 Nov 2020 17:38:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728707AbgKTWic (ORCPT ); Fri, 20 Nov 2020 17:38:32 -0500 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1E1CC0613CF for ; Fri, 20 Nov 2020 14:38:32 -0800 (PST) Received: by fieldses.org (Postfix, from userid 2815) id 2E8206E9D; Fri, 20 Nov 2020 17:38:31 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 2E8206E9D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1605911911; bh=5bVe9bi2/bQavzWQkIxUuzrWKCsg7lset2yREDevtqg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=i+lwT4z9rf216mxxqDbfHvXb+hrmQLEToGI3p97TE8kg8mvvRZObxYefmXA5eDLNv xFiZo7Tzvg+DqvX748JDit0F41tldexDosuxMXhWaNb3e0F4P3Zyj7FbSGyQlrboCK Lc2Vv+VRdYf8Px+rtxN1VfXPeaoO7e8A47uBAOn4= Date: Fri, 20 Nov 2020 17:38:31 -0500 From: "J. Bruce Fields" To: Jeff Layton Cc: "J. Bruce Fields" , Daire Byrne , Trond Myklebust , linux-cachefs , linux-nfs Subject: Re: [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute Message-ID: <20201120223831.GB7705@fieldses.org> References: <20201117031601.GB10526@fieldses.org> <1605583086-19869-1-git-send-email-bfields@redhat.com> <1605583086-19869-2-git-send-email-bfields@redhat.com> <20201117152636.GC4556@fieldses.org> <725499c144317aac1a03f0334a22005588dbdefc.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <725499c144317aac1a03f0334a22005588dbdefc.camel@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Tue, Nov 17, 2020 at 10:34:57AM -0500, Jeff Layton wrote: > On Tue, 2020-11-17 at 10:26 -0500, J. Bruce Fields wrote: > > On Tue, Nov 17, 2020 at 07:34:49AM -0500, Jeff Layton wrote: > > > I don't think I described what I was thinking well. Let me try again... > > > > > > There should be no need to change the code in iversion.h -- I think we > > > can do this in a way that's confined to just nfsd/export code. > > > > > > What I would suggest is to have nfsd4_change_attribute call the > > > fetch_iversion op if it exists, instead of checking IS_I_VERSION and > > > doing the stuff in that block. If fetch_iversion is NULL, then just use > > > the ctime. > > > > > > Then, you just need to make sure that the filesystems' export_ops have > > > an appropriate fetch_iversion vector. xfs, ext4 and btrfs can just call > > > inode_query_iversion, and NFS and Ceph can call inode_peek_iversion_raw. > > > The rest of the filesystems can leave fetch_iversion as NULL (since we > > > don't want to use it on them). > > > > Thanks for your patience, that makes sense, I'll try it. > > > > There is one gotcha in here though... ext4 needs to also handle the case > where SB_I_VERSION is not set. The simple fix might be to just have > different export ops for ext4 based on whether it was mounted with -o > iversion or not, but maybe there is some better way to do it? I was thinking ext4's export op could check for I_VERSION on its own and vary behavior based on that. I'll follow up with new patches in a moment. I think the first one's all that's needed to fix the problem Daire identified. I'm a little less sure of the rest. Lightly tested, just by running them through my usual regression tests (which don't re-export) and then running connectathon on a 4.2 re-export of a 4.2 mount. The latter triggered a crash preceded by a KASAN use-after free warning. Looks like it might be a problem with blocking lock notifications, probably not related to these patches. --b.