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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 235A6C4332F for ; Thu, 20 Oct 2022 06:59:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229880AbiJTG64 (ORCPT ); Thu, 20 Oct 2022 02:58:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229923AbiJTG63 (ORCPT ); Thu, 20 Oct 2022 02:58:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D43C51213F8; Wed, 19 Oct 2022 23:58:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6C48DB8269E; Thu, 20 Oct 2022 06:58:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0324FC433D6; Thu, 20 Oct 2022 06:58:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666249101; bh=gNWZd5H40IPgVGZtl+34qVIwNzNQ+boUybOYzZCAgH4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ilVIxiQjJQomaVAaYb2QTy49mE/zcyOh4m9FDwj28sXrvFedTs9NPcRvXaDnBJ4GI Cxiq4jfsTaOztspnUUhrsob2ezKk2aFEvWRHyIbwWELRzQNDdNehXcSHglRFoSSvoA QWaukBX4ZTDqDQYxWT0lu5W5gQcaWpS1mdZkTP5XxKuhrWGLgsFM3a9FxoOs1wKHRb Ngxs0n8pnaFx960AnjSxzERziXAxNZ2dbbuWsetzbTbrTw5Lx9YGXaBkUwE3xCqkNz S48IGWFFRptH4hn4lDmITsVuYGdPWvaofNFG49lm0nORJW+RMbde8MAqIjySLo392Q M1/RaSEr5AmLg== Date: Thu, 20 Oct 2022 08:58:13 +0200 From: Christian Brauner To: Jeff Layton Cc: "Darrick J. Wong" , tytso@mit.edu, adilger.kernel@dilger.ca, david@fromorbit.com, trondmy@hammerspace.com, neilb@suse.de, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, jack@suse.cz, bfields@fieldses.org, fweimer@redhat.com, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v7 0/9] fs: clean up handling of i_version counter Message-ID: <20221020065813.sdnrerbrvi75xlkp@wittgenstein> References: <20221017105709.10830-1-jlayton@kernel.org> <20221019111315.hpilifogyvf3bixh@wittgenstein> <2b167dd9bda17f1324e9c526d868cc0d995dc660.camel@kernel.org> <3fa8e13be8d75e694e8360a8e9552a92a4c14803.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3fa8e13be8d75e694e8360a8e9552a92a4c14803.camel@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Oct 19, 2022 at 04:36:47PM -0400, Jeff Layton wrote: > On Wed, 2022-10-19 at 08:45 -0700, Darrick J. Wong wrote: > > On Wed, Oct 19, 2022 at 08:18:15AM -0400, Jeff Layton wrote: > > > On Wed, 2022-10-19 at 13:13 +0200, Christian Brauner wrote: > > > > On Mon, Oct 17, 2022 at 06:57:00AM -0400, Jeff Layton wrote: > > > > > This patchset is intended to clean up the handling of the i_version > > > > > counter by nfsd. Most of the changes are to internal interfaces. > > > > > > > > > > This set is not intended to address crash resilience, or the fact that > > > > > the counter is bumped before a change and not after. I intend to tackle > > > > > those in follow-on patchsets. > > > > > > > > > > My intention is to get this series included into linux-next soon, with > > > > > an eye toward merging most of it during the v6.2 merge window. The last > > > > > patch in the series is probably not suitable for merge as-is, at least > > > > > until we sort out the semantics we want to present to userland for it. > > > > > > > > Over the course of the series I struggled a bit - and sorry for losing > > > > focus - with what i_version is supposed to represent for userspace. So I > > > > would support not exposing it to userspace before that. But that > > > > shouldn't affect your other changes iiuc. > > > > > > Thanks Christian, > > > > > > It has been a real struggle to nail this down, and yeah I too am not > > > planning to expose this to userland until we have this much better > > > defined. Patch #9 is just to give you an idea of what this would > > > ultimately look like. I intend to re-post the first 8 patches with an > > > eye toward merge in v6.2, once we've settled on the naming. On that > > > note... > > > > > > I believe you had mentioned that you didn't like STATX_CHANGE_ATTR for > > > the name, and suggested STATX_I_VERSION (or something similar), which I > > > later shortened to STATX_VERSION. > > > > > > Dave C. objected to STATX_VERSION, as "version" fields in a struct > > > usually refer to the version of the struct itself rather than the > > > version of the thing it describes. It also sort of implies a monotonic > > > counter, and I'm not ready to require that just yet. > > > > > > What about STATX_CHANGE for the name (with corresponding names for the > > > field and other flags)? That drops the redundant "_ATTR" postfix, while > > > being sufficiently vague to allow for alternative implementations in the > > > future. > > > > > > Do you (or anyone else) have other suggestions for a name? > > > > Welllll it's really a u32 whose value doesn't have any intrinsic meaning > > other than "if (value_now != value_before) flush_cache();" right? > > I think it really only tracks changes to file data, right? > > > > It's a u64, but yeah, you're not supposed to assign any intrinsic > meaning to the value itself. > > > STATX_CHANGE_COOKIE (wait, does this cookie augment i_ctime?) > > > > STATX_MOD_COOKIE (...or just file modifications/i_mtime?) > > > > STATX_MONITOR_COOKIE (...what are we monitoring??) > > > > STATX_MON_COOKIE > > > > STATX_COOKIE_MON > > > > STATX_COOKIE_MONSTER > > > > There we go. ;) > > > > In seriousness, I'd probably go with one of the first two. I wouldn't > > be opposed to the last one, either, but others may disagree. ;) > > > > --D > > > > > > STATX_CHANGE_COOKIE is probably the best one. I'll plan to go with that > unless someone has a better idea. Thanks for the suggestions! Sounds fine to me.