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 E2EE4C54EE9 for ; Thu, 8 Sep 2022 19:08:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231394AbiIHTIE (ORCPT ); Thu, 8 Sep 2022 15:08:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229610AbiIHTIE (ORCPT ); Thu, 8 Sep 2022 15:08:04 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42085C0BD8; Thu, 8 Sep 2022 12:08:03 -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 dfw.source.kernel.org (Postfix) with ESMTPS id CF8AE61DF3; Thu, 8 Sep 2022 19:08:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1EDEC433D6; Thu, 8 Sep 2022 19:07:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662664082; bh=21IEzqn0tspcrehkVG8v49sph6nh4+Q9lVwsF/n31JI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=W44j+0rNX9Wr4l5p+JvMqUR/9vLJfFf1gWDVodt/LgY4a9cyx4OnEXO1P7z7GiVeY 4oJMzDqeoxUnTAUgQWXa5LZ06iJnpwnGGU3Ml6nj579m5Y0sxA0L7baIzvltKEau4n 3jXg8seWlg8JT7wmJYIbaZfgfNzVncTbiX9cRtN/AlgMQ4uJgTrshTm3F+INgI5YbK wySi0oviWAKyzjUJyus5X4ohmQvX2C6/f5rB6cxjNxAP3mwAOJ2cTpOqH4ieVqtqjD FANAIYQ3EaJlPOzzmNgamBhMOtcEj0sfDwP2OQo/Si+5JugYc+G5vfO/BI+Rc8gD2A 1hs0/Kv+aZ1hQ== Message-ID: <44efe219dbf511492b21a653905448d43d0f3363.camel@kernel.org> Subject: Re: [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field From: Jeff Layton To: "J. Bruce Fields" Cc: Theodore Ts'o , Jan Kara , NeilBrown , adilger.kernel@dilger.ca, djwong@kernel.org, david@fromorbit.com, trondmy@hammerspace.com, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, brauner@kernel.org, fweimer@redhat.com, linux-man@vger.kernel.org, linux-api@vger.kernel.org, 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 Date: Thu, 08 Sep 2022 15:07:58 -0400 In-Reply-To: <20220908182252.GA18939@fieldses.org> References: <79aaf122743a295ddab9525d9847ac767a3942aa.camel@kernel.org> <20220907125211.GB17729@fieldses.org> <771650a814ab1ff4dc5473d679936b747d9b6cf5.camel@kernel.org> <20220907135153.qvgibskeuz427abw@quack3> <166259786233.30452.5417306132987966849@noble.neil.brown.name> <20220908083326.3xsanzk7hy3ff4qs@quack3> <02928a8c5718590bea5739b13d6b6ebe66cac577.camel@kernel.org> <20220908155605.GD8951@fieldses.org> <9e06c506fd6b3e3118da0ec24276e85ea3ee45a1.camel@kernel.org> <20220908182252.GA18939@fieldses.org> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4 (3.44.4-1.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, 2022-09-08 at 14:22 -0400, J. Bruce Fields wrote: > On Thu, Sep 08, 2022 at 01:40:11PM -0400, Jeff Layton wrote: > > Yeah, ok. That does make some sense. So we would mix this into the > > i_version instead of the ctime when it was available. Preferably, we'd > > mix that in when we store the i_version rather than adding it afterward= . > >=20 > > Ted, how would we access this? Maybe we could just add a new (generic) > > super_block field for this that ext4 (and other filesystems) could > > populate at mount time? >=20 > Couldn't the filesystem just return an ino_version that already includes > it? >=20 Yes. That's simple if we want to just fold it in during getattr. If we want to fold that into the values stored on disk, then I'm a little less clear on how that will work. Maybe I need a concrete example of how that will work: Suppose we have an i_version value X with the previous crash counter already factored in that makes it to disk. We hand out a newer version X+1 to a client, but that value never makes it to disk. The machine crashes and comes back up, and we get a query for i_version and it comes back as X. Fine, it's an old version. Now there is a write. What do we do to ensure that the new value doesn't collide with X+1?=20 --=20 Jeff Layton