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 07022ECAAD1 for ; Tue, 30 Aug 2022 18:32:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229647AbiH3Scv (ORCPT ); Tue, 30 Aug 2022 14:32:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229685AbiH3Scq (ORCPT ); Tue, 30 Aug 2022 14:32:46 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 331B46C768; Tue, 30 Aug 2022 11:32:45 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id 74CEF61B2; Tue, 30 Aug 2022 14:32:44 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 74CEF61B2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1661884364; bh=t6A49DAKcUjYnrJBqtDT4iG90zCiYbqrgUVgWSnHASc=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=Od1O16flgP0Xp/wDCethqQnKUDrZ/sWnO/vOOWYf37FPP5PkOCwcJa40y5RAbAirz JnR6g9bJ10IVnbL21iyJz9nAZIDFZp7aoMH6NlbE5+7FAF6klH1QMd19Cw6jU5N0il 1yC+/0/77oqMetI0uoA7CU1QDEGDRrplh24MXNb0= Date: Tue, 30 Aug 2022 14:32:44 -0400 To: Jeff Layton Cc: Trond Myklebust , "zohar@linux.ibm.com" , "djwong@kernel.org" , "xiubli@redhat.com" , "brauner@kernel.org" , "linux-xfs@vger.kernel.org" , "linux-api@vger.kernel.org" , "neilb@suse.de" , "david@fromorbit.com" , "linux-kernel@vger.kernel.org" , "chuck.lever@oracle.com" , "linux-ceph@vger.kernel.org" , "linux-nfs@vger.kernel.org" , "tytso@mit.edu" , "viro@zeniv.linux.org.uk" , "jack@suse.cz" , "linux-ext4@vger.kernel.org" , "linux-btrfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "lczerner@redhat.com" , "adilger.kernel@dilger.ca" , "walters@verbum.org" Subject: Re: [PATCH v3 1/7] iversion: update comments with info about atime updates Message-ID: <20220830183244.GG26330@fieldses.org> References: <549776abfaddcc936c6de7800b6d8249d97d9f28.camel@kernel.org> <166181389550.27490.8200873228292034867@noble.neil.brown.name> <20220830132443.GA26330@fieldses.org> <20220830144430.GD26330@fieldses.org> <20220830151715.GE26330@fieldses.org> <3e8c7af5d39870c5b0dc61736a79bd134be5a9b3.camel@hammerspace.com> <4adb2abd1890b147dbc61a06413f35d2f147c43a.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4adb2abd1890b147dbc61a06413f35d2f147c43a.camel@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 30, 2022 at 01:02:50PM -0400, Jeff Layton wrote: > The fact that NFS kept this more loosely-defined is what allowed us to > elide some of the i_version bumps and regain a fair bit of performance > for local filesystems [1]. If the change attribute had been more > strictly defined like you mention, then that particular optimization > would not have been possible. > > This sort of thing is why I'm a fan of not defining this any more > strictly than we require. Later on, maybe we'll come up with a way for > filesystems to advertise that they can offer stronger guarantees. Yeah, the afs change-attribute-as-counter thing seems ambitious--I wouldn't even know how to define what exactly you're counting. My one question is whether it'd be worth just defining the thing as *increasing*. That's a lower bar. (Though admittedly we don't quite manage it now--see again 1631087ba872 "Revert "nfsd4: support change_attr_type attribute"".) --b.