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 03462C43334 for ; Wed, 20 Jul 2022 16:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233188AbiGTQqG (ORCPT ); Wed, 20 Jul 2022 12:46:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233067AbiGTQqF (ORCPT ); Wed, 20 Jul 2022 12:46:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A28343E79; Wed, 20 Jul 2022 09:46:05 -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 A9BD361DB5; Wed, 20 Jul 2022 16:46:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7303AC3411E; Wed, 20 Jul 2022 16:46:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1658335564; bh=bO/72wAs9HIZh7WXwkr34dOo62ZEdL5rFbqhoO2fP7c=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=uOnLo8FXZZtBjV8LmyAn8IA7rXsobB34IdKFGAni47kX2wGF7tdkC8gsushaGGBuK 2sSJlHoxQQjKB3SrnoaOnRCVMmXSXxktu8FIhrh1Aj+OnZBg9D4M2QN7nTvWfQ/ikZ xhX4Lvpek5FGEkFIhbLTcwTN3+jP8MU3tNh7GUbRb3UeXfB5vSwC2SE7uzvTQjTFUO 2L0Z2TEwRY2u6cObazkl9/JGUDd0YIDK/J8OFF+4qj3lk9PDEGSNDCm+vcvkOitBYW lshGAoI+lCizz0KLw7++Kk0o72pauors5p8ShtXERAmtDiDBeLsF3tLnnEFTqbWmIX nSKW5zvyXnHQA== Message-ID: Subject: Re: should we make "-o iversion" the default on ext4 ? From: Jeff Layton To: Benjamin Coddington Cc: Lukas Czerner , tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-fsdevel Date: Wed, 20 Jul 2022 12:46:01 -0400 In-Reply-To: <7F6417C7-1261-4C98-96B1-CB15744C04C1@redhat.com> References: <69ac1d3ef0f63b309204a570ef4922d2684ed7f9.camel@kernel.org> <20220720141546.46l2d7bxwukjhtl7@fedora> <7F6417C7-1261-4C98-96B1-CB15744C04C1@redhat.com> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.3 (3.44.3-1.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, 2022-07-20 at 12:29 -0400, Benjamin Coddington wrote: > On 20 Jul 2022, at 12:15, Jeff Layton wrote: >=20 > > On Wed, 2022-07-20 at 11:56 -0400, Benjamin Coddington wrote: > > > On 20 Jul 2022, at 10:38, Jeff Layton wrote: > > > > On Wed, 2022-07-20 at 16:15 +0200, Lukas Czerner wrote: > > > > >=20 > > > > > Is there a different way I am not seeing? > > > > >=20 > > > >=20 > > > > Right, implementing this is the difficult bit actually since this u= ses a > > > > MS_* flag.=A0If we do make this the default, we'd definitely want t= o > > > > continue allowing "-o noiversion" to disable it. > > > >=20 > > > > Could we just reverse the default in libmount? It might cause this = to > > > > suddenly be enabled in some deployments, but in most cases, people > > > > wouldn't even notice and they could still specify -o noiversion to = turn > > > > it off. > > > >=20 > > > > Another idea would be to introduce new mount options for this, but > > > > that's kind of nasty from a UI standpoint. > > >=20 > > > Is it safe to set SB_I_VERSION at export time? If so, export_operati= ons > > > could grow an ->enable_iversion(). > > >=20 > >=20 > > That sounds like it might be problematic. > >=20 > > Consider the case where a NFSv4 client has cached file data and the > > change attribute for the file. Server then reboots, but before the > > export happens a local user makes a change to the file and it doesn't > > update the i_version. >=20 > Nfsd currently uses both ctime and i_version if its available, I'd expect > that eliminates this case. >=20 Good point, that probably would. Still, I'd rather we just enable this wholesale if we can get away with it. There's still some interest in exposing i_version to userland via statx or the like, so I'd rather not assume that only nfsd will care about it. --=20 Jeff Layton