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=-2.3 required=3.0 tests=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 25B0EC1975A for ; Tue, 17 Mar 2020 22:55:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F348F20738 for ; Tue, 17 Mar 2020 22:55:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726721AbgCQWzK (ORCPT ); Tue, 17 Mar 2020 18:55:10 -0400 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:40709 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726476AbgCQWzK (ORCPT ); Tue, 17 Mar 2020 18:55:10 -0400 Received: from dread.disaster.area (pa49-195-202-68.pa.nsw.optusnet.com.au [49.195.202.68]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 8C05E3A2EC1; Wed, 18 Mar 2020 09:55:06 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1jEL73-0004ut-J1; Wed, 18 Mar 2020 09:55:05 +1100 Date: Wed, 18 Mar 2020 09:55:05 +1100 From: Dave Chinner To: Christoph Hellwig Cc: "Ober, Frank" , "linux-xfs@vger.kernel.org" Subject: Re: write atomicity with xfs ... current status? Message-ID: <20200317225505.GU10776@dread.disaster.area> References: <20200317191954.GA29982@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200317191954.GA29982@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=mqTaRPt+QsUAtUurwE173Q==:117 a=mqTaRPt+QsUAtUurwE173Q==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=SS2py6AdgQ4A:10 a=7-415B0cAAAA:8 a=bYIajXiraDDfxSwi2rkA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Mar 17, 2020 at 12:19:54PM -0700, Christoph Hellwig wrote: > Atomic writs are still waiting for more time to finish things off. > > That being said while I had a prototype to use the NVMe atomic write > size I will never submit that to mainline in that paticular form. > > NVMe does not have any flag to force atomic writes, thus a too large > or misaligned write will be executed by the device withour errors. > That kind of interface is way too fragile to be used in production. I didn't realise that the NVMe standard had such a glaring flaw. That basically makes atomic writes useless for anything that actually requires atomicity. Has the standard been fixed yet? And does this means that hardware with usable atomic writes is still years away? /me is left to wonder how the NVMe standards process screwed this up so badly.... Cheers, Dave. -- Dave Chinner david@fromorbit.com