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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3AC49C10DCE for ; Wed, 18 Mar 2020 07:54:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CEB32076F for ; Wed, 18 Mar 2020 07:54:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="O4AC9Wyx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726933AbgCRHyZ (ORCPT ); Wed, 18 Mar 2020 03:54:25 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36188 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbgCRHyZ (ORCPT ); Wed, 18 Mar 2020 03:54:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HouNVHvMelsMPW3Va1xvwZaP0gHrLhJSoexQ7+ZDTeE=; b=O4AC9WyxivztuP4hUfHLpatOIy xL+taQmGEu6c5Y9xJiq9fom9iPhRbrB/ol+/PfnMxtztbVrYl9BEQHmEDtTLyNKh97zmw5ftejReF VCUw90PNRLSONCYkd/FYkPP/AkpBJMB5oMPlxVOTASC2pgQU5mKI5IOAHpULImkcn8T425K/c5hFa 8FC4k7MYEVs2ow7aE6U756rwL2YqvBrhReQgVgFsxHAj6/SEHtCGKSRyi9YTkEBNDZ7yicDmihkO2 mDbooMUCJ8xgf9BDkb/BX1wKDJOkAKplTjfNrC4axDHb63iBzm1ju3W7wTvKBhiz2LTTIuPdTIutR 7LzTuMtQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jETWy-0000wG-7h; Wed, 18 Mar 2020 07:54:24 +0000 Date: Wed, 18 Mar 2020 00:54:24 -0700 From: Christoph Hellwig To: Dave Chinner Cc: Christoph Hellwig , "Ober, Frank" , "linux-xfs@vger.kernel.org" Subject: Re: write atomicity with xfs ... current status? Message-ID: <20200318075424.GA24276@infradead.org> References: <20200317191954.GA29982@infradead.org> <20200317225505.GU10776@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200317225505.GU10776@dread.disaster.area> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Mar 18, 2020 at 09:55:05AM +1100, Dave Chinner wrote: > > 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? No. > And > does this means that hardware with usable atomic writes is still > years away? At least for the hardware I'm familiar with checking a flag and failing it if the conditions are not met might be a relatively simple firmware fix. It just needs a big enough customer to ask for, not just some Linux developers.