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 778DDC77B7C for ; Fri, 5 May 2023 22:05:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232088AbjEEWFx (ORCPT ); Fri, 5 May 2023 18:05:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229719AbjEEWFt (ORCPT ); Fri, 5 May 2023 18:05:49 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E026A618C; Fri, 5 May 2023 15:05:21 -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 E429D6410B; Fri, 5 May 2023 22:04:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A297C433D2; Fri, 5 May 2023 22:04:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683324280; bh=f1jvZDrF9Qn33CLcZ4WNk/v3Df+AvMJXxv7DwWGW0QQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OkpKowf89TZVFXs+kZPV9yhxvlS1WPcn+RJAUjhk+F+NdGsM3DowjGujTCVspntEk cjONoTzL+Mbd5t+9AKB6wfFG/v2mMcL4zUbTCd68MALmZ0bvdAsdyqB1NiUPsHURQx Pb+EiF47Gw2FrzOLU0+uch5xJIwNkrwQ88DqtgRjz2heN6tSAyMM3taWJ6o/co195G InfdsysxEKZtg6MGDEsuLv05bAtcsJBM0d3KZPxDWL0S6H+Cc+wgMhp3zHymC2qu4N b7tWMZGshPp0ERKEWKp+Mkk6aHJZ+zyeGly/ASTr+Ej/LlVg2ok1XVQwXyBr+Dr0m5 X42vWMe7zA2bg== Date: Fri, 5 May 2023 15:04:39 -0700 From: "Darrick J. Wong" To: John Garry Cc: Dave Chinner , axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, martin.petersen@oracle.com, viro@zeniv.linux.org.uk, brauner@kernel.org, dchinner@redhat.com, jejb@linux.ibm.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, Prasad Singamsetty Subject: Re: [PATCH RFC 02/16] fs/bdev: Add atomic write support info to statx Message-ID: <20230505220439.GK15394@frogsfrogsfrogs> References: <20230503183821.1473305-1-john.g.garry@oracle.com> <20230503183821.1473305-3-john.g.garry@oracle.com> <20230503215846.GE3223426@dread.disaster.area> <96a2f875-7f99-cd36-e9c3-abbadeb9833b@oracle.com> <20230504224033.GJ3223426@dread.disaster.area> <644fe4aa-cb89-0c14-4c90-cc93bcc6bbc2@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <644fe4aa-cb89-0c14-4c90-cc93bcc6bbc2@oracle.com> Precedence: bulk List-ID: On Fri, May 05, 2023 at 09:01:58AM +0100, John Garry wrote: > On 04/05/2023 23:40, Dave Chinner wrote: > > Hi Dave, > > > > No, not yet. Is it normally expected to provide a proposed man page update > > > in parallel? Or somewhat later, when the kernel API change has some > > > appreciable level of agreement? > > Normally we ask for man page updates to be presented at the same > > time, as the man page defines the user interface that is being > > implemented. In this case, we need updates for the pwritev2() man > > page to document RWF_ATOMIC semantics, and the statx() man page to > > document what the variables being exposed mean w.r.t. RWF_ATOMIC. > > > > The pwritev2() man page is probably the most important one right now > > - it needs to explain the guarantees that RWF_ATOMIC is supposed to > > provide w.r.t. data integrity, IO ordering, persistence, etc. > > Indeed, it will need to explain exactly how this "multi-atomic-unit > > mulit-bio non-atomic RWF_ATOMIC" IO thing can be used safely and > > reliably, especially w.r.t. IO ordering and persistence guarantees > > in the face of crashes and power failures. Not to mention > > documenting error conditions specific to RWF_ATOMIC... > > > > It's all well and good to have some implementation, but without > > actually defining and documenting the*guarantees* that RWF_ATOMIC > > provides userspace it is completely useless for application > > developers. And from the perspective of a reviewer, without the > > documentation stating what the infrastructure actually guarantees > > applications, we can't determine if the implementation being > > presented is fit for purpose.... > > ok, understood. Obviously from any discussion so far there are many details > which the user needs to know about how to use this interface and what to > expect. > > We'll look to start working on those man page details now. Agreed. The manpage contents are what needs to get worked on at LSFMM where you'll have various block/fs/storage device people in the same room with which to discuss various issues and try to smooth out the misundertandings. (Also: I've decided to cancel my in-person attendance due to a sudden health issue. I'll still be in the room, just virtually now. :() --D > Thanks, > John