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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 CC1C8C433EA for ; Tue, 21 Jul 2020 16:06:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A14DA2073A for ; Tue, 21 Jul 2020 16:06:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="F3w1juxl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730175AbgGUQGB (ORCPT ); Tue, 21 Jul 2020 12:06:01 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:43422 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728219AbgGUQGA (ORCPT ); Tue, 21 Jul 2020 12:06:00 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06LG1UVD048595; Tue, 21 Jul 2020 16:05:47 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=LSsHWv/Ry310RdY8DfK9RbXStKhT7a/ijlTJRfNYKBw=; b=F3w1juxlH5QSmHd+imiuYdZGWjKHnzEv/NKoyKwhIc/s7GN+vHaAzidQDTB/DhjAEyeT d/Gx8vucWDL2jzjYsFydj9gp/ppR/d1HKXkpQ4M+nBfyMU/lBxulYLTGIP63iUbn+XMa 5AJJ7SdGe5ThlcDK+Ad12dSY6V2RP2uwwvf/W6jgJCOAzcaF6075T2S5EuIypvbdsOMZ 5GZy7LilCugLI4xLlHnpqSBJQc4HmAEDrO9FuVijPQrTmhxzqZDLoVgUPaZUuxoFXLdV 7XUINu6FhLHiAiQirWudIChRb2+CCLxB/+abECYiU5zPJXFWz1kdRwMYbxCbqSB925uM yw== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 32bs1me5ju-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 21 Jul 2020 16:05:47 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06LFi0cn060765; Tue, 21 Jul 2020 16:03:47 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 32e33ght6u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Jul 2020 16:03:47 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 06LG3i8F028849; Tue, 21 Jul 2020 16:03:45 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 21 Jul 2020 16:03:44 +0000 Date: Tue, 21 Jul 2020 09:03:42 -0700 From: "Darrick J. Wong" To: Matthew Wilcox Cc: Christoph Hellwig , Goldwyn Rodrigues , Dave Chinner , Damien Le Moal , Naohiro Aota , Johannes Thumshirn , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, cluster-devel@redhat.com, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, Michael Kerrisk , linux-man@vger.kernel.org Subject: Re: RFC: iomap write invalidation Message-ID: <20200721160342.GC3151642@magnolia> References: <20200713074633.875946-1-hch@lst.de> <20200720215125.bfz7geaftocy4r5l@fiona> <20200721145313.GA9217@lst.de> <20200721150432.GH15516@casper.infradead.org> <20200721150615.GA10330@lst.de> <20200721151437.GI15516@casper.infradead.org> <20200721151616.GA11074@lst.de> <20200721153136.GJ15516@casper.infradead.org> <20200721154240.GB11652@lst.de> <20200721155201.GL15516@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200721155201.GL15516@casper.infradead.org> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9689 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 suspectscore=1 malwarescore=0 mlxlogscore=999 spamscore=0 bulkscore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007210112 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9689 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 bulkscore=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 malwarescore=0 clxscore=1015 spamscore=0 mlxscore=0 impostorscore=0 phishscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007210113 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jul 21, 2020 at 04:52:01PM +0100, Matthew Wilcox wrote: > On Tue, Jul 21, 2020 at 05:42:40PM +0200, Christoph Hellwig wrote: > > On Tue, Jul 21, 2020 at 04:31:36PM +0100, Matthew Wilcox wrote: > > > > Umm, no. -ENOTBLK is internal - the file systems will retry using > > > > buffered I/O and the error shall never escape to userspace (or even the > > > > VFS for that matter). > > > > > > Ah, I made the mistake of believing the comments that I could see in > > > your patch instead of reading the code. > > > > > > Can I suggest deleting this comment: > > > > > > /* > > > * No fallback to buffered IO on errors for XFS, direct IO will either > > > * complete fully or fail. > > > */ > > > > > > and rewording this one: > > > > > > /* > > > * Allow a directio write to fall back to a buffered > > > * write *only* in the case that we're doing a reflink > > > * CoW. In all other directio scenarios we do not > > > * allow an operation to fall back to buffered mode. > > > */ > > > > > > as part of your revised patchset? > > > > That isn't actually true. In current mainline we only fallback on > > reflink RMW cases, but with this series we also fall back for > > invalidation failures. > > ... that's why I'm suggesting that you delete the first one and rewrite > the second one. Because they aren't true. /* * We allow only three outcomes of a directio: (1) it succeeds * completely; (2) it fails with a negative error code; or (3) it * returns -ENOTBLK to signal that we should fall back to buffered IO. * * The third scenario should only happen if iomap refuses to perform the * direct IO, or the direct write request requires CoW but is not aligned * to the filesystem block size. */ ? --D