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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY autolearn=ham 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 B11FAC433E2 for ; Fri, 11 Sep 2020 16:03:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73FB221D6C for ; Fri, 11 Sep 2020 16:03:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="w/3+NHzi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726530AbgIKQDi (ORCPT ); Fri, 11 Sep 2020 12:03:38 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:55996 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726406AbgIKQCg (ORCPT ); Fri, 11 Sep 2020 12:02:36 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08BG07kn107571; Fri, 11 Sep 2020 16:02:25 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=V6ke8Cq1n6wcFqEzpKijYDVb/Pqi0IR4aKLJYOVKwRY=; b=w/3+NHzin16yboHBWp0W5dFWZDaCVi24cKJ9vyoyct3kdhFqJ0oY4U7P1TdcAzwGYCUB ErFGGGs8HZ7Vyi/XgD8Fto1fXgSSj6jyOUMh4C2PvJU54sXGBMq0DC6DQcCKVASEOAI0 PbVokvlwwlf0OV0x+Ah9uEQfwLzCv5W3hVsjGdjcR0kc/VtETBFXjZKIXdrZBFktD5OT T36Hfk7c6c2c686Px6lGOvEg7eJaH3sVFs9yecRZvhR5iTMGNrQEes83S6KsZrVQCC8P NfQC/Ux0ANrdVbRz0i7+a0o1CAKQh8nTQ0NQYGuWrJrHwotZrjPOgbI8FPa4i9PlSCAb Mw== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 33c3aneyv9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 11 Sep 2020 16:02:24 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08BFxjC0010371; Fri, 11 Sep 2020 16:02:24 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 33dacq5wgj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 11 Sep 2020 16:02:24 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 08BG2Nh8024822; Fri, 11 Sep 2020 16:02:23 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 11 Sep 2020 09:02:23 -0700 Date: Fri, 11 Sep 2020 09:02:22 -0700 From: "Darrick J. Wong" To: Brian Foster Cc: xfs , Dave Chinner , Eric Sandeen Subject: Re: [PATCH v2] xfs: deprecate the V4 format Message-ID: <20200911160222.GF7964@magnolia> References: <20200910224842.GR7955@magnolia> <20200911113158.GA1194939@bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200911113158.GA1194939@bfoster> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9741 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 bulkscore=0 phishscore=0 adultscore=0 suspectscore=1 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009110130 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9741 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 priorityscore=1501 clxscore=1015 bulkscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 suspectscore=1 adultscore=0 mlxscore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009110130 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Fri, Sep 11, 2020 at 07:31:58AM -0400, Brian Foster wrote: > On Thu, Sep 10, 2020 at 03:48:42PM -0700, Darrick J. Wong wrote: > > From: Darrick J. Wong > > > > The V4 filesystem format contains known weaknesses in the on-disk format > > that make metadata verification diffiult. In addition, the format will > > does not support dates past 2038 and will not be upgraded to do so. > > Therefore, we should start the process of retiring the old format to > > close off attack surfaces and to encourage users to migrate onto V5. > > > > Therefore, make XFS V4 support a configurable option. For the first > > period it will be default Y in case some distributors want to withdraw > > support early; for the second period it will be default N so that anyone > > who wishes to continue support can do so; and after that, support will > > be removed from the kernel. > > > > Signed-off-by: Darrick J. Wong > > --- > > v2: define what is a V4 filesystem, update the administrator guide > > --- > > Seems reasonable to me... > > > Documentation/admin-guide/xfs.rst | 20 ++++++++++++++++++++ > > fs/xfs/Kconfig | 23 +++++++++++++++++++++++ > > fs/xfs/xfs_mount.c | 11 +++++++++++ > > 3 files changed, 54 insertions(+) > > > > diff --git a/Documentation/admin-guide/xfs.rst b/Documentation/admin-guide/xfs.rst > > index f461d6c33534..68d69733a1df 100644 > > --- a/Documentation/admin-guide/xfs.rst > > +++ b/Documentation/admin-guide/xfs.rst > > @@ -210,6 +210,25 @@ When mounting an XFS filesystem, the following options are accepted. > > inconsistent namespace presentation during or after a > > failover event. > > > > +Deprecation of V4 Format > > +======================== > > + > > +The V4 filesystem format lacks certain features that are supported by > > +the V5 format, such as metadata checksumming, strengthened metadata > > +verification, and the ability to store timestamps past the year 2038. > > +Because of this, the V4 format is deprecated. All users should upgrade > > +by backing up their files, reformatting, and restoring from the backup. > > + > > +Administrators and users can detect a V4 filesystem by running xfs_info > > +against a filesystem mountpoint and checking for a string beginning with > > +"crc=". If the string "crc=0" is found, or no "crc=" string is found, > > +the filesystem is a V4 filesystem. > > + > > +The deprecation will take place in two parts. Support for mounting V4 > > +filesystems can now be disabled at kernel build time via Kconfig option. > > +The option will default to yes until September 2025, at which time it > > +will be changed to default to no. In September 2030, support will be > > +removed from the codebase entirely. > > > > Deprecated Mount Options > > ======================== > > @@ -217,6 +236,7 @@ Deprecated Mount Options > > =========================== ================ > > Name Removal Schedule > > =========================== ================ > > +Mounting with V4 filesystem September 2030 > > =========================== ================ > > > > > > diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig > > index e685299eb3d2..5970d0f77db9 100644 > > --- a/fs/xfs/Kconfig > > +++ b/fs/xfs/Kconfig > > @@ -22,6 +22,29 @@ config XFS_FS > > system of your root partition is compiled as a module, you'll need > > to use an initial ramdisk (initrd) to boot. > > > > +config XFS_SUPPORT_V4 > > + bool "Support deprecated V4 (crc=0) format" > > + default y > > + help > > + The V4 filesystem format lacks certain features that are supported > > + by the V5 format, such as metadata checksumming, strengthened > > + metadata verification, and the ability to store timestamps past the > > + year 2038. Because of this, the V4 format is deprecated. All users > > + should upgrade by backing up their files, reformatting, and restoring > > + from the backup. > > + > > + Administrators and users can detect a V4 filesystem by running > > + xfs_info against a filesystem mountpoint and checking for a string > > + beginning with "crc=". If the string "crc=0" is found, or no "crc=" > > + string is found, the filesystem is a V4 filesystem. > > + > > + This option will become default N in September 2025. Support for the > > + V4 format will be removed entirely in September 2030. Distributors > > + can say N here to withdraw support earlier. > > + > > + To continue supporting the old V4 format (crc=0), say Y. > > + To close off an attack surface, say N. > > + > > config XFS_QUOTA > > bool "XFS Quota support" > > depends on XFS_FS > > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c > > index ed69c4bfda71..3678dfeecd64 100644 > > --- a/fs/xfs/xfs_mount.c > > +++ b/fs/xfs/xfs_mount.c > > @@ -315,6 +315,17 @@ xfs_readsb( > > goto release_buf; > > } > > > > +#ifndef CONFIG_XFS_SUPPORT_V4 > > + /* V4 support is undergoing deprecation. */ > > + if (!xfs_sb_version_hascrc(sbp)) { > > + if (loud) > > + xfs_warn(mp, > > + "Deprecated V4 format (crc=0) not supported by kernel."); > > + error = -EINVAL; > > + goto release_buf; > > + } > > +#endif > > + > > Should we not have a (oneshot?) warning for systems that choose to > continue to support and use v4 filesystems? ISTM that's the best way to > ensure there's feedback on this change earlier rather than later, or > otherwise encourage such users to reformat with v5 at the next available > opportunity... hm, yes. > BTW, any reason this is in xfs_readsb() vs. xfs_fc_fill_super() where we > have various other version/feature checks and warnings? no particular reason. i like the idea of moving this chunk over there. --d > Brian > > > /* > > * We must be able to do sector-sized and sector-aligned IO. > > */ > > >