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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 41A8EC433DF for ; Mon, 20 Jul 2020 03:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C7FE2250E for ; Mon, 20 Jul 2020 03:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726687AbgGTDVt (ORCPT ); Sun, 19 Jul 2020 23:21:49 -0400 Received: from mail106.syd.optusnet.com.au ([211.29.132.42]:41660 "EHLO mail106.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726499AbgGTDVt (ORCPT ); Sun, 19 Jul 2020 23:21:49 -0400 Received: from dread.disaster.area (pa49-180-53-24.pa.nsw.optusnet.com.au [49.180.53.24]) by mail106.syd.optusnet.com.au (Postfix) with ESMTPS id 314A55EC7FB; Mon, 20 Jul 2020 13:21:44 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1jxMN5-0002S0-Cx; Mon, 20 Jul 2020 13:21:43 +1000 Date: Mon, 20 Jul 2020 13:21:43 +1000 From: Dave Chinner To: Brian Foster Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH v2] repair: use fs rootino for dummy parent value instead of zero Message-ID: <20200720032143.GC2005@dread.disaster.area> References: <20200715140836.10197-4-bfoster@redhat.com> <20200717115920.59986-1-bfoster@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717115920.59986-1-bfoster@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=QKgWuTDL c=1 sm=1 tr=0 a=moVtWZxmCkf3aAMJKIb/8g==:117 a=moVtWZxmCkf3aAMJKIb/8g==:17 a=kj9zAlcOel0A:10 a=_RQrkK6FrEwA:10 a=20KFwNOVAAAA:8 a=7-415B0cAAAA:8 a=qP0JENCKDnoD14qI7MsA: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 Fri, Jul 17, 2020 at 07:59:20AM -0400, Brian Foster wrote: > If a directory inode has an invalid parent ino on disk, repair > replaces the invalid value with a dummy value of zero in the buffer > and NULLFSINO in the in-core parent tracking. The zero value serves > no functional purpose as it is still an invalid value and the parent > must be repaired by phase 6 based on the in-core state before the > buffer can be written out. A consequence of using an invalid dummy > value is that phase 6 requires custom verifier infrastructure to > detect the invalid parent inode and temporarily replace it while the > core fork verifier runs. If we use a valid inode number as a dummy > value earlier in repair, this workaround can be removed. > > An obvious choice for a valid dummy parent inode value is the > orphanage inode. However, the orphanage inode is not allocated until > much later in repair when the filesystem structure is established as > sound and placement of orphaned inodes is imminent. In this case, it > is too early to know for sure whether the associated inodes are > orphaned because a directory traversal later in repair can locate > references to the inode and repair the parent value based on the > structure of the directory tree. > > Given all of this, escalate the preexisting workaround from the > custom verifier in phase 6 and set the root inode value as a dummy > parent for shortform directories with an invalid on-disk parent. The > in-core parent is still tracked as NULLFSINO and so forces repair to > either update the parent or orphan the inode before repair > completes. > > Signed-off-by: Brian Foster > Reviewed-by: Christoph Hellwig > --- > > v2: > - Update patch subject and commit log. Looks good. Reviewed-by: Dave Chinner -- Dave Chinner david@fromorbit.com