From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752720AbdKVCp6 (ORCPT ); Tue, 21 Nov 2017 21:45:58 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:57468 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412AbdKVCk4 (ORCPT ); Tue, 21 Nov 2017 21:40:56 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David Sterba" , "Nikolay Borisov" , "Jeff Mahoney" , "Aleksa Sarai" Date: Wed, 22 Nov 2017 01:58:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 034/133] btrfs: resume qgroup rescan on rw remount In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.51-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Aleksa Sarai commit 6c6b5a39c4bf3dbd8cf629c9f5450e983c19dbb9 upstream. Several distributions mount the "proper root" as ro during initrd and then remount it as rw before pivot_root(2). Thus, if a rescan had been aborted by a previous shutdown, the rescan would never be resumed. This issue would manifest itself as several btrfs ioctl(2)s causing the entire machine to hang when btrfs_qgroup_wait_for_completion was hit (due to the fs_info->qgroup_rescan_running flag being set but the rescan itself not being resumed). Notably, Docker's btrfs storage driver makes regular use of BTRFS_QUOTA_CTL_DISABLE and BTRFS_IOC_QUOTA_RESCAN_WAIT (causing this problem to be manifested on boot for some machines). Cc: Jeff Mahoney Fixes: b382a324b60f ("Btrfs: fix qgroup rescan resume on mount") Signed-off-by: Aleksa Sarai Reviewed-by: Nikolay Borisov Tested-by: Nikolay Borisov Signed-off-by: David Sterba [bwh: Backported to 3.16: add #include "qgroup.h"] Signed-off-by: Ben Hutchings --- --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -59,6 +59,7 @@ #include "free-space-cache.h" #include "backref.h" #include "tests/btrfs-tests.h" +#include "qgroup.h" #define CREATE_TRACE_POINTS #include @@ -1495,6 +1496,8 @@ static int btrfs_remount(struct super_bl goto restore; } + btrfs_qgroup_rescan_resume(fs_info); + if (!fs_info->uuid_root) { btrfs_info(fs_info, "creating UUID tree"); ret = btrfs_create_uuid_tree(fs_info);