Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751610AbdILQ74 (ORCPT ); Tue, 12 Sep 2017 12:59:56 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48800 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752468AbdILQ67 (ORCPT ); Tue, 12 Sep 2017 12:58:59 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jeff Mahoney , Aleksa Sarai , Nikolay Borisov , David Sterba Subject: [PATCH 4.9 05/14] btrfs: resume qgroup rescan on rw remount Date: Tue, 12 Sep 2017 09:58:19 -0700 Message-Id: <20170912165254.002939527@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170912165253.709627159@linuxfoundation.org> References: <20170912165253.709627159@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1541 Lines: 43 4.9-stable 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 Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/super.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1834,6 +1834,8 @@ 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);