From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q7N559C6136057 for ; Thu, 23 Aug 2012 00:05:09 -0500 Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id 1LXWgCI33ExKhOUF for ; Wed, 22 Aug 2012 22:05:54 -0700 (PDT) Received: from disappointment ([192.168.1.1]) by dastard with esmtp (Exim 4.76) (envelope-from ) id 1T4Pbf-0003Jv-5q for xfs@oss.sgi.com; Thu, 23 Aug 2012 15:05:23 +1000 Received: from dave by disappointment with local (Exim 4.80) (envelope-from ) id 1T4Pbf-0003ii-3U for xfs@oss.sgi.com; Thu, 23 Aug 2012 15:05:23 +1000 From: Dave Chinner Subject: [PATCH 088/102] xfs: protect xfs_sync_worker with s_umount semaphore Date: Thu, 23 Aug 2012 15:02:46 +1000 Message-Id: <1345698180-13612-89-git-send-email-david@fromorbit.com> In-Reply-To: <1345698180-13612-1-git-send-email-david@fromorbit.com> References: <1345698180-13612-1-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com From: Ben Myers Upstream commit: 1307bbd2af67283131728637e9489002adb26f10 xfs_sync_worker checks the MS_ACTIVE flag in s_flags to avoid doing work during mount and unmount. This flag can be cleared by unmount after the xfs_sync_worker checks it but before the work is completed. The has caused crashes in the completion handler for the dummy transaction commited by xfs_sync_worker: PID: 27544 TASK: ffff88013544e040 CPU: 3 COMMAND: "kworker/3:0" #0 [ffff88016fdff930] machine_kexec at ffffffff810244e9 #1 [ffff88016fdff9a0] crash_kexec at ffffffff8108d053 #2 [ffff88016fdffa70] oops_end at ffffffff813ad1b8 #3 [ffff88016fdffaa0] no_context at ffffffff8102bd48 #4 [ffff88016fdffaf0] __bad_area_nosemaphore at ffffffff8102c04d #5 [ffff88016fdffb40] bad_area_nosemaphore at ffffffff8102c12e #6 [ffff88016fdffb50] do_page_fault at ffffffff813afaee #7 [ffff88016fdffc60] page_fault at ffffffff813ac635 [exception RIP: xlog_get_lowest_lsn+0x30] RIP: ffffffffa04a9910 RSP: ffff88016fdffd10 RFLAGS: 00010246 RAX: ffffc90014e48000 RBX: ffff88014d879980 RCX: ffff88014d879980 RDX: ffff8802214ee4c0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88016fdffd10 R8: ffff88014d879a80 R9: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff8802214ee400 R13: ffff88014d879980 R14: 0000000000000000 R15: ffff88022fd96605 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #8 [ffff88016fdffd18] xlog_state_do_callback at ffffffffa04aa186 [xfs] #9 [ffff88016fdffd98] xlog_state_done_syncing at ffffffffa04aa568 [xfs] Protect xfs_sync_worker by using the s_umount semaphore at the read level to provide exclusion with unmount while work is progressing. Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers --- fs/xfs/linux-2.6/xfs_sync.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c index ccb77cf..74ea9b1 100644 --- a/fs/xfs/linux-2.6/xfs_sync.c +++ b/fs/xfs/linux-2.6/xfs_sync.c @@ -470,21 +470,24 @@ xfs_sync_worker( * We shouldn't write/force the log if we are in the mount/unmount * process or on a read only filesystem. The workqueue still needs to be * active in both cases, however, because it is used for inode reclaim - * during these times. hence use the MS_ACTIVE flag to avoid doing - * anything in these periods. + * during these times. Use the s_umount semaphore to provide exclusion + * with unmount. */ - if (!(mp->m_super->s_flags & MS_ACTIVE) && - !(mp->m_flags & XFS_MOUNT_RDONLY)) { - /* dgc: errors ignored here */ - if (mp->m_super->s_frozen == SB_UNFROZEN && - xfs_log_need_covered(mp)) - error = xfs_fs_log_dummy(mp); - else - xfs_log_force(mp, 0); - error = xfs_qm_sync(mp, SYNC_TRYLOCK); - - /* start pushing all the metadata that is currently dirty */ - xfs_ail_push_all(mp->m_ail); + if (down_read_trylock(&mp->m_super->s_umount)) { + if (!(mp->m_super->s_flags & MS_ACTIVE) && + !(mp->m_flags & XFS_MOUNT_RDONLY)) { + /* dgc: errors ignored here */ + if (mp->m_super->s_frozen == SB_UNFROZEN && + xfs_log_need_covered(mp)) + error = xfs_fs_log_dummy(mp); + else + xfs_log_force(mp, 0); + error = xfs_qm_sync(mp, SYNC_TRYLOCK); + + /* start pushing all the metadata that is currently dirty */ + xfs_ail_push_all(mp->m_ail); + } + up_read(&mp->m_super->s_umount); } /* queue us up again */ -- 1.7.10 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs