[PATCH, -stable RFC] xfs: fix periodic log flushing

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

There is a logic inversion in xfssyncd_worker() which means that the
log is not periodically forced or idled correctly. This means that
metadata changes aggregated in memory do not get flushed in a timely
manner, and hence if filesystem is not cleanly unmounted those
changes can be lost. This loss can manifest itself even hours after
the changes were made if the filesystem is left to idle without a
sync() occurring between the last modification and the
crash/shutdown occuring.

cc: <stable at vger.kerel.org> # 3.7, 3.6, 3.5
Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_sync.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

If people agree the fix is correct, I'll post it to the -stable
list for inclusion...

diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c
index 9500caf..7bf85e8 100644
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -400,7 +400,7 @@ xfs_sync_worker(
 	 * cancel_delayed_work_sync on this work queue before tearing down
 	 * the ail and the log in xfs_log_unmount.
 	 */
-	if (!(mp->m_super->s_flags & MS_ACTIVE) &&
+	if ((mp->m_super->s_flags & MS_ACTIVE) &&
 	    !(mp->m_flags & XFS_MOUNT_RDONLY)) {
 		/* dgc: errors ignored here */
 		if (mp->m_super->s_writers.frozen == SB_UNFROZEN &&