[XFS] Write log dummy record when freezing filesystem

SGI-PV: 945483
SGI-Modid: xfs-linux-melb:xfs-kern:202638a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index d1236d6..163031c 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -540,6 +540,32 @@
 	return(0);
 }
 
+void
+xfs_fs_log_dummy(xfs_mount_t *mp)
+{
+	xfs_trans_t *tp;
+	xfs_inode_t *ip;
+
+
+	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
+	atomic_inc(&mp->m_active_trans);
+	if (xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0)) {
+		xfs_trans_cancel(tp, 0);
+		return;
+	}
+
+	ip = mp->m_rootip;
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+	xfs_trans_ihold(tp, ip);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	xfs_trans_set_sync(tp);
+	xfs_trans_commit(tp, 0, NULL);
+
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+}
+
 int
 xfs_fs_goingdown(
 	xfs_mount_t	*mp,