ocfs2: Stop orphan scan as early as possible during umount

Currently if the orphan scan fires a tick before the user issues the umount,
the umount will wait for the queued orphan scan tasks to complete.

This patch makes the umount stop the orphan scan as early as possible so as
to reduce the probability of the queued tasks slowing down the umount.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 18c1d9e..60e8950 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -154,6 +154,11 @@
 #endif
 };
 
+enum ocfs2_orphan_scan_state {
+	ORPHAN_SCAN_ACTIVE,
+	ORPHAN_SCAN_INACTIVE
+};
+
 struct ocfs2_orphan_scan {
 	struct mutex 		os_lock;
 	struct ocfs2_super 	*os_osb;
@@ -162,6 +167,7 @@
 	struct timespec		os_scantime;  /* time this node ran the scan */
 	u32			os_count;      /* tracks node specific scans */
 	u32  			os_seqno;       /* tracks cluster wide scans */
+	atomic_t		os_state;              /* ACTIVE or INACTIVE */
 };
 
 struct ocfs2_dlm_debug {