ocfs2: live heartbeat depends on the local node configuration

Removing the local node configuration out from underneath a running
heartbeat is "bad".  Provide an API in the ocfs2 nodemanager to request
a configfs dependancy on the local node, then use it in heartbeat.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/cluster/heartbeat.c

@@ -1693,9 +1693,18 @@ static int o2hb_region_get(const char *region_uuid)
 		ret = -ENOENT;
 	spin_unlock(&o2hb_live_lock);
 
-	if (!ret)
+	if (ret)
+		goto out;
+
+	ret = o2nm_depend_this_node();
+	if (ret)
+		goto out;
+
 	ret = o2nm_depend_item(&reg->hr_item);
+	if (ret)
+		o2nm_undepend_this_node();
 
+out:
 	return ret;
 }
 
@@ -1709,8 +1718,10 @@ static void o2hb_region_put(const char *region_uuid)
 
 	spin_unlock(&o2hb_live_lock);
 
-	if (reg)
+	if (reg) {
 		o2nm_undepend_item(&reg->hr_item);
+		o2nm_undepend_this_node();
+	}
 }
 
 int o2hb_register_callback(const char *region_uuid,

fs/ocfs2/cluster/nodemanager.c

@@ -910,6 +910,36 @@ void o2nm_undepend_item(struct config_item *item)
 	configfs_undepend_item(&o2nm_cluster_group.cs_subsys, item);
 }
 
+int o2nm_depend_this_node(void)
+{
+	int ret = 0;
+	struct o2nm_node *local_node;
+
+	local_node = o2nm_get_node_by_num(o2nm_this_node());
+	if (!local_node) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = o2nm_depend_item(&local_node->nd_item);
+	o2nm_node_put(local_node);
+
+out:
+	return ret;
+}
+
+void o2nm_undepend_this_node(void)
+{
+	struct o2nm_node *local_node;
+
+	local_node = o2nm_get_node_by_num(o2nm_this_node());
+	BUG_ON(!local_node);
+
+	o2nm_undepend_item(&local_node->nd_item);
+	o2nm_node_put(local_node);
+}
+
+
 static void __exit exit_o2nm(void)
 {
 	if (ocfs2_table_header)

fs/ocfs2/cluster/nodemanager.h

@@ -79,5 +79,7 @@ void o2nm_node_put(struct o2nm_node *node);
 
 int o2nm_depend_item(struct config_item *item);
 void o2nm_undepend_item(struct config_item *item);
+int o2nm_depend_this_node(void);
+void o2nm_undepend_this_node(void);
 
 #endif /* O2CLUSTER_NODEMANAGER_H */