ocfs2: Abstract out node number queries.

ocfs2 asks the cluster stack for the local node's node number for two
reasons; to fill the slot map and to print it. While the slot map isn't
necessary for userspace cluster stacks, the printing is very nice for
debugging. Thus we add ocfs2_cluster_this_node() as a generic API to get
this value. It is anticipated that the slot map will not be used under a
userspace cluster stack, so validity checks of the node num only need to
exist in the slot map code. Otherwise, it just gets used and printed as an
opaque value.

[ Fixed up some "int" versus "unsigned int" issues and made osb->node_num
  truly opaque. --Mark ]

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/stackglue.c

@@ -25,6 +25,8 @@
 #include <linux/fs.h>
 
 #include "cluster/masklog.h"
+#include "cluster/nodemanager.h"
+
 #include "stackglue.h"
 
 static struct ocfs2_locking_protocol *lproto;
@@ -371,6 +373,21 @@ int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn)
 	return 0;
 }
 
+int ocfs2_cluster_this_node(unsigned int *node)
+{
+	int node_num;
+
+	node_num = o2nm_this_node();
+	if (node_num == O2NM_INVALID_NODE_NUM)
+		return -ENOENT;
+
+	if (node_num >= O2NM_MAX_NODES)
+		return -EOVERFLOW;
+
+	*node = node_num;
+	return 0;
+}
+
 void o2cb_get_stack(struct ocfs2_locking_protocol *proto)
 {
 	BUG_ON(proto == NULL);