ocfs2/net: Add debug interface to o2net

This patch exposes o2net information via debugfs. The information includes
the list of sockets (sock_containers) as well as the list of outstanding
messages (send_tracking). Useful for o2dlm debugging.

(This patch is derived from an earlier one written by Zach Brown that
exposed the same information via /proc.)

[Mark: checkpatch fixes]

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Reviewed-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/cluster/nodemanager.c

@@ -959,7 +959,10 @@ static int __init init_o2nm(void)
 	cluster_print_version();
 
 	o2hb_init();
-	o2net_init();
+
+	ret = o2net_init();
+	if (ret)
+		goto out;
 
 	ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
 	if (!ocfs2_table_header) {