ceph: build cleanly without CONFIG_DEBUG_FS

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index 9edbad3..9b20206 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -8,6 +8,8 @@
 #include "super.h"
 #include "mds_client.h"
 
+#ifdef CONFIG_DEBUG_FS
+
 /*
  * Implement /sys/kernel/debug/ceph fun
  *
@@ -423,3 +425,24 @@
 	debugfs_remove(client->debugfs_dir);
 }
 
+#else  // CONFIG_DEBUG_FS
+
+int __init ceph_debugfs_init(void)
+{
+	return 0;
+}
+
+void ceph_debugfs_cleanup(void)
+{
+}
+
+int ceph_debugfs_client_init(struct ceph_client *client)
+{
+	return 0;
+}
+
+void ceph_debugfs_client_cleanup(struct ceph_client *client)
+{
+}
+
+#endif  // CONFIG_DEBUG_FS