ceph: build cleanly without CONFIG_DEBUG_FS

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/osd_client.h b/fs/ceph/osd_client.h
index 9a4addf..766c8dc 100644
--- a/fs/ceph/osd_client.h
+++ b/fs/ceph/osd_client.h
@@ -83,7 +83,9 @@
 	struct rb_root         requests;      /* pending requests */
 	int                    num_requests;
 	struct delayed_work    timeout_work;
+#ifdef CONFIG_DEBUG_FS
 	struct dentry 	       *debugfs_file;
+#endif
 
 	mempool_t              *req_mempool;