ceph: build cleanly without CONFIG_DEBUG_FS

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index f566e9c..0751b82 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -256,7 +256,9 @@
 	spinlock_t        cap_dirty_lock;   /* protects above items */
 	wait_queue_head_t cap_flushing_wq;
 
+#ifdef CONFIG_DEBUG_FS
 	struct dentry 	  *debugfs_file;
+#endif
 
 	spinlock_t	  dentry_lru_lock;
 	struct list_head  dentry_lru;