performance improvements
diff --git a/BUGS b/BUGS
new file mode 100644
index 0000000..df5f428
--- /dev/null
+++ b/BUGS
@@ -0,0 +1,4 @@
+- It is allowed to mount a directory on a non-directory.
+
+- When a non-directory is mounted the root inode is not filled in, only at
+  the first getattr