  The remote procedure call (a.k.a. RPC) latency becomes increasingly
significant in a distributed file system. We propose BuffetFS, a user-level
file system that optimizes I/O performance by eliminating the RPCs caused by
\texttt{open()} operation. By leveraging \texttt{open()} from file servers to
clients, BuffetFS can restrain the procedure calls for permission checks
locally, hence avoid RPCs during the initial stage to access a file. BuffetFS
can further reduce response time when users are accessing a large number of
small files. We implement a BuffetFS prototype and integrate it into a storage
cluster. Our preliminary evaluation results show that BuffetFS can offer up to
70\% performance gain compared to the Lustre file system.
