The Sun VFS filesystem interface is the most widely used generic filesystem interface. Of the interfaces examined, it creates the cleanest separation between the filesystem-independent and -dependent layers and data structures. It has several flaws, but it is felt that certain changes in the interface can ameliorate most of them. The interface proposed here includes those changes. The proposed interface is now being implemented by the Computer Systems Research Group at Berkeley. If the design succeeds in improving the flexibility and performance of the filesystem layering, it will be advanced as a model interface.