1. A method comprising: receiving a file operation request from a process; a computer system performing a census of instances of a file applicable to said file operation request to populate a data structure, wherein said data structure comprises a listing of said instances, and said data structure further comprises characteristics for a first instance from among said instances and characteristics for a second instance from among said instances; determining whether the first and second instances are to be made visible to said process, wherein said determining comprises determining whether said file operation request is acceptable according to a rule, and if said file operation request is acceptable, determining whether the first and second instances are to be made visible to said process by comparing characteristics of said first and second instances with characteristics of said rule, and said rule corresponds to said process; making said first instance non-visible to said process on the basis of a determination that said first instance does not satisfy said rule; and selecting for performance of said file operation request said second instance, wherein said selecting comprises selecting said second instance responsive to ascertaining that said second instance resides in a data layer, selecting said second instance responsive to ascertaining that said second instance resides in an owner layer for said process, selecting said second instance responsive to ascertaining that said second instance resides in a base file system for a client in which said process is a native process, and selecting said second instance responsive to ascertaining that said second instance resides in a non-owner application layer and another rule for resolving conflicts indicates said selecting.