A method for controlling access to a file system having data elements, including the steps of maintaining a record of respective actual accesses by users of the file system to the data elements, defining a proposed removal of a set of the users from a superset of the users, wherein members of the superset have common access privileges to a portion of the data elements, and wherein following an implementation of the proposed removal, members of the set retain respective proposed residual access permissions, ascertaining, prior to the implementation of the proposed removal, that at least one of the respective actual accesses are disallowed to the members of the set, or to non-members of the set having actual access profiles which are similar to the actual access profiles of the members of the set, by the respective proposed residual access permissions, and generating an error indication, responsively to the ascertaining.