US Patent 8239351 Methods and systems for managing permissions data

Methods, systems and computer readable media which use permissions checking when deciding whether to allow access to a file are described. In one exemplary embodiment, a method includes receiving a notification of a change of permissions of a directory in a hierarchical file system and determining, in response to the notification, whether to update partially a permissions cache which is used in screening access based on permissions, such as access to search results. The determining may include a comparison of an identifier of the directory to a data structure of cached directories which have files represented in the permissions cache.