Abstract: Aspects of the subject matter described herein relate to directory oplocks. In aspects, a file system filter is inserted in a filter stack between requesters of directory oplocks and a file system that stores file system objects. The file system filter receives requests for directory oplocks and subsequently monitors for requests to access file system objects that are inconsistent with the directory oplocks. To provide directory oplock mechanisms, the file system filter may use alternate data streams if provided by the file system or may independently maintain information usable to maintain and release directory oplocks. A directory oplock may affect ancestors and descendants of the directory depending on constraints imposed by the oplock.