One other change has been to plug a semantic hole in the error reporting of the lookup operation. In case of an error, the lookup operation in a leaf file system is supposed to return with the directory vnode in which it was looking locked. One potential problem with this is that it is possible that the error being returned resulted from not being able to reacquire the lock on the examined directory when looking up ``..''. In this scenario, the lookup routine has little choice but to return an error with the examined directory unlocked. It signals this behavior by setting the PDIRUNLOCK flag which is returned to the caller. When a layered file system is maintaining its own parallel locks (if the underlying file system did not export a lock structure), the layered file system must adjust its locks accordingly.