POSIX semantics dictate that once a file has been opened it may continue to be accessed by the process until closed, regardless of changes to permissions.
In PVFS2, the effect of permission changes on a file may or may not be immediately apparent to a client holding an open file descriptor. Because of the manner in which PVFS2 performs permission checking and file lookup, it is possible that a client may lose the ability to access a file that it has previously opened due to permission change, if for example the cached handle is lost and a lookup is performed again.