Constant fanotify::low_level::FAN_ONDIR

pub const FAN_ONDIR: u64 = 0x4000_0000;

Create events for directories—for example, when opendir(3), readdir(3) (but see BUGS), and closedir(3) are called.
Without this flag, events are created only for files.
In the context of directory entry events, such as FAN_CREATE,FAN_DELETE, FAN_MOVED_FROM, and FAN_MOVED_TO, specifying the flag FAN_ONDIR is required in order to create events when subdirectory entries are modified (i.e., mkdir(2)/rmdir(2)).