rfsdelta is a kernel module for the Linux 2.6 series that collects all filesystem inode changes (recursively) and reports them to a userspace process. It is similar to inotify, dnotify (but provides recursive notification, and only a single watcher process is allowed), fschange, fsevent, and rlocate (but also reports unlink(), rmdir(), and st_*). rfsdelta was based on the kernel module shipped with rlocate 0.5.5.