The utimensat() man page says: "To set both a birth time and a modification time, two calls are required; the first to set the birth time and the second to set the (presumably newer) modification time. Ideally a new system call will be added that allows the setting of all three times at once." Such a newer system call would indeed simplify changing the birthtime of a file, which currently is rather complicated to edit. I can't find any existing bug for this, so thought I'd create one...