pub fn padding_span(len: usize, alignment: usize) -> Option<usize>Expand description
On-disk size of the padding record needed to bring len up to an
alignment boundary, or None when len is already aligned.
A gap narrower than a record header cannot hold one, so the span is
extended by a whole extra block. The result is always either 0 or at
least MIN_PADDING_RECORD_SIZE, and len + span is always aligned.