+ * The hacking way of using bvec table as page pointer array is safe
+ * even after multipage bvec is introduced because that space can be
+ * thought as unused by bio_add_page().

I'm not sure what value this comment adds.

Note that once we have multi-page biovecs this could should change
to take advantage of multipage biovecs, so adding a comment before
that doesn't seem too helpful.