Convert function to use a folio_batch instead of pagevec.  This is in
preparation for the removal of find_get_pages_range_tag().

Also some minor renaming for consistency.

Link: https://lkml.kernel.org/r/20230104211448.4804-9-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>