This involves converting all users of offs_page to offs_folio, but
it's worth it because we get rid of a lot of hidden calls to
compound_head().  We continue to use order-0 folios here, and convert
back to a struct page to call ntfs_bio_pages().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>