This definitely doesn't include support for large folios; there
are all kinds of assumptions about the number of buffers attached
to a folio.  But it does remove several calls to compound_head().
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-24-willy@infradead.orgSigned-off-by: NTheodore Ts'o <tytso@mit.edu>