dax_entry_order
count = 1UL << dax_entry_order(entry);
if (dax_entry_order(entry) < order)
int order = dax_entry_order(entry);
WARN_ON_ONCE(dax_entry_order(entry) != folio_order(folio));
mapping->nrpages -= 1UL << dax_entry_order(entry);
mapping->nrpages -= 1UL << dax_entry_order(entry);