On Wed, Dec 22, 2021 at 10:55:20PM -0800, Christoph Hellwig wrote: > On Wed, Dec 08, 2021 at 04:22:14AM +0000, Matthew Wilcox (Oracle) wrote: > > +static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset, > > + size_t bytes, struct iov_iter *i) > > +{ > > + return copy_page_to_iter((struct page *)folio, offset, bytes, i); > > +} > > I think we had this 2 or three series ago, but these open coded casts > are a bad idea. I think we need a proper and well documented helper for > them. I don't want to see casts between folio & page in most code, but I think having it in this kind of helper is fine. It literally exists in order to document that the callee handles folios correctly.