| Message ID | 20211208042256.1923824-7-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Folios for 5.17 | expand |
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.
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.
diff --git a/include/linux/uio.h b/include/linux/uio.h index 6350354f97e9..8479cf46b5b1 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -10,6 +10,7 @@ #include <uapi/linux/uio.h> struct page; +struct folio; struct pipe_inode_info; struct kvec { @@ -146,6 +147,12 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i); +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); +} + static __always_inline __must_check size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) {
This wrapper around copy_page_to_iter() works because copy_page_to_iter() handles compound pages correctly. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- include/linux/uio.h | 7 +++++++ 1 file changed, 7 insertions(+)