iov_iter: Add copy_folio_to_iter()

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>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 6350354f97e90f08b0d64f66c349f9224bc1a2f9..43321dbebba8160d75a4d386126fe0ef61f4c7a1 100644 (file)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -7,6 +7,7 @@
 
 #include <linux/kernel.h>
 #include <linux/thread_info.h>
+#include <linux/mm_types.h>
 #include <uapi/linux/uio.h>
 
 struct page;
@@ -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(&folio->page, offset, bytes, i);
+}
+
 static __always_inline __must_check
 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 {