These are the folio equivalent of memcpy_to_page() and memcpy_from_page(). Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> --- include/linux/highmem.h | 44 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 68da30625a6c..0280f57d4744 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -439,6 +439,50 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len) kunmap_local(addr); } +static inline void memcpy_from_folio(char *to, struct folio *folio, + size_t offset, size_t len) +{ + VM_BUG_ON(offset + len > folio_size(folio)); + + do { + char *from = kmap_local_folio(folio, offset); + size_t chunk = len; + + if (folio_test_highmem(folio) && + (chunk > (PAGE_SIZE - offset_in_page(offset)))) + chunk = PAGE_SIZE - offset_in_page(offset); + memcpy(to, from, len); + kunmap_local(from); + + from += chunk; + offset += chunk; + len -= chunk; + } while (len > 0); +} + +static inline void memcpy_to_folio(struct folio *folio, size_t offset, + const char *from, size_t len) +{ + VM_BUG_ON(offset + len > folio_size(folio)); + + do { + char *to = kmap_local_folio(folio, offset); + size_t chunk = len; + + if (folio_test_highmem(folio) && + (chunk > (PAGE_SIZE - offset_in_page(offset)))) + chunk = PAGE_SIZE - offset_in_page(offset); + memcpy(to, from, len); + kunmap_local(to); + + from += chunk; + offset += chunk; + len -= chunk; + } while (len > 0); + + flush_dcache_folio(folio); +} + /** * memcpy_from_file_folio - Copy some bytes from a file folio. * @to: The destination buffer. -- 2.39.2