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
