[RFC PATCH 2/9] mm: add page_type value helper

[Huan Yang]

Add two helper functions __SetPageXXXValue and __GetPageXXXValue to
assist in assigning values to the specified page_type. Since the current
page_type value is not supported on large folio, only the page version
of the helper functions is provided.

Signed-off-by: Huan Yang <link@xxxxxxxx>
---
 include/linux/page-flags.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 3c7103c2eee4..52c9435079d5 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -1024,6 +1024,23 @@ static __always_inline void __ClearPage##uname(struct page *page)	\
 		return;							\
 	VM_BUG_ON_PAGE(!Page##uname(page), page);			\
 	page->page_type = UINT_MAX;					\
+}									\
+static __always_inline void __PageSet##uname##Value(struct page *page,	\
+						    unsigned int value) \
+{									\
+	if (!Page##uname(page))						\
+		return;							\
+	if (unlikely(value > (PAGE_TYPE_MASK)))				\
+		return;							\
+	WRITE_ONCE(page->page_type, (unsigned int)PGTY_##lname		\
+				    << PAGE_TYPE_SHIFT | value);	\
+}									\
+static __always_inline unsigned int __PageGet##uname##Value(		\
+				    struct page *page)			\
+{									\
+	if (!Page##uname(page))						\
+		return 0;						\
+	return READ_ONCE(page->page_type) & PAGE_TYPE_MASK;		\
 }
 
 /*
-- 
2.34.1