[RFC,v3,02/21] mm/zsmalloc: add utility functions for zsdesc

Commit Message

Hyeonggon Yoo Nov. 30, 2023, 10:12 a.m. UTC

Introduce basic utility functions for zsdesc to avoid directly accessing
fields of struct page. More helpers will be defined later.

zsdesc_page() is defined with _Generic to preserve constness.
page_zsdesc() does not call compound_head() because zsdesc is always
a base page.

Signed-off-by: Hyeonggon Yoo <[e-mail]>
---
 mm/zsmalloc.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

Patch

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 60ce2a4dfeeb..47df9103787e 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -274,6 +274,39 @@  ZSDESC_MATCH(_refcount, __page_refcount);
 #undef ZSDESC_MATCH
 static_assert(sizeof(struct zsdesc) <= sizeof(struct page));
 
+#define zsdesc_page(zdesc) (_Generic((zdesc),				\
+		const struct zsdesc *:	(const struct page *)zdesc,	\
+		struct zsdesc *:	(struct page *)zdesc))
+
+static inline struct zsdesc *page_zsdesc(struct page *page)
+{
+	return (struct zsdesc *)page;
+}
+
+static inline unsigned long zsdesc_pfn(const struct zsdesc *zsdesc)
+{
+	return page_to_pfn(zsdesc_page(zsdesc));
+}
+
+static inline struct zsdesc *pfn_zsdesc(unsigned long pfn)
+{
+	return page_zsdesc(pfn_to_page(pfn));
+}
+
+static inline void zsdesc_get(struct zsdesc *zsdesc)
+{
+	struct folio *folio = (struct folio *)zsdesc;
+
+	folio_get(folio);
+}
+
+static inline void zsdesc_put(struct zsdesc *zsdesc)
+{
+	struct folio *folio = (struct folio *)zsdesc;
+
+	folio_put(folio);
+}
+
 struct zspage {
 	struct {
 		unsigned int huge:HUGE_BITS;