mm: Add arch_make_folio_accessible()

As a default implementation, call arch_make_page_accessible n times.
If an architecture can do better, it can override this.

Also move the default implementation of arch_make_page_accessible()
from gfp.h to mm.h.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

include/linux/gfp.h

@@ -520,12 +520,6 @@ static inline void arch_free_page(struct page *page, int order) { }
 #ifndef HAVE_ARCH_ALLOC_PAGE
 static inline void arch_alloc_page(struct page *page, int order) { }
 #endif
-#ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE
-static inline int arch_make_page_accessible(struct page *page)
-{
-	return 0;
-}
-#endif
 
 struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
 		nodemask_t *nodemask);

include/linux/mm.h

@@ -1734,6 +1734,29 @@ static inline size_t folio_size(struct folio *folio)
 	return PAGE_SIZE << folio_order(folio);
 }
 
+#ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE
+static inline int arch_make_page_accessible(struct page *page)
+{
+	return 0;
+}
+#endif
+
+#ifndef HAVE_ARCH_MAKE_FOLIO_ACCESSIBLE
+static inline int arch_make_folio_accessible(struct folio *folio)
+{
+	int ret;
+	long i, nr = folio_nr_pages(folio);
+
+	for (i = 0; i < nr; i++) {
+		ret = arch_make_page_accessible(folio_page(folio, i));
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+#endif
+
 /*
  * Some inline functions in vmstat.h depend on page_zone()
  */