mm: add folio_mapping_flags()

This is the equivalent of PageMappingFlags and is needed for converting
mm/migrate.c to folios.

Link: https://lkml.kernel.org/r/20220504182857.4013401-25-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/page-flags.h

@@ -650,6 +650,11 @@ __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
 #define PAGE_MAPPING_KSM	(PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 #define PAGE_MAPPING_FLAGS	(PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
 
+static __always_inline bool folio_mapping_flags(struct folio *folio)
+{
+	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
+}
+
 static __always_inline int PageMappingFlags(struct page *page)
 {
 	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;