mm: convert page_swap_flags to folio_swap_flags

The only caller already has a folio, so push the folio->page conversion
down a level.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

mm/swap.h

···
 struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
 			      struct vm_fault *vmf);
 
-static inline unsigned int page_swap_flags(struct page *page)
+static inline unsigned int folio_swap_flags(struct folio *folio)
 {
-	return page_swap_info(page)->flags;
+	return page_swap_info(&folio->page)->flags;
 }
 #else /* CONFIG_SWAP */
 struct swap_iocb;
···
 {
 }
 
-static inline unsigned int page_swap_flags(struct page *page)
+static inline unsigned int folio_swap_flags(struct folio *folio)
 {
 	return 0;
 }

mm/vmscan.c

···
 	 * but that will never affect SWP_FS_OPS, so the data_race
 	 * is safe.
 	 */
-	return !data_race(page_swap_flags(&folio->page) & SWP_FS_OPS);
+	return !data_race(folio_swap_flags(folio) & SWP_FS_OPS);
 }
 
 /*