mm/swap: convert __delete_from_swap_cache() to a folio

All callers now have a folio, so convert the entire function to operate
on folios.

Link: https://lkml.kernel.org/r/20220617175020.717127-23-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap.h

@@ -36,7 +36,7 @@ bool add_to_swap(struct folio *folio);
 void *get_shadow_from_swap_cache(swp_entry_t entry);
 int add_to_swap_cache(struct page *page, swp_entry_t entry,
 		      gfp_t gfp, void **shadowp);
-void __delete_from_swap_cache(struct page *page,
+void __delete_from_swap_cache(struct folio *folio,
 			      swp_entry_t entry, void *shadow);
 void delete_from_swap_cache(struct folio *folio);
 void clear_shadow_from_swap_cache(int type, unsigned long begin,
@@ -135,7 +135,7 @@ static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 	return -1;
 }
 
-static inline void __delete_from_swap_cache(struct page *page,
+static inline void __delete_from_swap_cache(struct folio *folio,
 					swp_entry_t entry, void *shadow)
 {
 }

mm/swap_state.c

@@ -133,31 +133,32 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry,
 }
 
 /*
- * This must be called only on pages that have
+ * This must be called only on folios that have
  * been verified to be in the swap cache.
  */
-void __delete_from_swap_cache(struct page *page,
+void __delete_from_swap_cache(struct folio *folio,
 			swp_entry_t entry, void *shadow)
 {
 	struct address_space *address_space = swap_address_space(entry);
-	int i, nr = thp_nr_pages(page);
+	int i;
+	long nr = folio_nr_pages(folio);
 	pgoff_t idx = swp_offset(entry);
 	XA_STATE(xas, &address_space->i_pages, idx);
 
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
-	VM_BUG_ON_PAGE(PageWriteback(page), page);
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+	VM_BUG_ON_FOLIO(!folio_test_swapcache(folio), folio);
+	VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio);
 
 	for (i = 0; i < nr; i++) {
 		void *entry = xas_store(&xas, shadow);
-		VM_BUG_ON_PAGE(entry != page, entry);
-		set_page_private(page + i, 0);
+		VM_BUG_ON_FOLIO(entry != folio, folio);
+		set_page_private(folio_page(folio, i), 0);
 		xas_next(&xas);
 	}
-	ClearPageSwapCache(page);
+	folio_clear_swapcache(folio);
 	address_space->nrpages -= nr;
-	__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
-	__mod_lruvec_page_state(page, NR_SWAPCACHE, -nr);
+	__node_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
+	__lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr);
 }
 
 /**
@@ -233,7 +234,7 @@ void delete_from_swap_cache(struct folio *folio)
 	struct address_space *address_space = swap_address_space(entry);
 
 	xa_lock_irq(&address_space->i_pages);
-	__delete_from_swap_cache(&folio->page, entry, NULL);
+	__delete_from_swap_cache(folio, entry, NULL);
 	xa_unlock_irq(&address_space->i_pages);
 
 	put_swap_page(&folio->page, entry);

mm/vmscan.c

@@ -1329,7 +1329,7 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
 		mem_cgroup_swapout(folio, swap);
 		if (reclaimed && !mapping_exiting(mapping))
 			shadow = workingset_eviction(folio, target_memcg);
-		__delete_from_swap_cache(&folio->page, swap, shadow);
+		__delete_from_swap_cache(folio, swap, shadow);
 		xa_unlock_irq(&mapping->i_pages);
 		put_swap_page(&folio->page, swap);
 	} else {