mm/folio-compat: Remove migration compatibility functions

migrate_page_move_mapping(), migrate_page_copy() and migrate_page_states()
are all now unused after converting all the filesystems from
aops->migratepage() to aops->migrate_folio().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

include/linux/migrate.h

@@ -70,12 +70,8 @@ extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
 extern struct page *alloc_migration_target(struct page *page, unsigned long private);
 extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
 
-extern void migrate_page_states(struct page *newpage, struct page *page);
-extern void migrate_page_copy(struct page *newpage, struct page *page);
 int migrate_huge_page_move_mapping(struct address_space *mapping,
 		struct folio *dst, struct folio *src);
-extern int migrate_page_move_mapping(struct address_space *mapping,
-		struct page *newpage, struct page *page, int extra_count);
 void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep,
 				spinlock_t *ptl);
 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
@@ -96,13 +92,6 @@ static inline struct page *alloc_migration_target(struct page *page,
 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	{ return -EBUSY; }
 
-static inline void migrate_page_states(struct page *newpage, struct page *page)
-{
-}
-
-static inline void migrate_page_copy(struct page *newpage,
-				     struct page *page) {}
-
 static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 				  struct folio *dst, struct folio *src)
 {

mm/folio-compat.c

@@ -51,28 +51,6 @@ void mark_page_accessed(struct page *page)
 }
 EXPORT_SYMBOL(mark_page_accessed);
 
-#ifdef CONFIG_MIGRATION
-int migrate_page_move_mapping(struct address_space *mapping,
-		struct page *newpage, struct page *page, int extra_count)
-{
-	return folio_migrate_mapping(mapping, page_folio(newpage),
-					page_folio(page), extra_count);
-}
-EXPORT_SYMBOL(migrate_page_move_mapping);
-
-void migrate_page_states(struct page *newpage, struct page *page)
-{
-	folio_migrate_flags(page_folio(newpage), page_folio(page));
-}
-EXPORT_SYMBOL(migrate_page_states);
-
-void migrate_page_copy(struct page *newpage, struct page *page)
-{
-	folio_migrate_copy(page_folio(newpage), page_folio(page));
-}
-EXPORT_SYMBOL(migrate_page_copy);
-#endif
-
 bool set_page_writeback(struct page *page)
 {
 	return folio_start_writeback(page_folio(page));

mm/ksm.c

@@ -712,7 +712,7 @@ static struct page *get_ksm_page(struct stable_node *stable_node,
 	 * however, it might mean that the page is under page_ref_freeze().
 	 * The __remove_mapping() case is easy, again the node is now stale;
 	 * the same is in reuse_ksm_page() case; but if page is swapcache
-	 * in migrate_page_move_mapping(), it might still be our page,
+	 * in folio_migrate_mapping(), it might still be our page,
 	 * in which case it's essential to keep the node.
 	 */
 	while (!get_page_unless_zero(page)) {