[PATCH 1/3] mm: Add folio_movable_ops()

["Vishal Moola (Oracle)" <vishal.moola@gmail.com>]

folio_movable_ops() does the same as page_movable_ops() except uses
folios instead of pages. This function will help make folio conversions
in mm/migrate.c more readable.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/migrate.h | 9 +++++++++
 mm/migrate.c            | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 3ef77f52a4f0..bdff950a8bb4 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -122,6 +122,15 @@ static inline bool folio_test_movable(struct folio *folio)
 	return PageMovable(&folio->page);
 }
 
+static inline
+const struct movable_operations *folio_movable_ops(struct folio *folio)
+{
+	VM_BUG_ON(!__folio_test_movable(folio));
+
+	return (const struct movable_operations *)
+		((unsigned long)folio->mapping - PAGE_MAPPING_MOVABLE);
+}
+
 static inline
 const struct movable_operations *page_movable_ops(struct page *page)
 {
diff --git a/mm/migrate.c b/mm/migrate.c
index a4d3fc65085f..4c1776445c74 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -973,7 +973,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
 			goto out;
 		}
 
-		mops = page_movable_ops(&src->page);
+		mops = folio_movable_ops(src);
 		rc = mops->migrate_page(&dst->page, &src->page, mode);
 		WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
 				!folio_test_isolated(src));
-- 
2.38.1