mm/migrate: add folio_movable_ops()

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

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Vishal Moola (Oracle) <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 9 insertions, 0 deletions

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
@@ -123,6 +123,15 @@ static inline bool folio_test_movable(struct folio *folio)
 }
 
 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)
 {
 	VM_BUG_ON(!__PageMovable(page));