[PATCH 4/6] migrate: Expand the use of folio in __migrate_device_pages()

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Removes a few calls to compound_head() and a call to page_mapping().

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/migrate_device.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index a68616c1965f..aecc71972a87 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -692,6 +692,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 		struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
 		struct page *page = migrate_pfn_to_page(src_pfns[i]);
 		struct address_space *mapping;
+		struct folio *folio;
 		int r;
 
 		if (!newpage) {
@@ -726,15 +727,12 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 			continue;
 		}
 
-		mapping = page_mapping(page);
+		folio = page_folio(page);
+		mapping = folio_mapping(folio);
 
 		if (is_device_private_page(newpage) ||
 		    is_device_coherent_page(newpage)) {
 			if (mapping) {
-				struct folio *folio;
-
-				folio = page_folio(page);
-
 				/*
 				 * For now only support anonymous memory migrating to
 				 * device private or coherent memory.
@@ -757,11 +755,10 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 
 		if (migrate && migrate->fault_page == page)
 			r = migrate_folio_extra(mapping, page_folio(newpage),
-						page_folio(page),
-						MIGRATE_SYNC_NO_COPY, 1);
+						folio, MIGRATE_SYNC_NO_COPY, 1);
 		else
 			r = migrate_folio(mapping, page_folio(newpage),
-					page_folio(page), MIGRATE_SYNC_NO_COPY);
+					folio, MIGRATE_SYNC_NO_COPY);
 		if (r != MIGRATEPAGE_SUCCESS)
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
 	}
-- 
2.43.0