mm: migrate_device: use more folio in migrate_device_finalize()

commit 58bf8c2 upstream.

Saves a couple of calls to compound_head() and remove last two callers of
putback_lru_page().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Reviewed-by: Vishal Moola (Oracle) <[email protected]>
Reviewed-by: Alistair Popple <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit e7a85efb873fa6f109c21ec99326b381f55e849e)

Author: Kefeng Wang

mm/migrate_device.c

@@ -814,42 +814,45 @@ void migrate_device_finalize(unsigned long *src_pfns,
 	unsigned long i;
 
 	for (i = 0; i < npages; i++) {
-		struct folio *dst, *src;
+		struct folio *dst = NULL, *src = NULL;
 		struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
 		struct page *page = migrate_pfn_to_page(src_pfns[i]);
 
+		if (newpage)
+			dst = page_folio(newpage);
+
 		if (!page) {
-			if (newpage) {
-				unlock_page(newpage);
-				put_page(newpage);
+			if (dst) {
+				folio_unlock(dst);
+				folio_put(dst);
 			}
 			continue;
 		}
 
-		if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE) || !newpage) {
-			if (newpage) {
-				unlock_page(newpage);
-				put_page(newpage);
+		src = page_folio(page);
+
+		if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE) || !dst) {
+			if (dst) {
+				folio_unlock(dst);
+				folio_put(dst);
 			}
-			newpage = page;
+			dst = src;
 		}
 
-		src = page_folio(page);
-		dst = page_folio(newpage);
 		remove_migration_ptes(src, dst, false);
 		folio_unlock(src);
 
-		if (is_zone_device_page(page))
-			put_page(page);
+		if (folio_is_zone_device(src))
+			folio_put(src);
 		else
-			putback_lru_page(page);
+			folio_putback_lru(src);
 
-		if (newpage != page) {
-			unlock_page(newpage);
-			if (is_zone_device_page(newpage))
-				put_page(newpage);
+		if (dst != src) {
+			folio_unlock(dst);
+			if (folio_is_zone_device(dst))
+				folio_put(dst);
 			else
-				putback_lru_page(newpage);
+				folio_putback_lru(dst);
 		}
 	}
 }