[PATCH rfc 3/9] mm: migrate: remove migrate_folio_extra()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

Convert migrate_folio_extra() to __migrate_folio() which will be used
by migrate_folio() and filemap_migrate_folio(), also directly call
folio_migrate_mapping() in __migrate_device_pages() to simplify code.

Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
 include/linux/migrate.h |  2 --
 mm/migrate.c            | 32 +++++++++++---------------------
 mm/migrate_device.c     | 13 +++++++------
 3 files changed, 18 insertions(+), 29 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 2ce13e8a309b..517f70b70620 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -63,8 +63,6 @@ extern const char *migrate_reason_names[MR_TYPES];
 #ifdef CONFIG_MIGRATION
 
 void putback_movable_pages(struct list_head *l);
-int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
-		struct folio *src, enum migrate_mode mode, int extra_count);
 int migrate_folio(struct address_space *mapping, struct folio *dst,
 		struct folio *src, enum migrate_mode mode);
 int migrate_pages(struct list_head *l, new_folio_t new, free_folio_t free,
diff --git a/mm/migrate.c b/mm/migrate.c
index cdae25b7105f..a51ceebbe3b1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -655,22 +655,24 @@ EXPORT_SYMBOL(folio_migrate_copy);
  *                    Migration functions
  ***********************************************************/
 
-int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
-		struct folio *src, enum migrate_mode mode, int extra_count)
+static int __migrate_folio(struct address_space *mapping, struct folio *dst,
+			   struct folio *src, enum migrate_mode mode,
+			   void *src_private)
 {
 	int rc;
 
-	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
-
-	rc = folio_migrate_mapping(mapping, dst, src, extra_count);
-
+	rc = folio_migrate_mapping(mapping, dst, src, 0);
 	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 
+	if (src_private)
+		folio_attach_private(dst, folio_detach_private(src));
+
 	if (mode != MIGRATE_SYNC_NO_COPY)
 		folio_migrate_copy(dst, src);
 	else
 		folio_migrate_flags(dst, src);
+
 	return MIGRATEPAGE_SUCCESS;
 }
 
@@ -689,7 +691,8 @@ int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
 int migrate_folio(struct address_space *mapping, struct folio *dst,
 		struct folio *src, enum migrate_mode mode)
 {
-	return migrate_folio_extra(mapping, dst, src, mode, 0);
+	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
+	return __migrate_folio(mapping, dst, src, mode, NULL);
 }
 EXPORT_SYMBOL(migrate_folio);
 
@@ -843,20 +846,7 @@ EXPORT_SYMBOL_GPL(buffer_migrate_folio_norefs);
 int filemap_migrate_folio(struct address_space *mapping,
 		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
-	int ret;
-
-	ret = folio_migrate_mapping(mapping, dst, src, 0);
-	if (ret != MIGRATEPAGE_SUCCESS)
-		return ret;
-
-	if (folio_get_private(src))
-		folio_attach_private(dst, folio_detach_private(src));
-
-	if (mode != MIGRATE_SYNC_NO_COPY)
-		folio_migrate_copy(dst, src);
-	else
-		folio_migrate_flags(dst, src);
-	return MIGRATEPAGE_SUCCESS;
+	return __migrate_folio(mapping, dst, src, mode, folio_get_private(src));
 }
 EXPORT_SYMBOL_GPL(filemap_migrate_folio);
 
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index d49a48d87d72..bea71d69295a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -695,7 +695,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 		struct page *page = migrate_pfn_to_page(src_pfns[i]);
 		struct address_space *mapping;
 		struct folio *newfolio, *folio;
-		int r;
+		int r, extra_cnt = 0;
 
 		if (!newpage) {
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
@@ -757,14 +757,15 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 			continue;
 		}
 
+		BUG_ON(folio_test_writeback(folio));
+
 		if (migrate && migrate->fault_page == page)
-			r = migrate_folio_extra(mapping, newfolio, folio,
-						MIGRATE_SYNC_NO_COPY, 1);
-		else
-			r = migrate_folio(mapping, newfolio, folio,
-					  MIGRATE_SYNC_NO_COPY);
+			extra_cnt = 1;
+		r = folio_migrate_mapping(mapping, newfolio, folio, extra_cnt);
 		if (r != MIGRATEPAGE_SUCCESS)
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+		else
+			folio_migrate_flags(newfolio, folio);
 	}
 
 	if (notified)
-- 
2.27.0