From: Zi Yan <ziy@xxxxxxxxxx>
It is a preparation patch. The added MIGRATE_NO_COPY will be used by the
following patches to implement batched page copy functions by skipping
folio copy process in __migrate_folio() and copying folios in one shot
at the end.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Shivank Garg <shivankg@xxxxxxx>
---
include/linux/migrate_mode.h | 2 ++
mm/migrate.c | 8 +++++---
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index 265c4328b36a..9af6c949a057 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -7,11 +7,13 @@
* on most operations but not ->writepage as the potential stall time
* is too significant
* MIGRATE_SYNC will block when migrating pages
+ * MIGRATE_NO_COPY will not copy page content
*/
enum migrate_mode {
MIGRATE_ASYNC,
MIGRATE_SYNC_LIGHT,
MIGRATE_SYNC,
+ MIGRATE_NO_COPY,
};
enum migrate_reason {
diff --git a/mm/migrate.c b/mm/migrate.c
index ce7ddc56e878..0d40ac069cea 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -757,9 +757,11 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
if (folio_ref_count(src) != expected_count)
return -EAGAIN;
- rc = folio_mc_copy(dst, src);
- if (unlikely(rc))
- return rc;
+ if (mode != MIGRATE_NO_COPY) {
+ rc = folio_mc_copy(dst, src);
+ if (unlikely(rc))
+ return rc;
+ }
rc = __folio_migrate_mapping(mapping, dst, src, expected_count);
if (rc != MIGRATEPAGE_SUCCESS)
--
2.34.1
