In order to support poisoned folio copy recover from migrate folio,
let's use folio_mc_copy() and move it in the begin of the function
of __migrate_folio(), which could simply error handling since there
is no turning back if folio_migrate_mapping() return success, the
downside is the folio copied even though folio_migrate_mapping()
return fail, a small optimization is to check whether folio does
not have extra refs before we do more work ahead in __migrate_folio(),
which could help us avoid unnecessary folio copy.
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
mm/migrate.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 107965bbc852..99286394b5e5 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -661,6 +661,14 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
{
int rc;
+ /* Check whether src does not have extra refs before we do more work */
+ if (folio_ref_count(src) != folio_expected_refs(mapping, src))
+ return -EAGAIN;
+
+ rc = folio_mc_copy(dst, src);
+ if (rc)
+ return rc;
+
rc = folio_migrate_mapping(mapping, dst, src, 0);
if (rc != MIGRATEPAGE_SUCCESS)
return rc;
@@ -668,7 +676,7 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
if (src_private)
folio_attach_private(dst, folio_detach_private(src));
- folio_migrate_copy(dst, src);
+ folio_migrate_flags(dst, src);
return MIGRATEPAGE_SUCCESS;
}
--
2.27.0
