IOMAP uses PG_private a little different with buffer_head based
filesystem.
It uses it as marker and when set, the page counter is not incremented,
migrate_page_move_mapping() assumes that PG_private indicates a counter
of +1.
so, we have to pass a extra count of -1 to migrate_page_move_mapping()
if the flag is set.
Signed-off-by: zhangjun <openzhangj@xxxxxxxxx>
---
fs/iomap.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/iomap.c b/fs/iomap.c
index 64ce240..352e58a 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -544,8 +544,17 @@ iomap_migrate_page(struct address_space *mapping, struct page *newpage,
struct page *page, enum migrate_mode mode)
{
int ret;
+ int extra_count = 0;
- ret = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
+ /*
+ * IOMAP uses PG_private as marker and does not raise the page counter.
+ * migrate_page_move_mapping() expects a incremented counter if PG_private
+ * is set. Therefore pass -1 as extra_count for this case.
+ */
+ if (page_has_private(page))
+ extra_count = -1;
+ ret = migrate_page_move_mapping(mapping, newpage, page,
+ NULL, mode, extra_count);
if (ret != MIGRATEPAGE_SUCCESS)
return ret;
--
2.7.4
