The migration code used to be able to migrate dirty 9p folios by writing
them back using writepage. When the writepage method was removed,
we neglected to add a migrate_folio method, which means that dirty 9p
folios have been unmovable ever since. This reduced our success at
defragmenting memory on machines which use 9p heavily.
Fixes: 80105ed2fd27 (9p: Use netfslib read/write_iter)
Cc: stable@xxxxxxxxxxxxxxx
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: v9fs@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
fs/9p/vfs_addr.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 32619d146cbc..1286d96a29bc 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -164,4 +164,5 @@ const struct address_space_operations v9fs_addr_operations = {
.invalidate_folio = netfs_invalidate_folio,
.direct_IO = noop_direct_IO,
.writepages = netfs_writepages,
+ .migrate_folio = filemap_migrate_folio,
};
--
2.47.2
