Re: [RFC PATCH V2 0/9] Introduce attach/clear_page_private to cleanup code

[Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>]

On 5/2/20 12:16 AM, Matthew Wilcox wrote:
> On Thu, Apr 30, 2020 at 11:44:41PM +0200, Guoqing Jiang wrote:
> >    include/linux/pagemap.h: introduce attach/clear_page_private
> >    md: remove __clear_page_buffers and use attach/clear_page_private
> >    btrfs: use attach/clear_page_private
> >    fs/buffer.c: use attach/clear_page_private
> >    f2fs: use attach/clear_page_private
> >    iomap: use attach/clear_page_private
> >    ntfs: replace attach_page_buffers with attach_page_private
> >    orangefs: use attach/clear_page_private
> >    buffer_head.h: remove attach_page_buffers
> I think mm/migrate.c could also use this:
>
>          ClearPagePrivate(page);
>          set_page_private(newpage, page_private(page));
>          set_page_private(page, 0);
>          put_page(page);
>          get_page(newpage);

Thanks for checking!  Assume the below change is appropriate.

diff --git a/mm/migrate.c b/mm/migrate.c
index 7160c1556f79..f214adfb3fa4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -797,10 +797,7 @@ static int __buffer_migrate_page(struct 
address_space *mapping,
        if (rc != MIGRATEPAGE_SUCCESS)
                goto unlock_buffers;

-       ClearPagePrivate(page);
-       set_page_private(newpage, page_private(page));
-       set_page_private(page, 0);
-       put_page(page);
+       set_page_private(newpage, detach_page_private(page));
        get_page(newpage);

        bh = head;


Cheers,
Guoqing