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Subject: Re: [RFC PATCH V2 0/9] Introduce attach/clear_page_private to cleanup
 code
To:     Matthew Wilcox <willy@infradead.org>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        hch@infradead.org, david@fromorbit.com
References: <20200430214450.10662-1-guoqing.jiang@cloud.ionos.com>
 <20200501221626.GC29705@bombadil.infradead.org>
From:   Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Message-ID: <889f9f82-64ba-50b3-147b-459303617aeb@cloud.ionos.com>
Date:   Sat, 2 May 2020 00:42:15 +0200
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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