linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: clear cold data flag if IO is not counted

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Date:   Wed, 17 Oct 2018 10:50:48 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: clear cold data flag if IO is not
 counted

On 2018/10/17 10:34, Jaegeuk Kim wrote:
> This reverts commit 66110abc4c931f879d70e83e1281f891699364bf.
> 
> If we clear the cold data flag out of the writeback flow, we can miscount
> -1 by end_io.
> 
> Balancing F2FS Async:
>  - IO (CP:    1, Data:   -1, Flush: (   0    0    1), Discard: (   ...
> 
> GC thread:                              IRQ
> - move_data_page()
>  - set_page_dirty()
>   - clear_cold_data()
>                                         - f2fs_write_end_io()
>                                          - type = WB_DATA_TYPE(page);
>                                            here, we get wrong type
>                                          - dec_page_count(sbi, type);
>  - f2fs_wait_on_page_writeback()
> 
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

Thanks,