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Subject: RE:(2) [PATCH v1] f2fs: avoid victim selection from previous victim
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Reply-To: yonggil.song@samsung.com
Sender: Yonggil Song <yonggil.song@samsung.com>
From:   Yonggil Song <yonggil.song@samsung.com>
To:     Chao Yu <chao@kernel.org>,
        "jaegeuk@kernel.org" <jaegeuk@kernel.org>,
        "linux-f2fs-devel@lists.sourceforge.net" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Message-ID: <20221122085649epcms2p5b72ef048e5ac93c02859611fd2233c3a@epcms2p5>
Date:   Tue, 22 Nov 2022 17:56:49 +0900
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Hi Chao,

Thanks for your review.
I'll fix this and resend a mail.

Thanks

>Hi Yonggil,
>
>I guess your email client forces converting tab and space characters of
>patch, please check that.
>
>On 2022/11/22 10:36, Yonggil Song wrote:
>> When f2fs chooses GC victim in large section & LFS mode,
>> next_victim_seg[gc_type] is referenced first. After segment is freed,
>> next_victim_seg[gc_type] has the next segment number.
>> However, next_victim_seg[gc_type] still has the last segment number
>> even after the last segment of section is freed. In this case, when f2fs
>> chooses a victim for the next GC round, the last segment of previous victim
>> section is chosen as a victim.
>> 
>> Initialize next_victim_seg[gc_type] to NULL_SEGNO for the last segment in
>> large section.
>> 
>> Fixes: e3080b0120a1 ("f2fs: support subsectional garbage collection")
>
>Good catch, I'm fine with this fix.
>
>Thanks,
>
>> Signed-off-by: Yonggil Song <yonggil.song@samsung.com>
>> ---
>>   fs/f2fs/gc.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 4546e01b2ee0..10677d53ef0e 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -1744,8 +1744,9 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>                                   get_valid_blocks(sbi, segno, false) == 0)
>>                           seg_freed++;
>>   
>> -                if (__is_large_section(sbi) && segno + 1 < end_segno)
>> -                        sbi->next_victim_seg[gc_type] = segno + 1;
>> +                if (__is_large_section(sbi))
>> +                        sbi->next_victim_seg[gc_type] =
>> +                                (segno + 1 < end_segno) ? segno + 1 : NULL_SEGNO;
>>   skip:
>>                   f2fs_put_page(sum_page, 0);
>>           }
>> -- 
>> 2.34.1