linux-kernel - Re: [PATCH] f2fs: clear get_ssr

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Message-ID: <e78cb8f1-99ee-672b-ffc0-1a5fdf9df908@huawei.com>
Date:   Mon, 4 Sep 2017 09:54:07 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     Chao Yu <yuchao0@...wei.com>, <jaegeuk@...nel.org>,
        <chao@...nel.org>, <yunlong.song@...oud.com>
CC:     <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: clear get_ssr_cost

The update_sit_entry provides this:
...
1658     if (!f2fs_test_bit(offset, se->ckpt_valid_map))
1659         se->ckpt_valid_blocks += del;
...
As a result, the ckpt_valid_blocks is always larger than valid_blocks. 
If not correct, can you provide
the case valid_blocks larger than ckpt_valid_blocks?

On 2017/9/4 9:17, Chao Yu wrote:
> On 2017/9/1 20:14, Yunlong Song wrote:
>> se->ckpt_valid_blocks is always larger than se->valid_blocks, so
>> get_ssr_cost can be cleared.
> I think this is not correct.
>
> Thanks,
>
>> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
>> ---
>>   fs/f2fs/gc.c | 11 +----------
>>   1 file changed, 1 insertion(+), 10 deletions(-)
>>
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index cd147e7..b226760 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -277,20 +277,11 @@ static unsigned int get_greedy_cost(struct f2fs_sb_info *sbi,
>>   				valid_blocks * 2 : valid_blocks;
>>   }
>>   
>> -static unsigned int get_ssr_cost(struct f2fs_sb_info *sbi,
>> -						unsigned int segno)
>> -{
>> -	struct seg_entry *se = get_seg_entry(sbi, segno);
>> -
>> -	return se->ckpt_valid_blocks > se->valid_blocks ?
>> -				se->ckpt_valid_blocks : se->valid_blocks;
>> -}
>> -
>>   static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
>>   			unsigned int segno, struct victim_sel_policy *p)
>>   {
>>   	if (p->alloc_mode == SSR)
>> -		return get_ssr_cost(sbi, segno);
>> +		return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
>>   
>>   	/* alloc_mode == LFS */
>>   	if (p->gc_mode == GC_GREEDY)
>>
>
> .
>

-- 
Thanks,
Yunlong Song