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

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Message-ID: <c04dc1c1-daeb-ce6e-66c6-8d81ddf03ab8@huawei.com>
Date:   Mon, 4 Sep 2017 10:48:43 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Yunlong Song <yunlong.song@...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

On 2017/9/4 9:54, Yunlong Song wrote:
> 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?

Oh, I just nit-pick, :), how about using 'se->ckpt_valid_blocks will never be
smaller than se->valid_blocks' instead?

And could you just revert Yunlei's patch and add above commit log?

Thanks,

> 
> 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)
>>>
>>
>> .
>>
>