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Re: [PATCH] f2fs: discard small invalid blocks in current active segments

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How? Can the invalid blocks of file A be discarded, if file B is alive 
all the time and fggc_threshold is 507 ?

On 2017/8/28 17:59, Chao Yu wrote:
> On 2017/8/26 20:49, Yunlong Song wrote:
>> 1. write file A with 5 blocks to current empty active segment
>> 2. remove file A
>> 3. write checkpoint
>> 4. write file B with 507 blocks to the same active segment
>>
>> If file B is alive all the time, the blocks used by file A will never be
>> discarded. So current active segment should also be treated as a candidate
>> for small discards.
> I don't think that would be a big issue, since there will not be any freezing
> log headers, once log header moves, later invalid blocks could be discarded.
>
> Thanks,
>
>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
>> ---
>>   fs/f2fs/segment.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 8375257..a2e7c8f 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,
>>   		return false;
>>   
>>   	if (!force) {
>> -		if (!test_opt(sbi, DISCARD) || !se->valid_blocks ||
>> +		if (!test_opt(sbi, DISCARD) ||
>> +			(!se->valid_blocks &&
>> +			!IS_CURSEG(sbi, cpc->trim_start)) ||
>>   			SM_I(sbi)->dcc_info->nr_discards >=
>>   				SM_I(sbi)->dcc_info->max_discards)
>>   			return false;
>>
>
> .
>

-- 
Thanks,
Yunlong Song

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Thread

[PATCH] f2fs: discard small invalid blocks in current active segments Yunlong Song <yunlong.song@huawei.com> - 2017-08-26 15:00 +0200
  Re: [PATCH] f2fs: discard small invalid blocks in current active  segments Chao Yu <yuchao0@huawei.com> - 2017-08-28 12:10 +0200
    Re: [PATCH] f2fs: discard small invalid blocks in current active  segments Yunlong Song <yunlong.song@huawei.com> - 2017-08-28 15:30 +0200
      Re: [PATCH] f2fs: discard small invalid blocks in current active  segments Chao Yu <yuchao0@huawei.com> - 2017-08-29 12:10 +0200

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