Re: [f2fs-dev] [PATCH v4] f2fs: add f2fs_gc exception handle in f2fs_ioc_gc_range

[Chao Yu <yuchao0@huawei.com>]

On 2020/6/28 16:06, yuchangchun (C) wrote:
> 在 2020/6/28 14:39, Qilong Zhang 写道:
>> When f2fs_ioc_gc_range performs multiple segments gc ops, the return
>> value of f2fs_ioc_gc_range is determined by the last segment gc ops.
>> If its ops failed, the f2fs_ioc_gc_range will be considered to be failed
>> despite some of previous segments gc ops succeeded. Therefore, so we
>> fix: Redefine the return value of getting victim ops and add exception
>> handle for f2fs_gc. In particular, 1).if target has no valid block, it
>> will go on. 2).if target sectoion has valid block(s), but it is current
>> section, we will reminder the caller.
>>
>> Signed-off-by: Qilong Zhang <zhangqilong3@huawei.com>
>> Reviewed-by: Chao Yu <yuchao0@huawei.com>
>> ---
>>   fs/f2fs/file.c    |  5 +++++
>>   fs/f2fs/gc.c      | 19 +++++++++++++------
>>   fs/f2fs/segment.c |  4 ++--
>>   3 files changed, 20 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 3268f8dd59bb..fe006477a4e4 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -2527,6 +2527,11 @@ static int f2fs_ioc_gc_range(struct file *filp, unsigned long arg)
>>   	}
>>   
>>   	ret = f2fs_gc(sbi, range.sync, true, GET_SEGNO(sbi, range.start));
>> +	if (ret) {
>> +		if (ret == -EBUSY)
>> +			ret = -EAGAIN;
>> +		goto out;
>> +	}
>>   	range.start += BLKS_PER_SEC(sbi);
>>   	if (range.start <= end)
>>   		goto do_more;
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index 5b95d5a146eb..71cb4a02aeee 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -321,6 +321,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>   	unsigned int secno, last_victim;
>>   	unsigned int last_segment;
>>   	unsigned int nsearched = 0;
>> +	int ret;
>>   
>>   	mutex_lock(&dirty_i->seglist_lock);
>>   	last_segment = MAIN_SECS(sbi) * sbi->segs_per_sec;
>> @@ -332,12 +333,18 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>   	p.min_cost = get_max_cost(sbi, &p);
>>   
>>   	if (*result != NULL_SEGNO) {
>> -		if (get_valid_blocks(sbi, *result, false) &&
>> -			!sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result)))
>> +		ret = 0;
>> +		if (!get_valid_blocks(sbi, *result, false))
>> +			goto out;
> Should it return specific errno to stop GC if this victim segment has no 
> valid blocks  in accordance with original code.

Agreed, could be:

if (!get_valid_blocks(sbi, *result, false)) {
	ret = -ENODATA;
	goto out;
}

Thanks,

> 
> Thanks,
> 
>> +
>> +		if (sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result)))
>> +			ret = -EBUSY;
>> +		else
>>   			p.min_segno = *result;
>>   		goto out;
>>   	}
>>   
>> +	ret = -ENODATA;
>>   	if (p.max_search == 0)
>>   		goto out;
>>   
>> @@ -440,6 +447,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>   			else
>>   				set_bit(secno, dirty_i->victim_secmap);
>>   		}
>> +		ret = 0;
>>   
>>   	}
>>   out:
>> @@ -449,7 +457,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>   				prefree_segments(sbi), free_segments(sbi));
>>   	mutex_unlock(&dirty_i->seglist_lock);
>>   
>> -	return (p.min_segno == NULL_SEGNO) ? 0 : 1;
>> +	return ret;
>>   }
>>   
>>   static const struct victim_selection default_v_ops = {
>> @@ -1333,10 +1341,9 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>>   		ret = -EINVAL;
>>   		goto stop;
>>   	}
>> -	if (!__get_victim(sbi, &segno, gc_type)) {
>> -		ret = -ENODATA;
>> +	ret = __get_victim(sbi, &segno, gc_type);
>> +	if (ret)
>>   		goto stop;
>> -	}
>>   
>>   	seg_freed = do_garbage_collect(sbi, segno, &gc_list, gc_type);
>>   	if (gc_type == FG_GC && seg_freed == sbi->segs_per_sec)
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 196f31503511..b9fd93761b0a 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2605,7 +2605,7 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
>>   	bool reversed = false;
>>   
>>   	/* f2fs_need_SSR() already forces to do this */
>> -	if (v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
>> +	if (!v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
>>   		curseg->next_segno = segno;
>>   		return 1;
>>   	}
>> @@ -2632,7 +2632,7 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
>>   	for (; cnt-- > 0; reversed ? i-- : i++) {
>>   		if (i == type)
>>   			continue;
>> -		if (v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
>> +		if (!v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
>>   			curseg->next_segno = segno;
>>   			return 1;
>>   		}
> 
> 
> 
> .
> 


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