Re: [PATCH 2/2] f2fs: Enhance the subsequent logic of valid_thresh_ratio to prevent unnecessary background GC

[Chao Yu <chao@kernel.org>]

On 9/17/25 15:08, Liao Yuanhong wrote:
> 
> On 9/15/2025 4:36 PM, Chao Yu wrote:
>> On 9/9/25 21:44, Liao Yuanhong wrote:
>>> When the proportion of dirty segments within a section exceeds the
>>> valid_thresh_ratio, the gc_cost of that section is set to UINT_MAX,
>>> indicating that these sections should not be released. However, if all
>>> section costs within the scanning range of get_victim() are UINT_MAX,
>>> background GC will still occur. Add a condition to prevent this situation.
>> For this case, f2fs_get_victim() will return 0, and f2fs_gc() will use unchanged
>> segno for GC?
>>
>> Thanks,
> 
> You're right, segno won't update in this scenario, and this patch feature is redundant.

Oh, I meant, if f2fs_get_victim() fails to select a valid victim due to the reason you
described, f2fs_get_victim() will return 0, and f2fs_gc() will migrate segment #NULL_SEGNO?
Or am I missing something?

Thanks,

> 
> 
> Thanks,
> 
> Liao
> 
>>> Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
>>> ---
>>>   fs/f2fs/gc.c | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>>
>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>> index 4a8c08f970e3..ffc3188416f4 100644
>>> --- a/fs/f2fs/gc.c
>>> +++ b/fs/f2fs/gc.c
>>> @@ -936,6 +936,11 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
>>>           }
>>>       }
>>>   +    if (f2fs_sb_has_blkzoned(sbi) && p.min_cost == UINT_MAX) {
>>> +        ret = -ENODATA;
>>> +        goto out;
>>> +    }
>>> +
>>>       /* get victim for GC_AT/AT_SSR */
>>>       if (is_atgc) {
>>>           lookup_victim_by_age(sbi, &p);