[PATCH] erofs: fix compacted_2b if compacted_4b_initial > totalidx

[Chao Yu]

On 2021/9/23 19:49, Gao Xiang wrote:
> On Tue, Sep 14, 2021 at 12:57:48PM +0800, Yue Hu wrote:
>> On Tue, 14 Sep 2021 12:37:14 +0800
>> Gao Xiang <hsiangkao at linux.alibaba.com> wrote:
>>
>>> On Tue, Sep 14, 2021 at 11:59:15AM +0800, Yue Hu wrote:
>>>> From: Yue Hu <huyue2 at yulong.com>
>>>>
>>>> Currently, the whole indexes will only be compacted 4B if
>>>> compacted_4b_initial > totalidx. So, the calculated compacted_2b
>>>> is worthless for that case. It may waste CPU resources.
>>>>
>>>> No need to update compacted_4b_initial as mkfs since it's used to
>>>> fulfill the alignment of the 1st compacted_2b pack and would handle
>>>> the case above.
>>>>
>>>> We also need to clarify compacted_4b_end here. It's used for the
>>>> last lclusters which aren't fitted in the previous compacted_2b
>>>> packs.
>>>>
>>>> Some messages are from Xiang.
>>>>
>>>> Signed-off-by: Yue Hu <huyue2 at yulong.com>
>>>
>>> Looks good to me,
>>> Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>
>>>
>>> (although I think the subject title would be better changed into
>>>   "clear compacted_2b if compacted_4b_initial > totalidx"
>>
>> Yeah, 'clear' is much better for this change.
>>
>> Thanks.
>>
>>>   since 'fix'-likewise words could trigger some AI bot for stable
>>>   kernel backporting..)
>>>
>>> Thanks,
>>> Gao Xiang
>>>
>>>> ---
>>>>   fs/erofs/zmap.c | 3 ++-
>>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
>>>> index 9fb98d8..aeed404 100644
>>>> --- a/fs/erofs/zmap.c
>>>> +++ b/fs/erofs/zmap.c
>>>> @@ -369,7 +369,8 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
>>>>   	if (compacted_4b_initial == 32 / 4)
>>>>   		compacted_4b_initial = 0;
>>>>   
>>>> -	if (vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B)
>>>> +	if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&
>>>> +	    compacted_4b_initial <= totalidx) {
> 
> btw, I've fixed up the build error due to redundant brace '{' when
> applying...

It looks good to me after above fix.

Reviewed-by: Chao Yu <chao at kernel.org>

Thanks,