Re: [f2fs-dev] [PATCH] f2fs: return error number for quota_write

[Chao Yu]

On 2017/10/18 2:17, Jaegeuk Kim wrote:
> On 10/17, Chao Yu wrote:
>>
>>
>> On 2017/10/17 7:04, Jaegeuk Kim wrote:
>>> On 10/16, Chao Yu wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2017/10/13 7:15, Jaegeuk Kim wrote:
>>>>> This patch returns an error number to quota_write in order for quota to handle
>>>>> it correctly.
>>>>
>>>> We should return error number like __generic_file_write_iter, right? it
>>>> needs to return written bytes if we have written one page or more, otherwise
>>>> return error number feedbacked from write_begin.
>>>>
>>>> So how about reverting 4f31d26b0c17 ("f2fs: return wrong error number on
>>>> f2fs_quota_write")?
>>>
>>> I thought like that, but realized the code change is somewhat different between
>>> them.
>>
>> Hmm... main structure of codes here is copied from other file systems, is there
>> the same problem in *_quota_write of other file systems?
>>
>> BTW, it looks making below judgment condition being useless.
>>
>> 	if (len == towrite)
>> 		return 0;
> 
> We need this to avoid needless inode updates. :P

For err = 0 and len == towrite case, it more likes a bug of quota that passing
0 in @len.

:(, Oh, still didn't get that why there is difference in between reverting and
this fixing. Can you please explain more about this?

Thanks,

> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>> Thanks,
>>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
>>>>> ---
>>>>>  fs/f2fs/super.c | 5 ++++-
>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>>> index 2feecf5e7f4c..840a0876005b 100644
>>>>> --- a/fs/f2fs/super.c
>>>>> +++ b/fs/f2fs/super.c
>>>>> @@ -1397,8 +1397,11 @@ static ssize_t f2fs_quota_write(struct super_block *sb, int type,
>>>>>  
>>>>>  		err = a_ops->write_begin(NULL, mapping, off, tocopy, 0,
>>>>>  							&page, NULL);
>>>>> -		if (unlikely(err))
>>>>> +		if (unlikely(err)) {
>>>>> +			if (len == towrite)
>>>>> +				return err;
>>>>>  			break;
>>>>> +		}
>>>>>  
>>>>>  		kaddr = kmap_atomic(page);
>>>>>  		memcpy(kaddr + offset, data, tocopy);
>>>>>
>>>
>>> ------------------------------------------------------------------------------
>>> Check out the vibrant tech community on one of the world's most
>>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>>
> 
> .
>