Re: [PATCH v2] generic/520: Remove sync in clean_dir

[Yang Xu <xuyang2018.jy@cn.fujitsu.com>]

on 2020/01/16 23:35, Darrick J. Wong wrote:
> On Mon, Dec 23, 2019 at 06:21:39PM +0800, Yang Xu wrote:
>> When I test this case on xfs, it may fail as below:
>> --------------------------------------------
>>   === link SCRATCH_MNT/A/foo SCRATCH_MNT/bar  with fsync SCRATCH_MNT/A ===
>> +umount: /mnt/xfstests/scratch: target is busy.
>> +        (In some cases useful info about processes that use
>> +         the device is found by lsof(8) or fuser(1))
>> ---------------------------------------------
>>
>> It fails because somethings is still using the fs when we call sync and then
>> try to unmount it. We can simply remove sync as the unmount is supposed to
>> persist the file/directory removals.
> 
> /me continues to wonder why the target is busy in this case, but as the
> sync truly isn't necessary:
I don't konw(I use fuser or lsof to debug, but no useful info).  I guess 
call sync frequently in a case will cause this. sync doesn't ensure 
cached push into disk, also sync doesn't have fixed order(it may push 
other into disk, then push SCRATCH_DEV cached write into disk, between 
them, umount will report target busy, this happens randomly).

Also, my colleague has a smiliar bug for generic/442 when we remove dm 
device. If you can review it, I will be very grateful.
https://patchwork.kernel.org/patch/11160197

Best Regard
Yang Xu
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D
> 
>> Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
>> ---
>>   tests/generic/520 | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/tests/generic/520 b/tests/generic/520
>> index 167d7077..d4457370 100755
>> --- a/tests/generic/520
>> +++ b/tests/generic/520
>> @@ -58,7 +58,6 @@ clean_dir()
>>   {
>>   	_mount_flakey
>>   	rm -rf $(find $SCRATCH_MNT/* | grep -v "lost+found")
>> -	sync
>>   	_unmount_flakey
>>   }
>>   
>> -- 
>> 2.18.0
>>
>>
>>
> 
>