Re: [PATCH 1/9] fstests: btrfs: _scratch_mkfs_sized fix min size without mixed option

[Anand Jain <anand.jain@oracle.com>]

On 09/24/2018 08:02 PM, Qu Wenruo wrote:
> 
> 
> On 2018/9/24 下午7:53, Anand Jain wrote:
>>
>>
>> On 09/24/2018 06:58 PM, Qu Wenruo wrote:
>>>
>>>
>>> On 2018/9/24 下午6:16, Anand Jain wrote:
>>>> As of now _scratch_mkfs_sized check if the requested size is below 1G
>>>> and forces the --mixed option for the mkfs.btrfs. Well the correct size
>>>> at which we need to force the mixed option is 114294784bytes. Fix that.
>>>
>>> How this size is get from?
>>> If it's from btrfs_min_dev_size(), I strongly recommend to add reference
>>> here, and don't use the ugly intermediate number.
>>>
>>>
>>> BTW, this number is related to mkfs profile.
>>> If you really want to use some maximum number, please follow the max
>>> possible value in btrfs_min_dev_size(), which should be 229M other than
>>> 106M.
>>
>>   Thanks for the comments. I completely missed out the point of other
>>   group profile requiring more than ~115 bytes. Will fix.
> 
> I'd go a rounded number, like 256M.
> 
> Non of the number from btrfs_min_dev_size() is really easy to remember
> nor makes sense out of btrfs realm.
> 
> And this also leaves a little more headroom for later modification
> (although I hope such modification never happen)

  I agree. Actually I was thinking it should be like that when I was 
writing this patch, then my logical mind didn't provide any strong 
reason to back that up. As ideas match, Will fix it at 256M.

Thanks, Anand


> Thanks,
> Qu
> 
>>   Yep the ref for the size is btrfs_min_dev_size().
>>
>> -Anand
>>
>>
>>> Thanks,
>>> Qu
>>>
>>>>
>>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>>> ---
>>>>    common/rc | 4 +++-
>>>>    1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/common/rc b/common/rc
>>>> index d5bb1feee2c3..bcdbf03e1bf0 100644
>>>> --- a/common/rc
>>>> +++ b/common/rc
>>>> @@ -969,7 +969,9 @@ _scratch_mkfs_sized()
>>>>        ;;
>>>>        btrfs)
>>>>        local mixed_opt=
>>>> -    (( fssize <= 1024 * 1024 * 1024 )) && mixed_opt='--mixed'
>>>> +    # minimum size that's needed without the mixed option.
>>>> +    # Non mixed mode is also the default option.
>>>> +    (( fssize < 114294784 )) && mixed_opt='--mixed'
>>>>        $MKFS_BTRFS_PROG $MKFS_OPTIONS $mixed_opt -b $fssize $SCRATCH_DEV
>>>>        ;;
>>>>        jfs)
>>>>
>>>
>