Re: [PATCH] btrfs/124: add balance --full-balance option

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

On 12/05/2017 04:40 PM, Eryu Guan wrote:
> On Tue, Dec 05, 2017 at 04:30:33PM +0800, Qu Wenruo wrote:
>>
>>
>> On 2017年12月05日 16:26, Anand Jain wrote:
>>> btrfs balance needs --full-balance option since 4.6, so check the
>>> version and then use it.
>>>
>>> As this may be useful for other btrfs tests as well, so this patch
>>> adds _btrfs_full_balance_option() to the common/btrfs file.
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> ---
>>>   common/btrfs    | 13 +++++++++++++
>>>   tests/btrfs/124 |  3 ++-
>>>   2 files changed, 15 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/common/btrfs b/common/btrfs
>>> index c09206c6f292..8ca6486b26dc 100644
>>> --- a/common/btrfs
>>> +++ b/common/btrfs
>>> @@ -356,3 +356,16 @@ _btrfs_compression_algos()
>>>   		echo "${feature#/sys/fs/btrfs/features/compress_}"
>>>   	done
>>>   }
>>> +
>>> +#btrfs-progs adds required --full-balance option since v4.6 so check for
>>> +#that and then return the required option.
>>> +_btrfs_full_balance_option()
>>> +{
>>> +	ver=$($BTRFS_UTIL_PROG --version|awk '{print $2}'|cut -d"-" -f1 | cut -d"v" -f2)
>>
>> I'm never a fan of version check.
>> Backporting or modified package version can easily screw this up.
> 
> Agreed, avoid version checking if possible.
> 
>>
>> Why not directly checking the help message of "btrfs balance start"?
>>
>> Thanks,
>> Qu
>>
>>> +	tup1=$(echo $ver| cut -d"." -f1)
>>> +	tup2=$(echo $ver| cut -d"." -f2)
> 
> And please declare local variables as 'local'.

  ok.

>>> +
>>> +	RET=""
>>> +	(("$tup1" > "4")) && RET="--full-balance"
>>> +	(("$tup1" == "4")) && (("tup2" >= "6")) && RET="--full-balance"
>>> +}
>>> diff --git a/tests/btrfs/124 b/tests/btrfs/124
>>> index a6486270a972..ec1d24b5ef42 100755
>>> --- a/tests/btrfs/124
>>> +++ b/tests/btrfs/124
>>> @@ -129,7 +129,8 @@ _run_btrfs_util_prog device scan
>>>   _scratch_mount >> $seqres.full 2>&1
>>>   _run_btrfs_util_prog filesystem show
>>>   echo >> $seqres.full
>>> -_run_btrfs_util_prog balance start ${SCRATCH_MNT}
>>> +_btrfs_full_balance_option
>>> +_run_btrfs_util_prog balance start $RET ${SCRATCH_MNT}
> 
> This usage depends on the implicit global variable RET, which seems a
> bit hard to follow. How about let the new helper return the expected
> option string, and use that string in test, either assign it to a local
> var or use it in command line directly.
> 
> Think about it more, perhaps we can introduce a new helper, e.g.
> _run_btrfs_balance, and hide all these details, just call balance with
> --full-balance when possible?

  Ah. That's much better. Will do.

Thanks, Anand


> Thanks,
> Eryu
> 
>>>   
>>>   checkpoint2=`md5sum $SCRATCH_MNT/tf2`
>>>   echo $checkpoint2 >> $seqres.full 2>&1
>>>
>>
> 
> 
> 
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