Re: [PATCH] btrfs: add test case to verify that btrfs won't waste IO/CPU to defrag compressed extents already at their max size

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2022/1/27 23:38, Ritesh Harjani wrote:
> On 22/01/27 01:53PM, Qu Wenruo wrote:
>> There is a long existing bug in btrfs defrag code that it will always
>> try to defrag compressed extents, even they are already at max capacity.
>>
>> This will not reduce the number of extents, but only waste IO/CPU.
>>
>> The kernel fix is titled:
>>
>>    btrfs: defrag: don't defrag extents which is already at its max capacity
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> ---
>>   tests/btrfs/257     | 79 +++++++++++++++++++++++++++++++++++++++++++++
>>   tests/btrfs/257.out |  2 ++
>>   2 files changed, 81 insertions(+)
>>   create mode 100755 tests/btrfs/257
>>   create mode 100644 tests/btrfs/257.out
>>
>> diff --git a/tests/btrfs/257 b/tests/btrfs/257
>> new file mode 100755
>> index 00000000..326687dc
>> --- /dev/null
>> +++ b/tests/btrfs/257
>> @@ -0,0 +1,79 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (C) 2022 SUSE Linux Products GmbH. All Rights Reserved.
>> +#
>> +# FS QA Test 257
>> +#
>> +# Make sure btrfs defrag ioctl won't defrag compressed extents which are already
>> +# at their max capacity.
>
> Haven't really looked into this fstest. But it is a good practice to add the
> commit id and the title here for others to easily refer kernel commit.

Isn't that already in the commit message?

Thanks,
Qu
>
> -ritesh
>