linux-kernel - Re: [PATCH] f2fs: Fix type of single bit bitfield in f2fs_io

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Date:   Thu, 2 Feb 2023 15:11:18 +0800
From:   Chao Yu <chao@...nel.org>
To:     Nathan Chancellor <nathan@...nel.org>
Cc:     jaegeuk@...nel.org, ndesaulniers@...gle.com, trix@...hat.com,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        patches@...ts.linux.dev, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] f2fs: Fix type of single bit bitfield in f2fs_io_info

On 2023/2/2 14:15, Nathan Chancellor wrote:
> On Thu, Feb 02, 2023 at 02:13:18PM +0800, Chao Yu wrote:
>> On 2023/2/2 0:40, Nathan Chancellor wrote:
>>> Clang warns:
>>>
>>>     ../fs/f2fs/data.c:995:17: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>             fio->submitted = 1;
>>>                            ^ ~
>>>     ../fs/f2fs/data.c:1011:15: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>                             fio->retry = 1;
>>>                                        ^ ~
>>>
>>>     ../fs/f2fs/segment.c:3320:16: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion]
>>>                     fio->in_list = 1;
>>>                                  ^ ~
>>>
>>> There is not a bug here because the value of these fields is never
>>> explicitly compared against (just whether it is zero or non-zero) but
>>> it is easy to silence the warning by using an unsigned type to allow
>>> an assignment of 0 or 1 without implicit conversion.
>>
>> Nathan, thanks a lot for catching this, do you mind letting I merge this fix
>> into original patch? as the original patch has not been upstreamed yet.
> 
> No worries, do whatever you need to! I just care that the problem gets
> resolved one way or another :)

Thank you! Updated a v3 patch. :)

Thanks,

> 
> Cheers,
> Nathan