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Date: Thu, 12 Feb 2015 07:44:36 +0300
From: "Denis V. Lunev" <den@openvz.org>
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Subject: Re: [Qemu-devel] [PULL 05/42] block/raw-posix: refactor
 handle_aiocb_write_zeroes a bit
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To: Peter Maydell <peter.maydell@linaro.org>, Kevin Wolf <kwolf@redhat.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>

On 12/02/15 05:29, Peter Maydell wrote:
> On 6 February 2015 at 16:40, Kevin Wolf <kwolf@redhat.com> wrote:
>> From: "Denis V. Lunev" <den@openvz.org>
>>
>> move code dealing with a block device to a separate function. This will
>> allow to implement additional processing for ordinary files.
>> +static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb)
>> +{
>> +    BDRVRawState *s = aiocb->bs->opaque;
>> +
>> +    if (aiocb->aio_type & QEMU_AIO_BLKDEV) {
>> +        return handle_aiocb_write_zeroes_block(aiocb);
>> +    }
>> +
>> +#ifdef CONFIG_XFS
>> +    if (s->is_xfs) {
>> +        return xfs_write_zeroes(s, aiocb->aio_offset, aiocb->aio_nbytes);
>> +    }
>> +#endif
>> +
>> +    return -ENOTSUP;
>> +}
> Hi. This patch has introduced a new compiler warning on OSX:
> block/raw-posix.c:947:19: warning: unused variable 's' [-Wunused-variable]
>      BDRVRawState *s = aiocb->bs->opaque;
>                    ^
>
> and indeed on any host which doesn't define any of CONFIG_XFS,
> CONFIG_FALLOCATE, CONFIG_FALLOCATE_PUNCH_HOLE or
> CONFIG_FALLOCATE_ZERO_RANGE.
>
> What's your preferred fix? Surrounding the variable declaration
> with #if defined(CONFIG_XFS) || defined(CONFIG_FALLOCATE)
> would work but I dunno if some less ugly approach is possible.
>
> [I don't yet build OSX with -Werror because we haven't fixed
> some of the deprecation warnings about the audio APIs, but
> I would like to eventually...]
>
> thanks
> -- PMM
we can just add
   (void)s;
immediately after the declaration.

On the other hand, CONFIG_FALLOCATE_PUNCH_HOLE and 
CONFIG_FALLOCATE_ZERO_RANGE
are completely impossible without CONFIG_FALLOCATE thus

#if defined(CONFIG_FALLOCATE) or defined(CONFIG_XFS)
would be enough.

Regards,
     Den