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References: <20230628015752.102267-1-linan666@huaweicloud.com> <20230628015752.102267-3-linan666@huaweicloud.com>
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From:   Song Liu <song@kernel.org>
Date:   Fri, 30 Jun 2023 16:53:57 -0700
Message-ID: <CAPhsuW7ySGEQtSHg0jxvRRDQWumF7DsVF8fro6MYCc_bY6Ssew@mail.gmail.com>
Subject: Re: [PATCH 2/3] md/raid10: factor out get_rdev_repl_from_mirror()
To:     linan666@huaweicloud.com
Cc:     guoqing.jiang@cloud.ionos.com, colyli@suse.de, xni@redhat.com,
        linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        linan122@huawei.com, yukuai3@huawei.com, yi.zhang@huawei.com,
        houtao1@huawei.com, yangerkun@huawei.com
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On Tue, Jun 27, 2023 at 6:58=E2=80=AFPM <linan666@huaweicloud.com> wrote:
>
[...]

>
> +static void get_rdev_repl_from_mirror(struct raid10_info *mirror,
> +                                struct md_rdev **prdev,
> +                                struct md_rdev **prrdev)
> +{
> +       struct md_rdev *rdev, *rrdev;
> +
> +       rrdev =3D rcu_dereference(mirror->replacement);
> +       /*
> +        * Read replacement first to prevent reading both rdev and
> +        * replacement as NULL during replacement replace rdev.
> +        */
> +       smp_mb();
> +       rdev =3D rcu_dereference(mirror->rdev);
> +       if (rdev =3D=3D rrdev)
> +               rrdev =3D NULL;
> +
> +       *prrdev =3D rrdev;
> +       *prdev =3D rdev;

I don't think the reduction in duplicated code justifies two output argumen=
ts.

How about

static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirro=
r,
                               struct md_rdev **prrdev)
{
    ...
    *prrdev =3D xxx;
    return rdev;
}

So we only have one argument for output.

Also, "from_mirror" in the function name doesn't really add more value.

Thanks,
Song