linux-kernel - Re: [PATCH -next v3 6/7] md: factor out a helper rdev_addable() from remove_and_add

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Message-ID: <CAPhsuW5DytoZDTi1NEv_EDaKoaHNE9Vd3UU_O_-2XzVqq0YNwg@mail.gmail.com>
Date:   Wed, 23 Aug 2023 04:25:33 -0700
From:   Song Liu <song@...nel.org>
To:     Yu Kuai <yukuai1@...weicloud.com>
Cc:     xni@...hat.com, mariusz.tkaczyk@...ux.intel.com,
        linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, yangerkun@...wei.com,
        "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH -next v3 6/7] md: factor out a helper rdev_addable() from remove_and_add_spares()

On Wed, Aug 23, 2023 at 1:37 AM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
[...]
> > diff --git i/drivers/md/md.c w/drivers/md/md.c
> > index 78be7811a89f..8cb855d03e0a 100644
> > --- i/drivers/md/md.c
> > +++ w/drivers/md/md.c
> > @@ -9117,6 +9117,20 @@ void md_do_sync(struct md_thread *thread)
> >   }
> >   EXPORT_SYMBOL_GPL(md_do_sync);
> >
> > +static bool rdev_addable(struct md_rdev *rdev)
> > +{
> > +       if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
> > +           test_bit(Faulty, &rdev->flags))
> > +               return false;
> > +       return true;
> > +}
> > +
> > +static bool rdev_is_readd(struct md_rdev *rdev)
> > +{
> > +       return rdev->saved_raid_disk >= 0 ||
> > +               !test_bit(Bitmap_sync, &rdev->flags);
> This should use '&&' instead of '||' ?
>
> > +}
> > +
> >   static int remove_and_add_spares(struct mddev *mddev,
> >                                   struct md_rdev *this)
> >   {
> > @@ -9176,25 +9190,24 @@ static int remove_and_add_spares(struct mddev *mddev,
> >          rdev_for_each(rdev, mddev) {
> >                  if (this && this != rdev)
> >                          continue;
> > -               if (test_bit(Candidate, &rdev->flags))
> > -                       continue;
> >                  if (rdev->raid_disk >= 0 &&
> >                      !test_bit(In_sync, &rdev->flags) &&
> >                      !test_bit(Journal, &rdev->flags) &&
> >                      !test_bit(Faulty, &rdev->flags))
> >                          spares++;
> > -               if (rdev->raid_disk >= 0)
> > +
> > +               if (!rdev_addable(rdev))
> >                          continue;
> > -               if (test_bit(Faulty, &rdev->flags))
> > +
> > +               if (test_bit(Journal, &rdev->flags))
> > +                       goto hot_add_disk;
> > +
>
> I understand what you mean now, but I must use the exact same judgement
> in the new helper md_spares_need_change() in patch 7, there will be
> redundant code this way.
>
> How about this, rework rdev_addable():

Yeah, this was another option that I was thinking about. Let's go with
this version.

Thanks,
Song

>
>    static bool rdev_addable(struct md_rdev *rdev)
>    {
> +         /* rdev is already used, don't add it again. */
>            if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
>                test_bit(Faulty, &rdev->flags))
>                    return false;
>
> ~         /* Allow to add journal disk. */
> ~         if (test_bit(Journal, &rdev->flags))
> ~_                return true;
>
> ~         /* Allow to add if array is read-write. */
> +         if (md_is_rdwr(rdev->mddev))
> +                 return true;
> +
> +         /*
> +          * For read-only array, only allow to readd a rdev. And if
> bitmap is
> +          * used, don't allow to readd a rdev that is too old.
> +          */
> +         if (rdev->saved_raid_disk >=0 && !test_bit(Bitmap_sync,
> &rdev->flags))
> +                 return true;
> +
> +         return false;
>    }