linux-kernel - Re: [PATCH -next v3 4/7] md: factor out a helper rdev_removeable() from remove_and_add

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Message-ID: <CALTww2-mH7SW3Dz0DOd+NyBpZAZzB8r50UCBOkMipNtV4VxWTw@mail.gmail.com>
Date:   Tue, 22 Aug 2023 18:19:16 +0800
From:   Xiao Ni <xni@...hat.com>
To:     Yu Kuai <yukuai1@...weicloud.com>
Cc:     song@...nel.org, mariusz.tkaczyk@...ux.intel.com,
        linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH -next v3 4/7] md: factor out a helper rdev_removeable()
 from remove_and_add_spares()

On Sun, Aug 20, 2023 at 5:13 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> There are no functional changes, just to make the code simpler and
> prepare to delay remove_and_add_spares() to md_start_sync().
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>  drivers/md/md.c | 33 +++++++++++++++++++--------------
>  1 file changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 561cac13ff96..ceace5ffadd6 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -9153,6 +9153,22 @@ void md_do_sync(struct md_thread *thread)
>  }
>  EXPORT_SYMBOL_GPL(md_do_sync);
>
> +static bool rdev_removeable(struct md_rdev *rdev)
> +{
> +       if (rdev->raid_disk < 0 || test_bit(Blocked, &rdev->flags) ||
> +           atomic_read(&rdev->nr_pending))
> +               return false;
> +
> +       if (test_bit(RemoveSynchronized, &rdev->flags))
> +               return true;
> +
> +       if (test_bit(In_sync, &rdev->flags) ||
> +           test_bit(Journal, &rdev->flags))
> +               return false;
> +
> +       return true;
> +}
> +
>  static int remove_and_add_spares(struct mddev *mddev,
>                                  struct md_rdev *this)
>  {
> @@ -9166,11 +9182,7 @@ static int remove_and_add_spares(struct mddev *mddev,
>                 return 0;
>
>         rdev_for_each(rdev, mddev) {
> -               if ((this == NULL || rdev == this) &&
> -                   rdev->raid_disk >= 0 &&
> -                   !test_bit(Blocked, &rdev->flags) &&
> -                   test_bit(Faulty, &rdev->flags) &&
> -                   atomic_read(&rdev->nr_pending)==0) {
> +               if ((this == NULL || rdev == this) && rdev_removeable(rdev)) {

There is a small change with the original method. Before this patch,
it checks the Faulty flag when setting RemoveSynchronized and it
checks RemoveSynchronized and "!In_sync && !Journal". I'm not sure if
it's right or not.

>                         /* Faulty non-Blocked devices with nr_pending == 0
>                          * never get nr_pending incremented,
>                          * never get Faulty cleared, and never get Blocked set.
> @@ -9185,19 +9197,12 @@ static int remove_and_add_spares(struct mddev *mddev,
>                 synchronize_rcu();
>         rdev_for_each(rdev, mddev) {
>                 if ((this == NULL || rdev == this) &&
> -                   rdev->raid_disk >= 0 &&
> -                   !test_bit(Blocked, &rdev->flags) &&
> -                   ((test_bit(RemoveSynchronized, &rdev->flags) ||
> -                    (!test_bit(In_sync, &rdev->flags) &&
> -                     !test_bit(Journal, &rdev->flags))) &&
> -                   atomic_read(&rdev->nr_pending)==0)) {
> -                       if (mddev->pers->hot_remove_disk(
> -                                   mddev, rdev) == 0) {
> +                   rdev_removeable(rdev) &&
> +                   mddev->pers->hot_remove_disk(mddev, rdev) == 0) {
>                                 sysfs_unlink_rdev(mddev, rdev);
>                                 rdev->saved_raid_disk = rdev->raid_disk;
>                                 rdev->raid_disk = -1;
>                                 removed++;
> -                       }
>                 }
>                 if (remove_some && test_bit(RemoveSynchronized, &rdev->flags))
>                         clear_bit(RemoveSynchronized, &rdev->flags);
> --
> 2.39.2
>