linux-kernel - Re: [PATCH v3 2/3] md: don't leave 'MD_RECOVERY_FROZEN' in error path of md_set

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Date:   Fri, 1 Dec 2023 12:53:29 -0800
From:   Song Liu <song@...nel.org>
To:     Yu Kuai <yukuai1@...weicloud.com>
Cc:     xni@...hat.com, yukuai3@...wei.com, linux-raid@...r.kernel.org,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        yangerkun@...wei.com
Subject: Re: [PATCH v3 2/3] md: don't leave 'MD_RECOVERY_FROZEN' in error path
 of md_set_readonly()

On Tue, Nov 28, 2023 at 8:32 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> If md_set_readonly() failed, the array could still be read-write, however
> 'MD_RECOVERY_FROZEN' could still be set, which leave the array in an
> abnormal state that sync or recovery can't continue anymore.
> Hence make sure the flag is cleared after md_set_readonly() returns.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> Acked-by: Xiao Ni <xni@...hat.com>

Since we are shipping this via the md-fixes branch, we need a Fixes tag.

> ---
>  drivers/md/md.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 5640a948086b..2d8e45a1af23 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -6355,6 +6355,9 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
>         int err = 0;
>         int did_freeze = 0;
>
> +       if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
> +               return -EBUSY;
> +
>         if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
>                 did_freeze = 1;
>                 set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> @@ -6369,8 +6372,6 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
>          */
>         md_wakeup_thread_directly(mddev->sync_thread);
>
> -       if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
> -               return -EBUSY;
>         mddev_unlock(mddev);
>         wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING,
>                                           &mddev->recovery));
> @@ -6383,29 +6384,30 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
>             mddev->sync_thread ||
>             test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
>                 pr_warn("md: %s still in use.\n",mdname(mddev));
> -               if (did_freeze) {
> -                       clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> -                       set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> -                       md_wakeup_thread(mddev->thread);
> -               }

This change (move did_freeze, etc.) is not explained in the commit log.
Is it just refactor?

Thanks,
Song


>                 err = -EBUSY;
>                 goto out;
>         }
> +
>         if (mddev->pers) {
>                 __md_stop_writes(mddev);
>
> -               err  = -ENXIO;
> -               if (mddev->ro == MD_RDONLY)
> +               if (mddev->ro == MD_RDONLY) {
> +                       err  = -ENXIO;
>                         goto out;
> +               }
> +
>                 mddev->ro = MD_RDONLY;
>                 set_disk_ro(mddev->gendisk, 1);
> +       }
> +
> +out:
> +       if ((mddev->pers && !err) || did_freeze) {
>                 clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
>                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
>                 md_wakeup_thread(mddev->thread);
>                 sysfs_notify_dirent_safe(mddev->sysfs_state);
> -               err = 0;
>         }
> -out:
> +
>         mutex_unlock(&mddev->open_mutex);
>         return err;
>  }
> --
> 2.39.2
>