Re: [PATCH 3/3] raid5: introduce MD_BROKEN

[Song Liu <song@kernel.org>]

On Tue, Mar 22, 2022 at 8:24 AM Mariusz Tkaczyk
<mariusz.tkaczyk@linux.intel.com> wrote:
>
> Raid456 module had allowed to achieve failed state. It was fixed by
> fb73b357fb9 ("raid5: block failing device if raid will be failed").
> This fix introduces a bug, now if raid5 fails during IO, it may result
> with a hung task without completion. Faulty flag on the device is
> necessary to process all requests and is checked many times, mainly in
> analyze_stripe().
[...]

> Cc: stable@vger.kernel.org
> Fixes: fb73b357fb9 ("raid5: block failing device if raid will be failed")
> Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
> ---
>  drivers/md/raid5.c | 48 +++++++++++++++++++++++-----------------------
>  1 file changed, 24 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 7c119208a214..4d76e3a89aa5 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -686,17 +686,20 @@ int raid5_calc_degraded(struct r5conf *conf)
>         return degraded;
>  }
>
> -static int has_failed(struct r5conf *conf)
> +static bool has_failed(struct r5conf *conf)
>  {
> -       int degraded;
> +       int degraded = conf->mddev->degraded;
>
> -       if (conf->mddev->reshape_position == MaxSector)
> -               return conf->mddev->degraded > conf->max_degraded;
> +       if (test_bit(MD_BROKEN, &conf->mddev->flags))
> +               return true;
> +
> +       if (conf->mddev->reshape_position != MaxSector)
> +               degraded = raid5_calc_degraded(conf);
>
> -       degraded = raid5_calc_degraded(conf);
>         if (degraded > conf->max_degraded)

nit: we can just do
   return degraded > conf->max_degraded;

[...]