Re: [PATCH v2] md/raid0: Ignore RAID0 layout if the second zone has only one device

[Song Liu <song@kernel.org>]

On Tue, Apr 12, 2022 at 11:54 PM Pascal Hambourg <pascal@plouf.fr.eu.org> wrote:
>
> The RAID0 layout is irrelevant if all members have the same size so the
> array has only one zone. It is *also* irrelevant if the array has two
> zones and the second zone has only one device, for example if the array
> has two members of different sizes.
>
> So in that case it makes sense to allow assembly even when the layout is
> undefined, like what is done when the array has only one zone.
>
> Reviewed-By: NeilBrown <neilb@suse.de>
> Signed-off-by: Pascal Hambourg <pascal@plouf.fr.eu.org>

Thanks for the patch and thanks Neil for the review.

Applied to md-next with two minor changes:

s/ENOTSUPP/EOPNOTSUPP/
s/Reviewed-By/Review-by/

Thanks,
Song

> ---
>
> Changes since v1:
> - add missing Signed-off-by
> - add missing subsystem maintainer in recipients
>
> ---
>   drivers/md/raid0.c | 31 ++++++++++++++++---------------
>   1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index b21e101183f4..7623811cc11c 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -128,21 +128,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
>         pr_debug("md/raid0:%s: FINAL %d zones\n",
>                  mdname(mddev), conf->nr_strip_zones);
>
> -       if (conf->nr_strip_zones == 1) {
> -               conf->layout = RAID0_ORIG_LAYOUT;
> -       } else if (mddev->layout == RAID0_ORIG_LAYOUT ||
> -                  mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
> -               conf->layout = mddev->layout;
> -       } else if (default_layout == RAID0_ORIG_LAYOUT ||
> -                  default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
> -               conf->layout = default_layout;
> -       } else {
> -               pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
> -                      mdname(mddev));
> -               pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
> -               err = -ENOTSUPP;
> -               goto abort;
> -       }
>         /*
>          * now since we have the hard sector sizes, we can make sure
>          * chunk size is a multiple of that sector size
> @@ -273,6 +258,22 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
>                          (unsigned long long)smallest->sectors);
>         }
>
> +       if (conf->nr_strip_zones == 1 || conf->strip_zone[1].nb_dev == 1) {
> +               conf->layout = RAID0_ORIG_LAYOUT;
> +       } else if (mddev->layout == RAID0_ORIG_LAYOUT ||
> +                  mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
> +               conf->layout = mddev->layout;
> +       } else if (default_layout == RAID0_ORIG_LAYOUT ||
> +                  default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
> +               conf->layout = default_layout;
> +       } else {
> +               pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
> +                      mdname(mddev));
> +               pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
> +               err = -ENOTSUPP;
> +               goto abort;
> +       }
> +
>         pr_debug("md/raid0:%s: done.\n", mdname(mddev));
>         *private_conf = conf;
>
> --
> 2.11.0
>