Re: [PATCH v2] md/raid1: prioritize adding disk to 'removed' mirror

[Song Liu]

On Tue, Jun 27, 2023 at 9:44 AM <linan666@xxxxxxxxxxxxxxx> wrote:
>
> From: Li Nan <linan122@xxxxxxxxxx>
>
> New disk should be added to "removed" position first instead of to be a
> replacement. Commit 6090368abcb4 ("md/raid10: prioritize adding disk to
> 'removed' mirror") has fixed this issue for raid10. Fix it for raid1 now.
>
> Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
> Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>

Applied to md-next. Thanks!

Song

> ---
> Changes in v2:
>  - improve commit log.
>
>  drivers/md/raid1.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 68a9e2d9985b..320bede4bfab 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1782,7 +1782,7 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  {
>         struct r1conf *conf = mddev->private;
>         int err = -EEXIST;
> -       int mirror = 0;
> +       int mirror = 0, repl_slot = -1;
>         struct raid1_info *p;
>         int first = 0;
>         int last = conf->raid_disks - 1;
> @@ -1825,17 +1825,21 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>                         break;
>                 }
>                 if (test_bit(WantReplacement, &p->rdev->flags) &&
> -                   p[conf->raid_disks].rdev == NULL) {
> -                       /* Add this device as a replacement */
> -                       clear_bit(In_sync, &rdev->flags);
> -                       set_bit(Replacement, &rdev->flags);
> -                       rdev->raid_disk = mirror;
> -                       err = 0;
> -                       conf->fullsync = 1;
> -                       rcu_assign_pointer(p[conf->raid_disks].rdev, rdev);
> -                       break;
> -               }
> +                   p[conf->raid_disks].rdev == NULL && repl_slot < 0)
> +                       repl_slot = mirror;
>         }
> +
> +       if (err && repl_slot >= 0) {
> +               /* Add this device as a replacement */
> +               p = conf->mirrors + repl_slot;
> +               clear_bit(In_sync, &rdev->flags);
> +               set_bit(Replacement, &rdev->flags);
> +               rdev->raid_disk = repl_slot;
> +               err = 0;
> +               conf->fullsync = 1;
> +               rcu_assign_pointer(p[conf->raid_disks].rdev, rdev);
> +       }
> +
>         print_conf(conf);
>         return err;
>  }
> --
> 2.39.2
>