From: Stefan Sperling <stsp@stsp.name>
Subject: Re: [patch] [ok?] bioctl: disallow -c 1C with only one chunk (as per man page)
To: Alexander Klimov <a@kli.mov>
Cc: tech@openbsd.org
Date: Fri, 26 Apr 2024 11:53:01 +0200

On Fri, Apr 26, 2024 at 11:12:18AM +0200, Alexander Klimov wrote:
> Hello everyone!
> 
> bioctl(8) clearly states that "The RAID 1C discipline
> requires a minimum of two chunks when a new volume is created".
> 
> However, bio_createraid() in /usr/src/sbin/bioctl/bioctl.c requires
> only min_disks = 1; for 1C, allowing me a "bioctl -c 1C -l sdXY softraid0".
> 
> Luckily the kernel complains with "softraid0: RAID 1C requires two or more chunks".
> 
> The attached diff lets /sbin/bioctl complain with "bioctl: not enough disks".
> Ok?

Not ok, this was done on purpose.
With your diff there is no way to recover from a broken chunk.

> --- /usr/src/sbin/bioctl/bioctl.c
> +++ /usr/src/sbin/bioctl/bioctl.c
> @@ -857,8 +857,10 @@
>  		min_disks = 3;
>  		break;
>  	case 'C':
> -	case 0x1C:
>  		min_disks = 1;
> +		break;
> +	case 0x1C:
> +		min_disks = 2;
>  		break;
>  	case 'c':
>  		min_disks = 1;