Re: [PATCH v3] super1: fix sb->max_dev when adding a new disk in linear array

[NeilBrown <neilb@suse.com>]

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On Fri, May 19 2017, Lidong Zhong wrote:

> The value of sb->max_dev will always be increased by 1 when adding
> a new disk in linear array. It causes an inconsistence between each
> disk in the array and the "Array State" value of "mdadm --examine DISK"
> is wrong. For example, when adding the first new disk into linear array
> it will be:
>
> Array State : RAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
> ('A' == active, '.' == missing, 'R' == replacing)
>
> Adding the second disk into linear array it will be
>
> Array State : .AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
> ('A' == active, '.' == missing, 'R' == replacing)
>
> Signed-off-by: Lidong Zhong <lzhong@suse.com>
> ---
>  super1.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/super1.c b/super1.c
> index 2fcb814..811923f 100644
> --- a/super1.c
> +++ b/super1.c
> @@ -1267,8 +1267,13 @@ static int update_super1(struct supertype *st, struct mdinfo *info,
>  				break;
>  		sb->dev_number = __cpu_to_le32(i);
>  		info->disk.number = i;
> -		if (max >= __le32_to_cpu(sb->max_dev))
> -			sb->max_dev = __cpu_to_le32(max+1);
> +		if (i >= max) {
> +			while (max <= i) {
> +				sb->dev_roles[max] = __cpu_to_le16(MD_DISK_ROLE_SPARE);
> +				max += 1;
> +			}
> +			sb->max_dev = __cpu_to_le32(max);
> +		}

This part of the patch is OK....

>  
>  		random_uuid(sb->device_uuid);
>  
> @@ -1296,6 +1301,10 @@ static int update_super1(struct supertype *st, struct mdinfo *info,
>  		sb->raid_disks = __cpu_to_le32(info->array.raid_disks);
>  		sb->dev_roles[info->disk.number] =
>  			__cpu_to_le16(info->disk.raid_disk);
> +		if (sb->raid_disks+1 >= __le32_to_cpu(sb->max_dev)) {

sb->raid_disks is an le32 number, not a cpu number.  So adding 1 to
it is clearly wrong.

Why do you think you need a change here at all?

NeilBrown


> +			sb->dev_roles[sb->raid_disks] = __cpu_to_le16(MD_DISK_ROLE_SPARE);
> +			sb->max_dev = __cpu_to_le32(sb->raid_disks+1);
> +		}
>  	} else if (strcmp(update, "resync") == 0) {
>  		/* make sure resync happens */
>  		sb->resync_offset = 0ULL;
> -- 
> 2.12.0

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