Re: [PATCH] md: no longer compare spare disk superblock events in super_load

[Yufen Yu <yuyufen@xxxxxxxxxx>]

On 2019/9/2 15:16, Yufen Yu wrote:
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 24638ccedce4..350e1f152e97 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -1092,7 +1092,7 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
>   {
>   	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
>   	mdp_super_t *sb;
> -	int ret;
> +	int ret = 0;
>   
>   	/*
>   	 * Calculate the position of the superblock (512byte sectors),
> @@ -1160,10 +1160,13 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
>   		}
>   		ev1 = md_event(sb);
>   		ev2 = md_event(refsb);
> -		if (ev1 > ev2)
> -			ret = 1;
> -		else
> -			ret = 0;
> +
> +		/* Insist on good event counter while assembling, except
> +		 * for spares (which don't need an event count) */
> +		if (sb->disks[rdev->desc_nr].state & (
> +			(1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
> +			if (ev1 > ev2)
> +				ret = 1;
>   	}
>   	rdev->sectors = rdev->sb_start;

super_90_load will set 'ret = -EINVAL' before checking event count, as 
follow:

    ret = read_disk_sb(rdev, MD_SB_BYTES);
    if (ret)
        return ret;

    ret = -EINVAL;

So, we cannot write 'if' statement like that, which will  lead to 
super_90_load
return '-EINVAL' for spare disks. Then, test cases in mdadm , such as 
00linear, 00raid0,
will report failed.

I will resend the fixed version.

Thanks,
Yufen