Re: [PATCH 1/1] mdadm/bitmap: locate bitmap calcuate bitmap position wrongly

["heming.zhao@suse.com" <heming.zhao@suse.com>]

Hello Xiao,

My review comment:
You code only work in modern system. the boundary is 4k not 512, because using hardcode 4k to call calc_bitmap_size

In current cluster env, if bitmap area beyond 4K size (or 512 in very old system), locate_bitmap1 
will return wrong address.

Please refer write_bitmap1() to saparate 512 & 4096 case.

On 10/28/20 2:04 PM, Xiao Ni wrote:
> Now it only adds bitmap offset based on cluster nodes. It's not right. It needs to
> add per node bitmap space to find next node bitmap position.
> 
> Signed-off-by: Xiao Ni <xni@redhat.com>
> ---
>   super1.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/super1.c b/super1.c
> index 8b0d6ff..b5b379b 100644
> --- a/super1.c
> +++ b/super1.c
> @@ -2582,8 +2582,9 @@ add_internal_bitmap1(struct supertype *st,
>   
>   static int locate_bitmap1(struct supertype *st, int fd, int node_num)
>   {
> -	unsigned long long offset;
> +	unsigned long long offset, bm_sectors_per_node;
>   	struct mdp_superblock_1 *sb;
> +	bitmap_super_t *bms;
>   	int mustfree = 0;
>   	int ret;
>   
> @@ -2598,8 +2599,13 @@ static int locate_bitmap1(struct supertype *st, int fd, int node_num)
>   		ret = 0;
>   	else
>   		ret = -1;
> -	offset = __le64_to_cpu(sb->super_offset);
> -	offset += (int32_t) __le32_to_cpu(sb->bitmap_offset) * (node_num + 1);
> +
> +	offset = __le64_to_cpu(sb->super_offset) + __le32_to_cpu(sb->bitmap_offset);
> +	if (node_num) {
> +		bms = (bitmap_super_t*)(((char*)sb)+MAX_SB_SIZE);
> +		bm_sectors_per_node = calc_bitmap_size(bms, 4096) >> 9;
> +		offset += bm_sectors_per_node * node_num;
> +	}
>   	if (mustfree)
>   		free(sb);
>   	lseek64(fd, offset<<9, 0);
>