On Tue, Oct 21, 2014 at 08:48:26AM -0400, Mike Snitzer wrote:

quoted

-	memset(sb + sizeof(*sb), 0, rdev->sb_size - sizeof(*sb));
+	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
 
 	sb->magic = cpu_to_le32(DM_RAID_MAGIC);
 	sb->features = cpu_to_le32(0);	/* No features yet */

Not following... sizeof(*sb) != sizeof(sb).  So I'm not seeing a
problem.

Nor am I seeing how you think sb + 1 is equivalent to what Heinz
intended (zero the memory following the sizeof(struct dm_raid_superblock)).

It's pointer math.

sizeof(*sb) is 512.

"sb + sizeof(*sb)" is the same as (void *)sb + 512 * 512.
"sb + 1" is the same as (void *)sb + 512.

regards,
dan carpenter