On Mon, Mar 19, 2018 at 07:36:50PM +0100, Jonas Rabenstein wrote:

Allow modification of the shadow mbr. If the shadow mbr is not marked as
done, this data will be presented read only as the device content. Only
after marking the shadow mbr as done and unlocking a locking range the
actual content is accessible.

I hate doing this as an ioctls.  Can we make this a sysfs binary file
so that people can use dd or cat to write the shadow mbr?