atatat@atatdot.net said:
> this is a fascinating idea

A good idea, agreed, but imho committed a bit too quickly.
If you look at the SCSI specs - there is a distinction between
a "primary" and a "grown" defect list.
One might want to make intelligent use of the related SCSI commands
as "reassign block", and the defect list read commands; it would
need means to control this.
The ioctl data format should be fixed byte size, so that the list
can be saved somewhere to survive reboots.
So I'd say this needs some thoughts and study of prior art before
the interface is set in stone.

best regards
Matthias