block ioctl cleanups v2

[Christoph Hellwig]

On Wed, Nov 11, 2020 at 09:13:05AM -0700, Jens Axboe wrote:
> On 11/11/20 12:58 AM, Christoph Hellwig wrote:
> > Jens, can you take a look and possibly pick this series up?
> 
> Looks good to me - but what is the final resolution on the BLKROSET
> propagation?

Do it properly including a hard read only flag.  Martin has an old
patch that I'm going to forward port.  For now I think we need to
adjust dasd to match the behavior of all drivers, so that we can fix
the common code to behave more like dasd in the next step.