Re: [PATCH 1/1] s390/dasd: remove ioctl_by_bdev from DASD driver

[Christoph Hellwig]

On Tue, May 05, 2020 at 05:09:56PM +0200, Stefan Haberland wrote:
> OK, thanks for the hint.I did not have this in mind. And I still have
> to look up how this is working at all.
> But isn't this only a real issue for devices with more than 16 minors
> or partitions? So it should not be a problem for DASDs with our limit
> of 3 partitions and the fixed amount of minors, right?
> 
> Just tested with CONFIG_DEBUG_BLOCK_EXT_DEVT enabled and about 1000
> unlabeled devices. Did not see an issue.
> 
> While I see the SCSI devices with MAJOR 259 and quite a random MINOR
> all the DASD devices keep their MAJOR 94 and ascending MINOR.

Looks like it only changes the minors, and not the majors.  Still
checking for major and relying on a shared structure define in different
places just doesn't look maintainable.

> > And compared to all the complications I think the biodasdinfo method
> > is the least of all those evils.
> 
> Are you talking about your first patch suggestion?Then I disagree.
> I still do not like to force the driver to be built in if there is an
> alternative.

No, I mean the series that I actually sent out:

https://lkml.org/lkml/2020/4/21/66
https://lkml.org/lkml/2020/4/21/68
https://lkml.org/lkml/2020/4/21/69