Comment 7 for bug 1845323

Christian, I took the patch and applied it to what's currently in Eoan (19.10) master-next.
It applied cleanly and it compiled fine and I installed it in z/VM guest that I installed on FCP.
Afterwards I was able to enable add. DASDs from there with chzdev:

buntu@hwe0006:~$ sudo chzdev -e 200
ECKD DASD 0.0.0200 configured

ubuntu@hwe0006:~$ lszdev dasd | grep yes
dasd-eckd 0.0.0200 yes yes dasda

I thought I go ahead and create a proper file-system:

ubuntu@hwe0006:~$ sudo dasdfmt -b 4096 /dev/dasda
Drive Geometry: 10016 Cylinders * 15 Heads = 150240 Tracks
Device Type: Fully Provisioned

I am going to format the device /dev/dasda in the following way:
   Device number of device : 0x200
   Labelling device : yes
   Disk label : VOL1
   Disk identifier : 0X0200
   Extent start (trk no) : 0
   Extent end (trk no) : 150239
   Compatible Disk Layout : yes
   Blocksize : 4096
   Mode : Full

--->> ATTENTION! <<---
All data of that device will be lost.
Type "yes" to continue, no will leave the disk untouched: yes
Formatting the device. This may take a while (get yourself a coffee).

Finished formatting the device.
Rereading the partition table... ok
ubuntu@hwe0006:~$ sudo fdasd -a /dev/dasda
reading volume label ..: VOL1
reading vtoc ..........: ok

auto-creating one partition for the whole disk...
writing volume label...
writing VTOC...
rereading partition table...
ubuntu@hwe0006:~$ sudo mkfs.ext4 /dev/dasda
dasda dasda1
ubuntu@hwe0006:~$ sudo mkfs.ext4 /dev/dasda1
mke2fs 1.45.3 (14-Jul-2019)
Creating filesystem with 1802856 4k blocks and 451584 inodes
Filesystem UUID: 63b8ea83-a707-42a7-bec2-16ee956eea30
Superblock backups stored on blocks:
 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

ubuntu@hwe0006:~$

So it looks pretty good.
(Now need to regression test on further environments ...)

Thanks for the quick turn-around Jan, Stefan and Christian!