Hi Christoph, as discussed yesterday I have picked your first patch, adopted the second one and created a new third patch to remove the ioctl_by_bdev calls. I export the symbol for the dasd_biodasdinfo function and obtain the pointer with a kallsyms_lookup_name. The checking if the gendisk is owned by a DASD is done by comparing the fops pointer as you suggested. Looks like the most suitable method here. Please note that this patch is not ready for inclusion and only basic function tested. It is just for discussion. Christoph Hellwig (2): dasd: refactor dasd_ioctl_information block: add a s390-only biodasdinfo method Stefan Haberland (1): s390/dasd: remove ioctl_by_bdev calls block/partitions/ibm.c | 15 +++++++-- drivers/s390/block/dasd_int.h | 1 + drivers/s390/block/dasd_ioctl.c | 59 ++++++++++++++++++++++++--------- include/linux/blkdev.h | 1 + 4 files changed, 57 insertions(+), 19 deletions(-) -- 2.17.1