Am 30.04.20 um 16:02 schrieb Stefan Haberland: > Am 30.04.20 um 15:13 schrieb Christoph Hellwig: >> On Thu, Apr 30, 2020 at 01:17:54PM +0200, Stefan Haberland wrote: >>> Remove the calls to ioctl_by_bdev from the DASD partition detection code >>> to enable the removal of the specific code. >>> >>> To do so reuse the gendisk private_data pointer and not only provide a >>> pointer to the devmap but provide a new structure containing a pointer >>> to the devmap as well as all required information for the partition >>> detection. This makes it independent from the dasd_information2_t >>> structure. >> I think sharing the data structure in private data is pretty dangerous. > Thought of this as well. This is why I check for the major number before I > use the private pointer to reference the data structure. Thought this would > be enough checking. > Do you think this is not sufficient? > >> In the meantime I thought of another idea - the partition code could >> do a symbol_get of a symbol exported by the dasd driver and use that >> to query the information. > Then I would need to export a lot of DASD internal structures to be > available > in thepartition detection code if I would like to walk down our device > map to > findthe corresponding device for example. Not sure if this is that easy. I did some additional research on this. What I could imagine: The gendisk->private_data pointer currently contains a pointer to the dasd_devmap structure. This one is also reachable by iterating over an exported dasd_hashlist. So I could export the dasd_hashlist symbol, iterate over it and try to find the dasd_devmap pointer I have from the gendisk->private_data pointer. This would ensure that the gendisk belongs to the DASD driver and I could use the additional information that is somehow reachable through the gendisk->private_data pointer. But again, I am not sure if this additional code and effort is needed. >From my point of view checking the gendisk->major for DASD_MAJOR is OK to ensure that the device belongs to the DASD driver. What do you think?
