On Mon, 19 Apr 2021, Damien Le Moal wrote: > > I would say that it is incompatible with all dm targets - even the linear > > target is changing the sector number and so it may redirect the write > > outside of the range specified in dm-table and cause corruption. > > DM remapping of BIO sectors is zone compatible because target entries must be > zone aligned. In the case of zone append, the BIO sector always point to the > start sector of the target zone. DM sector remapping will remap that to another > zone start as all zones are the same size. No issue here. We extensively use > dm-linear for various test environment to reduce the size of the device tested > (to speed up tests). I am confident there are no problems there. > > > Instead of complicating device mapper with imperfect support, I would just > > disable REQ_OP_ZONE_APPEND on device mapper at all. > > That was my initial approach, but for dm-crypt only since other targets that > support zoned devices are fine. However, this breaks zoned block device > requirement that zone append be supported so that users are presented with a > uniform interface for different devices. So while simple to do, disabling zone > append is far from ideal. So, we could enable it for the linear target and disable for all other targets? I talked with Milan about it and he doesn't want to add more bloat to the crypt target. I agree with him. Mikulas
