On Sat, 17 Apr 2021, Damien Le Moal wrote: > Mike, > > Zone append BIOs (REQ_OP_ZONE_APPEND) always specify the start sector > of the zone to be written instead of the actual location sector to > write. The write location is determined by the device and returned to > the host upon completion of the operation. I'd like to ask what's the reason for this semantics? Why can't users of the zoned device supply real sector numbers? > This interface, while simple and efficient for writing into sequential > zones of a zoned block device, is incompatible with the use of sector > values to calculate a cypher block IV. All data written in a zone is > encrypted using an IV calculated from the first sectors of the zone, > but read operation will specify any sector within the zone, resulting > in an IV mismatch between encryption and decryption. Reads fail in that > case. 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. Instead of complicating device mapper with imperfect support, I would just disable REQ_OP_ZONE_APPEND on device mapper at all. Mikulas
