On 2020/5/16 20:38, Christoph Hellwig wrote: > On Sat, May 16, 2020 at 11:54:31AM +0800, Coly Li wrote: >> For a zoned device, e.g. host managed SMR hard drive, REQ_OP_ZONE_RESET >> is to reset the LBA of a zone's write pointer back to the start LBA of >> this zone. After the write point is reset, all previously stored data >> in this zone is invalid and unaccessible anymore. Therefore, this op >> code changes on disk data, belongs to a WRITE request op code. >> >> Current REQ_OP_ZONE_RESET is defined as number 6, but the convention of >> the op code is, READ requests are even numbers, and WRITE requests are >> odd numbers. See how op_is_write defined, > > The convention is all about data transfer, and zone reset does not > transfer any data. > Yes you are right, just like REQ_OP_DISCARD which does not transfer any data but changes the data on device. If the request changes the stored data, it does transfer data. This is why in patch "block: set bi_size to REQ_OP_ZONE_RESET bio" I set bi_size to the REQ_OP_ZONE_RESET and REQ_OP_ZONE_RESET_ALL bios. Coly Li
