[adding Chaitanya to Cc] On Fri, Oct 28, 2016 at 07:43:41AM -0400, Mikulas Patocka wrote: > We could detect if the REQ_OP_WRITE_SAME command contains all zeroes and > if it does, turn it into "Write Zeroes" or TRIM command (if the device > guarantees zeroing on trim). If it doesn't contain all zeroes and the > device doesn't support non-zero WRITE SAME, then reject it. I don't like this because it's very inefficient - we have to allocate a payload first and then compare the whole payload for very operation. > Or maybe we could add a new command REQ_OP_WRITE_ZEROES - I'm not sure > which of these two possibilities is better. Chaitanya actually did an initial prototype implementation of this for NVMe that he shared with me. I liked it a lot and I think he'll be ready to post it in a few days. Now that we have the REQ_OP* values instead of mapping different command types to flags it's actually surprisingly easy to add new block layer operations. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
