peer_req_op
if (peer_req_op(peer_req) == REQ_OP_READ) {
if (!(peer_req_op(peer_req) == REQ_OP_WRITE ||
peer_req_op(peer_req) == REQ_OP_READ)) {
D_ASSERT(peer_device, peer_req_op(peer_req) == REQ_OP_DISCARD);
D_ASSERT(peer_device, peer_req_op(peer_req) == REQ_OP_WRITE_ZEROES);