nvme_to_user_ptr
ret = blk_rq_map_user_io(req, NULL, nvme_to_user_ptr(ubuffer),
if (nvme_to_user_ptr(io.metadata))
metadata = nvme_to_user_ptr(io.metadata);
cmd.addr, cmd.data_len, nvme_to_user_ptr(cmd.metadata),
cmd.addr, cmd.data_len, nvme_to_user_ptr(cmd.metadata),
nvme_to_user_ptr(d.metadata), d.metadata_len,