admin_passthru truncates req/rsp data

[NateThornton]

There's a bug in the pax_nvme_submit_admin_passthru; any data sent/received greater than 1016 bytes will be truncated, with no support to retrieve the remaining bytes.

int pax_nvme_submit_admin_passthru(int fd, struct nvme_passthru_cmd *cmd)
{
	int ret;

	struct pax_nvme_device *pax;
	struct switchtec_device_manage_nvme_req req;
	struct switchtec_device_manage_nvme_rsp rsp;
	int data_len;

	[...]
	
	/* Truncation takes place here, without warning the user*/
	if (cmd->data_len > sizeof(req.nvme_data))
		data_len = sizeof(req.nvme_data);
	else
		data_len = cmd->data_len;
	
	
	/* Request data possibly truncated */
	memcpy(req.nvme_data, (void *)cmd->addr, data_len); 

	[...]

	status = (rsp.nvme_cqe[3] & 0xfffe0000) >> 17;
	if (!status) {
		cmd->result = rsp.nvme_cqe[0];
		if (cmd->addr) {
			/* Response data possibly truncated */
			memcpy((uint64_t *)cmd->addr,
				rsp.nvme_data,
				rsp.hdr.rsp_len - 4 * 4);
		}
	}

	return status;
}

I think this is a limitation of switchtec_device_manage_nvme_req / switchtec_device_manage_nvme_rsp, originating at MRPC_MAX_DATA_LEN Support will need to be added to switchtec-user, but for right now there is no warning or error that the response data is truncated. It is entirely transparent to the user and very error prone.