+#include <scsi/sg.h>
+
+#define uptr64(val) ((void __user *)(uintptr_t)(val))
+
+static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
+{
+ if (hdr->protocol != BSG_PROTOCOL_SCSI ||
+ hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
+ return -EINVAL;
+ if (!capable(CAP_SYS_RAWIO))
+ return -EPERM;
+ return 0;
+}
+
+static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
+ fmode_t mode)
+{
+ struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+
+ job->request_len = hdr->request_len;
+ job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
+ if (IS_ERR(job->request))
+ return PTR_ERR(job->request);
+ return 0;
+}
+
+static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
+{
+ struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+ int ret = 0;
+
+ /*
+ * The assignments below don't make much sense, but are kept for
+ * bug by bug backwards compatibility:
+ */
+ hdr->device_status = job->result & 0xff;
+ hdr->transport_status = host_byte(job->result);
+ hdr->driver_status = driver_byte(job->result);
+ hdr->info = 0;
+ if (hdr->device_status || hdr->transport_status || hdr->driver_status)
+ hdr->info |= SG_INFO_CHECK;
+ hdr->response_len = 0;
+
+ if (job->result < 0) {
+ /* we're only returning the result field in the reply */
+ job->reply_len = sizeof(u32);
+ ret = job->result;
+ }
+
+ if (job->reply_len && hdr->response) {
+ int len = min(hdr->max_response_len, job->reply_len);
+
+ if (copy_to_user(uptr64(hdr->response), job->reply, len))
+ ret = -EFAULT;
+ else
+ hdr->response_len = len;
+ }
+
+ /* we assume all request payload was transferred, residual == 0 */
+ hdr->dout_resid = 0;
+
+ if (rq->next_rq) {
+ unsigned int rsp_len = job->reply_payload.payload_len;
+
+ if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
+ hdr->din_resid = 0;
+ else
+ hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
+ } else {
+ hdr->din_resid = 0;
+ }
+
+ return ret;
+}
+
+static void bsg_transport_free_rq(struct request *rq)
+{
+ struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+
+ kfree(job->request);
+}
+
+static const struct bsg_ops bsg_transport_ops = {
+ .check_proto = bsg_transport_check_proto,
+ .fill_hdr = bsg_transport_fill_hdr,
+ .complete_rq = bsg_transport_complete_rq,
+ .free_rq = bsg_transport_free_rq,
+};