Re: [PATCH 9/9] bsg: split handling of SCSI CDBs vs transport requeues

+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(ptr64(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 = blk_rq_bytes(rq->next_rq);
+
+		if (WARN_ON(job->reply_payload_rcv_len > rsp_len))

This gives my a lot of new Warnings when running my tests on zFCP, non
of which happen when I run on 4.13.

After browsing the source some, I figured this is because in comparison
to the old code, blk_rq_bytes() is now called after we finished the
blk-request already and blk_update_bidi_request()+blk_update_request()
was already called. This will update rq->__data_len, and thus the call
here to get rsp_len will get a wrong value. Thus the warnings, and the
following calculation is actually wrong.

I figure you can just replace this call for blk_rq_bytes() with
'job->reply_payload.payload_len'. Its essentially the same value, but
the later is not changed after the job is committed as far as I could see
in the source. Driver makes use of it, but only reading as far as I
could make out after browsing the code for a bit.

I did a quick test with that change in place and that seems to work fine
now. As far as my tests go, they behave as they did before.


                                                    Beste Gr��e / Best regards,
                                                      - Benjamin Block

+			hdr->din_resid = 0;
+		else
+			hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
+	} else {
+		hdr->din_resid = 0;
+	}
+
+	return ret;
+}
+

--
Linux on z Systems Development         /         IBM Systems & Technology Group
		  IBM Deutschland Research & Development GmbH
Vorsitz. AufsR.: Martina Koederitz     /        Gesch�ftsf�hrung: Dirk Wittkopp
Sitz der Gesellschaft: B�blingen / Registergericht: AmtsG Stuttgart, HRB 243294