[SCSI] libiscsi: handle immediate command rejections

If we sent multiple pdus as immediate the target could be
rejecting some and we have just been dropping the rejection
notification. This adds code to handle nop-out rejections,
so if a nop-out was sent as a ping and rejected we do not
mark the connection bad. Instead we just clean up the timers
since we have pdu making a rount trip we know the connection
is good.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/libiscsi.c

@@ -857,27 +857,102 @@ static void iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
 	}
 }
 
+static int iscsi_nop_out_rsp(struct iscsi_task *task,
+			     struct iscsi_nopin *nop, char *data, int datalen)
+{
+	struct iscsi_conn *conn = task->conn;
+	int rc = 0;
+
+	if (conn->ping_task != task) {
+		/*
+		 * If this is not in response to one of our
+		 * nops then it must be from userspace.
+		 */
+		if (iscsi_recv_pdu(conn->cls_conn, (struct iscsi_hdr *)nop,
+				   data, datalen))
+			rc = ISCSI_ERR_CONN_FAILED;
+	} else
+		mod_timer(&conn->transport_timer, jiffies + conn->recv_timeout);
+	iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
+	return rc;
+}
+
 static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 			       char *data, int datalen)
 {
 	struct iscsi_reject *reject = (struct iscsi_reject *)hdr;
 	struct iscsi_hdr rejected_pdu;
+	int opcode, rc = 0;
 
 	conn->exp_statsn = be32_to_cpu(reject->statsn) + 1;
 
-	if (reject->reason == ISCSI_REASON_DATA_DIGEST_ERROR) {
-		if (ntoh24(reject->dlength) > datalen)
-			return ISCSI_ERR_PROTO;
+	if (ntoh24(reject->dlength) > datalen ||
+	    ntoh24(reject->dlength) < sizeof(struct iscsi_hdr)) {
+		iscsi_conn_printk(KERN_ERR, conn, "Cannot handle rejected "
+				  "pdu. Invalid data length (pdu dlength "
+				  "%u, datalen %d\n", ntoh24(reject->dlength),
+				  datalen);
+		return ISCSI_ERR_PROTO;
+	}
+	memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
+	opcode = rejected_pdu.opcode & ISCSI_OPCODE_MASK;
 
-		if (ntoh24(reject->dlength) >= sizeof(struct iscsi_hdr)) {
-			memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
-			iscsi_conn_printk(KERN_ERR, conn,
-					  "pdu (op 0x%x) rejected "
-					  "due to DataDigest error.\n",
-					  rejected_pdu.opcode);
+	switch (reject->reason) {
+	case ISCSI_REASON_DATA_DIGEST_ERROR:
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "pdu (op 0x%x itt 0x%x) rejected "
+				  "due to DataDigest error.\n",
+				  rejected_pdu.itt, opcode);
+		break;
+	case ISCSI_REASON_IMM_CMD_REJECT:
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "pdu (op 0x%x itt 0x%x) rejected. Too many "
+				  "immediate commands.\n",
+				  rejected_pdu.itt, opcode);
+		/*
+		 * We only send one TMF at a time so if the target could not
+		 * handle it, then it should get fixed (RFC mandates that
+		 * a target can handle one immediate TMF per conn).
+		 *
+		 * For nops-outs, we could have sent more than one if
+		 * the target is sending us lots of nop-ins
+		 */
+		if (opcode != ISCSI_OP_NOOP_OUT)
+			return 0;
+
+		 if (rejected_pdu.itt == cpu_to_be32(ISCSI_RESERVED_TAG))
+			/*
+			 * nop-out in response to target's nop-out rejected.
+			 * Just resend.
+			 */
+			iscsi_send_nopout(conn,
+					  (struct iscsi_nopin*)&rejected_pdu);
+		else {
+			struct iscsi_task *task;
+			/*
+			 * Our nop as ping got dropped. We know the target
+			 * and transport are ok so just clean up
+			 */
+			task = iscsi_itt_to_task(conn, rejected_pdu.itt);
+			if (!task) {
+				iscsi_conn_printk(KERN_ERR, conn,
+						 "Invalid pdu reject. Could "
+						 "not lookup rejected task.\n");
+				rc = ISCSI_ERR_BAD_ITT;
+			} else
+				rc = iscsi_nop_out_rsp(task,
+					(struct iscsi_nopin*)&rejected_pdu,
+					NULL, 0);
 		}
+		break;
+	default:
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "pdu (op 0x%x itt 0x%x) rejected. Reason "
+				  "code 0x%x\n", rejected_pdu.itt,
+				  rejected_pdu.opcode, reject->reason);
+		break;
 	}
-	return 0;
+	return rc;
 }
 
 /**
@@ -1038,15 +1113,8 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		}
 		conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
 
-		if (conn->ping_task != task)
-			/*
-			 * If this is not in response to one of our
-			 * nops then it must be from userspace.
-			 */
-			goto recv_pdu;
-
-		mod_timer(&conn->transport_timer, jiffies + conn->recv_timeout);
-		iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
+		rc = iscsi_nop_out_rsp(task, (struct iscsi_nopin*)hdr,
+				       data, datalen);
 		break;
 	default:
 		rc = ISCSI_ERR_BAD_OPCODE;