[SCSI] iscsi: increment expstatsn during login

debugged by Ming and Rohan:

The problem Ming and Rohan debugged was that during a normal session
login, open-iscsi is not incrementing the exp_statsn counter. It was
stuck at zero. From the RFC, it looks like if the login response PDU has
a successful status then we should be incrementing that value. Also from
the RFC, it looks like if when we drop a connection then reconnect, we
should be using the exp_statsn from the old connection in the next
relogin attempt.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/iscsi_tcp.c

@@ -2298,6 +2298,9 @@ iscsi_conn_set_param(struct iscsi_cls_conn *cls_conn, enum iscsi_param param,
 		BUG_ON(value);
 		session->ofmarker_en = value;
 		break;
+	case ISCSI_PARAM_EXP_STATSN:
+		conn->exp_statsn = value;
+		break;
 	default:
 		break;
 	}
@@ -2381,6 +2384,9 @@ iscsi_conn_get_param(struct iscsi_cls_conn *cls_conn,
 		inet = inet_sk(tcp_conn->sock->sk);
 		*value = be16_to_cpu(inet->dport);
 		mutex_unlock(&conn->xmitmutex);
+	case ISCSI_PARAM_EXP_STATSN:
+		*value = conn->exp_statsn;
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -2548,7 +2554,8 @@ static struct iscsi_transport iscsi_tcp_transport = {
 				  ISCSI_DATASEQ_INORDER_EN |
 				  ISCSI_ERL |
 				  ISCSI_CONN_PORT |
-				  ISCSI_CONN_ADDRESS,
+				  ISCSI_CONN_ADDRESS |
+				  ISCSI_EXP_STATSN,
 	.host_template		= &iscsi_sht,
 	.conndata_size		= sizeof(struct iscsi_conn),
 	.max_conn		= 1,

drivers/scsi/libiscsi.c

@@ -333,15 +333,21 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		debug_scsi("immrsp [op 0x%x cid %d itt 0x%x len %d]\n",
 			   opcode, conn->id, mtask->itt, datalen);
 
-		switch(opcode) {
-		case ISCSI_OP_LOGIN_RSP:
-		case ISCSI_OP_TEXT_RSP:
-		case ISCSI_OP_LOGOUT_RSP:
 		rc = iscsi_check_assign_cmdsn(session,
 					      (struct iscsi_nopin*)hdr);
 		if (rc)
-				break;
+			goto done;
 
+		switch(opcode) {
+		case ISCSI_OP_LOGOUT_RSP:
+			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
+			/* fall through */
+		case ISCSI_OP_LOGIN_RSP:
+		case ISCSI_OP_TEXT_RSP:
+			/*
+			 * login related PDU's exp_statsn is handled in
+			 * userspace
+			 */
 			rc = iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen);
 			list_del(&mtask->running);
 			if (conn->login_mtask != mtask)
@@ -349,15 +355,12 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 					    (void*)&mtask, sizeof(void*));
 			break;
 		case ISCSI_OP_SCSI_TMFUNC_RSP:
-			rc = iscsi_check_assign_cmdsn(session,
-						 (struct iscsi_nopin*)hdr);
-			if (rc)
-				break;
-
 			if (datalen) {
 				rc = ISCSI_ERR_PROTO;
 				break;
 			}
+
+			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
 			conn->tmfrsp_pdus_cnt++;
 			if (conn->tmabort_state == TMABORT_INITIAL) {
 				conn->tmabort_state =
@@ -373,10 +376,6 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 				rc = ISCSI_ERR_PROTO;
 				break;
 			}
-			rc = iscsi_check_assign_cmdsn(session,
-						(struct iscsi_nopin*)hdr);
-			if (rc)
-				break;
 			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
 
 			rc = iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen);
@@ -404,6 +403,7 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		case ISCSI_OP_REJECT:
 			/* we need sth like iscsi_reject_rsp()*/
 		case ISCSI_OP_ASYNC_EVENT:
+			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
 			/* we need sth like iscsi_async_event_rsp() */
 			rc = ISCSI_ERR_BAD_OPCODE;
 			break;
@@ -414,6 +414,7 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	} else
 		rc = ISCSI_ERR_BAD_ITT;
 
+done:
 	return rc;
 }
 EXPORT_SYMBOL_GPL(__iscsi_complete_pdu);
@@ -730,6 +731,7 @@ iscsi_conn_send_generic(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	        BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE);
 	        BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED);
 
+		nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
 		if (!__kfifo_get(session->mgmtpool.queue,
 				 (void*)&mtask, sizeof(void*))) {
 			spin_unlock_bh(&session->lock);
@@ -738,7 +740,7 @@ iscsi_conn_send_generic(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	}
 
 	/*
-	 * pre-format CmdSN and ExpStatSN for outgoing PDU.
+	 * pre-format CmdSN for outgoing PDU.
 	 */
 	if (hdr->itt != cpu_to_be32(ISCSI_RESERVED_TAG)) {
 		hdr->itt = mtask->itt | (conn->id << ISCSI_CID_SHIFT) |
@@ -751,8 +753,6 @@ iscsi_conn_send_generic(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		/* do not advance CmdSN */
 		nop->cmdsn = cpu_to_be32(session->cmdsn);
 
-	nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
-
 	if (data_size) {
 		memcpy(mtask->data, data, data_size);
 		mtask->data_count = data_size;
@@ -1647,7 +1647,7 @@ void iscsi_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
 	case STOP_CONN_RECOVER:
 	case STOP_CONN_TERM:
 		iscsi_start_session_recovery(session, conn, flag);
-		return;
+		break;
 	case STOP_CONN_SUSPEND:
 		if (session->tt->suspend_conn_recv)
 			session->tt->suspend_conn_recv(conn);

drivers/scsi/scsi_transport_iscsi.c

@@ -32,7 +32,7 @@
 #include <scsi/iscsi_if.h>
 
 #define ISCSI_SESSION_ATTRS 11
-#define ISCSI_CONN_ATTRS 10
+#define ISCSI_CONN_ATTRS 11
 #define ISCSI_HOST_ATTRS 0
 
 struct iscsi_internal {
@@ -1156,6 +1156,7 @@ iscsi_conn_int_attr(ifmarker, ISCSI_PARAM_IFMARKER_EN, "%d");
 iscsi_conn_int_attr(ofmarker, ISCSI_PARAM_OFMARKER_EN, "%d");
 iscsi_conn_int_attr(persistent_port, ISCSI_PARAM_PERSISTENT_PORT, "%d");
 iscsi_conn_int_attr(port, ISCSI_PARAM_CONN_PORT, "%d");
+iscsi_conn_int_attr(exp_statsn, ISCSI_PARAM_EXP_STATSN, "%u");
 
 #define iscsi_conn_str_attr_show(param)					\
 static ssize_t								\
@@ -1406,6 +1407,7 @@ iscsi_register_transport(struct iscsi_transport *tt)
 	SETUP_CONN_RD_ATTR(ofmarker, ISCSI_OFMARKER_EN);
 	SETUP_CONN_RD_ATTR(address, ISCSI_CONN_ADDRESS);
 	SETUP_CONN_RD_ATTR(port, ISCSI_CONN_PORT);
+	SETUP_CONN_RD_ATTR(exp_statsn, ISCSI_EXP_STATSN);
 
 	if (tt->param_mask & ISCSI_PERSISTENT_ADDRESS)
 		SETUP_CONN_RD_ATTR(persistent_address, ISCSI_PERSISTENT_ADDRESS);

include/scsi/iscsi_if.h

@@ -188,6 +188,7 @@ enum iscsi_param {
 	ISCSI_PARAM_ERL,
 	ISCSI_PARAM_IFMARKER_EN,
 	ISCSI_PARAM_OFMARKER_EN,
+	ISCSI_PARAM_EXP_STATSN,
 	ISCSI_PARAM_TARGET_NAME,
 	ISCSI_PARAM_TPGT,
 	ISCSI_PARAM_PERSISTENT_ADDRESS,
@@ -216,6 +217,7 @@ enum iscsi_param {
 #define ISCSI_ERL			(1 << ISCSI_PARAM_ERL)
 #define ISCSI_IFMARKER_EN		(1 << ISCSI_PARAM_IFMARKER_EN)
 #define ISCSI_OFMARKER_EN		(1 << ISCSI_PARAM_OFMARKER_EN)
+#define ISCSI_EXP_STATSN		(1 << ISCSI_PARAM_EXP_STATSN)
 #define ISCSI_TARGET_NAME		(1 << ISCSI_PARAM_TARGET_NAME)
 #define ISCSI_TPGT			(1 << ISCSI_PARAM_TPGT)
 #define ISCSI_PERSISTENT_ADDRESS	(1 << ISCSI_PARAM_PERSISTENT_ADDRESS)