Add network QoS support for PCP to iscsi initiator.

Make the Ethernet PCP codepoint configurable
for L2 local traffic, to allow lower latency for
iSCSI block IO. This addresses the initiator
side only.

Reviewed by:	mav, trasz, bcr
Sponsored by:	NetApp, Inc.
Differential Revision:	https://reviews.freebsd.org/D26739

sys/dev/iscsi/iscsi_ioctl.h

@@ -71,7 +71,8 @@ struct iscsi_session_conf {
 	char		isc_offload[ISCSI_OFFLOAD_LEN];
 	int		isc_enable;
 	int		isc_dscp;
-	int		isc_spare[3];
+	int		isc_pcp;
+	int		isc_spare[2];
 };
 
 /*

usr.bin/iscsictl/iscsi.conf.5

@@ -155,6 +155,13 @@ and
 codepoints.
 Default is no specified dscp codepoint, which means the default
 of the outgoing interface is used.
+.It Cm pcp
+The 802.1Q Priority CodePoint used for sending packets.
+The PCP can be set to a value in the range between
+.Qq Ar 0
+to
+.Qq Ar 7 .
+When omitted, the default for the outgoing interface is used.
 .El
 .Sh FILES
 .Bl -tag -width indent

usr.bin/iscsictl/iscsictl.c

@@ -88,6 +88,7 @@ target_new(struct conf *conf)
 		xo_err(1, "calloc");
 	targ->t_conf = conf;
 	targ->t_dscp = -1;
+	targ->t_pcp = -1;
 	TAILQ_INSERT_TAIL(&conf->conf_targets, targ, t_next);
 
 	return (targ);
@@ -360,6 +361,7 @@ conf_from_target(struct iscsi_session_conf *conf,
 	else
 		conf->isc_data_digest = ISCSI_DIGEST_NONE;
 	conf->isc_dscp = targ->t_dscp;
+	conf->isc_pcp = targ->t_pcp;
 }
 
 static int
@@ -540,6 +542,9 @@ kernel_list(int iscsi_fd, const struct target *targ __unused,
 			if (conf->isc_dscp != -1)
 				xo_emit("{L:/%-26s}{V:dscp/0x%02x}\n",
 				    "Target DSCP:", conf->isc_dscp);
+			if (conf->isc_pcp != -1)
+				xo_emit("{L:/%-26s}{V:pcp/0x%02x}\n",
+				    "Target PCP:", conf->isc_pcp);
 			xo_close_container("target");
 
 			xo_open_container("auth");

usr.bin/iscsictl/iscsictl.h

@@ -79,6 +79,7 @@ struct target {
 	int			t_enable;
 	int			t_protocol;
 	int			t_dscp;
+	int			t_pcp;
 	char			*t_offload;
 	char			*t_user;
 	char			*t_secret;

usr.bin/iscsictl/parse.y

@@ -133,6 +133,8 @@ target_entry:
 	ignored
 	|
 	dscp
+	|
+	pcp
 	;
 
 target_name:	TARGET_NAME EQUALS STR
@@ -306,6 +308,8 @@ dscp:		DSCP EQUALS STR
 	{
 		uint64_t tmp;
 
+		if (target->t_dscp != -1)
+			xo_errx(1, "duplicated dscp at line %d", lineno);
 		if (strcmp($3, "0x") == 0) {
 			tmp = strtol($3 + 2, NULL, 16);
 		} else if (expand_number($3, &tmp) != 0) {
@@ -344,6 +348,27 @@ dscp:		DSCP EQUALS STR
 	| DSCP EQUALS AF43	{ target->t_dscp = IPTOS_DSCP_AF43 >> 2 ; }
 	;
 
+pcp:	PCP EQUALS STR
+	{
+		uint64_t tmp;
+
+		if (target->t_pcp != -1)
+			xo_errx(1, "duplicated pcp at line %d", lineno);
+
+		if (expand_number($3, &tmp) != 0) {
+			yyerror("invalid numeric value");
+			free($3);
+			return(1);
+		}
+		if (!((tmp >=0) && (tmp <= 7))) {
+			yyerror("invalid pcp value");
+			return(1);
+		}
+
+		target->t_pcp = tmp;
+	}
+	;
+
 %%
 
 void

usr.bin/iscsictl/token.l

@@ -69,6 +69,7 @@ protocol		{ return PROTOCOL; }
 offload			{ return OFFLOAD; }
 port			{ return IGNORED; }
 dscp			{ return DSCP; }
+pcp			{ return PCP; }
 MaxConnections		{ return IGNORED; }
 TargetAlias		{ return IGNORED; }
 TargetPortalGroupTag	{ return IGNORED; }

usr.sbin/iscsid/iscsid.c

@@ -297,6 +297,25 @@ connection_new(int iscsi_fd, const struct iscsi_daemon_request *request)
 				    from_addr);
 		}
 	}
+	if (conn->conn_conf.isc_pcp != -1) {
+		int pcp = conn->conn_conf.isc_pcp;
+		if (to_ai->ai_family == AF_INET) {
+			if (setsockopt(conn->conn_socket,
+			    IPPROTO_IP, IP_VLAN_PCP,
+			    &pcp, sizeof(pcp)) == -1)
+				log_warn("setsockopt(IP_VLAN_PCP) "
+				    "failed for %s",
+				    from_addr);
+		} else
+		if (to_ai->ai_family == AF_INET6) {
+			if (setsockopt(conn->conn_socket,
+			    IPPROTO_IPV6, IPV6_VLAN_PCP,
+			    &pcp, sizeof(pcp)) == -1)
+				log_warn("setsockopt(IPV6_VLAN_PCP) "
+				    "failed for %s",
+				    from_addr);
+		}
+	}
 	if (from_ai != NULL) {
 		error = bind(conn->conn_socket, from_ai->ai_addr,
 		    from_ai->ai_addrlen);