diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index 502aca27775a36..3f5b752a0eef85 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -407,6 +407,9 @@ SYSCTL_INT(_kern_cam_ctl, OID_AUTO, worker_threads, CTLFLAG_RDTUN,
 static int ctl_debug = CTL_DEBUG_NONE;
 SYSCTL_INT(_kern_cam_ctl, OID_AUTO, debug, CTLFLAG_RWTUN,
     &ctl_debug, 0, "Enabled debug flags");
+static int ctl_lun_map_size = 1024;
+SYSCTL_INT(_kern_cam_ctl, OID_AUTO, lun_map_size, CTLFLAG_RWTUN,
+    &ctl_lun_map_size, 0, "Size of per-port LUN map (max LUN + 1)");
 
 /*
  * Supported pages (0x00), Serial number (0x80), Device ID (0x83),
@@ -826,7 +829,7 @@ ctl_isc_announce_port(struct ctl_port *port)
 		return;
 	i = sizeof(msg->port) + strlen(port->port_name) + 1;
 	if (port->lun_map)
-		i += sizeof(uint32_t) * CTL_MAX_LUNS;
+		i += port->lun_map_size * sizeof(uint32_t);
 	if (port->port_devid)
 		i += port->port_devid->len;
 	if (port->target_devid)
@@ -846,7 +849,7 @@ ctl_isc_announce_port(struct ctl_port *port)
 	    "%d:%s", softc->ha_id, port->port_name) + 1;
 	i += msg->port.name_len;
 	if (port->lun_map) {
-		msg->port.lun_map_len = sizeof(uint32_t) * CTL_MAX_LUNS;
+		msg->port.lun_map_len = port->lun_map_size * sizeof(uint32_t);
 		memcpy(&msg->port.data[i], port->lun_map,
 		    msg->port.lun_map_len);
 		i += msg->port.lun_map_len;
@@ -1155,19 +1158,25 @@ ctl_isc_port_sync(struct ctl_softc *softc, union ctl_ha_msg *msg, int len)
 	    M_CTL);
 	i += msg->port.name_len;
 	if (msg->port.lun_map_len != 0) {
-		if (port->lun_map == NULL)
-			port->lun_map = malloc(sizeof(uint32_t) * CTL_MAX_LUNS,
+		if (port->lun_map == NULL ||
+		    port->lun_map_size * sizeof(uint32_t) <
+		    msg->port.lun_map_len) {
+			port->lun_map_size = 0;
+			free(port->lun_map, M_CTL);
+			port->lun_map = malloc(msg->port.lun_map_len,
 			    M_CTL, M_WAITOK);
-		memcpy(port->lun_map, &msg->port.data[i],
-		    sizeof(uint32_t) * CTL_MAX_LUNS);
+		}
+		memcpy(port->lun_map, &msg->port.data[i], msg->port.lun_map_len);
+		port->lun_map_size = msg->port.lun_map_len / sizeof(uint32_t);
 		i += msg->port.lun_map_len;
 	} else {
+		port->lun_map_size = 0;
 		free(port->lun_map, M_CTL);
 		port->lun_map = NULL;
 	}
 	if (msg->port.port_devid_len != 0) {
 		if (port->port_devid == NULL ||
-		    port->port_devid->len != msg->port.port_devid_len) {
+		    port->port_devid->len < msg->port.port_devid_len) {
 			free(port->port_devid, M_CTL);
 			port->port_devid = malloc(sizeof(struct ctl_devid) +
 			    msg->port.port_devid_len, M_CTL, M_WAITOK);
@@ -1182,7 +1191,7 @@ ctl_isc_port_sync(struct ctl_softc *softc, union ctl_ha_msg *msg, int len)
 	}
 	if (msg->port.target_devid_len != 0) {
 		if (port->target_devid == NULL ||
-		    port->target_devid->len != msg->port.target_devid_len) {
+		    port->target_devid->len < msg->port.target_devid_len) {
 			free(port->target_devid, M_CTL);
 			port->target_devid = malloc(sizeof(struct ctl_devid) +
 			    msg->port.target_devid_len, M_CTL, M_WAITOK);
@@ -1197,7 +1206,7 @@ ctl_isc_port_sync(struct ctl_softc *softc, union ctl_ha_msg *msg, int len)
 	}
 	if (msg->port.init_devid_len != 0) {
 		if (port->init_devid == NULL ||
-		    port->init_devid->len != msg->port.init_devid_len) {
+		    port->init_devid->len < msg->port.init_devid_len) {
 			free(port->init_devid, M_CTL);
 			port->init_devid = malloc(sizeof(struct ctl_devid) +
 			    msg->port.init_devid_len, M_CTL, M_WAITOK);
@@ -3295,7 +3304,7 @@ ctl_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag,
 
 			if (port->lun_map != NULL) {
 				sbuf_printf(sb, "\t<lun_map>on</lun_map>\n");
-				for (j = 0; j < CTL_MAX_LUNS; j++) {
+				for (j = 0; j < port->lun_map_size; j++) {
 					plun = ctl_lun_map_from_port(port, j);
 					if (plun == UINT32_MAX)
 						continue;
@@ -3375,7 +3384,7 @@ ctl_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag,
 			}
 		}
 		mtx_unlock(&softc->ctl_lock); // XXX: port_enable sleeps
-		if (lm->plun < CTL_MAX_LUNS) {
+		if (lm->plun != UINT32_MAX) {
 			if (lm->lun == UINT32_MAX)
 				retval = ctl_lun_map_unset(port, lm->plun);
 			else if (lm->lun < CTL_MAX_LUNS &&
@@ -3383,13 +3392,12 @@ ctl_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag,
 				retval = ctl_lun_map_set(port, lm->plun, lm->lun);
 			else
 				return (ENXIO);
-		} else if (lm->plun == UINT32_MAX) {
+		} else {
 			if (lm->lun == UINT32_MAX)
 				retval = ctl_lun_map_deinit(port);
 			else
 				retval = ctl_lun_map_init(port);
-		} else
-			return (ENXIO);
+		}
 		if (port->status & CTL_PORT_STATUS_ONLINE)
 			ctl_isc_announce_port(port);
 		break;
@@ -3442,15 +3450,20 @@ ctl_lun_map_init(struct ctl_port *port)
 {
 	struct ctl_softc *softc = port->ctl_softc;
 	struct ctl_lun *lun;
+	int size = ctl_lun_map_size;
 	uint32_t i;
 
-	if (port->lun_map == NULL)
-		port->lun_map = malloc(sizeof(uint32_t) * CTL_MAX_LUNS,
+	if (port->lun_map == NULL || port->lun_map_size < size) {
+		port->lun_map_size = 0;
+		free(port->lun_map, M_CTL);
+		port->lun_map = malloc(size * sizeof(uint32_t),
 		    M_CTL, M_NOWAIT);
+	}
 	if (port->lun_map == NULL)
 		return (ENOMEM);
-	for (i = 0; i < CTL_MAX_LUNS; i++)
+	for (i = 0; i < size; i++)
 		port->lun_map[i] = UINT32_MAX;
+	port->lun_map_size = size;
 	if (port->status & CTL_PORT_STATUS_ONLINE) {
 		if (port->lun_disable != NULL) {
 			STAILQ_FOREACH(lun, &softc->lun_list, links)
@@ -3469,6 +3482,7 @@ ctl_lun_map_deinit(struct ctl_port *port)
 
 	if (port->lun_map == NULL)
 		return (0);
+	port->lun_map_size = 0;
 	free(port->lun_map, M_CTL);
 	port->lun_map = NULL;
 	if (port->status & CTL_PORT_STATUS_ONLINE) {
@@ -3492,6 +3506,8 @@ ctl_lun_map_set(struct ctl_port *port, uint32_t plun, uint32_t glun)
 		if (status != 0)
 			return (status);
 	}
+	if (plun >= port->lun_map_size)
+		return (EINVAL);
 	old = port->lun_map[plun];
 	port->lun_map[plun] = glun;
 	if ((port->status & CTL_PORT_STATUS_ONLINE) && old == UINT32_MAX) {
@@ -3507,7 +3523,7 @@ ctl_lun_map_unset(struct ctl_port *port, uint32_t plun)
 {
 	uint32_t old;
 
-	if (port->lun_map == NULL)
+	if (port->lun_map == NULL || plun >= port->lun_map_size)
 		return (0);
 	old = port->lun_map[plun];
 	port->lun_map[plun] = UINT32_MAX;
@@ -3525,8 +3541,10 @@ ctl_lun_map_from_port(struct ctl_port *port, uint32_t lun_id)
 
 	if (port == NULL)
 		return (UINT32_MAX);
-	if (port->lun_map == NULL || lun_id == UINT32_MAX)
+	if (port->lun_map == NULL)
 		return (lun_id);
+	if (lun_id > port->lun_map_size)
+		return (UINT32_MAX);
 	return (port->lun_map[lun_id]);
 }
 
@@ -3539,7 +3557,7 @@ ctl_lun_map_to_port(struct ctl_port *port, uint32_t lun_id)
 		return (UINT32_MAX);
 	if (port->lun_map == NULL)
 		return (lun_id);
-	for (i = 0; i < CTL_MAX_LUNS; i++) {
+	for (i = 0; i < port->lun_map_size; i++) {
 		if (port->lun_map[i] == lun_id)
 			return (i);
 	}
@@ -9048,9 +9066,8 @@ ctl_report_luns(struct ctl_scsiio *ctsio)
 	struct scsi_report_luns_data *lun_data;
 	struct ctl_lun *lun, *request_lun;
 	struct ctl_port *port;
-	int num_luns, retval;
+	int num_filled, num_luns, num_port_luns, retval;
 	uint32_t alloc_len, lun_datalen;
-	int num_filled;
 	uint32_t initidx, targ_lun_id, lun_id;
 
 	retval = CTL_RETVAL_COMPLETE;
@@ -9060,9 +9077,10 @@ ctl_report_luns(struct ctl_scsiio *ctsio)
 
 	CTL_DEBUG_PRINT(("ctl_report_luns\n"));
 
-	mtx_lock(&softc->ctl_lock);
 	num_luns = 0;
-	for (targ_lun_id = 0; targ_lun_id < CTL_MAX_LUNS; targ_lun_id++) {
+	num_port_luns = port->lun_map ? port->lun_map_size : CTL_MAX_LUNS;
+	mtx_lock(&softc->ctl_lock);
+	for (targ_lun_id = 0; targ_lun_id < num_port_luns; targ_lun_id++) {
 		if (ctl_lun_map_from_port(port, targ_lun_id) != UINT32_MAX)
 			num_luns++;
 	}
@@ -9121,7 +9139,9 @@ ctl_report_luns(struct ctl_scsiio *ctsio)
 	initidx = ctl_get_initindex(&ctsio->io_hdr.nexus);
 
 	mtx_lock(&softc->ctl_lock);
-	for (targ_lun_id = 0, num_filled = 0; targ_lun_id < CTL_MAX_LUNS && num_filled < num_luns; targ_lun_id++) {
+	for (targ_lun_id = 0, num_filled = 0;
+	    targ_lun_id < num_port_luns && num_filled < num_luns;
+	    targ_lun_id++) {
 		lun_id = ctl_lun_map_from_port(port, targ_lun_id);
 		if (lun_id == UINT32_MAX)
 			continue;
diff --git a/sys/cam/ctl/ctl_frontend.c b/sys/cam/ctl/ctl_frontend.c
index 5c6fa05b6f3009..97f4e0ba44b4b1 100644
--- a/sys/cam/ctl/ctl_frontend.c
+++ b/sys/cam/ctl/ctl_frontend.c
@@ -315,7 +315,7 @@ ctl_port_online(struct ctl_port *port)
 
 	if (port->lun_enable != NULL) {
 		if (port->lun_map) {
-			for (l = 0; l < CTL_MAX_LUNS; l++) {
+			for (l = 0; l < port->lun_map_size; l++) {
 				if (ctl_lun_map_from_port(port, l) ==
 				    UINT32_MAX)
 					continue;
@@ -359,7 +359,7 @@ ctl_port_offline(struct ctl_port *port)
 		port->port_offline(port->onoff_arg);
 	if (port->lun_disable != NULL) {
 		if (port->lun_map) {
-			for (l = 0; l < CTL_MAX_LUNS; l++) {
+			for (l = 0; l < port->lun_map_size; l++) {
 				if (ctl_lun_map_from_port(port, l) ==
 				    UINT32_MAX)
 					continue;
diff --git a/sys/cam/ctl/ctl_frontend.h b/sys/cam/ctl/ctl_frontend.h
index 1dd970aa2485d2..3e42ac362edc68 100644
--- a/sys/cam/ctl/ctl_frontend.h
+++ b/sys/cam/ctl/ctl_frontend.h
@@ -225,6 +225,7 @@ struct ctl_port {
 	void		*onoff_arg;		/* passed to CTL */
 	lun_func_t	lun_enable;		/* passed to CTL */
 	lun_func_t	lun_disable;		/* passed to CTL */
+	int		lun_map_size;		/* passed to CTL */
 	uint32_t	*lun_map;		/* passed to CTL */
 	void		*targ_lun_arg;		/* passed to CTL */
 	void		(*fe_datamove)(union ctl_io *io); /* passed to CTL */
diff --git a/sys/cam/ctl/ctl_io.h b/sys/cam/ctl/ctl_io.h
index bad030f4fd1076..77f4fc9bcf6965 100644
--- a/sys/cam/ctl/ctl_io.h
+++ b/sys/cam/ctl/ctl_io.h
@@ -365,7 +365,7 @@ struct ctl_taskio {
 /*
  * HA link messages.
  */
-#define	CTL_HA_VERSION		1
+#define	CTL_HA_VERSION		2
 
 /*
  * Used for CTL_MSG_LOGIN.