iscsi-target: Add tpg_enabled_sendtargets for disabled discovery

This patch adds a new tpg_enabled_sendtargets configfs attribute
to allow in-band sendtargets discovery information to include
target-portal-groups (TPGs) in !TPG_STATE_ACTIVE state.

This functionality is useful for clustered iSCSI targets, where
TPGTs handled on remote cluster nodes should be advertised in
the SendTargets response.

By default, this new attribute retains the default behaviour of
existing code which to ignore portal-groups in !TPG_STATE_ACTIVE
state.
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -3398,6 +3398,7 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
 	int target_name_printed;
 	unsigned char buf[ISCSI_IQN_LEN+12]; /* iqn + "TargetName=" + \0 */
 	unsigned char *text_in = cmd->text_in_ptr, *text_ptr = NULL;
+	bool active;
 
 	buffer_len = min(conn->conn_ops->MaxRecvDataSegmentLength,
 			 SENDTARGETS_BUF_LIMIT);
@@ -3451,13 +3452,12 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
 			}
 
 			spin_lock(&tpg->tpg_state_lock);
-			if ((tpg->tpg_state == TPG_STATE_FREE) ||
-			    (tpg->tpg_state == TPG_STATE_INACTIVE)) {
-				spin_unlock(&tpg->tpg_state_lock);
-				continue;
-			}
+			active = (tpg->tpg_state == TPG_STATE_ACTIVE);
 			spin_unlock(&tpg->tpg_state_lock);
 
+			if (!active && tpg->tpg_attrib.tpg_enabled_sendtargets)
+				continue;
+
 			spin_lock(&tpg->tpg_np_lock);
 			list_for_each_entry(tpg_np, &tpg->tpg_gnp_list,
 						tpg_np_list) {

drivers/target/iscsi/iscsi_target_configfs.c

@@ -1010,6 +1010,11 @@ TPG_ATTR(t10_pi, S_IRUGO | S_IWUSR);
  */
 DEF_TPG_ATTRIB(fabric_prot_type);
 TPG_ATTR(fabric_prot_type, S_IRUGO | S_IWUSR);
+/*
+ * Define iscsi_tpg_attrib_s_tpg_enabled_sendtargets
+ */
+DEF_TPG_ATTRIB(tpg_enabled_sendtargets);
+TPG_ATTR(tpg_enabled_sendtargets, S_IRUGO | S_IWUSR);
 
 static struct configfs_attribute *lio_target_tpg_attrib_attrs[] = {
 	&iscsi_tpg_attrib_authentication.attr,
@@ -1024,6 +1029,7 @@ static struct configfs_attribute *lio_target_tpg_attrib_attrs[] = {
 	&iscsi_tpg_attrib_default_erl.attr,
 	&iscsi_tpg_attrib_t10_pi.attr,
 	&iscsi_tpg_attrib_fabric_prot_type.attr,
+	&iscsi_tpg_attrib_tpg_enabled_sendtargets.attr,
 	NULL,
 };
 

drivers/target/iscsi/iscsi_target_tpg.c

@@ -226,6 +226,7 @@ static void iscsit_set_default_tpg_attribs(struct iscsi_portal_group *tpg)
 	a->default_erl = TA_DEFAULT_ERL;
 	a->t10_pi = TA_DEFAULT_T10_PI;
 	a->fabric_prot_type = TA_DEFAULT_FABRIC_PROT_TYPE;
+	a->tpg_enabled_sendtargets = TA_DEFAULT_TPG_ENABLED_SENDTARGETS;
 }
 
 int iscsit_tpg_add_portal_group(struct iscsi_tiqn *tiqn, struct iscsi_portal_group *tpg)
@@ -892,3 +893,21 @@ int iscsit_ta_fabric_prot_type(
 
 	return 0;
 }
+
+int iscsit_ta_tpg_enabled_sendtargets(
+	struct iscsi_portal_group *tpg,
+	u32 flag)
+{
+	struct iscsi_tpg_attrib *a = &tpg->tpg_attrib;
+
+	if ((flag != 0) && (flag != 1)) {
+		pr_err("Illegal value %d\n", flag);
+		return -EINVAL;
+	}
+
+	a->tpg_enabled_sendtargets = flag;
+	pr_debug("iSCSI_TPG[%hu] - TPG enabled bit required for SendTargets:"
+		" %s\n", tpg->tpgt, (a->tpg_enabled_sendtargets) ? "ON" : "OFF");
+
+	return 0;
+}

drivers/target/iscsi/iscsi_target_tpg.h

@@ -40,5 +40,6 @@ extern int iscsit_ta_demo_mode_discovery(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_default_erl(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_t10_pi(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_fabric_prot_type(struct iscsi_portal_group *, u32);
+extern int iscsit_ta_tpg_enabled_sendtargets(struct iscsi_portal_group *, u32);
 
 #endif /* ISCSI_TARGET_TPG_H */

include/target/iscsi/iscsi_target_core.h

@@ -62,6 +62,8 @@
 /* T10 protection information disabled by default */
 #define TA_DEFAULT_T10_PI		0
 #define TA_DEFAULT_FABRIC_PROT_TYPE	0
+/* TPG status needs to be enabled to return sendtargets discovery endpoint info */
+#define TA_DEFAULT_TPG_ENABLED_SENDTARGETS 1
 
 #define ISCSI_IOV_DATA_BUFFER		5
 
@@ -763,6 +765,7 @@ struct iscsi_tpg_attrib {
 	u32			default_erl;
 	u8			t10_pi;
 	u32			fabric_prot_type;
+	u32			tpg_enabled_sendtargets;
 	struct iscsi_portal_group *tpg;
 };