scsi: target: core: Add RTPI field to target port

SAM-5 4.6.5.2 (Relative Port Identifier attribute) defines the attribute as
unique across SCSI target ports.

The change introduces RTPI attribute to se_portal group. The value is
unique across all enabled SCSI target ports. It also limits number of SCSI
target ports to 65535.

Signed-off-by: Dmitry Bogdanov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Mike Christie <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/target_core_fabric_configfs.c

···
 
 	if (se_tpg->enabled == op)
 		return count;
-
-	ret = se_tpg->se_tpg_tfo->fabric_enable_tpg(se_tpg, op);
+	if (op)
+		ret = target_tpg_enable(se_tpg);
+	else
+		ret = target_tpg_disable(se_tpg);
 	if (ret)
 		return ret;
-
-	se_tpg->enabled = op;
-
 	return count;
 }
 

drivers/target/target_core_internal.h

···
 struct se_node_acl *core_tpg_add_initiator_node_acl(struct se_portal_group *tpg,
 		const char *initiatorname);
 void core_tpg_del_initiator_node_acl(struct se_node_acl *acl);
+int target_tpg_enable(struct se_portal_group *se_tpg);
+int target_tpg_disable(struct se_portal_group *se_tpg);
 
 /* target_core_transport.c */
 int	init_se_kmem_caches(void);

drivers/target/target_core_tpg.c

···
 #include "target_core_ua.h"
 
 extern struct se_device *g_lun0_dev;
+static DEFINE_XARRAY_ALLOC(tpg_xa);
 
 /*	__core_tpg_get_initiator_node_acl():
  *
···
 	complete(&lun->lun_shutdown_comp);
 }
 
+static int target_tpg_register_rtpi(struct se_portal_group *se_tpg)
+{
+	u32 val;
+	int ret;
+
+	ret = xa_alloc(&tpg_xa, &val, se_tpg,
+		       XA_LIMIT(1, USHRT_MAX), GFP_KERNEL);
+	if (!ret)
+		se_tpg->tpg_rtpi = val;
+
+	return ret;
+}
+
+static void target_tpg_deregister_rtpi(struct se_portal_group *se_tpg)
+{
+	if (se_tpg->tpg_rtpi && se_tpg->enabled)
+		xa_erase(&tpg_xa, se_tpg->tpg_rtpi);
+}
+
+int target_tpg_enable(struct se_portal_group *se_tpg)
+{
+	int ret;
+
+	ret = target_tpg_register_rtpi(se_tpg);
+	if (ret)
+		return ret;
+
+	ret = se_tpg->se_tpg_tfo->fabric_enable_tpg(se_tpg, true);
+	if (ret) {
+		target_tpg_deregister_rtpi(se_tpg);
+		return ret;
+	}
+
+	se_tpg->enabled = true;
+
+	return 0;
+}
+
+int target_tpg_disable(struct se_portal_group *se_tpg)
+{
+	int ret;
+
+	target_tpg_deregister_rtpi(se_tpg);
+
+	ret = se_tpg->se_tpg_tfo->fabric_enable_tpg(se_tpg, false);
+	if (!ret)
+		se_tpg->enabled = false;
+
+	return ret;
+}
+
 /* Does not change se_wwn->priv. */
 int core_tpg_register(
 	struct se_wwn *se_wwn,
···
 		core_tpg_remove_lun(se_tpg, se_tpg->tpg_virt_lun0);
 		kfree_rcu(se_tpg->tpg_virt_lun0, rcu_head);
 	}
+
+	target_tpg_deregister_rtpi(se_tpg);
 
 	return 0;
 }

include/target/target_core_base.h

···
 	 */
 	int			proto_id;
 	bool			enabled;
+	/* RELATIVE TARGET PORT IDENTIFIER */
+	u16			tpg_rtpi;
 	/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
 	atomic_t		tpg_pr_ref_count;
 	/* Spinlock for adding/removing ACLed Nodes */