configfs: switch ->default groups to a linked list

Replace the current NULL-terminated array of default groups with a linked
list.  This gets rid of lots of nasty code to size and/or dynamically
allocate the array.

While we're at it also provide a conveniant helper to remove the default
groups.

Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: Felipe Balbi <[email protected]>		[drivers/usb/gadget]
Acked-by: Joel Becker <[email protected]>
Acked-by: Nicholas Bellinger <[email protected]>
Reviewed-by: Sagi Grimberg <[email protected]>

Author: Christoph Hellwig

Documentation/filesystems/configfs/configfs.txt

@@ -250,7 +250,8 @@ child item.
 		struct config_item		cg_item;
 		struct list_head		cg_children;
 		struct configfs_subsystem 	*cg_subsys;
-		struct config_group		**default_groups;
+		struct list_head		default_groups;
+		struct list_head		group_entry;
 	};
 
 	void config_group_init(struct config_group *group);
@@ -420,15 +421,15 @@ These automatic subgroups, or default groups, do not preclude other
 children of the parent group.  If ct_group_ops->make_group() exists,
 other child groups can be created on the parent group directly.
 
-A configfs subsystem specifies default groups by filling in the
-NULL-terminated array default_groups on the config_group structure.
-Each group in that array is populated in the configfs tree at the same
+A configfs subsystem specifies default groups by adding them using the
+configfs_add_default_group() function to the parent config_group
+structure.  Each added group is populated in the configfs tree at the same
 time as the parent group.  Similarly, they are removed at the same time
 as the parent.  No extra notification is provided.  When a ->drop_item()
 method call notifies the subsystem the parent group is going away, it
 also means every default group child associated with that parent group.
 
-As a consequence of this, default_groups cannot be removed directly via
+As a consequence of this, default groups cannot be removed directly via
 rmdir(2).  They also are not considered when rmdir(2) on the parent
 group is checking for children.
 

drivers/infiniband/core/cma_configfs.c

@@ -49,8 +49,6 @@ struct cma_dev_group {
 	char				name[IB_DEVICE_NAME_MAX];
 	struct config_group		device_group;
 	struct config_group		ports_group;
-	struct config_group		*default_dev_group[2];
-	struct config_group		**default_ports_group;
 	struct cma_dev_port_group	*ports;
 };
 
@@ -158,7 +156,6 @@ static int make_cma_ports(struct cma_dev_group *cma_dev_group,
 	unsigned int i;
 	unsigned int ports_num;
 	struct cma_dev_port_group *ports;
-	struct config_group **ports_group;
 	int err;
 
 	ibdev = cma_get_ib_dev(cma_dev);
@@ -169,9 +166,8 @@ static int make_cma_ports(struct cma_dev_group *cma_dev_group,
 	ports_num = ibdev->phys_port_cnt;
 	ports = kcalloc(ports_num, sizeof(*cma_dev_group->ports),
 			GFP_KERNEL);
-	ports_group = kcalloc(ports_num + 1, sizeof(*ports_group), GFP_KERNEL);
 
-	if (!ports || !ports_group) {
+	if (!ports) {
 		err = -ENOMEM;
 		goto free;
 	}
@@ -185,18 +181,16 @@ static int make_cma_ports(struct cma_dev_group *cma_dev_group,
 		config_group_init_type_name(&ports[i].group,
 					    port_str,
 					    &cma_port_group_type);
-		ports_group[i] = &ports[i].group;
+		configfs_add_default_group(&ports[i].group,
+				&cma_dev_group->ports_group);
+
 	}
-	ports_group[i] = NULL;
-	cma_dev_group->default_ports_group = ports_group;
 	cma_dev_group->ports = ports;
 
 	return 0;
 free:
 	kfree(ports);
-	kfree(ports_group);
 	cma_dev_group->ports = NULL;
-	cma_dev_group->default_ports_group = NULL;
 	return err;
 }
 
@@ -220,9 +214,7 @@ static void release_cma_ports_group(struct config_item  *item)
 							   ports_group);
 
 	kfree(cma_dev_group->ports);
-	kfree(cma_dev_group->default_ports_group);
 	cma_dev_group->ports = NULL;
-	cma_dev_group->default_ports_group = NULL;
 };
 
 static struct configfs_item_operations cma_ports_item_ops = {
@@ -263,22 +255,17 @@ static struct config_group *make_cma_dev(struct config_group *group,
 
 	strncpy(cma_dev_group->name, name, sizeof(cma_dev_group->name));
 
-	err = make_cma_ports(cma_dev_group, cma_dev);
-	if (err)
-		goto fail;
-
-	cma_dev_group->ports_group.default_groups =
-		cma_dev_group->default_ports_group;
 	config_group_init_type_name(&cma_dev_group->ports_group, "ports",
 				    &cma_ports_group_type);
 
-	cma_dev_group->device_group.default_groups
-		= cma_dev_group->default_dev_group;
-	cma_dev_group->default_dev_group[0] = &cma_dev_group->ports_group;
-	cma_dev_group->default_dev_group[1] = NULL;
+	err = make_cma_ports(cma_dev_group, cma_dev);
+	if (err)
+		goto fail;
 
 	config_group_init_type_name(&cma_dev_group->device_group, name,
 				    &cma_device_group_type);
+	configfs_add_default_group(&cma_dev_group->ports_group,
+			&cma_dev_group->device_group);
 
 	cma_deref_dev(cma_dev);
 	return &cma_dev_group->device_group;

drivers/target/iscsi/iscsi_target_configfs.c

@@ -771,39 +771,20 @@ static int lio_target_init_nodeacl(struct se_node_acl *se_nacl,
 {
 	struct iscsi_node_acl *acl =
 		container_of(se_nacl, struct iscsi_node_acl, se_node_acl);
-	struct config_group *stats_cg = &se_nacl->acl_fabric_stat_group;
-
-	stats_cg->default_groups = kmalloc(sizeof(struct config_group *) * 2,
-				GFP_KERNEL);
-	if (!stats_cg->default_groups) {
-		pr_err("Unable to allocate memory for"
-				" stats_cg->default_groups\n");
-		return -ENOMEM;
-	}
 
-	stats_cg->default_groups[0] = &acl->node_stat_grps.iscsi_sess_stats_group;
-	stats_cg->default_groups[1] = NULL;
 	config_group_init_type_name(&acl->node_stat_grps.iscsi_sess_stats_group,
 			"iscsi_sess_stats", &iscsi_stat_sess_cit);
-
+	configfs_add_default_group(&acl->node_stat_grps.iscsi_sess_stats_group,
+			&se_nacl->acl_fabric_stat_group);
 	return 0;
 }
 
 static void lio_target_cleanup_nodeacl( struct se_node_acl *se_nacl)
 {
 	struct iscsi_node_acl *acl = container_of(se_nacl,
 			struct iscsi_node_acl, se_node_acl);
-	struct config_item *df_item;
-	struct config_group *stats_cg;
-	int i;
-
-	stats_cg = &acl->se_node_acl.acl_fabric_stat_group;
-	for (i = 0; stats_cg->default_groups[i]; i++) {
-		df_item = &stats_cg->default_groups[i]->cg_item;
-		stats_cg->default_groups[i] = NULL;
-		config_item_put(df_item);
-	}
-	kfree(stats_cg->default_groups);
+
+	configfs_remove_default_groups(&acl->se_node_acl.acl_fabric_stat_group);
 }
 
 /* End items for lio_target_acl_cit */
@@ -1260,42 +1241,37 @@ static struct se_wwn *lio_target_call_coreaddtiqn(
 	struct config_group *group,
 	const char *name)
 {
-	struct config_group *stats_cg;
 	struct iscsi_tiqn *tiqn;
 
 	tiqn = iscsit_add_tiqn((unsigned char *)name);
 	if (IS_ERR(tiqn))
 		return ERR_CAST(tiqn);
-	/*
-	 * Setup struct iscsi_wwn_stat_grps for se_wwn->fabric_stat_group.
-	 */
-	stats_cg = &tiqn->tiqn_wwn.fabric_stat_group;
-
-	stats_cg->default_groups = kmalloc(sizeof(struct config_group *) * 6,
-				GFP_KERNEL);
-	if (!stats_cg->default_groups) {
-		pr_err("Unable to allocate memory for"
-				" stats_cg->default_groups\n");
-		iscsit_del_tiqn(tiqn);
-		return ERR_PTR(-ENOMEM);
-	}
 
-	stats_cg->default_groups[0] = &tiqn->tiqn_stat_grps.iscsi_instance_group;
-	stats_cg->default_groups[1] = &tiqn->tiqn_stat_grps.iscsi_sess_err_group;
-	stats_cg->default_groups[2] = &tiqn->tiqn_stat_grps.iscsi_tgt_attr_group;
-	stats_cg->default_groups[3] = &tiqn->tiqn_stat_grps.iscsi_login_stats_group;
-	stats_cg->default_groups[4] = &tiqn->tiqn_stat_grps.iscsi_logout_stats_group;
-	stats_cg->default_groups[5] = NULL;
 	config_group_init_type_name(&tiqn->tiqn_stat_grps.iscsi_instance_group,
 			"iscsi_instance", &iscsi_stat_instance_cit);
+	configfs_add_default_group(&tiqn->tiqn_stat_grps.iscsi_instance_group,
+			&tiqn->tiqn_wwn.fabric_stat_group);
+
 	config_group_init_type_name(&tiqn->tiqn_stat_grps.iscsi_sess_err_group,
 			"iscsi_sess_err", &iscsi_stat_sess_err_cit);
+	configfs_add_default_group(&tiqn->tiqn_stat_grps.iscsi_sess_err_group,
+			&tiqn->tiqn_wwn.fabric_stat_group);
+
 	config_group_init_type_name(&tiqn->tiqn_stat_grps.iscsi_tgt_attr_group,
 			"iscsi_tgt_attr", &iscsi_stat_tgt_attr_cit);
+	configfs_add_default_group(&tiqn->tiqn_stat_grps.iscsi_tgt_attr_group,
+			&tiqn->tiqn_wwn.fabric_stat_group);
+
 	config_group_init_type_name(&tiqn->tiqn_stat_grps.iscsi_login_stats_group,
 			"iscsi_login_stats", &iscsi_stat_login_cit);
+	configfs_add_default_group(&tiqn->tiqn_stat_grps.iscsi_login_stats_group,
+			&tiqn->tiqn_wwn.fabric_stat_group);
+
 	config_group_init_type_name(&tiqn->tiqn_stat_grps.iscsi_logout_stats_group,
 			"iscsi_logout_stats", &iscsi_stat_logout_cit);
+	configfs_add_default_group(&tiqn->tiqn_stat_grps.iscsi_logout_stats_group,
+			&tiqn->tiqn_wwn.fabric_stat_group);
+
 
 	pr_debug("LIO_Target_ConfigFS: REGISTER -> %s\n", tiqn->tiqn);
 	pr_debug("LIO_Target_ConfigFS: REGISTER -> Allocated Node:"
@@ -1307,17 +1283,8 @@ static void lio_target_call_coredeltiqn(
 	struct se_wwn *wwn)
 {
 	struct iscsi_tiqn *tiqn = container_of(wwn, struct iscsi_tiqn, tiqn_wwn);
-	struct config_item *df_item;
-	struct config_group *stats_cg;
-	int i;
-
-	stats_cg = &tiqn->tiqn_wwn.fabric_stat_group;
-	for (i = 0; stats_cg->default_groups[i]; i++) {
-		df_item = &stats_cg->default_groups[i]->cg_item;
-		stats_cg->default_groups[i] = NULL;
-		config_item_put(df_item);
-	}
-	kfree(stats_cg->default_groups);
+
+	configfs_remove_default_groups(&tiqn->tiqn_wwn.fabric_stat_group);
 
 	pr_debug("LIO_Target_ConfigFS: DEREGISTER -> %s\n",
 			tiqn->tiqn);