target: simplify backend driver registration

Rewrite the backend driver registration based on what we did to the fabric
drivers: introduce a read-only struct target_bakckend_ops that the driver
registers, which is then instanciate as a struct target_backend by the
core. This allows the ops vector to be smaller and allows us to mark it
const. At the same time the registration function can set up the
configfs attributes, avoiding the need to add additional boilerplate code
for that to the drivers.

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Nicholas Bellinger <[e-mail]>

drivers/target/target_core_configfs.c

···
 #include "target_core_xcopy.h"
 
 #define TB_CIT_SETUP(_name, _item_ops, _group_ops, _attrs)		\
-static void target_core_setup_##_name##_cit(struct se_subsystem_api *sa) \
+static void target_core_setup_##_name##_cit(struct target_backend *tb)	\
 {									\
-	struct target_backend_cits *tbc = &sa->tb_cits;			\
-	struct config_item_type *cit = &tbc->tb_##_name##_cit;		\
+	struct config_item_type *cit = &tb->tb_##_name##_cit;		\
 									\
 	cit->ct_item_ops = _item_ops;					\
 	cit->ct_group_ops = _group_ops;					\
 	cit->ct_attrs = _attrs;						\
-	cit->ct_owner = sa->owner;					\
+	cit->ct_owner = tb->ops->owner;					\
+	pr_debug("Setup generic %s\n", __stringify(_name));		\
+}
+
+#define TB_CIT_SETUP_DRV(_name, _item_ops, _group_ops)			\
+static void target_core_setup_##_name##_cit(struct target_backend *tb)	\
+{									\
+	struct config_item_type *cit = &tb->tb_##_name##_cit;		\
+									\
+	cit->ct_item_ops = _item_ops;					\
+	cit->ct_group_ops = _group_ops;					\
+	cit->ct_attrs = tb->ops->tb_##_name##_attrs;			\
+	cit->ct_owner = tb->ops->owner;					\
 	pr_debug("Setup generic %s\n", __stringify(_name));		\
 }
 
···
 	.store_attribute	= target_core_dev_attrib_attr_store,
 };
 
-TB_CIT_SETUP(dev_attrib, &target_core_dev_attrib_ops, NULL, NULL);
+TB_CIT_SETUP_DRV(dev_attrib, &target_core_dev_attrib_ops, NULL);
 
 /* End functions for struct config_item_type tb_dev_attrib_cit */
 
···
 static ssize_t target_core_show_dev_info(void *p, char *page)
 {
 	struct se_device *dev = p;
-	struct se_subsystem_api *t = dev->transport;
 	int bl = 0;
 	ssize_t read_bytes = 0;
 
 	transport_dump_dev_state(dev, page, &bl);
 	read_bytes += bl;
-	read_bytes += t->show_configfs_dev_params(dev, page+read_bytes);
+	read_bytes += dev->transport->show_configfs_dev_params(dev,
+			page+read_bytes);
 	return read_bytes;
 }
 
···
 	size_t count)
 {
 	struct se_device *dev = p;
-	struct se_subsystem_api *t = dev->transport;
 
-	return t->set_configfs_dev_params(dev, page, count);
+	return dev->transport->set_configfs_dev_params(dev, page, count);
 }
 
 static struct target_core_configfs_attribute target_core_attr_dev_control = {
···
 	const char *name)
 {
 	struct t10_alua_tg_pt_gp *tg_pt_gp;
-	struct se_subsystem_api *t;
 	struct config_item *hba_ci = &group->cg_item;
 	struct se_hba *hba = item_to_hba(hba_ci);
+	struct target_backend *tb = hba->backend;
 	struct se_device *dev;
 	struct config_group *dev_cg = NULL, *tg_pt_gp_cg = NULL;
 	struct config_group *dev_stat_grp = NULL;
···
 	ret = mutex_lock_interruptible(&hba->hba_access_mutex);
 	if (ret)
 		return ERR_PTR(ret);
-	/*
-	 * Locate the struct se_subsystem_api from parent's struct se_hba.
-	 */
-	t = hba->transport;
 
 	dev = target_alloc_device(hba, name);
 	if (!dev)
···
 	if (!dev_cg->default_groups)
 		goto out_free_device;
 
-	config_group_init_type_name(dev_cg, name, &t->tb_cits.tb_dev_cit);
+	config_group_init_type_name(dev_cg, name, &tb->tb_dev_cit);
 	config_group_init_type_name(&dev->dev_attrib.da_group, "attrib",
-			&t->tb_cits.tb_dev_attrib_cit);
+			&tb->tb_dev_attrib_cit);
 	config_group_init_type_name(&dev->dev_pr_group, "pr",
-			&t->tb_cits.tb_dev_pr_cit);
+			&tb->tb_dev_pr_cit);
 	config_group_init_type_name(&dev->t10_wwn.t10_wwn_group, "wwn",
-			&t->tb_cits.tb_dev_wwn_cit);
+			&tb->tb_dev_wwn_cit);
 	config_group_init_type_name(&dev->t10_alua.alua_tg_pt_gps_group,
-			"alua", &t->tb_cits.tb_dev_alua_tg_pt_gps_cit);
+			"alua", &tb->tb_dev_alua_tg_pt_gps_cit);
 	config_group_init_type_name(&dev->dev_stat_grps.stat_group,
-			"statistics", &t->tb_cits.tb_dev_stat_cit);
+			"statistics", &tb->tb_dev_stat_cit);
 
 	dev_cg->default_groups[0] = &dev->dev_attrib.da_group;
 	dev_cg->default_groups[1] = &dev->dev_pr_group;
···
 	char *page)
 {
 	return sprintf(page, "HBA Index: %d plugin: %s version: %s\n",
-			hba->hba_id, hba->transport->name,
+			hba->hba_id, hba->backend->ops->name,
 			TARGET_CORE_CONFIGFS_VERSION);
 }
 
···
 static ssize_t target_core_hba_store_attr_hba_mode(struct se_hba *hba,
 				const char *page, size_t count)
 {
-	struct se_subsystem_api *transport = hba->transport;
 	unsigned long mode_flag;
 	int ret;
 
-	if (transport->pmode_enable_hba == NULL)
+	if (hba->backend->ops->pmode_enable_hba == NULL)
 		return -EINVAL;
 
 	ret = kstrtoul(page, 0, &mode_flag);
···
 		return -EINVAL;
 	}
 
-	ret = transport->pmode_enable_hba(hba, mode_flag);
+	ret = hba->backend->ops->pmode_enable_hba(hba, mode_flag);
 	if (ret < 0)
 		return -EINVAL;
 	if (ret > 0)
···
 
 /* Stop functions for struct config_item_type target_core_hba_cit */
 
-void target_core_setup_sub_cits(struct se_subsystem_api *sa)
+void target_setup_backend_cits(struct target_backend *tb)
 {
-	target_core_setup_dev_cit(sa);
-	target_core_setup_dev_attrib_cit(sa);
-	target_core_setup_dev_pr_cit(sa);
-	target_core_setup_dev_wwn_cit(sa);
-	target_core_setup_dev_alua_tg_pt_gps_cit(sa);
-	target_core_setup_dev_stat_cit(sa);
+	target_core_setup_dev_cit(tb);
+	target_core_setup_dev_attrib_cit(tb);
+	target_core_setup_dev_pr_cit(tb);
+	target_core_setup_dev_wwn_cit(tb);
+	target_core_setup_dev_alua_tg_pt_gps_cit(tb);
+	target_core_setup_dev_stat_cit(tb);
 }
-EXPORT_SYMBOL(target_core_setup_sub_cits);
 
 static int __init target_core_init_configfs(void)
 {

drivers/target/target_core_device.c

···
 	struct se_device *dev;
 	struct se_lun *xcopy_lun;
 
-	dev = hba->transport->alloc_device(hba, name);
+	dev = hba->backend->ops->alloc_device(hba, name);
 	if (!dev)
 		return NULL;
 
 	dev->dev_link_magic = SE_DEV_LINK_MAGIC;
 	dev->se_hba = hba;
-	dev->transport = hba->transport;
+	dev->transport = hba->backend->ops;
 	dev->prot_length = sizeof(struct se_dif_v1_tuple);
 
 	INIT_LIST_HEAD(&dev->dev_list);
···
 		goto out_free_hba;
 	}
 
-	hba->transport->set_configfs_dev_params(dev, buf, sizeof(buf));
+	hba->backend->ops->set_configfs_dev_params(dev, buf, sizeof(buf));
 
 	ret = target_configure_device(dev);
 	if (ret)

drivers/target/target_core_file.c

···
 	return container_of(dev, struct fd_dev, dev);
 }
 
-/*	fd_attach_hba(): (Part of se_subsystem_api_t template)
- *
- *
- */
 static int fd_attach_hba(struct se_hba *hba, u32 host_id)
 {
 	struct fd_host *fd_host;
···
 	NULL,
 };
 
-static struct se_subsystem_api fileio_template = {
+static const struct target_backend_ops fileio_ops = {
 	.name			= "fileio",
 	.inquiry_prod		= "FILEIO",
 	.inquiry_rev		= FD_VERSION,
···
 	.init_prot		= fd_init_prot,
 	.format_prot		= fd_format_prot,
 	.free_prot		= fd_free_prot,
+	.tb_dev_attrib_attrs	= fileio_backend_dev_attrs,
 };
 
 static int __init fileio_module_init(void)
 {
-	struct target_backend_cits *tbc = &fileio_template.tb_cits;
-
-	target_core_setup_sub_cits(&fileio_template);
-	tbc->tb_dev_attrib_cit.ct_attrs = fileio_backend_dev_attrs;
-
-	return transport_subsystem_register(&fileio_template);
+	return transport_backend_register(&fileio_ops);
 }
 
 static void __exit fileio_module_exit(void)
 {
-	transport_subsystem_release(&fileio_template);
+	target_backend_unregister(&fileio_ops);
 }
 
 MODULE_DESCRIPTION("TCM FILEIO subsystem plugin");

drivers/target/target_core_hba.c

···
 
 #include "target_core_internal.h"
 
-static LIST_HEAD(subsystem_list);
-static DEFINE_MUTEX(subsystem_mutex);
+static LIST_HEAD(backend_list);
+static DEFINE_MUTEX(backend_mutex);
 
 static u32 hba_id_counter;
 
 static DEFINE_SPINLOCK(hba_lock);
 static LIST_HEAD(hba_list);
 
-int transport_subsystem_register(struct se_subsystem_api *sub_api)
+
+int transport_backend_register(const struct target_backend_ops *ops)
 {
-	struct se_subsystem_api *s;
+	struct target_backend *tb, *old;
 
-	INIT_LIST_HEAD(&sub_api->sub_api_list);
+	tb = kzalloc(sizeof(*tb), GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
+	tb->ops = ops;
 
-	mutex_lock(&subsystem_mutex);
-	list_for_each_entry(s, &subsystem_list, sub_api_list) {
-		if (!strcmp(s->name, sub_api->name)) {
-			pr_err("%p is already registered with"
-				" duplicate name %s, unable to process"
-				" request\n", s, s->name);
-			mutex_unlock(&subsystem_mutex);
+	mutex_lock(&backend_mutex);
+	list_for_each_entry(old, &backend_list, list) {
+		if (!strcmp(old->ops->name, ops->name)) {
+			pr_err("backend %s already registered.\n", ops->name);
+			mutex_unlock(&backend_mutex);
+			kfree(tb);
 			return -EEXIST;
 		}
 	}
-	list_add_tail(&sub_api->sub_api_list, &subsystem_list);
-	mutex_unlock(&subsystem_mutex);
+	target_setup_backend_cits(tb);
+	list_add_tail(&tb->list, &backend_list);
+	mutex_unlock(&backend_mutex);
 
-	pr_debug("TCM: Registered subsystem plugin: %s struct module:"
-			" %p\n", sub_api->name, sub_api->owner);
+	pr_debug("TCM: Registered subsystem plugin: %s struct module: %p\n",
+			ops->name, ops->owner);
 	return 0;
 }
-EXPORT_SYMBOL(transport_subsystem_register);
+EXPORT_SYMBOL(transport_backend_register);
 
-void transport_subsystem_release(struct se_subsystem_api *sub_api)
+void target_backend_unregister(const struct target_backend_ops *ops)
 {
-	mutex_lock(&subsystem_mutex);
-	list_del(&sub_api->sub_api_list);
-	mutex_unlock(&subsystem_mutex);
+	struct target_backend *tb;
+
+	mutex_lock(&backend_mutex);
+	list_for_each_entry(tb, &backend_list, list) {
+		if (tb->ops == ops) {
+			list_del(&tb->list);
+			kfree(tb);
+			break;
+		}
+	}
+	mutex_unlock(&backend_mutex);
 }
-EXPORT_SYMBOL(transport_subsystem_release);
+EXPORT_SYMBOL(target_backend_unregister);
 
-static struct se_subsystem_api *core_get_backend(const char *sub_name)
+static struct target_backend *core_get_backend(const char *name)
 {
-	struct se_subsystem_api *s;
+	struct target_backend *tb;
 
-	mutex_lock(&subsystem_mutex);
-	list_for_each_entry(s, &subsystem_list, sub_api_list) {
-		if (!strcmp(s->name, sub_name))
+	mutex_lock(&backend_mutex);
+	list_for_each_entry(tb, &backend_list, list) {
+		if (!strcmp(tb->ops->name, name))
 			goto found;
 	}
-	mutex_unlock(&subsystem_mutex);
+	mutex_unlock(&backend_mutex);
 	return NULL;
 found:
-	if (s->owner && !try_module_get(s->owner))
-		s = NULL;
-	mutex_unlock(&subsystem_mutex);
-	return s;
+	if (tb->ops->owner && !try_module_get(tb->ops->owner))
+		tb = NULL;
+	mutex_unlock(&backend_mutex);
+	return tb;
 }
 
 struct se_hba *
···
 	hba->hba_index = scsi_get_new_index(SCSI_INST_INDEX);
 	hba->hba_flags |= hba_flags;
 
-	hba->transport = core_get_backend(plugin_name);
-	if (!hba->transport) {
+	hba->backend = core_get_backend(plugin_name);
+	if (!hba->backend) {
 		ret = -EINVAL;
 		goto out_free_hba;
 	}
 
-	ret = hba->transport->attach_hba(hba, plugin_dep_id);
+	ret = hba->backend->ops->attach_hba(hba, plugin_dep_id);
 	if (ret < 0)
 		goto out_module_put;
 
···
 	return hba;
 
 out_module_put:
-	module_put(hba->transport->owner);
-	hba->transport = NULL;
+	module_put(hba->backend->ops->owner);
+	hba->backend = NULL;
 out_free_hba:
 	kfree(hba);
 	return ERR_PTR(ret);
···
 {
 	WARN_ON(hba->dev_count);
 
-	hba->transport->detach_hba(hba);
+	hba->backend->ops->detach_hba(hba);
 
 	spin_lock(&hba_lock);
 	list_del(&hba->hba_node);
···
 	pr_debug("CORE_HBA[%d] - Detached HBA from Generic Target"
 			" Core\n", hba->hba_id);
 
-	module_put(hba->transport->owner);
+	module_put(hba->backend->ops->owner);
 
-	hba->transport = NULL;
+	hba->backend = NULL;
 	kfree(hba);
 	return 0;
 }

drivers/target/target_core_iblock.c

···
 }
 
 
-static struct se_subsystem_api iblock_template;
-
-/*	iblock_attach_hba(): (Part of se_subsystem_api_t template)
- *
- *
- */
 static int iblock_attach_hba(struct se_hba *hba, u32 host_id)
 {
 	pr_debug("CORE_HBA[%d] - TCM iBlock HBA Driver %s on"
···
 	NULL,
 };
 
-static struct se_subsystem_api iblock_template = {
+static const struct target_backend_ops iblock_ops = {
 	.name			= "iblock",
 	.inquiry_prod		= "IBLOCK",
 	.inquiry_rev		= IBLOCK_VERSION,
···
 	.get_io_min		= iblock_get_io_min,
 	.get_io_opt		= iblock_get_io_opt,
 	.get_write_cache	= iblock_get_write_cache,
+	.tb_dev_attrib_attrs	= iblock_backend_dev_attrs,
 };
 
 static int __init iblock_module_init(void)
 {
-	struct target_backend_cits *tbc = &iblock_template.tb_cits;
-
-	target_core_setup_sub_cits(&iblock_template);
-	tbc->tb_dev_attrib_cit.ct_attrs = iblock_backend_dev_attrs;
-
-	return transport_subsystem_register(&iblock_template);
+	return transport_backend_register(&iblock_ops);
 }
 
 static void __exit iblock_module_exit(void)
 {
-	transport_subsystem_release(&iblock_template);
+	target_backend_unregister(&iblock_ops);
 }
 
 MODULE_DESCRIPTION("TCM IBLOCK subsystem plugin");

drivers/target/target_core_internal.h

···
 #ifndef TARGET_CORE_INTERNAL_H
 #define TARGET_CORE_INTERNAL_H
 
+struct target_backend {
+	struct list_head list;
+
+	const struct target_backend_ops *ops;
+
+	struct config_item_type tb_dev_cit;
+	struct config_item_type tb_dev_attrib_cit;
+	struct config_item_type tb_dev_pr_cit;
+	struct config_item_type tb_dev_wwn_cit;
+	struct config_item_type tb_dev_alua_tg_pt_gps_cit;
+	struct config_item_type tb_dev_stat_cit;
+};
+
 /* target_core_alua.c */
 extern struct t10_alua_lu_gp *default_lu_gp;
 
···
 struct se_device *target_alloc_device(struct se_hba *hba, const char *name);
 int	target_configure_device(struct se_device *dev);
 void	target_free_device(struct se_device *);
+
+/* target_core_configfs.c */
+void	target_setup_backend_cits(struct target_backend *);
 
 /* target_core_fabric_lib.c */
 int	target_get_pr_transport_id_len(struct se_node_acl *nacl,

drivers/target/target_core_pscsi.c

···
 	return container_of(dev, struct pscsi_dev_virt, dev);
 }
 
-static struct se_subsystem_api pscsi_template;
-
 static sense_reason_t pscsi_execute_cmd(struct se_cmd *cmd);
 static void pscsi_req_done(struct request *, int);
 
···
 	NULL,
 };
 
-static struct se_subsystem_api pscsi_template = {
+static const struct target_backend_ops pscsi_ops = {
 	.name			= "pscsi",
 	.owner			= THIS_MODULE,
 	.transport_flags	= TRANSPORT_FLAG_PASSTHROUGH,
···
 	.show_configfs_dev_params = pscsi_show_configfs_dev_params,
 	.get_device_type	= pscsi_get_device_type,
 	.get_blocks		= pscsi_get_blocks,
+	.tb_dev_attrib_attrs	= pscsi_backend_dev_attrs,
 };
 
 static int __init pscsi_module_init(void)
 {
-	struct target_backend_cits *tbc = &pscsi_template.tb_cits;
-
-	target_core_setup_sub_cits(&pscsi_template);
-	tbc->tb_dev_attrib_cit.ct_attrs = pscsi_backend_dev_attrs;
-
-	return transport_subsystem_register(&pscsi_template);
+	return transport_backend_register(&pscsi_ops);
 }
 
 static void __exit pscsi_module_exit(void)
 {
-	transport_subsystem_release(&pscsi_template);
+	target_backend_unregister(&pscsi_ops);
 }
 
 MODULE_DESCRIPTION("TCM PSCSI subsystem plugin");

drivers/target/target_core_rd.c

···
 	return container_of(dev, struct rd_dev, dev);
 }
 
-/*	rd_attach_hba(): (Part of se_subsystem_api_t template)
- *
- *
- */
 static int rd_attach_hba(struct se_hba *hba, u32 host_id)
 {
 	struct rd_host *rd_host;
···
 	NULL,
 };
 
-static struct se_subsystem_api rd_mcp_template = {
+static const struct target_backend_ops rd_mcp_ops = {
 	.name			= "rd_mcp",
 	.inquiry_prod		= "RAMDISK-MCP",
 	.inquiry_rev		= RD_MCP_VERSION,
···
 	.get_blocks		= rd_get_blocks,
 	.init_prot		= rd_init_prot,
 	.free_prot		= rd_free_prot,
+	.tb_dev_attrib_attrs	= rd_mcp_backend_dev_attrs,
 };
 
 int __init rd_module_init(void)
 {
-	struct target_backend_cits *tbc = &rd_mcp_template.tb_cits;
-	int ret;
-
-	target_core_setup_sub_cits(&rd_mcp_template);
-	tbc->tb_dev_attrib_cit.ct_attrs = rd_mcp_backend_dev_attrs;
-
-	ret = transport_subsystem_register(&rd_mcp_template);
-	if (ret < 0) {
-		return ret;
-	}
-
-	return 0;
+	return transport_backend_register(&rd_mcp_ops);
 }
 
 void rd_module_exit(void)
 {
-	transport_subsystem_release(&rd_mcp_template);
+	target_backend_unregister(&rd_mcp_ops);
 }

drivers/target/target_core_user.c

···
 	NULL,
 };
 
-static struct se_subsystem_api tcmu_template = {
+static const struct target_backend_ops tcmu_ops = {
 	.name			= "user",
 	.inquiry_prod		= "USER",
 	.inquiry_rev		= TCMU_VERSION,
···
 	.show_configfs_dev_params = tcmu_show_configfs_dev_params,
 	.get_device_type	= sbc_get_device_type,
 	.get_blocks		= tcmu_get_blocks,
+	.tb_dev_attrib_attrs	= tcmu_backend_dev_attrs,
 };
 
 static int __init tcmu_module_init(void)
 {
-	struct target_backend_cits *tbc = &tcmu_template.tb_cits;
 	int ret;
 
 	BUILD_BUG_ON((sizeof(struct tcmu_cmd_entry) % TCMU_OP_ALIGN_SIZE) != 0);
···
 		goto out_unreg_device;
 	}
 
-	target_core_setup_sub_cits(&tcmu_template);
-	tbc->tb_dev_attrib_cit.ct_attrs = tcmu_backend_dev_attrs;
-
-	ret = transport_subsystem_register(&tcmu_template);
+	ret = transport_backend_register(&tcmu_ops);
 	if (ret)
 		goto out_unreg_genl;
 
···
 
 static void __exit tcmu_module_exit(void)
 {
-	transport_subsystem_release(&tcmu_template);
+	target_backend_unregister(&tcmu_ops);
 	genl_unregister_family(&tcmu_genl_family);
 	root_device_unregister(tcmu_root_device);
 	kmem_cache_destroy(tcmu_cmd_cache);

include/target/target_core_backend.h

···
 
 #define TRANSPORT_FLAG_PASSTHROUGH		1
 
-struct target_backend_cits {
-	struct config_item_type tb_dev_cit;
-	struct config_item_type tb_dev_attrib_cit;
-	struct config_item_type tb_dev_pr_cit;
-	struct config_item_type tb_dev_wwn_cit;
-	struct config_item_type tb_dev_alua_tg_pt_gps_cit;
-	struct config_item_type tb_dev_stat_cit;
-};
-
-struct se_subsystem_api {
-	struct list_head sub_api_list;
-
+struct target_backend_ops {
 	char name[16];
 	char inquiry_prod[16];
 	char inquiry_rev[4];
···
 	int (*format_prot)(struct se_device *);
 	void (*free_prot)(struct se_device *);
 
-	struct target_backend_cits tb_cits;
+	struct configfs_attribute **tb_dev_attrib_attrs;
 };
 
 struct sbc_ops {
···
 	sense_reason_t (*execute_unmap)(struct se_cmd *cmd);
 };
 
-int	transport_subsystem_register(struct se_subsystem_api *);
-void	transport_subsystem_release(struct se_subsystem_api *);
+int	transport_backend_register(const struct target_backend_ops *);
+void	target_backend_unregister(const struct target_backend_ops *);
 
 void	target_complete_cmd(struct se_cmd *, u8);
 void	target_complete_cmd_with_length(struct se_cmd *, u8, int);
···
 		struct scatterlist *, u32, struct scatterlist *, u32);
 
 bool	target_lun_is_rdonly(struct se_cmd *);
-
-/* From target_core_configfs.c to setup default backend config_item_types */
-void	target_core_setup_sub_cits(struct se_subsystem_api *);
 
 /* attribute helpers from target_core_device.c for backend drivers */
 bool	se_dev_check_wce(struct se_device *);

include/target/target_core_base.h

···
 #define SE_UDEV_PATH_LEN 512		/* must be less than PAGE_SIZE */
 	unsigned char		udev_path[SE_UDEV_PATH_LEN];
 	/* Pointer to template of function pointers for transport */
-	struct se_subsystem_api *transport;
+	const struct target_backend_ops *transport;
 	/* Linked list for struct se_hba struct se_device list */
 	struct list_head	dev_list;
 	struct se_lun		xcopy_lun;
···
 	spinlock_t		device_lock;
 	struct config_group	hba_group;
 	struct mutex		hba_access_mutex;
-	struct se_subsystem_api *transport;
+	struct target_backend	*backend;
 };
 
 struct scsi_port_stats {