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 <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 4 insertions, 7 deletions

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 60330e00f59d..fb67e313dc4f 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -1115,7 +1115,7 @@ static struct configfs_attribute *tcmu_backend_dev_attrs[] = {
 	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,
@@ -1131,11 +1131,11 @@ static struct se_subsystem_api tcmu_template = {
 	.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);
@@ -1158,10 +1158,7 @@ static int __init tcmu_module_init(void)
 		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;
 
@@ -1179,7 +1176,7 @@ out_free_cache:
 
 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);