!139 nvme: Assign subsys instance from first ctrl

Merge Pull Request from: @babyihc 
 
This PR is to fix nvme disk names not unique for the lifetime of the subsystem.
Kernel issuse:
https://gitee.com/openeuler/kernel/issues/I5986O
 
 
Link:https://gitee.com/openeuler/kernel/pulls/139 
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com> 
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com> 

drivers/nvme/host/core.c

@@ -89,7 +89,6 @@ EXPORT_SYMBOL_GPL(nvme_reset_wq);
 struct workqueue_struct *nvme_delete_wq;
 EXPORT_SYMBOL_GPL(nvme_delete_wq);
 
-static DEFINE_IDA(nvme_subsystems_ida);
 static LIST_HEAD(nvme_subsystems);
 static DEFINE_MUTEX(nvme_subsystems_lock);
 
@@ -2350,7 +2349,8 @@ static void nvme_release_subsystem(struct device *dev)
 	struct nvme_subsystem *subsys =
 		container_of(dev, struct nvme_subsystem, dev);
 
-	ida_simple_remove(&nvme_subsystems_ida, subsys->instance);
+	if (subsys->instance >= 0)
+		ida_simple_remove(&nvme_instance_ida, subsys->instance);
 	kfree(subsys);
 }
 
@@ -2461,12 +2461,8 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 	subsys = kzalloc(sizeof(*subsys), GFP_KERNEL);
 	if (!subsys)
 		return -ENOMEM;
-	ret = ida_simple_get(&nvme_subsystems_ida, 0, 0, GFP_KERNEL);
-	if (ret < 0) {
-		kfree(subsys);
-		return ret;
-	}
-	subsys->instance = ret;
+
+	subsys->instance = -1;
 	mutex_init(&subsys->lock);
 	kref_init(&subsys->ref);
 	INIT_LIST_HEAD(&subsys->ctrls);
@@ -2481,7 +2477,7 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 	subsys->dev.class = nvme_subsys_class;
 	subsys->dev.release = nvme_release_subsystem;
 	subsys->dev.groups = nvme_subsys_attrs_groups;
-	dev_set_name(&subsys->dev, "nvme-subsys%d", subsys->instance);
+	dev_set_name(&subsys->dev, "nvme-subsys%d", ctrl->instance);
 	device_initialize(&subsys->dev);
 
 	mutex_lock(&nvme_subsystems_lock);
@@ -2514,6 +2510,8 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 		list_add_tail(&subsys->entry, &nvme_subsystems);
 	}
 
+	if (!found)
+		subsys->instance = ctrl->instance;
 	ctrl->subsys = subsys;
 	mutex_unlock(&nvme_subsystems_lock);
 
@@ -3840,7 +3838,9 @@ static void nvme_free_ctrl(struct device *dev)
 		container_of(dev, struct nvme_ctrl, ctrl_device);
 	struct nvme_subsystem *subsys = ctrl->subsys;
 
+	if (!subsys || ctrl->instance != subsys->instance)
 		ida_simple_remove(&nvme_instance_ida, ctrl->instance);
+
 	kfree(ctrl->effects);
 	nvme_mpath_uninit(ctrl);
 	__free_page(ctrl->discard_page);
@@ -4102,7 +4102,6 @@ int __init nvme_core_init(void)
 
 void nvme_core_exit(void)
 {
-	ida_destroy(&nvme_subsystems_ida);
 	class_destroy(nvme_subsys_class);
 	class_destroy(nvme_class);
 	unregister_chrdev_region(nvme_chr_devt, NVME_MINORS);