[PATCH 4.19] nvme: Assign subsys instance from first ctrl

[Keith Busch <kbusch@xxxxxxxxxx>]

commit 733e4b69d508d03c20adfdcf4bd27abc60fae9cc upstream

The namespace disk names must be unique for the lifetime of the
subsystem. This was accomplished by using their parent subsystems'
instances which were allocated independently from the controllers
connected to that subsystem. This allowed name prefixes assigned to
namespaces to match a controller from an unrelated subsystem, and has
created confusion among users examining device nodes.

Ensure a namespace's subsystem instance never clashes with a controller
instance of another subsystem by transferring the instance ownership
to the parent subsystem from the first controller discovered in that
subsystem.

Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Minwoo Im <minwoo.im@xxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
---
 drivers/nvme/host/core.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ae0b01059fc6..cab4f368ef2d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -88,7 +88,6 @@ 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);
 
@@ -2139,7 +2138,8 @@ static void nvme_init_subnqn(struct nvme_subsystem *subsys, struct nvme_ctrl *ct
 
 static void __nvme_release_subsystem(struct nvme_subsystem *subsys)
 {
-	ida_simple_remove(&nvme_subsystems_ida, subsys->instance);
+	if (subsys->instance >= 0)
+		ida_simple_remove(&nvme_instance_ida, subsys->instance);
 	kfree(subsys);
 }
 
@@ -2255,12 +2255,8 @@ 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);
@@ -2275,7 +2271,7 @@ 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);
@@ -2308,6 +2304,8 @@ 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);
 
@@ -2319,7 +2317,6 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 		return -EINVAL;
 	}
 
-	mutex_lock(&subsys->lock);
 	list_add_tail(&ctrl->subsys_entry, &subsys->ctrls);
 	mutex_unlock(&subsys->lock);
 
@@ -3545,7 +3542,9 @@ static void nvme_free_ctrl(struct device *dev)
 		container_of(dev, struct nvme_ctrl, ctrl_device);
 	struct nvme_subsystem *subsys = ctrl->subsys;
 
-	ida_simple_remove(&nvme_instance_ida, ctrl->instance);
+	if (subsys && ctrl->instance != subsys->instance)
+		ida_simple_remove(&nvme_instance_ida, ctrl->instance);
+
 	kfree(ctrl->effects);
 	nvme_mpath_uninit(ctrl);
 
@@ -3775,7 +3774,6 @@ 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);
-- 
2.21.0