nvmet: model_number must be immutable once set

In case we have already established connection to nvmf target, it
shouldn't be allowed to change the model_number. E.g. if someone will
identify ctrl and get model_number of "my_model" later on will change
the model_numbel via configfs to "my_new_model" this will break the NVMe
specification for "Get Log Page – Persistent Event Log" that refers to
Model Number as: "This field contains the same value as reported in the
Model Number field of the Identify Controller data structure, bytes
63:24."

Although it doesn't mentioned explicitly that this field can't be
changed, we can assume it.

So allow setting this field only once: using configfs or in the first
identify ctrl operation.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 1 insertions, 6 deletions

diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index cdfa537b1c0a..4b84edb49f22 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -208,11 +208,6 @@ struct nvmet_ctrl {
 	bool			pi_support;
 };
 
-struct nvmet_subsys_model {
-	struct rcu_head		rcuhead;
-	char			number[];
-};
-
 struct nvmet_subsys {
 	enum nvme_subsys_type	type;
 
@@ -242,7 +237,7 @@ struct nvmet_subsys {
 	struct config_group	namespaces_group;
 	struct config_group	allowed_hosts_group;
 
-	struct nvmet_subsys_model	__rcu *model;
+	char			*model_number;
 
 #ifdef CONFIG_NVME_TARGET_PASSTHRU
 	struct nvme_ctrl	*passthru_ctrl;