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, 1 deletions

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 67bbf0e3b507..be6fcdaf51a7 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1532,7 +1532,7 @@ static void nvmet_subsys_free(struct kref *ref)
 	nvmet_passthru_subsys_free(subsys);
 
 	kfree(subsys->subsysnqn);
-	kfree_rcu(subsys->model, rcuhead);
+	kfree(subsys->model_number);
 	kfree(subsys);
 }