[PATCH 1/1] nvmet: allow setting model_number once

[Chaitanya Kulkarni]

Max,

On 2/17/21 10:12, Max Gurtovoy wrote:
> 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 NVM
> 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."
We don't support persistent event log page since there is no use
case for target to have human readable format with timestamps,
instead we do maintain the error log page which has information
about the errors if user wants.

I'll let Christoph/Sagi decide if we really need to implement
Persistent Event (PE) log and so does this behavior.

Regarding preventing from changing the model_number when subsys is
connected to the host, that needs a fix and I sent a patch for that.

We can ignore that patch if we decide to go with this patch with
PR log page.

> 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.