[PATCH 2/2] nvmet: Add port transport active flag

[Max Gurtovoy]

On 3/20/2018 1:30 PM, Sagi Grimberg wrote:
> 
>>>> tractive port flag means that nvmet transport is active and ready for
>>>> receiving requests from host.
>>>> It differ from enabled port state (port with subsystem symbolic link)
>>>> which doesn't guarantee this.
>>>> The tractive flag is necessary in case the physical ports become down
>>>> while nvmet ports are enabled.
>>>> In this case the port state remains enabled but tractive flag 
>>>> becomes false.
>>>>
>>>> The tractive flag will help the administrator to monitor the port state
>>>> from transport point of view.
>>>> The commit also add the ability to activate the port by simply writing
>>>> to tractive at the configfs.
>>>> e.g.: echo 1 > config/nvmet/ports/1/tractive
>>>
>>> Why this is a write-able variable? this is a state. I would rename it
>>> to be trstate.
>>
>> We need a write-able entry to bring-up a listener in case the 
>> port/link went down.
>> Would you prefer 2 new configfs entries ? trstate (RO) and tractivate 
>> (WO) ?
> 
> No, I would prefer a trstate which is RO and activation with a subsystem
> symlink. We can easily take care of re-activation in the transport.

The initial activation is done using a subsystem symlink.
Please share your idea for re-activation (IIRC you were against 
re-activation in the kernel and prefered a user space re-activation).
We are reffering to situations where the LLD is unloaded or some other 
fatal event occur (EEH on Power systems for example)...