[PATCH 3/3] nvme: make SG_IO support optional

[sagig@dev.mellanox.co.il (Sagi Grimberg)]

>>> Translation SCSI commands to NVMe commands is rather pointless in general
>>> as applications must not expext to be able to use SCSI commands on a
>>> generic block device.
>>>
>>> Make the huge translation layer optional and hope no one will ever enable
>>> it in the future.
>>
>> Umm, this is needed to support multipathing (at least in the multipath
>> daemon current form). I'm not sure this is a good idea just yet...
>
> It's not required, it's just you being lazy.

I didn't say it's required, I said it's needed for the current
multipathd implementation... and yes, I am lazy, multipathd is
not the most friendly code...

> I defintivively want
> to avoid people relying on this before actual multi path hardware
> ships.  So feel free to enable it while you're lazy for now, but
> I want people to disable it normally.

OK, I see what you mean. We can look at having multipathd ioctl'ing
identify_ns at some point...