[PATCH V2] nvme: report capacity 0 for non supported ZNS SSDs

[Hannes Reinecke]

On 11/2/20 7:58 PM, hch at lst.de wrote:
> On Mon, Nov 02, 2020 at 10:33:55AM -0800, Keith Busch wrote:
>> I can see this going one of two ways:
>>
>>   a) Set up the existing controller character device with a generic
>>      disk-less request_queue to the IO queues accepting IO commands to
>>      arbitrary NSIDs.
>>
>>   b) Each namespace that can't be supported gets their own character
>>      device.
>>
>> I'm leaning toward option "a". While it doesn't create handles to unique
>> namespaces, it has more resilience to potentially future changes. And I
>> recall the target side had a potential use for that, too.
> 
> The problem with a) is that it can't be used to give users or groups
> access to just one namespaces, so it causes a real access control
> nightmare.  The problem with b) is that now applications will break
> when we add support for new command sets or features.  I think
> 
>    c) Each namespace gets its own character device, period.
> 
> is the only sensible option.
> 
I hardly dare to mention bsg here; but the is pretty similar to what it 
set out to do ...

Or yet another interface?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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