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SubjectRe: [PATCH v7 08/14] nvmet-core: allow one host per passthru-ctrl
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>>>> I don't understand why we don't limit a regular ctrl to single
>>>> access and we do it for the PT ctrl.
>>>>
>>>> I guess the block layer helps to sync between multiple access in
>>>> parallel but we can do it as well.
>>>>
>>>> Also, let's say you limit the access to this subsystem to 1 user,
>>>> the bdev is still accessibly for local user and also you can create
>>>> a different subsystem that will use this device (PT and non-PT ctrl).
>>>>
>>>> Sagi,
>>>>
>>>> can you explain the trouble you meant and how this limitation solve
>>>> it ?
>>>
>>> Its different to emulate the controller with all its admin
>>> commands vs. passing it through to the nvme device.. (think of format
>>> nvm)
>>>
>>>
>>>
>> we don't need to support format command for PT ctrl as we don't
>> support other commands such create_sq/cq.
>
> That is just an example, basically every command that we are not aware
> of we simply passthru to the drive without knowing the implications
> on a multi-host environment..

If we were to change the logic of nvmet_parse_passthru_admin_cmd to
have the default case do nvmet_parse_admin_cmd, and only have
the vendor-specific space opcodes do nvmet_passthru_execute_cmd
then I could not see at the moment how we can break a multi-host
export...

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