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To:     Sagi Grimberg <sagi@grimberg.me>, Christoph Hellwig <hch@lst.de>
Cc:     linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
        Max Gurtovoy <maxg@mellanox.com>,
        Stephen Bates <sbates@raithlin.com>
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From:   Logan Gunthorpe <logang@deltatee.com>
Message-ID: <b8fc47a2-0b53-3316-775f-0e9a8eddfdc2@deltatee.com>
Date:   Mon, 20 Jul 2020 17:01:19 -0600
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Subject: Re: [PATCH v15 7/9] nvmet-passthru: Add passthru code to process
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On 2020-07-20 4:35 p.m., Sagi Grimberg wrote:
> 
>> Thanks for the review Christoph. I think I should be able to make all
>> the requested changes in the next week or two.
>>
>> On 2020-07-20 1:35 p.m., Sagi Grimberg wrote:
>>>
>>>> I'm still not so happy about having to look up the namespace and still
>>>> wonder if we should generalize the connect_q to a passthrough_q.  But
>>>> I guess we can do that later and then reduce some of the exports here..
>>>
>>> That is a neat idea! should be easy to do (and we can then lose the host
>>> xarray stuff). I don't mind having it on a later patch, but it should be
>>> easy enough to do even before...
>>>
>>
>> I sort of follow this. I can try to work something up but it will
>> probably take me a few iterations to get it to where you want it. So,
>> roughly, we'd create a passthrough_q in core with the controller's IO
>> tagset and then cleanup the fabrics hosts to use that instead of each
>> independently creating their connect_q?
>>
>> Though, I don't understand how this relates to the host xarray stuff
>> that Sagi mentioned...
> 
> passthru commands are in essence REQ_OP_DRV_IN/REQ_OP_DRV_OUT, which
> means that the driver shouldn't need the ns at all. So if you have a
> dedicated request queue (mapped to the I/O tagset), you don't need the
> ns->queue and we can lose the ns lookup altogether.

Thanks, that helps clarify things a bit, but which xarray were you
talking about?

Logan