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Subject: Re: [PATCH 0/3] block: blk_interposer - Block Layer Interposer
To:     Jens Axboe <axboe@kernel.dk>, Mike Snitzer <snitzer@redhat.com>,
        Sergei Shtepa <sergei.shtepa@veeam.com>, hch@lst.de
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        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Pavel Tide <Pavel.TIde@veeam.com>, dm-devel@redhat.com
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From:   Hannes Reinecke <hare@suse.de>
Message-ID: <b4f3ee74-58fd-52c8-ae60-f352758fb42a@suse.de>
Date:   Fri, 11 Dec 2020 19:03:36 +0100
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On 12/11/20 6:04 PM, Jens Axboe wrote:
> On 12/11/20 9:56 AM, Hannes Reinecke wrote:
>> On 12/11/20 5:33 PM, Jens Axboe wrote:
>>> On 12/11/20 9:30 AM, Mike Snitzer wrote:
>>>> While I still think there needs to be a proper _upstream_ consumer of
>>>> blk_interposer as a condition of it going in.. I'll let others make the
>>>> call.
>>>
>>> That's an unequivocal rule.
>>>
>>>> As such, I'll defer to Jens, Christoph and others on whether your
>>>> minimalist blk_interposer hook is acceptable in the near-term.
>>>
>>> I don't think so, we don't do short term bandaids just to plan on
>>> ripping that out when the real functionality is there. IMHO, the dm
>>> approach is the way to go - it provides exactly the functionality that
>>> is needed in an appropriate way, instead of hacking some "interposer"
>>> into the core block layer.
>>>
>> Which is my plan, too.
>>
>> I'll be working with the Veeam folks to present a joint patchset
>> (including the DM bits) for the next round.
> 
> Just to be clear, core block additions for something that dm will
> consume is obviously fine. Adding this as block layer functionality than
> then exposes an application API for setting it up, tearing down, etc -
> that is definitely NOT
> 
That was never my intention.
Any consumers of this thing would need to be in-kernel.
If that was your concern.

Cheers,

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