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Subject: Re: [PATCH 0/3] block: blk_interposer - Block Layer Interposer
To:     Bob Liu <bob.liu@oracle.com>, 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: <299962c3-c52b-a580-5b1f-a21b9021f9e6@suse.de>
Date:   Tue, 15 Dec 2020 08:41:07 +0100
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On 12/15/20 7:51 AM, Bob Liu wrote:
> Hi Folks,
> 
> On 12/12/20 12:56 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.
>>
> 
> Besides the dm approach, do you think Veeam's original requirement is a good
> use case of "block/bpf: add eBPF based block layer IO filtering"?
> https://lwn.net/ml/bpf/20200812163305.545447-1-leah.rumancik@gmail.com/
> 
That would actually a really cool use-case.
You could also consider a XDP-like functionality for eBPF, to move 
individual requests from one queue to the other; DM on steroids :-)

Should I try to include that patchset?

Cheers,

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