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Date: Mon, 15 Jan 2024 16:44:29 -0500
From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: Martin Wilck <mwilck@suse.com>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>, dm-devel@lists.linux.dev,
	Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	Franck Bui <fbui@suse.com>
Subject: Re: [dm-devel] [PATCH v2 0/4] Diskseq support in device-mapper
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Date: Mon, 15 Jan 2024 16:44:29 -0500
From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: Martin Wilck <mwilck@suse.com>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>, dm-devel@lists.linux.dev,
	Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	Franck Bui <fbui@suse.com>
Subject: Re: [dm-devel] [PATCH v2 0/4] Diskseq support in device-mapper

On Mon, Jan 15, 2024 at 06:56:16PM +0100, Martin Wilck wrote:
> On Sat, 2023-06-24 at 19:09 -0400, Demi Marie Obenour wrote:
> > This work aims to allow userspace to create and destroy device-mapper
> > devices in a race-free way.
>=20
> The discussion about this feature seems to have stalled ... will there
> be a v3 of this series any time soon?

I=E2=80=99m still interested in a v3, but it might take a while.  If you are
willing and able to do it first, I recommend that you do so.

> Also, I am wondering what should happen if a device-mapper table is
> changed in a SUSPEND/LOAD/RESUME cycle. Such operations can change the
> content of the device, thus I assume that the diskseq should also
> change. But AFAICS this wasn't part of your patch set.
>=20
> In general, whether the content changes in a reload operation depends
> on the target. The multipath target, for example, reloads frequently
> without changing the content of the dm device. An ever-changing diskseq
> wouldn't make a lot of sense for dm-multipath. But I doubt we want to
> start making distinctions on this level, so I guess that diskseq and
> multipath just won't go well together.

Should this be controlled by userspace?
--=20
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

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