From: Benjamin Marzinski <bmarzins@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@kernel.org>,
Bruce Johnston <bjohnsto@redhat.com>,
Matthew Sakai <msakai@redhat.com>,
dm-devel@lists.linux.dev
Subject: Re: [RFC PATCH] dm: add deviceless messages
Date: Tue, 12 May 2026 13:31:19 -0400 [thread overview]
Message-ID: <agNj5_hUfXaGQ8Nu@redhat.com> (raw)
In-Reply-To: <3bdbd9fa-52ce-ab52-569f-29d4a30c6780@redhat.com>
On Tue, May 12, 2026 at 03:36:01PM +0200, Mikulas Patocka wrote:
> The VDO code needs to perform some calculations before creating a device.
> The calculations should be performed in the kernel, so that the same logic
> is not duplicated in the kernel and in the userspace.
>
> However, currently it is not possible to call a device mapper target
> when no device exists.
>
> This commit solves the problem by adding "deviceless" messages. If the
> message starts with '%', the name is a name of a target, not a name of a
> device. The message will be directed to the target by calling the
> "deviceless_message" method. The target can perform the requested
> calculations in this method and return the result back to userspace.
>
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
next prev parent reply other threads:[~2026-05-12 17:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 13:36 [RFC PATCH] dm: add deviceless messages Mikulas Patocka
2026-05-12 13:39 ` Mikulas Patocka
2026-05-12 17:31 ` Benjamin Marzinski [this message]
2026-05-12 19:26 ` Matthew Sakai
2026-05-13 10:37 ` Mikulas Patocka
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