Re: [PATCH] mdadm/systemd: remove KillMode=none from service file

["Michal Koutný" <mkoutny@suse.com>]

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Hello.

On Wed, Aug 24, 2022 at 02:57:56PM +0200, Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com> wrote:
> It will be great if you can really prove that the mechanism is working. Do you
> know any project which really uses this functionality?

My knee-jerk response would be open-iscsi daemon but I know that this
one in particular works without '@', so I can't answer your query.

(But generally, it would only protect against the "global" killing upon
initrd transitions, not the killing of a single unit. That's likely what
you run into first during shutdown.)

Let me cross-post (back [1]) to systemd-devel ML.

> We need to handle dirty clean transaction. On shutdown, when umount is
> requested them filesystem could flush in flight data, and them kernel is
> waiting for mdmon to acknowledge the change in metadata[2].

So, technically, you'd want to order the mdmon service wrt .mount unit.
But that's unfortunately not known when mdmon@ starts based on a udev rule.

Therefore, I suspect removal of KillMode=none would need some version
of [2] to accomodate such device-service orderings.

Michal


[1] In-Reply-To: https://lists.freedesktop.org/archives/systemd-devel/2022-August/048201.html
[1] In-Reply-To: https://lore.kernel.org/r/20220824145756.000048f8@linux.intel.com/
[2] https://github.com/Werkov/systemd/commit/bdaa49d34e78981f3535c42ec19ac0f314135c07

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