[systemd-devel] tentative state and unmount on mapper

Lennart Poettering mzerqung at 0pointer.de
Tue May 19 03:59:48 PDT 2015

On Tue, 19.05.15 12:43, Martin Pitt (martin.pitt at ubuntu.com) wrote:

> Lennart Poettering [2015-05-19 12:28 +0200]:
> > > Note that it's a permanent state in containers where you don't
> > > actually have udev.
> > 
> > NO! 
> > 
> > Martin, as mentioned earlier: current systemd will not bother with
> > device units at all in containers, and they hence will not be in
> > "tentative" state either.
> Ok ok :) -- FTR, I can't personally stop people from misconfiguring their
> containers to have writable /sys, I'm just the messenger here.
> But we've seen that there are other situations where exactly the same
> situation applies (plan9 in VM, device mapper, etc.): I. e. we have a
> real-iron machine or VM (writable /sys) with devices which aren't in
> /dev, and thus end up being tentative. Making a container with
> writable /sys is just a convenient way to reproduce/test this, I'm not
> saying it's an actual use case we need to optimize for.
> So please consider my previous reply to replace "container" with
> "situations with a mounted device not being in /dev".

Again, devices should stay in "tentative" state only very shortly. If
your device stays in "tentative" state continously after boot, then
that's something to fix in your device layer. i.e. the plan9 or device
mapper devices need to be fixed so that they show up propery in udev. 

Yes, we shouldn't unmount "tentative" devices prematurely, since the
time windows exists, but to say this clearly: if you device stays in
that state for a long time then that's indication that there's
something wrong with your device setup, and not with systemd... You
are probably missing udev rules that mark your devices as ready for
systemd to pick it up. And you should fix *that*, and not rely on
systemd not being too agressive with "tentative" devices.


Lennart Poettering, Red Hat

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