[systemd-devel] [PATCH] systemd-udevd.service: restore mount propagation

[Martin Pitt]

Hey Lennart,

Lennart Poettering [2015-01-27  0:55 +0100]:
> Hmm? I don't see how mount propagation would break 60-cdrom_id... The
> eject ioctl operates on the device node, and does not care for
> mounts. This problem sounds made-up to me.

Right now cdrom_id indeed wouldn't be affected as it doesn't unmount a
CD which is about to ejected. That's the very problem that was
recently discussed here:

  http://lists.freedesktop.org/archives/systemd-devel/2015-January/026948.html

The two proposed solutions were to either teach cdrom_id --eject to
umount the device or just call the actual "eject" program which gets
this pretty much right. But neither would work because of the unshared
mount ns in udev.

> Moreover, if you want to do mounts or umounts on plug or play, then
> use a proper daemon, like udisks.

udisks actually used to have both the CD-ROM polling (which since then
moved into the kernel) and the post-eject cleanup. If we want to keep
the udev mount unsharing, we could put it back into udisks; but that
wouldn't be that robust as udisks isn't guaranteed to actually run,
both because it's a D-BUS activated service and a lot of server-ish
machines or lightweight desktops don't even have it.

Martin

-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)