Hi again On Thu, Sep 18, 2014 at 1:34 PM, David Herrmann <dh.herrm...@gmail.com> wrote: > I'm putting Harald and Kay on CC, as they added O_EXCL to protect > against parallel burning-sessions. Maybe they can tell you whether > that is still needed today and whether we can drop it.
So my conception of O_EXCL was kinda wrong. O_EXCL on block devices fails with EBUSY if, and only if, there's someone else also opening the device with O_EXCL. You can still open it without O_EXCL. Now, the kernel-internal mount helpers always keep O_EXCL for mounted block devices. This way, user-space can open block devices via O_EXCL and be sure no-one can mount it in parallel. For your automounter, this means you should just drop the event on EBUSY. If udev was the offender, you will get a follow-up event. If fsck was the offender, you're screwed anyway as it takes ages to complete (but fsck shouldn't be any problem for the automounter, anyway). if anyone else is the offender, you have no idea what they do, so you should just fail right away. Regarding lazy-unmount: It'd require kernel support to notice such usage in user-space. I don't plan on working on this (and nobody really cares). But if there will be a kernel-interface, we'd gladly accept patches to fix cdrom_id. Thanks David _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
