Re: [libvirt] [PATCH] qemu: Prevent disk corruption on domain shutdown

On Thu, Sep 15, 2011 at 12:07:27PM +0200, Jiri Denemark wrote: > Ever since we introduced fake reboot, we call qemuProcessKill as a > reaction to SHUTDOWN event. Unfortunately, qemu doesn't guarantee it > flushed all internal buffers before sending SHUTDOWN, in which case > killing the process forcibly may result in (virtual) disk corruption. > > By sending just SIGTERM without SIGKILL we give qemu time to to flush > all buffers and exit. Once qemu exits, we will see an EOF on monitor > connection and tear down the domain. In case qemu ignores SIGTERM or > just hangs there, the process stays running but that's not any different > from a possible hang anytime during the shutdown process so I think it's > just fine. > > Also qemu (since 0.14 until it's fixed) has a bug in SIGTERM processing > which causes it not to exit but instead send new SHUTDOWN event and keep > waiting. I think the best we can do is to ignore duplicate SHUTDOWN > events to avoid a SHUTDOWN-SIGTERM loop and leave the domain in paused > state. > --- > src/qemu/qemu_driver.c | 2 +- > src/qemu/qemu_process.c | 25 ++++++++++++++++++------- > src/qemu/qemu_process.h | 2 +- > 3 files changed, 20 insertions(+), 9 deletions(-) ACK this looks reasonable.