On Tue, 01/12 11:10, Kevin Wolf wrote: > > The problem is that libvirt already takes a lock, as Dan mentioned in > another reply in this thread, so we can't enable locking in qemu by > default. It would always fail when run under libvirt. > > Unless I'm seriously mistaken, this means that flock() inside qemu is > dead.
Yes, I see the problem with libvirt, but can we instead do these? 1) Do a soft flock() in QEMU invocation. If it fails, sliently ignore. 2) Do a hard flock() in qemu-img invocation. If it fails, report and exit. This way, if libvirt is holding flock, we can assume libvirt is actually "using" the image: 1) just works as before, but 2) will not break the qcow2. That is still a slight improvement, and does solve the reckless "qemu-img snapshot create" user's problem. Fam
