Re: [Qemu-devel] [PATCH 00/10] qcow2: Implement image locking

[Vasiliy Tolstov]

2015-12-22 19:46 GMT+03:00 Kevin Wolf <address@hidden>:
> Enough innocent images have died because users called 'qemu-img snapshot' 
> while
> the VM was still running. Educating the users doesn't seem to be a working
> strategy, so this series adds locking to qcow2 that refuses to access the 
> image
> read-write from two processes.
>
> Eric, this will require a libvirt update to deal with qemu crashes which leave
> locked images behind. The simplest thinkable way would be to unconditionally
> override the lock in libvirt whenever the option is present. In that case,
> libvirt VMs would be protected against concurrent non-libvirt accesses, but 
> not
> the other way round. If you want more than that, libvirt would have to check
> somehow if it was its own VM that used the image and left the lock behind. I
> imagine that can't be too hard either.


This breaks ability to create disk only snapshot while vm is running.
Or i miss something?

-- 
Vasiliy Tolstov,
e-mail: address@hidden