[vfio-users] Question on snapshots

[Patrick O'Callaghan]

My Windows10 VM (QEMU/KVM) had to be powered off without proper
shutdown, so its filesystem is now mangled. It won't boot and a Windows
DVD in recovery mode can't fix it. I had taken a snapshot a day earlier
so was hoping to restore from there, but this is what I get:

    $ sudo qemu-img snapshot -a /var/lib/libvirt/images/Windows10.qcow2 /home/poc/Win10/win10.qcow2 
    qemu-img: Could not apply snapshot '/var/lib/libvirt/images/Windows10.qcow2': -2 (No such file or directory)
    $ sudo qemu-img info /var/lib/libvirt/images/Windows10.qcow2
    image: /var/lib/libvirt/images/Windows10.qcow2
    file format: qcow2
    virtual size: 20G (21474836480 bytes)
    disk size: 196K
    cluster_size: 65536
    backing file: /home/poc/Win10/win10.qcow2
    backing file format: qcow2
    Format specific information:
        compat: 1.1
        lazy refcounts: true
        refcount bits: 16
        corrupt: false
    $ sudo qemu-img info win10.qcow2 
    image: win10.qcow2
    file format: qcow2
    virtual size: 100G (107374182400 bytes)
    disk size: 74G
    cluster_size: 65536
    Format specific information:
        compat: 1.1
        lazy refcounts: true
        refcount bits: 16
        corrupt: false

Clearly the files do exist and are accessible (using sudo), so the
error message is misleading.

Naturally, the crash happened after I changed the disk mode to write-
back (Murphy must have been watching), but is there anything I can do?

poc