[Bug 1554031] Re: error: internal error: unable to execute QEMU command ‘block-commit’: Could not reopen file: Permission denied

[Serge Hallyn]

strace shows:

5082
open("/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZDpzZXJ2ZXI6MTYuMDQ6YW1kNjQgMjAxNjAxMjU=",
O_RDWR|O_CLOEXEC) = -1 EACCES (Permission denied)

The apparmor profile (libvirt-uuid.files) includes:

  "/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZDpzZXJ2ZXI6MTYuMDQ6YW1kNjQgMjAxNjAxMjU=" r,
  # don't audit writes to readonly files
  deny "/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZDpzZXJ2ZXI6MTYuMDQ6YW1kNjQgMjAxNjAxMjU=" w,
  "/var/lib/uvtool/libvirt/images/docker-ds.qcow" rw,
  /dev/vhost-net rw,
  "/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZDpzZXJ2ZXI6MTYuMDQ6YW1kNjQgMjAxNjAxMjU=" rw,

That long filename is the (readonly) backing file for the root disk.

sudo qemu-img info docker.qcow
image: docker.qcow
file format: qcow2
virtual size: 30G (32212254720 bytes)
disk size: 7.0G
cluster_size: 65536
backing file: /var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZDpzZXJ2ZXI6MTYuMDQ6YW1kNjQgMjAxNjAxMjU=
backing file format: qcow2
Format specific information:
    compat: 0.10
    refcount bits: 16

So it would seem we could consider this (a) a bug in qemu for requiring
write access to a readonly backing file, or (b) a bug in libvirt for
denying that write access.

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https://bugs.launchpad.net/bugs/1554031

Title:
  error: internal error: unable to execute QEMU command ‘block-commit’:
  Could not reopen file: Permission denied

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