[Pkg-libvirt-maintainers] Bug#967111: libvirt: virsh attach-disk --mode readonly produces '"write" lock' error when same virt disk is mounted in another VM

[fabian.schulze]

Source: libvirt
Severity: normal

Dear Maintainer,

   * What led up to the situation?
     - a virtual disk was mounted in a VM with write access. The same disk was supposed to be attached
       in another VM with readonly access
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
     - "virsh attach disk <another VM> <virt disk> --mode readonly" was tried after successfully attaching this disk at
       the first VM 
   * What was the outcome of this action?
     - error: failed to attach disk
       error: internal error: unable to execute QEMU command 'device-add': Failed to get shared "write" lock
   * What outcome did you expect instead?
     - it was supposed to attach the disk successfully since "--mode readonly" was given


-- System Information:
Debian Release: 10.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-9-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.utf8, LC_CTYPE=de_DE.utf8 (charmap=UTF-8), LANGUAGE=de_DE.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled