[libvirt] [PATCH 0/2] Recursively lock backing chain

[Michal Privoznik]

This is how I tested the feature:

Create couple of disks:

qemu-img create -f qcow2 /var/lib/libvirt/images/test1.qcow2 1G
qemu-img create -f qcow2 /var/lib/libvirt/images/test2.qcow2 -b /var/lib/libvirt/images/test1.qcow2
qemu-img create -f qcow2 /var/lib/libvirt/images/test3.qcow2 -b /var/lib/libvirt/images/test1.qcow2

Then adjust configuration of two domains:

virsh # domblklist gentoo
Target     Source
------------------------------------------------
fda        /var/lib/libvirt/images/fd.img
vda        /var/lib/libvirt/images/gentoo.qcow2
vdb        /var/lib/libvirt/images/test1.qcow2
hdc        /home/zippy/tmp/install-amd64-minimal-20150402.iso

virsh # domblklist fedora
Target     Source
------------------------------------------------
sda        /var/lib/libvirt/images/fedora.qcow2
sdb        /var/lib/libvirt/images/test2.qcow2
hda        -


With this configuration, fedora and gentoo should not be able to run at the same time:

virsh # start fedora
Domain fedora started

virsh # start gentoo
error: Failed to start domain gentoo
error: resource busy: Lockspace resource '/var/lib/libvirt/images/test1.qcow2' is locked

Cool!

But with slight change, gentoo should be able to run:

virsh # domblklist gentoo
Target     Source
------------------------------------------------
fda        /var/lib/libvirt/images/fd.img
vda        /var/lib/libvirt/images/gentoo.qcow2
vdb        /var/lib/libvirt/images/test3.qcow2
hdc        /home/zippy/tmp/install-amd64-minimal-20150402.iso

virsh # start gentoo
Domain gentoo started

virsh # list
 Id    Name                           State
----------------------------------------------------
 10    fedora                         running
 11    gentoo                         running


Awesome!

Michal Privoznik (2):
  qemuProcessStart: Parse backingStore for all disks
  virDomainLockManagerAddImage: Recursively lock backing chain

 src/locking/domain_lock.c | 53 +++++++++++++++++++++++++++++------------------
 src/qemu/qemu_domain.c    | 11 +++-------
 src/qemu/qemu_process.c   |  6 +++++-
 3 files changed, 41 insertions(+), 29 deletions(-)

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2.4.6