When a user calls the volume-update API, we swap_volume in the libvirt
driver from the old volume attachment to the new volume attachment.
Currently, we're saving the domain XML with the old configuration prior
to updating the volume and upon a soft-reboot request, it results in an
error:
Instance soft reboot failed: Cannot access storage file <old path>
and falls back to a hard reboot, which is like pulling the power cord,
possibly resulting in file system inconsistencies.
This changes to saving the new, updated domain XML after the volume
swap.
Closes-Bug: #1713857
NOTE(melwitt): The assert in test_swap_volume_block_old_libvirt had to
be modified to account for the additional XMLDesc call from the bug
fix. The test_swap_volume_block_old_libvirt doesn't exist in Pike, so
that's why we didn't hit this in the master patch.
Change-Id: I166cde5ad8b00699e4ec02609f0d7b69236d855d
(cherry picked from commit 5b008c6540)
aa0e4ebd2c