We should have
fc0932f block: Reuse bs as backing hd for drive-backup sync=none
which fixes a latent bug in (QMP) drive-backup sync=none, that stale data might be read from the target image.
Fix included in qemu-kvm-rhev-2.9.0-6.el7
I am not sure how to verify this bz, could you help indicate it? Thanks.
No reproducer for this, please run drive-backup/blockdev-backup related regression testing.
Moving to VERIFIED per comment 5 and comment 6.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.