This effectively reverts the last hunk of 392a9dad7e ("rbd: detect
when clone image is flattened").
The problem with parent_overlap != 0 condition is that it's possible
and completely valid to have an image with parent_overlap == 0 whose
parent state needs to be cleaned up on unmap. The next commit, which
drops the "clone image now standalone" logic, opens up another window
of opportunity to hit this, but even without it
# cat parent-ref.sh
#!/bin/bash
rbd create --image-format 2 --size 1 foo
rbd snap create foo@snap
rbd snap protect foo@snap
rbd clone foo@snap bar
rbd resize --allow-shrink --size 0 bar
rbd resize --size 1 bar
DEV=$(rbd map bar)
rbd unmap $DEV
leaves rbd_device/rbd_spec/etc and rbd_client along with ceph_client
hanging around.
My thinking behind calling rbd_dev_parent_put() unconditionally is that
there shouldn't be any requests in flight at that point in time as we
are deep into unmap sequence. Hence, even if rbd_dev_unparent() caused
by flatten is delayed by in-flight requests, it will have finished by
the time we reach rbd_dev_unprobe() caused by unmap, thus turning
unconditional rbd_dev_parent_put() into a no-op.
Fixes: http://tracker.ceph.com/issues/10352
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
e69b8d414f