Merge pull request #8565 from dillaman/wip-15471

librbd: fix handling of proxied maintenance operations during shut down

Reviewed-by: Josh Durgin <jdurgin@redhat.com>

diff --cc src/librbd/ExclusiveLock.cc
Simple merge

diff --cc src/librbd/ImageWatcher.cc
Simple merge

diff --cc src/librbd/image/RefreshRequest.cc
Simple merge

diff --cc src/test/librbd/image/test_mock_RefreshRequest.cc
Simple merge