Ceph » rbd

There is a potential race between disabling the exclusive-lock feature from the rbd CLI and a another process with in-fligth IO attempting to re-acquire the now non-existent exclusive lock:

2016-06-13 09:47:29.342043 7fe0d6ffd700 10 librbd::ExclusiveLock: 0x7fe0bc004aa0 handle_lock_released
2016-06-13 09:47:29.342043 7fe0d6ffd700 10 librbd::ExclusiveLock: 0x7fe0bc004aa0 send_acquire_lock
2016-06-13 09:47:29.342046 7fe0d6ffd700 10 librbd::exclusive_lock::AcquireRequest: send_flush_notifies
2016-06-13 09:47:29.342049 7fe0d6ffd700 10 librbd::exclusive_lock::AcquireRequest: handle_flush_notifies
2016-06-13 09:47:29.342050 7fe0d6ffd700 10 librbd::exclusive_lock::AcquireRequest: send_lock
2016-06-13 09:47:29.344031 7fe0d77fe700 10 librbd::exclusive_lock::AcquireRequest: handle_lock: r=0
2016-06-13 09:47:29.344036 7fe0d77fe700 10 librbd::exclusive_lock::AcquireRequest: send_refresh
2016-06-13 09:47:29.344037 7fe0d77fe700 20 librbd::ImageState: refresh
2016-06-13 09:47:29.344038 7fe0d77fe700 10 librbd::ImageState: 0x55e7331c0e00 send_refresh_unlock
2016-06-13 09:47:29.344040 7fe0d77fe700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 send_v2_get_mutable_metadata
2016-06-13 09:47:29.345058 7fe0d77fe700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 handle_v2_get_mutable_metadata: r=0
2016-06-13 09:47:29.345067 7fe0d77fe700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 send_v2_get_flags
2016-06-13 09:47:29.345959 7fe0d77fe700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 handle_v2_get_flags: r=0
2016-06-13 09:47:29.345966 7fe0d77fe700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 send_v2_apply
2016-06-13 09:47:29.345984 7fe0d6ffd700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 handle_v2_apply
2016-06-13 09:47:29.345989 7fe0d6ffd700 20 librbd::image::RefreshRequest: 0x7fe0bc0008c0 apply
2016-06-13 09:47:29.345993 7fe0d6ffd700 10 librbd::image::RefreshRequest: 0x7fe0bc0008c0 send_v2_shut_down_exclusive_lock
2016-06-13 09:47:29.345994 7fe0d6ffd700 10 librbd::ExclusiveLock: 0x7fe0bc004aa0 shut_down

In this case, the attempt to shut down the exclusive lock will be stalled behind the attempt to acquire the exclusive lock.