rbd-mirror: fix races in snapshot-based mirroring deletion propagation

rbd-mirror: fix races in snapshot-based mirroring deletion propagation

When remote image is deleted, rbd-mirror can encounter three cases:

  1) no remote image id
  2) no remote mirror metadata
  3) MIRROR_IMAGE_STATE_DISABLING in remote mirror metadata

Commit d4c66ac5c615 ("rbd-mirror: fix issue with snapshot-based
mirroring deletion propagation") fixed case 1.  Cases 2 and 3 remained
broken because for both of them finalize_snapshot_state_builder() would
populate not only remote_mirror_peer_uuid but also remote_image_id,
thus disabling ENOLINK logic in handle_prepare_remote_image() and
handle_bootstrap().  Commit ff60aec2d9ef ("rbd-mirror: fix bootstrap
sequence while the image is removed") touched on case 3, but it made
a difference only for journal-based mirroring.

Stop calling finalize_snapshot_state_builder() on errors.  Instead,
align with journal-based mirroring by filling remote_mirror_peer_uuid
together with remote_mirror_uuid.

Fixes: https://tracker.ceph.com/issues/53963
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>