Unlock before removal (once nodes are fully unavailable).

[piascikj]

This could be achieved through doing prune inside the lock
and having a cleanup method which actually performs the
deletions on the snapshotters which support it.

opened via imdone.io from a code comment on 5bd902b5cf by Michael Crosby

TODO Unlock before removal (once nodes are fully unavailable). id:894

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moby/vendor/github.com/containerd/containerd/metadata/snapshot.go

Lines 659 to 667 in 94b8a11

	// TODO: Unlock before removal (once nodes are fully unavailable).
	// This could be achieved through doing prune inside the lock
	// and having a cleanup method which actually performs the
	// deletions on the snapshotters which support it.
	for _, node := range roots {
	if err := s.pruneBranch(ctx, node); err != nil {
	return 0, err
	}