live filesystem. To obtain a consistent dump image, dump takes
a snapshot of the filesystem and then does a dump of the snapshot.
The snapshot is removed when the dump is complete.
Also add an operator warning that the `L' option should be used
if dump is run on a live filesystem without the `L' option being
specified. The alternative would be to silently use a snapshot
any time that a live filesystem is dumped, but this change in
dump semantics seemed too drastic at this time.
Sponsored by: DARPA & NAI Labs.
Approved by: re
194a666749