Since the copygc thread is now global and not per device, we're not
freeing up space on any one device in bounded time - and indeed we never
really were, since rebalance wasn't moving data around between devices
with that objective.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>