Old code bypass commit transaction when we don't have enough
pinned space, but another case is there exist freed bgs in current
transction, it have possibility to make alloc_chunk success.
This patch modify the condition to:
if (have_free_bg || have_pinned_space) commit_transaction()
Confirmed above action by printk before and after patch.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>