ocfs2: wait for recovering done after direct unlock request

There is a scenario causing ocfs2 umount hang when multiple hosts are
rebooting at the same time.

NODE1                           NODE2               NODE3
send unlock requset to NODE2
                                dies
                                                    become recovery master
                                                    recover NODE2
find NODE2 dead
mark resource RECOVERING
directly remove lock from grant list
calculate usage but RECOVERING marked
**miss the window of purging
clear RECOVERING

To reproduce this issue, crash a host and then umount ocfs2
from another node.

To solve this, just let unlock progress wait for recovery done.

Link: http://lkml.kernel.org/r/1550124866-20367-1-git-send-email-gechangwei@live.cn
Signed-off-by: Changwei Ge <gechangwei@live.cn>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>