commit ba5290ccb6b57fc5e274ae46d051fba1f0ece262 upstream.

There is no function change, just to clean up the code, use s->in_async
to make the code know where it is.
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>