commit d34513d384487e8022f143a3a6b791e6d7f0dad6 upstream.

Inherit the iocb IOCB_HIPRI flag, and pass on REQ_HIPRI for
those kinds of requests.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
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>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>