rq-qos: set ourself TASK_UNINTERRUPTIBLE after we schedule

In case we get a spurious wakeup we need to make sure to re-set
ourselves to TASK_UNINTERRUPTIBLE so we don't busy wait.
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

block/blk-rq-qos.c

@@ -262,6 +262,7 @@ void rq_qos_wait(struct rq_wait *rqw, void *private_data,
 		}
 		io_schedule();
 		has_sleeper = true;
+		set_current_state(TASK_UNINTERRUPTIBLE);
 	} while (1);
 	finish_wait(&rqw->wait, &data.wq);
 }