block: fix sleeping function called from invalid context in part_get_stat_info()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I57S8D
CVE: NA

--------------------------------

part_get_stat_info() call mutex_lock() inside part_stat_lock(), which
is wrong because part_stat_lock() disables preempt.

Fix the problem by hold mutex first.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

block/genhd.c

@@ -1311,12 +1311,12 @@ static void part_get_stat_info(struct hd_struct *hd, struct disk_stats *stat,
 	struct request_queue *q = part_to_disk(hd)->queue;
 
 	if (queue_is_mq(q)) {
-		part_stat_lock();
 		mutex_lock(&part_to_dev(hd)->mutex);
+		part_stat_lock();
 		part_set_stat_time(hd);
 		*inflight = blk_mq_in_flight_with_stat(q, hd);
-		mutex_unlock(&part_to_dev(hd)->mutex);
 		part_stat_unlock();
+		mutex_unlock(&part_to_dev(hd)->mutex);
 	} else {
 		*inflight = part_in_flight(hd);
 	}