block: update io_ticks when io hang

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4STNX?from=project-issue
CVE: NA

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

When the inflight IOs are slow and no new IOs are issued, we expect
iostat could manifest the IO hang problem. However after
commit 5b18b5a7 ("block: delete part_round_stats and switch to less
precise counting"), io_tick and time_in_queue will not be updated until
the end of IO, and the avgqu-sz and %util columns of iostat will be zero.

Because it has using stat.nsecs accumulation to express time_in_queue
which is not suitable to change, and may %util will express the status
better when io hang occur. To fix io_ticks, we use update_io_ticks and
inflight to update io_ticks when diskstats_show and part_stat_show
been called.

Fixes: 5b18b5a7 ("block: delete part_round_stats and switch to less precise counting")
Signed-off-by: NZhang Wensheng <zhangwensheng5@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

block/blk-core.c

@@ -1249,7 +1249,7 @@ unsigned int blk_rq_err_bytes(const struct request *rq)
 }
 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
 
-static void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
 {
 	unsigned long stamp;
 again:

block/blk.h

@@ -255,6 +255,8 @@ static inline bool blk_do_io_stat(struct request *rq)
 	return rq->rq_disk && (rq->rq_flags & RQF_IO_STAT);
 }
 
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end);
+
 static inline void req_set_nomerge(struct request_queue *q, struct request *req)
 {
 	req->cmd_flags |= REQ_NOMERGE;

block/genhd.c

@@ -1301,12 +1301,17 @@ ssize_t part_stat_show(struct device *dev,
 	struct disk_stats stat;
 	unsigned int inflight;
 
-	part_stat_read_all(p, &stat);
 	if (queue_is_mq(q))
 		inflight = blk_mq_in_flight(q, p);
 	else
 		inflight = part_in_flight(p);
 
+	if (inflight) {
+		part_stat_lock();
+		update_io_ticks(p, jiffies, true);
+		part_stat_unlock();
+	}
+	part_stat_read_all(p, &stat);
 	return sprintf(buf,
 		"%8lu %8lu %8llu %8u "
 		"%8lu %8lu %8llu %8u "
@@ -1623,12 +1628,17 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 
 	disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
 	while ((hd = disk_part_iter_next(&piter))) {
-		part_stat_read_all(hd, &stat);
 		if (queue_is_mq(gp->queue))
 			inflight = blk_mq_in_flight(gp->queue, hd);
 		else
 			inflight = part_in_flight(hd);
 
+		if (inflight) {
+			part_stat_lock();
+			update_io_ticks(hd, jiffies, true);
+			part_stat_unlock();
+		}
+		part_stat_read_all(hd, &stat);
 		seq_printf(seqf, "%4d %7d %s "
 			   "%lu %lu %lu %u "
 			   "%lu %lu %lu %u "