block: update io_ticks when io hang

When the inflight IOs are slow and no new IOs are issued, we expect
iostat could manifest the IO hang problem. However after
commit 5b18b5a73760 ("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: 5b18b5a73760 ("block: delete part_round_stats and switch to less precise counting")
Signed-off-by: Zhang Wensheng <zhangwensheng5@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220217064247.4041435-1-zhangwensheng5@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index e351fac..54f60de 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -919,12 +919,17 @@ ssize_t part_stat_show(struct device *dev,
        struct disk_stats stat;
        unsigned int inflight;
 
-       part_stat_read_all(bdev, &stat);
        if (queue_is_mq(q))
                inflight = blk_mq_in_flight(q, bdev);
        else
                inflight = part_in_flight(bdev);
 
+       if (inflight) {
+               part_stat_lock();
+               update_io_ticks(bdev, jiffies, true);
+               part_stat_unlock();
+       }
+       part_stat_read_all(bdev, &stat);
        return sprintf(buf,
                "%8lu %8lu %8llu %8u "
                "%8lu %8lu %8llu %8u "
@@ -1184,12 +1189,17 @@ static int diskstats_show(struct seq_file *seqf, void *v)
        xa_for_each(&gp->part_tbl, idx, hd) {
                if (bdev_is_partition(hd) && !bdev_nr_sectors(hd))
                        continue;
-               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 %pg "
                           "%lu %lu %lu %u "
                           "%lu %lu %lu %u "