[PATCH 1/3] block: don't show disk stats if io accounting is disabled

[Yu Kuai]

If io accounting is disabled, there is no point to handle such device
in diskstats_show(), and it can be confused for users because all fields
in iostat are zero while the disk is handling io.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 block/genhd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index c3b32c665aec..e5307f512185 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -937,6 +937,9 @@ ssize_t part_stat_show(struct device *dev,
 	struct disk_stats stat;
 	unsigned int inflight;
 
+	if (!blk_queue_io_stat(q))
+		return sprintf(buf, "io accounting is disabled\n");
+
 	if (queue_is_mq(q))
 		inflight = blk_mq_in_flight(q, bdev);
 	else
@@ -1207,6 +1210,8 @@ 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;
+		if (!blk_queue_io_stat(gp->queue))
+			continue;
 		if (queue_is_mq(gp->queue))
 			inflight = blk_mq_in_flight(gp->queue, hd);
 		else
-- 
2.31.1