block: simplify diskstats_show

Just use xa_for_each to iterate over the partitions as there is no need
to grab a reference to each partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index 5726714..cbfe1ff 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1236,11 +1236,11 @@ const struct device_type disk_type = {
 static int diskstats_show(struct seq_file *seqf, void *v)
 {
        struct gendisk *gp = v;
-       struct disk_part_iter piter;
        struct block_device *hd;
        char buf[BDEVNAME_SIZE];
        unsigned int inflight;
        struct disk_stats stat;
+       unsigned long idx;
 
        /*
        if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
@@ -1250,8 +1250,10 @@ static int diskstats_show(struct seq_file *seqf, void *v)
                                "\n\n");
        */
 
-       disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
-       while ((hd = disk_part_iter_next(&piter))) {
+       rcu_read_lock();
+       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);
@@ -1294,7 +1296,7 @@ static int diskstats_show(struct seq_file *seqf, void *v)
                                                 NSEC_PER_MSEC)
                        );
        }
-       disk_part_iter_exit(&piter);
+       rcu_read_unlock();
 
        return 0;
 }