block: reduce stack usage in diskstats_show

I have compiled the kernel with a cross compiler "hppa-linux-gnu-" v9.3.0
on x86-64 host machine. I got the following warning:

block/genhd.c: In function ‘diskstats_show’:
block/genhd.c:1227:1: warning: the frame size of 1688 bytes is larger
than 1280 bytes [-Wframe-larger-than=]
 1227  |  }

By Reduced the stack footprint by using the %pg printk specifier instead
of disk_name to remove the need for the on-stack buffer.
Signed-off-by: NAbd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -1111,7 +1111,6 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 {
 	struct gendisk *gp = v;
 	struct block_device *hd;
-	char buf[BDEVNAME_SIZE];
 	unsigned int inflight;
 	struct disk_stats stat;
 	unsigned long idx;
@@ -1134,15 +1133,14 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 		else
 			inflight = part_in_flight(hd);
 
-		seq_printf(seqf, "%4d %7d %s "
+		seq_printf(seqf, "%4d %7d %pg "
 			   "%lu %lu %lu %u "
 			   "%lu %lu %lu %u "
 			   "%u %u %u "
 			   "%lu %lu %lu %u "
 			   "%lu %u"
 			   "\n",
-			   MAJOR(hd->bd_dev), MINOR(hd->bd_dev),
-			   disk_name(gp, hd->bd_partno, buf),
+			   MAJOR(hd->bd_dev), MINOR(hd->bd_dev), hd,
 			   stat.ios[STAT_READ],
 			   stat.merges[STAT_READ],
 			   stat.sectors[STAT_READ],