block: display the correct diskname for bio

bio_devname use __bdevname to display the device name, and can
only show the major and minor of the part0,
Fix this by using disk_name to display the correct name.

Fixes: 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/partition-generic.c b/block/partition-generic.c
index 91622db..08dabcd 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -51,6 +51,12 @@
 
 EXPORT_SYMBOL(bdevname);
 
+const char *bio_devname(struct bio *bio, char *buf)
+{
+	return disk_name(bio->bi_disk, bio->bi_partno, buf);
+}
+EXPORT_SYMBOL(bio_devname);
+
 /*
  * There's very little reason to use this, you should really
  * have a struct block_device just about everywhere and use