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: 74d46992 ("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>

block/partition-generic.c

@@ -51,6 +51,12 @@ const char *bdevname(struct block_device *bdev, char *buf)
 
 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

include/linux/bio.h

@@ -511,6 +511,7 @@ void zero_fill_bio(struct bio *bio);
 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 extern unsigned int bvec_nr_vecs(unsigned short idx);
+extern const char *bio_devname(struct bio *bio, char *buffer);
 
 #define bio_set_dev(bio, bdev) 			\
 do {						\
@@ -529,9 +530,6 @@ do {						\
 #define bio_dev(bio) \
 	disk_devt((bio)->bi_disk)
 
-#define bio_devname(bio, buf) \
-	__bdevname(bio_dev(bio), (buf))
-
 #ifdef CONFIG_BLK_CGROUP
 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 void bio_disassociate_task(struct bio *bio);