hfs: use bdev_nr_sectors instead of open coding it

Use the proper helper to read the block device size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211018101130.1838532-16-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/hfs/mdb.c

@@ -36,7 +36,7 @@ static int hfs_get_last_session(struct super_block *sb,
 
 	/* default values */
 	*start = 0;
-	*size = i_size_read(sb->s_bdev->bd_inode) >> 9;
+	*size = bdev_nr_sectors(sb->s_bdev);
 
 	if (HFS_SB(sb)->session >= 0) {
 		struct cdrom_tocentry te;