nfs/blocklayout: use bdev_nr_bytes 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/20211018101130.1838532-19-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/nfs/blocklayout/dev.c

@@ -252,7 +252,7 @@ bl_parse_simple(struct nfs_server *server, struct pnfs_block_dev *d,
 	d->bdev = bdev;
 
 
-	d->len = i_size_read(d->bdev->bd_inode);
+	d->len = bdev_nr_bytes(d->bdev);
 	d->map = bl_map_simple;
 
 	printk(KERN_INFO "pNFS: using block device %s\n",
@@ -367,7 +367,7 @@ bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
 		return PTR_ERR(bdev);
 	d->bdev = bdev;
 
-	d->len = i_size_read(d->bdev->bd_inode);
+	d->len = bdev_nr_bytes(d->bdev);
 	d->map = bl_map_simple;
 	d->pr_key = v->scsi.pr_key;