nbd: use bd_set_size when updating disk size

commit 9e2b1967 upstream.

When we stopped relying on the bdev everywhere I broke updating the
block device size on the fly, which ceph relies on.  We can't just do
set_capacity, we also have to do bd_set_size so things like parted will
notice the device size change.

Fixes: 29eaadc0 ("nbd: stop using the bdev everywhere")
cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/block/nbd.c

@@ -234,9 +234,18 @@ static void nbd_size_clear(struct nbd_device *nbd)
 static void nbd_size_update(struct nbd_device *nbd)
 {
 	struct nbd_config *config = nbd->config;
+	struct block_device *bdev = bdget_disk(nbd->disk, 0);
+
 	blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 	set_capacity(nbd->disk, config->bytesize >> 9);
+	if (bdev) {
+		if (bdev->bd_disk)
+			bd_set_size(bdev, config->bytesize);
+		else
+			bdev->bd_invalidated = 1;
+		bdput(bdev);
+	}
 	kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 }
 
@@ -1114,7 +1123,6 @@ static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *b
 	if (ret)
 		return ret;
 
-	bd_set_size(bdev, config->bytesize);
 	if (max_part)
 		bdev->bd_invalidated = 1;
 	mutex_unlock(&nbd->config_lock);