virtio_balloon: Fix memory leaks on errors in virtballoon_probe()

We forget to put the inode and unmount the kernfs used for compaction.

Fixes: 71994620 ("virtio_balloon: replace oom notifier with shrinker")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Liang Li <liang.z.li@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200205163402.42627-3-david@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_balloon.c

@@ -903,8 +903,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
 	if (IS_ERR(vb->vb_dev_info.inode)) {
 		err = PTR_ERR(vb->vb_dev_info.inode);
-		kern_unmount(balloon_mnt);
-		goto out_del_vqs;
+		goto out_kern_unmount;
 	}
 	vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
 #endif
@@ -915,13 +914,13 @@ static int virtballoon_probe(struct virtio_device *vdev)
 		 */
 		if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
 			err = -ENOSPC;
-			goto out_del_vqs;
+			goto out_iput;
 		}
 		vb->balloon_wq = alloc_workqueue("balloon-wq",
 					WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
 		if (!vb->balloon_wq) {
 			err = -ENOMEM;
-			goto out_del_vqs;
+			goto out_iput;
 		}
 		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
 		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
@@ -955,6 +954,12 @@ static int virtballoon_probe(struct virtio_device *vdev)
 out_del_balloon_wq:
 	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
 		destroy_workqueue(vb->balloon_wq);
+out_iput:
+#ifdef CONFIG_BALLOON_COMPACTION
+	iput(vb->vb_dev_info.inode);
+out_kern_unmount:
+	kern_unmount(balloon_mnt);
+#endif
 out_del_vqs:
 	vdev->config->del_vqs(vdev);
 out_free_vb: