ubifs: Add missing iput if do_tmpfile() failed in rename whiteout

whiteout inode should be put when do_tmpfile() failed if inode has been
initialized. Otherwise we will get following warning during umount:
  UBIFS error (ubi0:0 pid 1494): ubifs_assert_failed [ubifs]: UBIFS
  assert failed: c->bi.dd_growth == 0, in fs/ubifs/super.c:1930
  VFS: Busy inodes after unmount of ubifs. Self-destruct in 5 seconds.

Fixes: 9e0a1ff ("ubifs: Implement RENAME_WHITEOUT")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/dir.c

@@ -432,6 +432,8 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 	make_bad_inode(inode);
 	if (!instantiated)
 		iput(inode);
+	else if (whiteout)
+		iput(*whiteout);
 out_budg:
 	ubifs_release_budget(c, &req);
 	if (!instantiated)