fs/affs: release old buffer head on error path

The reference count of the old buffer head should be decremented on path
that fails to get the new buffer head.

Fixes: 6b465766 ("fs/affs: add rename exchange")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/affs/namei.c

@@ -460,8 +460,10 @@ affs_xrename(struct inode *old_dir, struct dentry *old_dentry,
 		return -EIO;
 
 	bh_new = affs_bread(sb, d_inode(new_dentry)->i_ino);
-	if (!bh_new)
+	if (!bh_new) {
+		affs_brelse(bh_old);
 		return -EIO;
+	}
 
 	/* Remove old header from its parent directory. */
 	affs_lock_dir(old_dir);