Maybe try btrfs-progs-3.19rc3? You have the data backed up, and progs 3.18.2 fails so it seems worth a shot.
Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html