Package: btrfs-tools Version: 4.1.2-1 Subvol sync has "been broken since 4.1.2, due to a reversed condition it returned immediately instead of waiting"
https://btrfs.wiki.kernel.org/index.php/Changelog#btrfs-progs_4.2.3_.28Oct_2015.29 Please update the btrfs-tools to 4.2.3 ASAP, because broken subvol sync is a data loss risk.
