I believe this was fixed with the following upstream commit. This now in vivid.
commit 3d84be799194147e04c0e3129ed44a948773b80a Author: Forrest Liu <forre...@synology.com> Date: Wed Feb 11 14:24:12 2015 +0800 Btrfs: fix BUG_ON in btrfs_orphan_add() when delete unused block group -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1413008 Title: Kernel BUG shortly after mounting btrfs filesystem To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1413008/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs