I believe this was fixed with the following upstream commit. This now in vivid.
commit 3d84be799194147e04c0e3129ed44a948773b80a Author: Forrest Liu <email address hidden> Date: Wed Feb 11 14:24:12 2015 +0800
Btrfs: fix BUG_ON in btrfs_orphan_add() when delete unused block group
I believe this was fixed with the following upstream commit. This now in vivid.
commit 3d84be799194147 e04c0e3129ed44a 948773b80a
Author: Forrest Liu <email address hidden>
Date: Wed Feb 11 14:24:12 2015 +0800
Btrfs: fix BUG_ON in btrfs_orphan_add() when delete unused block group