Kernel Bug Tracker – Bug 38742
After hard power-off, btrfs cannot be recovered except booting 2.6.38 or below kernel
Last modified: 2013-04-30 16:48:43 UTC
Confirmed on linux-3.0 rc5, 22.214.171.124
See mailing list for more information. The OOPS symbols are exactly the same in every instance. Booting 2.6.38.x repairs the filesystem and makes it mountable again with later versions.
Closing, if this is still affecting you on a newer kernel please reopen.