df hangs / VirtualBox unable to start

i'm experiencing what I think are issues with btrfs and suspend/resume, after a resume, I can no longer start any virtual machines in virtualbox also, if I attempt a df command, it will just hang. Both of these events work fine
prior to suspend resume as well as before I migrated to btrfs.

Things that I've tried

btrfs fi sync /home
btrfs scrub start /home
btrfs fi df /home (no errors reported)
btrfs fi show /home (Btrfs v3.14.2-dirty during scrub)

The only thing that I have found that fixes the problem is a total system reboot

Additional info
kernel 3.15.1-1-ARCH
btrfsprogs v3.14.2

let me know what other information I can provide to figure out the cause.

-Kevin Brandstatter