Just in case someone wants to try to reproduce this...
TC5 X86_64 Live Desktop, installed with all defaults, firstboot came up fine, was working fine most of the day.
btrfs-convert on lv_home went OK, no errors. btrfs-convert on lv_root segfaults. I've reproduced this twice.
No real idea how to troubleshoot this or supply more info. But I've put a dmesg, the abrt file, and messages into this bug report.
https://bugzilla.redhat.com/show_bug.cgi?id=821212
Many udisksd "Error opening /etc/crypttab file" messages. No encryption used on this disk on any partition.
When mounting with or without -o recovery, I get a panic.
btrfs-convert -r appears to work, it says rollback complete, and it mounts fine.
Chris Murphy