Btrfs support in Fedora has been interesting going all the way
back to the Fedora 13 release where it gained support for Linux
system roll-backs by taking advantage of the Btrfs copy-on-write
snapshots within Yum.
Btrfs was supposed to become the default file-system in Fedora
16 but in the end the switch was postponed since a proper fsck
utility for Btrfs was not ready, among other blocking bugs.