This is a changeset adding encryption to btrfs. It is not complete; it
does not support inline data or verity or authenticated encryption. It
is primarily intended as a proof that the fscrypt extent encryption
changeset it builds on work.
As per the design doc refined in the fall of last year [1], btrfs
encryption has several steps: first, adding extent encryption to fscrypt
and then btrfs; second, adding authenticated encryption support to the
block layer, fscrypt, and then btrfs; and later adding potentially the
ability to change the key used by a directory (either for all data or
just newly written data) and/or allowing use of inline extents and
verity items in combination with encryption and/or enabling send/receive
of encrypted volumes. As such, this change is only the first step and is
unsafe.
This cha