ioctl:
fs/crypto provides ready functions to be called from the
ioctl interface, so to enable encryption, use them.

property:
adds a property called 'btrfs.encrypt' to that encryption
context can be saved.

encoder:
Defines BTRFS_ENCRYPT_FSCRYPTV1, as an encoder type to
encrypt / decrypt the file data pages.

fname encryption:
As of now does not support the file-name encryption

Signed-off-by: Anand Jain <anand.jain@oracle.com>