Google Is Exploring Potentially Using Btrfs In Android
A Google engineer has confirmed they are "evaluating btrfs for its potential use in android." This statement was made when the Googler, Filip Bystricky, was inquiring about Btrfs' lack of native encryption support.
Btrfs lacking native file-based encryption makes it a non-starter for them. Android's primary file-system is current EXT4, which in the past few years has supported native encryption via what's now known as fscrypt in the Linux kernel and is also shared by the Flash-Friendly File-System (F2FS).
Google's interest in Btrfs encryption, as acknowledged in the Btrfs mailing list, will perhaps motivate some developers to get going with this work. There were some patches for Btrfs encryption last year but were incomplete and never merged.