Changes for 4.12: - various code cleanups - introduce GETFSMAP ioctl - various refactoring - avoid dio reads past eof - fix memory corruption and other errors with fragmented directory blocks - fix accidental userspace memory corruptions - publish fs uuid in superblock - make fstrim terminatable - fix race between quotaoff and in-core inode creation - Avoid use-after-free when finishing up w/ buffer heads - Reserve enough space to handle bmap tree resizing during cow remap