Btrfs: Implement new dir index format

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --cc fs/btrfs/btrfs_inode.h
Simple merge

diff --cc fs/btrfs/ctree.h
Simple merge

diff --cc fs/btrfs/dir-item.c
Simple merge

diff --cc fs/btrfs/inode-item.c
Simple merge

diff --cc fs/btrfs/inode.c
Simple merge

diff --cc fs/btrfs/ioctl.c
Simple merge

diff --cc fs/btrfs/transaction.c
Simple merge