btrfs_cont_expand
int btrfs_cont_expand(struct btrfs_inode *inode, loff_t oldsize, loff_t size);
ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, end_pos);
ret = btrfs_cont_expand(BTRFS_I(inode), i_size_read(inode),
ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, newsize);
ret = btrfs_cont_expand(BTRFS_I(inode), inode->i_size, destoff);