autoresize of overlay

Hello …

I have installed volumio-2.348-2017-12-22-pi on my old raspi B+. After first boot overlay partition is still really small.

root@volumio:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk0p2  2.2G  625M  1.5G  30% /imgpart
/dev/loop0      277M  277M     0 100% /static
overlay         262M  188M   54M  78% /
devtmpfs        478M     0  478M   0% /dev
tmpfs           489M  4.0K  489M   1% /dev/shm
tmpfs           489M   17M  472M   4% /run
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           489M     0  489M   0% /sys/fs/cgroup
tmpfs           489M   32K  489M   1% /tmp
tmpfs           489M     0  489M   0% /var/spool/cups
tmpfs            20M  1.6M   19M   8% /var/log
tmpfs           489M     0  489M   0% /var/spool/cups/tmp
/dev/mmcblk0p1   61M   35M   26M  58% /boot
tmpfs            98M     0   98M   0% /run/user/0

SD card is 8GiB and parted reporting this

root@volumio:~# parted -s /dev/mmcblk0 unit MB print free
Model: SD SL08G (sd/mmc)
Disk /dev/mmcblk0: 7948MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
        0.00MB  0.00MB  0.00MB           Free Space
 1      0.00MB  64.0MB  64.0MB  primary  fat32        boot, lba
 2      64.0MB  2500MB  2436MB  primary  ext4
 3      2500MB  7948MB  5448MB  primary  ext4
        7948MB  7948MB  0.21MB           Free Space

Where is used partition 3 and why is overlay still small?