root@debian8:~# lvextend /dev/vg00/ext4fs -L +10G
  Size of logical volume vg00/ext4fs changed from 60.00 GiB (15360 extents) to 70.00 GiB (17920 extents).
  Logical volume ext4fs successfully resized
root@debian8:~# resize2fs /dev/vg00/ext4fs 
resize2fs 1.42.12 (29-Aug-2014)
Filesystem at /dev/vg00/ext4fs is mounted on /mnt/ext4fs; on-line resizing required
old_desc_blocks = 4, new_desc_blocks = 5
The filesystem on /dev/vg00/ext4fs is now 18350080 (4k) blocks long.