My root partition was filling up, with only 500 mbs left, I wanted to resize my root partition from 20 Gb to 40Gb
So I resized my partition by using these steps:
Using Gparted to resize another partition to give space for the EXT4
Using fdisk, deleting the root partition (on /dev/sda2), and creating it again using the new size
resize2fs /dev/sda2
Updating grub2
But now the problem is that although I can boot in my new partition and the new partition shows it is 40Gb, but the free size was still 500mb. So I booted from a LiveCD and checked with e2fsck -p /dev/sda2, it reported clean. So I added the -f flag (force check), still, the drive is full.