linux - How to resize a partition to its maximum capacity after partitioning it to half of its capacity?

Resize disk partition to max disk size with cfdisk: (you are targeting device)

cfdisk /dev/xyz

Choose: Resize (max size should be default), Write, Quit. You can check changes with lsblk.

Now you have to resize the file system to match partition size: (you are targeting a partition)

resize2fs /dev/sdXY

You can check how it went with df -h.

If you are resizing a virtual disk (VMWare, ESXi, VirtualBox) and you don't want to restart the machine to see disk size changes, just scan the disk you resized: (you are targeting device)

echo 1 > /sys/class/block/sdX/device/rescan

Now you can resize the partition and file system, like I described in this post.