Disk expansion on Ubuntu 20.04.1 LTS on GCP Compute Engine

Premise

--As the document says, I took a snapshot before work just in case. --The partition has not changed since the VM was created. --See here for command execution.

work

1. Compute Engine> Disk
2. Select the disk to be expanded
3. "Edit" on the upper right
4. Change the value of Properties> Size and click "Save"
5. Connect with SSH and execute the following command
   1. sudo apt -y install cloud-guest-utils
   2. sudo growpart /dev/sda 1
   3. sudo resize2fs /dev/sda 1 --I got an error due to busy or something and couldn't solve it. --Since it is ext4, this seems to be fine, but even if I investigate and execute other commands, it does not solve. --In the case of Amazon EC2 somewhere, I was running resize2fs in some configuration file and it was said that it would be solved by restarting, so I restarted.
6. As a result of the reboot, the available capacity has increased.