Grow a Linux VM disk online: rescan, growpart, pvresize, lvextend and xfs_growfs
echo 1 > /sys/class/block/sda/device/rescan; growpart /dev/sda 3; pvresize /dev/sda3; lvextend -r -l +100%FREE /dev/vg/lv. Without LVM: resize2fs or xfs_growfs. All online.