*** Make sure you have a back up prior to proceeding. ***
- Boot into rescue mode.
- Unmount partition if mounted and check disk:
umount /dev/sda1
e2fsck -vn /dev/sda1 - Delete /dev/sda1 partition and create a bigger one with fdisk:
fdisk /dev/sda
- Recreate the partition /dev/sda1 with the starting point at the default location and the ending point at highest possible cylinder. (Note: if you are extending by merging two partitions, the data in the second partition is lost so make sure to backup data you need.)
- Run partprobe and resize2fs utility with no size arguments:
partprobe /dev/sda
resize2fs /dev/sda1 - Reboot and check everything in file-system is intact.