Prerequisites
Plug-In your USB Stick to your maschine. Click with right mouse on the Image and choice Make bootable USB stick.
After rebooted your maschine and booted with Linux Mint 19.3, please open a terminal.
Identify encrypted device
Identify encrypted device - /dev/nvme0n1
partition in this example.
$ lsblk -f /dev/nvme0n1
NAME FSTYPE LABEL UUID MOUNTPOINT
nvme0n1
├─nvme0n1p1 vfat D1EC-CB38 /boot/efi
├─nvme0n1p2 ext4 6706d5ab-ded4-4a99-a17a-39db1aa75761 /boot
└─nvme0n1p3 crypto_LUKS 12a034f9-1a0a-4e4e-97e2-2731620534b9
└─nvme0n1p3_crypt LVM2_member jxFZEZ-nZ0o-tSG1-wkfQ-ZBmw-gpcu-xWbGie
├─mint--vg-root ext4 7e3fc579-a6e4-49c2-bc69-d5f66cca45c4 /
└─mint--vg-swap_1 swap 4115a08a-bf78-4415-9209-36deadd7ed3b [SWAP]
Open LUKS device
Open encrypted /dev/nvme0n1p3
device and set up encrypted_device
mapping.
$ cryptsetup luksOpen /dev/nvme0n1p3 encrypted_device
Enter passphrase for /dev/nvme0n1p3: ****************
Identify volume group
Identify volume group - mint-vg
in this example.
$ vgs
VG #PV #LV #SN Attr VSize VFree
mint-vg 1 2 0 wz--n- <475,72g <1,72g
List logical volumes
List logical volumes on identified mint-vg
volume group.
$ lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root mint-vg -wi-ao---- 410,00g
swap_1 mint-vg -wi-ao---- 64,00g
Activate logical volumes
Activate volume group.
$ lvchange -ay mint-vg
Shrink encrypted file system
Attach the encrypted file system for testing
$ mkdir /media/mint--vg-root & mount /dev/mapper/mint--vg-root /media/mint--vg-root
$ ls -la /media/mint--vg-root
total 108
drwxr-xr-x 24 root root 4096 Feb 14 19:58 .
drwxr-xr-x 24 root root 4096 Feb 14 19:58 ..
drwxr-xr-x 2 root root 4096 Feb 14 19:58 bin
drwxr-xr-x 5 root root 4096 Feb 13 10:52 boot
drwxr-xr-x 2 root root 4096 Feb 6 10:34 cdrom
drwx------ 3 root root 4096 Feb 12 11:47 .config
drwxr-xr-x 21 root root 4700 Feb 14 20:39 dev
drwxr-xr-x 172 root root 12288 Feb 14 20:35 etc
drwxr-xr-x 3 root root 4096 Feb 6 10:34 home
lrwxrwxrwx 1 root root 33 Feb 13 10:51 initrd.img -> boot/initrd.img-4.15.0-43-generic
lrwxrwxrwx 1 root root 32 Feb 13 10:51 initrd.img.old -> boot/initrd.img-5.3.0-26-generic
drwxr-xr-x 25 root root 4096 Feb 12 13:20 lib
drwxr-xr-x 2 root root 4096 Feb 12 13:20 lib64
drwx------ 2 root root 16384 Feb 6 10:32 lost+found
drwxr-xr-x 3 root root 4096 Feb 14 19:58 media
drwxr-xr-x 2 root root 4096 Dec 13 17:12 mnt
drwxr-xr-x 5 root root 4096 Feb 12 15:27 opt
dr-xr-xr-x 341 root root 0 Feb 14 20:39 proc
drwx------ 11 root root 4096 Feb 14 20:35 root
drwxr-xr-x 37 root root 1180 Feb 14 20:39 run
drwxr-xr-x 2 root root 12288 Feb 12 14:21 sbin
drwxr-xr-x 2 root root 4096 Dec 13 17:12 srv
dr-xr-xr-x 13 root root 0 Feb 14 20:39 sys
drwxrwxrwt 15 root root 4096 Feb 14 20:50 tmp
drwxr-xr-x 11 root root 4096 Dec 13 17:11 usr
drwxr-xr-x 12 root root 4096 Feb 12 11:41 var
lrwxrwxrwx 1 root root 30 Feb 13 10:51 vmlinuz -> boot/vmlinuz-4.15.0-43-generic
lrwxrwxrwx 1 root root 29 Feb 13 10:51 vmlinuz.old -> boot/vmlinuz-5.3.0-26-generic
Umount the encrypted file system.
$ umount /media/mint--vg-root
Shrinking both logical volumes and filesystem
$ lvreduce --resizefs --size -410G /dev/mapper/mint--vg-root
Deactivate active volume group.
$ lvchange -an mint-vg
Close LUKS device
Remove the encrypted_device
mapping
$ cryptsetup luksClose encrypted_device
Now you can reboot your maschine as normal.