How to resize encrypted LVM

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1

Hello,

I have encrypted TW installed on 1TB SSD.

nvme0n1                                                259:0    0 931.5G  0 disk  
├─nvme0n1p1                                            259:1    0   512M  0 part  /boot/efi
└─nvme0n1p2                                            259:2    0   931G  0 part  
  └─cr_nvme-eui.e8238fa6bf530001001b448b4bf7cf83-part2 254:0    0   931G  0 crypt 
    ├─system-swap                                      254:1    0     2G  0 lvm   [SWAP]
    └─system-root                                      254:2    0   929G  0 lvm   /var
                                                                                  /usr/local
                                                                                  /srv
                                                                                  /root
                                                                                  /home
                                                                                  /opt
                                                                                  /boot/grub2/x86_64-efi
                                                                                  /boot/grub2/i386-pc
                                                                                  /.snapshots
                                                                                  /
blkid
/dev/mapper/system-root: UUID="1ac05f60-24d3-4df4-a60d-5d5f90f1a5f2" UUID_SUB="4507c579-7535-40bc-9311-cb3a2d4c924b" BLOCK_SIZE="4096" TYPE="btrfs"

I want to shrink system-root to 200GB. I cant find GUI app that can do that.
I have found some cmd tutorials but nothing with btrfs that I trust.

cryptsetup luksOpen /dev/nvme0n1p2 cryptdisk
vgscan --mknodes
vgchange -ay

I have booted live gparted, decrypted disk and activated LVM.
What to do next from cmd or is there app with GUI that can do that?

2

Resize filesystem below 200GB to have some safety margin; resize LV to the desired size; resize filesystem to fill new size. All that happens online. Something like

btrfs filesytem resize -250G /
lvresize -L -200G system/root
btrfs filesystem resize max /

There is no need for it, everything works online on running system. You can only resize mounted btrfs, so you need to mount and adjust commands for your mountpoint.

3

I have to be sure I will not mess up, I don’t have backup of OS…
Please can you double check am I doing it correctly.

system-root is Used 90GB of 838GB Available.

df -h
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 4.0M  8.0K  4.0M   1% /dev
tmpfs                    7.5G  1.4M  7.5G   1% /dev/shm
tmpfs                    3.0G  2.7M  3.0G   1% /run
/dev/mapper/system-root  930G   90G  838G  10% /
tmpfs                    7.5G   40K  7.5G   1% /tmp
/dev/mapper/system-root  930G   90G  838G  10% /.snapshots
/dev/mapper/system-root  930G   90G  838G  10% /boot/grub2/i386-pc
/dev/mapper/system-root  930G   90G  838G  10% /boot/grub2/x86_64-efi
/dev/mapper/system-root  930G   90G  838G  10% /opt
/dev/mapper/system-root  930G   90G  838G  10% /home
/dev/mapper/system-root  930G   90G  838G  10% /root
/dev/mapper/system-root  930G   90G  838G  10% /srv
/dev/mapper/system-root  930G   90G  838G  10% /usr/local
/dev/mapper/system-root  930G   90G  838G  10% /var
/dev/nvme0n1p1           511M  5.3M  506M   2% /boot/efi

I want to shrink filesystem to 180GB

btrfs filesystem resize -658G /

Shrinking LVM2 so it will be size 235GB

lvresize -L -603G /dev/mapper/system-root

Expanding btrfs to fill new LVM

btrfs filesystem resize max /
4

When the plus + or minus - prefix is used, the value is not an absolute size, but is relative and added or subtracted from the current size. So what you are doing is setting system-root to 729GB.