Resize encrypted btrfs root partition

I want to resize my encrypted btrfs root partition to be able to also install Windows 11 alongside Manjaro.

Is there any easy way to do this? I have seen forum posts about this, but all of them involve backing up and restoring data.

inxi --admin --verbosity=7 --filter --width                                                                                                        ✔ 
System:
  Kernel: 6.0.8-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.2.0
    parameters: BOOT_IMAGE=/@/boot/vmlinuz-6.0-x86_64
    root=UUID=4ee418e8-ca35-4a5f-9a96-1eb3cf16f3b0 rw rootflags=subvol=@ rhgb
    quiet mitigations=off "acpi_osi=Windows 2022" quiet
    cryptdevice=UUID=9a915a82-f1ac-4fda-a713-befca1c3f997:luks-9a915a82-f1ac-4fda-a713-befca1c3f997
    root=/dev/mapper/luks-9a915a82-f1ac-4fda-a713-befca1c3f997
    udev.log_priority=3 loglevel=0 udev.log_level=3 nowatchdog nmi_watchdog=0
  Desktop: KDE Plasma v: 5.26.3 tk: Qt v: 5.15.7 wm: kwin_wayland vt: 2
    dm: SDDM Distro: Manjaro Linux base: Arch Linux
Machine:
  Type: Laptop System: HP product: HP Laptop 15s-eq2xxx v: N/A
    serial: <superuser required> Chassis: type: 10 serial: <superuser required>
  Mobo: HP model: 887A v: 59.20 serial: <superuser required> UEFI: AMI
    v: F.26 date: 08/29/2022
Battery:
  ID-1: BAT0 charge: 34.1 Wh (80.2%) condition: 42.5/42.5 Wh (100.0%)
    volts: 12.1 min: 11.3 model: HP Primary type: Li-ion serial: <filter>
    status: discharging
Memory:
  RAM: total: 14.96 GiB used: 6.62 GiB (44.3%)
  RAM Report: permissions: Unable to run dmidecode. Root privileges required.
CPU:
  Info: model: AMD Ryzen 5 5500U with Radeon Graphics bits: 64 type: MT MCP
    arch: Zen 2 gen: 3 level: v3 note: check built: 2020-22
    process: TSMC n7 (7nm) family: 0x17 (23) model-id: 0x68 (104) stepping: 1
    microcode: 0x8608103
  Topology: cpus: 1x cores: 6 tpc: 2 threads: 12 smt: enabled cache:
    L1: 384 KiB desc: d-6x32 KiB; i-6x32 KiB L2: 3 MiB desc: 6x512 KiB L3: 8 MiB
    desc: 2x4 MiB
  Speed (MHz): avg: 1399 high: 1400 min/max: 1400/4056 boost: disabled
    scaling: driver: acpi-cpufreq governor: powersave cores: 1: 1400 2: 1400
    3: 1400 4: 1399 5: 1400 6: 1397 7: 1397 8: 1400 9: 1400 10: 1400 11: 1395
    12: 1400 bogomips: 50325
  Flags: 3dnowprefetch abm adx aes aperfmperf apic arat avic avx avx2 bmi1
    bmi2 bpext cat_l3 cdp_l3 clflush clflushopt clwb clzero cmov cmp_legacy
    constant_tsc cpb cppc cpuid cqm cqm_llc cqm_mbm_local cqm_mbm_total
    cqm_occup_llc cr8_legacy cx16 cx8 de decodeassists extapic extd_apicid
    f16c flushbyasid fma fpu fsgsbase fxsr fxsr_opt ht hw_pstate ibpb ibrs ibs
    irperf lahf_lm lbrv lm mba mca mce misalignsse mmx mmxext monitor movbe
    msr mtrr mwaitx nonstop_tsc nopl npt nrip_save nx osvw overflow_recov pae
    pat pausefilter pclmulqdq pdpe1gb perfctr_core perfctr_llc perfctr_nb
    pfthreshold pge pni popcnt pse pse36 rapl rdpid rdpru rdrand rdseed rdt_a
    rdtscp rep_good sep sha_ni skinit smap smca smep ssbd sse sse2 sse4_1
    sse4_2 sse4a ssse3 stibp succor svm svm_lock syscall tce topoext tsc
    tsc_scale umip v_spec_ctrl v_vmsave_vmload vgif vmcb_clean vme vmmcall
    wbnoinvd wdt xgetbv1 xsave xsavec xsaveerptr xsaveopt xsaves
  Vulnerabilities:
  Type: itlb_multihit status: Not affected
  Type: l1tf status: Not affected
  Type: mds status: Not affected
  Type: meltdown status: Not affected
  Type: mmio_stale_data status: Not affected
  Type: retbleed status: Vulnerable
  Type: spec_store_bypass status: Vulnerable
  Type: spectre_v1 status: Vulnerable: __user pointer sanitization and
    usercopy barriers only; no swapgs barriers
  Type: spectre_v2 status: Vulnerable, IBPB: disabled, STIBP: disabled,
    PBRSB-eIBRS: Not affected
  Type: srbds status: Not affected
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: AMD Lucienne vendor: Hewlett-Packard driver: amdgpu v: kernel
    arch: GCN-5.1 code: Vega-2 process: TSMC n7 (7nm) built: 2018-21 pcie: gen: 3
    speed: 8 GT/s lanes: 16 link-max: gen: 4 speed: 16 GT/s ports:
    active: eDP-1 empty: HDMI-A-1 bus-ID: 03:00.0 chip-ID: 1002:164c
    class-ID: 0300 temp: 32.0 C
  Device-2: Chicony HP TrueVision HD Camera type: USB driver: uvcvideo
    bus-ID: 1-3:2 chip-ID: 04f2:b6f1 class-ID: 0e02 serial: <filter>
  Display: wayland server: X.org v: 1.21.1.4 with: Xwayland v: 22.1.5
    compositor: kwin_wayland driver: X: loaded: amdgpu unloaded: modesetting
    alternate: fbdev,vesa dri: radeonsi gpu: amdgpu display-ID: 0
  Monitor-1: eDP-1 res: 1476x830 size: N/A modes: N/A
  API: OpenGL v: 4.6 Mesa 22.2.3 renderer: AMD Radeon Graphics (renoir LLVM
    14.0.6 DRM 3.48 6.0.8-1-MANJARO) direct render: Yes
Audio:
  Device-1: AMD Renoir Radeon High Definition Audio vendor: Hewlett-Packard
    driver: snd_hda_intel v: kernel pcie: gen: 3 speed: 8 GT/s lanes: 16
    link-max: gen: 4 speed: 16 GT/s bus-ID: 03:00.1 chip-ID: 1002:1637
    class-ID: 0403
  Device-2: AMD ACP/ACP3X/ACP6x Audio Coprocessor vendor: Hewlett-Packard
    driver: snd_rn_pci_acp3x v: kernel
    alternate: snd_pci_acp3x,snd_pci_acp5x,snd_pci_acp6x,snd_acp_pci,snd_rpl_pci_acp6x,snd_sof_amd_renoir
    pcie: gen: 3 speed: 8 GT/s lanes: 16 link-max: gen: 4 speed: 16 GT/s
    bus-ID: 03:00.5 chip-ID: 1022:15e2 class-ID: 0480
  Device-3: AMD Family 17h/19h HD Audio vendor: Hewlett-Packard
    driver: snd_hda_intel v: kernel pcie: gen: 3 speed: 8 GT/s lanes: 16
    link-max: gen: 4 speed: 16 GT/s bus-ID: 03:00.6 chip-ID: 1022:15e3
    class-ID: 0403
  Sound API: ALSA v: k6.0.8-1-MANJARO running: yes
  Sound Server-1: JACK v: 1.9.21 running: no
  Sound Server-2: PulseAudio v: 16.1 running: no
  Sound Server-3: PipeWire v: 0.3.59 running: yes
Network:
  Device-1: Realtek RTL8821CE 802.11ac PCIe Wireless Network Adapter
    vendor: Hewlett-Packard driver: rtw_8821ce v: N/A modules: rtw88_8821ce pcie:
    gen: 1 speed: 2.5 GT/s lanes: 1 port: f000 bus-ID: 01:00.0
    chip-ID: 10ec:c821 class-ID: 0280
  IF: wlo1 state: up mac: <filter>
  IP v4: <filter> type: dynamic noprefixroute scope: global
    broadcast: <filter>
  IP v6: <filter> type: noprefixroute scope: link
  WAN IP: <filter>
Bluetooth:
  Device-1: Realtek Bluetooth Radio type: USB driver: btusb v: 0.8
    bus-ID: 1-4:3 chip-ID: 0bda:b00e class-ID: e001 serial: <filter>
  Report: rfkill ID: hci0 rfk-id: 6 state: up address: see --recommends
Logical:
  Message: No logical block device data found.
  Device-1: luks-9a915a82-f1ac-4fda-a713-befca1c3f997 maj-min: 254:0
    type: LUKS dm: dm-0 size: 931.21 GiB
  Components:
  p-1: nvme0n1p2 maj-min: 259:2 size: 931.22 GiB
RAID:
  Message: No RAID data found.
Drives:
  Local Storage: total: 931.51 GiB used: 362.48 GiB (38.9%)
  SMART Message: Unable to run smartctl. Root privileges required.
  ID-1: /dev/nvme0n1 maj-min: 259:0 vendor: Samsung
    model: SSD 970 EVO Plus 1TB size: 931.51 GiB block-size: physical: 512 B
    logical: 512 B speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter>
    rev: 2B2QEXM7 temp: 38.9 C scheme: GPT
  Message: No optical or floppy data found.
Partition:
  ID-1: / raw-size: 931.21 GiB size: 731.02 GiB (78.50%)
    used: 362.18 GiB (49.5%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
    mapped: luks-9a915a82-f1ac-4fda-a713-befca1c3f997 label: N/A
    uuid: 4ee418e8-ca35-4a5f-9a96-1eb3cf16f3b0
  ID-2: /boot/efi raw-size: 300 MiB size: 299.4 MiB (99.80%)
    used: 299.4 MiB (100.0%) fs: vfat dev: /dev/nvme0n1p1 maj-min: 259:1
    label: NO_LABEL uuid: 90B7-5322
  ID-3: /home raw-size: 931.21 GiB size: 731.02 GiB (78.50%)
    used: 362.18 GiB (49.5%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
    mapped: luks-9a915a82-f1ac-4fda-a713-befca1c3f997 label: N/A
    uuid: 4ee418e8-ca35-4a5f-9a96-1eb3cf16f3b0
  ID-4: /var/cache raw-size: 931.21 GiB size: 731.02 GiB (78.50%)
    used: 362.18 GiB (49.5%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
    mapped: luks-9a915a82-f1ac-4fda-a713-befca1c3f997 label: N/A
    uuid: 4ee418e8-ca35-4a5f-9a96-1eb3cf16f3b0
  ID-5: /var/log raw-size: 931.21 GiB size: 731.02 GiB (78.50%)
    used: 362.18 GiB (49.5%) fs: btrfs dev: /dev/dm-0 maj-min: 254:0
    mapped: luks-9a915a82-f1ac-4fda-a713-befca1c3f997 label: N/A
    uuid: 4ee418e8-ca35-4a5f-9a96-1eb3cf16f3b0
Swap:
  Alert: No swap data was found.
Unmounted:
  Message: No unmounted partitions found.
USB:
  Hub-1: 1-0:1 info: Hi-speed hub with single TT ports: 4 rev: 2.0
    speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Hub-2: 1-2:10 info: VIA Labs USB2.0 Hub ports: 4 rev: 2.1 speed: 480 Mb/s
    chip-ID: 2109:2817 class-ID: 0900
  Device-1: 1-2.2:11 info: USB OPTICAL MOUSE type: Mouse
    driver: hid-generic,usbhid interfaces: 1 rev: 1.1 speed: 1.5 Mb/s
    power: 100mA chip-ID: 30fa:0400 class-ID: 0301
  Device-2: 1-3:2 info: Chicony HP TrueVision HD Camera type: Video
    driver: uvcvideo interfaces: 2 rev: 2.0 speed: 480 Mb/s power: 500mA
    chip-ID: 04f2:b6f1 class-ID: 0e02 serial: <filter>
  Device-3: 1-4:3 info: Realtek Bluetooth Radio type: Bluetooth driver: btusb
    interfaces: 2 rev: 1.1 speed: 12 Mb/s power: 500mA chip-ID: 0bda:b00e
    class-ID: e001 serial: <filter>
  Hub-3: 2-0:1 info: Super-speed hub ports: 2 rev: 3.1 speed: 10 Gb/s
    chip-ID: 1d6b:0003 class-ID: 0900
  Hub-4: 2-2:5 info: VIA Labs USB3.0 Hub ports: 4 rev: 3.2 speed: 5 Gb/s
    chip-ID: 2109:0817 class-ID: 0900
  Hub-5: 3-0:1 info: Hi-speed hub with single TT ports: 4 rev: 2.0
    speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Hub-6: 4-0:1 info: Super-speed hub ports: 2 rev: 3.1 speed: 10 Gb/s
    chip-ID: 1d6b:0003 class-ID: 0900
Sensors:
  System Temperatures: cpu: 33.5 C mobo: N/A gpu: amdgpu temp: 32.0 C
  Fan Speeds (RPM): fan-1: 0 fan-2: 0
Info:
  Processes: 420 Uptime: 1d 13h 25m wakeups: 9009 Init: systemd v: 251
  default: graphical tool: systemctl Compilers: gcc: 12.2.0 clang: 14.0.6
  Packages: 1668 pm: nix-default pkgs: 47 pm: nix-sys pkgs: 0 pm: nix-usr
  pkgs: 2 pm: pacman pkgs: 1616 libs: 444 tools: pamac pm: flatpak pkgs: 3
  Shell: Zsh v: 5.9 default: Bash v: 5.1.16 running-in: yakuake inxi: 3.3.23

Reducing the size of a partition already involves some risk of losing data. Such risk is presumably quite higher on an encrypted partition.

For an unencrypted btrfs this is easy.

Do you have encryption inside btrfs or btrfs inside encryption ?

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I have btrfs inside encryption.