Feat: Automatische Btrfs-Root-Erkennung und Subvolume-Migration (@, @home) hinzugefügt

Co-authored-by: Junie <junie@jetbrains.com>

AGENTS.md

@@ -24,6 +24,7 @@ Dieses Repository ist ein modulares, automatisiertes Setup- und Konfigurations-F
 ├── lib/                             # Wiederverwendbare Funktionsbibliotheken
 │   ├── utils.sh                     # Logging, Error-Traps, Benutzer- und Pfadermittlung, Backups
 │   ├── apt.sh                       # Deb822-Quellen, Keyrings (/etc/apt/keyrings), APT-Pinning, Paketinstallation
+│   ├── btrfs.sh                     # Btrfs Root- & Subvolume-Erkennung, Migration (@, @home), fstab-Verwaltung
 │   └── tui.sh                       # Whiptail-TUI-Menüs und Dialoge
 ├── config/                          # Konfigurationsdateien & Paketlisten
 │   ├── setup.conf                   # Globale Umgebungsvariablen und Standardwerte
@@ -132,6 +133,12 @@ Dieses Repository ist ein modulares, automatisiertes Setup- und Konfigurations-F
 - `install_apt_keyring "name" "url"`: Lädt einen GPG-Schlüssel herunter, de-armort ihn sauber und speichert ihn in `/etc/apt/keyrings/<name>.gpg`.
 - `install_packages_from_file "filepath"`: Liest eine `.list`-Datei ein (ignoriert Kommentare `#` und Leerzeilen) und installiert alle Pakete via `apt-get install -y`.
 
+### `lib/btrfs.sh`
+- `is_root_btrfs`: Prüft, ob das Root-Dateisystem auf Btrfs liegt.
+- `is_root_subvolume_configured`: Prüft, ob Root bereits in einem Subvolume (`@`) läuft.
+- `update_btrfs_fstab "fstab_file" "root_id"`: Aktualisiert Mount-Optionen in `/etc/fstab` für `@` und `@home`.
+- `check_and_setup_btrfs_subvolumes`: Erkennt flache Btrfs-Root-Volumes und migriert `/` und `/home` transparent in Subvolumes `@` und `@home`.
+
 ### `lib/tui.sh`
 - `tui_show_stage_selection`: Zeigt ein `whiptail` Checklist-Menü zur interaktiven Auswahl der auszuführenden Phasen.
 

README.md

@@ -62,6 +62,7 @@ sudo ./setup.sh --stages 04,05
 ├── lib/                             # Wiederverwendbare Hilfsbibliotheken
 │   ├── utils.sh                     # Logging, Error-Traps (set -euo pipefail), Root/User-Erkennung & Abfrage
 │   ├── apt.sh                       # APT-Keyring-Management (/etc/apt/keyrings/), Deb822, Pinning
+│   ├── btrfs.sh                     # Btrfs Root- & Subvolume-Erkennung, Migration (@, @home)
 │   └── tui.sh                       # Whiptail-Menüs und Dialoge
 ├── config/                          # Konfigurationsdateien & Paketlisten
 │   ├── setup.conf                   # Globale Variablen (Kernel, GRUB-Theme, Plymouth)

lib/btrfs.sh

@@ -0,0 +1,263 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# lib/btrfs.sh - Btrfs root volume detection, subvolume management & migration
+# ==============================================================================
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+# shellcheck source=lib/utils.sh
+source "$SCRIPT_DIR/lib/utils.sh"
+
+# Check if the root filesystem is Btrfs
+is_root_btrfs() {
+    local fstype
+    fstype="$(findmnt -n -o FSTYPE / 2>/dev/null || true)"
+    [[ "$fstype" == "btrfs" ]]
+}
+
+# Resolve the root block device (stripping any subvolume bracket suffix)
+get_root_btrfs_device() {
+    local dev
+    dev="$(findmnt -n -o SOURCE --canonical / 2>/dev/null || findmnt -n -o SOURCE / 2>/dev/null || true)"
+    dev="${dev%%\[*}"
+    echo "$dev"
+}
+
+# Resolve UUID of root filesystem
+get_root_btrfs_uuid() {
+    local uuid dev
+    uuid="$(findmnt -n -o UUID / 2>/dev/null || true)"
+    if [[ -z "$uuid" ]]; then
+        dev="$(get_root_btrfs_device)"
+        if [[ -n "$dev" && -b "$dev" ]]; then
+            uuid="$(blkid -s UUID -o value "$dev" 2>/dev/null || true)"
+        fi
+    fi
+    echo "$uuid"
+}
+
+# Check if /home is mounted on a separate filesystem / partition from /
+is_home_separate_filesystem() {
+    local root_dev home_dev
+    root_dev="$(get_root_btrfs_device)"
+    home_dev="$(findmnt -n -o SOURCE --canonical /home 2>/dev/null || findmnt -n -o SOURCE /home 2>/dev/null || true)"
+    home_dev="${home_dev%%\[*}"
+    if [[ -n "$home_dev" && -n "$root_dev" && "$home_dev" != "$root_dev" ]]; then
+        return 0
+    fi
+    return 1
+}
+
+# Check if root is already running from a dedicated subvolume (@ or @rootfs)
+is_root_subvolume_configured() {
+    local fsroot opts
+    fsroot="$(findmnt -n -o FSROOT / 2>/dev/null || true)"
+    opts="$(findmnt -n -o OPTIONS / 2>/dev/null || true)"
+    if [[ "$fsroot" == "/@" || "$fsroot" == "/@rootfs" ]] || \
+       [[ "$opts" =~ subvol=@ || "$opts" =~ subvol=/@ ]]; then
+        return 0
+    fi
+    return 1
+}
+
+# Update /etc/fstab to mount / with subvol=@ and /home with subvol=@home
+update_btrfs_fstab() {
+    local fstab_file="$1"
+    local root_id="$2"
+
+    [[ -f "$fstab_file" ]] || return 0
+
+    backup_file_or_dir "$fstab_file"
+
+    local tmp_fstab
+    tmp_fstab="$(mktemp)"
+
+    local found_root=0
+    local found_home=0
+    local root_spec="${root_id:-}"
+    local root_opts="defaults,subvol=@"
+
+    while IFS= read -r line || [[ -n "$line" ]]; do
+        # Retain comments and blank lines
+        if [[ "$line" =~ ^[[:space:]]*# || -z "${line// /}" ]]; then
+            echo "$line" >> "$tmp_fstab"
+            continue
+        fi
+
+        # Parse fields
+        local spec mnt type opts freq pass
+        read -r spec mnt type opts freq pass <<< "$line"
+
+        if [[ "$mnt" == "/" && "$type" == "btrfs" ]]; then
+            found_root=1
+            root_spec="${root_id:-$spec}"
+            local new_opts="$opts"
+            if [[ "$new_opts" =~ subvol= ]] || [[ "$new_opts" =~ subvolid= ]]; then
+                new_opts="$(echo "$new_opts" | sed -E 's/(subvol|subvolid)=[^,]*/subvol=@/g')"
+            else
+                new_opts="${new_opts},subvol=@"
+            fi
+            new_opts="$(echo "$new_opts" | sed -E -e 's/,,+/,/g' -e 's/^,//' -e 's/,$//')"
+            root_opts="$new_opts"
+            spec="$root_spec"
+            printf "%s\t%s\t%s\t%s\t%s\t%s\n" "$spec" "$mnt" "$type" "$new_opts" "${freq:-0}" "${pass:-0}" >> "$tmp_fstab"
+        elif [[ "$mnt" == "/home" && "$type" == "btrfs" ]]; then
+            found_home=1
+            local new_opts="$opts"
+            if [[ "$new_opts" =~ subvol= ]] || [[ "$new_opts" =~ subvolid= ]]; then
+                new_opts="$(echo "$new_opts" | sed -E 's/(subvol|subvolid)=[^,]*/subvol=@home/g')"
+            else
+                new_opts="${new_opts},subvol=@home"
+            fi
+            new_opts="$(echo "$new_opts" | sed -E -e 's/,,+/,/g' -e 's/^,//' -e 's/,$//')"
+            spec="${root_id:-$spec}"
+            printf "%s\t%s\t%s\t%s\t%s\t%s\n" "$spec" "$mnt" "$type" "$new_opts" "${freq:-0}" "${pass:-0}" >> "$tmp_fstab"
+        else
+            echo "$line" >> "$tmp_fstab"
+        fi
+    done < "$fstab_file"
+
+    # If home was not present in fstab and root was found/specified, add /home entry
+    if [[ "$found_home" -eq 0 && ( "$found_root" -eq 1 || -n "$root_spec" ) ]]; then
+        local home_opts="${root_opts/subvol=@/subvol=@home}"
+        if [[ "$home_opts" == "$root_opts" ]]; then
+            home_opts="defaults,subvol=@home"
+        fi
+        printf "%s\t%s\t%s\t%s\t%s\t%s\n" "$root_spec" "/home" "btrfs" "$home_opts" "0" "0" >> "$tmp_fstab"
+    fi
+
+    if ! cat "$tmp_fstab" > "$fstab_file" 2>/dev/null; then
+        log_warn "Could not write to $fstab_file (permission denied)."
+    fi
+    rm -f "$tmp_fstab"
+}
+
+# Main function to check and configure Btrfs subvolumes for root and home
+check_and_setup_btrfs_subvolumes() {
+    if ! is_root_btrfs; then
+        local fstype
+        fstype="$(findmnt -n -o FSTYPE / 2>/dev/null || echo "unknown")"
+        log_info "Root filesystem is not Btrfs ($fstype). Skipping Btrfs subvolume migration."
+        return 0
+    fi
+
+    log_info "Btrfs root filesystem detected."
+
+    if is_root_subvolume_configured; then
+        local fsroot
+        fsroot="$(findmnt -n -o FSROOT / 2>/dev/null || true)"
+        log_success "Root filesystem is already running inside subvolume '$fsroot'."
+        return 0
+    fi
+
+    # Ensure btrfs utility is available
+    if ! command_exists btrfs; then
+        log_info "Installing btrfs-progs..."
+        DEBIAN_FRONTEND=noninteractive apt-get update -y >/dev/null 2>&1 || true
+        DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends btrfs-progs || {
+            log_error "btrfs-progs could not be installed."
+            return 1
+        }
+    fi
+
+    local root_dev root_uuid
+    root_dev="$(get_root_btrfs_device)"
+    root_uuid="$(get_root_btrfs_uuid)"
+
+    if [[ -z "$root_dev" ]]; then
+        log_warn "Could not determine root block device for Btrfs. Skipping migration."
+        return 0
+    fi
+
+    local root_fstab_id
+    if [[ -n "$root_uuid" ]]; then
+        root_fstab_id="UUID=$root_uuid"
+    else
+        root_fstab_id="$root_dev"
+    fi
+
+    log_step "Btrfs Migration: Creating subvolumes '@' and '@home'..."
+
+    local tmp_mnt
+    tmp_mnt="$(mktemp -d /tmp/btrfs-toplevel.XXXXXX)"
+
+    # Trap to safely unmount and remove temporary mountpoint
+    cleanup_tmp_mnt() {
+        if [[ -d "$tmp_mnt" ]]; then
+            if mountpoint -q "$tmp_mnt"; then
+                umount "$tmp_mnt" 2>/dev/null || true
+            fi
+            rm -rf "$tmp_mnt"
+        fi
+    }
+
+    # Mount top-level btrfs root (subvolid=5)
+    if ! mount -t btrfs -o subvolid=5 "$root_dev" "$tmp_mnt"; then
+        log_error "Failed to mount top-level Btrfs volume on $tmp_mnt."
+        rm -rf "$tmp_mnt"
+        return 1
+    fi
+
+    # 1. Create or snapshot '@' subvolume for root
+    if [[ ! -d "$tmp_mnt/@" ]]; then
+        log_info "Creating snapshot of top-level filesystem into '@' subvolume..."
+        btrfs subvolume snapshot "$tmp_mnt" "$tmp_mnt/@"
+        log_success "Created '@' subvolume snapshot."
+    else
+        log_info "'@' subvolume already exists in top-level Btrfs tree."
+    fi
+
+    # 2. Create '@home' subvolume if /home is on the same volume
+    if ! is_home_separate_filesystem; then
+        if [[ ! -d "$tmp_mnt/@home" ]]; then
+            log_info "Creating '@home' subvolume..."
+            btrfs subvolume create "$tmp_mnt/@home"
+            log_success "Created '@home' subvolume."
+
+            # Move existing home data into @home
+            if [[ -d "$tmp_mnt/@/home" && "$(ls -A "$tmp_mnt/@/home" 2>/dev/null)" ]]; then
+                log_info "Moving existing /home data to '@home' subvolume..."
+                cp -a --reflink=auto "$tmp_mnt/@/home/." "$tmp_mnt/@home/"
+                # Clean up the directory inside @/home so it acts as an empty mountpoint
+                rm -rf "$tmp_mnt/@/home"/* "$tmp_mnt/@/home"/.[!.]* "$tmp_mnt/@/home"/..?* 2>/dev/null || true
+                chmod 755 "$tmp_mnt/@/home" 2>/dev/null || true
+                chown root:root "$tmp_mnt/@/home" 2>/dev/null || true
+                log_success "Moved /home data to '@home' subvolume."
+            fi
+        else
+            log_info "'@home' subvolume already exists in top-level Btrfs tree."
+        fi
+    else
+        log_info "/home is mounted on a separate filesystem. Skipping '@home' subvolume creation."
+    fi
+
+    # 3. Set default subvolume to '@'
+    local subvol_at_id
+    subvol_at_id="$(btrfs subvolume list "$tmp_mnt" 2>/dev/null | awk '$NF == "@" {print $2}' | tail -n1)"
+    if [[ -n "$subvol_at_id" ]]; then
+        btrfs subvolume set-default "$subvol_at_id" "$tmp_mnt"
+        log_success "Set default Btrfs subvolume to '@' (ID: $subvol_at_id)."
+    fi
+
+    # 4. Update /etc/fstab (and the snapshotted @/etc/fstab)
+    log_info "Updating /etc/fstab entries for '@' and '@home'..."
+    update_btrfs_fstab "/etc/fstab" "$root_fstab_id"
+    if [[ -f "$tmp_mnt/@/etc/fstab" ]]; then
+        update_btrfs_fstab "$tmp_mnt/@/etc/fstab" "$root_fstab_id"
+    fi
+    log_success "Updated /etc/fstab with subvolume mount options."
+
+    # 5. Mount '@home' at /home for the current live session if not already mounted
+    if ! is_home_separate_filesystem; then
+        if ! findmnt /home >/dev/null 2>&1; then
+            log_info "Mounting '@home' subvolume at /home for current setup session..."
+            mount -t btrfs -o subvol=@home "$root_dev" /home || log_warn "Could not mount @home at /home live."
+        fi
+    fi
+
+    # Clean up temporary top-level mount
+    cleanup_tmp_mnt
+
+    log_success "Btrfs subvolume setup and migration completed successfully."
+}

lib/utils.sh

@@ -250,6 +250,10 @@ run_as_target_user() {
     fi
 }
 
+run_as_user() {
+    run_as_target_user "$@"
+}
+
 # Create a safe temporary directory with auto-cleanup
 create_temp_dir() {
     local prefix="${1:-setup-temp}"
@@ -265,7 +269,14 @@ backup_file_or_dir() {
     timestamp="$(date +%Y%m%d_%H%M%S)"
     if [[ -e "$target" ]]; then
         local backup_path="${target}.backup_${timestamp}"
-        cp -r "$target" "$backup_path"
+        if cp -r "$target" "$backup_path" 2>/dev/null; then
             log_info "Created backup: $backup_path"
+        else
+            log_warn "Could not create backup of $target (permission denied)."
+        fi
     fi
 }
+
+backup_file() {
+    backup_file_or_dir "$@"
+}

setup.sh

@@ -10,6 +10,7 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 # Source Libraries & Config
 source "$SCRIPT_DIR/lib/utils.sh"
 source "$SCRIPT_DIR/lib/apt.sh"
+source "$SCRIPT_DIR/lib/btrfs.sh"
 source "$SCRIPT_DIR/lib/tui.sh"
 
 if [[ -f "$SCRIPT_DIR/config/setup.conf" ]]; then

stages/00-preflight.sh

@@ -7,6 +7,7 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 source "$SCRIPT_DIR/lib/utils.sh"
+source "$SCRIPT_DIR/lib/btrfs.sh"
 
 setup_err_trap
 
@@ -67,4 +68,8 @@ else
     log_success "Sufficient disk space available ($(( AVAILABLE_KB / 1024 / 1024 )) GB free)."
 fi
 
+# 6. Check & Setup Btrfs Subvolumes (@, @home)
+log_substep "Checking Btrfs root volume & subvolume layout..."
+check_and_setup_btrfs_subvolumes
+
 log_success "Stage 00: Pre-flight checks passed successfully."