image-ddi: Mount persistent storage from internal/rw LVM LV

2026-07-22 01:13:00 +02:00 · 2026-03-08 21:56:45 +00:00
parent 3f23aa92be
commit ea315bdb10
3 changed files with 226 additions and 0 deletions
@@ -0,0 +1,15 @@
+tmpfs		/tmp		tmpfs	mode=0755,nosuid,nodev	0	0
+tmpfs		/run		tmpfs	mode=0755,nosuid,nodev	0	0
+tmpfs		/media		tmpfs	mode=1755,nosuid,nodev	0	0
+tmpfs		/mnt/tmp	tmpfs	defaults		0	0
+
+# Locate and mount /cfg, /home, /root and /var from the internal
+# volume, wherever that is located - or, as a last resort, setup tmpfs
+# mounts at these points. Setup an ephemeral writable overlay on /etc.
+/usr/libexec/infix/mnt#	/mnt/rw	  helper	none			0	0
+
+# Optional, nice-to-have mounts
+debugfs		/sys/kernel/debug   debugfs	nofail			0	0
+tracefs		/sys/kernel/tracing tracefs	nofail			0	0
+cfgfs		/config		    configfs	nofail,noauto		0	0
+host		/mnt/host	    9p		nofail,noauto,cache=none,msize=16384	0	0
@@ -0,0 +1,211 @@
+#!/bin/sh
+# Called from /etc/fstab to ensure we have something writable mounted
+# at /cfg, /home, /root, and /var.
+#
+# In the normal case, the "rw" LV from the "internal" LVM VG is used
+# to back all persistant storage. In the event that "internal" is
+# present, but the "rw" LV is missing, one will be provisioned, along
+# with the required BTRFS subvolumes.
+#
+# In all other scenarios where the subvolumes are not available, the
+# system will fall back to temporary storage for all mount points.
+#
+# For /etc, a writable, tmpfs backed, layer is always overlayed on top
+# of the read-only contents from the OS image.
+
+set -e
+
+nm=$(basename "$0")
+need_restore=
+code=0
+
+logmsg()
+{
+    logger -k -t "$nm" -p user.crit "$@"
+}
+
+status()
+{
+    GREEN="$(printf '\033[1;32m')"
+    RED="$(printf '\033[1;31m')"
+    YELLOW="$(printf '\033[1;33m')"
+    BOLD="$(printf '\033[1m')"
+    RESET="$(printf '\033[0m')"
+
+    case $1 in
+        0) color=$GREEN; text=' OK ' ;;
+        1) color=$RED;   text='FAIL' ;;
+        2) color=$YELLOW;text='WARN' ;;
+        *) color=$YELLOW;text=' ⋯  ' ;;
+    esac
+
+    printf '%s[%s%s%s%s]%s ' "$BOLD" "$color" "$text" "$RESET" "$BOLD" "$RESET"
+}
+
+print_start()
+{
+    printf '\r\033[K%s%s' "$(status 3)" "$*" > /dev/console
+    need_restore=YES
+}
+
+print_end()
+{
+    rc=$1; shift
+    if [ $# -gt 0 ]; then
+        printf '\r\033[K%s%s\n' "$(status "$rc")" "$*" > /dev/console
+    else
+        printf '\r%s\n' "$(status "$rc")" > /dev/console
+    fi
+}
+
+# Restore Finit's original progress message so its [ OK ] appears correctly
+print_restore()
+{
+    [ "$need_restore" ] || return 0
+    print_start "Mounting filesystems from /etc/fstab"
+}
+
+# # External button or bootloader changed kernel command line
+# check_factory()
+# {
+#     if [ -f /mnt/cfg/infix/.reset ]; then
+# 	return 0;
+#     fi
+
+#     if grep -q 'finit.cond=factory-reset' /proc/cmdline; then
+# 	return 0;
+#     fi
+
+#     # Add to your br2-external to extend factory-reset check
+#     if [ ! -x /usr/libexec/infix/check-factory ]; then
+# 	return 1;
+#     fi
+
+#     /usr/libexec/infix/check-factory
+# }
+
+# factory_reset()
+# {
+#     find /sys/class/leds/ -type l -exec sh -c 'echo 100 > $0/brightness' {} \;
+#     print_start "Resetting to factory defaults."
+#     logger $opt -p user.notice -t "$nm" "Resetting to factory defaults."
+
+#     rm -rf /mnt/cfg/* /mnt/var/*
+#     sync
+
+#     logger $opt -p user.notice -t "$nm" "Factory reset complete."
+#     print_end 0 "Factory reset complete."
+#     print_restore
+# }
+
+subvols="cfg var root home"
+
+internal_rw_provision()
+{
+    print_start "Provisioning persistent storage on internal volume"
+
+    lvm lvcreate --name rw --extents 50%FREE internal || {
+	logmsg "No rw LV available, nor could it be created"
+	print_end 1
+	return 1
+    }
+
+    mkfs.btrfs -L rw /dev/internal/rw || {
+	logmsg "Could not create BTRFS on rw LV"
+	print_end 1
+	return 1
+    }
+
+    mount -t btrfs /dev/internal/rw /mnt/rw || {
+	logmsg "Failed to mount rw"
+	print_end 1
+	return 1
+    }
+
+    for subvol in $subvols; do
+	btrfs subvolume create /mnt/rw/@"$subvol" || {
+	    logmsg "Failed to create @$subvol on rw"
+	    print_end 1
+	    return 1
+	}
+    done
+
+    umount /mnt/rw || {
+	logmsg "Failed to unmount rw"
+	print_end 1
+	return 1
+    }
+
+    print_end 0
+}
+
+internal_rw_activate()
+{
+    lvm vgs internal || {
+	logmsg "No internal volume available"
+	return 1
+    }
+
+    lvm vgchange -ay internal || {
+	logmsg "Unable to bring internal volume online"
+	return 1
+    }
+
+    # The only condition under which we do BTRFS provisioning is when
+    # the LV is absent. In all other failure scenarios: fall back to
+    # tmpfs and let the user sort it out. This way we do not risk any
+    # loss of data.
+    [ -b /dev/internal/rw ] && return 0
+
+    internal_rw_provision
+}
+
+internal_rw_mount()
+{
+    internal_rw_activate || return 1
+
+    for subvol in $subvols; do
+	mount -t btrfs /dev/internal/rw /"$subvol" -o subvol=@"$subvol" || {
+	    logmsg "Failed to mount /$subvol"
+	    return 1
+	}
+    done
+}
+
+tmpfs_rw_mount()
+{
+    for subvol in $subvols; do
+	mkdir -p -m 0755 /mnt/tmp/"$subvol"
+	mount /mnt/tmp/"$subvol" /"$subvol" -o bind || {
+	    logmsg "Failed to mount temporary /$subvol"
+	    return 1
+	}
+    done
+}
+
+tmpfs_etc_mount()
+{
+    mkdir -p -m 0755 /mnt/tmp/etc/
+    tar c -C /etc . | tar x -C /mnt/tmp/etc
+    mount /mnt/tmp/etc /etc -o bind
+}
+
+exec >/mnt/tmp/mnt.log 2>&1
+
+tmpfs_etc_mount || {
+    code=1
+    logmsg "Failed to make /etc writable"
+}
+
+if ! internal_rw_mount; then
+    code=1
+    print_end 1 "Mounting persistent storage from internal volume"
+    logmsg "Internal volume not found, falling back to tmpfs"
+
+    print_start "Falling back to ephemeral tmpfs storage!"
+    tmpfs_rw_mount
+    print_end $?
+fi
+
+print_restore
+exit $code