From a605ac10973b145e1121c858d3955bd4ef7103b1 Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Wed, 20 Apr 2016 15:37:48 -0400
Subject: btrfs-based encrypted persistent root

This replaces the old LVM code with btrfs-based code.
---
 old-school/lvm-create.sh | 209 ++++-------------------------------------------
 1 file changed, 15 insertions(+), 194 deletions(-)

(limited to 'old-school')

diff --git a/old-school/lvm-create.sh b/old-school/lvm-create.sh
index 22016f5..ba79e0c 100644
--- a/old-school/lvm-create.sh
+++ b/old-school/lvm-create.sh
@@ -4,12 +4,6 @@
 
 losetup() { /sbin/losetup "$@"; }
 
-lvm()
-{
-  # get rid of warnings from lvm because we are holding open these fds
-  command lvm "$@" 3>&- 4>&-
-}
-
 luks_secret()
 {
   local parms=$-; # this junk keeps set -x from being too annoying
@@ -33,11 +27,6 @@ mount_squashfs_images()
   bootdone squashfs-root
 }
 
-lv_exists()
-{
-  [ -n "$1" ] && lvm lvs "$1" >/dev/null 2>&1
-}
-
 floor4()
 {
   # Negatives round up, but aren't used.
@@ -51,30 +40,6 @@ ceil4()
   printf '%d\n' "$x"
 }
 
-vgfree_megs()
-{
-  local vg="$1" out
-  out=$(lvm vgs -o pv_free --noheadings --nosuffix --units m "$vg") || return
-  echo ${out%.*}
-}
-
-init_samizdat_lvs()
-{
-  local megs_free cdrom_dev cdrom_sectors cdrom_megs root_megs
-  megs_free=$(vgfree_megs samizdat) || return
-  cdrom_dev="$(mountpoint_to_dev /cdrom)" || return
-  cdrom_sectors=$(blockdev --getsz "$cdrom_dev") || return
-  cdrom_megs=$(ceil4 $(( cdrom_sectors / 2048 )))
-  root_megs=$(floor4 $(( megs_free - cdrom_megs )))
-
-  if [ $root_megs -le 0 ]; then # No room for cdrom mirror.  Oh well, charge forward.
-    root_megs=$megs_free
-  fi
-
-  lvm lvcreate -Z n -L ${root_megs}m -n root samizdat || return
-  $ROOT_MKFS_CMD /dev/mapper/samizdat-root || return
-}
-
 mount_aufs_branches()
 {
   local new="$1"
@@ -95,20 +60,24 @@ init_samizdat()
 {
   local imgfile="$1" megs="$2" keyfile="$3" dev
 
-  init_samizdat_vg "$imgfile" "$megs" "$keyfile" || return
-  init_samizdat_lvs || return
+  init_samizdat_blockdev "$imgfile" "$megs" "$keyfile" || return
+  local blockdev=/dev/mapper/samizdatcrypt
 
-  mount_aufs_branches new
+  mount -t btrfs -o subvol=ROOT /cdrom/live/filesystem.btrfs /root || return
+  btrfs device add "$blockdev" /root || return
+  mount -o rw,remount /root || return
+  bootdone root-mounted
 }
 
 open_samizdat()
 {
-  open_samizdat_vg "$@" || return
-
-  lvs=$(lvm lvs --separator / samizdat -o vg_name,lv_name --noheadings) || return
-  lvm lvchange -ay $lvs || return
-
-  mount_aufs_branches
+  open_samizdat_blockdev "$@" || return
+  local blockdev=/dev/mapper/samizdatcrypt
+  losetup -f /cdrom/live/filesystem.btrfs || return
+  modprobe btrfs || return
+  btrfs device scan || return
+  mount -t btrfs -o subvol=ROOT "$blockdev" /root || return
+  bootdone root-mounted
 }
 
 init_samizdat_lodev()
@@ -119,7 +88,7 @@ init_samizdat_lodev()
   echo "$dev"
 }
 
-open_samizdat_vg()
+open_samizdat_blockdev()
 {
   local imgfile="$1" keyfile="$2" dev
   local cryptname=samizdatcrypt
@@ -134,7 +103,7 @@ open_samizdat_vg()
 
 }
 
-init_samizdat_vg()
+init_samizdat_blockdev()
 {
   local imgfile="$1" megs="$2" keyfile="$3" dev
   local cryptname=samizdatcrypt
@@ -151,21 +120,6 @@ init_samizdat_vg()
   luks_secret | cryptsetup --key-file - luksOpen "$dev" "$cryptname" || return
 
   [ -b /dev/mapper/"$cryptname" ] || return
-
-  lvm pvcreate /dev/mapper/"$cryptname" || return
-  lvm vgcreate samizdat /dev/mapper/"$cryptname"
-}
-
-grow_samizdat_vg_free()
-{
-  # Grow the samizdat VG sufficiently to ensure it has at least $want_free_megs free.
-
-  local want_free_megs=$(ceil4 "$1") free_megs
-  free_megs=$(vgfree_megs samizdat) || return
-
-  if [ "$free_megs" -lt "$want_free_megs" ]; then
-    grow_samizdat_vg $((want_free_megs - free_megs)) || return
-  fi
 }
 
 majmin()
@@ -176,22 +130,6 @@ majmin()
   printf '%d:%d\n' 0x$major 0x$minor
 }
 
-vg_to_pv()
-{
-  lvm vgs "$1" -o devices --noheadings |
-  (
-    found= multidev=
-    while read dev; do
-      dev=${dev%(*}
-      if [ "$found" -a "$found" != "$dev" ]; then
-	exit 1
-      fi
-      found=$dev
-    done
-    readlink -f "$found"
-  )
-}
-
 cryptdev_to_dev()
 {
   local dev="$1" majmin
@@ -212,29 +150,6 @@ cryptdev_to_backing_file()
   printf '%s\n' "$result"
 }
 
-samizdat_backing_file()
-{
-  local pv
-  pv=$(vg_to_pv samizdat) && [ "$pv" ] || return
-  cryptdev_to_backing_file "$pv"
-}
-
-grow_samizdat_lv()
-{
-  # Increase the size of the specified LV by $megs MB, creating the LV and resizing the VG as necessary.
-
-  local lv_name="$1" megs="$2" stat imgfile freemegs
-  imgfile=$(samizdat_backing_file) || return
-
-  if lv_exists samizdat/"$lv_name"; then
-    grow_samizdat_vg_free "$megs" || return
-    lvm lvresize -r -L +${megs}m samizdat/"$lv_name" || return
-  else
-    grow_samizdat_vg_free "$megs" || return
-    lvm lvcreate -Z n -L ${megs}m -n "$lv_name" samizdat || return
-  fi
-}
-
 lodev_to_file()
 {
   local result majmin dev="$1"
@@ -243,41 +158,6 @@ lodev_to_file()
   printf '%s' "$result"
 }
 
-grow_samizdat_vg()
-{
-  # Increase the size of the samizdat VG by $megs MB, resizing the backing file as necessary.
-
-  local megs="$1" cryptdev dev imgfile stat
-  cryptdev=$(vg_to_pv samizdat)
-  dev=$(cryptdev_to_dev "$cryptdev") || return
-  [ -b "$dev" ] || return
-
-  if [ "$(stat -c '%t' "$dev")" = 7 ]; then # this is a loop device
-
-    imgfile=$(lodev_to_file "$dev") || return
-    stat="$(stat -c 'local du=$((%B*%b)) sz=%s' "$imgfile")" || return
-    eval "$stat"
-    stat=$(stat -f -c 'local df=$((%f*%S))' "$imgfile") || return
-    eval "$stat"
-
-    local min_free_space=30
-    if [ $(( df - megs*1024*1024 - sz + du )) -le $((min_free_space * 1024 * 1024)) ]; then
-      echo 'grow_samizdat_vg: Not enough disk space!' >&2
-      return -1
-    fi
-
-    truncate -cs +${megs}M "$imgfile" || return
-    losetup -c "$dev" || return
-    cryptsetup resize "$cryptdev" || return
-    lvm pvresize "$cryptdev" || return
-
-  else
-    echo 'grow_samizdat_vg: Unimplemented!' >&2
-    return 1
-
-  fi
-}
-
 mountpoint_to_dev()
 {
   local wantmp="$1" dev mp rest
@@ -298,65 +178,6 @@ get_cdrom_sizelimit()
   fi
 }
 
-mirror_cdrom()
-{
-  local md_num=55 dev mp rest cdrom_dev sectors
-  cdrom_dev="$(mountpoint_to_dev /cdrom)" || return
-
-  local lv_name=samizdat/cdrom
-  local lv_dev=/dev/mapper/samizdat-cdrom
-  local md_name=/dev/md$md_num
-
-  if [ -b $md_name ]; then
-    echo "RAID device already exists: '$md_name'; try removing (mdadm -S $md_name) and retry" >&2
-    return 1
-  fi
-
-  if lv_exists $lv_name.tmp; then
-    lvm lvchange --available n $lv_name.tmp && lvm lvremove $lv_name.tmp || return
-  fi
-
-  if lv_exists $lv_name; then
-    umount /cdrom || return
-    mount -r "$lv_dev" /cdrom
-    return
-  fi
-
-  umount /cdrom || return
-
-  sectors=$(blockdev --getsz "$cdrom_dev") || return
-  grow_samizdat_lv ${lv_name#samizdat/}.tmp $((sectors / 2 / 1024 + 1)) || return
-
-  # In order to trick mdadm into accepting a read-only device, we need
-  # to create a (read-write) loopback device.
-
-  # Furthermore, in order to deal with block device errors caused by
-  # TAO "run-out blocks" we may need to discard the last two 2048-byte
-  # sectors.
-
-  local cdrom_loopdev sizelimit
-  cdrom_loopdev=$(losetup -f) || return
-  sizelimit=$(get_cdrom_sizelimit "$cdrom_dev")
-
-  # Apparently loopdev sizelimit is not respected by linux md.  Nor
-  # blockdev --getsz.  Does it even work?  Anyway, although this is used
-  # here redundantly, 'mdadm --size' is used as well.
-  /sbin/losetup ${sizelimit:+--sizelimit=$sizelimit} "$cdrom_loopdev" "$cdrom_dev" || return
-
-  mdadm --build $md_name ${sizelimit:+--size=$((sizelimit / 1024))} \
-    --level=1 --raid-devices=1 --force --write-mostly "$cdrom_loopdev" || return
-  mdadm -D $md_name >&2
-  mdadm --add $md_name $lv_dev.tmp
-  mdadm -D $md_name >&2
-  mdadm --grow $md_name -n 2
-  mdadm -D $md_name >&2
-
-  mount -r $md_name /cdrom || { mount -r "$cdrom_dev" /cdrom; return 1; }
-
-  chpst -P samizdat-cdrom-copy "$md_name" "$lv_name" "$lv_dev" "$cdrom_loopdev" "$cdrom_dev" &
-  echo "[$$] Launched RAID monitor with pid $!." >&2
-}
-
 init_gpg()
 {
   bootwait samizdat-cdrom
-- 
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