2 files changed, 293 insertions, 0 deletions

diff --git a/notes/btrfs-test.sh b/notes/btrfs-test.sh
new file mode 100644
index 0000000..62cab9a
--- /dev/null
+++ b/notes/btrfs-test.sh
@@ -0,0 +1,282 @@
+#!/bin/sh
+
+. ./var.sh
+. ./btrfs-functions.sh
+
+create_image()
+{
+    $(ARGS_NE megs filename)
+    [ ! -e "$filename" ] || return
+    truncate -s "$megs"M "$filename"
+}
+
+make_seed_fs()
+{
+    $(ARGS_NE input_dir img)
+    local mountpoint dev seed_subvol root_subvol
+
+    mountpoint=$img.mnt
+    mkdir "$mountpoint"                    || die 'mkdir failed'
+    dev=$(lodev "$img")                    || die 'lodev failed'
+    mkfs.btrfs "$dev"                      || die 'mkfs failed'
+    mount "$dev" "$mountpoint"             || die 'mount failed'
+
+    seed_subvol=$mountpoint/SEED
+    root_subvol=$mountpoint/ROOT
+    btrfs subvolume create "$root_subvol"                     || die
+    rsync -aP "$input_dir"/ "$root_subvol"/                   || die 'rsync failed'
+    btrfs subvolume snapshot -r "$root_subvol" "$seed_subvol" || die
+    btrfs_subvolume_set_default "$root_subvol" || die
+
+    umount "$mountpoint"                   || die 'umount failed'
+    rmdir "$mountpoint"
+    btrfstune -S 1 "$dev"                  || die 'btrfstune failed'
+    unlodev "$dev"
+}
+
+btrfs_subvolume_set_default()
+{
+    $(ARGS_NE path)
+    local subvol_id
+    subvol_id=$(btrfs_show_subvolume_id "$path")       || return
+    btrfs subvolume set-default "$subvol_id" "$path"
+}
+
+loop_is_attached()
+{
+    [ "$(losetup -l  "$1" -O BACK-FILE -n 2>/dev/null)" ]
+}
+
+lodev() { lodev_helper false "$@"; }
+lodev_readonly() { lodev_helper true "$@"; }
+
+lodev_helper()
+{
+    $(ARGS_NE readonly img)
+    local link b dev opt_ro
+    link=$img.b
+    if $readonly; then
+        opt_ro=-r
+    else
+        opt_ro=
+    fi
+    if [ -L "$link" ]; then
+        b="$(readlink "$link")"
+        loop_is_attached "$b" || losetup $opt_ro "$b" "$img" || return
+    else
+        dev=$(unused_dev) || return
+        losetup $opt_ro "$dev" "$img" || return
+        ln -sf "$dev" "$img".b || return
+    fi >/dev/null
+    printf '%s\n' $link
+}
+
+unused_dev()
+{
+    local do_not_use f d no
+    do_not_use=$(for f in *.b; do [ -L "$f" ] || continue; readlink $f; done)
+    for n in $(seq 10 20); do
+        d=/dev/loop$n
+        for no in $do_not_use; do
+            [ "$d" != "$no" ] || continue 2
+        done
+        echo $d
+        return
+    done
+}
+
+unlodev()
+{
+    $(ARGS_NE link)
+    [ -L "$link" ] || return
+    losetup -d "$(readlink "$link")" # && rm -f "$link"
+}
+
+plant_seed()
+{
+    $(ARGS_NE seed_img overlay_img mountpoint)
+    local overlay_dev seed_dev
+
+    overlay_dev=$(lodev "$overlay_img")             || die 'lodev failed'
+    seed_dev=$(lodev_readonly "$seed_img")          || die 'lodev failed'
+
+    mount "$seed_dev" "$mountpoint"                 || die 'mount failed'
+
+    btrfs device add "$overlay_dev" "$mountpoint"   || die 'btrfs-device-add failed'
+    mount -o rw,remount "$mountpoint"               || die 'remount failed'
+    btrfs device delete "$seed_dev" "$mountpoint"   || die 'btrfs-device-delete failed'
+
+    unlodev "$seed_dev"
+
+    umount "$mountpoint"
+    unlodev "$overlay_dev"
+}
+
+generate_seed_helper()
+{
+    $(ARGS_NE seed_layer keep_old_seeds size seed_img snapshot_mountpoint overlay_img_output)
+    local mountpoint overlay_dev seed_dev snapshot_default
+    mountpoint=${overlay_img_output}.mnt
+
+    mountpoint -q "$snapshot_mountpoint" || die
+    [ -d "$mountpoint" ]  || mkdir "$mountpoint" || die
+
+    filemaker "$overlay_img_output" create_image "$size" || die
+
+    overlay_dev=$(lodev "$overlay_img_output") || die
+    seed_dev=$(lodev_read_only "$seed_img") || die
+
+    mount -o subvol=/ "$seed_dev" "$mountpoint" || die
+    btrfs device add "$overlay_dev" "$mountpoint" || die
+    mount -o rw,remount "$mountpoint" || die
+
+    snapshot_default=$(btrfs_show_default_path "$snapshot_mountpoint") || die
+
+    push_simple "$snapshot_mountpoint"/SEED_NEW "$snapshot_mountpoint"/SEED "$snapshot_default" "$mountpoint"
+
+    if $keep_old_seeds; then
+        sex mv -T --backup=numbered "$mountpoint"/SEED_NEW "$mountpoint"/SEED || die
+    else
+        btrfs subvolume delete "$mountpoint"/SEED || die
+        sex mv "$mountpoint"/SEED_NEW "$mountpoint"/SEED || die
+    fi
+
+    if ! $seed_layer; then
+        btrfs device remove "$seed_dev" "$mountpoint" || die
+    fi
+
+    umount "$mountpoint" || die
+    rmdir "$mountpoint"
+
+    btrfstune -S 1 "$overlay_img_output"                  || die 'btrfstune failed'
+}
+
+generate_seed_overlay() # NB. uses non-local variables set in <..>_helper
+{
+    generate_seed_helper true true "$@"
+}
+
+regenerate_toplevel_seed()
+{
+    generate_seed_helper false true "$@"
+}
+
+regenerate_from_master()
+{
+    regenerate_toplevel_seed 256 seed.img master overlay.img
+    remove_image seed.img || die
+    mv overlay.img seed.img || die
+    mv overlay.img.b seed.img.b || die
+}
+
+plant_seed_mount()
+{
+    plant_seed "$1" "$2" "$3"
+    mount "$(lodev "$2")" "$3"
+}
+
+plant_seed_mount_rootvol()
+{
+    plant_seed "$1" "$2" "$3"
+    mount -o subvol=/ "$(lodev "$2")" "$3"
+}
+
+remove_image()
+{
+    unlodev "$1.b"
+    rm -f "$1" "$1.b"
+}
+
+IMAGES='master.img slave.img seed.img overlay.img'
+MNTPOINTS='master slave/mnt slave seed.img.mnt overlay.img.mnt'
+
+mounter()
+{
+    $(ARGS_NE mp)
+    shift
+    mountpoint -q "$mp" && return
+    mkdir "$mp" 2>/dev/null
+    "$@" "$mp"
+}
+
+filemaker()
+{
+    $(ARGS_NE f)
+    shift
+    [ -f "$f" ] && return
+    ! [ -e "$f" ] || return
+    "$@" "$f"
+}
+
+in_dir()
+{
+    (set -e
+     cd "$1"
+     shift
+     "$@")
+}
+
+pull()
+{
+    $(ARGS_NE mnt src dst)
+    local src_subvol
+    src_subvol=$(btrfs_show_default_path "$src") || die
+
+    die 'unimplemented'
+}
+
+push_slave()
+{
+    local mnt img img_dev
+    mnt=slave/mnt
+    img=slave.img
+    mkdir "$mnt" 2>/dev/null
+    img_dev=$(lodev "$img") || die
+    mounter "$mnt" mount -o subvol=/ "$img_dev" || die
+
+    push "$mnt" slave master
+    umount "$mnt"
+    losetup -D
+}
+
+main()
+{
+    local img
+
+    mkdir inp
+    touch inp/file.txt
+
+    for img in $IMAGES; do
+        filemaker $img create_image 256 || die            # Note: btrfs kernel task hangs if image is too small!
+    done
+
+    make_seed_fs inp seed.img || die
+
+    mounter slave   plant_seed_mount         seed.img slave.img
+    mounter master  plant_seed_mount_rootvol seed.img master.img
+}
+
+cleanup()
+{
+    local img m
+
+    for img in $IMAGES; do
+        remove_image "$img"
+    done
+    for m in $MNTPOINTS; do
+        umount "$m" 2>/dev/null
+        rmdir "$m" 2>/dev/null
+    done
+    losetup -D 2>/dev/null
+    true
+}
+
+case "$1" in
+    clean|cleanup) cleanup ;;
+    testclean) main; cleanup ;;
+    cleantest) cleanup; main ;;
+    push) push_slave ;;
+    regen) regenerate_from_master ;;
+    '') main ;;
+    *) die "Unknown command: $1" ;;
+esac
diff --git a/notes/xorriso-patch.sh b/notes/xorriso-patch.sh
new file mode 100644
index 0000000..47a9934
--- /dev/null
+++ b/notes/xorriso-patch.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+exit
+# This kept the ISO bootable:
+
+xorriso -drive_class clear_list all \
+        -indev debian-live-8.4.0-amd64-standard.iso \
+        -outdev test3.iso \
+        -rm_r live install pool -- \
+        -pathspecs on \
+        -add live=isolinux/live/ isolinux/pxelinux.* isolinux/*.cfg -- \
+        -boot_image isolinux patch