add support for booting snapshots on LUKS encrypted disk (#333)

* add support for booting snapshots on LUKS encrypted disk

* documentation for booting from LUKS encrypted devices

* better detecting cryptdevice UUID

41_snapshots-btrfs

@@ -122,6 +122,25 @@ boot_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "",
 boot_hs=$(${grub_probe} --device ${boot_device} --target="hints_string" 2>/dev/null) # hints string
 boot_fs=$(${grub_probe} --device ${boot_device} --target="fs" 2>/dev/null) # Type filesystem of boot device
 
+# Enable LUKS encrypted devices support
+case "$(echo "$GRUB_BTRFS_ENABLE_CRYPTODISK" | tr '[:upper:]' '[:lower:]')" in
+    true)
+            list_insmods=()
+            list_insmods+=("insmod gzio")
+            list_insmods+=("insmod part_gpt")
+            list_insmods+=("insmod cryptodisk")
+            list_insmods+=("insmod luks")
+            list_insmods+=("insmod gcry_rijndael")
+            list_insmods+=("insmod gcry_rijndael")
+            list_insmods+=("insmod gcry_sha256")
+            list_insmods+=("insmod ${boot_fs}")
+            list_insmods+=("cryptomount -u $(echo $GRUB_CMDLINE_LINUX_DEFAULT | grep -o -P '(?<=cryptdevice=UUID=).*(?=:cryptdev)')")
+            ;;
+    *)
+            list_insmods=("insmod ${boot_fs}")
+            ;;
+esac
+
 ## Parameters passed to the kernel
 kernel_parameters="$GRUB_CMDLINE_LINUX $GRUB_CMDLINE_LINUX_DEFAULT $GRUB_BTRFS_SNAPSHOT_KERNEL_PARAMETERS"
 ## Mount point location
@@ -218,8 +237,12 @@ make_menu_entries()
         if [ x\$feature_all_video_module = xy ]; then
         insmod all_video
         fi
-        set gfxpayload=keep
-        insmod ${boot_fs}
+        set gfxpayload=keep"
+        for j in "${insmods[@]}"; do
+            entry "\
+        ${j}"
+        done
+        entry "\
         if [ x\$feature_platform_search_hint = xy ]; then
             search --no-floppy --fs-uuid  --set=root ${boot_hs} ${boot_uuid}
         else
@@ -541,6 +564,7 @@ boot_bounded()
         detect_rootflags
         title_format
         boot_dir_root_grub="$(make_system_path_relative_to_its_root "${boot_dir}")" # convert "boot_directory" to root of GRUB (e.g /boot become /)
+        insmods=("${list_insmods[@]##*"/"}")
         make_menu_entries
         # show snapshot found during run "grub-mkconfig"
         if [ "${GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND:-"true"}" = "true" ]; then