--- ./init	2018-04-18 20:55:09.661574000 +0200
+++ ./init.new	2021-02-10 00:23:26.448715585 +0100
@@ -76,7 +76,12 @@
 INITRD=$(cat /initrd-name)
 ROOTDEV=$(cat /rootdev)
 ROOTFS=$(cat /rootfs)
-LUKSDEV=$(cat /luksdev)
+if grep -q : luksdev; then
+  LUKSDEV=$(cat /luksdev|cut -d: -f1)
+  LUKSNAME=$(cat /luksdev|cut -d: -f2)
+else
+  LUKSDEV=$(cat /luksdev)
+fi
 LUKSTRIM=$(cat /lukstrim 2>/dev/null)
 LUKSKEY=$(cat /lukskey)
 RESUMEDEV=$(cat /resumedev)
@@ -137,6 +142,12 @@
     ;;
   esac
 done
+# If GRUB unlocked the LUKS device it sends a command line like:
+# BOOT_IMAGE=/boot/<file name of the initrd> root=/dev/mapper/<name>
+# In this case we use <name> as last argument of "cryptsetup luksOpen"
+# and mount  /dev/mapper/<name> on /mnt
+
+echo $root | grep -q /dev/mapper && LUKSNAME=$(basename $root)
 
 # If udevd is available, use it to generate block devices
 # else use mdev to read sysfs and generate the needed devices 
@@ -193,8 +204,9 @@
   # partitions or mdadm arrays.
   # Unavailable devices such as LVM Logical Volumes will need to be
   # deferred until they become available after the vgscan.
-
-  if [ -x /sbin/cryptsetup ]; then
+  
+  [ "$LUKSKEY" ] && ! echo "$LUKSKEY" |grep -q "^/dev" && KEYININITRD="y"
+  if [ -x /sbin/cryptsetup ] && [ ! "$KEYININITRD" ] ; then
 
     # Determine if we have to use a LUKS keyfile:
     if [ ! -z "$LUKSKEY" ]; then
@@ -229,6 +241,8 @@
           CRYPTDEV="luks$(basename $LUKSDEV)"
         elif [ "x$ROOTDEV" = "x$(basename $ROOTDEV)" ]; then
           CRYPTDEV="$ROOTDEV"
+        elif [ "$LUKSNAME" ]; then
+          CRYPTDEV="$LUKSNAME"
         else
           CRYPTDEV="luks$(basename $LUKSDEV)"
         fi
@@ -252,6 +266,12 @@
     done
   fi
 
+  if [ -x /sbin/cryptsetup ] && [ "$KEYININITRD" ] ; then
+    [ ! "$LUKSNAME" ] && LUKSNAME=cryptroot
+    echo "Unlocking the root partition."
+    cryptsetup open --key-file "$LUKSKEY" "$LUKSDEV" "$LUKSNAME"
+  fi 
+
   # Initialize LVM:
   if [ -x /sbin/vgchange ]; then
     mkdir -p /var/lock/lvm	# this avoids useless warnings