Comment 6 for bug 1247905

I have made some implovement to /usr/sbin/grub-probe-overlay code.

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#!/bin/sh

ARGS=

for ARG in $@; do
 if [ "${ARG%%[!/]*}" = "/" ]; then

  OPTIONS=

  path="$ARG"
  while true; do
   if FSTYPE=$( findmnt -n -o FSTYPE "$path" ); then
    if [ "$FSTYPE" = "overlay" ]; then
  OPTIONS=$(findmnt -n -o OPTIONS "$path")
  break
 else
  break
    fi
   fi
   if [ "$path" = "/" ]; then break; fi
   path=$(dirname "$path")
  done

  if LOWERDIR=$(echo "$OPTIONS" | grep -m 1 -oP 'lowerdir=\K[^,]+'); then
   #echo "[DEBUG] Overlay filesystem detected ${ARG} --> ${LOWERDIR}${ARG%*/}" 1>&2
   ARG="${LOWERDIR}${ARG%*/}"
  fi
 fi
 ARGS="$ARGS $ARG"
done

grub-probe-default $ARGS

exit $?
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