Add more robust removal of LVM on target

Should prevent strange failures to recreate LVM if a previous one
existed and no block zeroing is done.

templates/install.sh

@@ -552,8 +552,32 @@ else
     echo "found small disk (${blockdev_size_gbytes} < 100GB), using small partition sizes."
 fi
 
-echo -n "Disabing existing volume groups... "
-vgchange -an >&2 || true
+echo -n "Unmounting potential partitions on target device... "
+for mount in $( mount | grep "${target_disk}" | awk '{ print $3 }' | sort -r ); do
+    umount -f ${mount} >&2
+done
+echo "done."
+
+echo -n "Unmounting potential LVM logical volumes on target device... "
+for vg in $( pvscan | grep "${target_disk}" | awk '{ print $4 }' ); do
+    for mount in $( mount | grep "/${vg}" | awk '{ print $3 }' | sort -r ); do
+        umount -f ${mount} >&2
+    done
+done
+echo "done."
+
+echo -n "Disabing potential LVM volume groups on target device... "
+for vg in $( pvscan | grep "${target_disk}" | awk '{ print $4 }' ); do
+    vgchange -an ${vg} >&2 || true
+    sleep 1
+    vgchange -an ${vg} >&2
+done
+echo "done."
+
+echo -n "Removing existing LVM physical volumes... "
+for pv in $( pvcscan | grep "${target_disk}" | awk '{ print $2 }' ); do
+    yes | pvremove ${pv}
+done
 echo "done."
 
 blockcheck() {