zfsbootmenu: warn when canmount=on is set for root dataset

zfsbootmenu/lib/zfsbootmenu-lib.sh

@@ -546,7 +546,7 @@ get_sort_key() {
 # returns: 0 iff at least one valid BE was found
 
 populate_be_list() {
- local be_list fs mnt active candidates ret sort_key
+ local be_list fs canmount mnt active candidates ret sort_key
 
  be_list="${1}"
  if [ -z "${be_list}" ]; then
@@ -561,7 +561,7 @@ populate_be_list() {
  : > "${be_list}"
 
  # Find valid BEs
- while IFS=$'\t' read -r fs mnt active; do
+ while IFS=$'\t' read -r fs canmount mnt active; do
  if [ "${mnt}" = "/" ]; then
  # When mountpoint=/, BE is a candidate unless org.zfsbootmenu:active=off
  [ "${active}" = "off" ] && continue
@@ -577,8 +577,13 @@ populate_be_list() {
  continue
  fi
 
+ # root datasets should never be automatically mounted by the boot environment
+ if [ "${canmount}" = "on" ]; then
+ zwarn "canmount=on set for '${fs}', should be canmount=noauto"
+ fi
+
  candidates+=( "${fs}" )
- done <<< "$(zfs list -H -o name,mountpoint,org.zfsbootmenu:active -S "${sort_key}")"
+ done <<< "$(zfs list -H -o name,canmount,mountpoint,org.zfsbootmenu:active -S "${sort_key}")"
 
  # put bootfs on the end, so it is shown first with --tac
  [ -n "${BOOTFS}" ] && candidates+=( "${BOOTFS}" )