Merge pull request #35188 from sorki/overlayfs

use overlayfs by default for netboot and iso

nixos/modules/system/boot/stage-1-init.sh

@@ -334,8 +334,10 @@ mountFS() {
 
     # Filter out x- options, which busybox doesn't do yet.
     local optionsFiltered="$(IFS=,; for i in $options; do if [ "${i:0:2}" != "x-" ]; then echo -n $i,; fi; done)"
+    # Prefix (lower|upper|work)dir with /mnt-root (overlayfs)
+    local optionsPrefixed="$( echo "$optionsFiltered" | sed -E 's#\<(lowerdir|upperdir|workdir)=#\1=/mnt-root#g' )"
 
-    echo "$device /mnt-root$mountPoint $fsType $optionsFiltered" >> /etc/fstab
+    echo "$device /mnt-root$mountPoint $fsType $optionsPrefixed" >> /etc/fstab
 
     checkFS "$device" "$fsType"
 
@@ -354,10 +356,11 @@ mountFS() {
             ;;
     esac
 
-    # Create backing directories for unionfs-fuse.
-    if [ "$fsType" = unionfs-fuse ]; then
-        for i in $(IFS=:; echo ${options##*,dirs=}); do
-            mkdir -m 0700 -p /mnt-root"${i%=*}"
+    # Create backing directories for overlayfs
+    if [ "$fsType" = overlay ]; then
+        for i in upper work; do
+             dir="$( echo "$optionsPrefixed" | grep -o "${i}dir=[^,]*" )"
+             mkdir -m 0700 -p "${dir##*=}"
         done
     fi