Using OverlayFS instead of AUFS.

Newer kernels do not support AUFS by default.
OverlayFS however is widely supported.
Same functionality can be archieved.

1 files changed, 33 insertions, 13 deletions

diff --git a/squashfu b/squashfu
index cc91e33..48f5df7 100755
--- a/squashfu
+++ b/squashfu
@@ -95,33 +95,53 @@ mount_squash () {
 }
 
 mount_union_with_bins () {
-# Arguments: numbers of bins to be mounted (variable number)
-# Returns: 0 on successful mount, non-zero on failure
-  info "Mounting union"
+  # Args: Nummern der zu mountenden Bins (erster = upperdir/rw, Rest = lowerdirs/ro)
+  info "Mounting union (overlayfs)"
   debug "Requested to mount bins: $*"
 
-  # Mount first as rw, shift, and mount the rest ro
-  local branches="br=${BINS_DIR}/$1=rw:"; shift
-  if [[ -n $1 ]]; then
-    for bin in $*; do
-      branches="$branches$BINS_DIR/$bin=ro:"
-    done
+  local upperdir workdir lowerdirs
+
+  if [[ -z "$1" ]]; then
+    # Kein Bin angegeben -> nur Seed sichtbar machen (rw-Schicht temporär & leer)
+    upperdir="$TMP_UPPER"
+    workdir="$TMP_WORKDIR"
+    mkdir -p "$upperdir" "$workdir"
+    lowerdirs="$SQUASH_MOUNT"
+  else
+    local upper_bin="$1"; shift
+    upperdir="$BINS_DIR/$upper_bin"
+    workdir="$WORK_DIR/$upper_bin.work"
+    mkdir -p "$upperdir" "$workdir"
+
+    # Reihenfolge in overlayfs: links = „näher oben“ (neuer), rechts = „tiefer“ (älter)
+    # Wir wollen: ältere Bins unterhalb, ganz unten der Seed
+    lowerdirs=""
+    if [[ $# -gt 0 ]]; then
+      for bin in "$@"; do
+        lowerdirs+="$BINS_DIR/$bin:"
+      done
+    fi
+    lowerdirs+="$SQUASH_MOUNT"
   fi
-  branches="${branches}${SQUASH_MOUNT}=ro"
 
-  mount -t aufs none "$UNION_MOUNT" -o udba=reval,$branches
+  # Overlay mounten
+  # Hinweis: upperdir & workdir müssen auf gleichem FS liegen; workdir muss leer sein.
+  mount -t overlay overlay \
+    -o "lowerdir=$lowerdirs,upperdir=$upperdir,workdir=$workdir" \
+    "$UNION_MOUNT"
 
   return $?
 }
 
 # Unmounting functions
 unmount_union () {
-# Args: none
-# Returns: return code from umount
   info "Unmounting union"
   umount "$UNION_MOUNT" 2>/dev/null
   local ret=$?
   sleep .5
+
+  # temporäre Upper/Work-Dirs (nur wenn leer) aufräumen
+  rmdir "$TMP_WORKDIR" "$TMP_UPPER" 2>/dev/null || true
   return $ret
 }