Split live rootfs into smaller squashfs layers

iso/overlay/usr/local/bin/bee-remount-medium

@@ -2,7 +2,7 @@
 # bee-remount-medium — find and remount the live ISO medium to /run/live/medium
 #
 # Run this after reconnecting the ISO source disc (USB/CD) if the live medium
-# was lost and /run/live/medium/live/filesystem.squashfs is missing.
+# was lost and /run/live/medium/live/*.squashfs are missing.
 #
 # Usage: bee-remount-medium [--wait]
 #   --wait  keep retrying every 5 seconds until the medium is found (useful
@@ -11,7 +11,7 @@
 set -euo pipefail
 
 MEDIUM_DIR="/run/live/medium"
-SQUASHFS_REL="live/filesystem.squashfs"
+SQUASHFS_GLOB="live/*.squashfs"
 WAIT_MODE=0
 
 for arg in "$@"; do
@@ -56,7 +56,7 @@ try_mount() {
     local tmpdir
     tmpdir=$(mktemp -d /tmp/bee-probe-XXXXXX)
     if mount -o ro "$dev" "$tmpdir" 2>/dev/null; then
-        if [ -f "${tmpdir}/${SQUASHFS_REL}" ]; then
+        if find "${tmpdir}/live" -maxdepth 1 -type f -name '*.squashfs' 2>/dev/null | grep -q .; then
             # Unmount probe mount and mount properly onto live path
             umount "$tmpdir" 2>/dev/null || true
             rmdir "$tmpdir"  2>/dev/null || true
@@ -82,8 +82,9 @@ attempt() {
     for dev in $(find_candidates); do
         log "  Trying $dev ..."
         if try_mount "$dev"; then
-            local sq="${MEDIUM_DIR}/${SQUASHFS_REL}"
-            log "SUCCESS: squashfs available at $sq ($(du -sh "$sq" | cut -f1))"
+            local count
+            count=$(find "${MEDIUM_DIR}/live" -maxdepth 1 -type f -name '*.squashfs' 2>/dev/null | wc -l | tr -d ' ')
+            log "SUCCESS: ${count} squashfs layer(s) available under ${MEDIUM_DIR}/live"
             return 0
         fi
     done
@@ -100,5 +101,5 @@ if [ "$WAIT_MODE" = "1" ]; then
         sleep 5
     done
 else
-    attempt || die "No ISO medium with ${SQUASHFS_REL} found. Reconnect the disc and re-run, or use --wait."
+    attempt || die "No ISO medium with ${SQUASHFS_GLOB} found. Reconnect the disc and re-run, or use --wait."
 fi