From db8ea24da217f5adc42d84000b97375ba5f36ee0 Mon Sep 17 00:00:00 2001
From: Dmitry Ermakov <de@dimer.org.ua>
Date: Mon, 13 Mar 2023 00:10:32 +0300
Subject: [PATCH] Do not mount overlay on a certain R/W rootfs

---
 general/overlay/init | 71 ++++++++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 32 deletions(-)

diff --git a/general/overlay/init b/general/overlay/init
index 3eda4970..25a0136e 100755
--- a/general/overlay/init
+++ b/general/overlay/init
@@ -1,7 +1,6 @@
 #!/bin/sh
 
-on_exit()
-{
+on_exit() {
   mountpoint -q /proc && umount /proc
   exec /sbin/init $*
 }
@@ -11,36 +10,44 @@ trap on_exit 0
 mount -t proc proc /proc || exit
 grep -q overlay /proc/filesystems || exit
 
-if grep -q ubifs /proc/cmdline; then
-  mount -t ubifs ubi0:rootfs_data /overlay
-else
-  mtdblkdev=`awk -F ':' '/rootfs_data/ {print $1}' /proc/mtd | sed 's/mtd/mtdblock/'`
-  mtdchrdev=`grep 'rootfs_data' /proc/mtd | cut -d: -f1`
-  mount -t jffs2 /dev/${mtdblkdev} /overlay
-  
-  if [ $? -ne 0 ] || { dmesg | grep "jffs2.*: Magic bitmask.*not found" > /dev/null 2>&1; } then
-	echo "jffs2 health check error, format required!"
-	flash_eraseall -j /dev/${mtdchrdev}
-	echo "Done! Remounting..."
-	mount -t jffs2 /dev/${mtdblkdev} /overlay || mount -t tmpfs tmpfs /overlay || exit
-	if ! cat /proc/mounts | grep ${mtdblkdev}; then
-	  echo "--------------------------------"
-	  echo "Crash - your flash in the trash!"
-	  echo "--------------------------------"
-	fi
+if ! grep -q 'root=.*nfs\|mmcblk\|ram' /proc/cmdline; then
+  if grep -q ubifs /proc/cmdline; then
+    mount -t ubifs ubi0:rootfs_data /overlay
+  else
+    mtdblkdev=$(awk -F ':' '/rootfs_data/ {print $1}' /proc/mtd | sed 's/mtd/mtdblock/')
+    mtdchrdev=$(grep 'rootfs_data' /proc/mtd | cut -d: -f1)
+    mount -t jffs2 /dev/${mtdblkdev} /overlay
+
+    if [ $? -ne 0 ] || { dmesg | grep "jffs2.*: Magic bitmask.*not found" >/dev/null 2>&1; }; then
+      echo "jffs2 health check error, format required!"
+      flash_eraseall -j /dev/${mtdchrdev}
+      echo "Done! Remounting..."
+      mount -t jffs2 /dev/${mtdblkdev} /overlay || mount -t tmpfs tmpfs /overlay || exit
+      if ! cat /proc/mounts | grep ${mtdblkdev}; then
+        echo "--------------------------------"
+        echo "Crash - your flash in the trash!"
+        echo "--------------------------------"
+      fi
+    fi
   fi
-fi
 
-if grep -q overlayfs /proc/filesystems; then
-  mount -t overlayfs overlayfs -o lowerdir=/,upperdir=/overlay,ro /mnt || { umount /overlay; exit; }
-else
-  overlay_rootdir=/overlay/root
-  overlay_workdir=/overlay/work
-  mkdir -p ${overlay_rootdir} ${overlay_workdir}
-  mount -t overlay overlay -o lowerdir=/,upperdir=${overlay_rootdir},workdir=${overlay_workdir} /mnt || { umount /overlay; exit; }
-fi
+  if grep -q overlayfs /proc/filesystems; then
+    mount -t overlayfs overlayfs -o lowerdir=/,upperdir=/overlay,ro /mnt || {
+      umount /overlay
+      exit
+    }
+  else
+    overlay_rootdir=/overlay/root
+    overlay_workdir=/overlay/work
+    mkdir -p ${overlay_rootdir} ${overlay_workdir}
+    mount -t overlay overlay -o lowerdir=/,upperdir=${overlay_rootdir},workdir=${overlay_workdir} /mnt || {
+      umount /overlay
+      exit
+    }
+  fi
 
-pivot_root /mnt /mnt/rom
-mount -o noatime,move /rom/proc /proc
-mount -o noatime,move /rom/dev /dev
-mount -o noatime,move /rom/overlay /overlay
+  pivot_root /mnt /mnt/rom
+  mount -o noatime,move /rom/proc /proc
+  mount -o noatime,move /rom/dev /dev
+  mount -o noatime,move /rom/overlay /overlay
+fi