deal with jffs2 transition

git-svn-id: svn://svn.openwrt.org/openwrt/trunk/openwrt@278 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/default/target_skeleton/etc/preinit

@@ -1,6 +1,4 @@
 #!/bin/sh
-# executed from squashfs before init to 
-# transfer root to the jffs2 partition
 mount none /proc -t proc
 insmod diag
 echo 0x01 > /proc/sys/diag
@@ -9,12 +7,14 @@ if [ $(cat /proc/sys/reset) = 1 ] ; then
   export FAILSAFE=true
   while :; do { echo $(((X=(X+1)%8)%2)) > /proc/sys/diag; sleep $((X==0)); } done &
 else
+  mount | grep jffs2 1>&- || {
     mtd unlock mtd4
     mount -t jffs2 /dev/mtdblock/4 /jffs
     pivot_root /jffs /jffs/rom
     mount none /dev -t devfs
     mount none /proc -t proc
     umount rom/proc
+  }
 fi
 mount none /tmp -t ramfs
 exec /sbin/init