add block-extroot, a package for using an external filesystem as rootfs (patch by cshore)

SVN-Revision: 19880

package/block-extroot/files/50_determine_usb_root

@@ -0,0 +1,50 @@
+#!/bin/sh
+# Copyright (C) 2010 Vertical Communications
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+
+
+. /etc/functions.sh
+. /lib/functions/extmount.sh
+. /lib/functions/mount.sh
+
+determine_external_root() {
+	local OLD_UCI_CONFIG_DIR="$UCI_CONFIG_DIR"
+	set_jffs_mp
+	determine_root_device
+
+	# extroot requires extroot and fstab config files, therefore 
+	# we assume configuration is incomplete and not to be used if either of them
+	# is missing (for jffs versions of these files on squashfs image)
+	if [ "$jffs" = "/jffs" ] && [ -r "/jffs/etc/config/fstab" ]; then
+		UCI_CONFIG_DIR="/jffs/etc/config"
+		ER_IS_SQUASHFS=true
+	fi
+
+	# For squashfs on firstboot root_device will be tmpfs for the ramoverlay,
+	# unless there is a saved config, in which case it will be /dev/root,
+	# however in the case of a saved config, it won't be restored until after
+	# this script, so there won't be a config on the first boot after
+	# flashing a squashfs-based filesystem
+	# For ext2, ramdisk, or jffs2 root filesystems root_device is /dev/root
+	# For squashfs after firstboot, root filesystem is /dev/root	
+	# We only use the config from the root or jffs if the root_device is 
+	# /dev/root
+	[ "$root_device" = "/dev/root" ] && {
+		er_load_modules
+		[ -n "$extroot_settle_time" ] && [ "$extroot_settle_time" -gt 0 ] && {
+			sleep $extroot_settle_time
+		} 
+		config_load fstab
+		config_foreach config_mount_by_section mount 1
+		
+		[ "$rootfs_found" = "1" ] && grep -q /overlay /proc/mounts && { 
+			pi_extroot_mount_success=true
+			pi_mount_skip_next=false
+		}
+	}
+	UCI_CONFIG_DIR="$OLD_UCI_CONFIG_DIR"
+}
+
+boot_hook_add preinit_mount_root determine_external_root
+

package/block-extroot/files/60_pivot_usb_root

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+#!/bin/sh
+# Copyright (C) 2010 Vertical Communications
+
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+
+# Determine if we are requested to mount external root
+
+external_root_pivot() {
+	check_skip || [ "$pi_extroot_mount_success" != "true" ] || {
+		echo "switching to external rootfs"
+		if [ "$ER_IS_SQUASHFS" = "true" ]; then
+			umount /jffs
+		fi
+		mount -o remount,ro / && fopivot /overlay /rom && pi_mount_skip_next=true
+	}
+}
+
+boot_hook_add preinit_mount_root external_root_pivot
+

package/block-extroot/files/extmount.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+# Copyright 2010 Vertical Communications
+
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+
+determine_root_device() {
+	root_device="$(mount | grep ' / ' | cut -f1 -d\  | grep -v rootfs )"
+}
+
+set_jffs_mp() {
+	jffs="$(awk '/jffs2/ {print $2}' /proc/mounts)"
+}
+
+er_load_modules() {
+	[ -d $ER_ROOT/etc/modules.d ] && {
+	    cd $ER_ROOT/etc/modules.d && {
+	    	local modules="$(grep -l '# May be required for rootfs' *)"
+	    	cat $modules | sed 's/^\([^#]\)/insmod \1/' | sh 2>&- || : 
+	    }
+	}
+}
+
+