sysupgrade-nand: allow limiting rootfs_data by setting env variable

Check if firmware environment variable 'rootfs_data_max' exists and is
set to a numerical value greater than 0. If so, limit rootfs_data
volume to that size instead of using the maximum available size.

This is useful on devices with lots of flash where users may want to
have eg. a volume for persistent logs and statistics or for external
applications/containers. Persistence on rootfs overlay is limited by
the size of memory available during the sysugprade process as that
data needs to be copied to RAM while the volume is being recreated
during sysupgrade. Hence it is unsuitable for keeping larger amounts
of data accross upgrade which makes additional volume(s) for
application data desirable.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

diff --git a/package/base-files/files/lib/upgrade/nand.sh b/package/base-files/files/lib/upgrade/nand.sh
index 7cf95c013982b3a6d6bb28b63a1471c7c4576daf..2b766480d76ddcfb054d2b9e0c2d88a69cf0f188 100644 (file)
--- a/package/base-files/files/lib/upgrade/nand.sh
+++ b/package/base-files/files/lib/upgrade/nand.sh
@@ -117,6 +117,9 @@ nand_restore_config() {
 nand_upgrade_prepare_ubi() {
        local rootfs_length="$1"
        local rootfs_type="$2"
+       local rootfs_data_max="$(fw_printenv -n rootfs_data_max 2>/dev/null)"
+       [ -n "$rootfs_data_max" ] && rootfs_data_max=$(($rootfs_data_max))
+
        local kernel_length="$3"
        local has_env="${4:-0}"
 
@@ -176,11 +179,11 @@ nand_upgrade_prepare_ubi() {
 
        # update rootfs
        if [ -n "$rootfs_length" ]; then
-               local root_size_param
+               local rootfs_size_param
                if [ "$rootfs_type" = "ubifs" ]; then
-                       root_size_param="-m"
+                       rootfs_size_param="-m"
                else
-                       root_size_param="-s $rootfs_length"
+                       rootfs_size_param="-s $rootfs_length"
                fi
                if ! ubimkvol /dev/$ubidev -N $CI_ROOTPART $rootfs_size_param; then
                        echo "cannot create rootfs volume"
@@ -190,7 +193,16 @@ nand_upgrade_prepare_ubi() {
 
        # create rootfs_data for non-ubifs rootfs
        if [ "$rootfs_type" != "ubifs" ]; then
-               if ! ubimkvol /dev/$ubidev -N rootfs_data -m; then
+               local availeb=$(cat /sys/devices/virtual/ubi/$ubidev/avail_eraseblocks)
+               local ebsize=$(cat /sys/devices/virtual/ubi/$ubidev/eraseblock_size)
+               local avail_size=$(( $availeb * $ebsize ))
+               local rootfs_data_size_param="-m"
+               if [ -n "$rootfs_data_max" ] &&
+                  [ "$rootfs_data_max" != "0" ] &&
+                  [ "$rootfs_data_max" -le "$avail_size" ]; then
+                       rootfs_data_size_param="-s $rootfs_data_max"
+               fi
+               if ! ubimkvol /dev/$ubidev -N rootfs_data $rootfs_data_size_param; then
                        echo "cannot initialize rootfs_data volume"
                        return 1
                fi