[openwrt/openwrt] sysupgrade-nand: allow limiting rootfs_data by setting env variable

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/5c10f26c28031c0d7e72b672623727adb5df7b2d

commit 5c10f26c28031c0d7e72b672623727adb5df7b2d
Author: Daniel Golle <daniel at makrotopia.org>
AuthorDate: Wed Feb 17 15:17:49 2021 +0000

    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 at makrotopia.org>
---
 package/base-files/files/lib/upgrade/nand.sh | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/package/base-files/files/lib/upgrade/nand.sh b/package/base-files/files/lib/upgrade/nand.sh
index 7cf95c0139..2b766480d7 100644
--- 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