[openwrt/openwrt] gemini: use tar stream to write firmware

[LEDE Commits]

linusw pushed a commit to openwrt/openwrt.git, branch openwrt-25.12:
https://git.openwrt.org/40b5a83fdb9934e92ee875668c828112cce61881

commit 40b5a83fdb9934e92ee875668c828112cce61881
Author: Linus Walleij <linusw at kernel.org>
AuthorDate: Thu Jan 29 23:40:50 2026 +0100

    gemini: use tar stream to write firmware
    
    The firmware update file can get big, so instead of extracting
    the whole file into the tmp folder potentially running out of space
    and make the upgrade fail, stream from tar xvf -O directly to the
    mtd write command.
    
    Refactor the checking of partitions and the actual upgrade into
    two steps when we are at it.
    
    Link: https://github.com/openwrt/openwrt/pull/21782
    (cherry picked from commit 1977301b5f8f76b4d04b5950b09b2fd7cf607bc4)
    Link: https://github.com/openwrt/openwrt/pull/21973
    Signed-off-by: Linus Walleij <linusw at kernel.org>
---
 .../gemini/base-files/lib/upgrade/platform.sh      | 28 +++++++++++++---------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/target/linux/gemini/base-files/lib/upgrade/platform.sh b/target/linux/gemini/base-files/lib/upgrade/platform.sh
index f7620fd244..0547be8fb0 100644
--- a/target/linux/gemini/base-files/lib/upgrade/platform.sh
+++ b/target/linux/gemini/base-files/lib/upgrade/platform.sh
@@ -1,7 +1,7 @@
 REQUIRE_IMAGE_METADATA=1
 MTDSYSFS=/sys/class/mtd
 
-gemini_do_platform_upgrade() {
+gemini_check_redboot_parts() {
 	MTD1OF=`cat ${MTDSYSFS}/mtd1/offset`
 	MTD2OF=`cat ${MTDSYSFS}/mtd2/offset`
 	MTD3OF=`cat ${MTDSYSFS}/mtd3/offset`
@@ -54,19 +54,23 @@ gemini_do_platform_upgrade() {
 		echo "MTD3 has wrong name, aborting" >&2
 		exit 1
 	fi
+}
+
+gemini_do_platform_upgrade() {
 	echo "Extract the three firmware parts"
-	tar xvfz "$1"; rm "$1"
-	sync
 	echo 3 > /proc/sys/vm/drop_caches
 	echo "COMMENCING UPGRADE. BE PATIENT, THIS IS NOT FAST!"
-	echo "Upgrade Kern partition (kernel part 1, $2 erase blocks)"
-	mtd write zImage Kern
+	KFSZ=$(tar xfz "$1" zImage -O | wc -c)
+	echo "Upgrade Kern partition (kernel part 1, size ${KFSZ})"
+	tar xfz "$1" zImage -O | mtd write - Kern
 	[ $? -ne 0 ] && exit 1
-	echo "Upgrade Ramdisk partition (kernel part 2, $3 erase blocks)"
-	mtd write rd.gz Ramdisk
+	RFSZ=$(tar xfz "$1" rd.gz -O | wc -c)
+	echo "Upgrade Ramdisk partition (kernel part 2, size ${RFSZ})"
+	tar xfz "$1" rd.gz -O | mtd write - Ramdisk
 	[ $? -ne 0 ] && exit 1
-	echo "Upgrade Application partition (rootfs, $4 erase blocks)"
-	mtd write hddapp.tgz Application
+	AFSZ=$(tar xfz "$1" hddapp.tgz -O | wc -c)
+	echo "Upgrade Application partition (rootfs, size ${AFSZ})"
+	tar xfz "$1" hddapp.tgz -O | mtd write - Application
 	[ $? -ne 0 ] && exit 1
 }
 
@@ -98,10 +102,12 @@ platform_do_upgrade() {
 		;;
 	itian,sq201|\
 	storlink,gemini324)
-		gemini_do_platform_upgrade "$1" 16 48 48
+		gemini_check_redboot_parts "$1" 16 48 48
+		gemini_do_platform_upgrade "$1"
 		;;
 	raidsonic,ib-4220-b)
-		gemini_do_platform_upgrade "$1" 24 48 48
+		gemini_check_redboot_parts "$1" 24 48 48
+		gemini_do_platform_upgrade "$1"
 		;;
 	esac
 }