[openwrt/openwrt] base-files: minimize critical time in sysupgrade

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/9ba28f978c76692876f4f5bc7ad66e8fc73084fb

commit 9ba28f978c76692876f4f5bc7ad66e8fc73084fb
Author: Rodrigo Balerdi <lanchon at gmail.com>
AuthorDate: Fri Apr 15 07:20:28 2022 -0300

    base-files: minimize critical time in sysupgrade
    
    Attempt to minimize the time during which an interrupted nand sysupgrade
    can lead to a non-functional device by flushing caches before starting
    the upgrade procedure.
    
    Signed-off-by: Rodrigo Balerdi <lanchon at gmail.com>
---
 package/base-files/files/lib/upgrade/nand.sh | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/package/base-files/files/lib/upgrade/nand.sh b/package/base-files/files/lib/upgrade/nand.sh
index 371bdf7d77..5ecdb0ff23 100644
--- a/package/base-files/files/lib/upgrade/nand.sh
+++ b/package/base-files/files/lib/upgrade/nand.sh
@@ -335,15 +335,16 @@ nand_upgrade_tar() {
 
 # Recognize type of passed file and start the upgrade process
 nand_do_upgrade() {
-	local file_type=$(identify $1)
+	local file_type=$(identify "$1")
 
 	[ ! "$(find_mtd_index "$CI_UBIPART")" ] && CI_UBIPART=rootfs
 
+	sync
 	case "$file_type" in
-		"fit")		nand_upgrade_fit $1;;
-		"ubi")		nand_upgrade_ubinized $1;;
-		"ubifs")	nand_upgrade_ubifs $1;;
-		*)		nand_upgrade_tar $1;;
+		"fit")		nand_upgrade_fit "$1";;
+		"ubi")		nand_upgrade_ubinized "$1";;
+		"ubifs")	nand_upgrade_ubifs "$1";;
+		*)		nand_upgrade_tar "$1";;
 	esac
 }