base-files: MAJOR/MINOR not sequential, use DISKSEQ instead

Export the unique, monotonic DISKSEQ sequence drive number instead of its
major/minor numbers to identify the boot disk and directly match the partition
in export_partdevice with PARTN.

The MINOR blockdevice numbers are not guaranteed sequential across disks, it
can happen that disks enumerate before their partitions are probed, resulting
in interleaved MINOR numbers breaking the partition offset calculation:

major minor  #blocks  name
 259        0  250059096 nvme0n1
 259        2       8192 nvme0n1p1
 259        3     491520 nvme0n1p2
 259        4        239 nvme0n1p128
 259        1  250059096 nvme1n1
 259        5  250057728 nvme1n1p1

Signed-off-by: Clemens Hopfer <openwrt@wireloss.net>
Link: openwrt/openwrt#18962
Signed-off-by: Robert Marko <robimarko@gmail.com>

Author: oe1rfc

package/base-files/files/lib/upgrade/common.sh

@@ -167,7 +167,7 @@ part_magic_fat() {
 
 export_bootdevice() {
 	local cmdline uuid blockdev uevent line class
-	local MAJOR MINOR DEVNAME DEVTYPE
+	local MAJOR MINOR DEVNAME DEVTYPE DISKSEQ PARTN
 	local rootpart="$(cmdline_get_var root)"
 
 	case "$rootpart" in
@@ -216,25 +216,26 @@ export_bootdevice() {
 		while read line; do
 			export -n "$line"
 		done < "$uevent"
-		export BOOTDEV_MAJOR=$MAJOR
-		export BOOTDEV_MINOR=$MINOR
+		export BOOTDEV_DISKSEQ=$DISKSEQ
 		return 0
 	fi
 
 	return 1
 }
 
 export_partdevice() {
-	local var="$1" offset="$2"
-	local uevent line MAJOR MINOR DEVNAME DEVTYPE
+	local var="$1" partn="$2"
+	local uevent line MAJOR MINOR DEVNAME DEVTYPE DISKSEQ PARTN
 
 	for uevent in /sys/class/block/*/uevent; do
 		while read line; do
 			export -n "$line"
 		done < "$uevent"
-		if [ "$BOOTDEV_MAJOR" = "$MAJOR" -a $(($BOOTDEV_MINOR + $offset)) = "$MINOR" -a -b "/dev/$DEVNAME" ]; then
-			export "$var=$DEVNAME"
-			return 0
+		if [ "$BOOTDEV_DISKSEQ" = "$DISKSEQ" -a -b "/dev/$DEVNAME" ]; then
+			if [ "$PARTN" = "$partn" -a "$DEVTYPE" = "partition" ] || [ "$partn" = "0" -a "$DEVTYPE" = "disk" ]; then
+				export "$var=$DEVNAME"
+				return 0
+			fi
 		fi
 	done
 

target/linux/stm32/base-files/lib/upgrade/platform.sh

@@ -31,8 +31,7 @@ export_bootdevice() {
 		while read line; do
 			export -n "$line"
 		done < "$uevent"
-		export BOOTDEV_MAJOR=$MAJOR
-		export BOOTDEV_MINOR=$MINOR
+		export BOOTDEV_DISKSEQ=$DISKSEQ
 		return 0
 	fi