base-files: improve lib/upgrade/common.sh

Recently, upgrade device autodetection has been added to the mvebu target.
This exposes some shortcomings of the generic export_bootdevice function,
e.g. on the Turris Omnia: export_bootdevice silently reports the root
partition to be the boot device. This makes the sysupgrade process fail at
several places.

Fix this by clearly distinguishing between /proc/cmdline arguments which
specify the boot disk, and those which specify the root partition. Only in
the latter case, strip off the partition, and do it consistently.
root=PARTUUID=<pseudo PARTUUID for MBR> (any partition) and root=/dev/*
(any partition) are accepted.

The root of the problem is that the *existing* export_bootdevice in
/lib/upgrade/common.sh behaves differently, if the kernel is booted with
root=/dev/..., or if it is booted with root=PARTUUID=...

In the former case, it reports back major/minor of the root partition,
in the latter case it reports back major/minor of the complete boot disk.

Targets, which boot with root=/dev/... *and* use export_bootdevice /
export_partdevice, have added workarounds to this behaviour, by specifying
*negative* increments to the export_partdevice function.

Consequently, those targets have to be adapted to use positive increments,
otherwise they are broken by the change to export_bootdevice.

Fixes: 4e8345ff68 ("mvebu: base-files: autodetect upgrade device")
Signed-off-by: Klaus Kudielka <klaus.kudielka@gmail.com>
Tested-by: Tomasz Maciej Nowak <tomek_n@o2.pl>

1 files changed, 19 insertions, 13 deletions

diff --git a/package/base-files/files/lib/upgrade/common.sh b/package/base-files/files/lib/upgrade/common.sh
index b3a29fb32e..bbedeefd26 100644
--- a/package/base-files/files/lib/upgrade/common.sh
+++ b/package/base-files/files/lib/upgrade/common.sh
@@ -101,35 +101,41 @@ get_magic_long() {
 }
 
 export_bootdevice() {
-	local cmdline uuid disk uevent line
+	local cmdline bootdisk rootpart uuid blockdev uevent line
 	local MAJOR MINOR DEVNAME DEVTYPE
 
 	if read cmdline < /proc/cmdline; then
 		case "$cmdline" in
 			*block2mtd=*)
-				disk="${cmdline##*block2mtd=}"
-				disk="${disk%%,*}"
+				bootdisk="${cmdline##*block2mtd=}"
+				bootdisk="${bootdisk%%,*}"
 			;;
 			*root=*)
-				disk="${cmdline##*root=}"
-				disk="${disk%% *}"
+				rootpart="${cmdline##*root=}"
+				rootpart="${rootpart%% *}"
 			;;
 		esac
 
-		case "$disk" in
-			PARTUUID=[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]-02)
-				uuid="${disk#PARTUUID=}"
-				uuid="${uuid%-02}"
-				for disk in $(find /dev -type b); do
-					set -- $(dd if=$disk bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
+		case "$bootdisk" in
+			/dev/*)
+				uevent="/sys/class/block/${bootdisk##*/}/uevent"
+			;;
+		esac
+
+		case "$rootpart" in
+			PARTUUID=[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]-[a-f0-9][a-f0-9])
+				uuid="${rootpart#PARTUUID=}"
+				uuid="${uuid%-[a-f0-9][a-f0-9]}"
+				for blockdev in $(find /dev -type b); do
+					set -- $(dd if=$blockdev bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
 					if [ "$4$3$2$1" = "$uuid" ]; then
-						uevent="/sys/class/block/${disk##*/}/uevent"
+						uevent="/sys/class/block/${blockdev##*/}/uevent"
 						break
 					fi
 				done
 			;;
 			/dev/*)
-				uevent="/sys/class/block/${disk##*/}/uevent"
+				uevent="/sys/class/block/${rootpart##*/}/../uevent"
 			;;
 		esac