From 033d5f798588cecdbf03e0db4b1358561443e162 Mon Sep 17 00:00:00 2001
From: Stephan Gerhold <stephan.gerhold@linaro.org>
Date: Fri, 22 Nov 2024 17:37:03 +0100
Subject: [PATCH] main/postmarketos-initramfs: mount root partition we unlocked
 (MR 5920)

When using an encrypted installation of postmarketOS, the pmos_root_uuid=
on the cmdline only tells us the UUID of the crypto_LUKS partition. Once
the partition is unlocked, we perform the the old unreliable auto detection
again. This might mount the wrong partition if multiple installations of
pmOS are attached to the system.

After we unlock the root partition, we know exactly where the root
partition is supposed to be (= at /dev/mapper/root). Let's use that
directly instead of going through the whole detection sequence again.
---
 main/postmarketos-initramfs/init_functions.sh | 75 +++++++++----------
 1 file changed, 36 insertions(+), 39 deletions(-)

diff --git a/main/postmarketos-initramfs/init_functions.sh b/main/postmarketos-initramfs/init_functions.sh
index bad4da74d..b7bde92dd 100644
--- a/main/postmarketos-initramfs/init_functions.sh
+++ b/main/postmarketos-initramfs/init_functions.sh
@@ -1,6 +1,5 @@
 #!/bin/sh
 # This file will be in /init_functions.sh inside the initramfs.
-ROOT_PARTITION_UNLOCKED=0
 
 # NOTE!!! The file is sourced again in init_2nd.sh, avoid
 # clobbering variables by not setting them if they have
@@ -216,11 +215,26 @@ find_root_partition() {
 	# Short circuit all autodetection logic if pmos_root= or
 	# pmos_root_uuid= is supplied on the kernel cmdline
 	# shellcheck disable=SC2013
-	if [ "$ROOT_PARTITION_UNLOCKED" = 0 ]; then
+	for x in $(cat /proc/cmdline); do
+		if ! [ "$x" = "${x#pmos_root_uuid=}" ]; then
+			path="$(blkid --uuid "${x#pmos_root_uuid=}")"
+			if [ -n "$path" ]; then
+				PMOS_ROOT="$path"
+				break
+			else
+				# Don't fall back to anything if the given UUID wasn't
+				# found
+				return
+			fi
+		fi
+	done
+
+	if [ -z "$PMOS_ROOT" ]; then
+		# shellcheck disable=SC2013
 		for x in $(cat /proc/cmdline); do
-			if ! [ "$x" = "${x#pmos_root_uuid=}" ]; then
-				path="$(blkid --uuid "${x#pmos_root_uuid=}")"
-				if [ -n "$path" ]; then
+			if ! [ "$x" = "${x#pmos_root=}" ]; then
+				path="${x#pmos_root=}"
+				if [ -e "$path" ]; then
 					PMOS_ROOT="$path"
 					break
 				else
@@ -230,40 +244,24 @@ find_root_partition() {
 				fi
 			fi
 		done
+	fi
 
-		if [ -z "$PMOS_ROOT" ]; then
-			for x in $(cat /proc/cmdline); do
-				if ! [ "$x" = "${x#pmos_root=}" ]; then
-					path="${x#pmos_root=}"
-					if [ -e "$path" ]; then
-						PMOS_ROOT="$path"
-						break
-					else
-						# Don't fall back to anything if the given UUID wasn't
-						# found
-						return
-					fi
-				fi
-			done
-		fi
+	# On-device installer: before postmarketOS is installed,
+	# we want to use the installer partition as root. It is the
+	# partition behind pmos_root. pmos_root will either point to
+	# reserved space, or to an unfinished installation.
+	# p1: boot
+	# p2: (reserved space) <--- pmos_root
+	# p3: pmOS_install
+	# Details: https://postmarketos.org/on-device-installer
+	if [ -n "$PMOS_ROOT" ]; then
+		next="$(echo "$PMOS_ROOT" | sed 's/2$/3/')"
 
-		# On-device installer: before postmarketOS is installed,
-		# we want to use the installer partition as root. It is the
-		# partition behind pmos_root. pmos_root will either point to
-		# reserved space, or to an unfinished installation.
-		# p1: boot
-		# p2: (reserved space) <--- pmos_root
-		# p3: pmOS_install
-		# Details: https://postmarketos.org/on-device-installer
-		if [ -n "$PMOS_ROOT" ]; then
-			next="$(echo "$PMOS_ROOT" | sed 's/2$/3/')"
-
-			# If the next partition is labeled pmOS_install (and
-			# not pmOS_deleteme), then postmarketOS is not
-			# installed yet.
-			if blkid | grep "$next" | grep -q pmOS_install; then
-				PMOS_ROOT="$next"
-			fi
+		# If the next partition is labeled pmOS_install (and
+		# not pmOS_deleteme), then postmarketOS is not
+		# installed yet.
+		if blkid | grep "$next" | grep -q pmOS_install; then
+			PMOS_ROOT="$next"
 		fi
 	fi
 
@@ -534,8 +532,7 @@ unlock_root_partition() {
 			fde-unlock "$partition" "$tried"
 			tried=$((tried + 1))
 		done
-		ROOT_PARTITION_UNLOCKED=1
-		PMOS_ROOT=
+		PMOS_ROOT=/dev/mapper/root
 		# Show again the loading splashscreen
 		show_splash "Loading..."
 	fi