Defer resolving block device IDs to local_device_setup

Since we now invoke blkid to resolve block device IDs rather than
relying on symlinks under /dev/disk, resolve_device just doesn't work
until the specified device exists.  So we need to use it in the
multiple existence checks in local_device_setup, and nowhere else.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

init

@@ -79,7 +79,6 @@ for x in $(cat /proc/cmdline); do
 		;;
 	root=*)
 		ROOT=${x#root=}
-		ROOT=$(resolve_device "$ROOT")
 		if [ -z "${BOOT}" ] && [ "$ROOT" = "/dev/nfs" ]; then
 			BOOT=nfs
 		fi

scripts/functions

@@ -300,15 +300,15 @@ resolve_device() {
 	case "$DEV" in
 	LABEL=* | UUID=* | PARTLABEL=* | PARTUUID=*)
 		if command -v blkid >/dev/null 2>&1; then
-			DEV="$(blkid -l -t "$DEV" -o device)"
+			DEV="$(blkid -l -t "$DEV" -o device)" || return 1
 		else
 			log_warning_msg "blkid not present, so cannot resolve $DEV"
+			return 1
 		fi
 		;;
 	esac
-	# Only canonicalise if a valid file, in case $DEV isn't a filename
-	[ -e "$DEV" ] && DEV=$(readlink -f "$DEV")
-	echo "$DEV"
+	[ -e "$DEV" ] || return 1
+	readlink -f "$DEV"
 }
 
 # Check a file system.

scripts/local

@@ -38,12 +38,14 @@ local_bottom()
 	local_top_used=no
 }
 
-# $1=device to mount
+# $1=device ID to mount
 # $2=optionname (for root and etc)
+# Sets $DEV to the resolved device node
 local_device_setup()
 {
-	local dev="$1"
+	local dev_id="$1"
 	local name="$2"
+	local real_dev
 
 	wait_for_udev 10
 
@@ -51,12 +53,15 @@ local_device_setup()
 	# doesn't work with a char device like ubi.
 	if [ -n "$UBIMTD" ]; then
 		modprobe ubi mtd=$UBIMTD
+		DEV="${dev_id}"
 		return
 	fi
 
-	# Don't wait for a root device that doesn't have a corresponding
-	# device in /dev (ie, mtd0)
-	if [ "${dev#/dev}" = "${dev}" ]; then
+	# Don't wait for a device that doesn't have a corresponding
+	# device in /dev and isn't resolvable by blkid (e.g. mtd0)
+	if [ "${dev_id#/dev}" = "${dev_id}" ] &&
+	   [ "${dev_id#*=}" = "${dev_id}" ]; then
+		DEV="${dev_id}"
 		return
 	fi
 
@@ -64,7 +69,8 @@ local_device_setup()
 	# to allow for asynchronous device discovery (e.g. USB).  We
 	# also need to keep invoking the local-block scripts in case
 	# there are devices stacked on top of those.
-	if [ ! -e "${dev}" ] || ! $(get_fstype "${dev}" >/dev/null); then
+	if ! real_dev=$(resolve_device "${dev_id}") ||
+	   ! get_fstype "${real_dev}" >/dev/null; then
 		log_begin_msg "Waiting for ${name} file system"
 
 		# Timeout is max(30, rootdelay) seconds (approximately)
@@ -75,8 +81,9 @@ local_device_setup()
 
 		while true; do
 			sleep 1
-			local_block "${dev}"
-			if [ -e "${dev}" ] && get_fstype "${dev}" >/dev/null; then
+			local_block "${dev_id}"
+			if real_dev=$(resolve_device "${dev_id}") &&
+			   get_fstype "${real_dev}" >/dev/null; then
 				wait_for_udev 10
 				log_end_msg 0
 				break
@@ -90,7 +97,8 @@ local_device_setup()
 	fi
 
 	# We've given up, but we'll let the user fix matters if they can
-	while [ ! -e "${dev}" ]; do
+	while ! real_dev=$(resolve_device "${dev_id}") ||
+	      ! get_fstype "${real_dev}" >/dev/null; do
 		echo "Gave up waiting for ${name} device.  Common problems:"
 		echo " - Boot args (cat /proc/cmdline)"
 		echo "   - Check rootdelay= (did the system wait long enough?)"
@@ -98,14 +106,17 @@ local_device_setup()
 			echo "   - Check root= (did the system wait for the right device?)"
 		fi
 		echo " - Missing modules (cat /proc/modules; ls /dev)"
-		panic "ALERT!  ${dev} does not exist.  Dropping to a shell!"
+		panic "ALERT!  ${dev_id} does not exist.  Dropping to a shell!"
 	done
+
+	DEV="${real_dev}"
 }
 
 local_mount_root()
 {
 	local_top
 	local_device_setup "${ROOT}" root
+	ROOT="${DEV}"
 
 	# Get the root filesystem type if not set
 	if [ -z "${ROOTFSTYPE}" ]; then
@@ -116,8 +127,6 @@ local_mount_root()
 
 	local_premount
 
-	ROOT=$(resolve_device "$ROOT")
-
 	if [ "${readonly}" = "y" ]; then
 		roflag=-r
 	else
@@ -141,14 +150,12 @@ local_mount_root()
 local_mount_fs()
 {
 	read_fstab_entry "$1"
-	MNT_FSNAME=$(resolve_device "$MNT_FSNAME")
 
 	local_device_setup "$MNT_FSNAME" "$1"
+	MNT_FSNAME="${DEV}"
 
 	local_premount
 
-	MNT_FSNAME=$(resolve_device "$MNT_FSNAME")
-
 	if [ "${readonly}" = "y" ]; then
 		roflag=-r
 	else