add LVM support for root partition

README.md

@@ -49,6 +49,7 @@ IMDS data.
 As Tiny Cloud is meant to be tiny, it has few dependencies:
 * Busybox (`ash`, `wget`, etc.)
 * `e2fsprogs-extra` (for `resize2fs`)
+* `lvm2` (for resizing LVM volumes)
 * `openssh-server`
 * `partx`
 * `sfdisk`

TODO.md

@@ -20,7 +20,7 @@
 
 * Support for `#network-config`?
 
-* Support LVM partitioning and non-`ext[234]` filesystems?
+* Support non-`ext[234]` filesystems?
 
 * Support other cloud providers...
   * IBM

docs/tiny-cloud.conf.5.scd

@@ -51,6 +51,10 @@ Blank lines and shell comments are ignored.
 *TINY_CLOUD_LOGS*=<path>
 	Log directory used by tiny-cloud. The default is _/var/log_.
 
+*TINY_CLOUD_LV_ALLOCATE*=<percentage>
+	How much space to allocate when expanding the "/" LVM logical volume in
+	percentage. The default is 85 percent of the volume group's space.
+
 *SKIP_INIT_ACTIONS*=<action> ...
 	Whitespace-separated list of init actions to skip during phase execution.
 

lib/tiny-cloud/init

@@ -45,6 +45,33 @@ init__expand_root() {
 		*) return;;
 	esac
 
+	# check if this is an LVM logical volume
+	if lvs --noheadings -o lv_name "$dev" >/dev/null 2>&1; then
+		# LVM volume detected
+		# find the physical volume backing this LV
+		local vg_name=$(lvs --noheadings -o vg_name "$dev" 2>/dev/null | tr -d ' ')
+		local pv_dev=$(pvs --noheadings -o pv_name -S "vg_name=$vg_name" 2>/dev/null | tr -d ' ' | head -n1)
+
+		# get the partition number if PV is on a partition
+		local pv_partition=$(cat "$SYS/class/block/${pv_dev#/dev/}/partition" 2>/dev/null)
+
+		# only resize partition if PV is on a partition (not whole disk)
+		if [ -n "$pv_partition" ]; then
+			# resize the partition containing the PV
+			local pv_volume=$(readlink -f "$SYS/class/block/${pv_dev#/dev/}/..")
+			pv_volume="/dev/${pv_volume##*/}"
+			echo ", +" | $MOCK sfdisk -q --no-reread -N "$pv_partition" "$pv_volume"
+			$MOCK partx -u "$pv_volume"
+		fi
+
+		# resize the physical volume (works for both partition and whole disk)
+		$MOCK pvresize "$pv_dev"
+
+		# extend the logical volume
+		# default leave 15% for snapshots
+		$MOCK lvextend -l +${TINY_CLOUD_LV_ALLOCATE:-85}%VG "$dev"
+	else
+		# standard partition handling (non-LVM)
 		if [ -n "$partition" ]; then
 			# it's a partition, resize it
 			local volume=$(readlink -f "$SYS/class/block/${dev#/dev/}/..")
@@ -52,7 +79,9 @@ init__expand_root() {
 			echo ", +" | $MOCK sfdisk -q --no-reread -N "$partition" "$volume"
 			$MOCK partx -u "$volume"
 		fi
-	# resize filesystem
+	fi
+
+	# resize filesystem (common for both LVM and non-LVM)
 	if [ -e "$dev" ] || [ -n "$MOCK" ]; then
 		$MOCK resize2fs "$dev"
 	fi

lib/tiny-cloud/tiny-cloud.conf

@@ -26,6 +26,10 @@
 # Location of log directory
 #TINY_CLOUD_LOGS=/var/log
 
+# How much space to allocate when expanding the "/" LVM logical volume in percentage
+# Default: leave 15% unallocated for snapshots
+#TINY_CLOUD_LV_ALLOCATE=85
+
 # Explicitly skip these (whitespace delimited) things during init
 # examples: expand_root set_hostname set_ssh_keys save_userdata
 #   decompress_userdata run_userdata

tests/init.test

@@ -11,6 +11,8 @@ lib="$srcdir"/lib/tiny-cloud/init
 init_tests \
 	expand_root \
 	expand_root_partition \
+	expand_root_lvm_partition \
+	expand_root_lvm_whole_disk \
 	ethernets \
 	find_first_interface_up \
 	auto_detect_ethernet_interface \
@@ -69,6 +71,75 @@ expand_root_partition_body() {
 	done
 }
 
+expand_root_lvm_partition_body() {
+	# Test LVM on a partition (e.g., /dev/sda2 -> PV -> VG -> LV)
+	mkdir -p proc sys/class/block \
+		sys/devices/pci0000:00/0000:00:05.0/virtio2/block/vda/vda2 \
+		sys/devices/pci0000:00/0000:00:05.0/virtio2/block/vda/device \
+		dev/mapper
+	ln -s ../../devices/pci0000:00/0000:00:05.0/virtio2/block/vda sys/class/block/vda
+	ln -s ../../devices/pci0000:00/0000:00:05.0/virtio2/block/vda/vda2 sys/class/block/vda2
+	echo 2 > sys/class/block/vda2/partition
+
+	# Create fake LVM device
+	mkdir -p sys/class/block/dm-0
+	ln -s /dev/mapper/vg0-root dev/mapper/vg0-root
+
+	# Mock LVM commands
+	fake_bin lvs <<-EOF
+		#!/bin/sh
+		echo "  vg0"
+	EOF
+	fake_bin pvs <<-EOF
+		#!/bin/sh
+		echo "  /dev/vda2"
+	EOF
+
+	echo "/dev/mapper/vg0-root / ext4 rw,noatime 0 0" > proc/mounts
+	for provider in $PROVIDERS; do
+		CLOUD="$provider" atf_check \
+			-o match:"sfdisk .*/dev/vda" \
+			-o match:"partx .*/dev/vda" \
+			-o match:"pvresize /dev/vda2" \
+			-o match:"lvextend -l \\+85%VG /dev/mapper/vg0-root" \
+			-o match:"resize2fs /dev/mapper/vg0-root" \
+			sh -c ". $lib; init__expand_root"
+	done
+}
+
+expand_root_lvm_whole_disk_body() {
+	# Test LVM on whole disk (e.g., /dev/sdb -> PV -> VG -> LV, no partition)
+	mkdir -p proc sys/class/block \
+		sys/devices/pci0000:00/0000:00:05.0/virtio3/block/vdb/device \
+		dev/mapper
+	ln -s ../../devices/pci0000:00/0000:00:05.0/virtio3/block/vdb sys/class/block/vdb
+
+	# Create fake LVM device
+	mkdir -p sys/class/block/dm-1
+	ln -s /dev/mapper/vg1-root dev/mapper/vg1-root
+
+	# Mock LVM commands - PV is on whole disk (no partition)
+	fake_bin lvs <<-EOF
+		#!/bin/sh
+		echo "  vg1"
+	EOF
+	fake_bin pvs <<-EOF
+		#!/bin/sh
+		echo "  /dev/vdb"
+	EOF
+
+	echo "/dev/mapper/vg1-root / ext4 rw,noatime 0 0" > proc/mounts
+	for provider in $PROVIDERS; do
+		CLOUD="$provider" atf_check \
+			-o match:"pvresize /dev/vdb" \
+			-o match:"lvextend -l \\+85%VG /dev/mapper/vg1-root" \
+			-o match:"resize2fs /dev/mapper/vg1-root" \
+			-o not-match:"sfdisk" \
+			-o not-match:"partx" \
+			sh -c ". $lib; init__expand_root"
+	done
+}
+
 ethernets_body() {
 	fake_interfaces lo br0 eth0 eth2 eth11