Configure dmsetup to fallback to managing device nodes without udevd

pkg/dmlegacy/cleanup/deactivate.go

@@ -9,7 +9,8 @@ import (
 func DeactivateSnapshot(vm *api.VM) error {
 	dmArgs := []string{
 		"remove",
-		vm.SnapshotDev(),
+		"--verifyudev", // if udevd is not running, dmsetup will manage the device node in /dev/mapper
+		util.NewPrefixer().Prefix(vm.GetUID()),
 	}
 
 	// If the base device is visible in "dmsetup", we should remove it

pkg/dmlegacy/loopdev.go

@@ -36,7 +36,11 @@ func (ld *loopDevice) Size512K() (uint64, error) {
 
 // dmsetup uses stdin to read multiline tables, this is a helper function for that
 func runDMSetup(name string, table []byte) error {
-	cmd := exec.Command("dmsetup", "create", name)
+	cmd := exec.Command(
+		"dmsetup", "create",
+		"--verifyudev", // if udevd is not running, dmsetup will manage the device node in /dev/mapper
+		name,
+	)
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
 		return err
@@ -52,7 +56,7 @@ func runDMSetup(name string, table []byte) error {
 
 	out, err := cmd.CombinedOutput()
 	if err != nil {
-		return fmt.Errorf("command %q exited with %q: %v", cmd.Args, out, err)
+		return fmt.Errorf("command %q exited with %q: %w", cmd.Args, out, err)
 	}
 
 	return nil

pkg/dmlegacy/snapshot.go

@@ -17,10 +17,11 @@ import (
 
 const snapshotLockFileName = "ignite-snapshot.lock"
 
-// ActivateSnapshot sets up the snapshot with devicemapper so that it is active and can be used
-func ActivateSnapshot(vm *api.VM) (err error) {
+// ActivateSnapshot sets up the snapshot with devicemapper so that it is active and can be used.
+// It returns the path of the bootable snapshot device.
+func ActivateSnapshot(vm *api.VM) (devicePath string, err error) {
 	device := util.NewPrefixer().Prefix(vm.GetUID())
-	devicePath := vm.SnapshotDev()
+	devicePath = vm.SnapshotDev()
 
 	// Return if the snapshot is already setup
 	if util.FileExists(devicePath) {
@@ -47,7 +48,8 @@ func ActivateSnapshot(vm *api.VM) (err error) {
 	// Create a lockfile and obtain a lock.
 	lock, err := lockfile.New(glpath)
 	if err != nil {
-		return fmt.Errorf("failed to create lock: %v", err)
+		err = fmt.Errorf("failed to create lockfile: %w", err)
+		return
 	}
 	if err = obtainLock(lock); err != nil {
 		return
@@ -105,6 +107,7 @@ func ActivateSnapshot(vm *api.VM) (err error) {
 	// "0 8388608 snapshot /dev/{loop0,mapper/ignite-<uid>-base} /dev/loop1 P 8"
 	dmTable := []byte(fmt.Sprintf("0 %d snapshot %s %s P 8", overlayLoopSize, basePath, overlayLoop.Path()))
 
+	// setup the main boot device
 	if err = runDMSetup(device, dmTable); err != nil {
 		return
 	}

pkg/dmlegacy/vm.go

@@ -83,7 +83,7 @@ func AllocateAndPopulateOverlay(vm *api.VM) error {
 }
 
 func copyToOverlay(vm *api.VM) (err error) {
-	err = ActivateSnapshot(vm)
+	_, err = ActivateSnapshot(vm)
 	if err != nil {
 		return
 	}

pkg/operations/remove.go

@@ -48,7 +48,7 @@ func CleanupVM(vm *api.VM) error {
 	// TODO should this function return a proper error?
 	RemoveVMContainer(inspectResult)
 
-	// After remove the VM container, and the SnapshotDev still there
+	// After removing the VM container, if the Snapshot Device is still there, clean up
 	if _, err := os.Stat(vm.SnapshotDev()); err == nil {
 		// try remove it again with DeactivateSnapshot
 		if err := cleanup.DeactivateSnapshot(vm); err != nil {

pkg/operations/start.go

@@ -25,7 +25,8 @@ func StartVM(vm *api.VM, debug bool) error {
 	RemoveVMContainer(inspectResult)
 
 	// Setup the snapshot overlay filesystem
-	if err := dmlegacy.ActivateSnapshot(vm); err != nil {
+	snapshotDevPath, err := dmlegacy.ActivateSnapshot(vm)
+	if err != nil {
 		return err
 	}
 
@@ -70,7 +71,7 @@ func StartVM(vm *api.VM, debug bool) error {
 			runtime.BindBoth("/dev/mapper/control"), // This enables containerized Ignite to remove its own dm snapshot
 			runtime.BindBoth("/dev/net/tun"),        // Needed for creating TAP adapters
 			runtime.BindBoth("/dev/kvm"),            // Pass through virtualization support
-			runtime.BindBoth(vm.SnapshotDev()),      // The block device to boot from
+			runtime.BindBoth(snapshotDevPath),       // The block device to boot from
 		},
 		StopTimeout:  constants.STOP_TIMEOUT + constants.IGNITE_TIMEOUT,
 		PortBindings: vm.Spec.Network.Ports, // Add the port mappings to Docker