func NewDeviceSet()

in daemon/graphdriver/devmapper/deviceset.go [2492:2615]
111 lines of code
35 McCabe index (conditional complexity)

func NewDeviceSet(root string, doInit bool, options []string, uidMaps, gidMaps []idtools.IDMap) (*DeviceSet, error) {
	devicemapper.SetDevDir("/dev")

	devices := &DeviceSet{
		root:                  root,
		metaData:              metaData{Devices: make(map[string]*devInfo)},
		dataLoopbackSize:      defaultDataLoopbackSize,
		metaDataLoopbackSize:  defaultMetaDataLoopbackSize,
		baseFsSize:            defaultBaseFsSize,
		overrideUdevSyncCheck: defaultUdevSyncOverride,
		doBlkDiscard:          true,
		thinpBlockSize:        defaultThinpBlockSize,
		deviceIDMap:           make([]byte, deviceIDMapSz),
		deletionWorkerTicker:  time.NewTicker(time.Second * 30),
		uidMaps:               uidMaps,
		gidMaps:               gidMaps,
		minFreeSpacePercent:   defaultMinFreeSpacePercent,
	}

	foundBlkDiscard := false
	for _, option := range options {
		key, val, err := parsers.ParseKeyValueOpt(option)
		if err != nil {
			return nil, err
		}
		key = strings.ToLower(key)
		switch key {
		case "dm.basesize":
			size, err := units.RAMInBytes(val)
			if err != nil {
				return nil, err
			}
			userBaseSize = true
			devices.baseFsSize = uint64(size)
		case "dm.loopdatasize":
			size, err := units.RAMInBytes(val)
			if err != nil {
				return nil, err
			}
			devices.dataLoopbackSize = size
		case "dm.loopmetadatasize":
			size, err := units.RAMInBytes(val)
			if err != nil {
				return nil, err
			}
			devices.metaDataLoopbackSize = size
		case "dm.fs":
			if val != "ext4" && val != "xfs" {
				return nil, fmt.Errorf("devmapper: Unsupported filesystem %s\n", val)
			}
			devices.filesystem = val
		case "dm.mkfsarg":
			devices.mkfsArgs = append(devices.mkfsArgs, val)
		case "dm.mountopt":
			devices.mountOptions = joinMountOptions(devices.mountOptions, val)
		case "dm.metadatadev":
			devices.metadataDevice = val
		case "dm.datadev":
			devices.dataDevice = val
		case "dm.thinpooldev":
			devices.thinPoolDevice = strings.TrimPrefix(val, "/dev/mapper/")
		case "dm.blkdiscard":
			foundBlkDiscard = true
			devices.doBlkDiscard, err = strconv.ParseBool(val)
			if err != nil {
				return nil, err
			}
		case "dm.blocksize":
			size, err := units.RAMInBytes(val)
			if err != nil {
				return nil, err
			}
			// convert to 512b sectors
			devices.thinpBlockSize = uint32(size) >> 9
		case "dm.override_udev_sync_check":
			devices.overrideUdevSyncCheck, err = strconv.ParseBool(val)
			if err != nil {
				return nil, err
			}

		case "dm.use_deferred_removal":
			enableDeferredRemoval, err = strconv.ParseBool(val)
			if err != nil {
				return nil, err
			}

		case "dm.use_deferred_deletion":
			enableDeferredDeletion, err = strconv.ParseBool(val)
			if err != nil {
				return nil, err
			}

		case "dm.min_free_space":
			if !strings.HasSuffix(val, "%") {
				return nil, fmt.Errorf("devmapper: Option dm.min_free_space requires %% suffix")
			}

			valstring := strings.TrimSuffix(val, "%")
			minFreeSpacePercent, err := strconv.ParseUint(valstring, 10, 32)
			if err != nil {
				return nil, err
			}

			if minFreeSpacePercent >= 100 {
				return nil, fmt.Errorf("devmapper: Invalid value %v for option dm.min_free_space", val)
			}

			devices.minFreeSpacePercent = uint32(minFreeSpacePercent)
		default:
			return nil, fmt.Errorf("devmapper: Unknown option %s\n", key)
		}
	}

	// By default, don't do blk discard hack on raw devices, its rarely useful and is expensive
	if !foundBlkDiscard && (devices.dataDevice != "" || devices.thinPoolDevice != "") {
		devices.doBlkDiscard = false
	}

	if err := devices.initDevmapper(doInit); err != nil {
		return nil, err
	}

	return devices, nil
}