device_util_linux.go

// +build linux

/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package util

import (
	"errors"
	"path"
	"strings"
)

// FindMultipathDeviceForDevice given a device name like /dev/sdx, find the devicemapper parent
func (handler *deviceHandler) FindMultipathDeviceForDevice(device string) string {
	io := handler.get_io
	disk, err := findDeviceForPath(device, io)
	if err != nil {
		return ""
	}
	sysPath := "/sys/block/"
	if dirs, err := io.ReadDir(sysPath); err == nil {
		for _, f := range dirs {
			name := f.Name()
			if strings.HasPrefix(name, "dm-") {
				if _, err1 := io.Lstat(sysPath + name + "/slaves/" + disk); err1 == nil {
					return "/dev/" + name
				}
			}
		}
	}
	return ""
}

// findDeviceForPath Find the underlaying disk for a linked path such as /dev/disk/by-path/XXXX or /dev/mapper/XXXX
// will return sdX or hdX etc, if /dev/sdX is passed in then sdX will be returned
func findDeviceForPath(path string, io IoUtil) (string, error) {
	devicePath, err := io.EvalSymlinks(path)
	if err != nil {
		return "", err
	}
	// if path /dev/hdX split into "", "dev", "hdX" then we will
	// return just the last part
	parts := strings.Split(devicePath, "/")
	if len(parts) == 3 && strings.HasPrefix(parts[1], "dev") {
		return parts[2], nil
	}
	return "", errors.New("Illegal path for device " + devicePath)
}

// FindSlaveDevicesOnMultipath given a dm name like /dev/dm-1, find all devices
// which are managed by the devicemapper dm-1.
func (handler *deviceHandler) FindSlaveDevicesOnMultipath(dm string) []string {
	var devices []string
	io := handler.get_io
	// Split path /dev/dm-1 into "", "dev", "dm-1"
	parts := strings.Split(dm, "/")
	if len(parts) != 3 || !strings.HasPrefix(parts[1], "dev") {
		return devices
	}
	disk := parts[2]
	slavesPath := path.Join("/sys/block/", disk, "/slaves/")
	if files, err := io.ReadDir(slavesPath); err == nil {
		for _, f := range files {
			devices = append(devices, path.Join("/dev/", f.Name()))
		}
	}
	return devices
}