1
0
Fork 0
mirror of https://github.com/moby/moby.git synced 2022-11-09 12:21:53 -05:00
moby--moby/pkg/devicemapper/devmapper.go
Vivek Goyal d929589c1f devmapper: Implement deferred deletion functionality
Finally here is the patch to implement deferred deletion functionality.
Deferred deleted devices are marked as "Deleted" in device meta file. 

First we try to delete the device and only if deletion fails and user has
enabled deferred deletion, device is marked for deferred deletion.

When docker starts up again, we go through list of deleted devices and
try to delete these again.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
2015-10-06 17:37:21 -04:00

862 lines
23 KiB
Go

// +build linux
package devicemapper
import (
"errors"
"fmt"
"os"
"runtime"
"syscall"
"unsafe"
"github.com/Sirupsen/logrus"
)
// DevmapperLogger defines methods for logging with devicemapper.
type DevmapperLogger interface {
DMLog(level int, file string, line int, dmError int, message string)
}
const (
deviceCreate TaskType = iota
deviceReload
deviceRemove
deviceRemoveAll
deviceSuspend
deviceResume
deviceInfo
deviceDeps
deviceRename
deviceVersion
deviceStatus
deviceTable
deviceWaitevent
deviceList
deviceClear
deviceMknodes
deviceListVersions
deviceTargetMsg
deviceSetGeometry
)
const (
addNodeOnResume AddNodeType = iota
addNodeOnCreate
)
// List of errors returned when using devicemapper.
var (
ErrTaskRun = errors.New("dm_task_run failed")
ErrTaskSetName = errors.New("dm_task_set_name failed")
ErrTaskSetMessage = errors.New("dm_task_set_message failed")
ErrTaskSetAddNode = errors.New("dm_task_set_add_node failed")
ErrTaskSetRo = errors.New("dm_task_set_ro failed")
ErrTaskAddTarget = errors.New("dm_task_add_target failed")
ErrTaskSetSector = errors.New("dm_task_set_sector failed")
ErrTaskGetDeps = errors.New("dm_task_get_deps failed")
ErrTaskGetInfo = errors.New("dm_task_get_info failed")
ErrTaskGetDriverVersion = errors.New("dm_task_get_driver_version failed")
ErrTaskDeferredRemove = errors.New("dm_task_deferred_remove failed")
ErrTaskSetCookie = errors.New("dm_task_set_cookie failed")
ErrNilCookie = errors.New("cookie ptr can't be nil")
ErrAttachLoopbackDevice = errors.New("loopback mounting failed")
ErrGetBlockSize = errors.New("Can't get block size")
ErrUdevWait = errors.New("wait on udev cookie failed")
ErrSetDevDir = errors.New("dm_set_dev_dir failed")
ErrGetLibraryVersion = errors.New("dm_get_library_version failed")
ErrCreateRemoveTask = errors.New("Can't create task of type deviceRemove")
ErrRunRemoveDevice = errors.New("running RemoveDevice failed")
ErrInvalidAddNode = errors.New("Invalid AddNode type")
ErrGetLoopbackBackingFile = errors.New("Unable to get loopback backing file")
ErrLoopbackSetCapacity = errors.New("Unable set loopback capacity")
ErrBusy = errors.New("Device is Busy")
ErrDeviceIDExists = errors.New("Device Id Exists")
ErrEnxio = errors.New("No such device or address")
)
var (
dmSawBusy bool
dmSawExist bool
dmSawEnxio bool // No Such Device or Address
)
type (
// Task represents a devicemapper task (like lvcreate, etc.) ; a task is needed for each ioctl
// command to execute.
Task struct {
unmanaged *cdmTask
}
// Deps represents dependents (layer) of a device.
Deps struct {
Count uint32
Filler uint32
Device []uint64
}
// Info represents information about a device.
Info struct {
Exists int
Suspended int
LiveTable int
InactiveTable int
OpenCount int32
EventNr uint32
Major uint32
Minor uint32
ReadOnly int
TargetCount int32
DeferredRemove int
}
// TaskType represents a type of task
TaskType int
// AddNodeType represents a type of node to be added
AddNodeType int
)
// DeviceIDExists returns whether error conveys the information about device Id already
// exist or not. This will be true if device creation or snap creation
// operation fails if device or snap device already exists in pool.
// Current implementation is little crude as it scans the error string
// for exact pattern match. Replacing it with more robust implementation
// is desirable.
func DeviceIDExists(err error) bool {
return fmt.Sprint(err) == fmt.Sprint(ErrDeviceIDExists)
}
func (t *Task) destroy() {
if t != nil {
DmTaskDestroy(t.unmanaged)
runtime.SetFinalizer(t, nil)
}
}
// TaskCreateNamed is a convenience function for TaskCreate when a name
// will be set on the task as well
func TaskCreateNamed(t TaskType, name string) (*Task, error) {
task := TaskCreate(t)
if task == nil {
return nil, fmt.Errorf("Can't create task of type %d", int(t))
}
if err := task.setName(name); err != nil {
return nil, fmt.Errorf("Can't set task name %s", name)
}
return task, nil
}
// TaskCreate initializes a devicemapper task of tasktype
func TaskCreate(tasktype TaskType) *Task {
Ctask := DmTaskCreate(int(tasktype))
if Ctask == nil {
return nil
}
task := &Task{unmanaged: Ctask}
runtime.SetFinalizer(task, (*Task).destroy)
return task
}
func (t *Task) run() error {
if res := DmTaskRun(t.unmanaged); res != 1 {
return ErrTaskRun
}
return nil
}
func (t *Task) setName(name string) error {
if res := DmTaskSetName(t.unmanaged, name); res != 1 {
return ErrTaskSetName
}
return nil
}
func (t *Task) setMessage(message string) error {
if res := DmTaskSetMessage(t.unmanaged, message); res != 1 {
return ErrTaskSetMessage
}
return nil
}
func (t *Task) setSector(sector uint64) error {
if res := DmTaskSetSector(t.unmanaged, sector); res != 1 {
return ErrTaskSetSector
}
return nil
}
func (t *Task) setCookie(cookie *uint, flags uint16) error {
if cookie == nil {
return ErrNilCookie
}
if res := DmTaskSetCookie(t.unmanaged, cookie, flags); res != 1 {
return ErrTaskSetCookie
}
return nil
}
func (t *Task) setAddNode(addNode AddNodeType) error {
if addNode != addNodeOnResume && addNode != addNodeOnCreate {
return ErrInvalidAddNode
}
if res := DmTaskSetAddNode(t.unmanaged, addNode); res != 1 {
return ErrTaskSetAddNode
}
return nil
}
func (t *Task) setRo() error {
if res := DmTaskSetRo(t.unmanaged); res != 1 {
return ErrTaskSetRo
}
return nil
}
func (t *Task) addTarget(start, size uint64, ttype, params string) error {
if res := DmTaskAddTarget(t.unmanaged, start, size,
ttype, params); res != 1 {
return ErrTaskAddTarget
}
return nil
}
func (t *Task) getDeps() (*Deps, error) {
var deps *Deps
if deps = DmTaskGetDeps(t.unmanaged); deps == nil {
return nil, ErrTaskGetDeps
}
return deps, nil
}
func (t *Task) getInfo() (*Info, error) {
info := &Info{}
if res := DmTaskGetInfo(t.unmanaged, info); res != 1 {
return nil, ErrTaskGetInfo
}
return info, nil
}
func (t *Task) getInfoWithDeferred() (*Info, error) {
info := &Info{}
if res := DmTaskGetInfoWithDeferred(t.unmanaged, info); res != 1 {
return nil, ErrTaskGetInfo
}
return info, nil
}
func (t *Task) getDriverVersion() (string, error) {
res := DmTaskGetDriverVersion(t.unmanaged)
if res == "" {
return "", ErrTaskGetDriverVersion
}
return res, nil
}
func (t *Task) getNextTarget(next unsafe.Pointer) (nextPtr unsafe.Pointer, start uint64,
length uint64, targetType string, params string) {
return DmGetNextTarget(t.unmanaged, next, &start, &length,
&targetType, &params),
start, length, targetType, params
}
func getLoopbackBackingFile(file *os.File) (uint64, uint64, error) {
loopInfo, err := ioctlLoopGetStatus64(file.Fd())
if err != nil {
logrus.Errorf("Error get loopback backing file: %s", err)
return 0, 0, ErrGetLoopbackBackingFile
}
return loopInfo.loDevice, loopInfo.loInode, nil
}
// LoopbackSetCapacity reloads the size for the loopback device.
func LoopbackSetCapacity(file *os.File) error {
if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
logrus.Errorf("Error loopbackSetCapacity: %s", err)
return ErrLoopbackSetCapacity
}
return nil
}
// FindLoopDeviceFor returns a loopback device file for the specified file which
// is backing file of a loop back device.
func FindLoopDeviceFor(file *os.File) *os.File {
stat, err := file.Stat()
if err != nil {
return nil
}
targetInode := stat.Sys().(*syscall.Stat_t).Ino
targetDevice := stat.Sys().(*syscall.Stat_t).Dev
for i := 0; true; i++ {
path := fmt.Sprintf("/dev/loop%d", i)
file, err := os.OpenFile(path, os.O_RDWR, 0)
if err != nil {
if os.IsNotExist(err) {
return nil
}
// Ignore all errors until the first not-exist
// we want to continue looking for the file
continue
}
dev, inode, err := getLoopbackBackingFile(file)
if err == nil && dev == targetDevice && inode == targetInode {
return file
}
file.Close()
}
return nil
}
// UdevWait waits for any processes that are waiting for udev to complete the specified cookie.
func UdevWait(cookie *uint) error {
if res := DmUdevWait(*cookie); res != 1 {
logrus.Debugf("Failed to wait on udev cookie %d", *cookie)
return ErrUdevWait
}
return nil
}
// LogInitVerbose is an interface to initialize the verbose logger for the device mapper library.
func LogInitVerbose(level int) {
DmLogInitVerbose(level)
}
var dmLogger DevmapperLogger
// LogInit initializes the logger for the device mapper library.
func LogInit(logger DevmapperLogger) {
dmLogger = logger
LogWithErrnoInit()
}
// SetDevDir sets the dev folder for the device mapper library (usually /dev).
func SetDevDir(dir string) error {
if res := DmSetDevDir(dir); res != 1 {
logrus.Debugf("Error dm_set_dev_dir")
return ErrSetDevDir
}
return nil
}
// GetLibraryVersion returns the device mapper library version.
func GetLibraryVersion() (string, error) {
var version string
if res := DmGetLibraryVersion(&version); res != 1 {
return "", ErrGetLibraryVersion
}
return version, nil
}
// UdevSyncSupported returns whether device-mapper is able to sync with udev
//
// This is essential otherwise race conditions can arise where both udev and
// device-mapper attempt to create and destroy devices.
func UdevSyncSupported() bool {
return DmUdevGetSyncSupport() != 0
}
// UdevSetSyncSupport allows setting whether the udev sync should be enabled.
// The return bool indicates the state of whether the sync is enabled.
func UdevSetSyncSupport(enable bool) bool {
if enable {
DmUdevSetSyncSupport(1)
} else {
DmUdevSetSyncSupport(0)
}
return UdevSyncSupported()
}
// CookieSupported returns whether the version of device-mapper supports the
// use of cookie's in the tasks.
// This is largely a lower level call that other functions use.
func CookieSupported() bool {
return DmCookieSupported() != 0
}
// RemoveDevice is a useful helper for cleaning up a device.
func RemoveDevice(name string) error {
task, err := TaskCreateNamed(deviceRemove, name)
if task == nil {
return err
}
var cookie uint
if err := task.setCookie(&cookie, 0); err != nil {
return fmt.Errorf("Can not set cookie: %s", err)
}
defer UdevWait(&cookie)
dmSawBusy = false // reset before the task is run
if err = task.run(); err != nil {
if dmSawBusy {
return ErrBusy
}
return fmt.Errorf("Error running RemoveDevice %s", err)
}
return nil
}
// RemoveDeviceDeferred is a useful helper for cleaning up a device, but deferred.
func RemoveDeviceDeferred(name string) error {
logrus.Debugf("[devmapper] RemoveDeviceDeferred START(%s)", name)
defer logrus.Debugf("[devmapper] RemoveDeviceDeferred END(%s)", name)
task, err := TaskCreateNamed(deviceRemove, name)
if task == nil {
return err
}
if err := DmTaskDeferredRemove(task.unmanaged); err != 1 {
return ErrTaskDeferredRemove
}
if err = task.run(); err != nil {
return fmt.Errorf("Error running RemoveDeviceDeferred %s", err)
}
return nil
}
// CancelDeferredRemove cancels a deferred remove for a device.
func CancelDeferredRemove(deviceName string) error {
task, err := TaskCreateNamed(deviceTargetMsg, deviceName)
if task == nil {
return err
}
if err := task.setSector(0); err != nil {
return fmt.Errorf("Can't set sector %s", err)
}
if err := task.setMessage(fmt.Sprintf("@cancel_deferred_remove")); err != nil {
return fmt.Errorf("Can't set message %s", err)
}
dmSawBusy = false
dmSawEnxio = false
if err := task.run(); err != nil {
// A device might be being deleted already
if dmSawBusy {
return ErrBusy
} else if dmSawEnxio {
return ErrEnxio
}
return fmt.Errorf("Error running CancelDeferredRemove %s", err)
}
return nil
}
// GetBlockDeviceSize returns the size of a block device identified by the specified file.
func GetBlockDeviceSize(file *os.File) (uint64, error) {
size, err := ioctlBlkGetSize64(file.Fd())
if err != nil {
logrus.Errorf("Error getblockdevicesize: %s", err)
return 0, ErrGetBlockSize
}
return uint64(size), nil
}
// BlockDeviceDiscard runs discard for the given path.
// This is used as a workaround for the kernel not discarding block so
// on the thin pool when we remove a thinp device, so we do it
// manually
func BlockDeviceDiscard(path string) error {
file, err := os.OpenFile(path, os.O_RDWR, 0)
if err != nil {
return err
}
defer file.Close()
size, err := GetBlockDeviceSize(file)
if err != nil {
return err
}
if err := ioctlBlkDiscard(file.Fd(), 0, size); err != nil {
return err
}
// Without this sometimes the remove of the device that happens after
// discard fails with EBUSY.
syscall.Sync()
return nil
}
// CreatePool is the programmatic example of "dmsetup create".
// It creates a device with the specified poolName, data and metadata file and block size.
func CreatePool(poolName string, dataFile, metadataFile *os.File, poolBlockSize uint32) error {
task, err := TaskCreateNamed(deviceCreate, poolName)
if task == nil {
return err
}
size, err := GetBlockDeviceSize(dataFile)
if err != nil {
return fmt.Errorf("Can't get data size %s", err)
}
params := fmt.Sprintf("%s %s %d 32768 1 skip_block_zeroing", metadataFile.Name(), dataFile.Name(), poolBlockSize)
if err := task.addTarget(0, size/512, "thin-pool", params); err != nil {
return fmt.Errorf("Can't add target %s", err)
}
var cookie uint
var flags uint16
flags = DmUdevDisableSubsystemRulesFlag | DmUdevDisableDiskRulesFlag | DmUdevDisableOtherRulesFlag
if err := task.setCookie(&cookie, flags); err != nil {
return fmt.Errorf("Can't set cookie %s", err)
}
defer UdevWait(&cookie)
if err := task.run(); err != nil {
return fmt.Errorf("Error running deviceCreate (CreatePool) %s", err)
}
return nil
}
// ReloadPool is the programmatic example of "dmsetup reload".
// It reloads the table with the specified poolName, data and metadata file and block size.
func ReloadPool(poolName string, dataFile, metadataFile *os.File, poolBlockSize uint32) error {
task, err := TaskCreateNamed(deviceReload, poolName)
if task == nil {
return err
}
size, err := GetBlockDeviceSize(dataFile)
if err != nil {
return fmt.Errorf("Can't get data size %s", err)
}
params := fmt.Sprintf("%s %s %d 32768 1 skip_block_zeroing", metadataFile.Name(), dataFile.Name(), poolBlockSize)
if err := task.addTarget(0, size/512, "thin-pool", params); err != nil {
return fmt.Errorf("Can't add target %s", err)
}
if err := task.run(); err != nil {
return fmt.Errorf("Error running deviceCreate %s", err)
}
return nil
}
// GetDeps is the programmatic example of "dmsetup deps".
// It outputs a list of devices referenced by the live table for the specified device.
func GetDeps(name string) (*Deps, error) {
task, err := TaskCreateNamed(deviceDeps, name)
if task == nil {
return nil, err
}
if err := task.run(); err != nil {
return nil, err
}
return task.getDeps()
}
// GetInfo is the programmatic example of "dmsetup info".
// It outputs some brief information about the device.
func GetInfo(name string) (*Info, error) {
task, err := TaskCreateNamed(deviceInfo, name)
if task == nil {
return nil, err
}
if err := task.run(); err != nil {
return nil, err
}
return task.getInfo()
}
// GetInfoWithDeferred is the programmatic example of "dmsetup info", but deferred.
// It outputs some brief information about the device.
func GetInfoWithDeferred(name string) (*Info, error) {
task, err := TaskCreateNamed(deviceInfo, name)
if task == nil {
return nil, err
}
if err := task.run(); err != nil {
return nil, err
}
return task.getInfoWithDeferred()
}
// GetDriverVersion is the programmatic example of "dmsetup version".
// It outputs version information of the driver.
func GetDriverVersion() (string, error) {
task := TaskCreate(deviceVersion)
if task == nil {
return "", fmt.Errorf("Can't create deviceVersion task")
}
if err := task.run(); err != nil {
return "", err
}
return task.getDriverVersion()
}
// GetStatus is the programmatic example of "dmsetup status".
// It outputs status information for the specified device name.
func GetStatus(name string) (uint64, uint64, string, string, error) {
task, err := TaskCreateNamed(deviceStatus, name)
if task == nil {
logrus.Debugf("GetStatus: Error TaskCreateNamed: %s", err)
return 0, 0, "", "", err
}
if err := task.run(); err != nil {
logrus.Debugf("GetStatus: Error Run: %s", err)
return 0, 0, "", "", err
}
devinfo, err := task.getInfo()
if err != nil {
logrus.Debugf("GetStatus: Error GetInfo: %s", err)
return 0, 0, "", "", err
}
if devinfo.Exists == 0 {
logrus.Debugf("GetStatus: Non existing device %s", name)
return 0, 0, "", "", fmt.Errorf("Non existing device %s", name)
}
_, start, length, targetType, params := task.getNextTarget(unsafe.Pointer(nil))
return start, length, targetType, params, nil
}
// GetTable is the programmatic example for "dmsetup table".
// It outputs the current table for the specified device name.
func GetTable(name string) (uint64, uint64, string, string, error) {
task, err := TaskCreateNamed(deviceTable, name)
if task == nil {
logrus.Debugf("GetTable: Error TaskCreateNamed: %s", err)
return 0, 0, "", "", err
}
if err := task.run(); err != nil {
logrus.Debugf("GetTable: Error Run: %s", err)
return 0, 0, "", "", err
}
devinfo, err := task.getInfo()
if err != nil {
logrus.Debugf("GetTable: Error GetInfo: %s", err)
return 0, 0, "", "", err
}
if devinfo.Exists == 0 {
logrus.Debugf("GetTable: Non existing device %s", name)
return 0, 0, "", "", fmt.Errorf("Non existing device %s", name)
}
_, start, length, targetType, params := task.getNextTarget(unsafe.Pointer(nil))
return start, length, targetType, params, nil
}
// SetTransactionID sets a transaction id for the specified device name.
func SetTransactionID(poolName string, oldID uint64, newID uint64) error {
task, err := TaskCreateNamed(deviceTargetMsg, poolName)
if task == nil {
return err
}
if err := task.setSector(0); err != nil {
return fmt.Errorf("Can't set sector %s", err)
}
if err := task.setMessage(fmt.Sprintf("set_transaction_id %d %d", oldID, newID)); err != nil {
return fmt.Errorf("Can't set message %s", err)
}
if err := task.run(); err != nil {
return fmt.Errorf("Error running SetTransactionID %s", err)
}
return nil
}
// SuspendDevice is the programmatic example of "dmsetup suspend".
// It suspends the specified device.
func SuspendDevice(name string) error {
task, err := TaskCreateNamed(deviceSuspend, name)
if task == nil {
return err
}
if err := task.run(); err != nil {
return fmt.Errorf("Error running deviceSuspend %s", err)
}
return nil
}
// ResumeDevice is the programmatic example of "dmsetup resume".
// It un-suspends the specified device.
func ResumeDevice(name string) error {
task, err := TaskCreateNamed(deviceResume, name)
if task == nil {
return err
}
var cookie uint
if err := task.setCookie(&cookie, 0); err != nil {
return fmt.Errorf("Can't set cookie %s", err)
}
defer UdevWait(&cookie)
if err := task.run(); err != nil {
return fmt.Errorf("Error running deviceResume %s", err)
}
return nil
}
// CreateDevice creates a device with the specified poolName with the specified device id.
func CreateDevice(poolName string, deviceID int) error {
logrus.Debugf("[devmapper] CreateDevice(poolName=%v, deviceID=%v)", poolName, deviceID)
task, err := TaskCreateNamed(deviceTargetMsg, poolName)
if task == nil {
return err
}
if err := task.setSector(0); err != nil {
return fmt.Errorf("Can't set sector %s", err)
}
if err := task.setMessage(fmt.Sprintf("create_thin %d", deviceID)); err != nil {
return fmt.Errorf("Can't set message %s", err)
}
dmSawExist = false // reset before the task is run
if err := task.run(); err != nil {
// Caller wants to know about ErrDeviceIDExists so that it can try with a different device id.
if dmSawExist {
return ErrDeviceIDExists
}
return fmt.Errorf("Error running CreateDevice %s", err)
}
return nil
}
// DeleteDevice deletes a device with the specified poolName with the specified device id.
func DeleteDevice(poolName string, deviceID int) error {
task, err := TaskCreateNamed(deviceTargetMsg, poolName)
if task == nil {
return err
}
if err := task.setSector(0); err != nil {
return fmt.Errorf("Can't set sector %s", err)
}
if err := task.setMessage(fmt.Sprintf("delete %d", deviceID)); err != nil {
return fmt.Errorf("Can't set message %s", err)
}
dmSawBusy = false
if err := task.run(); err != nil {
if dmSawBusy {
return ErrBusy
}
return fmt.Errorf("Error running DeleteDevice %s", err)
}
return nil
}
// ActivateDevice activates the device identified by the specified
// poolName, name and deviceID with the specified size.
func ActivateDevice(poolName string, name string, deviceID int, size uint64) error {
return activateDevice(poolName, name, deviceID, size, "")
}
// ActivateDeviceWithExternal activates the device identified by the specified
// poolName, name and deviceID with the specified size.
func ActivateDeviceWithExternal(poolName string, name string, deviceID int, size uint64, external string) error {
return activateDevice(poolName, name, deviceID, size, external)
}
func activateDevice(poolName string, name string, deviceID int, size uint64, external string) error {
task, err := TaskCreateNamed(deviceCreate, name)
if task == nil {
return err
}
var params string
if len(external) > 0 {
params = fmt.Sprintf("%s %d %s", poolName, deviceID, external)
} else {
params = fmt.Sprintf("%s %d", poolName, deviceID)
}
if err := task.addTarget(0, size/512, "thin", params); err != nil {
return fmt.Errorf("Can't add target %s", err)
}
if err := task.setAddNode(addNodeOnCreate); err != nil {
return fmt.Errorf("Can't add node %s", err)
}
var cookie uint
if err := task.setCookie(&cookie, 0); err != nil {
return fmt.Errorf("Can't set cookie %s", err)
}
defer UdevWait(&cookie)
if err := task.run(); err != nil {
return fmt.Errorf("Error running deviceCreate (ActivateDevice) %s", err)
}
return nil
}
// CreateSnapDevice creates a snapshot based on the device identified by the baseName and baseDeviceId,
func CreateSnapDevice(poolName string, deviceID int, baseName string, baseDeviceID int) error {
devinfo, _ := GetInfo(baseName)
doSuspend := devinfo != nil && devinfo.Exists != 0
if doSuspend {
if err := SuspendDevice(baseName); err != nil {
return err
}
}
task, err := TaskCreateNamed(deviceTargetMsg, poolName)
if task == nil {
if doSuspend {
ResumeDevice(baseName)
}
return err
}
if err := task.setSector(0); err != nil {
if doSuspend {
ResumeDevice(baseName)
}
return fmt.Errorf("Can't set sector %s", err)
}
if err := task.setMessage(fmt.Sprintf("create_snap %d %d", deviceID, baseDeviceID)); err != nil {
if doSuspend {
ResumeDevice(baseName)
}
return fmt.Errorf("Can't set message %s", err)
}
dmSawExist = false // reset before the task is run
if err := task.run(); err != nil {
if doSuspend {
ResumeDevice(baseName)
}
// Caller wants to know about ErrDeviceIDExists so that it can try with a different device id.
if dmSawExist {
return ErrDeviceIDExists
}
return fmt.Errorf("Error running deviceCreate (createSnapDevice) %s", err)
}
if doSuspend {
if err := ResumeDevice(baseName); err != nil {
return err
}
}
return nil
}