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devmapper: Store metadata in one file per device
This allows multiple instances of the backend in different containers to access devices (although generally only one can modify/create them). Any old metadata is converted on the first run. Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
This commit is contained in:
Alexander Larsson
parent
f26203cf54
commit
6d631968fa
2 changed files with 107 additions and 83 deletions
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@ -106,7 +106,19 @@ func (devices *DeviceSet) loopbackDir() string {
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return path.Join(devices.root, "devicemapper")
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}
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func (devices *DeviceSet) jsonFile() string {
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func (devices *DeviceSet) metadataDir() string {
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return path.Join(devices.root, "metadata")
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}
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func (devices *DeviceSet) metadataFile(info *DevInfo) string {
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file := info.Hash
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if file == "" {
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file = "base"
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}
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return path.Join(devices.metadataDir(), file)
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}
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func (devices *DeviceSet) oldMetadataFile() string {
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return path.Join(devices.loopbackDir(), "json")
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}
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@ -161,14 +173,19 @@ func (devices *DeviceSet) allocateTransactionId() uint64 {
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return devices.NewTransactionId
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}
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func (devices *DeviceSet) saveMetadata() error {
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devices.devicesLock.Lock()
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jsonData, err := json.Marshal(devices.MetaData)
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devices.devicesLock.Unlock()
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func (devices *DeviceSet) removeMetadata(info *DevInfo) error {
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if err := osRemoveAll(devices.metadataFile(info)); err != nil {
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return fmt.Errorf("Error removing metadata file %s: %s", devices.metadataFile(info), err)
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}
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return nil
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}
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func (devices *DeviceSet) saveMetadata(info *DevInfo) error {
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jsonData, err := json.Marshal(info)
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if err != nil {
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return fmt.Errorf("Error encoding metadata to json: %s", err)
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}
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tmpFile, err := ioutil.TempFile(filepath.Dir(devices.jsonFile()), ".json")
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tmpFile, err := ioutil.TempFile(devices.metadataDir(), ".tmp")
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if err != nil {
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return fmt.Errorf("Error creating metadata file: %s", err)
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}
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@ -186,7 +203,7 @@ func (devices *DeviceSet) saveMetadata() error {
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if err := tmpFile.Close(); err != nil {
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return fmt.Errorf("Error closing metadata file %s: %s", tmpFile.Name(), err)
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}
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if err := osRename(tmpFile.Name(), devices.jsonFile()); err != nil {
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if err := osRename(tmpFile.Name(), devices.metadataFile(info)); err != nil {
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return fmt.Errorf("Error committing metadata file %s: %s", tmpFile.Name(), err)
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}
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@ -204,7 +221,12 @@ func (devices *DeviceSet) lookupDevice(hash string) (*DevInfo, error) {
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defer devices.devicesLock.Unlock()
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info := devices.Devices[hash]
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if info == nil {
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return nil, fmt.Errorf("Unknown device %s", hash)
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info = devices.loadMetadata(hash)
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if info == nil {
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return nil, fmt.Errorf("Unknown device %s", hash)
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}
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devices.Devices[hash] = info
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}
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return info, nil
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}
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@ -224,7 +246,7 @@ func (devices *DeviceSet) registerDevice(id int, hash string, size uint64) (*Dev
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devices.Devices[hash] = info
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devices.devicesLock.Unlock()
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if err := devices.saveMetadata(); err != nil {
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if err := devices.saveMetadata(info); err != nil {
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// Try to remove unused device
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devices.devicesLock.Lock()
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delete(devices.Devices, hash)
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@ -259,9 +281,7 @@ func (devices *DeviceSet) createFilesystem(info *DevInfo) error {
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return nil
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}
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func (devices *DeviceSet) loadMetaData() error {
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utils.Debugf("loadMetadata()")
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defer utils.Debugf("loadMetadata END")
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func (devices *DeviceSet) initMetaData() error {
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_, _, _, params, err := getStatus(devices.getPoolName())
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if err != nil {
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utils.Debugf("\n--->Err: %s\n", err)
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@ -274,35 +294,64 @@ func (devices *DeviceSet) loadMetaData() error {
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}
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devices.NewTransactionId = devices.TransactionId
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jsonData, err := ioutil.ReadFile(devices.jsonFile())
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// Migrate old metadatafile
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jsonData, err := ioutil.ReadFile(devices.oldMetadataFile())
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if err != nil && !osIsNotExist(err) {
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utils.Debugf("\n--->Err: %s\n", err)
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return err
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}
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devices.MetaData.Devices = make(map[string]*DevInfo)
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if jsonData != nil {
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if err := json.Unmarshal(jsonData, &devices.MetaData); err != nil {
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m := MetaData{Devices: make(map[string]*DevInfo)}
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if err := json.Unmarshal(jsonData, &m); err != nil {
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utils.Debugf("\n--->Err: %s\n", err)
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return err
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}
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}
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for hash, d := range devices.Devices {
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d.Hash = hash
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d.devices = devices
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for hash, info := range m.Devices {
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info.Hash = hash
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// If the transaction id is larger than the actual one we lost the device due to some crash
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if d.TransactionId > devices.TransactionId {
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utils.Debugf("Removing lost device %s with id %d", hash, d.TransactionId)
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delete(devices.Devices, hash)
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// If the transaction id is larger than the actual one we lost the device due to some crash
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if info.TransactionId <= devices.TransactionId {
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devices.saveMetadata(info)
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}
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}
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if err := osRename(devices.oldMetadataFile(), devices.oldMetadataFile()+".migrated"); err != nil {
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return err
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}
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}
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return nil
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}
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func (devices *DeviceSet) loadMetadata(hash string) *DevInfo {
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info := &DevInfo{Hash: hash, devices: devices}
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jsonData, err := ioutil.ReadFile(devices.metadataFile(info))
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if err != nil {
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return nil
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}
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if err := json.Unmarshal(jsonData, &info); err != nil {
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return nil
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}
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fmt.Printf("Loaded metadata %v\n", info)
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// If the transaction id is larger than the actual one we lost the device due to some crash
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if info.TransactionId > devices.TransactionId {
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return nil
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}
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return info
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}
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func (devices *DeviceSet) setupBaseImage() error {
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oldInfo, _ := devices.lookupDevice("")
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utils.Debugf("oldInfo: %p", oldInfo)
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if oldInfo != nil && oldInfo.Initialized {
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return nil
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}
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@ -349,7 +398,7 @@ func (devices *DeviceSet) setupBaseImage() error {
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}
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info.Initialized = true
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if err = devices.saveMetadata(); err != nil {
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if err = devices.saveMetadata(info); err != nil {
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info.Initialized = false
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utils.Debugf("\n--->Err: %s\n", err)
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return err
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@ -457,29 +506,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
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func (devices *DeviceSet) initDevmapper(doInit bool) error {
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logInit(devices)
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// Make sure the sparse images exist in <root>/devicemapper/data and
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// <root>/devicemapper/metadata
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hasData := devices.hasImage("data")
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hasMetadata := devices.hasImage("metadata")
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if !doInit && !hasData {
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return errors.New("Loopback data file not found")
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}
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if !doInit && !hasMetadata {
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return errors.New("Loopback metadata file not found")
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}
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createdLoopback := !hasData || !hasMetadata
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data, err := devices.ensureImage("data", DefaultDataLoopbackSize)
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if err != nil {
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utils.Debugf("Error device ensureImage (data): %s\n", err)
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return err
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}
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metadata, err := devices.ensureImage("metadata", DefaultMetaDataLoopbackSize)
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if err != nil {
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utils.Debugf("Error device ensureImage (metadata): %s\n", err)
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if err := osMkdirAll(devices.metadataDir(), 0700); err != nil && !osIsExist(err) {
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return err
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}
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@ -512,10 +539,38 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
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// so we add this badhack to make sure it closes itself
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setCloseOnExec("/dev/mapper/control")
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// Make sure the sparse images exist in <root>/devicemapper/data and
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// <root>/devicemapper/metadata
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createdLoopback := false
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// If the pool doesn't exist, create it
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if info.Exists == 0 {
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utils.Debugf("Pool doesn't exist. Creating it.")
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hasData := devices.hasImage("data")
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hasMetadata := devices.hasImage("metadata")
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if !doInit && !hasData {
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return errors.New("Loopback data file not found")
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}
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if !doInit && !hasMetadata {
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return errors.New("Loopback metadata file not found")
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}
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createdLoopback = !hasData || !hasMetadata
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data, err := devices.ensureImage("data", DefaultDataLoopbackSize)
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if err != nil {
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utils.Debugf("Error device ensureImage (data): %s\n", err)
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return err
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}
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metadata, err := devices.ensureImage("metadata", DefaultMetaDataLoopbackSize)
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if err != nil {
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utils.Debugf("Error device ensureImage (metadata): %s\n", err)
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return err
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}
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dataFile, err := attachLoopDevice(data)
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if err != nil {
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utils.Debugf("\n--->Err: %s\n", err)
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@ -537,9 +592,9 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
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}
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// If we didn't just create the data or metadata image, we need to
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// load the metadata from the existing file.
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// load the transaction id and migrate old metadata
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if !createdLoopback {
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if err = devices.loadMetaData(); err != nil {
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if err = devices.initMetaData(); err != nil {
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utils.Debugf("\n--->Err: %s\n", err)
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return err
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}
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@ -608,14 +663,6 @@ func (devices *DeviceSet) deleteDevice(info *DevInfo) error {
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}
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}
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if info.Initialized {
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info.Initialized = false
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if err := devices.saveMetadata(); err != nil {
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utils.Debugf("Error saving meta data: %s\n", err)
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return err
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}
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}
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if err := deleteDevice(devices.getPoolDevName(), info.DeviceId); err != nil {
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utils.Debugf("Error deleting device: %s\n", err)
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return err
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@ -626,11 +673,11 @@ func (devices *DeviceSet) deleteDevice(info *DevInfo) error {
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delete(devices.Devices, info.Hash)
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devices.devicesLock.Unlock()
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if err := devices.saveMetadata(); err != nil {
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if err := devices.removeMetadata(info); err != nil {
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devices.devicesLock.Lock()
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devices.Devices[info.Hash] = info
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devices.devicesLock.Unlock()
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utils.Debugf("Error saving meta data: %s\n", err)
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utils.Debugf("Error removing meta data: %s\n", err)
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return err
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}
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@ -873,7 +920,7 @@ func (devices *DeviceSet) MountDevice(hash, path string, mountLabel string) erro
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info.mountCount = 1
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info.mountPath = path
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return devices.setInitialized(info)
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return nil
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}
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func (devices *DeviceSet) UnmountDevice(hash string) error {
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@ -924,14 +971,6 @@ func (devices *DeviceSet) HasDevice(hash string) bool {
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return info != nil
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}
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func (devices *DeviceSet) HasInitializedDevice(hash string) bool {
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devices.Lock()
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defer devices.Unlock()
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info, _ := devices.lookupDevice(hash)
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return info != nil && info.Initialized
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}
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func (devices *DeviceSet) HasActivatedDevice(hash string) bool {
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info, _ := devices.lookupDevice(hash)
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if info == nil {
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@ -948,17 +987,6 @@ func (devices *DeviceSet) HasActivatedDevice(hash string) bool {
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return devinfo != nil && devinfo.Exists != 0
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}
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func (devices *DeviceSet) setInitialized(info *DevInfo) error {
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info.Initialized = true
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if err := devices.saveMetadata(); err != nil {
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info.Initialized = false
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utils.Debugf("\n--->Err: %s\n", err)
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return err
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}
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return nil
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}
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func (devices *DeviceSet) List() []string {
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devices.Lock()
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defer devices.Unlock()
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@ -820,10 +820,6 @@ func TestGetReturnsValidDevice(t *testing.T) {
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if !d.HasActivatedDevice("1") {
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t.Fatalf("Expected id 1 to be activated")
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}
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if !d.HasInitializedDevice("1") {
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t.Fatalf("Expected id 1 to be initialized")
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}
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}
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func TestDriverGetSize(t *testing.T) {
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