зеркало из https://github.com/microsoft/docker.git
devmapper: Get rid of metaData.devicesLock
Right now we seem to have 3 locks. - devinfo.lock This is a per device lock - metaData.devicesLock This is supposedely protecting map of devices. - Global DeviceSet lock This is protecting map of devices as well as serializing calls to libdevmapper. Semantics of per devices lock and global deviceset lock seem to be very clear. Even ordering between these two locks has been defined properly. What is not clear is the need and ordering of metaData.devicesLock. Looks like this lock is not necessary and global DeviceSet lock should be used to protect map of devices as it is part of DeviceSet. This patchset gets rid of metaData.devicesLock and instead uses DeviceSet lock to protect map of devices. Also at couple of places during initialization takes devices.Lock(). That is not strictly necessary as there is supposed to be one thread of execution during initializaiton. Still it makes the code clearer. I think this makes code more clear and easier to understand and easier to make further changes. Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
Vivek Goyal
Родитель
73f8b46d84
Коммит
289145ecc6
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@ -76,14 +76,13 @@ type devInfo struct {
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}
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type metaData struct {
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Devices map[string]*devInfo `json:"Devices"`
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devicesLock sync.Mutex // Protects all read/writes to Devices map
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Devices map[string]*devInfo `json:"Devices"`
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}
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// DeviceSet holds information about list of devices
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type DeviceSet struct {
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metaData `json:"-"`
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sync.Mutex `json:"-"` // Protects Devices map and serializes calls into libdevmapper
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sync.Mutex `json:"-"` // Protects all fields of DeviceSet and serializes calls into libdevmapper
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root string
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devicePrefix string
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TransactionID uint64 `json:"-"`
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@ -355,9 +354,8 @@ func (devices *DeviceSet) isDeviceIDFree(deviceID int) bool {
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return true
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}
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// Should be called with devices.Lock() held.
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func (devices *DeviceSet) lookupDevice(hash string) (*devInfo, error) {
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devices.devicesLock.Lock()
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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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info = devices.loadMetadata(hash)
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@ -370,6 +368,13 @@ func (devices *DeviceSet) lookupDevice(hash string) (*devInfo, error) {
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return info, nil
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}
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func (devices *DeviceSet) lookupDeviceWithLock(hash string) (*devInfo, error) {
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devices.Lock()
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defer devices.Unlock()
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info, err := devices.lookupDevice(hash)
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return info, err
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}
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func (devices *DeviceSet) deviceFileWalkFunction(path string, finfo os.FileInfo) error {
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// Skip some of the meta files which are not device files.
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@ -405,10 +410,7 @@ func (devices *DeviceSet) deviceFileWalkFunction(path string, finfo os.FileInfo)
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return fmt.Errorf("Error loading device metadata file %s", hash)
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}
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devices.Lock()
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devices.markDeviceIDUsed(dinfo.DeviceID)
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devices.Unlock()
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logrus.Debugf("Added deviceID=%d to DeviceIDMap", dinfo.DeviceID)
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return nil
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}
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@ -434,6 +436,7 @@ func (devices *DeviceSet) constructDeviceIDMap() error {
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return filepath.Walk(devices.metadataDir(), scan)
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}
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// Should be called with devices.Lock() held.
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func (devices *DeviceSet) unregisterDevice(id int, hash string) error {
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logrus.Debugf("unregisterDevice(%v, %v)", id, hash)
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info := &devInfo{
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@ -441,9 +444,7 @@ func (devices *DeviceSet) unregisterDevice(id int, hash string) error {
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DeviceID: id,
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}
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devices.devicesLock.Lock()
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delete(devices.Devices, hash)
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devices.devicesLock.Unlock()
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if err := devices.removeMetadata(info); err != nil {
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logrus.Debugf("Error removing metadata: %s", err)
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@ -453,6 +454,7 @@ func (devices *DeviceSet) unregisterDevice(id int, hash string) error {
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return nil
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}
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// Should be called with devices.Lock() held.
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func (devices *DeviceSet) registerDevice(id int, hash string, size uint64, transactionID uint64) (*devInfo, error) {
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logrus.Debugf("registerDevice(%v, %v)", id, hash)
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info := &devInfo{
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@ -464,15 +466,11 @@ func (devices *DeviceSet) registerDevice(id int, hash string, size uint64, trans
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devices: devices,
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}
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devices.devicesLock.Lock()
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devices.Devices[hash] = info
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devices.devicesLock.Unlock()
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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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devices.devicesLock.Unlock()
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return nil, err
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}
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@ -556,6 +554,9 @@ func (devices *DeviceSet) migrateOldMetaData() error {
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}
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func (devices *DeviceSet) initMetaData() error {
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devices.Lock()
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defer devices.Unlock()
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if err := devices.migrateOldMetaData(); err != nil {
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return err
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}
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@ -596,6 +597,9 @@ func (devices *DeviceSet) getNextFreeDeviceID() (int, error) {
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}
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func (devices *DeviceSet) createRegisterDevice(hash string) (*devInfo, error) {
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devices.Lock()
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defer devices.Unlock()
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deviceID, err := devices.getNextFreeDeviceID()
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if err != nil {
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return nil, err
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@ -774,7 +778,7 @@ func (devices *DeviceSet) saveBaseDeviceUUID(baseInfo *devInfo) error {
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}
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func (devices *DeviceSet) setupBaseImage() error {
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oldInfo, _ := devices.lookupDevice("")
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oldInfo, _ := devices.lookupDeviceWithLock("")
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if oldInfo != nil && oldInfo.Initialized {
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// If BaseDeviceUUID is nil (upgrade case), save it and
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// return success.
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@ -1443,7 +1447,7 @@ func (devices *DeviceSet) AddDevice(hash, baseHash string) error {
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logrus.Debugf("[deviceset] AddDevice(hash=%s basehash=%s)", hash, baseHash)
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defer logrus.Debugf("[deviceset] AddDevice(hash=%s basehash=%s) END", hash, baseHash)
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baseInfo, err := devices.lookupDevice(baseHash)
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baseInfo, err := devices.lookupDeviceWithLock(baseHash)
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if err != nil {
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return err
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}
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@ -1465,6 +1469,7 @@ func (devices *DeviceSet) AddDevice(hash, baseHash string) error {
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return nil
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}
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// Should be called with devices.Lock() held.
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func (devices *DeviceSet) deleteDevice(info *devInfo) error {
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if devices.doBlkDiscard {
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// This is a workaround for the kernel not discarding block so
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@ -1508,7 +1513,7 @@ func (devices *DeviceSet) deleteDevice(info *devInfo) error {
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// DeleteDevice deletes a device from the hash.
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func (devices *DeviceSet) DeleteDevice(hash string) error {
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info, err := devices.lookupDevice(hash)
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info, err := devices.lookupDeviceWithLock(hash)
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if err != nil {
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return err
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}
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@ -1651,11 +1656,11 @@ func (devices *DeviceSet) Shutdown() error {
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var devs []*devInfo
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devices.devicesLock.Lock()
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devices.Lock()
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for _, info := range devices.Devices {
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devs = append(devs, info)
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}
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devices.devicesLock.Unlock()
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devices.Unlock()
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for _, info := range devs {
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info.lock.Lock()
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@ -1676,7 +1681,7 @@ func (devices *DeviceSet) Shutdown() error {
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info.lock.Unlock()
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}
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info, _ := devices.lookupDevice("")
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info, _ := devices.lookupDeviceWithLock("")
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if info != nil {
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info.lock.Lock()
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devices.Lock()
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@ -1702,7 +1707,7 @@ func (devices *DeviceSet) Shutdown() error {
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// MountDevice mounts the device if not already mounted.
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func (devices *DeviceSet) MountDevice(hash, path, mountLabel string) error {
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info, err := devices.lookupDevice(hash)
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info, err := devices.lookupDeviceWithLock(hash)
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if err != nil {
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return err
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}
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@ -1756,7 +1761,7 @@ func (devices *DeviceSet) UnmountDevice(hash string) error {
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logrus.Debugf("[devmapper] UnmountDevice(hash=%s)", hash)
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defer logrus.Debugf("[devmapper] UnmountDevice(hash=%s) END", hash)
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info, err := devices.lookupDevice(hash)
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info, err := devices.lookupDeviceWithLock(hash)
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if err != nil {
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return err
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}
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@ -1793,10 +1798,7 @@ func (devices *DeviceSet) UnmountDevice(hash string) error {
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// HasDevice returns true if the device metadata exists.
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func (devices *DeviceSet) HasDevice(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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info, _ := devices.lookupDeviceWithLock(hash)
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return info != nil
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}
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@ -1805,15 +1807,12 @@ func (devices *DeviceSet) List() []string {
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devices.Lock()
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defer devices.Unlock()
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devices.devicesLock.Lock()
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ids := make([]string, len(devices.Devices))
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i := 0
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for k := range devices.Devices {
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ids[i] = k
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i++
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}
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devices.devicesLock.Unlock()
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return ids
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}
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@ -1831,7 +1830,7 @@ func (devices *DeviceSet) deviceStatus(devName string) (sizeInSectors, mappedSec
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// GetDeviceStatus provides size, mapped sectors
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func (devices *DeviceSet) GetDeviceStatus(hash string) (*DevStatus, error) {
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info, err := devices.lookupDevice(hash)
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info, err := devices.lookupDeviceWithLock(hash)
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if err != nil {
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return nil, err
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}
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@ -1957,7 +1956,7 @@ func (devices *DeviceSet) Status() *Status {
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// Status returns the current status of this deviceset
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func (devices *DeviceSet) exportDeviceMetadata(hash string) (*deviceMetadata, error) {
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info, err := devices.lookupDevice(hash)
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info, err := devices.lookupDeviceWithLock(hash)
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if err != nil {
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return nil, err
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}
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