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devmapper: Simplify thin pool device id allocation

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Instead of globally keeping track of the free device ids we just
start from 0 each run and handle EEXIST error and try the next one.

This way we don't need any global state for the device ids, which
means we can read device metadata lazily. This is important for
multi-process use of the backend.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
This commit is contained in:
Alexander Larsson 2014-04-24 22:36:45 +02:00
parent 586a511cb5
commit f26203cf54
3 changed files with 73 additions and 52 deletions
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27
daemon/graphdriver/devmapper/deviceset.go
View file

@ -60,7 +60,7 @@ type DeviceSet struct {
devicePrefix string
TransactionId uint64
NewTransactionId uint64
nextFreeDevice int
nextDeviceId int
}
type DiskUsage struct {
@ -156,13 +156,6 @@ func (devices *DeviceSet) ensureImage(name string, size int64) (string, error) {
return filename, nil
}
func (devices *DeviceSet) allocateDeviceId() int {
// TODO: Add smarter reuse of deleted devices
id := devices.nextFreeDevice
devices.nextFreeDevice = devices.nextFreeDevice + 1
return id
}
func (devices *DeviceSet) allocateTransactionId() uint64 {
devices.NewTransactionId = devices.NewTransactionId + 1
return devices.NewTransactionId
@ -299,10 +292,6 @@ func (devices *DeviceSet) loadMetaData() error {
d.Hash = hash
d.devices = devices
if d.DeviceId >= devices.nextFreeDevice {
devices.nextFreeDevice = d.DeviceId + 1
}
// If the transaction id is larger than the actual one we lost the device due to some crash
if d.TransactionId > devices.TransactionId {
utils.Debugf("Removing lost device %s with id %d", hash, d.TransactionId)
@ -328,14 +317,17 @@ func (devices *DeviceSet) setupBaseImage() error {
utils.Debugf("Initializing base device-manager snapshot")
id := devices.allocateDeviceId()
id := devices.nextDeviceId
// Create initial device
if err := createDevice(devices.getPoolDevName(), id); err != nil {
if err := createDevice(devices.getPoolDevName(), &id); err != nil {
utils.Debugf("\n--->Err: %s\n", err)
return err
}
// Ids are 24bit, so wrap around
devices.nextDeviceId = (id + 1) & 0xffffff
utils.Debugf("Registering base device (id %v) with FS size %v", id, DefaultBaseFsSize)
info, err := devices.registerDevice(id, "", DefaultBaseFsSize)
if err != nil {
@ -580,13 +572,16 @@ func (devices *DeviceSet) AddDevice(hash, baseHash string) error {
return fmt.Errorf("device %s already exists", hash)
}
deviceId := devices.allocateDeviceId()
deviceId := devices.nextDeviceId
if err := createSnapDevice(devices.getPoolDevName(), deviceId, baseInfo.Name(), baseInfo.DeviceId); err != nil {
if err := createSnapDevice(devices.getPoolDevName(), &deviceId, baseInfo.Name(), baseInfo.DeviceId); err != nil {
utils.Debugf("Error creating snap device: %s\n", err)
return err
}
// Ids are 24bit, so wrap around
devices.nextDeviceId = (deviceId + 1) & 0xffffff
if _, err := devices.registerDevice(deviceId, hash, baseInfo.Size); err != nil {
deleteDevice(devices.getPoolDevName(), deviceId)
utils.Debugf("Error registering device: %s\n", err)

94
daemon/graphdriver/devmapper/devmapper.go
View file

@ -64,7 +64,8 @@ var (
ErrLoopbackSetCapacity = errors.New("Unable set loopback capacity")
ErrBusy = errors.New("Device is Busy")
dmSawBusy bool
dmSawBusy bool
dmSawExist bool
)
type (
@ -467,23 +468,33 @@ func resumeDevice(name string) error {
return nil
}
func createDevice(poolName string, deviceId int) error {
utils.Debugf("[devmapper] createDevice(poolName=%v, deviceId=%v)", poolName, deviceId)
task, err := createTask(DeviceTargetMsg, poolName)
if task == nil {
return err
}
func createDevice(poolName string, deviceId *int) error {
utils.Debugf("[devmapper] createDevice(poolName=%v, deviceId=%v)", poolName, *deviceId)
if err := task.SetSector(0); err != nil {
return fmt.Errorf("Can't set sector")
}
for {
task, err := createTask(DeviceTargetMsg, poolName)
if task == nil {
return err
}
if err := task.SetMessage(fmt.Sprintf("create_thin %d", deviceId)); err != nil {
return fmt.Errorf("Can't set message")
}
if err := task.SetSector(0); err != nil {
return fmt.Errorf("Can't set sector")
}
if err := task.Run(); err != nil {
return fmt.Errorf("Error running createDevice")
if err := task.SetMessage(fmt.Sprintf("create_thin %d", *deviceId)); err != nil {
return fmt.Errorf("Can't set message")
}
dmSawExist = false
if err := task.Run(); err != nil {
if dmSawExist {
// Already exists, try next id
*deviceId++
continue
}
return fmt.Errorf("Error running createDevice")
}
break
}
return nil
}
@ -553,7 +564,7 @@ func activateDevice(poolName string, name string, deviceId int, size uint64) err
return nil
}
func createSnapDevice(poolName string, deviceId int, baseName string, baseDeviceId int) error {
func createSnapDevice(poolName string, deviceId *int, baseName string, baseDeviceId int) error {
devinfo, _ := getInfo(baseName)
doSuspend := devinfo != nil && devinfo.Exists != 0
@ -563,33 +574,44 @@ func createSnapDevice(poolName string, deviceId int, baseName string, baseDevice
}
}
task, err := createTask(DeviceTargetMsg, poolName)
if task == nil {
if doSuspend {
resumeDevice(baseName)
for {
task, err := createTask(DeviceTargetMsg, poolName)
if task == nil {
if doSuspend {
resumeDevice(baseName)
}
return err
}
return err
}
if err := task.SetSector(0); err != nil {
if doSuspend {
resumeDevice(baseName)
if err := task.SetSector(0); err != nil {
if doSuspend {
resumeDevice(baseName)
}
return fmt.Errorf("Can't set sector")
}
return fmt.Errorf("Can't set sector")
}
if err := task.SetMessage(fmt.Sprintf("create_snap %d %d", deviceId, baseDeviceId)); err != nil {
if doSuspend {
resumeDevice(baseName)
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")
}
return fmt.Errorf("Can't set message")
}
if err := task.Run(); err != nil {
if doSuspend {
resumeDevice(baseName)
dmSawExist = false
if err := task.Run(); err != nil {
if dmSawExist {
// Already exists, try next id
*deviceId++
continue
}
if doSuspend {
resumeDevice(baseName)
}
return fmt.Errorf("Error running DeviceCreate (createSnapDevice)")
}
return fmt.Errorf("Error running DeviceCreate (createSnapDevice)")
break
}
if doSuspend {

4
daemon/graphdriver/devmapper/devmapper_log.go
View file

@ -18,6 +18,10 @@ func DevmapperLogCallback(level C.int, file *C.char, line C.int, dm_errno_or_cla
if strings.Contains(msg, "busy") {
dmSawBusy = true
}
if strings.Contains(msg, "File exists") {
dmSawExist = true
}
}
if dmLogger != nil {