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devmapper: Add lock to protext Devices map

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Currently access to the Devices map is serialized by the main
DeviceSet lock, but we need to access it outside that lock, so we
add a separate lock for this and grab that everywhere we modify
or read the map.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Upstream-commit: 70826e8b3fee27b971852aad89053507c6866d3e
Component: engine
This commit is contained in:
Alexander Larsson
2014-04-01 11:05:30 +02:00
parent 1544c3baed
commit bd0bcefa7f
1 changed files with 26 additions and 1 deletions
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27
components/engine/runtime/graphdriver/devmapper/deviceset.go
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@@ -51,7 +51,8 @@ type DevInfo struct {
}
type MetaData struct {
Devices map[string]*DevInfo `json:devices`
Devices map[string]*DevInfo `json:devices`
devicesLock sync.Mutex `json:"-"` // Protects all read/writes to Devices map
}
type DeviceSet struct {
@@ -179,7 +180,9 @@ func (devices *DeviceSet) allocateTransactionId() uint64 {
}
func (devices *DeviceSet) saveMetadata() error {
devices.devicesLock.Lock()
jsonData, err := json.Marshal(devices.MetaData)
devices.devicesLock.Unlock()
if err != nil {
return fmt.Errorf("Error encoding metadata to json: %s", err)
}
@@ -215,6 +218,8 @@ func (devices *DeviceSet) saveMetadata() error {
}
func (devices *DeviceSet) lookupDevice(hash string) (*DevInfo, error) {
devices.devicesLock.Lock()
defer devices.devicesLock.Unlock()
info := devices.Devices[hash]
if info == nil {
return nil, fmt.Errorf("Unknown device %s", hash)
@@ -233,10 +238,15 @@ func (devices *DeviceSet) registerDevice(id int, hash string, size uint64) (*Dev
devices: devices,
}
devices.devicesLock.Lock()
devices.Devices[hash] = info
devices.devicesLock.Unlock()
if err := devices.saveMetadata(); err != nil {
// Try to remove unused device
devices.devicesLock.Lock()
delete(devices.Devices, hash)
devices.devicesLock.Unlock()
return nil, err
}
@@ -632,10 +642,14 @@ func (devices *DeviceSet) deleteDevice(info *DevInfo) error {
}
devices.allocateTransactionId()
devices.devicesLock.Lock()
delete(devices.Devices, info.Hash)
devices.devicesLock.Unlock()
if err := devices.saveMetadata(); err != nil {
devices.devicesLock.Lock()
devices.Devices[info.Hash] = info
devices.devicesLock.Unlock()
utils.Debugf("Error saving meta data: %s\n", err)
return err
}
@@ -795,7 +809,15 @@ func (devices *DeviceSet) Shutdown() error {
utils.Debugf("[devmapper] Shutting down DeviceSet: %s", devices.root)
defer utils.Debugf("[deviceset %s] shutdown END", devices.devicePrefix)
var devs []*DevInfo
devices.devicesLock.Lock()
for _, info := range devices.Devices {
devs = append(devs, info)
}
devices.devicesLock.Unlock()
for _, info := range devs {
info.lock.Lock()
if info.mountCount > 0 {
// We use MNT_DETACH here in case it is still busy in some running
@@ -979,12 +1001,15 @@ func (devices *DeviceSet) List() []string {
devices.Lock()
defer devices.Unlock()
devices.devicesLock.Lock()
ids := make([]string, len(devices.Devices))
i := 0
for k := range devices.Devices {
ids[i] = k
i++
}
devices.devicesLock.Unlock()
return ids
}