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b95c560fdd
We already have some kind of refcounting in DeviceSet, this fleshes it out to allow it to completely subsume the refcounting in devmapper.Driver. This allows us to drop the double refcounting, and the locking inside devmapper.Driver. This, in particular the locking simplification will make it easier in the future to parallelize the device mapper. Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
126 lines
3 KiB
Go
126 lines
3 KiB
Go
// +build linux,amd64
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package devmapper
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import (
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"fmt"
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"github.com/dotcloud/docker/graphdriver"
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"github.com/dotcloud/docker/utils"
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"io/ioutil"
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"path"
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)
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func init() {
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graphdriver.Register("devicemapper", Init)
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}
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// Placeholder interfaces, to be replaced
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// at integration.
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// End of placeholder interfaces.
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type Driver struct {
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*DeviceSet
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home string
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}
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var Init = func(home string) (graphdriver.Driver, error) {
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deviceSet, err := NewDeviceSet(home, true)
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if err != nil {
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return nil, err
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}
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d := &Driver{
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DeviceSet: deviceSet,
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home: home,
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}
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return d, nil
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}
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func (d *Driver) String() string {
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return "devicemapper"
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}
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func (d *Driver) Status() [][2]string {
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s := d.DeviceSet.Status()
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status := [][2]string{
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{"Pool Name", s.PoolName},
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{"Data file", s.DataLoopback},
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{"Metadata file", s.MetadataLoopback},
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{"Data Space Used", fmt.Sprintf("%.1f Mb", float64(s.Data.Used)/(1024*1024))},
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{"Data Space Total", fmt.Sprintf("%.1f Mb", float64(s.Data.Total)/(1024*1024))},
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{"Metadata Space Used", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Used)/(1024*1024))},
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{"Metadata Space Total", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Total)/(1024*1024))},
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}
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return status
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}
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func (d *Driver) Cleanup() error {
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return d.DeviceSet.Shutdown()
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}
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func (d *Driver) Create(id, parent string) error {
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if err := d.DeviceSet.AddDevice(id, parent); err != nil {
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return err
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}
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mp := path.Join(d.home, "mnt", id)
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if err := d.mount(id, mp); err != nil {
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return err
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}
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if err := osMkdirAll(path.Join(mp, "rootfs"), 0755); err != nil && !osIsExist(err) {
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return err
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}
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// Create an "id" file with the container/image id in it to help reconscruct this in case
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// of later problems
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if err := ioutil.WriteFile(path.Join(mp, "id"), []byte(id), 0600); err != nil {
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return err
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}
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// We float this reference so that the next Get call can
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// steal it, so we don't have to unmount
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if err := d.DeviceSet.UnmountDevice(id, UnmountFloat); err != nil {
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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 (d *Driver) Remove(id string) error {
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// Sink the float from create in case no Get() call was made
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if err := d.DeviceSet.UnmountDevice(id, UnmountSink); err != nil {
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return err
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}
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// This assumes the device has been properly Get/Put:ed and thus is unmounted
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return d.DeviceSet.DeleteDevice(id)
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}
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func (d *Driver) Get(id string) (string, error) {
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mp := path.Join(d.home, "mnt", id)
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if err := d.mount(id, mp); err != nil {
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return "", err
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}
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return path.Join(mp, "rootfs"), nil
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}
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func (d *Driver) Put(id string) {
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if err := d.DeviceSet.UnmountDevice(id, UnmountRegular); err != nil {
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utils.Errorf("Warning: error unmounting device %s: %s\n", id, err)
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}
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}
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func (d *Driver) mount(id, mountPoint string) error {
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// Create the target directories if they don't exist
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if err := osMkdirAll(mountPoint, 0755); err != nil && !osIsExist(err) {
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return err
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}
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// Mount the device
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return d.DeviceSet.MountDevice(id, mountPoint)
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}
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func (d *Driver) Exists(id string) bool {
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return d.Devices[id] != nil
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}
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