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driver.go
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driver.go
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//go:build linux
// +build linux
package devmapper // import "github.com/docker/docker/daemon/graphdriver/devmapper"
import (
"fmt"
"os"
"path"
"strconv"
"github.com/docker/docker/daemon/graphdriver"
"github.com/docker/docker/pkg/devicemapper"
"github.com/docker/docker/pkg/idtools"
units "github.com/docker/go-units"
"github.com/moby/locker"
"github.com/moby/sys/mount"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
func init() {
graphdriver.Register("devicemapper", Init)
}
// Driver contains the device set mounted and the home directory
type Driver struct {
*DeviceSet
home string
ctr *graphdriver.RefCounter
locker *locker.Locker
}
// Init creates a driver with the given home and the set of options.
func Init(home string, options []string, idMap idtools.IdentityMapping) (graphdriver.Driver, error) {
deviceSet, err := NewDeviceSet(home, true, options, idMap)
if err != nil {
return nil, err
}
d := &Driver{
DeviceSet: deviceSet,
home: home,
ctr: graphdriver.NewRefCounter(graphdriver.NewDefaultChecker()),
locker: locker.New(),
}
return graphdriver.NewNaiveDiffDriver(d, d.idMap), nil
}
func (d *Driver) String() string {
return "devicemapper"
}
// Status returns the status about the driver in a printable format.
// Information returned contains Pool Name, Data File, Metadata file, disk usage by
// the data and metadata, etc.
func (d *Driver) Status() [][2]string {
s := d.DeviceSet.Status()
status := [][2]string{
{"Pool Name", s.PoolName},
{"Pool Blocksize", units.HumanSize(float64(s.SectorSize))},
{"Base Device Size", units.HumanSize(float64(s.BaseDeviceSize))},
{"Backing Filesystem", s.BaseDeviceFS},
{"Udev Sync Supported", fmt.Sprintf("%v", s.UdevSyncSupported)},
}
if len(s.DataFile) > 0 {
status = append(status, [2]string{"Data file", s.DataFile})
}
if len(s.MetadataFile) > 0 {
status = append(status, [2]string{"Metadata file", s.MetadataFile})
}
if len(s.DataLoopback) > 0 {
status = append(status, [2]string{"Data loop file", s.DataLoopback})
}
if len(s.MetadataLoopback) > 0 {
status = append(status, [2]string{"Metadata loop file", s.MetadataLoopback})
}
status = append(status, [][2]string{
{"Data Space Used", units.HumanSize(float64(s.Data.Used))},
{"Data Space Total", units.HumanSize(float64(s.Data.Total))},
{"Data Space Available", units.HumanSize(float64(s.Data.Available))},
{"Metadata Space Used", units.HumanSize(float64(s.Metadata.Used))},
{"Metadata Space Total", units.HumanSize(float64(s.Metadata.Total))},
{"Metadata Space Available", units.HumanSize(float64(s.Metadata.Available))},
{"Thin Pool Minimum Free Space", units.HumanSize(float64(s.MinFreeSpace))},
{"Deferred Removal Enabled", fmt.Sprintf("%v", s.DeferredRemoveEnabled)},
{"Deferred Deletion Enabled", fmt.Sprintf("%v", s.DeferredDeleteEnabled)},
{"Deferred Deleted Device Count", fmt.Sprintf("%v", s.DeferredDeletedDeviceCount)},
}...)
if vStr, err := devicemapper.GetLibraryVersion(); err == nil {
status = append(status, [2]string{"Library Version", vStr})
}
return status
}
// GetMetadata returns a map of information about the device.
func (d *Driver) GetMetadata(id string) (map[string]string, error) {
m, err := d.DeviceSet.exportDeviceMetadata(id)
if err != nil {
return nil, err
}
metadata := make(map[string]string)
metadata["DeviceId"] = strconv.Itoa(m.deviceID)
metadata["DeviceSize"] = strconv.FormatUint(m.deviceSize, 10)
metadata["DeviceName"] = m.deviceName
return metadata, nil
}
// Cleanup unmounts a device.
func (d *Driver) Cleanup() error {
err := d.DeviceSet.Shutdown(d.home)
umountErr := mount.RecursiveUnmount(d.home)
// in case we have two errors, prefer the one from Shutdown()
if err != nil {
return err
}
return umountErr
}
// CreateReadWrite creates a layer that is writable for use as a container
// file system.
func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
return d.Create(id, parent, opts)
}
// Create adds a device with a given id and the parent.
func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) error {
var storageOpt map[string]string
if opts != nil {
storageOpt = opts.StorageOpt
}
return d.DeviceSet.AddDevice(id, parent, storageOpt)
}
// Remove removes a device with a given id, unmounts the filesystem, and removes the mount point.
func (d *Driver) Remove(id string) error {
d.locker.Lock(id)
defer d.locker.Unlock(id)
if !d.DeviceSet.HasDevice(id) {
// Consider removing a non-existing device a no-op
// This is useful to be able to progress on container removal
// if the underlying device has gone away due to earlier errors
return nil
}
// This assumes the device has been properly Get/Put:ed and thus is unmounted
if err := d.DeviceSet.DeleteDevice(id, false); err != nil {
return fmt.Errorf("failed to remove device %s: %v", id, err)
}
// Most probably the mount point is already removed on Put()
// (see DeviceSet.UnmountDevice()), but just in case it was not
// let's try to remove it here as well, ignoring errors as
// an older kernel can return EBUSY if e.g. the mount was leaked
// to other mount namespaces. A failure to remove the container's
// mount point is not important and should not be treated
// as a failure to remove the container.
mp := path.Join(d.home, "mnt", id)
err := unix.Rmdir(mp)
if err != nil && !os.IsNotExist(err) {
logrus.WithField("storage-driver", "devicemapper").Warnf("unable to remove mount point %q: %s", mp, err)
}
return nil
}
// Get mounts a device with given id into the root filesystem
func (d *Driver) Get(id, mountLabel string) (string, error) {
d.locker.Lock(id)
defer d.locker.Unlock(id)
mp := path.Join(d.home, "mnt", id)
rootFs := path.Join(mp, "rootfs")
if count := d.ctr.Increment(mp); count > 1 {
return rootFs, nil
}
root := d.idMap.RootPair()
// Create the target directories if they don't exist
if err := idtools.MkdirAllAndChown(path.Join(d.home, "mnt"), 0755, root); err != nil {
d.ctr.Decrement(mp)
return "", err
}
if err := idtools.MkdirAndChown(mp, 0755, root); err != nil && !os.IsExist(err) {
d.ctr.Decrement(mp)
return "", err
}
// Mount the device
if err := d.DeviceSet.MountDevice(id, mp, mountLabel); err != nil {
d.ctr.Decrement(mp)
return "", err
}
if err := idtools.MkdirAllAndChown(rootFs, 0755, root); err != nil {
d.ctr.Decrement(mp)
d.DeviceSet.UnmountDevice(id, mp)
return "", err
}
idFile := path.Join(mp, "id")
if _, err := os.Stat(idFile); err != nil && os.IsNotExist(err) {
// Create an "id" file with the container/image id in it to help reconstruct this in case
// of later problems
if err := os.WriteFile(idFile, []byte(id), 0600); err != nil {
d.ctr.Decrement(mp)
d.DeviceSet.UnmountDevice(id, mp)
return "", err
}
}
return rootFs, nil
}
// Put unmounts a device and removes it.
func (d *Driver) Put(id string) error {
d.locker.Lock(id)
defer d.locker.Unlock(id)
mp := path.Join(d.home, "mnt", id)
if count := d.ctr.Decrement(mp); count > 0 {
return nil
}
err := d.DeviceSet.UnmountDevice(id, mp)
if err != nil {
logrus.WithField("storage-driver", "devicemapper").Errorf("Error unmounting device %s: %v", id, err)
}
return err
}
// Exists checks to see if the device exists.
func (d *Driver) Exists(id string) bool {
return d.DeviceSet.HasDevice(id)
}