mirror of
https://github.com/moby/moby.git
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557 lines
13 KiB
Go
557 lines
13 KiB
Go
// +build linux
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/*
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aufs driver directory structure
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.
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├── layers // Metadata of layers
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│ ├── 1
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│ ├── 2
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│ └── 3
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├── diff // Content of the layer
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│ ├── 1 // Contains layers that need to be mounted for the id
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│ ├── 2
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│ └── 3
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└── mnt // Mount points for the rw layers to be mounted
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├── 1
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├── 2
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└── 3
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*/
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package aufs
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import (
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"bufio"
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"fmt"
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"io/ioutil"
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"os"
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"os/exec"
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"path"
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"strings"
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"sync"
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"syscall"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/daemon/graphdriver"
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"github.com/docker/docker/pkg/archive"
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"github.com/docker/docker/pkg/chrootarchive"
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"github.com/docker/docker/pkg/directory"
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"github.com/docker/docker/pkg/idtools"
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mountpk "github.com/docker/docker/pkg/mount"
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"github.com/docker/docker/pkg/stringid"
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"github.com/opencontainers/runc/libcontainer/label"
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)
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var (
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// ErrAufsNotSupported is returned if aufs is not supported by the host.
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ErrAufsNotSupported = fmt.Errorf("AUFS was not found in /proc/filesystems")
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incompatibleFsMagic = []graphdriver.FsMagic{
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graphdriver.FsMagicBtrfs,
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graphdriver.FsMagicAufs,
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}
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backingFs = "<unknown>"
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enableDirpermLock sync.Once
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enableDirperm bool
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)
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func init() {
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graphdriver.Register("aufs", Init)
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}
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type data struct {
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referenceCount int
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path string
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}
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// Driver contains information about the filesystem mounted.
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// root of the filesystem
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// sync.Mutex to protect against concurrent modifications
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// active maps mount id to the count
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type Driver struct {
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root string
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uidMaps []idtools.IDMap
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gidMaps []idtools.IDMap
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sync.Mutex // Protects concurrent modification to active
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active map[string]*data
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}
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// Init returns a new AUFS driver.
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// An error is returned if AUFS is not supported.
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func Init(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
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// Try to load the aufs kernel module
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if err := supportsAufs(); err != nil {
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return nil, graphdriver.ErrNotSupported
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}
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fsMagic, err := graphdriver.GetFSMagic(root)
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if err != nil {
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return nil, err
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}
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if fsName, ok := graphdriver.FsNames[fsMagic]; ok {
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backingFs = fsName
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}
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for _, magic := range incompatibleFsMagic {
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if fsMagic == magic {
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return nil, graphdriver.ErrIncompatibleFS
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}
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}
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paths := []string{
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"mnt",
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"diff",
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"layers",
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}
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a := &Driver{
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root: root,
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active: make(map[string]*data),
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uidMaps: uidMaps,
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gidMaps: gidMaps,
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}
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rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)
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if err != nil {
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return nil, err
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}
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// Create the root aufs driver dir and return
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// if it already exists
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// If not populate the dir structure
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if err := idtools.MkdirAllAs(root, 0700, rootUID, rootGID); err != nil {
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if os.IsExist(err) {
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return a, nil
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}
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return nil, err
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}
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if err := mountpk.MakePrivate(root); err != nil {
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return nil, err
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}
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// Populate the dir structure
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for _, p := range paths {
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if err := idtools.MkdirAllAs(path.Join(root, p), 0700, rootUID, rootGID); err != nil {
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return nil, err
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}
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}
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return a, nil
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}
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// Return a nil error if the kernel supports aufs
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// We cannot modprobe because inside dind modprobe fails
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// to run
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func supportsAufs() error {
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// We can try to modprobe aufs first before looking at
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// proc/filesystems for when aufs is supported
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exec.Command("modprobe", "aufs").Run()
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f, err := os.Open("/proc/filesystems")
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if err != nil {
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return err
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}
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defer f.Close()
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s := bufio.NewScanner(f)
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for s.Scan() {
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if strings.Contains(s.Text(), "aufs") {
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return nil
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}
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}
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return ErrAufsNotSupported
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}
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func (a *Driver) rootPath() string {
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return a.root
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}
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func (*Driver) String() string {
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return "aufs"
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}
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// Status returns current information about the filesystem such as root directory, number of directories mounted, etc.
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func (a *Driver) Status() [][2]string {
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ids, _ := loadIds(path.Join(a.rootPath(), "layers"))
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return [][2]string{
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{"Root Dir", a.rootPath()},
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{"Backing Filesystem", backingFs},
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{"Dirs", fmt.Sprintf("%d", len(ids))},
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{"Dirperm1 Supported", fmt.Sprintf("%v", useDirperm())},
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}
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}
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// GetMetadata not implemented
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func (a *Driver) GetMetadata(id string) (map[string]string, error) {
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return nil, nil
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}
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// Exists returns true if the given id is registered with
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// this driver
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func (a *Driver) Exists(id string) bool {
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if _, err := os.Lstat(path.Join(a.rootPath(), "layers", id)); err != nil {
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return false
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}
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return true
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}
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// Create three folders for each id
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// mnt, layers, and diff
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func (a *Driver) Create(id, parent, mountLabel string) error {
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if err := a.createDirsFor(id); err != nil {
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return err
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}
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// Write the layers metadata
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f, err := os.Create(path.Join(a.rootPath(), "layers", id))
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if err != nil {
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return err
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}
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defer f.Close()
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if parent != "" {
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ids, err := getParentIds(a.rootPath(), parent)
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if err != nil {
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return err
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}
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if _, err := fmt.Fprintln(f, parent); err != nil {
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return err
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}
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for _, i := range ids {
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if _, err := fmt.Fprintln(f, i); err != nil {
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return err
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}
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}
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}
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a.active[id] = &data{}
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return nil
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}
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func (a *Driver) createDirsFor(id string) error {
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paths := []string{
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"mnt",
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"diff",
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}
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rootUID, rootGID, err := idtools.GetRootUIDGID(a.uidMaps, a.gidMaps)
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if err != nil {
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return err
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}
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for _, p := range paths {
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if err := idtools.MkdirAllAs(path.Join(a.rootPath(), p, id), 0755, rootUID, rootGID); err != nil {
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return err
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}
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}
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return nil
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}
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// Remove will unmount and remove the given id.
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func (a *Driver) Remove(id string) error {
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// Protect the a.active from concurrent access
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a.Lock()
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defer a.Unlock()
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m := a.active[id]
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if m != nil {
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if m.referenceCount > 0 {
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return nil
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}
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// Make sure the dir is umounted first
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if err := a.unmount(m); err != nil {
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return err
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}
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}
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tmpDirs := []string{
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"mnt",
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"diff",
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}
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// Atomically remove each directory in turn by first moving it out of the
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// way (so that docker doesn't find it anymore) before doing removal of
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// the whole tree.
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for _, p := range tmpDirs {
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realPath := path.Join(a.rootPath(), p, id)
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tmpPath := path.Join(a.rootPath(), p, fmt.Sprintf("%s-removing", id))
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if err := os.Rename(realPath, tmpPath); err != nil && !os.IsNotExist(err) {
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return err
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}
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defer os.RemoveAll(tmpPath)
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}
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// Remove the layers file for the id
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if err := os.Remove(path.Join(a.rootPath(), "layers", id)); err != nil && !os.IsNotExist(err) {
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return err
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}
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return nil
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}
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// Get returns the rootfs path for the id.
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// This will mount the dir at it's given path
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func (a *Driver) Get(id, mountLabel string) (string, error) {
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ids, err := getParentIds(a.rootPath(), id)
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if err != nil {
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if !os.IsNotExist(err) {
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return "", err
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}
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ids = []string{}
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}
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// Protect the a.active from concurrent access
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a.Lock()
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defer a.Unlock()
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m := a.active[id]
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if m == nil {
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m = &data{}
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a.active[id] = m
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}
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// If a dir does not have a parent ( no layers )do not try to mount
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// just return the diff path to the data
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m.path = path.Join(a.rootPath(), "diff", id)
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if len(ids) > 0 {
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m.path = path.Join(a.rootPath(), "mnt", id)
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if m.referenceCount == 0 {
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if err := a.mount(id, m, mountLabel); err != nil {
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return "", err
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}
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}
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}
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m.referenceCount++
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return m.path, nil
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}
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// Put unmounts and updates list of active mounts.
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func (a *Driver) Put(id string) error {
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// Protect the a.active from concurrent access
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a.Lock()
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defer a.Unlock()
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m := a.active[id]
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if m == nil {
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// but it might be still here
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if a.Exists(id) {
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path := path.Join(a.rootPath(), "mnt", id)
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err := Unmount(path)
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if err != nil {
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logrus.Debugf("Failed to unmount %s aufs: %v", id, err)
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}
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}
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return nil
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}
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if count := m.referenceCount; count > 1 {
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m.referenceCount = count - 1
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} else {
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ids, _ := getParentIds(a.rootPath(), id)
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// We only mounted if there are any parents
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if ids != nil && len(ids) > 0 {
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a.unmount(m)
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}
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delete(a.active, id)
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}
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return nil
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}
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// Diff produces an archive of the changes between the specified
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// layer and its parent layer which may be "".
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func (a *Driver) Diff(id, parent string) (archive.Archive, error) {
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// AUFS doesn't need the parent layer to produce a diff.
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return archive.TarWithOptions(path.Join(a.rootPath(), "diff", id), &archive.TarOptions{
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Compression: archive.Uncompressed,
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ExcludePatterns: []string{archive.WhiteoutMetaPrefix + "*", "!" + archive.WhiteoutOpaqueDir},
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UIDMaps: a.uidMaps,
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GIDMaps: a.gidMaps,
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})
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}
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// DiffPath returns path to the directory that contains files for the layer
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// differences. Used for direct access for tar-split.
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func (a *Driver) DiffPath(id string) (string, func() error, error) {
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return path.Join(a.rootPath(), "diff", id), func() error { return nil }, nil
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}
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func (a *Driver) applyDiff(id string, diff archive.Reader) error {
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return chrootarchive.UntarUncompressed(diff, path.Join(a.rootPath(), "diff", id), &archive.TarOptions{
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UIDMaps: a.uidMaps,
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GIDMaps: a.gidMaps,
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})
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}
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// DiffSize calculates the changes between the specified id
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// and its parent and returns the size in bytes of the changes
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// relative to its base filesystem directory.
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func (a *Driver) DiffSize(id, parent string) (size int64, err error) {
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// AUFS doesn't need the parent layer to calculate the diff size.
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return directory.Size(path.Join(a.rootPath(), "diff", id))
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}
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// ApplyDiff extracts the changeset from the given diff into the
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// layer with the specified id and parent, returning the size of the
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// new layer in bytes.
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func (a *Driver) ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error) {
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// AUFS doesn't need the parent id to apply the diff.
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if err = a.applyDiff(id, diff); err != nil {
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return
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}
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return a.DiffSize(id, parent)
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}
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// Changes produces a list of changes between the specified layer
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// and its parent layer. If parent is "", then all changes will be ADD changes.
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func (a *Driver) Changes(id, parent string) ([]archive.Change, error) {
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// AUFS doesn't have snapshots, so we need to get changes from all parent
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// layers.
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layers, err := a.getParentLayerPaths(id)
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if err != nil {
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return nil, err
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}
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return archive.Changes(layers, path.Join(a.rootPath(), "diff", id))
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}
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func (a *Driver) getParentLayerPaths(id string) ([]string, error) {
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parentIds, err := getParentIds(a.rootPath(), id)
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if err != nil {
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return nil, err
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}
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layers := make([]string, len(parentIds))
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// Get the diff paths for all the parent ids
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for i, p := range parentIds {
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layers[i] = path.Join(a.rootPath(), "diff", p)
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}
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return layers, nil
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}
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func (a *Driver) mount(id string, m *data, mountLabel string) error {
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// If the id is mounted or we get an error return
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if mounted, err := a.mounted(m); err != nil || mounted {
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return err
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}
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var (
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target = m.path
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rw = path.Join(a.rootPath(), "diff", id)
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)
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layers, err := a.getParentLayerPaths(id)
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if err != nil {
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return err
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}
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if err := a.aufsMount(layers, rw, target, mountLabel); err != nil {
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return fmt.Errorf("error creating aufs mount to %s: %v", target, err)
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}
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return nil
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}
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func (a *Driver) unmount(m *data) error {
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if mounted, err := a.mounted(m); err != nil || !mounted {
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return err
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}
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return Unmount(m.path)
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}
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func (a *Driver) mounted(m *data) (bool, error) {
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return mountpk.Mounted(m.path)
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}
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// Cleanup aufs and unmount all mountpoints
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func (a *Driver) Cleanup() error {
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for id, m := range a.active {
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if err := a.unmount(m); err != nil {
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logrus.Errorf("Unmounting %s: %s", stringid.TruncateID(id), err)
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}
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}
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return mountpk.Unmount(a.root)
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}
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func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err error) {
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defer func() {
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if err != nil {
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Unmount(target)
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}
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}()
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// Mount options are clipped to page size(4096 bytes). If there are more
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// layers then these are remounted individually using append.
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offset := 54
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if useDirperm() {
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offset += len("dirperm1")
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}
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b := make([]byte, syscall.Getpagesize()-len(mountLabel)-offset) // room for xino & mountLabel
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bp := copy(b, fmt.Sprintf("br:%s=rw", rw))
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firstMount := true
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i := 0
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for {
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for ; i < len(ro); i++ {
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layer := fmt.Sprintf(":%s=ro+wh", ro[i])
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if firstMount {
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if bp+len(layer) > len(b) {
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break
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}
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bp += copy(b[bp:], layer)
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} else {
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data := label.FormatMountLabel(fmt.Sprintf("append%s", layer), mountLabel)
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if err = mount("none", target, "aufs", syscall.MS_REMOUNT, data); err != nil {
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return
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}
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}
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}
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if firstMount {
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opts := "dio,xino=/dev/shm/aufs.xino"
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if useDirperm() {
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opts += ",dirperm1"
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}
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data := label.FormatMountLabel(fmt.Sprintf("%s,%s", string(b[:bp]), opts), mountLabel)
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if err = mount("none", target, "aufs", 0, data); err != nil {
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return
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}
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firstMount = false
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}
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if i == len(ro) {
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break
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}
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}
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return
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}
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// useDirperm checks dirperm1 mount option can be used with the current
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// version of aufs.
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func useDirperm() bool {
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enableDirpermLock.Do(func() {
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base, err := ioutil.TempDir("", "docker-aufs-base")
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if err != nil {
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logrus.Errorf("error checking dirperm1: %v", err)
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return
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}
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defer os.RemoveAll(base)
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union, err := ioutil.TempDir("", "docker-aufs-union")
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if err != nil {
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logrus.Errorf("error checking dirperm1: %v", err)
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return
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}
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defer os.RemoveAll(union)
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opts := fmt.Sprintf("br:%s,dirperm1,xino=/dev/shm/aufs.xino", base)
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if err := mount("none", union, "aufs", 0, opts); err != nil {
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return
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}
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enableDirperm = true
|
|
if err := Unmount(union); err != nil {
|
|
logrus.Errorf("error checking dirperm1: failed to unmount %v", err)
|
|
}
|
|
})
|
|
return enableDirperm
|
|
}
|