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760 lines
23 KiB
Go
760 lines
23 KiB
Go
// +build linux
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package overlay2 // import "github.com/docker/docker/daemon/graphdriver/overlay2"
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import (
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"bufio"
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"errors"
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"fmt"
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"io"
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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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"path/filepath"
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"strconv"
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"strings"
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"sync"
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"github.com/docker/docker/daemon/graphdriver"
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"github.com/docker/docker/daemon/graphdriver/overlayutils"
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"github.com/docker/docker/daemon/graphdriver/quota"
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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/containerfs"
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"github.com/docker/docker/pkg/directory"
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"github.com/docker/docker/pkg/fsutils"
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"github.com/docker/docker/pkg/idtools"
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"github.com/docker/docker/pkg/locker"
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"github.com/docker/docker/pkg/mount"
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"github.com/docker/docker/pkg/parsers"
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"github.com/docker/docker/pkg/parsers/kernel"
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"github.com/docker/docker/pkg/system"
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"github.com/docker/go-units"
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rsystem "github.com/opencontainers/runc/libcontainer/system"
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"github.com/opencontainers/selinux/go-selinux/label"
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"github.com/sirupsen/logrus"
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"golang.org/x/sys/unix"
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)
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var (
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// untar defines the untar method
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untar = chrootarchive.UntarUncompressed
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)
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// This backend uses the overlay union filesystem for containers
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// with diff directories for each layer.
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// This version of the overlay driver requires at least kernel
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// 4.0.0 in order to support mounting multiple diff directories.
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// Each container/image has at least a "diff" directory and "link" file.
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// If there is also a "lower" file when there are diff layers
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// below as well as "merged" and "work" directories. The "diff" directory
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// has the upper layer of the overlay and is used to capture any
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// changes to the layer. The "lower" file contains all the lower layer
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// mounts separated by ":" and ordered from uppermost to lowermost
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// layers. The overlay itself is mounted in the "merged" directory,
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// and the "work" dir is needed for overlay to work.
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// The "link" file for each layer contains a unique string for the layer.
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// Under the "l" directory at the root there will be a symbolic link
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// with that unique string pointing the "diff" directory for the layer.
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// The symbolic links are used to reference lower layers in the "lower"
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// file and on mount. The links are used to shorten the total length
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// of a layer reference without requiring changes to the layer identifier
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// or root directory. Mounts are always done relative to root and
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// referencing the symbolic links in order to ensure the number of
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// lower directories can fit in a single page for making the mount
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// syscall. A hard upper limit of 128 lower layers is enforced to ensure
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// that mounts do not fail due to length.
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const (
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driverName = "overlay2"
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linkDir = "l"
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lowerFile = "lower"
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maxDepth = 128
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// idLength represents the number of random characters
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// which can be used to create the unique link identifier
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// for every layer. If this value is too long then the
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// page size limit for the mount command may be exceeded.
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// The idLength should be selected such that following equation
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// is true (512 is a buffer for label metadata).
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// ((idLength + len(linkDir) + 1) * maxDepth) <= (pageSize - 512)
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idLength = 26
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)
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type overlayOptions struct {
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overrideKernelCheck bool
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quota quota.Quota
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}
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// Driver contains information about the home directory and the list of active
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// mounts that are created using this driver.
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type Driver struct {
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home string
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uidMaps []idtools.IDMap
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gidMaps []idtools.IDMap
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ctr *graphdriver.RefCounter
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quotaCtl *quota.Control
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options overlayOptions
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naiveDiff graphdriver.DiffDriver
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supportsDType bool
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locker *locker.Locker
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}
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var (
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backingFs = "<unknown>"
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projectQuotaSupported = false
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useNaiveDiffLock sync.Once
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useNaiveDiffOnly bool
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)
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func init() {
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graphdriver.Register(driverName, Init)
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}
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// Init returns the native diff driver for overlay filesystem.
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// If overlay filesystem is not supported on the host, the error
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// graphdriver.ErrNotSupported is returned.
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// If an overlay filesystem is not supported over an existing filesystem then
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// the error graphdriver.ErrIncompatibleFS is returned.
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func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
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opts, err := parseOptions(options)
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if err != nil {
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return nil, err
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}
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if err := supportsOverlay(); err != nil {
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return nil, graphdriver.ErrNotSupported
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}
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// require kernel 4.0.0 to ensure multiple lower dirs are supported
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v, err := kernel.GetKernelVersion()
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if err != nil {
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return nil, err
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}
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// Perform feature detection on /var/lib/docker/overlay2 if it's an existing directory.
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// This covers situations where /var/lib/docker/overlay2 is a mount, and on a different
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// filesystem than /var/lib/docker.
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// If the path does not exist, fall back to using /var/lib/docker for feature detection.
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testdir := home
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if _, err := os.Stat(testdir); os.IsNotExist(err) {
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testdir = filepath.Dir(testdir)
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}
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fsMagic, err := graphdriver.GetFSMagic(testdir)
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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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switch fsMagic {
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case graphdriver.FsMagicAufs, graphdriver.FsMagicEcryptfs, graphdriver.FsMagicNfsFs, graphdriver.FsMagicOverlay, graphdriver.FsMagicZfs:
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logrus.Errorf("'overlay2' is not supported over %s", backingFs)
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return nil, graphdriver.ErrIncompatibleFS
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case graphdriver.FsMagicBtrfs:
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// Support for OverlayFS on BTRFS was added in kernel 4.7
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// See https://btrfs.wiki.kernel.org/index.php/Changelog
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if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 7, Minor: 0}) < 0 {
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if !opts.overrideKernelCheck {
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logrus.Errorf("'overlay2' requires kernel 4.7 to use on %s", backingFs)
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return nil, graphdriver.ErrIncompatibleFS
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}
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logrus.Warn("Using pre-4.7.0 kernel for overlay2 on btrfs, may require kernel update")
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}
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}
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if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 0, Minor: 0}) < 0 {
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if opts.overrideKernelCheck {
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logrus.Warn("Using pre-4.0.0 kernel for overlay2, mount failures may require kernel update")
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} else {
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if err := supportsMultipleLowerDir(testdir); err != nil {
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logrus.Debugf("Multiple lower dirs not supported: %v", err)
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return nil, graphdriver.ErrNotSupported
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}
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}
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}
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supportsDType, err := fsutils.SupportsDType(testdir)
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if err != nil {
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return nil, err
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}
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if !supportsDType {
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if !graphdriver.IsInitialized(home) {
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return nil, overlayutils.ErrDTypeNotSupported("overlay2", backingFs)
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}
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// allow running without d_type only for existing setups (#27443)
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logrus.Warn(overlayutils.ErrDTypeNotSupported("overlay2", backingFs))
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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 driver home dir
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if err := idtools.MkdirAllAndChown(path.Join(home, linkDir), 0700, idtools.IDPair{rootUID, rootGID}); err != nil {
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return nil, err
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}
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d := &Driver{
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home: home,
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uidMaps: uidMaps,
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gidMaps: gidMaps,
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ctr: graphdriver.NewRefCounter(graphdriver.NewFsChecker(graphdriver.FsMagicOverlay)),
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supportsDType: supportsDType,
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locker: locker.New(),
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options: *opts,
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}
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d.naiveDiff = graphdriver.NewNaiveDiffDriver(d, uidMaps, gidMaps)
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if backingFs == "xfs" {
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// Try to enable project quota support over xfs.
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if d.quotaCtl, err = quota.NewControl(home); err == nil {
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projectQuotaSupported = true
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} else if opts.quota.Size > 0 {
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return nil, fmt.Errorf("Storage option overlay2.size not supported. Filesystem does not support Project Quota: %v", err)
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}
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} else if opts.quota.Size > 0 {
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// if xfs is not the backing fs then error out if the storage-opt overlay2.size is used.
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return nil, fmt.Errorf("Storage Option overlay2.size only supported for backingFS XFS. Found %v", backingFs)
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}
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logrus.Debugf("backingFs=%s, projectQuotaSupported=%v", backingFs, projectQuotaSupported)
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return d, nil
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}
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func parseOptions(options []string) (*overlayOptions, error) {
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o := &overlayOptions{}
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for _, option := range options {
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key, val, err := parsers.ParseKeyValueOpt(option)
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if err != nil {
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return nil, err
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}
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key = strings.ToLower(key)
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switch key {
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case "overlay2.override_kernel_check":
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o.overrideKernelCheck, err = strconv.ParseBool(val)
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if err != nil {
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return nil, err
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}
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case "overlay2.size":
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size, err := units.RAMInBytes(val)
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if err != nil {
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return nil, err
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}
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o.quota.Size = uint64(size)
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default:
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return nil, fmt.Errorf("overlay2: unknown option %s", key)
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}
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}
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return o, nil
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}
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func supportsOverlay() error {
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// We can try to modprobe overlay first before looking at
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// proc/filesystems for when overlay is supported
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exec.Command("modprobe", "overlay").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 s.Text() == "nodev\toverlay" {
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return nil
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}
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}
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logrus.Error("'overlay' not found as a supported filesystem on this host. Please ensure kernel is new enough and has overlay support loaded.")
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return graphdriver.ErrNotSupported
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}
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func useNaiveDiff(home string) bool {
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useNaiveDiffLock.Do(func() {
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if err := doesSupportNativeDiff(home); err != nil {
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logrus.Warnf("Not using native diff for overlay2, this may cause degraded performance for building images: %v", err)
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useNaiveDiffOnly = true
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}
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})
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return useNaiveDiffOnly
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}
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func (d *Driver) String() string {
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return driverName
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}
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// Status returns current driver information in a two dimensional string array.
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// Output contains "Backing Filesystem" used in this implementation.
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func (d *Driver) Status() [][2]string {
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return [][2]string{
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{"Backing Filesystem", backingFs},
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{"Supports d_type", strconv.FormatBool(d.supportsDType)},
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{"Native Overlay Diff", strconv.FormatBool(!useNaiveDiff(d.home))},
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}
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}
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// GetMetadata returns metadata about the overlay driver such as the LowerDir,
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// UpperDir, WorkDir, and MergeDir used to store data.
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func (d *Driver) GetMetadata(id string) (map[string]string, error) {
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dir := d.dir(id)
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if _, err := os.Stat(dir); err != nil {
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return nil, err
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}
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metadata := map[string]string{
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"WorkDir": path.Join(dir, "work"),
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"MergedDir": path.Join(dir, "merged"),
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"UpperDir": path.Join(dir, "diff"),
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}
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lowerDirs, err := d.getLowerDirs(id)
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if err != nil {
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return nil, err
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}
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if len(lowerDirs) > 0 {
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metadata["LowerDir"] = strings.Join(lowerDirs, ":")
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}
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return metadata, nil
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}
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// Cleanup any state created by overlay which should be cleaned when daemon
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// is being shutdown. For now, we just have to unmount the bind mounted
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// we had created.
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func (d *Driver) Cleanup() error {
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return mount.RecursiveUnmount(d.home)
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}
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// CreateReadWrite creates a layer that is writable for use as a container
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// file system.
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func (d *Driver) CreateReadWrite(id, parent string, opts *graphdriver.CreateOpts) error {
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if opts != nil && len(opts.StorageOpt) != 0 && !projectQuotaSupported {
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return fmt.Errorf("--storage-opt is supported only for overlay over xfs with 'pquota' mount option")
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}
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if opts == nil {
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opts = &graphdriver.CreateOpts{
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StorageOpt: map[string]string{},
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}
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}
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if _, ok := opts.StorageOpt["size"]; !ok {
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if opts.StorageOpt == nil {
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opts.StorageOpt = map[string]string{}
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}
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opts.StorageOpt["size"] = strconv.FormatUint(d.options.quota.Size, 10)
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}
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return d.create(id, parent, opts)
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}
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// Create is used to create the upper, lower, and merge directories required for overlay fs for a given id.
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// The parent filesystem is used to configure these directories for the overlay.
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func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr error) {
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if opts != nil && len(opts.StorageOpt) != 0 {
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if _, ok := opts.StorageOpt["size"]; ok {
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return fmt.Errorf("--storage-opt size is only supported for ReadWrite Layers")
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}
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}
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return d.create(id, parent, opts)
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}
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func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr error) {
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dir := d.dir(id)
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rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)
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if err != nil {
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return err
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}
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root := idtools.IDPair{UID: rootUID, GID: rootGID}
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if err := idtools.MkdirAllAndChown(path.Dir(dir), 0700, root); err != nil {
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return err
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}
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if err := idtools.MkdirAndChown(dir, 0700, root); err != nil {
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return err
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}
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defer func() {
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// Clean up on failure
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if retErr != nil {
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os.RemoveAll(dir)
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}
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}()
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if opts != nil && len(opts.StorageOpt) > 0 {
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driver := &Driver{}
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if err := d.parseStorageOpt(opts.StorageOpt, driver); err != nil {
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return err
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}
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if driver.options.quota.Size > 0 {
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// Set container disk quota limit
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if err := d.quotaCtl.SetQuota(dir, driver.options.quota); err != nil {
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return err
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}
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}
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}
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if err := idtools.MkdirAndChown(path.Join(dir, "diff"), 0755, root); err != nil {
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return err
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}
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lid := generateID(idLength)
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if err := os.Symlink(path.Join("..", id, "diff"), path.Join(d.home, linkDir, lid)); err != nil {
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return err
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}
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// Write link id to link file
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if err := ioutil.WriteFile(path.Join(dir, "link"), []byte(lid), 0644); err != nil {
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return err
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}
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// if no parent directory, done
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if parent == "" {
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return nil
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}
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if err := idtools.MkdirAndChown(path.Join(dir, "work"), 0700, root); err != nil {
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return err
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}
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lower, err := d.getLower(parent)
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if err != nil {
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return err
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}
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if lower != "" {
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if err := ioutil.WriteFile(path.Join(dir, lowerFile), []byte(lower), 0666); 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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// Parse overlay storage options
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func (d *Driver) parseStorageOpt(storageOpt map[string]string, driver *Driver) error {
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// Read size to set the disk project quota per container
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for key, val := range storageOpt {
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key := strings.ToLower(key)
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switch key {
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case "size":
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size, err := units.RAMInBytes(val)
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if err != nil {
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return err
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}
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driver.options.quota.Size = uint64(size)
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default:
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return fmt.Errorf("Unknown option %s", key)
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}
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}
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return nil
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}
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func (d *Driver) getLower(parent string) (string, error) {
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parentDir := d.dir(parent)
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// Ensure parent exists
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if _, err := os.Lstat(parentDir); err != nil {
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return "", err
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}
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// Read Parent link fileA
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parentLink, err := ioutil.ReadFile(path.Join(parentDir, "link"))
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if err != nil {
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return "", err
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}
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lowers := []string{path.Join(linkDir, string(parentLink))}
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parentLower, err := ioutil.ReadFile(path.Join(parentDir, lowerFile))
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if err == nil {
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parentLowers := strings.Split(string(parentLower), ":")
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lowers = append(lowers, parentLowers...)
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}
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if len(lowers) > maxDepth {
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return "", errors.New("max depth exceeded")
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}
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return strings.Join(lowers, ":"), nil
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}
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func (d *Driver) dir(id string) string {
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return path.Join(d.home, id)
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}
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func (d *Driver) getLowerDirs(id string) ([]string, error) {
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var lowersArray []string
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lowers, err := ioutil.ReadFile(path.Join(d.dir(id), lowerFile))
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if err == nil {
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for _, s := range strings.Split(string(lowers), ":") {
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lp, err := os.Readlink(path.Join(d.home, s))
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if err != nil {
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return nil, err
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}
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lowersArray = append(lowersArray, path.Clean(path.Join(d.home, linkDir, lp)))
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}
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} else if !os.IsNotExist(err) {
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return nil, err
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}
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return lowersArray, nil
|
|
}
|
|
|
|
// Remove cleans the directories that are created for this id.
|
|
func (d *Driver) Remove(id string) error {
|
|
d.locker.Lock(id)
|
|
defer d.locker.Unlock(id)
|
|
dir := d.dir(id)
|
|
lid, err := ioutil.ReadFile(path.Join(dir, "link"))
|
|
if err == nil {
|
|
if err := os.RemoveAll(path.Join(d.home, linkDir, string(lid))); err != nil {
|
|
logrus.Debugf("Failed to remove link: %v", err)
|
|
}
|
|
}
|
|
|
|
if err := system.EnsureRemoveAll(dir); err != nil && !os.IsNotExist(err) {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Get creates and mounts the required file system for the given id and returns the mount path.
|
|
func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, retErr error) {
|
|
d.locker.Lock(id)
|
|
defer d.locker.Unlock(id)
|
|
dir := d.dir(id)
|
|
if _, err := os.Stat(dir); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
diffDir := path.Join(dir, "diff")
|
|
lowers, err := ioutil.ReadFile(path.Join(dir, lowerFile))
|
|
if err != nil {
|
|
// If no lower, just return diff directory
|
|
if os.IsNotExist(err) {
|
|
return containerfs.NewLocalContainerFS(diffDir), nil
|
|
}
|
|
return nil, err
|
|
}
|
|
|
|
mergedDir := path.Join(dir, "merged")
|
|
if count := d.ctr.Increment(mergedDir); count > 1 {
|
|
return containerfs.NewLocalContainerFS(mergedDir), nil
|
|
}
|
|
defer func() {
|
|
if retErr != nil {
|
|
if c := d.ctr.Decrement(mergedDir); c <= 0 {
|
|
if mntErr := unix.Unmount(mergedDir, 0); mntErr != nil {
|
|
logrus.Errorf("error unmounting %v: %v", mergedDir, mntErr)
|
|
}
|
|
// Cleanup the created merged directory; see the comment in Put's rmdir
|
|
if rmErr := unix.Rmdir(mergedDir); rmErr != nil && !os.IsNotExist(rmErr) {
|
|
logrus.Debugf("Failed to remove %s: %v: %v", id, rmErr, err)
|
|
}
|
|
}
|
|
}
|
|
}()
|
|
|
|
workDir := path.Join(dir, "work")
|
|
splitLowers := strings.Split(string(lowers), ":")
|
|
absLowers := make([]string, len(splitLowers))
|
|
for i, s := range splitLowers {
|
|
absLowers[i] = path.Join(d.home, s)
|
|
}
|
|
opts := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", strings.Join(absLowers, ":"), path.Join(dir, "diff"), path.Join(dir, "work"))
|
|
mountData := label.FormatMountLabel(opts, mountLabel)
|
|
mount := unix.Mount
|
|
mountTarget := mergedDir
|
|
|
|
rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := idtools.MkdirAndChown(mergedDir, 0700, idtools.IDPair{rootUID, rootGID}); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
pageSize := unix.Getpagesize()
|
|
|
|
// Go can return a larger page size than supported by the system
|
|
// as of go 1.7. This will be fixed in 1.8 and this block can be
|
|
// removed when building with 1.8.
|
|
// See https://github.com/golang/go/commit/1b9499b06989d2831e5b156161d6c07642926ee1
|
|
// See https://github.com/docker/docker/issues/27384
|
|
if pageSize > 4096 {
|
|
pageSize = 4096
|
|
}
|
|
|
|
// Use relative paths and mountFrom when the mount data has exceeded
|
|
// the page size. The mount syscall fails if the mount data cannot
|
|
// fit within a page and relative links make the mount data much
|
|
// smaller at the expense of requiring a fork exec to chroot.
|
|
if len(mountData) > pageSize {
|
|
opts = fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", string(lowers), path.Join(id, "diff"), path.Join(id, "work"))
|
|
mountData = label.FormatMountLabel(opts, mountLabel)
|
|
if len(mountData) > pageSize {
|
|
return nil, fmt.Errorf("cannot mount layer, mount label too large %d", len(mountData))
|
|
}
|
|
|
|
mount = func(source string, target string, mType string, flags uintptr, label string) error {
|
|
return mountFrom(d.home, source, target, mType, flags, label)
|
|
}
|
|
mountTarget = path.Join(id, "merged")
|
|
}
|
|
|
|
if err := mount("overlay", mountTarget, "overlay", 0, mountData); err != nil {
|
|
return nil, fmt.Errorf("error creating overlay mount to %s: %v", mergedDir, err)
|
|
}
|
|
|
|
// chown "workdir/work" to the remapped root UID/GID. Overlay fs inside a
|
|
// user namespace requires this to move a directory from lower to upper.
|
|
if err := os.Chown(path.Join(workDir, "work"), rootUID, rootGID); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return containerfs.NewLocalContainerFS(mergedDir), nil
|
|
}
|
|
|
|
// Put unmounts the mount path created for the give id.
|
|
// It also removes the 'merged' directory to force the kernel to unmount the
|
|
// overlay mount in other namespaces.
|
|
func (d *Driver) Put(id string) error {
|
|
d.locker.Lock(id)
|
|
defer d.locker.Unlock(id)
|
|
dir := d.dir(id)
|
|
_, err := ioutil.ReadFile(path.Join(dir, lowerFile))
|
|
if err != nil {
|
|
// If no lower, no mount happened and just return directly
|
|
if os.IsNotExist(err) {
|
|
return nil
|
|
}
|
|
return err
|
|
}
|
|
|
|
mountpoint := path.Join(dir, "merged")
|
|
if count := d.ctr.Decrement(mountpoint); count > 0 {
|
|
return nil
|
|
}
|
|
if err := unix.Unmount(mountpoint, unix.MNT_DETACH); err != nil {
|
|
logrus.Debugf("Failed to unmount %s overlay: %s - %v", id, mountpoint, err)
|
|
}
|
|
// Remove the mountpoint here. Removing the mountpoint (in newer kernels)
|
|
// will cause all other instances of this mount in other mount namespaces
|
|
// to be unmounted. This is necessary to avoid cases where an overlay mount
|
|
// that is present in another namespace will cause subsequent mounts
|
|
// operations to fail with ebusy. We ignore any errors here because this may
|
|
// fail on older kernels which don't have
|
|
// torvalds/linux@8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe applied.
|
|
if err := unix.Rmdir(mountpoint); err != nil && !os.IsNotExist(err) {
|
|
logrus.Debugf("Failed to remove %s overlay: %v", id, err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Exists checks to see if the id is already mounted.
|
|
func (d *Driver) Exists(id string) bool {
|
|
_, err := os.Stat(d.dir(id))
|
|
return err == nil
|
|
}
|
|
|
|
// isParent determines whether the given parent is the direct parent of the
|
|
// given layer id
|
|
func (d *Driver) isParent(id, parent string) bool {
|
|
lowers, err := d.getLowerDirs(id)
|
|
if err != nil {
|
|
return false
|
|
}
|
|
if parent == "" && len(lowers) > 0 {
|
|
return false
|
|
}
|
|
|
|
parentDir := d.dir(parent)
|
|
var ld string
|
|
if len(lowers) > 0 {
|
|
ld = filepath.Dir(lowers[0])
|
|
}
|
|
if ld == "" && parent == "" {
|
|
return true
|
|
}
|
|
return ld == parentDir
|
|
}
|
|
|
|
// ApplyDiff applies the new layer into a root
|
|
func (d *Driver) ApplyDiff(id string, parent string, diff io.Reader) (size int64, err error) {
|
|
if !d.isParent(id, parent) {
|
|
return d.naiveDiff.ApplyDiff(id, parent, diff)
|
|
}
|
|
|
|
applyDir := d.getDiffPath(id)
|
|
|
|
logrus.Debugf("Applying tar in %s", applyDir)
|
|
// Overlay doesn't need the parent id to apply the diff
|
|
if err := untar(diff, applyDir, &archive.TarOptions{
|
|
UIDMaps: d.uidMaps,
|
|
GIDMaps: d.gidMaps,
|
|
WhiteoutFormat: archive.OverlayWhiteoutFormat,
|
|
InUserNS: rsystem.RunningInUserNS(),
|
|
}); err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
return directory.Size(applyDir)
|
|
}
|
|
|
|
func (d *Driver) getDiffPath(id string) string {
|
|
dir := d.dir(id)
|
|
|
|
return path.Join(dir, "diff")
|
|
}
|
|
|
|
// DiffSize calculates the changes between the specified id
|
|
// and its parent and returns the size in bytes of the changes
|
|
// relative to its base filesystem directory.
|
|
func (d *Driver) DiffSize(id, parent string) (size int64, err error) {
|
|
if useNaiveDiff(d.home) || !d.isParent(id, parent) {
|
|
return d.naiveDiff.DiffSize(id, parent)
|
|
}
|
|
return directory.Size(d.getDiffPath(id))
|
|
}
|
|
|
|
// Diff produces an archive of the changes between the specified
|
|
// layer and its parent layer which may be "".
|
|
func (d *Driver) Diff(id, parent string) (io.ReadCloser, error) {
|
|
if useNaiveDiff(d.home) || !d.isParent(id, parent) {
|
|
return d.naiveDiff.Diff(id, parent)
|
|
}
|
|
|
|
diffPath := d.getDiffPath(id)
|
|
logrus.Debugf("Tar with options on %s", diffPath)
|
|
return archive.TarWithOptions(diffPath, &archive.TarOptions{
|
|
Compression: archive.Uncompressed,
|
|
UIDMaps: d.uidMaps,
|
|
GIDMaps: d.gidMaps,
|
|
WhiteoutFormat: archive.OverlayWhiteoutFormat,
|
|
})
|
|
}
|
|
|
|
// Changes produces a list of changes between the specified layer and its
|
|
// parent layer. If parent is "", then all changes will be ADD changes.
|
|
func (d *Driver) Changes(id, parent string) ([]archive.Change, error) {
|
|
if useNaiveDiff(d.home) || !d.isParent(id, parent) {
|
|
return d.naiveDiff.Changes(id, parent)
|
|
}
|
|
// Overlay doesn't have snapshots, so we need to get changes from all parent
|
|
// layers.
|
|
diffPath := d.getDiffPath(id)
|
|
layers, err := d.getLowerDirs(id)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return archive.OverlayChanges(layers, diffPath)
|
|
}
|