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Merge pull request #34948 from euank/public-mounts

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Fix EBUSY errors under overlayfs and v4.13+ kernels
This commit is contained in:
Akihiro Suda 2017-11-29 12:48:39 +09:00 committed by GitHub
commit 09eb7bcc36
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 72 additions and 32 deletions
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48
daemon/graphdriver/overlay/overlay.go
View file

@ -109,8 +109,10 @@ func init() {
}
// Init returns the NaiveDiffDriver, a native diff driver for overlay filesystem.
// If overlay filesystem is not supported on the host, graphdriver.ErrNotSupported is returned as error.
// If an overlay filesystem is not supported over an existing filesystem then error graphdriver.ErrIncompatibleFS is returned.
// If overlay filesystem is not supported on the host, the error
// graphdriver.ErrNotSupported is returned.
// If an overlay filesystem is not supported over an existing filesystem then
// error graphdriver.ErrIncompatibleFS is returned.
func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
if err := supportsOverlay(); err != nil {
@ -199,7 +201,8 @@ func (d *Driver) Status() [][2]string {
}
}
// GetMetadata returns meta data about the overlay driver such as root, LowerDir, UpperDir, WorkDir and MergeDir used to store data.
// GetMetadata returns metadata about the overlay driver such as root,
// LowerDir, UpperDir, WorkDir and MergeDir used to store data.
func (d *Driver) GetMetadata(id string) (map[string]string, error) {
dir := d.dir(id)
if _, err := os.Stat(dir); err != nil {
@ -293,9 +296,6 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr
if err := idtools.MkdirAndChown(path.Join(dir, "work"), 0700, root); err != nil {
return err
}
if err := idtools.MkdirAndChown(path.Join(dir, "merged"), 0700, root); err != nil {
return err
}
if err := ioutil.WriteFile(path.Join(dir, "lower-id"), []byte(parent), 0666); err != nil {
return err
}
@ -326,9 +326,6 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr
if err := idtools.MkdirAndChown(path.Join(dir, "work"), 0700, root); err != nil {
return err
}
if err := idtools.MkdirAndChown(path.Join(dir, "merged"), 0700, root); err != nil {
return err
}
return copy.DirCopy(parentUpperDir, upperDir, copy.Content)
}
@ -357,6 +354,7 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, err erro
if _, err := os.Stat(rootDir); err == nil {
return containerfs.NewLocalContainerFS(rootDir), nil
}
mergedDir := path.Join(dir, "merged")
if count := d.ctr.Increment(mergedDir); count > 1 {
return containerfs.NewLocalContainerFS(mergedDir), nil
@ -364,7 +362,13 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, err erro
defer func() {
if err != nil {
if c := d.ctr.Decrement(mergedDir); c <= 0 {
unix.Unmount(mergedDir, 0)
if mntErr := unix.Unmount(mergedDir, 0); mntErr != nil {
logrus.Debugf("Failed to unmount %s: %v: %v", id, mntErr, err)
}
// Cleanup the created merged directory; see the comment in Put's rmdir
if rmErr := unix.Rmdir(mergedDir); rmErr != nil && !os.IsNotExist(rmErr) {
logrus.Warnf("Failed to remove %s: %v: %v", id, rmErr, err)
}
}
}
}()
@ -372,6 +376,13 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, err erro
if err != nil {
return nil, err
}
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
}
var (
lowerDir = path.Join(d.dir(string(lowerID)), "root")
upperDir = path.Join(dir, "upper")
@ -383,10 +394,6 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, err erro
}
// 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.
rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)
if err != nil {
return nil, err
}
if err := os.Chown(path.Join(workDir, "work"), rootUID, rootGID); err != nil {
return nil, err
}
@ -394,6 +401,8 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, err erro
}
// 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)
@ -408,6 +417,17 @@ func (d *Driver) Put(id string) error {
if err := unix.Unmount(mountpoint, unix.MNT_DETACH); err != nil {
logrus.Debugf("Failed to unmount %s overlay: %v", id, 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 {
logrus.Debugf("Failed to remove %s overlay: %v", id, err)
}
return nil
}

56
daemon/graphdriver/overlay2/overlay.go
View file

@ -77,7 +77,7 @@ const (
maxDepth = 128
// idLength represents the number of random characters
// which can be used to create the unique link identifer
// which can be used to create the unique link identifier
// for every layer. If this value is too long then the
// page size limit for the mount command may be exceeded.
// The idLength should be selected such that following equation
@ -91,7 +91,8 @@ type overlayOptions struct {
quota quota.Quota
}
// Driver contains information about the home directory and the list of active mounts that are created using this driver.
// Driver contains information about the home directory and the list of active
// mounts that are created using this driver.
type Driver struct {
home string
uidMaps []idtools.IDMap
@ -116,9 +117,11 @@ func init() {
graphdriver.Register(driverName, Init)
}
// Init returns the a native diff driver for overlay filesystem.
// If overlay filesystem is not supported on the host, graphdriver.ErrNotSupported is returned as error.
// If an overlay filesystem is not supported over an existing filesystem then error graphdriver.ErrIncompatibleFS is returned.
// Init returns the native diff driver for overlay filesystem.
// If overlay filesystem is not supported on the host, the error
// graphdriver.ErrNotSupported is returned.
// If an overlay filesystem is not supported over an existing filesystem then
// the error graphdriver.ErrIncompatibleFS is returned.
func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
opts, err := parseOptions(options)
if err != nil {
@ -289,8 +292,8 @@ func (d *Driver) Status() [][2]string {
}
}
// GetMetadata returns meta data about the overlay driver such as
// LowerDir, UpperDir, WorkDir and MergeDir used to store data.
// GetMetadata returns metadata about the overlay driver such as the LowerDir,
// UpperDir, WorkDir, and MergeDir used to store data.
func (d *Driver) GetMetadata(id string) (map[string]string, error) {
dir := d.dir(id)
if _, err := os.Stat(dir); err != nil {
@ -414,9 +417,6 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts) (retErr
if err := idtools.MkdirAndChown(path.Join(dir, "work"), 0700, root); err != nil {
return err
}
if err := idtools.MkdirAndChown(path.Join(dir, "merged"), 0700, root); err != nil {
return err
}
lower, err := d.getLower(parent)
if err != nil {
@ -545,6 +545,10 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, retErr e
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)
}
}
}
}()
@ -560,6 +564,14 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, retErr e
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
@ -594,11 +606,6 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, retErr e
// 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.
rootUID, rootGID, err := idtools.GetRootUIDGID(d.uidMaps, d.gidMaps)
if err != nil {
return nil, err
}
if err := os.Chown(path.Join(workDir, "work"), rootUID, rootGID); err != nil {
return nil, err
}
@ -607,6 +614,8 @@ func (d *Driver) Get(id, mountLabel string) (_ containerfs.ContainerFS, retErr e
}
// 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)
@ -627,6 +636,16 @@ func (d *Driver) Put(id string) error {
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
}
@ -636,7 +655,8 @@ func (d *Driver) Exists(id string) bool {
return err == nil
}
// isParent returns if the passed in parent is the direct parent of the passed in layer
// 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 {
@ -711,8 +731,8 @@ func (d *Driver) Diff(id, parent string) (io.ReadCloser, error) {
})
}
// Changes produces a list of changes between the specified layer
// and its parent layer. If parent is "", then all changes will be ADD changes.
// 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)