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Merge pull request #40462 from AkihiroSuda/cherrypick-40210-1903

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[19.03 backport] overlay[2]: rm extra checks in init
This commit is contained in:
Akihiro Suda 2020-02-18 18:04:05 +09:00 committed by GitHub
commit 4ac62b478d
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 58 additions and 139 deletions
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10
daemon/graphdriver/devmapper/deviceset.go
View file

@ -540,8 +540,14 @@ func xfsSupported() error {
return err // error text is descriptive enough
}
// Check if kernel supports xfs filesystem or not.
exec.Command("modprobe", "xfs").Run()
mountTarget, err := ioutil.TempDir("", "supportsXFS")
if err != nil {
return errors.Wrapf(err, "error checking for xfs support")
}
/* The mounting will fail--after the module has been loaded.*/
defer os.RemoveAll(mountTarget)
unix.Mount("none", mountTarget, "xfs", 0, "")
f, err := os.Open("/proc/filesystems")
if err != nil {

42
daemon/graphdriver/overlay/overlay.go
View file

@ -3,12 +3,10 @@
package overlay // import "github.com/docker/docker/daemon/graphdriver/overlay"
import (
"bufio"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path"
"path/filepath"
"strconv"
@ -124,10 +122,6 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
return nil, err
}
if err := supportsOverlay(); err != nil {
return nil, graphdriver.ErrNotSupported
}
// Perform feature detection on /var/lib/docker/overlay if it's an existing directory.
// This covers situations where /var/lib/docker/overlay is a mount, and on a different
// filesystem than /var/lib/docker.
@ -137,18 +131,9 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
testdir = filepath.Dir(testdir)
}
fsMagic, err := graphdriver.GetFSMagic(testdir)
if err != nil {
return nil, err
}
if fsName, ok := graphdriver.FsNames[fsMagic]; ok {
backingFs = fsName
}
switch fsMagic {
case graphdriver.FsMagicAufs, graphdriver.FsMagicBtrfs, graphdriver.FsMagicEcryptfs, graphdriver.FsMagicNfsFs, graphdriver.FsMagicOverlay, graphdriver.FsMagicZfs:
logrus.WithField("storage-driver", "overlay").Errorf("'overlay' is not supported over %s", backingFs)
return nil, graphdriver.ErrIncompatibleFS
if err := overlayutils.SupportsOverlay(testdir, false); err != nil {
logrus.WithField("storage-driver", "overlay").Error(err)
return nil, graphdriver.ErrNotSupported
}
supportsDType, err := fsutils.SupportsDType(testdir)
@ -200,27 +185,6 @@ func parseOptions(options []string) (*overlayOptions, error) {
return o, nil
}
func supportsOverlay() error {
// We can try to modprobe overlay first before looking at
// proc/filesystems for when overlay is supported
exec.Command("modprobe", "overlay").Run()
f, err := os.Open("/proc/filesystems")
if err != nil {
return err
}
defer f.Close()
s := bufio.NewScanner(f)
for s.Scan() {
if s.Text() == "nodev\toverlay" {
return nil
}
}
logrus.WithField("storage-driver", "overlay").Error("'overlay' not found as a supported filesystem on this host. Please ensure kernel is new enough and has overlay support loaded.")
return graphdriver.ErrNotSupported
}
func (d *Driver) String() string {
return "overlay"
}

32
daemon/graphdriver/overlay2/check.go
View file

@ -99,35 +99,3 @@ func doesSupportNativeDiff(d string) error {
return nil
}
// supportsMultipleLowerDir checks if the system supports multiple lowerdirs,
// which is required for the overlay2 driver. On 4.x kernels, multiple lowerdirs
// are always available (so this check isn't needed), and backported to RHEL and
// CentOS 3.x kernels (3.10.0-693.el7.x86_64 and up). This function is to detect
// support on those kernels, without doing a kernel version compare.
func supportsMultipleLowerDir(d string) error {
td, err := ioutil.TempDir(d, "multiple-lowerdir-check")
if err != nil {
return err
}
defer func() {
if err := os.RemoveAll(td); err != nil {
logger.Warnf("Failed to remove check directory %v: %v", td, err)
}
}()
for _, dir := range []string{"lower1", "lower2", "upper", workDirName, mergedDirName} {
if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil {
return err
}
}
opts := fmt.Sprintf("lowerdir=%s:%s,upperdir=%s,workdir=%s", path.Join(td, "lower2"), path.Join(td, "lower1"), path.Join(td, "upper"), path.Join(td, workDirName))
if err := unix.Mount("overlay", filepath.Join(td, mergedDirName), "overlay", 0, opts); err != nil {
return errors.Wrap(err, "failed to mount overlay")
}
if err := unix.Unmount(filepath.Join(td, mergedDirName), 0); err != nil {
logger.Warnf("Failed to unmount check directory %v: %v", filepath.Join(td, mergedDirName), err)
}
return nil
}

69
daemon/graphdriver/overlay2/overlay.go
View file

@ -3,14 +3,12 @@
package overlay2 // import "github.com/docker/docker/daemon/graphdriver/overlay2"
import (
"bufio"
"context"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path"
"path/filepath"
"strconv"
@ -29,7 +27,6 @@ import (
"github.com/docker/docker/pkg/locker"
"github.com/docker/docker/pkg/mount"
"github.com/docker/docker/pkg/parsers"
"github.com/docker/docker/pkg/parsers/kernel"
"github.com/docker/docker/pkg/system"
"github.com/docker/go-units"
rsystem "github.com/opencontainers/runc/libcontainer/system"
@ -134,16 +131,6 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
return nil, err
}
if err := supportsOverlay(); err != nil {
return nil, graphdriver.ErrNotSupported
}
// require kernel 4.0.0 to ensure multiple lower dirs are supported
v, err := kernel.GetKernelVersion()
if err != nil {
return nil, err
}
// Perform feature detection on /var/lib/docker/overlay2 if it's an existing directory.
// This covers situations where /var/lib/docker/overlay2 is a mount, and on a different
// filesystem than /var/lib/docker.
@ -153,40 +140,11 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
testdir = filepath.Dir(testdir)
}
fsMagic, err := graphdriver.GetFSMagic(testdir)
if err != nil {
return nil, err
}
if fsName, ok := graphdriver.FsNames[fsMagic]; ok {
backingFs = fsName
if err := overlayutils.SupportsOverlay(testdir, true); err != nil {
logger.Error(err)
return nil, graphdriver.ErrNotSupported
}
switch fsMagic {
case graphdriver.FsMagicAufs, graphdriver.FsMagicEcryptfs, graphdriver.FsMagicNfsFs, graphdriver.FsMagicOverlay, graphdriver.FsMagicZfs:
logger.Errorf("'overlay2' is not supported over %s", backingFs)
return nil, graphdriver.ErrIncompatibleFS
case graphdriver.FsMagicBtrfs:
// Support for OverlayFS on BTRFS was added in kernel 4.7
// See https://btrfs.wiki.kernel.org/index.php/Changelog
if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 7, Minor: 0}) < 0 {
if !opts.overrideKernelCheck {
logger.Errorf("'overlay2' requires kernel 4.7 to use on %s", backingFs)
return nil, graphdriver.ErrIncompatibleFS
}
logger.Warn("Using pre-4.7.0 kernel for overlay2 on btrfs, may require kernel update")
}
}
if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 0, Minor: 0}) < 0 {
if opts.overrideKernelCheck {
logger.Warn("Using pre-4.0.0 kernel for overlay2, mount failures may require kernel update")
} else {
if err := supportsMultipleLowerDir(testdir); err != nil {
logger.Debugf("Multiple lower dirs not supported: %v", err)
return nil, graphdriver.ErrNotSupported
}
}
}
supportsDType, err := fsutils.SupportsDType(testdir)
if err != nil {
return nil, err
@ -275,27 +233,6 @@ func parseOptions(options []string) (*overlayOptions, error) {
return o, nil
}
func supportsOverlay() error {
// We can try to modprobe overlay first before looking at
// proc/filesystems for when overlay is supported
exec.Command("modprobe", "overlay").Run()
f, err := os.Open("/proc/filesystems")
if err != nil {
return err
}
defer f.Close()
s := bufio.NewScanner(f)
for s.Scan() {
if s.Text() == "nodev\toverlay" {
return nil
}
}
logger.Error("'overlay' not found as a supported filesystem on this host. Please ensure kernel is new enough and has overlay support loaded.")
return graphdriver.ErrNotSupported
}
func useNaiveDiff(home string) bool {
useNaiveDiffLock.Do(func() {
if err := doesSupportNativeDiff(home); err != nil {

44
daemon/graphdriver/overlayutils/overlayutils.go
View file

@ -4,8 +4,15 @@ package overlayutils // import "github.com/docker/docker/daemon/graphdriver/over
import (
"fmt"
"io/ioutil"
"os"
"path"
"path/filepath"
"github.com/docker/docker/daemon/graphdriver"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
// ErrDTypeNotSupported denotes that the backing filesystem doesn't support d_type.
@ -23,3 +30,40 @@ func ErrDTypeNotSupported(driver, backingFs string) error {
return graphdriver.NotSupportedError(msg)
}
// SupportsOverlay checks if the system supports overlay filesystem
// by performing an actual overlay mount.
//
// checkMultipleLowers parameter enables check for multiple lowerdirs,
// which is required for the overlay2 driver.
func SupportsOverlay(d string, checkMultipleLowers bool) error {
td, err := ioutil.TempDir(d, "check-overlayfs-support")
if err != nil {
return err
}
defer func() {
if err := os.RemoveAll(td); err != nil {
logrus.Warnf("Failed to remove check directory %v: %v", td, err)
}
}()
for _, dir := range []string{"lower1", "lower2", "upper", "work", "merged"} {
if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil {
return err
}
}
mnt := filepath.Join(td, "merged")
lowerDir := path.Join(td, "lower2")
if checkMultipleLowers {
lowerDir += ":" + path.Join(td, "lower1")
}
opts := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDir, path.Join(td, "upper"), path.Join(td, "work"))
if err := unix.Mount("overlay", mnt, "overlay", 0, opts); err != nil {
return errors.Wrap(err, "failed to mount overlay")
}
if err := unix.Unmount(mnt, 0); err != nil {
logrus.Warnf("Failed to unmount check directory %v: %v", mnt, err)
}
return nil
}