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os.Unmount: do not consult mountinfo, drop flags

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1. Currently, Unmount() call takes a burden to parse the whole nine yards
of /proc/self/mountinfo to figure out whether the given mount point is
mounted or not (and returns an error in case parsing fails somehow).

Instead, let's just call umount() and ignore EINVAL, which results
in the same behavior, but much better performance.

This also introduces a slight change: in case target does not exist,
the appropriate error (ENOENT) is returned -- document that.

2. As Unmount() is always used with MNT_DETACH flag, let's drop the
flags argument. This way, the only reason of EINVAL returned from
umount(2) can only be "target is not mounted".

3. While at it, remove the 'containerdmount' alias from the package.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2018-04-26 13:06:34 -07:00
parent 8fec0469d9
commit daeab40b45
4 changed files with 23 additions and 24 deletions
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30
pkg/os/os.go
View File

@ -22,9 +22,8 @@ import (
"os"
"path/filepath"
containerdmount "github.com/containerd/containerd/mount"
"github.com/containerd/containerd/mount"
"github.com/containerd/fifo"
"github.com/docker/docker/pkg/mount"
"github.com/docker/docker/pkg/symlink"
"golang.org/x/net/context"
"golang.org/x/sys/unix"
@ -42,8 +41,8 @@ type OS interface {
CopyFile(src, dest string, perm os.FileMode) error
WriteFile(filename string, data []byte, perm os.FileMode) error
Mount(source string, target string, fstype string, flags uintptr, data string) error
Unmount(target string, flags int) error
LookupMount(path string) (containerdmount.Info, error)
Unmount(target string) error
LookupMount(path string) (mount.Info, error)
}
// RealOS is used to dispatch the real system level operations.
@ -115,20 +114,23 @@ func (RealOS) Mount(source string, target string, fstype string, flags uintptr,
}
// Unmount will call Unmount to unmount the file.
func (RealOS) Unmount(target string, flags int) error {
return Unmount(target, flags)
func (RealOS) Unmount(target string) error {
return Unmount(target)
}
// LookupMount gets mount info of a given path.
func (RealOS) LookupMount(path string) (containerdmount.Info, error) {
return containerdmount.Lookup(path)
func (RealOS) LookupMount(path string) (mount.Info, error) {
return mount.Lookup(path)
}
// Unmount unmounts the target. It does not return an error in case the target is not mounted.
// In case the target does not exist, the appropriate error is returned.
func Unmount(target string) error {
err := unix.Unmount(target, unix.MNT_DETACH)
if err == unix.EINVAL {
// ignore "not mounted" error
err = nil
}
// Unmount will call unix.Unmount to unmount the file. The function doesn't
// return error if target is not mounted.
func Unmount(target string, flags int) error {
if mounted, err := mount.Mounted(target); err != nil || !mounted {
return err
}
return unix.Unmount(target, flags)
}

8
pkg/os/testing/fake_os.go
View File

@ -49,7 +49,7 @@ type FakeOS struct {
CopyFileFn func(string, string, os.FileMode) error
WriteFileFn func(string, []byte, os.FileMode) error
MountFn func(source string, target string, fstype string, flags uintptr, data string) error
UnmountFn func(target string, flags int) error
UnmountFn func(target string) error
LookupMountFn func(path string) (containerdmount.Info, error)
calls []CalledDetail
errors map[string]error
@ -230,14 +230,14 @@ func (f *FakeOS) Mount(source string, target string, fstype string, flags uintpt
}
// Unmount is a fake call that invokes UnmountFn or just return nil.
func (f *FakeOS) Unmount(target string, flags int) error {
f.appendCalls("Unmount", target, flags)
func (f *FakeOS) Unmount(target string) error {
f.appendCalls("Unmount", target)
if err := f.getError("Unmount"); err != nil {
return err
}
if f.UnmountFn != nil {
return f.UnmountFn(target, flags)
return f.UnmountFn(target)
}
return nil
}

6
pkg/server/sandbox_run.go
View File

@ -494,16 +494,14 @@ func parseDNSOptions(servers, searches, options []string) (string, error) {
}
// unmountSandboxFiles unmount some sandbox files, we rely on the removal of sandbox root directory to
// remove these files. Unmount should *NOT* return error when:
// 1) The mount point is already unmounted.
// 2) The mount point doesn't exist.
// remove these files. Unmount should *NOT* return error if the mount point is already unmounted.
func (c *criService) unmountSandboxFiles(id string, config *runtime.PodSandboxConfig) error {
if config.GetLinux().GetSecurityContext().GetNamespaceOptions().GetIpc() != runtime.NamespaceMode_NODE {
path, err := c.os.FollowSymlinkInScope(c.getSandboxDevShm(id), "/")
if err != nil {
return errors.Wrap(err, "failed to follow symlink")
}
if err := c.os.Unmount(path, unix.MNT_DETACH); err != nil && !os.IsNotExist(err) {
if err := c.os.Unmount(path); err != nil && !os.IsNotExist(err) {
return errors.Wrapf(err, "failed to unmount %q", path)
}
}

3
pkg/store/sandbox/netns.go
View File

@ -23,7 +23,6 @@ import (
cnins "github.com/containernetworking/plugins/pkg/ns"
"github.com/docker/docker/pkg/symlink"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
osinterface "github.com/containerd/cri/pkg/os"
)
@ -93,7 +92,7 @@ func (n *NetNS) Remove() error {
if err != nil {
return errors.Wrap(err, "failed to follow symlink")
}
if err := osinterface.Unmount(path, unix.MNT_DETACH); err != nil && !os.IsNotExist(err) {
if err := osinterface.Unmount(path); err != nil && !os.IsNotExist(err) {
return errors.Wrap(err, "failed to umount netns")
}
if err := os.RemoveAll(path); err != nil {