@@ -74,7 +74,7 @@ func (daemon *Daemon) cleanupMounts() error {

 		return err

 	}

-	infos, err := mount.GetMounts()

+	infos, err := mount.GetMounts(nil)

 	if err != nil {

 		return errors.Wrap(err, "error reading mount table for cleanup")

 	}

@@ -145,7 +145,7 @@ func lookupZfsDataset(rootdir string) (string, error) {

 	}

 	wantedDev := stat.Dev

-	mounts, err := mount.GetMounts()

+	mounts, err := mount.GetMounts(nil)

 	if err != nil {

 		return "", err

 	}

@@ -398,7 +398,7 @@ func getSourceMount(source string) (string, string, error) {

 		return "", "", err

 	}

-	mountinfos, err := mount.GetMounts()

+	mountinfos, err := mount.GetMounts(nil)

 	if err != nil {

 		return "", "", err

 	}

@@ -260,7 +260,7 @@ func (s *DockerDaemonSuite) TestPluginVolumeRemoveOnRestart(c *check.C) {

 }

 func existsMountpointWithPrefix(mountpointPrefix string) (bool, error) {

-	mounts, err := mount.GetMounts()

+	mounts, err := mount.GetMounts(nil)

 	if err != nil {

 		return false, err

 	}

@@ -9,26 +9,48 @@ import (

 	"github.com/sirupsen/logrus"

 )

-// GetMounts retrieves a list of mounts for the current running process.

-func GetMounts() ([]*Info, error) {

-	return parseMountTable()

+// FilterFunc is a type defining a callback function

+// to filter out unwanted entries. It takes a pointer

+// to an Info struct (not fully populated, currently

+// only Mountpoint is filled in), and returns two booleans:

+//  - skip: true if the entry should be skipped

+//  - stop: true if parsing should be stopped after the entry

+type FilterFunc func(*Info) (skip, stop bool)

+

+// PrefixFilter discards all entries whose mount points

+// do not start with a prefix specified

+func PrefixFilter(prefix string) FilterFunc {

+	return func(m *Info) (bool, bool) {

+		skip := !strings.HasPrefix(m.Mountpoint, prefix)

+		return skip, false

+	}

+}

+

+// SingleEntryFilter looks for a specific entry

+func SingleEntryFilter(mp string) FilterFunc {

+	return func(m *Info) (bool, bool) {

+		if m.Mountpoint == mp {

+			return false, true // don't skip, stop now

+		}

+		return true, false // skip, keep going

+	}

+}

+

+// GetMounts retrieves a list of mounts for the current running process,

+// with an optional filter applied (use nil for no filter).

+func GetMounts(f FilterFunc) ([]*Info, error) {

+	return parseMountTable(f)

 }

 // Mounted determines if a specified mountpoint has been mounted.

 // On Linux it looks at /proc/self/mountinfo.

 func Mounted(mountpoint string) (bool, error) {

-	entries, err := parseMountTable()

+	entries, err := GetMounts(SingleEntryFilter(mountpoint))

 	if err != nil {

 		return false, err

 	}

-	// Search the table for the mountpoint

-	for _, e := range entries {

-		if e.Mountpoint == mountpoint {

-			return true, nil

-		}

-	}

-	return false, nil

+	return len(entries) > 0, nil

 }

 // Mount will mount filesystem according to the specified configuration, on the

@@ -66,7 +88,7 @@ func Unmount(target string) error {

 // RecursiveUnmount unmounts the target and all mounts underneath, starting with

 // the deepsest mount first.

 func RecursiveUnmount(target string) error {

-	mounts, err := GetMounts()

+	mounts, err := parseMountTable(PrefixFilter(target))

 	if err != nil {

 		return err

 	}

@@ -77,9 +99,6 @@ func RecursiveUnmount(target string) error {

 	})

 	for i, m := range mounts {

-		if !strings.HasPrefix(m.Mountpoint, target) {

-			continue

-		}

 		logrus.Debugf("Trying to unmount %s", m.Mountpoint)

 		err = unmount(m.Mountpoint, mntDetach)

 		if err != nil {

@@ -129,7 +129,7 @@ func TestMountReadonly(t *testing.T) {

 }

 func TestGetMounts(t *testing.T) {

-	mounts, err := GetMounts()

+	mounts, err := GetMounts(nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -121,7 +121,7 @@ func ensureUnmount(t *testing.T, mnt string) {

 // validateMount checks that mnt has the given options

 func validateMount(t *testing.T, mnt string, opts, optional, vfs string) {

-	info, err := GetMounts()

+	info, err := GetMounts(nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -15,7 +15,7 @@ import (

 // Parse /proc/self/mountinfo because comparing Dev and ino does not work from

 // bind mounts.

-func parseMountTable() ([]*Info, error) {

+func parseMountTable(filter FilterFunc) ([]*Info, error) {

 	var rawEntries *C.struct_statfs

 	count := int(C.getmntinfo(&rawEntries, C.MNT_WAIT))

@@ -32,10 +32,24 @@ func parseMountTable() ([]*Info, error) {

 	var out []*Info

 	for _, entry := range entries {

 		var mountinfo Info

+		var skip, stop bool

 		mountinfo.Mountpoint = C.GoString(&entry.f_mntonname[0])

+

+		if filter != nil {

+			// filter out entries we're not interested in

+			skip, stop = filter(p)

+			if skip {

+				continue

+			}

+		}

+

 		mountinfo.Source = C.GoString(&entry.f_mntfromname[0])

 		mountinfo.Fstype = C.GoString(&entry.f_fstypename[0])

+

 		out = append(out, &mountinfo)

+		if stop {

+			break

+		}

 	}

 	return out, nil

 }

@@ -28,17 +28,17 @@ const (

 // Parse /proc/self/mountinfo because comparing Dev and ino does not work from

 // bind mounts

-func parseMountTable() ([]*Info, error) {

+func parseMountTable(filter FilterFunc) ([]*Info, error) {

 	f, err := os.Open("/proc/self/mountinfo")

 	if err != nil {

 		return nil, err

 	}

 	defer f.Close()

-	return parseInfoFile(f)

+	return parseInfoFile(f, filter)

 }

-func parseInfoFile(r io.Reader) ([]*Info, error) {

+func parseInfoFile(r io.Reader, filter FilterFunc) ([]*Info, error) {

 	var (

 		s   = bufio.NewScanner(r)

 		out = []*Info{}

@@ -53,6 +53,7 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {

 			p              = &Info{}

 			text           = s.Text()

 			optionalFields string

+			skip, stop     bool

 		)

 		if _, err := fmt.Sscanf(text, mountinfoFormat,

@@ -60,6 +61,13 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {

 			&p.Root, &p.Mountpoint, &p.Opts, &optionalFields); err != nil {

 			return nil, fmt.Errorf("Scanning '%s' failed: %s", text, err)

 		}

+		if filter != nil {

+			// filter out entries we're not interested in

+			skip, stop = filter(p)

+			if skip {

+				continue

+			}

+		}

 		// Safe as mountinfo encodes mountpoints with spaces as \040.

 		index := strings.Index(text, " - ")

 		postSeparatorFields := strings.Fields(text[index+3:])

@@ -75,6 +83,9 @@ func parseInfoFile(r io.Reader) ([]*Info, error) {

 		p.Source = postSeparatorFields[1]

 		p.VfsOpts = strings.Join(postSeparatorFields[2:], " ")

 		out = append(out, p)

+		if stop {

+			break

+		}

 	}

 	return out, nil

 }

@@ -89,5 +100,5 @@ func PidMountInfo(pid int) ([]*Info, error) {

 	}

 	defer f.Close()

-	return parseInfoFile(f)

+	return parseInfoFile(f, nil)

 }

@@ -5,6 +5,8 @@ package mount // import "github.com/docker/docker/pkg/mount"

 import (

 	"bytes"

 	"testing"

+

+	"github.com/gotestyourself/gotestyourself/assert"

 )

 const (

@@ -424,7 +426,7 @@ const (

 func TestParseFedoraMountinfo(t *testing.T) {

 	r := bytes.NewBuffer([]byte(fedoraMountinfo))

-	_, err := parseInfoFile(r)

+	_, err := parseInfoFile(r, nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -432,7 +434,7 @@ func TestParseFedoraMountinfo(t *testing.T) {

 func TestParseUbuntuMountinfo(t *testing.T) {

 	r := bytes.NewBuffer([]byte(ubuntuMountInfo))

-	_, err := parseInfoFile(r)

+	_, err := parseInfoFile(r, nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -440,7 +442,7 @@ func TestParseUbuntuMountinfo(t *testing.T) {

 func TestParseGentooMountinfo(t *testing.T) {

 	r := bytes.NewBuffer([]byte(gentooMountinfo))

-	_, err := parseInfoFile(r)

+	_, err := parseInfoFile(r, nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -448,7 +450,7 @@ func TestParseGentooMountinfo(t *testing.T) {

 func TestParseFedoraMountinfoFields(t *testing.T) {

 	r := bytes.NewBuffer([]byte(fedoraMountinfo))

-	infos, err := parseInfoFile(r)

+	infos, err := parseInfoFile(r, nil)

 	if err != nil {

 		t.Fatal(err)

 	}

@@ -474,3 +476,27 @@ func TestParseFedoraMountinfoFields(t *testing.T) {

 		t.Fatalf("expected %#v, got %#v", mi, infos[0])

 	}

 }

+

+func TestParseMountinfoFilters(t *testing.T) {

+	r := bytes.NewReader([]byte(fedoraMountinfo))

+

+	infos, err := parseInfoFile(r, SingleEntryFilter("/sys/fs/cgroup"))

+	assert.NilError(t, err)

+	assert.Equal(t, 1, len(infos))

+

+	r.Reset([]byte(fedoraMountinfo))

+	infos, err = parseInfoFile(r, SingleEntryFilter("nonexistent"))

+	assert.NilError(t, err)

+	assert.Equal(t, 0, len(infos))

+

+	r.Reset([]byte(fedoraMountinfo))

+	infos, err = parseInfoFile(r, PrefixFilter("/sys"))

+	assert.NilError(t, err)

+	// there are 18 entries starting with /sys in fedoraMountinfo

+	assert.Equal(t, 18, len(infos))

+

+	r.Reset([]byte(fedoraMountinfo))

+	infos, err = parseInfoFile(r, PrefixFilter("nonexistent"))

+	assert.NilError(t, err)

+	assert.Equal(t, 0, len(infos))

+}

@@ -7,6 +7,6 @@ import (

 	"runtime"

 )

-func parseMountTable() ([]*Info, error) {

+func parseMountTable(f FilterFunc) ([]*Info, error) {

 	return nil, fmt.Errorf("mount.parseMountTable is not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)

 }

@@ -1,6 +1,6 @@

 package mount // import "github.com/docker/docker/pkg/mount"

-func parseMountTable() ([]*Info, error) {

+func parseMountTable(f FilterFunc) ([]*Info, error) {

 	// Do NOT return an error!

 	return nil, nil

 }

@@ -66,7 +66,7 @@ func New(scope string, rootIDs idtools.IDPair) (*Root, error) {

 		return nil, err

 	}

-	mountInfos, err := mount.GetMounts()

+	mountInfos, err := mount.GetMounts(nil)

 	if err != nil {

 		logrus.Debugf("error looking up mounts for local volume cleanup: %v", err)

 	}

@@ -215,7 +215,7 @@ func TestCreateWithOpts(t *testing.T) {

 		}

 	}()

-	mountInfos, err := mount.GetMounts()

+	mountInfos, err := mount.GetMounts(nil)

 	if err != nil {

 		t.Fatal(err)

 	}