Improvements to the original sharing implementation.

- Print the mount table as in /proc/self/mountinfo
- Do not exit prematurely when one of the ipc mounts doesn't exist.
- Do not exit prematurely when one of the ipc mounts cannot be unmounted.
- Add a unit test to see if the cleanup really works.
- Use syscall.MNT_DETACH to cleanup mounts after a crash.
- Unmount IPC mounts when the daemon unregisters an old running container.

Signed-off-by: David Calavera <david.calavera@gmail.com>

daemon/daemon_linux.go

@@ -2,12 +2,13 @@ package daemon
 
 import (
 	"bufio"
+	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/docker/docker/pkg/mount"
 )
 
 // cleanupMounts umounts shm/mqueue mounts for old containers
@@ -19,17 +20,24 @@ func (daemon *Daemon) cleanupMounts() error {
 	}
 	defer f.Close()
 
-	sc := bufio.NewScanner(f)
+	return daemon.cleanupMountsFromReader(f, detachMounted)
+}
+
+func (daemon *Daemon) cleanupMountsFromReader(reader io.Reader, unmount func(target string) error) error {
+	sc := bufio.NewScanner(reader)
+	var errors []string
 	for sc.Scan() {
 		line := sc.Text()
-		fields := strings.Split(line, " ")
+		fields := strings.Fields(line)
 		if strings.HasPrefix(fields[4], daemon.repository) {
+			logrus.Debugf("Mount base: %v, repository %s", fields[4], daemon.repository)
 			mnt := fields[4]
 			mountBase := filepath.Base(mnt)
 			if mountBase == "mqueue" || mountBase == "shm" {
-				logrus.Debugf("Unmounting %+v", mnt)
-				if err := mount.Unmount(mnt); err != nil {
-					return err
+				logrus.Debugf("Unmounting %v", mnt)
+				if err := unmount(mnt); err != nil {
+					logrus.Error(err)
+					errors = append(errors, err.Error())
 				}
 			}
 		}
@@ -39,6 +47,10 @@ func (daemon *Daemon) cleanupMounts() error {
 		return err
 	}
 
+	if len(errors) > 0 {
+		return fmt.Errorf("Error cleaningup mounts:\n%v", strings.Join(errors, "\n"))
+	}
+
 	logrus.Debugf("Cleaning up old shm/mqueue mounts: done.")
 	return nil
 }