// Try to mount using the aufs fast path, if this fails then
// append ro layers.
func (a *Driver) tryMount(ro []string, rw, target, mountLabel string) (err error) {
var (
rwBranch = fmt.Sprintf("%s=rw", rw)
roBranches = fmt.Sprintf("%s=ro+wh:", strings.Join(ro, "=ro+wh:"))
data = label.FormatMountLabel(fmt.Sprintf("br:%v:%v,xino=/dev/shm/aufs.xino", rwBranch, roBranches), mountLabel)
)
return mount("none", target, "aufs", 0, data)
}
func (devices *DeviceSet) MountDevice(hash, path, mountLabel string) error {
info, err := devices.lookupDevice(hash)
if err != nil {
return err
}
info.lock.Lock()
defer info.lock.Unlock()
devices.Lock()
defer devices.Unlock()
if info.mountCount > 0 {
if path != info.mountPath {
return fmt.Errorf("Trying to mount devmapper device in multple places (%s, %s)", info.mountPath, path)
}
info.mountCount++
return nil
}
if err := devices.activateDeviceIfNeeded(info); err != nil {
return fmt.Errorf("Error activating devmapper device for '%s': %s", hash, err)
}
var flags uintptr = syscall.MS_MGC_VAL
fstype, err := ProbeFsType(info.DevName())
if err != nil {
return err
}
options := ""
if fstype == "xfs" {
// XFS needs nouuid or it can't mount filesystems with the same fs
options = joinMountOptions(options, "nouuid")
}
options = joinMountOptions(options, devices.mountOptions)
options = joinMountOptions(options, label.FormatMountLabel("", mountLabel))
err = syscall.Mount(info.DevName(), path, fstype, flags, joinMountOptions("discard", options))
if err != nil && err == syscall.EINVAL {
err = syscall.Mount(info.DevName(), path, fstype, flags, options)
}
if err != nil {
return fmt.Errorf("Error mounting '%s' on '%s': %s", info.DevName(), path, err)
}
info.mountCount = 1
info.mountPath = path
return nil
}
func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err error) {
defer func() {
if err != nil {
Unmount(target)
}
}()
if err = a.tryMount(ro, rw, target, mountLabel); err != nil {
if err = a.mountRw(rw, target, mountLabel); err != nil {
return
}
for _, layer := range ro {
data := label.FormatMountLabel(fmt.Sprintf("append:%s=ro+wh", layer), mountLabel)
if err = mount("none", target, "aufs", MsRemount, data); err != nil {
return
}
}
}
return
}
// TODO: this is crappy right now and should be cleaned up with a better way of handling system and
// standard bind mounts allowing them to be more dynamic
func newSystemMounts(rootfs, mountLabel string, sysReadonly bool, mounts Mounts) []mount {
systemMounts := []mount{
{source: "proc", path: filepath.Join(rootfs, "proc"), device: "proc", flags: defaultMountFlags},
{source: "tmpfs", path: filepath.Join(rootfs, "dev"), device: "tmpfs", flags: syscall.MS_NOSUID | syscall.MS_STRICTATIME, data: label.FormatMountLabel("mode=755", mountLabel)},
{source: "shm", path: filepath.Join(rootfs, "dev", "shm"), device: "tmpfs", flags: defaultMountFlags, data: label.FormatMountLabel("mode=1777,size=65536k", mountLabel)},
{source: "devpts", path: filepath.Join(rootfs, "dev", "pts"), device: "devpts", flags: syscall.MS_NOSUID | syscall.MS_NOEXEC, data: label.FormatMountLabel("newinstance,ptmxmode=0666,mode=620,gid=5", mountLabel)},
}
sysMountFlags := defaultMountFlags
if sysReadonly {
sysMountFlags |= syscall.MS_RDONLY
}
systemMounts = append(systemMounts, mount{source: "sysfs", path: filepath.Join(rootfs, "sys"), device: "sysfs", flags: sysMountFlags})
return systemMounts
}
func (a *Driver) mountRw(rw, target, mountLabel string) error {
data := label.FormatMountLabel(fmt.Sprintf("br:%s,xino=/dev/shm/aufs.xino", rw), mountLabel)
return mount("none", target, "aufs", 0, data)
}