func aufsMount(ro []string, rw, target, mountLabel string) (err error) {
defer func() {
if err != nil {
aufsUnmount(target)
}
}()
// Mount options are clipped to page size(4096 bytes). If there are more
// layers then these are remounted individually using append.
offset := 54
if useDirperm() {
offset += len("dirperm1")
}
b := make([]byte, syscall.Getpagesize()-len(mountLabel)-offset) // room for xino & mountLabel
bp := copy(b, fmt.Sprintf("br:%s=rw", rw))
firstMount := true
i := 0
for {
for ; i < len(ro); i++ {
layer := fmt.Sprintf(":%s=ro+wh", ro[i])
if firstMount {
if bp+len(layer) > len(b) {
break
}
bp += copy(b[bp:], layer)
} else {
data := utils.FormatMountLabel(fmt.Sprintf("append%s", layer), mountLabel)
if err = syscall.Mount("none", target, "aufs", MsRemount, data); err != nil {
return
}
}
}
if firstMount {
opts := "dio,xino=/dev/shm/aufs.xino"
if useDirperm() {
opts += ",dirperm1"
}
data := utils.FormatMountLabel(fmt.Sprintf("%s,%s", string(b[:bp]), opts), mountLabel)
if err = syscall.Mount("none", target, "aufs", 0, data); err != nil {
return
}
firstMount = false
}
if i == len(ro) {
break
}
}
return
}
func MountContainerToSharedDir(containerId, rootDir, sharedDir, mountLabel string) (string, error) {
var (
mountPoint = path.Join(sharedDir, containerId, "rootfs")
upperDir = path.Join(rootDir, containerId, "upper")
workDir = path.Join(rootDir, containerId, "work")
)
if _, err := os.Stat(mountPoint); err != nil {
if err = os.MkdirAll(mountPoint, 0755); err != nil {
return "", err
}
}
lowerId, err := ioutil.ReadFile(path.Join(rootDir, containerId) + "/lower-id")
if err != nil {
return "", err
}
lowerDir := path.Join(rootDir, string(lowerId), "root")
params := fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", lowerDir, upperDir, workDir)
if err := syscall.Mount("overlay", mountPoint, "overlay", 0, utils.FormatMountLabel(params, mountLabel)); err != nil {
return "", fmt.Errorf("error creating overlay mount to %s: %v", mountPoint, err)
}
return mountPoint, nil
}