// 清除thin pool
1.1 func (d *Driver) Cleanup() error {
// 停止thin pool
err := d.DeviceSet.Shutdown()
return err
}
// 当载入新镜像时，加入一个新thin device
// id为containerid或imageid
1.2 func (d *Driver) Create(id, parent string) error {
if err := d.DeviceSet.AddDevice(id, parent); err != nil {
return err
}
return nil
}
// 删除thin device
1.3 func (d *Driver) Remove(id string) error {
//检查thin device是否存在
if !d.DeviceSet.HasDevice(id) {
return nil
}
//通过id从thin pool中删除设备
if err := d.DeviceSet.DeleteDevice(id); err != nil {
return err
}
//mp为/var/lib/docker/devicemapper/mnt/$id
mp := path.Join(d.home, "mnt", id)
//删除文件夹下全部的文件
if err := os.RemoveAll(mp); err != nil && !os.IsNotExist(err) {
return err
}
return nil
}
// 挂载thin device到/var/lib/docker/devicemapper/mnt/$id文件夹下
1.4 func (d *Driver) Get(id, mountLabel string) (string, error) {
//mp=/var/lib/docker/devicemapper/mnt/$id
mp := path.Join(d.home, "mnt", id)
//创建文件夹/var/lib/docker/devicemapper/mnt/$id
if err := os.MkdirAll(mp, 0755); err != nil && !os.IsExist(err) {
return "", err
}
//挂载thin device到/var/lib/docker/devicemapper/mnt/$id
if err := d.DeviceSet.MountDevice(id, mp, mountLabel); err != nil {
return "", err
}
//创建rootfs到/var/lib/docker/devicemapper/mnt/$id/rootfs
rootFs := path.Join(mp, "rootfs")
if err := os.MkdirAll(rootFs, 0755); err != nil && !os.IsExist(err) {
d.DeviceSet.UnmountDevice(id)
return "", err
}
//创建id
idFile := path.Join(mp, "id")
if _, err := os.Stat(idFile); err != nil && os.IsNotExist(err) {
if err := ioutil.WriteFile(idFile, []byte(id), 0600); err != nil {
d.DeviceSet.UnmountDevice(id)
return "", err
}
}
//返回/var/lib/docker/devicemapper/mnt/$id/rootfs文件夹
return rootFs, nil
}
// 从/var/lib/docker/devicemapper/mnt/$id下解挂设备
1.5 func (d *Driver) Put(id string) {
if err := d.DeviceSet.UnmountDevice(id); err != nil {
utils.Errorf("Warning: error unmounting device %s: %s\n", id, err)
}
}
// 推断$id所相应的设备是否存在
1.6 func (d *Driver) Exists(id string) bool {
return d.DeviceSet.HasDevice(id)
}