| // +build linux,amd64 |
| |
| package btrfs |
| |
| /* |
| #include <stdlib.h> |
| #include <dirent.h> |
| #include <btrfs/ioctl.h> |
| */ |
| import "C" |
| |
| import ( |
| "fmt" |
| "github.com/dotcloud/docker/graphdriver" |
| "os" |
| "path" |
| "syscall" |
| "unsafe" |
| ) |
| |
| func init() { |
| graphdriver.Register("btrfs", Init) |
| } |
| |
| func Init(home string) (graphdriver.Driver, error) { |
| rootdir := path.Dir(home) |
| |
| var buf syscall.Statfs_t |
| if err := syscall.Statfs(rootdir, &buf); err != nil { |
| return nil, err |
| } |
| |
| if buf.Type != 0x9123683E { |
| return nil, fmt.Errorf("%s is not a btrfs filesystem", rootdir) |
| } |
| |
| return &Driver{ |
| home: home, |
| }, nil |
| } |
| |
| type Driver struct { |
| home string |
| } |
| |
| func (d *Driver) String() string { |
| return "btrfs" |
| } |
| |
| func (d *Driver) Status() [][2]string { |
| return nil |
| } |
| |
| func (d *Driver) Cleanup() error { |
| return nil |
| } |
| |
| func free(p *C.char) { |
| C.free(unsafe.Pointer(p)) |
| } |
| |
| func openDir(path string) (*C.DIR, error) { |
| Cpath := C.CString(path) |
| defer free(Cpath) |
| |
| dir := C.opendir(Cpath) |
| if dir == nil { |
| return nil, fmt.Errorf("Can't open dir") |
| } |
| return dir, nil |
| } |
| |
| func closeDir(dir *C.DIR) { |
| if dir != nil { |
| C.closedir(dir) |
| } |
| } |
| |
| func getDirFd(dir *C.DIR) uintptr { |
| return uintptr(C.dirfd(dir)) |
| } |
| |
| func subvolCreate(path, name string) error { |
| dir, err := openDir(path) |
| if err != nil { |
| return err |
| } |
| defer closeDir(dir) |
| |
| var args C.struct_btrfs_ioctl_vol_args |
| for i, c := range []byte(name) { |
| args.name[i] = C.char(c) |
| } |
| |
| _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SUBVOL_CREATE, |
| uintptr(unsafe.Pointer(&args))) |
| if errno != 0 { |
| return fmt.Errorf("Failed to create btrfs subvolume: %v", errno.Error()) |
| } |
| return nil |
| } |
| |
| func subvolSnapshot(src, dest, name string) error { |
| srcDir, err := openDir(src) |
| if err != nil { |
| return err |
| } |
| defer closeDir(srcDir) |
| |
| destDir, err := openDir(dest) |
| if err != nil { |
| return err |
| } |
| defer closeDir(destDir) |
| |
| var args C.struct_btrfs_ioctl_vol_args_v2 |
| args.fd = C.__s64(getDirFd(srcDir)) |
| for i, c := range []byte(name) { |
| args.name[i] = C.char(c) |
| } |
| |
| _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(destDir), C.BTRFS_IOC_SNAP_CREATE_V2, |
| uintptr(unsafe.Pointer(&args))) |
| if errno != 0 { |
| return fmt.Errorf("Failed to create btrfs snapshot: %v", errno.Error()) |
| } |
| return nil |
| } |
| |
| func subvolDelete(path, name string) error { |
| dir, err := openDir(path) |
| if err != nil { |
| return err |
| } |
| defer closeDir(dir) |
| |
| var args C.struct_btrfs_ioctl_vol_args |
| for i, c := range []byte(name) { |
| args.name[i] = C.char(c) |
| } |
| |
| _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, getDirFd(dir), C.BTRFS_IOC_SNAP_DESTROY, |
| uintptr(unsafe.Pointer(&args))) |
| if errno != 0 { |
| return fmt.Errorf("Failed to destroy btrfs snapshot: %v", errno.Error()) |
| } |
| return nil |
| } |
| |
| func (d *Driver) subvolumesDir() string { |
| return path.Join(d.home, "subvolumes") |
| } |
| |
| func (d *Driver) subvolumesDirId(id string) string { |
| return path.Join(d.subvolumesDir(), id) |
| } |
| |
| func (d *Driver) Create(id string, parent string) error { |
| subvolumes := path.Join(d.home, "subvolumes") |
| if err := os.MkdirAll(subvolumes, 0700); err != nil { |
| return err |
| } |
| if parent == "" { |
| if err := subvolCreate(subvolumes, id); err != nil { |
| return err |
| } |
| } else { |
| parentDir, err := d.Get(parent) |
| if err != nil { |
| return err |
| } |
| if err := subvolSnapshot(parentDir, subvolumes, id); err != nil { |
| return err |
| } |
| } |
| return nil |
| } |
| |
| func (d *Driver) Remove(id string) error { |
| dir := d.subvolumesDirId(id) |
| if _, err := os.Stat(dir); err != nil { |
| return err |
| } |
| if err := subvolDelete(d.subvolumesDir(), id); err != nil { |
| return err |
| } |
| return os.RemoveAll(dir) |
| } |
| |
| func (d *Driver) Get(id string) (string, error) { |
| dir := d.subvolumesDirId(id) |
| st, err := os.Stat(dir) |
| if err != nil { |
| return "", err |
| } |
| |
| if !st.IsDir() { |
| return "", fmt.Errorf("%s: not a directory", dir) |
| } |
| |
| return dir, nil |
| } |
| |
| func (d *Driver) Put(id string) { |
| // Get() creates no runtime resources (like e.g. mounts) |
| // so this doesn't need to do anything. |
| } |
| |
| func (d *Driver) Exists(id string) bool { |
| dir := d.subvolumesDirId(id) |
| _, err := os.Stat(dir) |
| return err == nil |
| } |