expose resize

btrfs.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strconv"
 	"syscall"
 )
 
@@ -242,3 +243,22 @@ func (f *FS) Balance(flags BalanceFlags) (BalanceProgress, error) {
 	err := iocBalanceV2(f.f, &args)
 	return args.stat, err
 }
+
+func (f *FS) Resize(size int64) error {
+	amount := strconv.FormatInt(size, 10)
+	args := &btrfs_ioctl_vol_args{}
+	args.SetName(amount)
+	if err := iocResize(f.f, args); err != nil {
+		return fmt.Errorf("resize failed: %v", err)
+	}
+	return nil
+}
+
+func (f *FS) ResizeToMax() error {
+	args := &btrfs_ioctl_vol_args{}
+	args.SetName("max")
+	if err := iocResize(f.f, args); err != nil {
+		return fmt.Errorf("resize failed: %v", err)
+	}
+	return nil
+}

btrfs_test.go

@@ -3,6 +3,7 @@ package btrfs
 import (
 	"github.com/dennwc/btrfs/test"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -215,3 +216,62 @@ func TestCloneFile(t *testing.T) {
 		t.Fatalf("wrong data returned: %q", string(buf))
 	}
 }
+
+func TestResize(t *testing.T) {
+	dir, err := ioutil.TempDir("", "btrfs_data_")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+	fname := filepath.Join(dir, "data")
+	if err = btrfstest.Mkfs(fname, sizeDef); err != nil {
+		t.Fatal(err)
+	}
+	mnt := filepath.Join(dir, "mnt")
+	if err = os.MkdirAll(mnt, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err = btrfstest.Mount(mnt, fname); err != nil {
+		t.Fatal(err)
+	}
+	defer btrfstest.Unmount(mnt)
+
+	fs, err := Open(mnt, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	st, err := fs.Usage()
+	fs.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = btrfstest.Unmount(mnt); err != nil {
+		t.Fatal(err)
+	}
+	var newSize int64 = sizeDef
+	newSize = int64(float64(newSize) * 1.1)
+	if err = os.Truncate(fname, newSize); err != nil {
+		t.Fatal(err)
+	}
+	if err = btrfstest.Mount(mnt, fname); err != nil {
+		t.Fatal(err)
+	}
+
+	fs, err = Open(mnt, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer fs.Close()
+
+	if err = fs.ResizeToMax(); err != nil {
+		t.Fatal(err)
+	}
+
+	st2, err := fs.Usage()
+	if err != nil {
+		t.Fatal(err)
+	} else if st.Total >= st2.Total {
+		t.Fatal("to resized:", st.Total, st2.Total)
+	}
+}

ioctl_h.go

@@ -60,6 +60,11 @@ type btrfs_ioctl_vol_args struct {
 	name [volNameMax + 1]byte
 }
 
+func (arg *btrfs_ioctl_vol_args) SetName(name string) {
+	n := copy(arg.name[:], name)
+	arg.name[n] = 0
+}
+
 type btrfs_qgroup_limit struct {
 	flags          uint64
 	max_referenced uint64
@@ -625,8 +630,8 @@ func iocDefrag(f *os.File, out *btrfs_ioctl_vol_args) error {
 	return ioctl.Do(f, _BTRFS_IOC_DEFRAG, out)
 }
 
-func iocResize(f *os.File, out *btrfs_ioctl_vol_args) error {
-	return ioctl.Do(f, _BTRFS_IOC_RESIZE, out)
+func iocResize(f *os.File, in *btrfs_ioctl_vol_args) error {
+	return ioctl.Do(f, _BTRFS_IOC_RESIZE, in)
 }
 
 func iocScanDev(f *os.File, out *btrfs_ioctl_vol_args) error {

test/btrfstest.go

@@ -52,6 +52,21 @@ func Mount(mount string, file string) error {
 	return nil
 }
 
+func Unmount(mount string) error {
+	for i := 0; i < 5; i++ {
+		if err := run("umount", mount); err == nil {
+			break
+		} else {
+			if strings.Contains(err.Error(), "busy") {
+				time.Sleep(time.Second)
+			} else {
+				break
+			}
+		}
+	}
+	return nil
+}
+
 func New(t testing.TB, size int64) (string, func()) {
 	f, err := ioutil.TempFile("", "btrfs_vol")
 	if err != nil {
@@ -85,17 +100,8 @@ func New(t testing.TB, size int64) (string, func()) {
 		if done {
 			return
 		}
-		for i := 0; i < 5; i++ {
-			if err := run("umount", mount); err == nil {
-				break
-			} else {
-				log.Println("umount failed:", err)
-				if strings.Contains(err.Error(), "busy") {
-					time.Sleep(time.Second)
-				} else {
-					break
-				}
-			}
+		if err := Unmount(mount); err != nil {
+			log.Println("umount failed:", err)
 		}
 		if err := os.Remove(mount); err != nil {
 			log.Println("cleanup failed:", err)