cephfs admin: add ResizeSubVolume and supporting types

Add a function for resizing a subvolume as well as types needed to
create the JSON command and parse the response JSON. The newSize
argument can be passed a numeric value (as a ByteCount) or the special
constant `Infinite` much like the ceph cli command. This is accomplished
using the interface type `NewSize`.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

cephfs/admin/bytecount.go

@@ -10,3 +10,26 @@ const (
 	gibiByte           = 1024 * mebiByte
 	tebiByte           = 1024 * gibiByte
 )
+
+// newSizeValue returns a size value as a string, as needed by the subvolume
+// resize command json.
+func (bc ByteCount) newSizeValue() string {
+	return uint64String(uint64(bc))
+}
+
+// NewSize interface values can be used to change the size of a volume.
+type NewSize interface {
+	newSizeValue() string
+}
+
+// specialSize is a custom non-numeric new size value.
+type specialSize string
+
+// newSizeValue for a specialSize returns the literal string.
+func (s specialSize) newSizeValue() string {
+	return string(s)
+}
+
+// Infinite is a special NewSize value that can be used to clear size limits on
+// a subvolume.
+const Infinite = specialSize("infinite")

cephfs/admin/fsadmin.go

@@ -124,3 +124,10 @@ func modeString(m int, force bool) string {
 	}
 	return ""
 }
+
+// uint64String converts a uint64 to a string. Some of the ceph json commands
+// can take a string or "int" (as a string). This is a common function for
+// doing that conversion.
+func uint64String(v uint64) string {
+	return strconv.FormatUint(uint64(v), 10)
+}

cephfs/admin/subvolume.go

@@ -93,3 +93,45 @@ func (fsa *FSAdmin) RemoveSubVolume(volume, group, name string) error {
 	}
 	return checkEmptyResponseExpected(fsa.marshalMgrCommand(m))
 }
+
+type subVolumeResizeFields struct {
+	Prefix    string `json:"prefix"`
+	Format    string `json:"format"`
+	VolName   string `json:"vol_name"`
+	GroupName string `json:"group_name,omitempty"`
+	SubName   string `json:"sub_name"`
+	NewSize   string `json:"new_size"`
+	NoShrink  bool   `json:"no_shrink"`
+}
+
+// SubVolumeResizeResult reports the size values returned by the
+// ResizeSubVolume function, as reported by Ceph.
+type SubVolumeResizeResult struct {
+	BytesUsed    ByteCount `json:"bytes_used"`
+	BytesQuota   ByteCount `json:"bytes_quota"`
+	BytesPercent string    `json:"bytes_pcent"`
+}
+
+// ResizeSubVolume will resize a CephFS subvolume. The newSize value may be a
+// ByteCount or the special Infinite constant. Setting noShrink to true will
+// prevent reducing the size of the volume below the current used size.
+func (fsa *FSAdmin) ResizeSubVolume(
+	volume, group, name string,
+	newSize NewSize, noShrink bool) (*SubVolumeResizeResult, error) {
+
+	f := &subVolumeResizeFields{
+		Prefix:    "fs subvolume resize",
+		Format:    "json",
+		VolName:   volume,
+		GroupName: group,
+		SubName:   name,
+		NewSize:   newSize.newSizeValue(),
+		NoShrink:  noShrink,
+	}
+	var result []*SubVolumeResizeResult
+	r, s, err := fsa.marshalMgrCommand(f)
+	if err := unmarshalResponseJSON(r, s, err, &result); err != nil {
+		return nil, err
+	}
+	return result[0], nil
+}

cephfs/admin/subvolume_test.go

@@ -130,3 +130,44 @@ func TestRemoveSubVolume(t *testing.T) {
 		assert.Equal(t, []string{}, lsv)
 	}
 }
+
+func TestResizeSubVolume(t *testing.T) {
+	fsa := getFSAdmin(t)
+	volume := "cephfs"
+	group := "sizedGroup"
+	subname := "sizeMe1"
+
+	err := fsa.CreateSubVolumeGroup(volume, group, nil)
+	assert.NoError(t, err)
+	defer func() {
+		err := fsa.RemoveSubVolumeGroup(volume, group)
+		assert.NoError(t, err)
+	}()
+
+	svopts := &SubVolumeOptions{
+		Mode: 0777,
+		Size: 20 * gibiByte,
+	}
+	err = fsa.CreateSubVolume(volume, group, subname, svopts)
+	assert.NoError(t, err)
+	defer func() {
+		err := fsa.RemoveSubVolume(volume, group, subname)
+		assert.NoError(t, err)
+	}()
+
+	lsv, err := fsa.ListSubVolumes(volume, group)
+	assert.NoError(t, err)
+	assert.Contains(t, lsv, subname)
+
+	rr, err := fsa.ResizeSubVolume(volume, group, subname, 30*gibiByte, false)
+	assert.NoError(t, err)
+	assert.NotNil(t, rr)
+
+	rr, err = fsa.ResizeSubVolume(volume, group, subname, 10*gibiByte, true)
+	assert.NoError(t, err)
+	assert.NotNil(t, rr)
+
+	rr, err = fsa.ResizeSubVolume(volume, group, subname, Infinite, true)
+	assert.NoError(t, err)
+	assert.NotNil(t, rr)
+}