cephfs admin: add SubVolumeSnapshotInfo function for octopus

Add the new to octopus call for subvolume snapshot info.  Two fields
appear to return strings "yes"/"no", so could possibly have been
converted to booleans. In the chance that other string values get
returned and simplicity I left them as strings. If we need to, we can add
convenience funcs to return bools later.

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

cephfs/admin/subvolume_octopus.go

@@ -0,0 +1,38 @@
+// +build octopus
+
+package admin
+
+// SubVolumeSnapshotInfo reports various informational values about a subvolume.
+type SubVolumeSnapshotInfo struct {
+	CreatedAt        TimeStamp `json:"created_at"`
+	DataPool         string    `json:"data_pool"`
+	HasPendingClones string    `json:"has_pending_clones"`
+	Protected        string    `json:"protected"`
+	Size             ByteCount `json:"size"`
+}
+
+func parseSubVolumeSnapshotInfo(r []byte, s string, err error) (*SubVolumeSnapshotInfo, error) {
+	var info SubVolumeSnapshotInfo
+	if err := unmarshalResponseJSON(r, s, err, &info); err != nil {
+		return nil, err
+	}
+	return &info, nil
+}
+
+// SubVolumeSnapshotInfo returns information about the specified subvolume snapshot.
+//
+// Similar To:
+//  ceph fs subvolume snapshot info <volume> --group-name=<group> <subvolume> <name>
+func (fsa *FSAdmin) SubVolumeSnapshotInfo(volume, group, subvolume, name string) (*SubVolumeSnapshotInfo, error) {
+	m := map[string]string{
+		"prefix":    "fs subvolume snapshot info",
+		"vol_name":  volume,
+		"sub_name":  subvolume,
+		"snap_name": name,
+		"format":    "json",
+	}
+	if group != NoGroup {
+		m["group_name"] = group
+	}
+	return parseSubVolumeSnapshotInfo(fsa.marshalMgrCommand(m))
+}

cephfs/admin/subvolume_octopus_test.go

@@ -0,0 +1,92 @@
+// +build octopus
+
+package admin
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var sampleSubVolumeSnapshoInfo1 = []byte(`
+{
+    "created_at": "2020-09-11 17:40:12.035792",
+    "data_pool": "cephfs_data",
+    "has_pending_clones": "no",
+    "protected": "yes",
+    "size": 0
+}
+`)
+
+func TestParseSubVolumeSnapshotInfo(t *testing.T) {
+	t.Run("error", func(t *testing.T) {
+		_, err := parseSubVolumeSnapshotInfo(nil, "", errors.New("flub"))
+		assert.Error(t, err)
+		assert.Equal(t, "flub", err.Error())
+	})
+	t.Run("statusSet", func(t *testing.T) {
+		_, err := parseSubVolumeSnapshotInfo(nil, "unexpected!", nil)
+		assert.Error(t, err)
+	})
+	t.Run("badJSON", func(t *testing.T) {
+		_, err := parseSubVolumeSnapshotInfo([]byte("_XxXxX"), "", nil)
+		assert.Error(t, err)
+	})
+	t.Run("ok", func(t *testing.T) {
+		info, err := parseSubVolumeSnapshotInfo(sampleSubVolumeSnapshoInfo1, "", nil)
+		assert.NoError(t, err)
+		if assert.NotNil(t, info) {
+			assert.Equal(t, "cephfs_data", info.DataPool)
+			assert.EqualValues(t, 0, info.Size)
+			assert.Equal(t, 2020, info.CreatedAt.Year())
+			assert.Equal(t, "yes", info.Protected)
+			assert.Equal(t, "no", info.HasPendingClones)
+		}
+	})
+}
+
+func TestSubVolumeSnapshotInfo(t *testing.T) {
+	fsa := getFSAdmin(t)
+	volume := "cephfs"
+	group := "20000leagues"
+	subname := "poulp"
+	snapname1 := "t1"
+	snapname2 := "nope"
+
+	err := fsa.CreateSubVolumeGroup(volume, group, nil)
+	assert.NoError(t, err)
+	defer func() {
+		err := fsa.RemoveSubVolumeGroup(volume, group)
+		assert.NoError(t, err)
+	}()
+
+	svopts := &SubVolumeOptions{
+		Mode: 0750,
+		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)
+	}()
+
+	err = fsa.CreateSubVolumeSnapshot(volume, group, subname, snapname1)
+	assert.NoError(t, err)
+	defer func() {
+		err := fsa.RemoveSubVolumeSnapshot(volume, group, subname, snapname1)
+		assert.NoError(t, err)
+	}()
+
+	sinfo, err := fsa.SubVolumeSnapshotInfo(volume, group, subname, snapname1)
+	assert.NoError(t, err)
+	assert.NotNil(t, sinfo)
+	assert.EqualValues(t, 0, sinfo.Size)
+	assert.Equal(t, "cephfs_data", sinfo.DataPool)
+	assert.GreaterOrEqual(t, 2020, sinfo.CreatedAt.Year())
+
+	sinfo, err = fsa.SubVolumeSnapshotInfo(volume, group, subname, snapname2)
+	assert.Error(t, err)
+	assert.Nil(t, sinfo)
+}