cephfs: add set/Get/List/Remove metadata utility functions

Add utility functions to set/Get/List/Remove PV/PVC/PVCNamespace metadata
on subvolume.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

internal/cephfs/core/metadata.go

@@ -0,0 +1,69 @@
+/*
+Copyright 2022 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package core
+
+import (
+	"fmt"
+	"strings"
+)
+
+// setMetadata sets custom metadata on the subvolume in a volume as a
+// key-value pair.
+func (s *subVolumeClient) setMetadata(key, value string) error {
+	fsa, err := s.conn.GetFSAdmin()
+	if err != nil {
+		return err
+	}
+
+	return fsa.SetMetadata(s.FsName, s.SubvolumeGroup, s.VolID, key, value)
+}
+
+// removeMetadata removes custom metadata set on the subvolume in a volume
+// using the metadata key.
+func (s *subVolumeClient) removeMetadata(key string) error {
+	fsa, err := s.conn.GetFSAdmin()
+	if err != nil {
+		return err
+	}
+
+	return fsa.RemoveMetadata(s.FsName, s.SubvolumeGroup, s.VolID, key)
+}
+
+// SetAllMetadata set all the metadata from arg parameters on Ssubvolume.
+func (s *subVolumeClient) SetAllMetadata(parameters map[string]string) error {
+	for k, v := range parameters {
+		err := s.setMetadata(k, v)
+		if err != nil {
+			return fmt.Errorf("failed to set metadata key %q, value %q on subvolume %v: %w", k, v, s, err)
+		}
+	}
+
+	return nil
+}
+
+// UnsetAllMetadata unset all the metadata from arg keys on subvolume.
+func (s *subVolumeClient) UnsetAllMetadata(keys []string) error {
+	for _, key := range keys {
+		err := s.removeMetadata(key)
+		// TODO: replace string comparison with errno.
+		if err != nil && !strings.Contains(err.Error(), "No such file or directory") {
+			return fmt.Errorf("failed to unset metadata key %q on subvolume %v: %w", key, s, err)
+		}
+	}
+
+	return nil
+}

internal/cephfs/core/volume.go

@@ -72,6 +72,11 @@ type SubVolumeClient interface {
 	CreateCloneFromSnapshot(ctx context.Context, snap Snapshot) error
 	// CleanupSnapshotFromSubvolume removes the snapshot from the subvolume.
 	CleanupSnapshotFromSubvolume(ctx context.Context, parentVol *SubVolume) error
+
+	// SetAllMetadata set all the metadata from arg parameters on Ssubvolume.
+	SetAllMetadata(parameters map[string]string) error
+	// UnsetAllMetadata unset all the metadata from arg keys on subvolume.
+	UnsetAllMetadata(keys []string) error
 }
 
 // subVolumeClient implements SubVolumeClient interface.