cephfs: add set/Remove subvolume snapshot metadata utility functions

Add utility functions to set/Remove
snapshot-name/snapshot-namespace/snapshotcontent-name metadata on
subvolume snapshots.

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

internal/cephfs/core/snapshot.go

@@ -51,6 +51,12 @@ type SnapshotClient interface {
 	UnprotectSnapshot(ctx context.Context) error
 	// CloneSnapshot clones the snapshot of the subvolume.
 	CloneSnapshot(ctx context.Context, cloneVolOptions *SubVolume) error
+	// SetAllSnapshotMetadata set all the metadata from arg parameters on
+	// subvolume snapshot.
+	SetAllSnapshotMetadata(parameters map[string]string) error
+	// UnsetAllSnapshotMetadata unset all the metadata from arg keys on
+	// subvolume snapshot.
+	UnsetAllSnapshotMetadata(keys []string) error
 }
 
 // snapshotClient is the implementation of SnapshotClient interface.

internal/cephfs/core/snapshot_metadata.go

@@ -0,0 +1,73 @@
+/*
+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"
+)
+
+// setSnapshotMetadata sets custom metadata on the subvolume snapshot in a
+// volume as a key-value pair.
+func (s *snapshotClient) setSnapshotMetadata(key, value string) error {
+	fsa, err := s.conn.GetFSAdmin()
+	if err != nil {
+		return err
+	}
+
+	return fsa.SetSnapshotMetadata(s.FsName, s.SubvolumeGroup, s.VolID, s.SnapshotID, key, value)
+}
+
+// removeSnapshotMetadata removes custom metadata set on the subvolume
+// snapshot in a volume using the metadata key.
+func (s *snapshotClient) removeSnapshotMetadata(key string) error {
+	fsa, err := s.conn.GetFSAdmin()
+	if err != nil {
+		return err
+	}
+
+	return fsa.RemoveSnapshotMetadata(s.FsName, s.SubvolumeGroup, s.VolID, s.SnapshotID, key)
+}
+
+// SetAllSnapshotMetadata set all the metadata from arg parameters on
+// subvolume snapshot.
+func (s *snapshotClient) SetAllSnapshotMetadata(parameters map[string]string) error {
+	for k, v := range parameters {
+		err := s.setSnapshotMetadata(k, v)
+		if err != nil {
+			return fmt.Errorf("failed to set metadata key %q, value %q on subvolume snapshot %s %s in fs %s: %w",
+				k, v, s.SnapshotID, s.VolID, s.FsName, err)
+		}
+	}
+
+	return nil
+}
+
+// UnsetAllSnapshotMetadata unset all the metadata from arg keys on subvolume
+// snapshot.
+func (s *snapshotClient) UnsetAllSnapshotMetadata(keys []string) error {
+	for _, key := range keys {
+		err := s.removeSnapshotMetadata(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 snapshot %s %s in fs %s: %w",
+				key, s.SnapshotID, s.VolID, s.FsName, err)
+		}
+	}
+
+	return nil
+}