rbd: Implement snapshot and clone from snapshot

This Adds a support for create,delete snapshot
and creating a new rbd image from the snapshot.

* Create a snapshot

* Create a temporary snapshot from the parent volume
* Clone a new image from a temporary snapshot with options
  --rbd-default-clone-format 2 --image-feature layering,deep-flatten
* Delete temporary snapshot created
* Create a new snapshot from cloned image
* Check the image chain depth, if the Softlimit is reached Add a
  task Flatten the cloned image and return success. if the depth
  is reached hard limit Add a task Flatten the cloned image and
  return snapshot status ready as false

```bash
1) rbd snap create <RBD image for src k8s volume>@<random snap name>
2) rbd clone --rbd-default-clone-format 2 --image-feature
   layering,deep-flatten <RBD image for src k8s volume>@<random snap>
   <RBD image for temporary snap image>
3) rbd snap rm <RBD image for src k8s volume>@<random snap name>
4) rbd snap rm <RBD image for temporary snap image>@<random snap name>
5) check the depth, if the depth is greater than configured hard
   limit add a task to flatten the cloned image return snapshot status
   ready as false if the depth is greater than soft limit add a task
   to flatten the image and return success
```

* Create a clone from snapshot

* Clone a new image from the snapshot with user-provided options
* Check the depth(n) of the cloned image if n>=(hard limit)
  Add task to flatten the image and return ABORT (to avoid image leak)

```bash
1) rbd clone --rbd-default-clone-format 2 --image-feature
   <k8s dst vol config> <RBD image for temporary snap image>@<random snap name>
    <RBD image for k8s dst vol>
2) check the depth, if the depth is greater than configured hard limit
    add a task to flatten the cloned image return ABORT error if the depth is
    greater than soft limit add a task to flatten the image and return success
```

* Delete snapshot or pvc

* Move the temporary cloned image to the trash
* Add task to remove the image from the trash

```bash
1) rbd trash mv <cloned image>
2) ceph rbd task trash remove <cloned image>
```

With earlier implementation to delete the image, we used to add
a task to remove the image with new changes this cannot be done
as the image may contain snapshots or linking.so we will be
doing below steps to delete an image(this will be
applicable for both normal image and cloned image)

* Move the rbd image to the trash
* Add task to remove the image from the trash

```bash
1) rbd trash mv <image>
2) ceph rbd task trash remove <image>
```

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

internal/rbd/controllerserver.go

@@ -18,11 +18,12 @@ package rbd
 
 import (
 	"context"
-	"fmt"
 
 	csicommon "github.com/ceph/ceph-csi/internal/csi-common"
+	"github.com/ceph/ceph-csi/internal/journal"
 	"github.com/ceph/ceph-csi/internal/util"
 
+	librbd "github.com/ceph/go-ceph/rbd"
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/kubernetes-csi/csi-lib-utils/protosanitizer"
 	"google.golang.org/grpc/codes"
@@ -178,7 +179,6 @@ func (cs *ControllerServer) CreateVolume(ctx context.Context, req *csi.CreateVol
 		return nil, err
 	}
 	defer rbdVol.Destroy()
-
 	// Existence and conflict checks
 	if acquired := cs.VolumeLocks.TryAcquire(req.GetName()); !acquired {
 		klog.Errorf(util.Log(ctx, util.VolumeOperationAlreadyExistsFmt), req.GetName())
@@ -192,22 +192,28 @@ func (cs *ControllerServer) CreateVolume(ctx context.Context, req *csi.CreateVol
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 
+	rbdSnap, err := cs.checkSnapshotSource(ctx, req, cr)
+	if err != nil {
+		return nil, err
+	}
+
 	found, err := rbdVol.Exists(ctx)
 	if err != nil {
 		if _, ok := err.(ErrVolNameConflict); ok {
 			return nil, status.Error(codes.AlreadyExists, err.Error())
 		}
-
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 	if found {
-		return buildCreateVolumeResponse(ctx, req, rbdVol)
+		if rbdSnap != nil {
-	}
+			// check if image depth is reached limit and requires flatten
-
+			err = checkFlatten(ctx, rbdVol, cr)
-	rbdSnap, err := cs.checkSnapshotSource(ctx, req, cr)
 			if err != nil {
 				return nil, err
 			}
+		}
+		return buildCreateVolumeResponse(ctx, req, rbdVol)
+	}
 
 	err = reserveVol(ctx, rbdVol, rbdSnap, cr)
 	if err != nil {
@@ -215,31 +221,22 @@ func (cs *ControllerServer) CreateVolume(ctx context.Context, req *csi.CreateVol
 	}
 	defer func() {
 		if err != nil {
+			if _, ok := err.(ErrFlattenInProgress); !ok {
 				errDefer := undoVolReservation(ctx, rbdVol, cr)
 				if errDefer != nil {
 					klog.Warningf(util.Log(ctx, "failed undoing reservation of volume: %s (%s)"), req.GetName(), errDefer)
 				}
 			}
+		}
 	}()
 
-	err = createBackingImage(ctx, cr, rbdVol, rbdSnap)
+	err = cs.createBackingImage(ctx, cr, rbdVol, rbdSnap)
 	if err != nil {
-		return nil, err
+		if _, ok := err.(ErrFlattenInProgress); ok {
-	}
+			return nil, status.Error(codes.Aborted, err.Error())
-
-	if rbdVol.Encrypted {
-		err = rbdVol.ensureEncryptionMetadataSet(rbdImageRequiresEncryption)
-		if err != nil {
-			klog.Errorf(util.Log(ctx, "failed to save encryption status, deleting image %s: %s"),
-				rbdVol, err)
-			if deleteErr := deleteImage(ctx, rbdVol, cr); deleteErr != nil {
-				klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s with error: %v"),
-					rbdVol, deleteErr)
-				return nil, deleteErr
 		}
 		return nil, err
 	}
-	}
 
 	volumeContext := req.GetParameters()
 	volumeContext["pool"] = rbdVol.Pool
@@ -262,27 +259,121 @@ func (cs *ControllerServer) CreateVolume(ctx context.Context, req *csi.CreateVol
 	return &csi.CreateVolumeResponse{Volume: volume}, nil
 }
 
-func createBackingImage(ctx context.Context, cr *util.Credentials, rbdVol *rbdVolume, rbdSnap *rbdSnapshot) error {
+// checkFlatten ensures that that the image chain depth is not reached
-	var err error
+// hardlimit or softlimit. if the softlimit is reached it adds a task and
-
+// return success,the hardlimit is reached it starts a task to flatten the
-	if rbdSnap != nil {
+// image and return Aborted
-		err = restoreSnapshot(ctx, rbdVol, rbdSnap, cr)
+func checkFlatten(ctx context.Context, rbdVol *rbdVolume, cr *util.Credentials) error {
+	err := rbdVol.flattenRbdImage(ctx, cr, false)
 	if err != nil {
+		if _, ok := err.(ErrFlattenInProgress); ok {
+			return status.Error(codes.Aborted, err.Error())
+		}
+		if errDefer := deleteImage(ctx, rbdVol, cr); errDefer != nil {
+			klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s with error: %v"), rbdVol, errDefer)
+			return status.Error(codes.Internal, err.Error())
+		}
+		errDefer := undoVolReservation(ctx, rbdVol, cr)
+		if errDefer != nil {
+			klog.Warningf(util.Log(ctx, "failed undoing reservation of volume: %s (%s)"), rbdVol.RequestName, errDefer)
+		}
+		return status.Error(codes.Internal, err.Error())
+	}
+	return nil
+}
+
+func (cs *ControllerServer) createVolumeFromSnapshot(ctx context.Context, cr *util.Credentials, rbdVol *rbdVolume, snapshotID string) error {
+	rbdSnap := &rbdSnapshot{}
+	if acquired := cs.SnapshotLocks.TryAcquire(snapshotID); !acquired {
+		klog.Infof(util.Log(ctx, util.SnapshotOperationAlreadyExistsFmt), snapshotID)
+		return status.Errorf(codes.Aborted, util.VolumeOperationAlreadyExistsFmt, snapshotID)
+	}
+	defer cs.SnapshotLocks.Release(snapshotID)
+
+	err := genSnapFromSnapID(ctx, rbdSnap, snapshotID, cr)
+	if err != nil {
+		if _, ok := err.(util.ErrPoolNotFound); ok {
+			klog.Errorf(util.Log(ctx, "failed to get backend snapshot for %s: %v"), snapshotID, err)
+			return status.Error(codes.InvalidArgument, err.Error())
+		}
+		return status.Error(codes.Internal, err.Error())
+	}
+
+	// update parent name(rbd image name in snapshot)
+	rbdSnap.RbdImageName = rbdSnap.RbdSnapName
+	// create clone image and delete snapshot
+	err = rbdVol.cloneRbdImageFromSnapshot(ctx, rbdSnap)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to clone rbd image %s from snapshot %s: %v"), rbdSnap, err)
 		return err
 	}
 
-		klog.V(4).Infof(util.Log(ctx, "created volume %s from snapshot %s"), rbdVol.RequestName, rbdSnap.RbdSnapName)
+	klog.V(4).Infof(util.Log(ctx, "create volume %s from snapshot %s"), rbdVol.RequestName, rbdSnap.RbdSnapName)
 	return nil
-	}
+}
 
+func (cs *ControllerServer) createBackingImage(ctx context.Context, cr *util.Credentials, rbdVol *rbdVolume, rbdSnap *rbdSnapshot) error {
+	var err error
+
+	var j = &journal.Connection{}
+	j, err = volJournal.Connect(rbdVol.Monitors, cr)
+	if err != nil {
+		return status.Error(codes.Internal, err.Error())
+	}
+	defer j.Destroy()
+
+	if rbdSnap != nil {
+		err = cs.createVolumeFromSnapshot(ctx, cr, rbdVol, rbdSnap.SnapID)
+		if err != nil {
+			return err
+		}
+		klog.V(4).Infof(util.Log(ctx, "created volume %s from snapshot %s"), rbdVol.RequestName, rbdSnap.RbdSnapName)
+	} else {
 		err = createImage(ctx, rbdVol, cr)
 		if err != nil {
 			klog.Errorf(util.Log(ctx, "failed to create volume: %v"), err)
 			return status.Error(codes.Internal, err.Error())
 		}
+	}
 
 	klog.V(4).Infof(util.Log(ctx, "created volume %s backed by image %s"), rbdVol.RequestName, rbdVol.RbdImageName)
 
+	defer func() {
+		if err != nil {
+			if _, ok := err.(ErrFlattenInProgress); !ok {
+				if deleteErr := deleteImage(ctx, rbdVol, cr); deleteErr != nil {
+					klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s with error: %v"), rbdVol, deleteErr)
+				}
+			}
+		}
+	}()
+	err = rbdVol.getImageID()
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to get volume id %s: %v"), rbdVol, err)
+		return status.Error(codes.Internal, err.Error())
+	}
+
+	err = j.StoreImageID(ctx, rbdVol.JournalPool, rbdVol.ReservedID, rbdVol.ImageID, cr)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to reserve volume %s: %v"), rbdVol, err)
+		return status.Error(codes.Internal, err.Error())
+	}
+
+	if rbdSnap != nil {
+		err = rbdVol.flattenRbdImage(ctx, cr, false)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to flatten image %s: %v"), rbdVol, err)
+			return err
+		}
+	}
+	if rbdVol.Encrypted {
+		err = rbdVol.ensureEncryptionMetadataSet(rbdImageRequiresEncryption)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to save encryption status, deleting image %s: %s"),
+				rbdVol, err)
+			return status.Error(codes.Internal, err.Error())
+		}
+	}
 	return nil
 }
 
@@ -315,7 +406,6 @@ func (cs *ControllerServer) checkSnapshotSource(ctx context.Context, req *csi.Cr
 
 		return nil, status.Error(codes.InvalidArgument, "missing requested Snapshot ID")
 	}
-
 	return rbdSnap, nil
 }
 
@@ -335,7 +425,6 @@ func (cs *ControllerServer) DeleteLegacyVolume(ctx context.Context, req *csi.Del
 	defer cs.VolumeLocks.Release(volumeID)
 
 	rbdVol := &rbdVolume{}
-	defer rbdVol.Destroy()
 	if err := cs.MetadataStore.Get(volumeID, rbdVol); err != nil {
 		if err, ok := err.(*util.CacheEntryNotFound); ok {
 			klog.Warningf(util.Log(ctx, "metadata for legacy volume %s not found, assuming the volume to be already deleted (%v)"), volumeID, err)
@@ -350,6 +439,13 @@ func (cs *ControllerServer) DeleteLegacyVolume(ctx context.Context, req *csi.Del
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 
+	defer rbdVol.Destroy()
+
+	err := rbdVol.Connect(cr)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+
 	// Update rbdImageName as the VolName when dealing with version 1 volumes
 	rbdVol.RbdImageName = rbdVol.VolName
 
@@ -393,7 +489,10 @@ func (cs *ControllerServer) DeleteVolume(ctx context.Context, req *csi.DeleteVol
 	}
 	defer cs.VolumeLocks.Release(volumeID)
 
-	rbdVol, err := genVolFromVolID(ctx, volumeID, cr, req.GetSecrets())
+	rbdVol := &rbdVolume{}
+	defer rbdVol.Destroy()
+
+	rbdVol, err = genVolFromVolID(ctx, volumeID, cr, req.GetSecrets())
 	if err != nil {
 		switch err.(type) {
 		case util.ErrPoolNotFound:
@@ -420,7 +519,6 @@ func (cs *ControllerServer) DeleteVolume(ctx context.Context, req *csi.DeleteVol
 
 		// All errors other than ErrImageNotFound should return an error back to the caller
 		case ErrImageNotFound:
-			break
 		default:
 			return nil, status.Error(codes.Internal, err.Error())
 		}
@@ -509,8 +607,10 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 	}
 	defer cr.DeleteCredentials()
 
+	rbdVol := &rbdVolume{}
+	defer rbdVol.Destroy()
 	// Fetch source volume information
-	rbdVol, err := genVolFromVolID(ctx, req.GetSourceVolumeId(), cr, req.GetSecrets())
+	rbdVol, err = genVolFromVolID(ctx, req.GetSourceVolumeId(), cr, req.GetSecrets())
 	if err != nil {
 		switch err.(type) {
 		case ErrImageNotFound:
@@ -536,7 +636,6 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 		return nil, status.Errorf(codes.InvalidArgument, "volume(%s) has not snapshot feature(layering)", req.GetSourceVolumeId())
 	}
 
-	// Create snap volume
 	rbdSnap := genSnapFromOptions(ctx, rbdVol, req.GetParameters())
 	rbdSnap.RbdImageName = rbdVol.RbdImageName
 	rbdSnap.SizeBytes = rbdVol.VolSize
@@ -551,15 +650,45 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 
 	// Need to check for already existing snapshot name, and if found
 	// check for the requested source volume id and already allocated source volume id
-	found, err := checkSnapExists(ctx, rbdSnap, cr)
+	found, err := checkSnapCloneExists(ctx, rbdVol, rbdSnap, cr)
 	if err != nil {
 		if _, ok := err.(util.ErrSnapNameConflict); ok {
 			return nil, status.Error(codes.AlreadyExists, err.Error())
 		}
-
 		return nil, status.Errorf(codes.Internal, err.Error())
 	}
 	if found {
+		vol := generateVolFromSnap(rbdSnap)
+		err = vol.Connect(cr)
+		if err != nil {
+			uErr := undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+			if uErr != nil {
+				klog.Warningf(util.Log(ctx, "failed undoing reservation of snapshot: %s %v"), req.GetName(), uErr)
+			}
+			return nil, status.Errorf(codes.Internal, err.Error())
+		}
+		defer vol.Destroy()
+
+		err = vol.flattenRbdImage(ctx, cr, false)
+		if _, ok := err.(ErrFlattenInProgress); ok {
+			return &csi.CreateSnapshotResponse{
+				Snapshot: &csi.Snapshot{
+					SizeBytes:      rbdSnap.SizeBytes,
+					SnapshotId:     rbdSnap.SnapID,
+					SourceVolumeId: rbdSnap.SourceVolumeID,
+					CreationTime:   rbdSnap.CreatedAt,
+					ReadyToUse:     false,
+				},
+			}, nil
+		}
+		if err != nil {
+			uErr := undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+			if uErr != nil {
+				klog.Warningf(util.Log(ctx, "failed undoing reservation of snapshot: %s %v"), req.GetName(), uErr)
+			}
+			return nil, status.Errorf(codes.Internal, err.Error())
+		}
+
 		return &csi.CreateSnapshotResponse{
 			Snapshot: &csi.Snapshot{
 				SizeBytes:      rbdSnap.SizeBytes,
@@ -571,7 +700,7 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 		}, nil
 	}
 
-	err = reserveSnap(ctx, rbdSnap, cr)
+	err = reserveSnap(ctx, rbdSnap, rbdVol, cr)
 	if err != nil {
 		return nil, status.Error(codes.Internal, err.Error())
 	}
@@ -584,18 +713,21 @@ func (cs *ControllerServer) CreateSnapshot(ctx context.Context, req *csi.CreateS
 		}
 	}()
 
-	err = cs.doSnapshot(ctx, rbdSnap, cr)
+	ready := false
+	var vol = new(rbdVolume)
+
+	ready, vol, err = cs.doSnapshotClone(ctx, rbdVol, rbdSnap, cr)
 	if err != nil {
 		return nil, err
 	}
 
 	return &csi.CreateSnapshotResponse{
 		Snapshot: &csi.Snapshot{
-			SizeBytes:      rbdSnap.SizeBytes,
+			SizeBytes:      vol.VolSize,
-			SnapshotId:     rbdSnap.SnapID,
+			SnapshotId:     vol.VolID,
 			SourceVolumeId: req.GetSourceVolumeId(),
-			CreationTime:   rbdSnap.CreatedAt,
+			CreationTime:   vol.CreatedAt,
-			ReadyToUse:     true,
+			ReadyToUse:     ready,
 		},
 	}, nil
 }
@@ -622,26 +754,75 @@ func (cs *ControllerServer) validateSnapshotReq(ctx context.Context, req *csi.Cr
 	return nil
 }
 
-func (cs *ControllerServer) doSnapshot(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credentials) (err error) {
+func (cs *ControllerServer) doSnapshotClone(ctx context.Context, parentVol *rbdVolume, rbdSnap *rbdSnapshot, cr *util.Credentials) (bool, *rbdVolume, error) {
-	err = createSnapshot(ctx, rbdSnap, cr)
+	// generate cloned volume details from snapshot
-	// If snap creation fails, even due to snapname already used, fail, next attempt will get a new
+	cloneRbd := generateVolFromSnap(rbdSnap)
-	// uuid for use as the snap name
+	defer cloneRbd.Destroy()
+	// add image feature for cloneRbd
+	f := []string{librbd.FeatureNameLayering, librbd.FeatureNameDeepFlatten}
+	cloneRbd.imageFeatureSet = librbd.FeatureSetFromNames(f)
+	ready := false
+
+	err := cloneRbd.Connect(cr)
+	if err != nil {
+		return ready, cloneRbd, err
+	}
+
+	err = createRBDClone(ctx, parentVol, cloneRbd, rbdSnap, cr)
 	if err != nil {
 		klog.Errorf(util.Log(ctx, "failed to create snapshot: %v"), err)
-		return status.Error(codes.Internal, err.Error())
+		return ready, cloneRbd, status.Error(codes.Internal, err.Error())
 	}
+
 	defer func() {
 		if err != nil {
-			errDefer := deleteSnapshot(ctx, rbdSnap, cr)
+			if _, ok := err.(ErrFlattenInProgress); !ok {
-			if errDefer != nil {
+				// cleanup clone and snapshot
-				klog.Errorf(util.Log(ctx, "failed to delete snapshot: %v"), errDefer)
+				errCleanUp := cleanUpSnapshot(ctx, cloneRbd, rbdSnap, cloneRbd, cr)
-				err = fmt.Errorf("snapshot created but failed to delete snapshot due to"+
+				if errCleanUp != nil {
-					" other failures: %v", err)
+					klog.Errorf(util.Log(ctx, "failed to cleanup snapshot and clone: %v"), errCleanUp)
+				}
 			}
-			err = status.Error(codes.Internal, err.Error())
 		}
 	}()
-	return err
+
+	err = cloneRbd.createSnapshot(ctx, rbdSnap)
+	if err != nil {
+		// update rbd image name for logging
+		rbdSnap.RbdImageName = cloneRbd.RbdImageName
+		klog.Errorf(util.Log(ctx, "failed to create snapshot %s: %v"), rbdSnap, err)
+		return ready, cloneRbd, err
+	}
+
+	err = cloneRbd.getImageID()
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to get image id: %v"), err)
+		return ready, cloneRbd, err
+	}
+	var j = &journal.Connection{}
+	// save image ID
+	j, err = snapJournal.Connect(rbdSnap.Monitors, cr)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to connect to cluster: %v"), err)
+		return ready, cloneRbd, err
+	}
+	defer j.Destroy()
+
+	err = j.StoreImageID(ctx, rbdSnap.JournalPool, rbdSnap.ReservedID, cloneRbd.ImageID, cr)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to reserve volume id: %v"), err)
+		return ready, cloneRbd, err
+	}
+
+	err = cloneRbd.flattenRbdImage(ctx, cr, false)
+	if err != nil {
+		if _, ok := err.(ErrFlattenInProgress); ok {
+			return ready, cloneRbd, nil
+		}
+		return ready, cloneRbd, err
+	}
+	ready = true
+	return ready, cloneRbd, nil
 }
 
 // DeleteSnapshot deletes the snapshot in backend and removes the
@@ -685,26 +866,9 @@ func (cs *ControllerServer) DeleteSnapshot(ctx context.Context, req *csi.DeleteS
 			return &csi.DeleteSnapshotResponse{}, nil
 		}
 
-		// All errors other than ErrSnapNotFound should return an error back to the caller
-		if _, ok := err.(ErrSnapNotFound); !ok {
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 
-		// Consider missing snap as already deleted, and proceed to remove the omap values,
-		// safeguarding against parallel create or delete requests against the
-		// same name.
-		if acquired := cs.SnapshotLocks.TryAcquire(rbdSnap.RequestName); !acquired {
-			klog.Errorf(util.Log(ctx, util.SnapshotOperationAlreadyExistsFmt), rbdSnap.RequestName)
-			return nil, status.Errorf(codes.Aborted, util.VolumeOperationAlreadyExistsFmt, rbdSnap.RequestName)
-		}
-		defer cs.SnapshotLocks.Release(rbdSnap.RequestName)
-
-		if err = undoSnapReservation(ctx, rbdSnap, cr); err != nil {
-			return nil, status.Error(codes.Internal, err.Error())
-		}
-		return &csi.DeleteSnapshotResponse{}, nil
-	}
-
 	// safeguard against parallel create or delete requests against the same
 	// name
 	if acquired := cs.SnapshotLocks.TryAcquire(rbdSnap.RequestName); !acquired {
@@ -713,11 +877,52 @@ func (cs *ControllerServer) DeleteSnapshot(ctx context.Context, req *csi.DeleteS
 	}
 	defer cs.SnapshotLocks.Release(rbdSnap.RequestName)
 
-	// Deleting snapshot
+	// Deleting snapshot and cloned volume
-	klog.V(4).Infof(util.Log(ctx, "deleting Snaphot %s"), rbdSnap)
+	klog.V(4).Infof(util.Log(ctx, "deleting cloned rbd volume %s"), rbdSnap.RbdSnapName)
-	if err := deleteSnapshot(ctx, rbdSnap, cr); err != nil {
+
-		return nil, status.Errorf(codes.FailedPrecondition,
+	rbdVol := generateVolFromSnap(rbdSnap)
-			"failed to delete snapshot: %s with error: %v", rbdSnap, err)
+
+	err = rbdVol.Connect(cr)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	defer rbdVol.Destroy()
+
+	err = rbdVol.getImageInfo()
+	if err != nil {
+		if _, ok := err.(ErrImageNotFound); !ok {
+			klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s/%s with error: %v"), rbdVol.Pool, rbdVol.VolName, err)
+			return nil, status.Error(codes.Internal, err.Error())
+		}
+	} else {
+		// save image ID
+		var j = &journal.Connection{}
+		j, err = snapJournal.Connect(rbdSnap.Monitors, cr)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to connect to cluster: %v"), err)
+			return nil, status.Error(codes.Internal, err.Error())
+		}
+		defer j.Destroy()
+		// TODO replace GetStoredImageID with GetImageAttributes in all places
+		rbdVol.ImageID, err = j.GetStoredImageID(ctx, rbdSnap.JournalPool, rbdSnap.ReservedID, cr)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to get reserved image id: %v"), err)
+			return nil, status.Error(codes.Internal, err.Error())
+		}
+		// update parent name to delete the snapshot
+		rbdSnap.RbdImageName = rbdVol.RbdImageName
+
+		err = cleanUpSnapshot(ctx, rbdVol, rbdSnap, rbdVol, cr)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to delete image: %v"), err)
+			return nil, status.Error(codes.Internal, err.Error())
+		}
+	}
+	err = undoSnapReservation(ctx, rbdSnap, cr)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to remove reservation for snapname (%s) with backing snap (%s) on image (%s) (%s)"),
+			rbdSnap.RequestName, rbdSnap.RbdSnapName, rbdSnap.RbdImageName, err)
+		return nil, status.Error(codes.Internal, err.Error())
 	}
 
 	return &csi.DeleteSnapshotResponse{}, nil
@@ -753,7 +958,10 @@ func (cs *ControllerServer) ControllerExpandVolume(ctx context.Context, req *csi
 	}
 	defer cr.DeleteCredentials()
 
-	rbdVol, err := genVolFromVolID(ctx, volID, cr, req.GetSecrets())
+	rbdVol := &rbdVolume{}
+	defer rbdVol.Destroy()
+
+	rbdVol, err = genVolFromVolID(ctx, volID, cr, req.GetSecrets())
 	if err != nil {
 		switch err.(type) {
 		case ErrImageNotFound:

internal/rbd/errors.go

@@ -66,3 +66,12 @@ type ErrMissingStash struct {
 func (e ErrMissingStash) Error() string {
 	return e.err.Error()
 }
+
+// ErrFlattenInProgress is returned when flatten is inprogess for an image
+type ErrFlattenInProgress struct {
+	err error
+}
+
+func (e ErrFlattenInProgress) Error() string {
+	return e.err.Error()
+}

internal/rbd/rbd_journal.go

@@ -87,28 +87,31 @@ func validateRbdVol(rbdVol *rbdVolume) error {
 }
 
 /*
-checkSnapExists, and its counterpart checkVolExists, function checks if the passed in rbdSnapshot
+checkSnapCloneExists, and its counterpart checkVolExists, function checks if
-or rbdVolume exists on the backend.
+the passed in rbdSnapshot or rbdVolume exists on the backend.
 
-**NOTE:** These functions manipulate the rados omaps that hold information regarding
+**NOTE:** These functions manipulate the rados omaps that hold information
-volume names as requested by the CSI drivers. Hence, these need to be invoked only when the
+regarding volume names as requested by the CSI drivers. Hence, these need to be
-respective CSI driver generated snapshot or volume name based locks are held, as otherwise racy
+invoked only when the respective CSI driver generated snapshot or volume name
-access to these omaps may end up leaving them in an inconsistent state.
+based locks are held, as otherwise racy access to these omaps may end up
+leaving them in an inconsistent state.
 
-These functions need enough information about cluster and pool (ie, Monitors, Pool, IDs filled in)
+These functions need enough information about cluster and pool (ie, Monitors,
-to operate. They further require that the RequestName element of the structure have a valid value
+Pool, IDs filled in) to operate. They further require that the RequestName
-to operate on and determine if the said RequestName already exists on the backend.
+element of the structure have a valid value to operate on and determine if the
+said RequestName already exists on the backend.
 
-These functions populate the snapshot or the image name, its attributes and the CSI snapshot/volume
+These functions populate the snapshot or the image name, its attributes and the
-ID for the same when successful.
+CSI snapshot/volume ID for the same when successful.
 
-These functions also cleanup omap reservations that are stale. I.e when omap entries exist and
+These functions also cleanup omap reservations that are stale. I.e when omap
-backing images or snapshots are missing, or one of the omaps exist and the next is missing. This is
+entries exist and backing images or snapshots are missing, or one of the omaps
-because, the order of omap creation and deletion are inverse of each other, and protected by the
+exist and the next is missing. This is because, the order of omap creation and
-request name lock, and hence any stale omaps are leftovers from incomplete transactions and are
+deletion are inverse of each other, and protected by the request name lock, and
-hence safe to garbage collect.
+hence any stale omaps are leftovers from incomplete transactions and are hence
+safe to garbage collect.
 */
-func checkSnapExists(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credentials) (bool, error) {
+func checkSnapCloneExists(ctx context.Context, parentVol *rbdVolume, rbdSnap *rbdSnapshot, cr *util.Credentials) (bool, error) {
 	err := validateRbdSnap(rbdSnap)
 	if err != nil {
 		return false, err
@@ -137,6 +140,36 @@ func checkSnapExists(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credent
 			snapData.ImagePool, rbdSnap.Pool)
 	}
 
+	vol := generateVolFromSnap(rbdSnap)
+	defer vol.Destroy()
+	err = vol.Connect(cr)
+	if err != nil {
+		return false, err
+	}
+	vol.ReservedID = snapUUID
+	// Fetch on-disk image attributes
+	err = vol.getImageInfo()
+	if err != nil {
+		if _, ok := err.(ErrImageNotFound); ok {
+			err = parentVol.deleteSnapshot(ctx, rbdSnap)
+			if err != nil {
+				if _, ok := err.(ErrSnapNotFound); !ok {
+					klog.Errorf(util.Log(ctx, "failed to delete snapshot %s: %v"), rbdSnap, err)
+					return false, err
+				}
+			}
+			err = undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+		}
+		return false, err
+	}
+
+	// Snapshot creation transaction is rolled forward if rbd clone image
+	// representing the snapshot is found. Any failures till finding the image
+	// causes a roll back of the snapshot creation transaction.
+	// Code from here on, rolls the transaction forward.
+
+	rbdSnap.CreatedAt = vol.CreatedAt
+	rbdSnap.SizeBytes = vol.VolSize
 	// found a snapshot already available, process and return its information
 	rbdSnap.SnapID, err = util.GenerateVolID(ctx, rbdSnap.Monitors, cr, snapData.ImagePoolID, rbdSnap.Pool,
 		rbdSnap.ClusterID, snapUUID, volIDVersion)
@@ -144,9 +177,43 @@ func checkSnapExists(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credent
 		return false, err
 	}
 
-	klog.V(4).Infof(util.Log(ctx, "found existing snap (%s) with snap name (%s) for request (%s)"),
+	// check snapshot exists if not create it
-		rbdSnap.SnapID, rbdSnap.RbdSnapName, rbdSnap.RequestName)
+	_, err = vol.getSnapInfo(rbdSnap)
+	if _, ok := err.(ErrSnapNotFound); ok {
+		// create snapshot
+		sErr := vol.createSnapshot(ctx, rbdSnap)
+		if sErr != nil {
+			klog.Errorf(util.Log(ctx, "failed to create snapshot %s: %v"), rbdSnap, sErr)
+			err = undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+			return false, err
+		}
+	}
+	if err != nil {
+		return false, err
+	}
 
+	vol.ImageID, err = j.GetStoredImageID(ctx, vol.JournalPool, vol.ReservedID, cr)
+	if _, ok := err.(util.ErrKeyNotFound); ok {
+		sErr := vol.getImageID()
+		if sErr != nil {
+			klog.Errorf(util.Log(ctx, "failed to get image id %s: %v"), vol, sErr)
+			err = undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+			return false, err
+		}
+		sErr = j.StoreImageID(ctx, vol.JournalPool, vol.ReservedID, vol.ImageID, cr)
+		if sErr != nil {
+			klog.Errorf(util.Log(ctx, "failed to store volume id %s: %v"), vol, sErr)
+			err = undoSnapshotCloning(ctx, vol, rbdSnap, vol, cr)
+			return false, err
+		}
+	}
+
+	if err != nil {
+		return false, err
+	}
+
+	klog.V(4).Infof(util.Log(ctx, "found existing image (%s) with name (%s) for request (%s)"),
+		rbdSnap.SnapID, rbdSnap.RbdSnapName, rbdSnap.RequestName)
 	return true, nil
 }
 
@@ -184,7 +251,7 @@ func (rv *rbdVolume) Exists(ctx context.Context) (bool, error) {
 		return false, nil
 	}
 
-	imageUUID := imageData.ImageUUID
+	rv.ReservedID = imageData.ImageUUID
 	rv.RbdImageName = imageData.ImageAttributes.ImageName
 
 	// check if topology constraints match what is found
@@ -223,7 +290,7 @@ func (rv *rbdVolume) Exists(ctx context.Context) (bool, error) {
 
 	// found a volume already available, process and return it!
 	rv.VolID, err = util.GenerateVolID(ctx, rv.Monitors, rv.conn.Creds, imageData.ImagePoolID, rv.Pool,
-		rv.ClusterID, imageUUID, volIDVersion)
+		rv.ClusterID, rv.ReservedID, volIDVersion)
 	if err != nil {
 		return false, err
 	}
@@ -236,9 +303,8 @@ func (rv *rbdVolume) Exists(ctx context.Context) (bool, error) {
 
 // reserveSnap is a helper routine to request a rbdSnapshot name reservation and generate the
 // volume ID for the generated name
-func reserveSnap(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credentials) error {
+func reserveSnap(ctx context.Context, rbdSnap *rbdSnapshot, rbdVol *rbdVolume, cr *util.Credentials) error {
 	var (
-		snapUUID string
 		err error
 	)
 
@@ -253,15 +319,15 @@ func reserveSnap(ctx context.Context, rbdSnap *rbdSnapshot, cr *util.Credentials
 	}
 	defer j.Destroy()
 
-	snapUUID, rbdSnap.RbdSnapName, err = j.ReserveName(
+	rbdSnap.ReservedID, rbdSnap.RbdSnapName, err = j.ReserveName(
 		ctx, rbdSnap.JournalPool, journalPoolID, rbdSnap.Pool, imagePoolID,
-		rbdSnap.RequestName, rbdSnap.NamePrefix, rbdSnap.RbdImageName, "")
+		rbdSnap.RequestName, rbdSnap.NamePrefix, rbdVol.RbdImageName, "")
 	if err != nil {
 		return err
 	}
 
 	rbdSnap.SnapID, err = util.GenerateVolID(ctx, rbdSnap.Monitors, cr, imagePoolID, rbdSnap.Pool,
-		rbdSnap.ClusterID, snapUUID, volIDVersion)
+		rbdSnap.ClusterID, rbdSnap.ReservedID, volIDVersion)
 	if err != nil {
 		return err
 	}
@@ -307,7 +373,6 @@ func updateTopologyConstraints(rbdVol *rbdVolume, rbdSnap *rbdSnapshot) error {
 // volume ID for the generated name
 func reserveVol(ctx context.Context, rbdVol *rbdVolume, rbdSnap *rbdSnapshot, cr *util.Credentials) error {
 	var (
-		imageUUID string
 		err error
 	)
 
@@ -332,7 +397,7 @@ func reserveVol(ctx context.Context, rbdVol *rbdVolume, rbdSnap *rbdSnapshot, cr
 	}
 	defer j.Destroy()
 
-	imageUUID, rbdVol.RbdImageName, err = j.ReserveName(
+	rbdVol.ReservedID, rbdVol.RbdImageName, err = j.ReserveName(
 		ctx, rbdVol.JournalPool, journalPoolID, rbdVol.Pool, imagePoolID,
 		rbdVol.RequestName, rbdVol.NamePrefix, "", kmsID)
 	if err != nil {
@@ -340,7 +405,7 @@ func reserveVol(ctx context.Context, rbdVol *rbdVolume, rbdSnap *rbdSnapshot, cr
 	}
 
 	rbdVol.VolID, err = util.GenerateVolID(ctx, rbdVol.Monitors, cr, imagePoolID, rbdVol.Pool,
-		rbdVol.ClusterID, imageUUID, volIDVersion)
+		rbdVol.ClusterID, rbdVol.ReservedID, volIDVersion)
 	if err != nil {
 		return err
 	}

internal/rbd/rbd_util.go

@@ -33,6 +33,7 @@ import (
 	"github.com/ceph/go-ceph/rados"
 	librbd "github.com/ceph/go-ceph/rbd"
 	"github.com/container-storage-interface/spec/lib/go/csi"
+	"github.com/golang/protobuf/ptypes"
 	"github.com/golang/protobuf/ptypes/timestamp"
 	"github.com/pborman/uuid"
 	"github.com/pkg/errors"
@@ -62,6 +63,9 @@ const (
 	rbdImageRequiresEncryption = "requiresEncryption"
 	// image metadata key for encryption
 	encryptionMetaKey = ".rbd.csi.ceph.com/encrypted"
+
+	// go-ceph will provide rbd.ImageOptionCloneFormat
+	imageOptionCloneFormat = librbd.RbdImageOption(12)
 )
 
 // rbdVolume represents a CSI volume and its RBD image specifics
@@ -89,6 +93,7 @@ type rbdVolume struct {
 	Pool                string `json:"pool"`
 	DataPool            string
 	ImageID             string
+	ParentName          string
 	imageFeatureSet     librbd.FeatureSet
 	AdminID             string `json:"adminId"`
 	UserID              string `json:"userId"`
@@ -103,7 +108,7 @@ type rbdVolume struct {
 	Encrypted           bool
 	readOnly            bool
 	KMS                 util.EncryptionKMS
-
+	CreatedAt           *timestamp.Timestamp
 	// conn is a connection to the Ceph cluster obtained from a ConnPool
 	conn *util.ClusterConnection
 	// an opened IOContext, call .openIoctx() before using
@@ -391,24 +396,113 @@ func deleteImage(ctx context.Context, pOpts *rbdVolume, cr *util.Credentials) er
 	return nil
 }
 
-func (rv *rbdVolume) removeImageFromTrash() error {
+func (rv *rbdVolume) getCloneDepth(ctx context.Context) (uint, error) {
-	err := rv.openIoctx()
+	var depth uint
+	vol := rbdVolume{
+		Pool:         rv.Pool,
+		Monitors:     rv.Monitors,
+		RbdImageName: rv.RbdImageName,
+		conn:         rv.conn,
+	}
+
+	err := vol.openIoctx()
+	if err != nil {
+		return depth, err
+	}
+
+	defer func() {
+		vol.ioctx.Destroy()
+	}()
+	for {
+		if vol.RbdImageName == "" {
+			return depth, nil
+		}
+		err = vol.getImageInfo()
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to check depth on image %s: %s"), vol, err)
+			return depth, err
+		}
+		if vol.ParentName != "" {
+			depth++
+		}
+		vol.RbdImageName = vol.ParentName
+	}
+}
+
+func (rv *rbdVolume) flattenRbdImage(ctx context.Context, cr *util.Credentials, forceFlatten bool) error {
+	depth, err := rv.getCloneDepth(ctx)
 	if err != nil {
 		return err
 	}
-	list, err := librbd.GetTrashList(rv.ioctx)
+	klog.Infof(util.Log(ctx, "clone depth is (%d), configured softlimit (%d) and hardlimit (%d) for %s"), depth, rbdSoftMaxCloneDepth, rbdHardMaxCloneDepth, rv)
+
+	if forceFlatten || (depth >= rbdHardMaxCloneDepth) || (depth >= rbdSoftMaxCloneDepth) {
+		args := []string{"flatten", rv.Pool + "/" + rv.RbdImageName, "--id", cr.ID, "--keyfile=" + cr.KeyFile, "-m", rv.Monitors}
+		supported, err := addRbdManagerTask(ctx, rv, args)
+		if supported {
+			if err != nil {
+				klog.Errorf(util.Log(ctx, "failed to add task flatten for %s : %v"), rv, err)
+				return err
+			}
+			if forceFlatten || depth >= rbdHardMaxCloneDepth {
+				return ErrFlattenInProgress{err: fmt.Errorf("flatten is in progress for image %s", rv.RbdImageName)}
+			}
+		}
+		if !supported {
+			klog.Errorf(util.Log(ctx, "task manager does not support flatten,image will be flattened once hardlimit is reached: %v"), err)
+			if forceFlatten || depth >= rbdHardMaxCloneDepth {
+				err = rv.Connect(cr)
 				if err != nil {
 					return err
 				}
-	for _, l := range list {
+				rbdImage, err := rv.open()
-		if l.Name == rv.RbdImageName {
+				if err != nil {
-			err = librbd.TrashRemove(rv.ioctx, l.Id, true)
 					return err
 				}
+				defer rbdImage.Close()
+				if err = rbdImage.Flatten(); err != nil {
+					klog.Errorf(util.Log(ctx, "rbd failed to flatten image %s %s: %v"), rv.Pool, rv.RbdImageName, err)
+					return err
+				}
+			}
+		}
 	}
 	return nil
 }
 
+func (rv *rbdVolume) hasFeature(feature uint64) bool {
+	return (uint64(rv.imageFeatureSet) & feature) == feature
+}
+
+func (rv *rbdVolume) checkImageChainHasFeature(ctx context.Context, feature uint64) (bool, error) {
+	vol := rbdVolume{
+		Pool:         rv.Pool,
+		Monitors:     rv.Monitors,
+		RbdImageName: rv.RbdImageName,
+		conn:         rv.conn,
+	}
+	err := vol.openIoctx()
+	if err != nil {
+		return false, err
+	}
+	defer vol.ioctx.Destroy()
+
+	for {
+		if vol.RbdImageName == "" {
+			return false, nil
+		}
+		err = vol.getImageInfo()
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to get image info for %s: %s"), vol, err)
+			return false, err
+		}
+		if f := vol.hasFeature(feature); f {
+			return true, nil
+		}
+		vol.RbdImageName = vol.ParentName
+	}
+}
+
 // genSnapFromSnapID generates a rbdSnapshot structure from the provided identifier, updating
 // the structure with elements from on-disk snapshot metadata as well
 func genSnapFromSnapID(ctx context.Context, rbdSnap *rbdSnapshot, snapshotID string, cr *util.Credentials) error {
@@ -454,7 +548,7 @@ func genSnapFromSnapID(ctx context.Context, rbdSnap *rbdSnapshot, snapshotID str
 	rbdSnap.RequestName = imageAttributes.RequestName
 	rbdSnap.RbdImageName = imageAttributes.SourceName
 	rbdSnap.RbdSnapName = imageAttributes.ImageName
-
+	rbdSnap.ReservedID = vi.ObjectUUID
 	// convert the journal pool ID to name, for use in DeleteSnapshot cases
 	if imageAttributes.JournalPoolID != util.InvalidPoolID {
 		rbdSnap.JournalPool, err = util.GetPoolName(rbdSnap.Monitors, cr, imageAttributes.JournalPoolID)
@@ -484,7 +578,7 @@ func genVolFromVolID(ctx context.Context, volumeID string, cr *util.Credentials,
 	err := vi.DecomposeCSIID(rbdVol.VolID)
 	if err != nil {
 		err = fmt.Errorf("error decoding volume ID (%s) (%s)", err, rbdVol.VolID)
-		return nil, ErrInvalidVolID{err}
+		return rbdVol, ErrInvalidVolID{err}
 	}
 
 	rbdVol.ClusterID = vi.ClusterID
@@ -492,53 +586,71 @@ func genVolFromVolID(ctx context.Context, volumeID string, cr *util.Credentials,
 
 	rbdVol.Monitors, _, err = getMonsAndClusterID(ctx, options)
 	if err != nil {
-		return nil, err
+		return rbdVol, err
 	}
 
 	rbdVol.Pool, err = util.GetPoolName(rbdVol.Monitors, cr, vi.LocationID)
 	if err != nil {
-		return nil, err
+		return rbdVol, err
 	}
 
 	err = rbdVol.Connect(cr)
 	if err != nil {
-		return nil, err
+		return rbdVol, err
 	}
 	rbdVol.JournalPool = rbdVol.Pool
 
 	j, err := volJournal.Connect(rbdVol.Monitors, cr)
 	if err != nil {
-		return nil, err
+		return rbdVol, err
 	}
 	defer j.Destroy()
 
 	imageAttributes, err := j.GetImageAttributes(
 		ctx, rbdVol.Pool, vi.ObjectUUID, false)
 	if err != nil {
-		return nil, err
+		return rbdVol, err
 	}
 
+	rbdVol.RequestName = imageAttributes.RequestName
+	rbdVol.RbdImageName = imageAttributes.ImageName
+	rbdVol.ReservedID = vi.ObjectUUID
+
 	if imageAttributes.KmsID != "" {
 		rbdVol.Encrypted = true
 		rbdVol.KMS, err = util.GetKMS(imageAttributes.KmsID, secrets)
 		if err != nil {
-			return nil, err
+			return rbdVol, err
 		}
 	}
-	rbdVol.RequestName = imageAttributes.RequestName
-	rbdVol.RbdImageName = imageAttributes.ImageName
-
 	// convert the journal pool ID to name, for use in DeleteVolume cases
 	if imageAttributes.JournalPoolID >= 0 {
 		rbdVol.JournalPool, err = util.GetPoolName(rbdVol.Monitors, cr, imageAttributes.JournalPoolID)
 		if err != nil {
 			// TODO: If pool is not found we may leak the image (as DeleteVolume will return success)
-			return nil, err
+			return rbdVol, err
 		}
 	}
 
+	rbdVol.ImageID, err = j.GetStoredImageID(ctx, rbdVol.JournalPool, rbdVol.ReservedID, cr)
+	if _, ok := err.(util.ErrKeyNotFound); ok {
+		err = rbdVol.getImageID()
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to get image id %s: %v"), rbdVol, err)
+			return rbdVol, err
+		}
+		err = j.StoreImageID(ctx, rbdVol.JournalPool, rbdVol.ReservedID, rbdVol.ImageID, cr)
+		if err != nil {
+			klog.Errorf(util.Log(ctx, "failed to store volume id %s: %v"), rbdVol, err)
+			return rbdVol, err
+		}
+	}
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to get stored image id: %v"), err)
+		return rbdVol, err
+	}
+
 	err = rbdVol.getImageInfo()
-
 	return rbdVol, err
 }
 
@@ -789,6 +901,62 @@ func (rv *rbdVolume) cloneRbdImageFromSnapshot(ctx context.Context, pSnapOpts *r
 	return nil
 }
 
+// imageInfo strongly typed JSON spec for image info
+type imageInfo struct {
+	ObjectUUID string     `json:"name"`
+	Size       int64      `json:"size"`
+	Features   []string   `json:"features"`
+	CreatedAt  string     `json:"create_timestamp"`
+	Parent     parentInfo `json:"parent"`
+}
+
+// parentInfo  spec for parent volume  info
+type parentInfo struct {
+	Image    string `json:"image"`
+	Pool     string `json:"pool"`
+	Snapshot string `json:"snapshost"`
+}
+
+// updateVolWithImageInfo updates provided rbdVolume with information from on-disk data
+// regarding the same
+func (rv *rbdVolume) updateVolWithImageInfo(cr *util.Credentials) error {
+	// rbd --format=json info [image-spec | snap-spec]
+	var imgInfo imageInfo
+
+	stdout, stderr, err := util.ExecCommand("rbd",
+		"-m", rv.Monitors,
+		"--id", cr.ID,
+		"--keyfile="+cr.KeyFile,
+		"-c", util.CephConfigPath,
+		"--format="+"json",
+		"info", rv.String())
+	if err != nil {
+		klog.Errorf("failed getting information for image (%s): (%s)", rv, err)
+		if strings.Contains(string(stderr), "rbd: error opening image "+rv.RbdImageName+
+			": (2) No such file or directory") {
+			return ErrImageNotFound{rv.String(), err}
+		}
+		return err
+	}
+
+	err = json.Unmarshal(stdout, &imgInfo)
+	if err != nil {
+		klog.Errorf("failed to parse JSON output of image info (%s): (%s)", rv, err)
+		return fmt.Errorf("unmarshal failed: %+v.  raw buffer response: %s", err, string(stdout))
+	}
+
+	rv.VolSize = imgInfo.Size
+	rv.ParentName = imgInfo.Parent.Image
+
+	tm, err := time.Parse(time.ANSIC, imgInfo.CreatedAt)
+	if err != nil {
+		return err
+	}
+
+	rv.CreatedAt, err = ptypes.TimestampProto(tm)
+	return err
+}
+
 // getImageInfo queries rbd about the given image and returns its metadata, and returns
 // ErrImageNotFound if provided image is not found
 func (rv *rbdVolume) getImageInfo() error {
@@ -810,6 +978,10 @@ func (rv *rbdVolume) getImageInfo() error {
 		return err
 	}
 	rv.imageFeatureSet = librbd.FeatureSet(features)
+	err = rv.updateVolWithImageInfo(rv.conn.Creds)
+	if err != nil {
+		return err
+	}
 
 	return nil
 }

internal/rbd/snapshot.go

@@ -0,0 +1,101 @@
+/*
+Copyright 2020 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 rbd
+
+import (
+	"context"
+
+	"github.com/ceph/ceph-csi/internal/util"
+
+	"github.com/pkg/errors"
+	"k8s.io/klog"
+)
+
+func createRBDClone(ctx context.Context, parentVol, cloneRbdVol *rbdVolume, snap *rbdSnapshot, cr *util.Credentials) error {
+	// create snapshot
+	err := parentVol.createSnapshot(ctx, snap)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to create snapshot %s: %v"), snap, err)
+		return err
+	}
+
+	// create clone image and delete snapshot
+	err = cloneRbdVol.cloneRbdImageFromSnapshot(ctx, snap)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to clone rbd image %s from snapshot %s: %v"), cloneRbdVol.RbdImageName, snap.RbdSnapName, err)
+		err = errors.Errorf("failed to clone rbd image %s from snapshot %s: %v", cloneRbdVol.RbdImageName, snap.RbdSnapName, err)
+	}
+	errSnap := parentVol.deleteSnapshot(ctx, snap)
+	if errSnap != nil {
+		klog.Errorf(util.Log(ctx, "failed to delete snapshot: %v"), errSnap)
+		delErr := deleteImage(ctx, cloneRbdVol, cr)
+		if delErr != nil {
+			klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s with error: %v"), cloneRbdVol, delErr)
+		}
+		return err
+	}
+
+	err = cloneRbdVol.getImageInfo()
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to get rbd image: %s details with error: %v"), cloneRbdVol, err)
+		delErr := deleteImage(ctx, cloneRbdVol, cr)
+		if delErr != nil {
+			klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s with error: %v"), cloneRbdVol, delErr)
+		}
+		return err
+	}
+
+	return nil
+}
+
+func cleanUpSnapshot(ctx context.Context, parentVol *rbdVolume, rbdSnap *rbdSnapshot, rbdVol *rbdVolume, cr *util.Credentials) error {
+	err := parentVol.deleteSnapshot(ctx, rbdSnap)
+	if err != nil {
+		if _, ok := err.(ErrSnapNotFound); !ok {
+			klog.Errorf(util.Log(ctx, "failed to delete snapshot: %v"), err)
+			return err
+		}
+	}
+	err = deleteImage(ctx, rbdVol, cr)
+	if err != nil {
+		if _, ok := err.(ErrImageNotFound); !ok {
+			klog.Errorf(util.Log(ctx, "failed to delete rbd image: %s/%s with error: %v"), rbdVol.Pool, rbdVol.VolName, err)
+			return err
+		}
+	}
+	return nil
+}
+
+func generateVolFromSnap(rbdSnap *rbdSnapshot) *rbdVolume {
+	vol := new(rbdVolume)
+	vol.ClusterID = rbdSnap.ClusterID
+	vol.VolID = rbdSnap.SnapID
+	vol.Monitors = rbdSnap.Monitors
+	vol.Pool = rbdSnap.Pool
+	vol.JournalPool = rbdSnap.JournalPool
+	vol.RbdImageName = rbdSnap.RbdSnapName
+	return vol
+}
+
+func undoSnapshotCloning(ctx context.Context, parentVol *rbdVolume, rbdSnap *rbdSnapshot, cloneVol *rbdVolume, cr *util.Credentials) error {
+	err := cleanUpSnapshot(ctx, parentVol, rbdSnap, cloneVol, cr)
+	if err != nil {
+		klog.Errorf(util.Log(ctx, "failed to clean up  %s or %s: %v"), cloneVol, rbdSnap, err)
+		return err
+	}
+	err = undoSnapReservation(ctx, rbdSnap, cr)
+	return err
+}