rbd: fix resync issue

During the Demote volume store
the image creation timestamp.

During Resync do below operation

* Check image creation timestamp
stored during Demote operation
and current creation timestamp during Resync
and check both are equal and its for
force resync then issue resync
* If the image on both sides is
not in unknown state, check
last_snapshot_timestamp on the
local mirror description, if its present
send volumeReady as false or else return
error message.

If both the images are in up+unknown the
send volumeReady as true.

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

internal/csi-addons/rbd/replication.go

@@ -24,6 +24,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	corerbd "github.com/ceph/ceph-csi/internal/rbd"
@@ -40,6 +41,12 @@ import (
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
+// imageResyncMap is used to store the volumeID and image creation time for resync.
+// The volumeID gets added to the map when the DemoteVolume RPC is called and
+// removed from the map when the PromoteVolume RPC is called or
+// DisableVolumeReplication RPC is called.
+var imageResyncMap = sync.Map{}
+
 // imageMirroringMode is used to indicate the mirroring mode for an RBD image.
 type imageMirroringMode string
 
@@ -337,11 +344,15 @@ func (rs *ReplicationServer) DisableVolumeReplication(ctx context.Context,
 		if err != nil {
 			return nil, getGRPCError(err)
 		}
+		imageResyncMap.Delete(volumeID)
 
 		return &replication.DisableVolumeReplicationResponse{}, nil
 	default:
 		return nil, status.Errorf(codes.InvalidArgument, "image is in %s Mode", mirroringInfo.State)
 	}
+	// remove the volume from the resync map as the image mirroring is disabled and
+	// during next Demote operation cephcsi will re-add the image to the sync map
+	imageResyncMap.Delete(volumeID)
 
 	return &replication.DisableVolumeReplicationResponse{}, nil
 }
@@ -439,6 +450,13 @@ func (rs *ReplicationServer) PromoteVolume(ctx context.Context,
 			rbdVol)
 	}
 
+	// remove the volume from the resync map as the image is promoted and
+	// during next Demote operation cephcsi will re-add the image to the sync
+	// map.
+	// This is required if someone does not do DisableVolumeReplication but try
+	// to toggle between PromoteVolume and DemoteVolume.
+	imageResyncMap.Delete(volumeID)
+
 	return &replication.PromoteVolumeResponse{}, nil
 }
 
@@ -480,6 +498,18 @@ func (rs *ReplicationServer) DemoteVolume(ctx context.Context,
 
 		return nil, err
 	}
+
+	creationTime, err := rbdVol.GetImageCreationTime()
+	if err != nil {
+		log.ErrorLog(ctx, err.Error())
+
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+	// store the image creation time for resync
+	if _, ok := imageResyncMap.Load(volumeID); !ok {
+		imageResyncMap.Store(volumeID, creationTime.AsTime())
+	}
+
 	mirroringInfo, err := rbdVol.GetImageMirroringInfo()
 	if err != nil {
 		log.ErrorLog(ctx, err.Error())
@@ -538,6 +568,8 @@ func checkRemoteSiteStatus(ctx context.Context, mirrorStatus *librbd.GlobalMirro
 // ResyncVolume extracts the RBD volume information from the volumeID, If the
 // image is present, mirroring is enabled and the image is in demoted state.
 // If yes it will resync the image to correct the split-brain.
+//
+//nolint:gocyclo,cyclop // TODO: reduce complexity
 func (rs *ReplicationServer) ResyncVolume(ctx context.Context,
 	req *replication.ResyncVolumeRequest,
 ) (*replication.ResyncVolumeResponse, error) {
@@ -572,22 +604,11 @@ func (rs *ReplicationServer) ResyncVolume(ctx context.Context,
 		return nil, err
 	}
 
-	mirroringInfo, err := rbdVol.GetImageMirroringInfo()
+	err = rbdVol.CheckImageIsPrimary()
 	if err != nil {
-		// in case of Resync the image will get deleted and gets recreated and
-		// it takes time for this operation.
 		log.ErrorLog(ctx, err.Error())
 
-		return nil, status.Error(codes.Aborted, err.Error())
-	}
-
-	if mirroringInfo.State != librbd.MirrorImageEnabled {
-		return nil, status.Error(codes.InvalidArgument, "image mirroring is not enabled")
-	}
-
-	// return error if the image is still primary
-	if mirroringInfo.Primary {
-		return nil, status.Error(codes.InvalidArgument, "image is in primary state")
+		return nil, getGRPCError(err)
 	}
 
 	mirrorStatus, err := rbdVol.GetImageMirroringStatus()
@@ -637,14 +658,28 @@ func (rs *ReplicationServer) ResyncVolume(ctx context.Context,
 		ready = checkRemoteSiteStatus(ctx, mirrorStatus)
 	}
 
-	err = rbdVol.ResyncVol(localStatus, req.Force)
+	creationTime, err := rbdVol.GetImageCreationTime()
 	if err != nil {
-		return nil, getGRPCError(err)
+		return nil, status.Errorf(codes.Internal, "failed to get image info: %s", err.Error())
 	}
 
-	err = checkVolumeResyncStatus(localStatus)
+	ok, err := resyncVolume(ctx, volumeID, creationTime)
 	if err != nil {
-		return nil, status.Error(codes.Internal, err.Error())
+		return nil, status.Errorf(codes.Internal, "failed to check image needs resync: %s", err.Error())
+	}
+
+	if req.Force && ok {
+		err = rbdVol.ResyncVol(localStatus)
+		if err != nil {
+			return nil, getGRPCError(err)
+		}
+	}
+
+	if !ready {
+		err = checkVolumeResyncStatus(localStatus)
+		if err != nil {
+			return nil, status.Error(codes.Internal, err.Error())
+		}
 	}
 
 	err = rbdVol.RepairResyncedImageID(ctx, ready)
@@ -659,6 +694,29 @@ func (rs *ReplicationServer) ResyncVolume(ctx context.Context,
 	return resp, nil
 }
 
+func resyncVolume(
+	ctx context.Context,
+	volumeID string,
+	currentImageTime *timestamppb.Timestamp,
+) (bool, error) {
+	savedImageTime, ok := imageResyncMap.Load(volumeID)
+	if !ok {
+		return false, errors.New("failed to get image creation time")
+	}
+
+	log.UsefulLog(ctx, "savedImageTime=%v, currentImageTime=%v", savedImageTime, currentImageTime)
+	st, ok := savedImageTime.(time.Time)
+	if !ok {
+		return false, errors.New("failed to convert image creation time")
+	}
+
+	if st.Equal(currentImageTime.AsTime()) {
+		return true, nil
+	}
+
+	return false, nil
+}
+
 func getGRPCError(err error) error {
 	if err == nil {
 		return status.Error(codes.OK, codes.OK.String())
@@ -854,20 +912,17 @@ func getLastSyncInfo(description string) (*replication.GetVolumeReplicationInfoR
 }
 
 func checkVolumeResyncStatus(localStatus librbd.SiteMirrorImageStatus) error {
-	// we are considering 2 states to check resync started and resync completed
-	// as below. all other states will be considered as an error state so that
-	// cephCSI can return error message and volume replication operator can
-	// mark the VolumeReplication status as not resyncing for the volume.
-
-	// If the state is Replaying means the resync is going on.
-	// Once the volume on remote cluster is demoted and resync
-	// is completed the image state will be moved to UNKNOWN.
-	// RBD mirror daemon should be always running on the primary cluster.
-	if !localStatus.Up || (localStatus.State != librbd.MirrorImageStatusStateReplaying &&
-		localStatus.State != librbd.MirrorImageStatusStateUnknown) {
-		return fmt.Errorf(
-			"not resyncing. Local status: daemon up=%t image is in %q state",
-			localStatus.Up, localStatus.State)
+	// we are considering local snapshot timestamp to check if the resync is
+	// started or not, if we dont see local_snapshot_timestamp in the
+	// description of localStatus, we are returning error. if we see the local
+	// snapshot timestamp in the description we return resyncing started.
+	description := localStatus.Description
+	resp, err := getLastSyncInfo(description)
+	if err != nil {
+		return fmt.Errorf("failed to get last sync info: %w", err)
+	}
+	if resp.LastSyncTime == nil {
+		return errors.New("last sync time is nil")
 	}
 
 	return nil

internal/csi-addons/rbd/replication_test.go

@@ -225,74 +225,26 @@ func TestCheckVolumeResyncStatus(t *testing.T) {
 		wantErr bool
 	}{
 		{
-			name: "test when rbd mirror daemon is not running",
+			name: "test when local_snapshot_timestamp is non zero",
 			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateUnknown,
-				Up:    false,
-			},
-			wantErr: true,
-		},
-		{
-			name: "test for unknown state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateUnknown,
-				Up:    true,
-			},
-			wantErr: false,
-		},
-		{
-			name: "test for error state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateError,
-				Up:    true,
-			},
-			wantErr: true,
-		},
-		{
-			name: "test for syncing state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateSyncing,
-				Up:    true,
-			},
-			wantErr: true,
-		},
-		{
-			name: "test for starting_replay state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateStartingReplay,
-				Up:    true,
-			},
-			wantErr: true,
-		},
-		{
-			name: "test for replaying state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateReplaying,
-				Up:    true,
+				//nolint:lll // sample output cannot be split into multiple lines.
+				Description: `replaying, {"bytes_per_second":0.0,"bytes_per_snapshot":81920.0,"last_snapshot_bytes":81920,"last_snapshot_sync_seconds":56743,"local_snapshot_timestamp":1684675261,"remote_snapshot_timestamp":1684675261,"replay_state":"idle"}`,
 			},
 			wantErr: false,
 		},
 		{
-			name: "test for stopping_replay state",
-			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateStoppingReplay,
-				Up:    true,
-			},
-			wantErr: true,
-		},
-		{
-			name: "test for stopped state",
+			name: "test when local_snapshot_timestamp is zero",
+			//nolint:lll // sample output cannot be split into multiple lines.
 			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusStateStopped,
-				Up:    true,
+				Description: `replaying, {"bytes_per_second":0.0,"bytes_per_snapshot":81920.0,"last_snapshot_bytes":81920,"last_snapshot_sync_seconds":56743,"local_snapshot_timestamp":0,"remote_snapshot_timestamp":1684675261,"replay_state":"idle"}`,
 			},
 			wantErr: true,
 		},
 		{
-			name: "test for invalid state",
+			name: "test when local_snapshot_timestamp is not present",
+			//nolint:lll // sample output cannot be split into multiple lines.
 			args: librbd.SiteMirrorImageStatus{
-				State: librbd.MirrorImageStatusState(100),
-				Up:    true,
+				Description: `replaying, {"bytes_per_second":0.0,"bytes_per_snapshot":81920.0,"last_snapshot_bytes":81920,"last_snapshot_sync_seconds":56743,"remote_snapshot_timestamp":1684675261,"replay_state":"idle"}`,
 			},
 			wantErr: true,
 		},

internal/rbd/rbd_util.go

@@ -1558,6 +1558,19 @@ func (rv *rbdVolume) setImageOptions(ctx context.Context, options *librbd.ImageO
 	return nil
 }
 
+// getImageCreationTime returns the creation time of the image. if the image
+// creation time is not set, it queries the image info and returns the creation time.
+func (ri *rbdImage) GetImageCreationTime() (*timestamppb.Timestamp, error) {
+	if ri.CreatedAt != nil {
+		return ri.CreatedAt, nil
+	}
+	err := ri.getImageInfo()
+	if err != nil {
+		return nil, err
+	}
+	return ri.CreatedAt, nil
+}
+
 // getImageInfo queries rbd about the given image and returns its metadata, and returns
 // ErrImageNotFound if provided image is not found.
 func (ri *rbdImage) getImageInfo() error {

internal/rbd/replication.go

@@ -19,31 +19,19 @@ package rbd
 import (
 	"context"
 	"fmt"
-	"strings"
 
 	librbd "github.com/ceph/go-ceph/rbd"
 )
 
-func (rv *rbdVolume) ResyncVol(localStatus librbd.SiteMirrorImageStatus, force bool) error {
-	if resyncRequired(localStatus) {
-		// If the force option is not set return the error message to retry
-		// with Force option.
-		if !force {
-			return fmt.Errorf("%w: image is in %q state, description (%s). Force resync to recover volume",
-				ErrFailedPrecondition, localStatus.State, localStatus.Description)
-		}
-		err := rv.resyncImage()
-		if err != nil {
-			return fmt.Errorf("%w: failed to resync image: %w", ErrResyncImageFailed, err)
-		}
-
-		// If we issued a resync, return a non-final error as image needs to be recreated
-		// locally. Caller retries till RBD syncs an initial version of the image to
-		// report its status in the resync request.
-		return fmt.Errorf("%w: awaiting initial resync due to split brain", ErrUnavailable)
+func (rv *rbdVolume) ResyncVol(localStatus librbd.SiteMirrorImageStatus) error {
+	if err := rv.resyncImage(); err != nil {
+		return fmt.Errorf("%w: failed to resync image: %w", ErrResyncImageFailed, err)
 	}
 
-	return nil
+	// If we issued a resync, return a non-final error as image needs to be recreated
+	// locally. Caller retries till RBD syncs an initial version of the image to
+	// report its status in the resync request.
+	return fmt.Errorf("%w: awaiting initial resync due to split brain", ErrUnavailable)
 }
 
 // repairResyncedImageID updates the existing image ID with new one.
@@ -66,22 +54,6 @@ func (rv *rbdVolume) RepairResyncedImageID(ctx context.Context, ready bool) erro
 	return rv.repairImageID(ctx, j, true)
 }
 
-// resyncRequired returns true if local image is in split-brain state and image
-// needs resync.
-func resyncRequired(localStatus librbd.SiteMirrorImageStatus) bool {
-	// resync is required if the image is in error state or the description
-	// contains split-brain message.
-	// In some corner cases like `re-player shutdown` the local image will not
-	// be in an error state. It would be also worth considering the `description`
-	// field to make sure about split-brain.
-	if localStatus.State == librbd.MirrorImageStatusStateError ||
-		strings.Contains(localStatus.Description, "split-brain") {
-		return true
-	}
-
-	return false
-}
-
 func (rv *rbdVolume) DisableVolumeReplication(
 	mirroringInfo *librbd.MirrorImageInfo,
 	force bool,
@@ -126,3 +98,23 @@ func (rv *rbdVolume) DisableVolumeReplication(
 
 	return nil
 }
+
+func (rv *rbdVolume) CheckImageIsPrimary() error {
+	mirroringInfo, err := rv.GetImageMirroringInfo()
+	if err != nil {
+		// in case of Resync the image will get deleted and gets recreated and
+		// it takes time for this operation.
+		return fmt.Errorf("%w: %w", ErrAborted, err)
+	}
+
+	if mirroringInfo.State != librbd.MirrorImageEnabled {
+		return fmt.Errorf("%w: image mirroring is not enabled", ErrInvalidArgument)
+	}
+
+	// return error if the image is still primary
+	if mirroringInfo.Primary {
+		return fmt.Errorf("%w: image is in primary state", ErrInvalidArgument)
+	}
+
+	return nil
+}