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rbd: fix resync issue
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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>
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@Madhu-1
Madhu-1 committed Aug 24, 2023
1 parent 88ccd84 commit f27714e
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Showing 4 changed files with 110 additions and 111 deletions.
100 changes: 81 additions & 19 deletions internal/csi-addons/rbd/replication.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,11 @@ const (
// imageMirrorModeJournal uses journaling to propagate RBD images between
// ceph clusters.
imageMirrorModeJournal imageMirroringMode = "journal"

// imageCreationTimeKey is the key to get/set the image creation timestamp
// on the image metadata. The key is starting with `.rbd` so that it will
// not get replicated to remote cluster.
imageCreationTimeKey = ".rbd.image.creation_time"
)

const (
Expand Down Expand Up @@ -480,6 +485,14 @@ 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())
}

mirroringInfo, err := rbdVol.GetImageMirroringInfo()
if err != nil {
log.ErrorLog(ctx, err.Error())
Expand All @@ -497,6 +510,17 @@ func (rs *ReplicationServer) DemoteVolume(ctx context.Context,

// demote image to secondary
if mirroringInfo.Primary {
// store the image creation time for resync
_, err = rbdVol.GetMetadata(imageCreationTimeKey)
if err != nil && errors.Is(err, librbd.ErrNotFound) {
err = rbdVol.SetMetadata(imageCreationTimeKey, creationTime.String())
}
if err != nil {
log.ErrorLog(ctx, err.Error())

return nil, status.Error(codes.Internal, err.Error())
}

err = rbdVol.DemoteImage()
if err != nil {
log.ErrorLog(ctx, err.Error())
Expand Down Expand Up @@ -538,6 +562,8 @@ 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) {
Expand Down Expand Up @@ -578,7 +604,7 @@ func (rs *ReplicationServer) ResyncVolume(ctx context.Context,
// it takes time for this operation.
log.ErrorLog(ctx, err.Error())

return nil, status.Error(codes.Aborted, err.Error())
return nil, status.Errorf(codes.Aborted, err.Error())
}

if mirroringInfo.State != librbd.MirrorImageEnabled {
Expand Down Expand Up @@ -637,14 +663,53 @@ 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)
// image creation time is stored in the image metadata. it looks like
// `"seconds:1692879841 nanos:631526669"`
savedImageTime, err := rbdVol.GetMetadata(imageCreationTimeKey)
if err != nil {
return nil, status.Error(codes.Internal, err.Error())
return nil, status.Errorf(codes.Internal, "failed to get image creation time: %s", err.Error())
}

parts := strings.Fields(savedImageTime)
if len(parts) != 2 {
return nil, status.Errorf(codes.Internal, "failed to parse image creation time: %s", savedImageTime)
}
if len(strings.Split(parts[0], ":")) != 2 || len(strings.Split(parts[1], ":")) != 2 {
return nil, status.Errorf(codes.Internal, "failed to parse image creation time: %s", savedImageTime)
}
secondsStr := strings.Split(parts[0], ":")[1]
nanosStr := strings.Split(parts[1], ":")[1]

seconds, err := strconv.ParseInt(secondsStr, 10, 64)
if err != nil {
return nil, status.Errorf(codes.Internal, "failed to parse image creation time seconds: %s", err.Error())
}

nanos, err := strconv.ParseInt(nanosStr, 10, 32)
if err != nil {
return nil, status.Errorf(codes.Internal, "failed to parse image creation time nenos: %s", err.Error())
}

st := time.Unix(seconds, nanos)
log.DebugLog(ctx, "image %s, savedImageTime=%v, currentImageTime=%v", rbdVol, st, creationTime.AsTime())

if req.Force && st.Equal(creationTime.AsTime()) {
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)
Expand Down Expand Up @@ -854,20 +919,17 @@ 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
Expand Down
66 changes: 9 additions & 57 deletions internal/csi-addons/rbd/replication_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
},
Expand Down
13 changes: 13 additions & 0 deletions internal/rbd/rbd_util.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
}
if err := ri.getImageInfo(); 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 {
Expand Down
42 changes: 7 additions & 35 deletions internal/rbd/replication.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand All @@ -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,
Expand Down

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