fix(CSI-224,WEKAPP-417375): race condition on multiple volume deletion in parallel

Dockerfile

@@ -31,6 +31,8 @@ RUN apk add util-linux libselinux libselinux-utils util-linux pciutils usbutils
 # Update CA certificates
 RUN apk add ca-certificates
 RUN update-ca-certificates
+ADD https://github.com/tigrawap/locar/releases/download/0.4.0/locar_linux_amd64 /locar
+RUN chmod +x /locar
 COPY --from=go-builder /bin/wekafsplugin /wekafsplugin
 ARG binary=/bin/wekafsplugin
 ENTRYPOINT ["/wekafsplugin"]

pkg/wekafs/gc.go

@@ -2,16 +2,21 @@ package wekafs
 
 import (
 	"context"
+	"fmt"
 	"github.com/rs/zerolog/log"
 	"github.com/wekafs/csi-wekafs/pkg/wekafs/apiclient"
+	"go.opentelemetry.io/otel"
 	"io"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"sync"
 )
 
 const garbagePath = ".__internal__wekafs-async-delete"
 
+//const garbageCollectionMaxThreads = 32
+
 type innerPathVolGc struct {
 	isRunning  map[string]bool
 	isDeferred map[string]bool
@@ -26,42 +31,36 @@ func initInnerPathVolumeGc(mounter *wekaMounter) *innerPathVolGc {
 	return &gc
 }
 
-func (gc *innerPathVolGc) triggerGc(ctx context.Context, fs string, apiClient *apiclient.ApiClient) {
-	gc.Lock()
-	defer gc.Unlock()
-	if gc.isRunning[fs] {
-		gc.isDeferred[fs] = true
-		return
-	}
-	gc.isRunning[fs] = true
-	go gc.purgeLeftovers(ctx, fs, apiClient)
-}
-
 func (gc *innerPathVolGc) triggerGcVolume(ctx context.Context, volume *Volume) {
-	fsName := volume.FilesystemName
-	gc.Lock()
-	defer gc.Unlock()
-	if gc.isRunning[fsName] {
-		gc.isDeferred[fsName] = true
-		return
-	}
-	gc.isRunning[fsName] = true
-	gc.isDeferred[fsName] = true
-	go gc.purgeVolume(ctx, volume)
+	op := "triggerGcVolume"
+	ctx, span := otel.Tracer(TracerName).Start(ctx, op)
+	defer span.End()
+	ctx = log.With().Str("trace_id", span.SpanContext().TraceID().String()).Str("span_id", span.SpanContext().SpanID().String()).Str("op", op).Logger().WithContext(ctx)
+	logger := log.Ctx(ctx).With().Str("volume_id", volume.GetId()).Logger()
+	logger.Info().Msg("Triggering garbage collection of volume")
+	gc.moveVolumeToTrash(ctx, volume) // always do it synchronously
 }
 
-func (gc *innerPathVolGc) purgeVolume(ctx context.Context, volume *Volume) {
+func (gc *innerPathVolGc) moveVolumeToTrash(ctx context.Context, volume *Volume) {
+	op := "moveVolumeToTrash"
+	ctx, span := otel.Tracer(TracerName).Start(ctx, op)
+	defer span.End()
+	ctx = log.With().Str("trace_id", span.SpanContext().TraceID().String()).Str("span_id", span.SpanContext().SpanID().String()).Str("op", op).Logger().WithContext(ctx)
 	logger := log.Ctx(ctx).With().Str("volume_id", volume.GetId()).Logger()
 	logger.Debug().Msg("Starting garbage collection of volume")
 	fsName := volume.FilesystemName
-	defer gc.finishGcCycle(ctx, fsName, volume.apiClient)
+	defer gc.initiateGarbageCollection(ctx, fsName, volume.apiClient)
 	path, err, unmount := gc.mounter.Mount(ctx, fsName, volume.apiClient)
 	defer unmount()
+	if err != nil {
+		logger.Error().Err(err).Msg("Failed to mount filesystem for GC processing")
+		return
+	}
 	volumeTrashLoc := filepath.Join(path, garbagePath)
 	if err := os.MkdirAll(volumeTrashLoc, DefaultVolumePermissions); err != nil {
-		logger.Error().Err(err).Msg("Failed to create garbage collector directory")
+		logger.Error().Str("garbage_collection_path", volumeTrashLoc).Err(err).Msg("Failed to create garbage collector directory")
 	} else {
-		logger.Debug().Str("garbage_collection_path", volumeTrashLoc).Msg("Successfuly created garbage collection directory")
+		logger.Debug().Str("garbage_collection_path", volumeTrashLoc).Msg("Successfully created garbage collection directory")
 	}
 	fullPath := filepath.Join(path, volume.GetFullPath(ctx))
 	logger.Debug().Str("full_path", fullPath).Str("volume_trash_location", volumeTrashLoc).Msg("Moving volume contents to trash")
@@ -75,65 +74,70 @@ func (gc *innerPathVolGc) purgeVolume(ctx context.Context, volume *Volume) {
 	// so if the volume is dir/v1/<filesystem>/this/is/a/path/to/volume, we might move only the `volume`
 	// but otherwise it could be risky as if we have multiple volumes we might remove other data too, e.g.
 	// vol1: dir/v1/<filesystem>/this/is/a/path/to/volume, vol2: dir/v1/<filesystem>/this/is/a/path/to/another_volume
-
-	logger.Trace().Str("purge_path", volumeTrashLoc).Msg("Purging deleted volume data")
-	if err != nil {
-		logger.Error().Err(err).Msg("Failed to mount filesystem for GC processing")
-		return
-	}
-	if err := purgeDirectory(ctx, volumeTrashLoc); err != nil {
-		logger.Error().Err(err).Str("purge_path", volumeTrashLoc).Msg("Failed to remove directory")
-		return
-	}
-
-	logger.Debug().Msg("Volume purged")
-}
-
-func purgeDirectory(ctx context.Context, path string) error {
-	logger := log.Ctx(ctx).With().Str("path", path).Logger()
-	if !PathExists(path) {
-		logger.Error().Str("path", path).Msg("Failed to remove existing directory")
-		return nil
-	}
-	for !pathIsEmptyDir(path) { // to make sure that if new files still appeared during invocation
-		files, err := os.ReadDir(path)
-		if err != nil {
-			logger.Error().Err(err).Msg("GC failed to read directory contents")
-			return err
-		}
-		for _, f := range files {
-			fp := filepath.Join(path, f.Name())
-			if f.IsDir() {
-				if err := purgeDirectory(ctx, fp); err != nil {
-					logger.Error().Err(err).Msg("")
-					return err
-				}
-			} else if err := os.Remove(fp); err != nil {
-				logger.Error().Err(err).Msg("Failed to remove directory that was used mount point")
-			}
-		}
-	}
-	return os.Remove(path)
+	// 2024-07-29: apparently seems this is not a real problem since static volumes are not deleted this way
+	//             and dynamic volumes are always created inside the /csi-volumes
+	logger.Debug().Str("full_path", fullPath).Str("volume_trash_location", volumeTrashLoc).Msg("Volume contents moved to trash")
 }
 
 func (gc *innerPathVolGc) purgeLeftovers(ctx context.Context, fs string, apiClient *apiclient.ApiClient) {
-	defer gc.finishGcCycle(ctx, fs, apiClient)
+	op := "purgeLeftovers"
+	ctx, span := otel.Tracer(TracerName).Start(ctx, op)
+	defer span.End()
+	ctx = log.With().Str("trace_id", span.SpanContext().TraceID().String()).Str("span_id", span.SpanContext().SpanID().String()).Str("op", op).Logger().WithContext(ctx)
+	logger := log.Ctx(ctx)
+	gc.Lock()
+	gc.isRunning[fs] = true
+	gc.Unlock()
 	path, err, unmount := gc.mounter.Mount(ctx, fs, apiClient)
 	defer unmount()
 	if err != nil {
 		log.Ctx(ctx).Error().Err(err).Str("filesystem", fs).Str("path", path).Msg("Failed mounting FS for garbage collection")
 		return
 	}
-}
+	volumeTrashLoc := filepath.Join(path, garbagePath)
 
-func (gc *innerPathVolGc) finishGcCycle(ctx context.Context, fs string, apiClient *apiclient.ApiClient) {
+	if fileExists("/locar") {
+		logger.Debug().Msg("Using locar for fast deletion")
+		deleteCmd := exec.Command("bash", "-c", fmt.Sprintf("/locar --type dir %s | /usr/bin/xargs -P32 -n128 rm -rf", volumeTrashLoc))
+		output, err := deleteCmd.CombinedOutput()
+		if err != nil {
+			logger.Error().Err(err).Msg("Error running locar")
+			logger.Trace().Str("output", string(output)).Msg("Locar output")
+		}
+	} else {
+		logger.Debug().Msg("Using default deletion method")
+		if err := os.RemoveAll(volumeTrashLoc); err != nil {
+			logger.Error().Err(err).Str("path", volumeTrashLoc).Msg("Failed to perform garbage collection")
+		}
+	}
+	logger.Debug().Msg("Garbage collection completed")
 	gc.Lock()
+	defer gc.Unlock()
 	gc.isRunning[fs] = false
 	if gc.isDeferred[fs] {
 		gc.isDeferred[fs] = false
-		go gc.triggerGc(ctx, fs, apiClient)
+		go gc.purgeLeftovers(ctx, fs, apiClient)
+	}
+}
+
+func (gc *innerPathVolGc) initiateGarbageCollection(ctx context.Context, fs string, apiClient *apiclient.ApiClient) {
+	op := "initiateGarbageCollection"
+	ctx, span := otel.Tracer(TracerName).Start(ctx, op)
+	defer span.End()
+	ctx = log.With().Str("trace_id", span.SpanContext().TraceID().String()).Str("span_id", span.SpanContext().SpanID().String()).Str("op", op).Logger().WithContext(ctx)
+	logger := log.Ctx(ctx)
+	logger.Trace().Msg("Initiating garbage collection")
+	gc.Lock()
+	defer gc.Unlock()
+	if gc.isRunning[fs] {
+		logger.Trace().Msg("Garbage collection already running, deferring next run")
+		gc.isDeferred[fs] = true
+		return
+	}
+	if !gc.isDeferred[fs] {
+		logger.Trace().Msg("Garbage collection not running, starting")
+		go gc.purgeLeftovers(ctx, fs, apiClient)
 	}
-	gc.Unlock()
 }
 
 // pathIsEmptyDir is a simple check to determine if directory is empty or not.

pkg/wekafs/utilities.go

@@ -270,6 +270,17 @@ func PathExists(p string) bool {
 	return true
 }
 
+func fileExists(filename string) bool {
+	_, err := os.Stat(filename)
+	if err == nil {
+		return true
+	}
+	if os.IsNotExist(err) {
+		return false
+	}
+	return false
+}
+
 func PathIsWekaMount(ctx context.Context, path string) bool {
 	file, err := os.Open("/proc/mounts")
 	if err != nil {