refactor: gcs storage driver (#4120)

registry/storage/driver/gcs/gcs.go

@@ -27,7 +27,6 @@ import (
 	"os"
 	"reflect"
 	"regexp"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -49,12 +48,14 @@ const (
 	driverName     = "gcs"
 	dummyProjectID = "<unknown>"
 
-	uploadSessionContentType = "application/x-docker-upload-session"
 	minChunkSize          = 256 * 1024
-	defaultChunkSize         = 20 * minChunkSize
+	defaultChunkSize      = 16 * 1024 * 1024
 	defaultMaxConcurrency = 50
 	minConcurrency        = 25
 
+	uploadSessionContentType = "application/x-docker-upload-session"
+	blobContentType          = "application/octet-stream"
+
 	maxTries = 5
 )
 
@@ -97,12 +98,11 @@ var _ storagedriver.StorageDriver = &driver{}
 // Objects are stored at absolute keys in the provided bucket.
 type driver struct {
 	client        *http.Client
-	bucket        string
+	bucket        *storage.BucketHandle
 	email         string
 	privateKey    []byte
 	rootDirectory string
 	chunkSize     int
-	gcs           *storage.Client
 }
 
 // Wrapper wraps `driver` with a throttler, ensuring that no more than N
@@ -136,7 +136,7 @@ func FromParameters(ctx context.Context, parameters map[string]interface{}) (sto
 		case string:
 			vv, err := strconv.Atoi(v)
 			if err != nil {
-				return nil, fmt.Errorf("chunksize parameter must be an integer, %v invalid", chunkSizeParam)
+				return nil, fmt.Errorf("chunksize must be an integer, %v invalid", chunkSizeParam)
 			}
 			chunkSize = vv
 		case int, uint, int32, uint32, uint64, int64:
@@ -146,7 +146,7 @@ func FromParameters(ctx context.Context, parameters map[string]interface{}) (sto
 		}
 
 		if chunkSize < minChunkSize {
-			return nil, fmt.Errorf("The chunksize %#v parameter should be a number that is larger than or equal to %d", chunkSize, minChunkSize)
+			return nil, fmt.Errorf("chunksize %#v must be larger than or equal to %d", chunkSize, minChunkSize)
 		}
 
 		if chunkSize%minChunkSize != 0 {
@@ -203,10 +203,17 @@ func FromParameters(ctx context.Context, parameters map[string]interface{}) (sto
 		}
 	} else {
 		var err error
+		// DefaultTokenSource is a convenience method. It first calls FindDefaultCredentials,
+		// then uses the credentials to construct an http.Client or an oauth2.TokenSource.
+		// https://pkg.go.dev/golang.org/x/oauth2/google#hdr-Credentials
 		ts, err = google.DefaultTokenSource(ctx, storage.ScopeFullControl)
 		if err != nil {
 			return nil, err
 		}
+		gcs, err = storage.NewClient(ctx)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	maxConcurrency, err := base.GetLimitFromParameter(parameters["maxconcurrency"], minConcurrency, defaultMaxConcurrency)
@@ -214,9 +221,6 @@ func FromParameters(ctx context.Context, parameters map[string]interface{}) (sto
 		return nil, fmt.Errorf("maxconcurrency config error: %s", err)
 	}
 
-	if gcs == nil {
-		panic("gcs client was nil")
-	}
 	params := driverParameters{
 		bucket:         fmt.Sprint(bucket),
 		rootDirectory:  fmt.Sprint(rootDirectory),
@@ -241,13 +245,12 @@ func New(ctx context.Context, params driverParameters) (storagedriver.StorageDri
 		return nil, fmt.Errorf("Invalid chunksize: %d is not a positive multiple of %d", params.chunkSize, minChunkSize)
 	}
 	d := &driver{
-		bucket:        params.bucket,
+		bucket:        params.gcs.Bucket(params.bucket),
 		rootDirectory: rootDirectory,
 		email:         params.email,
 		privateKey:    params.privateKey,
 		client:        params.client,
 		chunkSize:     params.chunkSize,
-		gcs:           params.gcs,
 	}
 
 	return &Wrapper{
@@ -268,21 +271,16 @@ func (d *driver) Name() string {
 // GetContent retrieves the content stored at "path" as a []byte.
 // This should primarily be used for small objects.
 func (d *driver) GetContent(ctx context.Context, path string) ([]byte, error) {
-	name := d.pathToKey(path)
+	r, err := d.bucket.Object(d.pathToKey(path)).NewReader(ctx)
-	rc, err := d.gcs.Bucket(d.bucket).Object(name).NewReader(ctx)
+	if err != nil {
 		if err == storage.ErrObjectNotExist {
 			return nil, storagedriver.PathNotFoundError{Path: path}
 		}
-	if err != nil {
 		return nil, err
 	}
-	defer rc.Close()
+	defer r.Close()
 
-	p, err := io.ReadAll(rc)
+	return io.ReadAll(r)
-	if err != nil {
-		return nil, err
-	}
-	return p, nil
 }
 
 // PutContent stores the []byte content at a location designated by "path".
@@ -290,30 +288,38 @@ func (d *driver) GetContent(ctx context.Context, path string) ([]byte, error) {
 func (d *driver) PutContent(ctx context.Context, path string, contents []byte) error {
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
-	wc := d.gcs.Bucket(d.bucket).Object(d.pathToKey(path)).NewWriter(ctx)
+
-	wc.ContentType = "application/octet-stream"
+	object := d.bucket.Object(d.pathToKey(path))
-	return putContentsClose(wc, contents)
+	err := d.putContent(ctx, object, contents, blobContentType, nil)
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 // Reader retrieves an io.ReadCloser for the content stored at "path"
 // with a given byte offset.
 // May be used to resume reading a stream by providing a nonzero offset.
 func (d *driver) Reader(ctx context.Context, path string, offset int64) (io.ReadCloser, error) {
-	res, err := getObject(d.client, d.bucket, d.pathToKey(path), offset)
+	obj := d.bucket.Object(d.pathToKey(path))
+	// NOTE(milosgajdos): If length is negative, the object is read until the end
+	// See: https://pkg.go.dev/cloud.google.com/go/storage#ObjectHandle.NewRangeReader
+	r, err := obj.NewRangeReader(ctx, offset, -1)
 	if err != nil {
-		if res != nil {
+		if err == storage.ErrObjectNotExist {
-			if res.StatusCode == http.StatusNotFound {
-				res.Body.Close()
 			return nil, storagedriver.PathNotFoundError{Path: path}
 		}
-
+		var status *googleapi.Error
-			if res.StatusCode == http.StatusRequestedRangeNotSatisfiable {
+		if errors.As(err, &status) {
-				res.Body.Close()
+			switch status.Code {
-				obj, err := d.storageStatObject(ctx, path)
+			case http.StatusNotFound:
+				return nil, storagedriver.PathNotFoundError{Path: path}
+			case http.StatusRequestedRangeNotSatisfiable:
+				attrs, err := obj.Attrs(ctx)
 				if err != nil {
 					return nil, err
 				}
-				if offset == obj.Size {
+				if offset == attrs.Size {
 					return io.NopCloser(bytes.NewReader([]byte{})), nil
 				}
 				return nil, storagedriver.InvalidOffsetError{Path: path, Offset: offset}
@@ -321,77 +327,52 @@ func (d *driver) Reader(ctx context.Context, path string, offset int64) (io.Read
 		}
 		return nil, err
 	}
-	if res.Header.Get("Content-Type") == uploadSessionContentType {
+	if r.Attrs.ContentType == uploadSessionContentType {
-		defer res.Body.Close()
+		r.Close()
 		return nil, storagedriver.PathNotFoundError{Path: path}
 	}
-	return res.Body, nil
+	return r, nil
-}
-
-func getObject(client *http.Client, bucket string, name string, offset int64) (*http.Response, error) {
-	// copied from cloud.google.com/go/storage#NewReader :
-	// to set the additional "Range" header
-	u := &url.URL{
-		Scheme: "https",
-		Host:   "storage.googleapis.com",
-		Path:   fmt.Sprintf("/%s/%s", bucket, name),
-	}
-	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
-	if err != nil {
-		return nil, err
-	}
-	if offset > 0 {
-		req.Header.Set("Range", fmt.Sprintf("bytes=%v-", offset))
-	}
-	var res *http.Response
-	err = retry(func() error {
-		var err error
-		res, err = client.Do(req)
-		return err
-	})
-	if err != nil {
-		return nil, err
-	}
-	return res, googleapi.CheckMediaResponse(res)
 }
 
 // Writer returns a FileWriter which will store the content written to it
 // at the location designated by "path" after the call to Commit.
-func (d *driver) Writer(ctx context.Context, path string, append bool) (storagedriver.FileWriter, error) {
+func (d *driver) Writer(ctx context.Context, path string, appendMode bool) (storagedriver.FileWriter, error) {
-	writer := &writer{
+	w := &writer{
-		client: d.client,
+		ctx:    ctx,
-		bucket: d.bucket,
+		driver: d,
-		name:   d.pathToKey(path),
+		object: d.bucket.Object(d.pathToKey(path)),
 		buffer: make([]byte, d.chunkSize),
-		gcs:    d.gcs,
 	}
 
-	if append {
+	if appendMode {
-		err := writer.init(path)
+		err := w.init(ctx)
 		if err != nil {
 			return nil, err
 		}
 	}
-	return writer, nil
+	return w, nil
 }
 
 type writer struct {
-	client     *http.Client
+	ctx        context.Context
-	bucket     string
+	object     *storage.ObjectHandle
-	name       string
+	driver     *driver
 	size       int64
 	offset     int64
 	closed     bool
+	cancelled  bool
+	committed  bool
 	sessionURI string
 	buffer     []byte
 	buffSize   int
-	gcs        *storage.Client
 }
 
 // Cancel removes any written content from this FileWriter.
 func (w *writer) Cancel(ctx context.Context) error {
 	w.closed = true
-	err := storageDeleteObject(ctx, w.bucket, w.name, w.gcs)
+	w.cancelled = true
+
+	err := w.object.Delete(ctx)
 	if err != nil {
 		if err == storage.ErrObjectNotExist {
 			err = nil
@@ -406,7 +387,7 @@ func (w *writer) Close() error {
 	}
 	w.closed = true
 
-	err := w.writeChunk()
+	err := w.writeChunk(w.ctx)
 	if err != nil {
 		return err
 	}
@@ -420,37 +401,29 @@ func (w *writer) Close() error {
 	}
 
 	// commit the writes by updating the upload session
-	ctx := context.TODO()
+	metadata := map[string]string{
-	err = retry(func() error {
-		wc := w.gcs.Bucket(w.bucket).Object(w.name).NewWriter(ctx)
-		wc.ContentType = uploadSessionContentType
-		wc.Metadata = map[string]string{
 		"Session-URI": w.sessionURI,
 		"Offset":      strconv.FormatInt(w.offset, 10),
 	}
-		return putContentsClose(wc, w.buffer[0:w.buffSize])
+	err = retry(func() error {
-	})
+		err := w.driver.putContent(w.ctx, w.object, w.buffer[0:w.buffSize], uploadSessionContentType, metadata)
 		if err != nil {
 			return err
 		}
 		w.size = w.offset + int64(w.buffSize)
 		w.buffSize = 0
 		return nil
+	})
+	return err
 }
 
-func putContentsClose(wc *storage.Writer, contents []byte) error {
+func (d *driver) putContent(ctx context.Context, obj *storage.ObjectHandle, content []byte, contentType string, metadata map[string]string) error {
-	size := len(contents)
+	wc := obj.NewWriter(ctx)
-	var nn int
+	wc.Metadata = metadata
-	var err error
+	wc.ContentType = contentType
-	for nn < size {
+	wc.ChunkSize = d.chunkSize
-		var n int
+
-		n, err = wc.Write(contents[nn:size])
+	if _, err := bytes.NewReader(content).WriteTo(wc); err != nil {
-		nn += n
-		if err != nil {
-			break
-		}
-	}
-	if err != nil {
 		return err
 	}
 	return wc.Close()
@@ -460,54 +433,48 @@ func putContentsClose(wc *storage.Writer, contents []byte) error {
 // available for future calls to StorageDriver.GetContent and
 // StorageDriver.Reader.
 func (w *writer) Commit(ctx context.Context) error {
-	if err := w.checkClosed(); err != nil {
+	if w.closed {
-		return err
+		return fmt.Errorf("already closed")
 	}
 	w.closed = true
 
 	// no session started yet just perform a simple upload
 	if w.sessionURI == "" {
 		err := retry(func() error {
-			wc := w.gcs.Bucket(w.bucket).Object(w.name).NewWriter(ctx)
+			err := w.driver.putContent(ctx, w.object, w.buffer[0:w.buffSize], blobContentType, nil)
-			wc.ContentType = "application/octet-stream"
-			return putContentsClose(wc, w.buffer[0:w.buffSize])
-		})
 			if err != nil {
 				return err
 			}
+			w.committed = true
 			w.size = w.offset + int64(w.buffSize)
 			w.buffSize = 0
 			return nil
+		})
+		return err
 	}
 	size := w.offset + int64(w.buffSize)
-	var nn int
+	var written int
 	// loop must be performed at least once to ensure the file is committed even when
 	// the buffer is empty
 	for {
-		n, err := putChunk(w.client, w.sessionURI, w.buffer[nn:w.buffSize], w.offset, size)
+		n, err := w.putChunk(ctx, w.sessionURI, w.buffer[written:w.buffSize], w.offset, size)
-		nn += int(n)
+		written += int(n)
 		w.offset += n
 		w.size = w.offset
 		if err != nil {
-			w.buffSize = copy(w.buffer, w.buffer[nn:w.buffSize])
+			w.buffSize = copy(w.buffer, w.buffer[written:w.buffSize])
 			return err
 		}
-		if nn == w.buffSize {
+		if written == w.buffSize {
 			break
 		}
 	}
+	w.committed = true
 	w.buffSize = 0
 	return nil
 }
 
-func (w *writer) checkClosed() error {
+func (w *writer) writeChunk(ctx context.Context) error {
-	if w.closed {
-		return fmt.Errorf("Writer already closed")
-	}
-	return nil
-}
-
-func (w *writer) writeChunk() error {
 	var err error
 	// chunks can be uploaded only in multiples of minChunkSize
 	// chunkSize is a multiple of minChunkSize less than or equal to buffSize
@@ -517,42 +484,47 @@ func (w *writer) writeChunk() error {
 	}
 	// if their is no sessionURI yet, obtain one by starting the session
 	if w.sessionURI == "" {
-		w.sessionURI, err = startSession(w.client, w.bucket, w.name)
+		w.sessionURI, err = w.newSession()
 	}
 	if err != nil {
 		return err
 	}
-	nn, err := putChunk(w.client, w.sessionURI, w.buffer[0:chunkSize], w.offset, -1)
+	n, err := w.putChunk(ctx, w.sessionURI, w.buffer[0:chunkSize], w.offset, -1)
-	w.offset += nn
+	w.offset += n
 	if w.offset > w.size {
 		w.size = w.offset
 	}
 	// shift the remaining bytes to the start of the buffer
-	w.buffSize = copy(w.buffer, w.buffer[int(nn):w.buffSize])
+	w.buffSize = copy(w.buffer, w.buffer[int(n):w.buffSize])
 
 	return err
 }
 
 func (w *writer) Write(p []byte) (int, error) {
-	err := w.checkClosed()
+	if w.closed {
-	if err != nil {
+		return 0, fmt.Errorf("already closed")
-		return 0, err
+	} else if w.cancelled {
+		return 0, fmt.Errorf("already cancelled")
 	}
 
-	var nn int
+	var (
-	for nn < len(p) {
+		written int
-		n := copy(w.buffer[w.buffSize:], p[nn:])
+		err     error
+	)
+
+	for written < len(p) {
+		n := copy(w.buffer[w.buffSize:], p[written:])
 		w.buffSize += n
 		if w.buffSize == cap(w.buffer) {
-			err = w.writeChunk()
+			err = w.writeChunk(w.ctx)
 			if err != nil {
 				break
 			}
 		}
-		nn += n
+		written += n
 	}
 	w.size = w.offset + int64(w.buffSize)
-	return nn, err
+	return written, err
 }
 
 // Size returns the number of bytes written to this FileWriter.
@@ -560,25 +532,56 @@ func (w *writer) Size() int64 {
 	return w.size
 }
 
-func (w *writer) init(path string) error {
+func (w *writer) init(ctx context.Context) error {
-	res, err := getObject(w.client, w.bucket, w.name, 0)
+	attrs, err := w.object.Attrs(ctx)
 	if err != nil {
 		return err
 	}
-	defer res.Body.Close()
+
-	if res.Header.Get("Content-Type") != uploadSessionContentType {
+	// NOTE(milosgajdos): when PUSH abruptly finishes by
-		return storagedriver.PathNotFoundError{Path: path}
+	// calling a single commit and then closes the stream
+	// attrs.ContentType ends up being set to application/octet-stream
+	// We must handle this case so the upload can resume.
+	if attrs.ContentType != uploadSessionContentType &&
+		attrs.ContentType != blobContentType {
+		return storagedriver.PathNotFoundError{Path: w.object.ObjectName()}
 	}
-	offset, err := strconv.ParseInt(res.Header.Get("X-Goog-Meta-Offset"), 10, 64)
+
+	offset := int64(0)
+	// NOTE(milosgajdos): if a client creates an empty blob, then
+	// closes the stream and then attempts to append to it, the offset
+	// will be empty, in which case strconv.ParseInt will return error
+	// See: https://pkg.go.dev/strconv#ParseInt
+	if attrs.Metadata["Offset"] != "" {
+		offset, err = strconv.ParseInt(attrs.Metadata["Offset"], 10, 64)
 		if err != nil {
 			return err
 		}
-	buffer, err := io.ReadAll(res.Body)
+	}
+
+	r, err := w.object.NewReader(ctx)
 	if err != nil {
 		return err
 	}
-	w.sessionURI = res.Header.Get("X-Goog-Meta-Session-URI")
+	defer r.Close()
-	w.buffSize = copy(w.buffer, buffer)
+
+	for err == nil && w.buffSize < len(w.buffer) {
+		var n int
+		n, err = r.Read(w.buffer[w.buffSize:])
+		w.buffSize += n
+	}
+	if err != nil && err != io.EOF {
+		return err
+	}
+
+	// NOTE(milosgajdos): if a client closes an existing session and then attempts
+	// to append to an existing blob, the session will be empty; recreate it
+	if w.sessionURI = attrs.Metadata["Session-URI"]; w.sessionURI == "" {
+		w.sessionURI, err = w.newSession()
+		if err != nil {
+			return err
+		}
+	}
 	w.offset = offset
 	w.size = offset + int64(w.buffSize)
 	return nil
@@ -596,7 +599,7 @@ func retry(req request) error {
 		}
 
 		status, ok := err.(*googleapi.Error)
-		if !ok || (status.Code != 429 && status.Code < http.StatusInternalServerError) {
+		if !ok || (status.Code != http.StatusTooManyRequests && status.Code < http.StatusInternalServerError) {
 			return err
 		}
 
@@ -613,7 +616,7 @@ func retry(req request) error {
 func (d *driver) Stat(ctx context.Context, path string) (storagedriver.FileInfo, error) {
 	var fi storagedriver.FileInfoFields
 	// try to get as file
-	obj, err := d.storageStatObject(ctx, path)
+	obj, err := d.bucket.Object(d.pathToKey(path)).Attrs(ctx)
 	if err == nil {
 		if obj.ContentType == uploadSessionContentType {
 			return nil, storagedriver.PathNotFoundError{Path: path}
@@ -633,18 +636,19 @@ func (d *driver) Stat(ctx context.Context, path string) (storagedriver.FileInfo,
 		Prefix: dirpath,
 	}
 
-	objects, err := storageListObjects(ctx, d.bucket, query, d.gcs)
+	obj, err = d.bucket.Objects(ctx, query).Next()
 	if err != nil {
-		return nil, err
+		if err == iterator.Done {
-	}
-	if len(objects) < 1 {
 			return nil, storagedriver.PathNotFoundError{Path: path}
 		}
+		return nil, err
+	}
+
 	fi = storagedriver.FileInfoFields{
 		Path:  path,
 		IsDir: true,
 	}
-	obj = objects[0]
+
 	if obj.Name == dirpath {
 		fi.Size = obj.Size
 		fi.ModTime = obj.Updated
@@ -659,12 +663,17 @@ func (d *driver) List(ctx context.Context, path string) ([]string, error) {
 		Delimiter: "/",
 		Prefix:    d.pathToDirKey(path),
 	}
+	objects := d.bucket.Objects(ctx, query)
+
 	list := make([]string, 0, 64)
-	objects, err := storageListObjects(ctx, d.bucket, query, d.gcs)
+	for {
+		object, err := objects.Next()
 		if err != nil {
+			if err == iterator.Done {
+				break
+			}
 			return nil, err
 		}
-	for _, object := range objects {
 		// GCS does not guarantee strong consistency between
 		// DELETE and LIST operations. Check that the object is not deleted,
 		// and filter out any objects with a non-zero time-deleted
@@ -689,42 +698,51 @@ func (d *driver) List(ctx context.Context, path string) ([]string, error) {
 // Move moves an object stored at sourcePath to destPath, removing the
 // original object.
 func (d *driver) Move(ctx context.Context, sourcePath string, destPath string) error {
-	_, err := storageCopyObject(ctx, d.bucket, d.pathToKey(sourcePath), d.bucket, d.pathToKey(destPath), d.gcs)
+	srcKey, dstKey := d.pathToKey(sourcePath), d.pathToKey(destPath)
+	src := d.bucket.Object(srcKey)
+	_, err := d.bucket.Object(dstKey).CopierFrom(src).Run(ctx)
 	if err != nil {
-		if status, ok := err.(*googleapi.Error); ok {
+		var status *googleapi.Error
+		if errors.As(err, &status) {
 			if status.Code == http.StatusNotFound {
-				return storagedriver.PathNotFoundError{Path: sourcePath}
+				return storagedriver.PathNotFoundError{Path: srcKey}
 			}
 		}
-		return err
+		return fmt.Errorf("move %q to %q: %v", srcKey, dstKey, err)
 	}
-	err = storageDeleteObject(ctx, d.bucket, d.pathToKey(sourcePath), d.gcs)
+	err = src.Delete(ctx)
 	// if deleting the file fails, log the error, but do not fail; the file was successfully copied,
 	// and the original should eventually be cleaned when purging the uploads folder.
 	if err != nil {
-		logrus.Infof("error deleting file: %v due to %v", sourcePath, err)
+		logrus.Infof("error deleting %v: %v", sourcePath, err)
 	}
 	return nil
 }
 
 // listAll recursively lists all names of objects stored at "prefix" and its subpaths.
 func (d *driver) listAll(ctx context.Context, prefix string) ([]string, error) {
+	objects := d.bucket.Objects(ctx, &storage.Query{
+		Prefix:   prefix,
+		Versions: false,
+	})
+
 	list := make([]string, 0, 64)
-	query := &storage.Query{}
+	for {
-	query.Prefix = prefix
+		object, err := objects.Next()
-	query.Versions = false
-	objects, err := storageListObjects(ctx, d.bucket, query, d.gcs)
 		if err != nil {
+			if err == iterator.Done {
+				break
+			}
 			return nil, err
 		}
-	for _, obj := range objects {
 		// GCS does not guarantee strong consistency between
 		// DELETE and LIST operations. Check that the object is not deleted,
 		// and filter out any objects with a non-zero time-deleted
-		if obj.Deleted.IsZero() {
+		if object.Deleted.IsZero() {
-			list = append(list, obj.Name)
+			list = append(list, object.Name)
 		}
 	}
+
 	return list, nil
 }
 
@@ -736,9 +754,14 @@ func (d *driver) Delete(ctx context.Context, path string) error {
 		return err
 	}
 	if len(keys) > 0 {
-		sort.Sort(sort.Reverse(sort.StringSlice(keys)))
+		// NOTE(milosgajdos): d.listAll calls (BucketHandle).Objects
-		for _, key := range keys {
+		// See: https://pkg.go.dev/cloud.google.com/go/storage#BucketHandle.Objects
-			err := storageDeleteObject(ctx, d.bucket, key, d.gcs)
+		// docs: Objects will be iterated over lexicographically by name.
+		// This means we don't have to reverse order the slice; we can
+		// range over the keys slice in reverse order
+		for i := len(keys) - 1; i >= 0; i-- {
+			key := keys[i]
+			err := d.bucket.Object(key).Delete(ctx)
 			// GCS only guarantees eventual consistency, so listAll might return
 			// paths that no longer exist. If this happens, just ignore any not
 			// found error
@@ -753,62 +776,13 @@ func (d *driver) Delete(ctx context.Context, path string) error {
 		}
 		return nil
 	}
-	err = storageDeleteObject(ctx, d.bucket, d.pathToKey(path), d.gcs)
+	err = d.bucket.Object(d.pathToKey(path)).Delete(ctx)
 	if err == storage.ErrObjectNotExist {
 		return storagedriver.PathNotFoundError{Path: path}
 	}
 	return err
 }
 
-func storageDeleteObject(ctx context.Context, bucket string, name string, gcs *storage.Client) error {
-	return gcs.Bucket(bucket).Object(name).Delete(ctx)
-}
-
-func (d *driver) storageStatObject(ctx context.Context, name string) (*storage.ObjectAttrs, error) {
-	bkt := d.gcs.Bucket(d.bucket)
-	var obj *storage.ObjectAttrs
-	err := retry(func() error {
-		var err error
-		obj, err = bkt.Object(d.pathToKey(name)).Attrs(ctx)
-		return err
-	})
-	return obj, err
-}
-
-func storageListObjects(ctx context.Context, bucket string, q *storage.Query, gcs *storage.Client) ([]*storage.ObjectAttrs, error) {
-	bkt := gcs.Bucket(bucket)
-	var objs []*storage.ObjectAttrs
-	it := bkt.Objects(ctx, q)
-	for {
-		objAttrs, err := it.Next()
-		if err == iterator.Done {
-			break
-		}
-		if err != nil {
-			return nil, err
-		}
-		objs = append(objs, objAttrs)
-	}
-
-	return objs, nil
-}
-
-func storageCopyObject(ctx context.Context, srcBucket, srcName string, destBucket, destName string, gcs *storage.Client) (*storage.ObjectAttrs, error) {
-	src := gcs.Bucket(srcBucket).Object(srcName)
-	dst := gcs.Bucket(destBucket).Object(destName)
-	attrs, err := dst.CopierFrom(src).Run(ctx)
-	if err != nil {
-		var status *googleapi.Error
-		if errors.As(err, &status) {
-			if status.Code == http.StatusNotFound {
-				return nil, storagedriver.PathNotFoundError{Path: srcName}
-			}
-		}
-		return nil, fmt.Errorf("Object(%q).CopierFrom(%q).Run: %w", destName, srcName, err)
-	}
-	return attrs, err
-}
-
 // RedirectURL returns a URL which may be used to retrieve the content stored at
 // the given path, possibly using the given options.
 func (d *driver) RedirectURL(r *http.Request, path string) (string, error) {
@@ -826,7 +800,7 @@ func (d *driver) RedirectURL(r *http.Request, path string) (string, error) {
 		Method:         r.Method,
 		Expires:        time.Now().Add(20 * time.Minute),
 	}
-	return storage.SignedURL(d.bucket, d.pathToKey(path), opts)
+	return d.bucket.SignedURL(d.pathToKey(path), opts)
 }
 
 // Walk traverses a filesystem defined within driver, starting
@@ -835,21 +809,22 @@ func (d *driver) Walk(ctx context.Context, path string, f storagedriver.WalkFn,
 	return storagedriver.WalkFallback(ctx, d, path, f, options...)
 }
 
-func startSession(client *http.Client, bucket string, name string) (uri string, err error) {
+func (w *writer) newSession() (uri string, err error) {
 	u := &url.URL{
 		Scheme:   "https",
 		Host:     "www.googleapis.com",
-		Path:     fmt.Sprintf("/upload/storage/v1/b/%v/o", bucket),
+		Path:     fmt.Sprintf("/upload/storage/v1/b/%v/o", w.object.BucketName()),
-		RawQuery: fmt.Sprintf("uploadType=resumable&name=%v", name),
+		RawQuery: fmt.Sprintf("uploadType=resumable&name=%v", w.object.ObjectName()),
 	}
-	err = retry(func() error {
+	req, err := http.NewRequestWithContext(w.ctx, http.MethodPost, u.String(), nil)
-		req, err := http.NewRequest(http.MethodPost, u.String(), nil)
 	if err != nil {
-			return err
+		return "", err
 	}
-		req.Header.Set("X-Upload-Content-Type", "application/octet-stream")
+	req.Header.Set("X-Upload-Content-Type", blobContentType)
 	req.Header.Set("Content-Length", "0")
-		resp, err := client.Do(req)
+
+	err = retry(func() error {
+		resp, err := w.driver.client.Do(req)
 		if err != nil {
 			return err
 		}
@@ -864,12 +839,10 @@ func startSession(client *http.Client, bucket string, name string) (uri string,
 	return uri, err
 }
 
-func putChunk(client *http.Client, sessionURI string, chunk []byte, from int64, totalSize int64) (int64, error) {
+func (w *writer) putChunk(ctx context.Context, sessionURI string, chunk []byte, from int64, totalSize int64) (int64, error) {
-	bytesPut := int64(0)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPut, sessionURI, bytes.NewReader(chunk))
-	err := retry(func() error {
-		req, err := http.NewRequest(http.MethodPut, sessionURI, bytes.NewReader(chunk))
 	if err != nil {
-			return err
+		return 0, err
 	}
 	length := int64(len(chunk))
 	to := from + length - 1
@@ -877,20 +850,22 @@ func putChunk(client *http.Client, sessionURI string, chunk []byte, from int64,
 	if totalSize >= 0 {
 		size = strconv.FormatInt(totalSize, 10)
 	}
-		req.Header.Set("Content-Type", "application/octet-stream")
+	req.Header.Set("Content-Type", blobContentType)
 	if from == to+1 {
-			req.Header.Set("Content-Range", fmt.Sprintf("bytes */%v", size))
+		req.Header.Set("Content-Range", fmt.Sprintf("bytes */%s", size))
 	} else {
-			req.Header.Set("Content-Range", fmt.Sprintf("bytes %v-%v/%v", from, to, size))
+		req.Header.Set("Content-Range", fmt.Sprintf("bytes %d-%d/%s", from, to, size))
 	}
 	req.Header.Set("Content-Length", strconv.FormatInt(length, 10))
 
-		resp, err := client.Do(req)
+	bytesPut := int64(0)
+	err = retry(func() error {
+		resp, err := w.driver.client.Do(req)
 		if err != nil {
 			return err
 		}
 		defer resp.Body.Close()
-		if totalSize < 0 && resp.StatusCode == 308 {
+		if totalSize < 0 && resp.StatusCode == http.StatusPermanentRedirect {
 			groups := rangeHeader.FindStringSubmatch(resp.Header.Get("Range"))
 			end, err := strconv.ParseInt(groups[2], 10, 64)
 			if err != nil {