b2: Implement server side copy for files > 5GB - fixes #3991

This factors copy out of SetModTime and Copy so it can be called from
both places.

This also reworks all the multipart uploading to use sync.Errgroup and
memory pooling like the other backends. This makes it more memory
efficient and handle errors better.

See: https://forum.rclone.org/t/copying-files-within-a-b2-bucket/16680/10

backend/b2/api/types.go

@@ -337,3 +337,11 @@ type CopyFileRequest struct {
 	Info              map[string]string `json:"fileInfo,omitempty"`            // This field stores the metadata that will be stored with the file. (REPLACE only)
 	DestBucketID      string            `json:"destinationBucketId,omitempty"` // The destination ID of the bucket if set, if not the source bucket will be used
 }
+
+// CopyPartRequest is the request for b2_copy_part - the response is UploadPartResponse
+type CopyPartRequest struct {
+	SourceID    string `json:"sourceFileId"`    // The ID of the source file being copied.
+	LargeFileID string `json:"largeFileId"`     // The ID of the large file the part will belong to, as returned by b2_start_large_file.
+	PartNumber  int64  `json:"partNumber"`      // Which part this is (starting from 1)
+	Range       string `json:"range,omitempty"` // The range of bytes to copy. If not provided, the whole source file will be copied.
+}

backend/b2/b2.go

@@ -33,6 +33,7 @@ import (
 	"github.com/rclone/rclone/lib/bucket"
 	"github.com/rclone/rclone/lib/encoder"
 	"github.com/rclone/rclone/lib/pacer"
+	"github.com/rclone/rclone/lib/pool"
 	"github.com/rclone/rclone/lib/rest"
 )
 
@@ -54,6 +55,9 @@ const (
 	minChunkSize        = 5 * fs.MebiByte
 	defaultChunkSize    = 96 * fs.MebiByte
 	defaultUploadCutoff = 200 * fs.MebiByte
+	largeFileCopyCutoff = 4 * fs.GibiByte          // 5E9 is the max
+	memoryPoolFlushTime = fs.Duration(time.Minute) // flush the cached buffers after this long
+	memoryPoolUseMmap   = false
 )
 
 // Globals
@@ -113,6 +117,16 @@ Files above this size will be uploaded in chunks of "--b2-chunk-size".
 This value should be set no larger than 4.657GiB (== 5GB).`,
 			Default:  defaultUploadCutoff,
 			Advanced: true,
+		}, {
+			Name: "copy_cutoff",
+			Help: `Cutoff for switching to multipart copy
+
+Any files larger than this that need to be server side copied will be
+copied in chunks of this size.
+
+The minimum is 0 and the maximum is 4.6GB.`,
+			Default:  largeFileCopyCutoff,
+			Advanced: true,
 		}, {
 			Name: "chunk_size",
 			Help: `Upload chunk size. Must fit in memory.
@@ -150,6 +164,18 @@ The duration before the download authorization token will expire.
 The minimum value is 1 second. The maximum value is one week.`,
 			Default:  fs.Duration(7 * 24 * time.Hour),
 			Advanced: true,
+		}, {
+			Name:     "memory_pool_flush_time",
+			Default:  memoryPoolFlushTime,
+			Advanced: true,
+			Help: `How often internal memory buffer pools will be flushed.
+Uploads which requires additional buffers (f.e multipart) will use memory pool for allocations.
+This option controls how often unused buffers will be removed from the pool.`,
+		}, {
+			Name:     "memory_pool_use_mmap",
+			Default:  memoryPoolUseMmap,
+			Advanced: true,
+			Help:     `Whether to use mmap buffers in internal memory pool.`,
 		}, {
 			Name:     config.ConfigEncoding,
 			Help:     config.ConfigEncodingHelp,
@@ -173,10 +199,13 @@ type Options struct {
 	Versions                      bool                 `config:"versions"`
 	HardDelete                    bool                 `config:"hard_delete"`
 	UploadCutoff                  fs.SizeSuffix        `config:"upload_cutoff"`
+	CopyCutoff                    fs.SizeSuffix        `config:"copy_cutoff"`
 	ChunkSize                     fs.SizeSuffix        `config:"chunk_size"`
 	DisableCheckSum               bool                 `config:"disable_checksum"`
 	DownloadURL                   string               `config:"download_url"`
 	DownloadAuthorizationDuration fs.Duration          `config:"download_auth_duration"`
+	MemoryPoolFlushTime           fs.Duration          `config:"memory_pool_flush_time"`
+	MemoryPoolUseMmap             bool                 `config:"memory_pool_use_mmap"`
 	Enc                           encoder.MultiEncoder `config:"encoding"`
 }
 
@@ -199,7 +228,8 @@ type Fs struct {
 	uploads         map[string][]*api.GetUploadURLResponse // Upload URLs by buckedID
 	authMu          sync.Mutex                             // lock for authorizing the account
 	pacer           *fs.Pacer                              // To pace and retry the API calls
-	bufferTokens    chan []byte                            // control concurrency of multipart uploads
+	uploadToken     *pacer.TokenDispenser                  // control concurrency
+	pool            *pool.Pool                             // memory pool
 }
 
 // Object describes a b2 object
@@ -335,7 +365,6 @@ func (f *Fs) setUploadChunkSize(cs fs.SizeSuffix) (old fs.SizeSuffix, err error)
 	err = checkUploadChunkSize(cs)
 	if err == nil {
 		old, f.opt.ChunkSize = f.opt.ChunkSize, cs
-		f.fillBufferTokens() // reset the buffer tokens
 	}
 	return
 }
@@ -396,6 +425,13 @@ func NewFs(name, root string, m configmap.Mapper) (fs.Fs, error) {
 		_bucketType: make(map[string]string, 1),
 		uploads:     make(map[string][]*api.GetUploadURLResponse),
 		pacer:       fs.NewPacer(pacer.NewDefault(pacer.MinSleep(minSleep), pacer.MaxSleep(maxSleep), pacer.DecayConstant(decayConstant))),
+		uploadToken: pacer.NewTokenDispenser(fs.Config.Transfers),
+		pool: pool.New(
+			time.Duration(opt.MemoryPoolFlushTime),
+			int(opt.ChunkSize),
+			fs.Config.Transfers,
+			opt.MemoryPoolUseMmap,
+		),
 	}
 	f.setRoot(root)
 	f.features = (&fs.Features{
@@ -410,7 +446,6 @@ func NewFs(name, root string, m configmap.Mapper) (fs.Fs, error) {
 		f.srv.SetHeader(testModeHeader, testMode)
 		fs.Debugf(f, "Setting test header \"%s: %s\"", testModeHeader, testMode)
 	}
-	f.fillBufferTokens()
 	err = f.authorizeAccount(ctx)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to authorize account")
@@ -533,32 +568,25 @@ func (f *Fs) clearUploadURL(bucketID string) {
 	f.uploadMu.Unlock()
 }
 
-// Fill up (or reset) the buffer tokens
+// getBuf gets a buffer of f.opt.ChunkSize and an upload token
-func (f *Fs) fillBufferTokens() {
+//
-	f.bufferTokens = make(chan []byte, fs.Config.Transfers)
+// If noBuf is set then it just gets an upload token
-	for i := 0; i < fs.Config.Transfers; i++ {
+func (f *Fs) getBuf(noBuf bool) (buf []byte) {
-		f.bufferTokens <- nil
+	f.uploadToken.Get()
+	if !noBuf {
+		buf = f.pool.Get()
 	}
-}
-
-// getUploadBlock gets a block from the pool of size chunkSize
-func (f *Fs) getUploadBlock() []byte {
-	buf := <-f.bufferTokens
-	if buf == nil {
-		buf = make([]byte, f.opt.ChunkSize)
-	}
-	// fs.Debugf(f, "Getting upload block %p", buf)
 	return buf
 }
 
-// putUploadBlock returns a block to the pool of size chunkSize
+// putBuf returns a buffer to the memory pool and an upload token
-func (f *Fs) putUploadBlock(buf []byte) {
+//
-	buf = buf[:cap(buf)]
+// If noBuf is set then it just returns the upload token
-	if len(buf) != int(f.opt.ChunkSize) {
+func (f *Fs) putBuf(buf []byte, noBuf bool) {
-		panic("bad blocksize returned to pool")
+	if !noBuf {
+		f.pool.Put(buf)
 	}
-	// fs.Debugf(f, "Returning upload block %p", buf)
+	f.uploadToken.Put()
-	f.bufferTokens <- buf
 }
 
 // Return an Object from a path
@@ -1205,6 +1233,63 @@ func (f *Fs) CleanUp(ctx context.Context) error {
 	return f.purge(ctx, f.rootBucket, f.rootDirectory, true)
 }
 
+// copy does a server side copy from dstObj <- srcObj
+//
+// If newInfo is nil then the metadata will be copied otherwise it
+// will be replaced with newInfo
+func (f *Fs) copy(ctx context.Context, dstObj *Object, srcObj *Object, newInfo *api.File) (err error) {
+	if srcObj.size >= int64(f.opt.CopyCutoff) {
+		if newInfo == nil {
+			newInfo, err = srcObj.getMetaData(ctx)
+			if err != nil {
+				return err
+			}
+		}
+		up, err := f.newLargeUpload(ctx, dstObj, nil, srcObj, f.opt.CopyCutoff, true, newInfo)
+		if err != nil {
+			return err
+		}
+		return up.Upload(ctx)
+	}
+
+	dstBucket, dstPath := dstObj.split()
+	err = f.makeBucket(ctx, dstBucket)
+	if err != nil {
+		return err
+	}
+
+	destBucketID, err := f.getBucketID(ctx, dstBucket)
+	if err != nil {
+		return err
+	}
+
+	opts := rest.Opts{
+		Method: "POST",
+		Path:   "/b2_copy_file",
+	}
+	var request = api.CopyFileRequest{
+		SourceID:     srcObj.id,
+		Name:         f.opt.Enc.FromStandardPath(dstPath),
+		DestBucketID: destBucketID,
+	}
+	if newInfo == nil {
+		request.MetadataDirective = "COPY"
+	} else {
+		request.MetadataDirective = "REPLACE"
+		request.ContentType = newInfo.ContentType
+		request.Info = newInfo.Info
+	}
+	var response api.FileInfo
+	err = f.pacer.Call(func() (bool, error) {
+		resp, err := f.srv.CallJSON(ctx, &opts, &request, &response)
+		return f.shouldRetry(ctx, resp, err)
+	})
+	if err != nil {
+		return err
+	}
+	return dstObj.decodeMetaDataFileInfo(&response)
+}
+
 // Copy src to this remote using server side copy operations.
 //
 // This is stored with the remote path given
@@ -1215,47 +1300,21 @@ func (f *Fs) CleanUp(ctx context.Context) error {
 //
 // If it isn't possible then return fs.ErrorCantCopy
 func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object, error) {
-	dstBucket, dstPath := f.split(remote)
-	err := f.makeBucket(ctx, dstBucket)
-	if err != nil {
-		return nil, err
-	}
 	srcObj, ok := src.(*Object)
 	if !ok {
 		fs.Debugf(src, "Can't copy - not same remote type")
 		return nil, fs.ErrorCantCopy
 	}
-	destBucketID, err := f.getBucketID(ctx, dstBucket)
+	// Temporary Object under construction
-	if err != nil {
+	dstObj := &Object{
-		return nil, err
-	}
-	opts := rest.Opts{
-		Method: "POST",
-		Path:   "/b2_copy_file",
-	}
-	var request = api.CopyFileRequest{
-		SourceID:          srcObj.id,
-		Name:              f.opt.Enc.FromStandardPath(dstPath),
-		MetadataDirective: "COPY",
-		DestBucketID:      destBucketID,
-	}
-	var response api.FileInfo
-	err = f.pacer.Call(func() (bool, error) {
-		resp, err := f.srv.CallJSON(ctx, &opts, &request, &response)
-		return f.shouldRetry(ctx, resp, err)
-	})
-	if err != nil {
-		return nil, err
-	}
-	o := &Object{
 		fs:     f,
 		remote: remote,
 	}
-	err = o.decodeMetaDataFileInfo(&response)
+	err := f.copy(ctx, dstObj, srcObj, nil)
 	if err != nil {
 		return nil, err
 	}
-	return o, nil
+	return dstObj, nil
 }
 
 // Hashes returns the supported hash sets.
@@ -1526,28 +1585,10 @@ func (o *Object) SetModTime(ctx context.Context, modTime time.Time) error {
 	if err != nil {
 		return err
 	}
-	_, bucketPath := o.split()
 	info.Info[timeKey] = timeString(modTime)
-	opts := rest.Opts{
+
-		Method: "POST",
+	// Copy to the same name, overwriting the metadata only
-		Path:   "/b2_copy_file",
+	return o.fs.copy(ctx, o, o, info)
-	}
-	var request = api.CopyFileRequest{
-		SourceID:          o.id,
-		Name:              o.fs.opt.Enc.FromStandardPath(bucketPath), // copy to same name
-		MetadataDirective: "REPLACE",
-		ContentType:       info.ContentType,
-		Info:              info.Info,
-	}
-	var response api.FileInfo
-	err = o.fs.pacer.Call(func() (bool, error) {
-		resp, err := o.fs.srv.CallJSON(ctx, &opts, &request, &response)
-		return o.fs.shouldRetry(ctx, resp, err)
-	})
-	if err != nil {
-		return err
-	}
-	return o.decodeMetaDataFileInfo(&response)
 }
 
 // Storable returns if this object is storable
@@ -1723,7 +1764,8 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	}
 	if size == -1 {
 		// Check if the file is large enough for a chunked upload (needs to be at least two chunks)
-		buf := o.fs.getUploadBlock()
+		buf := o.fs.getBuf(false)
+
 		n, err := io.ReadFull(in, buf)
 		if err == nil {
 			bufReader := bufio.NewReader(in)
@@ -1733,22 +1775,24 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 
 		if err == nil {
 			fs.Debugf(o, "File is big enough for chunked streaming")
-			up, err := o.fs.newLargeUpload(ctx, o, in, src)
+			up, err := o.fs.newLargeUpload(ctx, o, in, src, o.fs.opt.ChunkSize, false, nil)
 			if err != nil {
-				o.fs.putUploadBlock(buf)
+				o.fs.putBuf(buf, false)
 				return err
 			}
+			// NB Stream returns the buffer and token
 			return up.Stream(ctx, buf)
 		} else if err == io.EOF || err == io.ErrUnexpectedEOF {
 			fs.Debugf(o, "File has %d bytes, which makes only one chunk. Using direct upload.", n)
-			defer o.fs.putUploadBlock(buf)
+			defer o.fs.putBuf(buf, false)
 			size = int64(n)
 			in = bytes.NewReader(buf[:n])
 		} else {
+			o.fs.putBuf(buf, false)
 			return err
 		}
 	} else if size > int64(o.fs.opt.UploadCutoff) {
-		up, err := o.fs.newLargeUpload(ctx, o, in, src)
+		up, err := o.fs.newLargeUpload(ctx, o, in, src, o.fs.opt.ChunkSize, false, nil)
 		if err != nil {
 			return err
 		}

backend/b2/upload.go

@@ -21,6 +21,7 @@ import (
 	"github.com/rclone/rclone/fs/accounting"
 	"github.com/rclone/rclone/fs/hash"
 	"github.com/rclone/rclone/lib/rest"
+	"golang.org/x/sync/errgroup"
 )
 
 type hashAppendingReader struct {
@@ -68,20 +69,26 @@ func newHashAppendingReader(in io.Reader, h gohash.Hash) *hashAppendingReader {
 
 // largeUpload is used to control the upload of large files which need chunking
 type largeUpload struct {
-	f        *Fs                             // parent Fs
+	f         *Fs                             // parent Fs
-	o        *Object                         // object being uploaded
+	o         *Object                         // object being uploaded
-	in       io.Reader                       // read the data from here
+	doCopy    bool                            // doing copy rather than upload
-	wrap     accounting.WrapFn               // account parts being transferred
+	what      string                          // text name of operation for logs
-	id       string                          // ID of the file being uploaded
+	in        io.Reader                       // read the data from here
-	size     int64                           // total size
+	wrap      accounting.WrapFn               // account parts being transferred
-	parts    int64                           // calculated number of parts, if known
+	id        string                          // ID of the file being uploaded
-	sha1s    []string                        // slice of SHA1s for each part
+	size      int64                           // total size
-	uploadMu sync.Mutex                      // lock for upload variable
+	parts     int64                           // calculated number of parts, if known
-	uploads  []*api.GetUploadPartURLResponse // result of get upload URL calls
+	sha1s     []string                        // slice of SHA1s for each part
+	uploadMu  sync.Mutex                      // lock for upload variable
+	uploads   []*api.GetUploadPartURLResponse // result of get upload URL calls
+	chunkSize int64                           // chunk size to use
+	src       *Object                         // if copying, object we are reading from
 }
 
 // newLargeUpload starts an upload of object o from in with metadata in src
-func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs.ObjectInfo) (up *largeUpload, err error) {
+//
+// If newInfo is set then metadata from that will be used instead of reading it from src
+func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs.ObjectInfo, chunkSize fs.SizeSuffix, doCopy bool, newInfo *api.File) (up *largeUpload, err error) {
 	remote := o.remote
 	size := src.Size()
 	parts := int64(0)
@@ -89,8 +96,8 @@ func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs
 	if size == -1 {
 		fs.Debugf(o, "Streaming upload with --b2-chunk-size %s allows uploads of up to %s and will fail only when that limit is reached.", f.opt.ChunkSize, maxParts*f.opt.ChunkSize)
 	} else {
-		parts = size / int64(o.fs.opt.ChunkSize)
+		parts = size / int64(chunkSize)
-		if size%int64(o.fs.opt.ChunkSize) != 0 {
+		if size%int64(chunkSize) != 0 {
 			parts++
 		}
 		if parts > maxParts {
@@ -99,7 +106,6 @@ func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs
 		sha1SliceSize = parts
 	}
 
-	modTime := src.ModTime(ctx)
 	opts := rest.Opts{
 		Method: "POST",
 		Path:   "/b2_start_large_file",
@@ -110,18 +116,24 @@ func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs
 		return nil, err
 	}
 	var request = api.StartLargeFileRequest{
-		BucketID:    bucketID,
+		BucketID: bucketID,
-		Name:        f.opt.Enc.FromStandardPath(bucketPath),
+		Name:     f.opt.Enc.FromStandardPath(bucketPath),
-		ContentType: fs.MimeType(ctx, src),
-		Info: map[string]string{
-			timeKey: timeString(modTime),
-		},
 	}
-	// Set the SHA1 if known
+	if newInfo == nil {
-	if !o.fs.opt.DisableCheckSum {
+		modTime := src.ModTime(ctx)
-		if calculatedSha1, err := src.Hash(ctx, hash.SHA1); err == nil && calculatedSha1 != "" {
+		request.ContentType = fs.MimeType(ctx, src)
-			request.Info[sha1Key] = calculatedSha1
+		request.Info = map[string]string{
+			timeKey: timeString(modTime),
 		}
+		// Set the SHA1 if known
+		if !o.fs.opt.DisableCheckSum || doCopy {
+			if calculatedSha1, err := src.Hash(ctx, hash.SHA1); err == nil && calculatedSha1 != "" {
+				request.Info[sha1Key] = calculatedSha1
+			}
+		}
+	} else {
+		request.ContentType = newInfo.ContentType
+		request.Info = newInfo.Info
 	}
 	var response api.StartLargeFileResponse
 	err = f.pacer.Call(func() (bool, error) {
@@ -131,18 +143,24 @@ func (f *Fs) newLargeUpload(ctx context.Context, o *Object, in io.Reader, src fs
 	if err != nil {
 		return nil, err
 	}
+	up = &largeUpload{
+		f:         f,
+		o:         o,
+		doCopy:    doCopy,
+		what:      "upload",
+		id:        response.ID,
+		size:      size,
+		parts:     parts,
+		sha1s:     make([]string, sha1SliceSize),
+		chunkSize: int64(chunkSize),
+	}
 	// unwrap the accounting from the input, we use wrap to put it
 	// back on after the buffering
-	in, wrap := accounting.UnWrap(in)
+	if doCopy {
-	up = &largeUpload{
+		up.what = "copy"
-		f:     f,
+		up.src = src.(*Object)
-		o:     o,
+	} else {
-		in:    in,
+		up.in, up.wrap = accounting.UnWrap(in)
-		wrap:  wrap,
-		id:    response.ID,
-		size:  size,
-		parts: parts,
-		sha1s: make([]string, sha1SliceSize),
 	}
 	return up, nil
 }
@@ -256,9 +274,41 @@ func (up *largeUpload) transferChunk(ctx context.Context, part int64, body []byt
 	return err
 }
 
+// Copy a chunk
+func (up *largeUpload) copyChunk(ctx context.Context, part int64, partSize int64) error {
+	err := up.f.pacer.Call(func() (bool, error) {
+		fs.Debugf(up.o, "Copying chunk %d length %d", part, partSize)
+		opts := rest.Opts{
+			Method: "POST",
+			Path:   "/b2_copy_part",
+		}
+		offset := (part - 1) * up.chunkSize // where we are in the source file
+		var request = api.CopyPartRequest{
+			SourceID:    up.src.id,
+			LargeFileID: up.id,
+			PartNumber:  part,
+			Range:       fmt.Sprintf("bytes=%d-%d", offset, offset+partSize-1),
+		}
+		var response api.UploadPartResponse
+		resp, err := up.f.srv.CallJSON(ctx, &opts, &request, &response)
+		retry, err := up.f.shouldRetry(ctx, resp, err)
+		if err != nil {
+			fs.Debugf(up.o, "Error copying chunk %d (retry=%v): %v: %#v", part, retry, err, err)
+		}
+		up.sha1s[part-1] = response.SHA1
+		return retry, err
+	})
+	if err != nil {
+		fs.Debugf(up.o, "Error copying chunk %d: %v", part, err)
+	} else {
+		fs.Debugf(up.o, "Done copying chunk %d", part)
+	}
+	return err
+}
+
 // finish closes off the large upload
 func (up *largeUpload) finish(ctx context.Context) error {
-	fs.Debugf(up.o, "Finishing large file upload with %d parts", up.parts)
+	fs.Debugf(up.o, "Finishing large file %s with %d parts", up.what, up.parts)
 	opts := rest.Opts{
 		Method: "POST",
 		Path:   "/b2_finish_large_file",
@@ -295,136 +345,145 @@ func (up *largeUpload) cancel(ctx context.Context) error {
 	return err
 }
 
-func (up *largeUpload) managedTransferChunk(ctx context.Context, wg *sync.WaitGroup, errs chan error, part int64, buf []byte) {
+// If the error pointer is not nil then cancel the transfer
-	wg.Add(1)
+func (up *largeUpload) cancelOnError(ctx context.Context, err *error) {
-	go func(part int64, buf []byte) {
+	if *err == nil {
-		defer wg.Done()
+		return
-		defer up.f.putUploadBlock(buf)
-		err := up.transferChunk(ctx, part, buf)
-		if err != nil {
-			select {
-			case errs <- err:
-			default:
-			}
-		}
-	}(part, buf)
-}
-
-func (up *largeUpload) finishOrCancelOnError(ctx context.Context, err error, errs chan error) error {
-	if err == nil {
-		select {
-		case err = <-errs:
-		default:
-		}
 	}
-	if err != nil {
+	fs.Debugf(up.o, "Cancelling large file %s due to error: %v", up.what, *err)
-		fs.Debugf(up.o, "Cancelling large file upload due to error: %v", err)
+	cancelErr := up.cancel(ctx)
-		cancelErr := up.cancel(ctx)
+	if cancelErr != nil {
-		if cancelErr != nil {
+		fs.Errorf(up.o, "Failed to cancel large file %s: %v", up.what, cancelErr)
-			fs.Errorf(up.o, "Failed to cancel large file upload: %v", cancelErr)
-		}
-		return err
 	}
-	return up.finish(ctx)
 }
 
 // Stream uploads the chunks from the input, starting with a required initial
 // chunk. Assumes the file size is unknown and will upload until the input
 // reaches EOF.
+//
+// Note that initialUploadBlock must be returned to f.putBuf()
 func (up *largeUpload) Stream(ctx context.Context, initialUploadBlock []byte) (err error) {
+	defer up.cancelOnError(ctx, &err)
 	fs.Debugf(up.o, "Starting streaming of large file (id %q)", up.id)
-	errs := make(chan error, 1)
+	var (
-	hasMoreParts := true
+		g, gCtx      = errgroup.WithContext(ctx)
-	var wg sync.WaitGroup
+		hasMoreParts = true
-
+	)
-	// Transfer initial chunk
 	up.size = int64(len(initialUploadBlock))
-	up.managedTransferChunk(ctx, &wg, errs, 1, initialUploadBlock)
+	g.Go(func() error {
+		for part := int64(1); hasMoreParts; part++ {
+			// Get a block of memory from the pool and token which limits concurrency.
+			var buf []byte
+			if part == 1 {
+				buf = initialUploadBlock
+			} else {
+				buf = up.f.getBuf(false)
+			}
 
-outer:
+			// Fail fast, in case an errgroup managed function returns an error
-	for part := int64(2); hasMoreParts; part++ {
+			// gCtx is cancelled. There is no point in uploading all the other parts.
-		// Check any errors
+			if gCtx.Err() != nil {
-		select {
+				up.f.putBuf(buf, false)
-		case err = <-errs:
+				return nil
-			break outer
+			}
-		default:
+
+			// Read the chunk
+			var n int
+			if part == 1 {
+				n = len(buf)
+			} else {
+				n, err = io.ReadFull(up.in, buf)
+				if err == io.ErrUnexpectedEOF {
+					fs.Debugf(up.o, "Read less than a full chunk, making this the last one.")
+					buf = buf[:n]
+					hasMoreParts = false
+				} else if err == io.EOF {
+					fs.Debugf(up.o, "Could not read any more bytes, previous chunk was the last.")
+					up.f.putBuf(buf, false)
+					return nil
+				} else if err != nil {
+					// other kinds of errors indicate failure
+					up.f.putBuf(buf, false)
+					return err
+				}
+			}
+
+			// Keep stats up to date
+			up.parts = part
+			up.size += int64(n)
+			if part > maxParts {
+				up.f.putBuf(buf, false)
+				return errors.Errorf("%q too big (%d bytes so far) makes too many parts %d > %d - increase --b2-chunk-size", up.o, up.size, up.parts, maxParts)
+			}
+
+			part := part // for the closure
+			g.Go(func() (err error) {
+				defer up.f.putBuf(buf, false)
+				return up.transferChunk(gCtx, part, buf)
+			})
 		}
-
+		return nil
-		// Get a block of memory
+	})
-		buf := up.f.getUploadBlock()
+	err = g.Wait()
-
+	if err != nil {
-		// Read the chunk
+		return err
-		var n int
-		n, err = io.ReadFull(up.in, buf)
-		if err == io.ErrUnexpectedEOF {
-			fs.Debugf(up.o, "Read less than a full chunk, making this the last one.")
-			buf = buf[:n]
-			hasMoreParts = false
-			err = nil
-		} else if err == io.EOF {
-			fs.Debugf(up.o, "Could not read any more bytes, previous chunk was the last.")
-			up.f.putUploadBlock(buf)
-			err = nil
-			break outer
-		} else if err != nil {
-			// other kinds of errors indicate failure
-			up.f.putUploadBlock(buf)
-			break outer
-		}
-
-		// Keep stats up to date
-		up.parts = part
-		up.size += int64(n)
-		if part > maxParts {
-			err = errors.Errorf("%q too big (%d bytes so far) makes too many parts %d > %d - increase --b2-chunk-size", up.o, up.size, up.parts, maxParts)
-			break outer
-		}
-
-		// Transfer the chunk
-		up.managedTransferChunk(ctx, &wg, errs, part, buf)
 	}
-	wg.Wait()
 	up.sha1s = up.sha1s[:up.parts]
-
+	return up.finish(ctx)
-	return up.finishOrCancelOnError(ctx, err, errs)
 }
 
 // Upload uploads the chunks from the input
-func (up *largeUpload) Upload(ctx context.Context) error {
+func (up *largeUpload) Upload(ctx context.Context) (err error) {
-	fs.Debugf(up.o, "Starting upload of large file in %d chunks (id %q)", up.parts, up.id)
+	defer up.cancelOnError(ctx, &err)
-	remaining := up.size
+	fs.Debugf(up.o, "Starting %s of large file in %d chunks (id %q)", up.what, up.parts, up.id)
-	errs := make(chan error, 1)
+	var (
-	var wg sync.WaitGroup
+		g, gCtx   = errgroup.WithContext(ctx)
-	var err error
+		remaining = up.size
-outer:
+	)
-	for part := int64(1); part <= up.parts; part++ {
+	g.Go(func() error {
-		// Check any errors
+		for part := int64(1); part <= up.parts; part++ {
-		select {
+			// Get a block of memory from the pool and token which limits concurrency.
-		case err = <-errs:
+			buf := up.f.getBuf(up.doCopy)
-			break outer
+
-		default:
+			// Fail fast, in case an errgroup managed function returns an error
+			// gCtx is cancelled. There is no point in uploading all the other parts.
+			if gCtx.Err() != nil {
+				up.f.putBuf(buf, up.doCopy)
+				return nil
+			}
+
+			reqSize := remaining
+			if reqSize >= up.chunkSize {
+				reqSize = up.chunkSize
+			}
+
+			if !up.doCopy {
+				// Read the chunk
+				buf = buf[:reqSize]
+				_, err = io.ReadFull(up.in, buf)
+				if err != nil {
+					up.f.putBuf(buf, up.doCopy)
+					return err
+				}
+			}
+
+			part := part // for the closure
+			g.Go(func() (err error) {
+				defer up.f.putBuf(buf, up.doCopy)
+				if !up.doCopy {
+					err = up.transferChunk(gCtx, part, buf)
+				} else {
+					err = up.copyChunk(gCtx, part, reqSize)
+				}
+				return err
+			})
+			remaining -= reqSize
 		}
-
+		return nil
-		reqSize := remaining
+	})
-		if reqSize >= int64(up.f.opt.ChunkSize) {
+	err = g.Wait()
-			reqSize = int64(up.f.opt.ChunkSize)
+	if err != nil {
-		}
+		return err
-
-		// Get a block of memory
-		buf := up.f.getUploadBlock()[:reqSize]
-
-		// Read the chunk
-		_, err = io.ReadFull(up.in, buf)
-		if err != nil {
-			up.f.putUploadBlock(buf)
-			break outer
-		}
-
-		// Transfer the chunk
-		up.managedTransferChunk(ctx, &wg, errs, part, buf)
-		remaining -= reqSize
 	}
-	wg.Wait()
+	return up.finish(ctx)
-
-	return up.finishOrCancelOnError(ctx, err, errs)
 }