onedrive: re-add --onedrive-upload-cutoff flag

This was removed as part of #1716 to fix rclone uploads taking double
the space.

7f744033d8eae0fa onedrive: Removed upload cutoff and always do session uploads

As far as I can see, two revisions are still being created for single
part uploads so the default for this flag is set to -1, off.

However it may be useful for experimentation.

See: #8545

backend/onedrive/onedrive.go

@@ -56,6 +56,7 @@ const (
 	driveTypeSharepoint         = "documentLibrary"
 	defaultChunkSize            = 10 * fs.Mebi
 	chunkSizeMultiple           = 320 * fs.Kibi
+	maxSinglePartSize           = 4 * fs.Mebi
 
 	regionGlobal = "global"
 	regionUS     = "us"
@@ -138,6 +139,21 @@ func init() {
 					Help:  "Azure and Office 365 operated by Vnet Group in China",
 				},
 			},
+		}, {
+			Name: "upload_cutoff",
+			Help: `Cutoff for switching to chunked upload.
+
+Any files larger than this will be uploaded in chunks of chunk_size.
+
+This is disabled by default as uploading using single part uploads
+causes rclone to use twice the storage on Onedrive business as when
+rclone sets the modification time after the upload Onedrive creates a
+new version.
+
+See: https://github.com/rclone/rclone/issues/1716
+`,
+			Default:  fs.SizeSuffix(-1),
+			Advanced: true,
 		}, {
 			Name: "chunk_size",
 			Help: `Chunk size to upload files with - must be multiple of 320k (327,680 bytes).
@@ -746,6 +762,7 @@ Examples:
 // Options defines the configuration for this backend
 type Options struct {
 	Region                  string               `config:"region"`
+	UploadCutoff            fs.SizeSuffix        `config:"upload_cutoff"`
 	ChunkSize               fs.SizeSuffix        `config:"chunk_size"`
 	DriveID                 string               `config:"drive_id"`
 	DriveType               string               `config:"drive_type"`
@@ -1022,6 +1039,13 @@ func (f *Fs) setUploadChunkSize(cs fs.SizeSuffix) (old fs.SizeSuffix, err error)
 	return
 }
 
+func checkUploadCutoff(cs fs.SizeSuffix) error {
+	if cs > maxSinglePartSize {
+		return fmt.Errorf("%v is greater than %v", cs, maxSinglePartSize)
+	}
+	return nil
+}
+
 // NewFs constructs an Fs from the path, container:path
 func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, error) {
 	// Parse config into Options struct
@@ -1035,6 +1059,10 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	if err != nil {
 		return nil, fmt.Errorf("onedrive: chunk size: %w", err)
 	}
+	err = checkUploadCutoff(opt.UploadCutoff)
+	if err != nil {
+		return nil, fmt.Errorf("onedrive: upload cutoff: %w", err)
+	}
 
 	if opt.DriveID == "" || opt.DriveType == "" {
 		return nil, errors.New("unable to get drive_id and drive_type - if you are upgrading from older versions of rclone, please run `rclone config` and re-configure this backend")
@@ -2567,8 +2595,8 @@ func (o *Object) uploadMultipart(ctx context.Context, in io.Reader, src fs.Objec
 // This function will set modtime and metadata after uploading, which will create a new version for the remote file
 func (o *Object) uploadSinglepart(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (info *api.Item, err error) {
 	size := src.Size()
-	if size < 0 || size > int64(fs.SizeSuffix(4*1024*1024)) {
+	if size < 0 || size > int64(maxSinglePartSize) {
-		return nil, errors.New("size passed into uploadSinglepart must be >= 0 and <= 4 MiB")
+		return nil, fmt.Errorf("size passed into uploadSinglepart must be >= 0 and <= %v", maxSinglePartSize)
 	}
 
 	fs.Debugf(o, "Starting singlepart upload")
@@ -2621,9 +2649,9 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	size := src.Size()
 
 	var info *api.Item
-	if size > 0 {
+	if size > 0 && size >= int64(o.fs.opt.UploadCutoff) {
 		info, err = o.uploadMultipart(ctx, in, src, options...)
-	} else if size == 0 {
+	} else if size >= 0 {
 		info, err = o.uploadSinglepart(ctx, in, src, options...)
 	} else {
 		return errors.New("unknown-sized upload not supported")