b2: added disable sha1sum flag

backend/b2/b2.go

@@ -120,6 +120,11 @@ these chunks are buffered in memory and there might a maximum of
 minimim size.`,
 			Default:  fs.SizeSuffix(defaultChunkSize),
 			Advanced: true,
+		}, {
+			Name:     "disable_checksum",
+			Help:     `Disable checksums for large (> upload cutoff) files`,
+			Default:  false,
+			Advanced: true,
 		}},
 	})
 }
@@ -134,6 +139,7 @@ type Options struct {
 	HardDelete      bool          `config:"hard_delete"`
 	UploadCutoff    fs.SizeSuffix `config:"upload_cutoff"`
 	ChunkSize       fs.SizeSuffix `config:"chunk_size"`
+	DisableCheckSum bool          `config:"disable_checksum"`
 }
 
 // Fs represents a remote b2 server

backend/b2/upload.go

@@ -116,9 +116,11 @@ func (f *Fs) newLargeUpload(o *Object, in io.Reader, src fs.ObjectInfo) (up *lar
 		},
 	}
 	// Set the SHA1 if known
+	if !o.fs.opt.DisableCheckSum {
 		if calculatedSha1, err := src.Hash(hash.SHA1); err == nil && calculatedSha1 != "" {
 			request.Info[sha1Key] = calculatedSha1
 		}
+	}
 	var response api.StartLargeFileResponse
 	err = f.pacer.Call(func() (bool, error) {
 		resp, err := f.srv.CallJSON(&opts, &request, &response)