local: add --local-no-check-updated to disable update checks #2206

This disables the `can't copy - source file is being updated` checks.

backend/local/local.go

@@ -28,6 +28,7 @@ var (
 	followSymlinks = flags.BoolP("copy-links", "L", false, "Follow symlinks and copy the pointed to item.")
 	skipSymlinks   = flags.BoolP("skip-links", "", false, "Don't warn about skipped symlinks.")
 	noUTFNorm      = flags.BoolP("local-no-unicode-normalization", "", false, "Don't apply unicode normalization to paths and filenames")
+	noCheckUpdated = flags.BoolP("local-no-check-updated", "", false, "Don't check to see if the files change during upload")
 )
 
 // Constants
@@ -673,6 +674,7 @@ type localOpenFile struct {
 
 // Read bytes from the object - see io.Reader
 func (file *localOpenFile) Read(p []byte) (n int, err error) {
+	if !*noCheckUpdated {
 		// Check if file has the same size and modTime
 		fi, err := file.fd.Stat()
 		if err != nil {
@@ -684,6 +686,7 @@ func (file *localOpenFile) Read(p []byte) (n int, err error) {
 		if !file.o.modTime.Equal(fi.ModTime()) {
 			return 0, errors.Errorf("can't copy - source file is being updated (mod time changed from %v to %v)", file.o.modTime, fi.ModTime())
 		}
+	}
 
 	n, err = file.in.Read(p)
 	if n > 0 {

backend/local/local_internal_test.go

@@ -29,8 +29,10 @@ func TestMapper(t *testing.T) {
 	})
 	assert.Equal(t, "potato", m.Load("potato"))
 	assert.Equal(t, "-r?'a´o¨", m.Load("-r'áö"))
+}
 
-	// Test copy with source file that's updating
+// Test copy with source file that's updating
+func TestUpdatingCheck(t *testing.T) {
 	r := fstest.NewRun(t)
 	defer r.Finalise()
 	filePath := "sub dir/local test"
@@ -59,4 +61,16 @@ func TestMapper(t *testing.T) {
 	r.WriteFile(filePath, "content updated", time.Now())
 	_, err = in.Read(buf)
 	require.Errorf(t, err, "can't copy - source file is being updated")
+
+	// turn the checking off and try again
+
+	*noCheckUpdated = true
+	defer func() {
+		*noCheckUpdated = false
+	}()
+
+	r.WriteFile(filePath, "content updated", time.Now())
+	_, err = in.Read(buf)
+	require.NoError(t, err)
+
 }

docs/content/local.md

@@ -120,6 +120,18 @@ $ rclone -L ls /tmp/a
         6 b/one
 ```
 
+#### --local-no-check-updated ####
+
+Don't check to see if the files change during upload.
+
+Normally rclone checks the size and modification time of files as they
+are being uploaded and aborts with a message which starts `can't copy
+- source file is being updated` if the file changes during upload.
+
+However on some file systems this modification time check may fail (eg
+[Glusterfs #2206](https://github.com/ncw/rclone/issues/2206)) so this
+check can be disabled with this flag.
+
 #### --local-no-unicode-normalization ####
 
 This flag is deprecated now.  Rclone no longer normalizes unicode file