diff --git a/weed/mount/weedfs_file_copy_range.go b/weed/mount/weedfs_file_copy_range.go
index c85d5f9c4..0620b7dab 100644
--- a/weed/mount/weedfs_file_copy_range.go
+++ b/weed/mount/weedfs_file_copy_range.go
@@ -65,35 +65,15 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 		return 0, fuse.EISDIR
 	}
 
-	// cannot copy data to an overlapping range of the same file
-	offInEnd := in.OffIn + in.Len - 1
-	offOutEnd := in.OffOut + in.Len - 1
-
-	if fhIn.inode == fhOut.inode && in.OffIn <= offOutEnd && offInEnd >= in.OffOut {
-		return 0, fuse.EINVAL
-	}
-
 	glog.V(4).Infof(
-		"CopyFileRange %s fhIn %d -> %s fhOut %d, %d:%d -> %d:%d",
+		"CopyFileRange %s fhIn %d -> %s fhOut %d, [%d,%d) -> [%d,%d)",
 		fhIn.FullPath(), fhIn.fh,
 		fhOut.FullPath(), fhOut.fh,
-		in.OffIn, offInEnd,
-		in.OffOut, offOutEnd,
+		in.OffIn, in.OffIn+in.Len,
+		in.OffOut, in.OffOut+in.Len,
 	)
 
-	// read data from source file
-	fhIn.lockForRead(int64(in.OffIn), int(in.Len))
-	defer fhIn.unlockForRead(int64(in.OffIn), int(in.Len))
-
-	data := make([]byte, int(in.Len))
-	totalRead, err := fhIn.readFromChunks(data, int64(in.OffIn))
-	if err == nil || err == io.EOF {
-		maxStop := fhIn.readFromDirtyPages(data, int64(in.OffIn))
-		totalRead = max(maxStop-int64(in.OffIn), totalRead)
-	}
-	if err == io.EOF {
-		err = nil
-	}
+	data, totalRead, err := readDataByFileHandle(fhIn, in)
 	if err != nil {
 		glog.Warningf("file handle read %s %d: %v", fhIn.FullPath(), totalRead, err)
 		return 0, fuse.EIO
@@ -106,7 +86,7 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 	// put data at the specified offset in target file
 	fhOut.dirtyPages.writerPattern.MonitorWriteAt(int64(in.OffOut), int(in.Len))
 	fhOut.entry.Content = nil
-	fhOut.dirtyPages.AddPage(int64(in.OffOut), data, fhOut.dirtyPages.writerPattern.IsSequentialMode())
+	fhOut.dirtyPages.AddPage(int64(in.OffOut), data[:totalRead], fhOut.dirtyPages.writerPattern.IsSequentialMode())
 	fhOut.entry.Attributes.FileSize = uint64(max(int64(in.OffOut)+totalRead, int64(fhOut.entry.Attributes.FileSize)))
 	fhOut.dirtyMetadata = true
 	written = uint32(totalRead)
@@ -118,3 +98,20 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 
 	return written, fuse.OK
 }
+
+func readDataByFileHandle(fhIn *FileHandle, in *fuse.CopyFileRangeIn) ([]byte, int64, error) {
+	// read data from source file
+	fhIn.lockForRead(int64(in.OffIn), int(in.Len))
+	defer fhIn.unlockForRead(int64(in.OffIn), int(in.Len))
+
+	data := make([]byte, int(in.Len))
+	totalRead, err := fhIn.readFromChunks(data, int64(in.OffIn))
+	if err == nil || err == io.EOF {
+		maxStop := fhIn.readFromDirtyPages(data, int64(in.OffIn))
+		totalRead = max(maxStop-int64(in.OffIn), totalRead)
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	return data, totalRead, err
+}