From f5989a21fb7c550a0a014a52bd664b10ecc3850d Mon Sep 17 00:00:00 2001
From: Nicholas Oh <nicholas@nitrous.dev>
Date: Sat, 31 Oct 2026 20:28:54 +0800
Subject: [PATCH] s3: honor assignment fsync in streaming copies (#12277)

---
 .../s3api_object_handlers_copy_stream.go      |  3 +
 .../s3api_object_handlers_copy_stream_test.go | 73 +++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 weed/s3api/s3api_object_handlers_copy_stream_test.go

diff --git a/weed/s3api/s3api_object_handlers_copy_stream.go b/weed/s3api/s3api_object_handlers_copy_stream.go
index 910ec3aca5..32a8babf90 100644
--- a/weed/s3api/s3api_object_handlers_copy_stream.go
+++ b/weed/s3api/s3api_object_handlers_copy_stream.go
@@ -102,6 +102,9 @@ func (s3a *S3ApiServer) streamCopyChunkRange(
 	streamCtx, cancel := context.WithCancel(ctx)
 	defer cancel()
 	dstUrl := fmt.Sprintf("http://%s/%s", assignResult.Location.Url, assignResult.FileId)
+	if assignResult.Fsync {
+		dstUrl += "?fsync=true"
+	}
 	dstJwt := security.EncodedJwt(assignResult.Auth)
 	srcJwt := filer.JwtForVolumeServer(srcFileId)
 
diff --git a/weed/s3api/s3api_object_handlers_copy_stream_test.go b/weed/s3api/s3api_object_handlers_copy_stream_test.go
new file mode 100644
index 0000000000..9f0af11a40
--- /dev/null
+++ b/weed/s3api/s3api_object_handlers_copy_stream_test.go
@@ -0,0 +1,73 @@
+package s3api
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	util_http "github.com/seaweedfs/seaweedfs/weed/util/http"
+)
+
+func TestStreamCopyChunkRangeFsync(t *testing.T) {
+	util_http.InitGlobalHttpClient()
+	payload := bytes.Repeat([]byte("copy data"), 512)
+	source := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(payload)
+	}))
+	defer source.Close()
+
+	for _, tc := range []struct {
+		name      string
+		fsync     bool
+		wantQuery string
+		status    int
+		wantErr   bool
+	}{
+		{"without sync", false, "", http.StatusCreated, false},
+		{"durable copy", true, "true", http.StatusCreated, false},
+		{"durable write fails", true, "true", http.StatusInternalServerError, true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			destination := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if got := r.URL.Query().Get("fsync"); got != tc.wantQuery {
+					t.Errorf("upload fsync=%q, want %q", got, tc.wantQuery)
+				}
+				reader, err := r.MultipartReader()
+				if err != nil {
+					t.Error(err)
+					http.Error(w, "invalid upload", http.StatusBadRequest)
+					return
+				}
+				part, err := reader.NextPart()
+				if err != nil {
+					t.Error(err)
+					http.Error(w, "missing data", http.StatusBadRequest)
+					return
+				}
+				data, err := io.ReadAll(part)
+				if err != nil || !bytes.Equal(data, payload) {
+					t.Errorf("copied payload differs: %v", err)
+				}
+				w.WriteHeader(tc.status)
+				_, _ = fmt.Fprintf(w, `{"size":%d}`, len(payload))
+			}))
+			defer destination.Close()
+			assign := &filer_pb.AssignVolumeResponse{
+				FileId:   "1,test",
+				Location: &filer_pb.Location{Url: strings.TrimPrefix(destination.URL, "http://")},
+				Fsync:    tc.fsync,
+			}
+			err := (&S3ApiServer{}).streamCopyChunkRange(context.Background(), source.URL,
+				assign.FileId, 0, int64(len(payload)), true, assign, nil)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("stream copy error=%v, wantErr=%v", err, tc.wantErr)
+			}
+		})
+	}
+}