mount: test an append fsync after a peer's attribute-only change

A second mount's acknowledged chmod, chown, utimes or setxattr leaves
the content alone, so the writer's conditional content flush must still
publish its append and keep that change. On master the refused flush
surfaces as EIO from Fsync.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

weed/mount/content_flush_condition_test.go

@@ -53,6 +53,17 @@ func (s *contentFlushConditionFiler) CreateEntry(ctx context.Context, r *filer_p
 		},
 	}}, nil
 }
+func (s *contentFlushConditionFiler) UpdateEntry(ctx context.Context, r *filer_pb.UpdateEntryRequest) (*filer_pb.UpdateEntryResponse, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if clauses := r.GetCondition().GetClauses(); len(clauses) > 0 && !proto.Equal(clauses[0].GetExpectedEntry(), s.entry) {
+		return nil, status.Error(codes.FailedPrecondition, "entry changed")
+	}
+	s.calls++
+	s.entry = proto.Clone(r.Entry).(*filer_pb.Entry)
+	s.entry.CommitTsNs = 1000 + int64(s.calls)
+	return &filer_pb.UpdateEntryResponse{LogTsNs: 2000}, nil
+}
 func (s *contentFlushConditionFiler) LookupDirectoryEntry(ctx context.Context, r *filer_pb.LookupDirectoryEntryRequest) (*filer_pb.LookupDirectoryEntryResponse, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()

weed/mount/weedfs_attr_cas_test.go

@@ -138,6 +138,82 @@ func attributeAppendEntry(records int) *filer_pb.Entry {
 	return e
 }
 
+// A peer's acknowledged attribute change leaves the content alone, so our
+// append's conditional flush must still publish, keeping the peer's change.
+func TestAppendFlushAfterPeerAttributeChange(t *testing.T) {
+	for _, op := range []string{"none", "chmod", "chown", "utimes", "setxattr"} {
+		t.Run(op, func(t *testing.T) {
+			writer, peer := newInvalidateTestWFS(t), newInvalidateTestWFS(t)
+			peer.atimeMap = make(map[uint64]time.Time)
+			base := attributeAppendEntry(1)
+			base.CommitTsNs = 100
+			fake := &contentFlushConditionFiler{entry: proto.Clone(base).(*filer_pb.Entry)}
+			startFakeFiler(t, writer, fake)
+			startFakeFiler(t, peer, fake)
+			path := util.FullPath("/dir/file")
+			local := proto.Clone(base).(*filer_pb.Entry)
+			writer.mapPbIdFromFilerToLocal(local)
+			fh := newFileHandle(writer, 1, 42, local)
+			fh.RememberPath(path)
+			t.Cleanup(fh.dirtyPages.Destroy)
+			writer.fhMap.inode2fh[42], writer.fhMap.fh2inode[1] = fh, 42
+			appended := attributeAppendEntry(2).Chunks[1]
+			fh.UpdateEntry(func(e *filer_pb.Entry) {
+				e.Chunks = append(e.Chunks, appended)
+				e.Attributes.FileSize = 512
+			})
+			fh.dirtyMetadata = true
+
+			peer.inodeToPath.Lookup("/dir", 1, true, false, 0, false)
+			peer.inodeToPath.Lookup(path, 1, false, false, 42, true)
+			peer.inodeToPath.MarkChildrenCached("/dir")
+			if err := peer.metaCache.InsertEntry(context.Background(), filer.FromPbEntry("/dir", base), 1); err != nil {
+				t.Fatal(err)
+			}
+			code := fuse.OK
+			in := &fuse.SetAttrIn{}
+			in.NodeId = 42
+			switch op {
+			case "chmod":
+				in.Valid, in.Mode = fuse.FATTR_MODE, 0600
+			case "chown":
+				in.Valid, in.Owner.Uid, in.Owner.Gid = fuse.FATTR_UID|fuse.FATTR_GID, 1001, 21
+			case "utimes":
+				in.Valid, in.Mtime = fuse.FATTR_MTIME, 123
+			case "setxattr":
+				code = peer.SetXAttr(nil, &fuse.SetXAttrIn{InHeader: fuse.InHeader{NodeId: 42}}, "user.test", []byte("peer"))
+			}
+			if in.Valid != 0 {
+				code = peer.SetAttr(nil, in, &fuse.AttrOut{})
+			}
+			if code != fuse.OK {
+				t.Fatalf("peer %s: %v", op, code)
+			}
+
+			if code = writer.Fsync(nil, &fuse.FsyncIn{InHeader: fuse.InHeader{NodeId: 42}, Fh: 1}); code != fuse.OK {
+				t.Fatalf("append fsync after peer %s: %v", op, code)
+			}
+			fake.mu.Lock()
+			defer fake.mu.Unlock()
+			got := fake.entry
+			if len(got.Chunks) != 2 || got.Attributes.FileSize != 512 {
+				t.Fatalf("append not published after peer %s: %v", op, got)
+			}
+			a := got.Attributes
+			kept := map[string]bool{
+				"none":     true,
+				"chmod":    a.FileMode&0777 == 0600,
+				"chown":    a.Uid == 1001 && a.Gid == 21,
+				"utimes":   a.Mtime == 123,
+				"setxattr": string(got.Extended["xattr-user.test"]) == "peer",
+			}[op]
+			if !kept {
+				t.Fatalf("append flush dropped the peer's %s: %v", op, got)
+			}
+		})
+	}
+}
+
 func TestAttributeOnlyOpsPreserveAcknowledgedAppends(t *testing.T) {
 	for _, op := range []string{"chmod", "chown", "utimes", "setxattr", "removexattr"} {
 		for _, stale := range []bool{false, true} {