mount: bring a peer's metadata change into a dirty handle

A metadata-only event moved a dirty handle's base but left its live
entry, so the next flush read the peer's chmod as a local edit and
published the old mode back. Replay the handle's own changes onto the
peer's entry instead, as for a content change.

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

weed/mount/weedfs.go

@@ -1044,30 +1044,25 @@ func (wfs *WFS) invalidateOpenFileHandle(invalidation meta_cache.EntryInvalidati
 		fh.advanceEntryVersion(candidateTsNs, 0)
 		return
 	}
-	// Dirty pages overlay content, so only a content change invalidates them:
-	// a metadata-only event (chmod, touch, or a committed copy's own event
-	// against an approximate base) leaves them valid. A dirty handle likewise
-	// keeps its diverged entry unless foreign content supersedes it.
-	contentChanged := base == nil || !sameEntryContent(candidate, base)
-	if fh.dirtyMetadata && base != nil && (contentChanged || !sameContentFile(candidate, base)) {
-		// An unmergeable change or a replaced file keeps the writes; the
-		// flush reports the conflict.
-		if contentChanged && sameContentFile(candidate, base) && fh.mergePeerContent(candidate, base) {
+	// A dirty handle replays its own changes onto the peer's entry, keeping
+	// its pages. An unmergeable change or a replaced file keeps the writes;
+	// the flush reports the conflict.
+	if fh.dirtyMetadata && base != nil {
+		if sameContentFile(candidate, base) && fh.mergePeerContent(candidate, base) {
 			fh.adoptPeerBase(proto.Clone(candidate).(*filer_pb.Entry))
 			fh.advanceEntryVersion(candidateTsNs, 0)
 		}
 		return
 	}
-	if contentChanged {
+	// Dirty pages overlay content, so only a content change invalidates them:
+	// a metadata-only event (chmod, touch, or a committed copy's own event
+	// against an approximate base) leaves them valid.
+	if base == nil || !sameEntryContent(candidate, base) {
 		fh.dirtyPages.Destroy()
 		fh.dirtyPages = newPageWriter(fh, wfs.option.ChunkSizeLimit)
 	}
-	if contentChanged || !fh.dirtyMetadata {
-		fh.SetEntry(candidate)
-		fh.baseEntry.Store(proto.Clone(candidate).(*filer_pb.Entry))
-	} else {
-		fh.adoptPeerBase(proto.Clone(candidate).(*filer_pb.Entry))
-	}
+	fh.SetEntry(candidate)
+	fh.baseEntry.Store(proto.Clone(candidate).(*filer_pb.Entry))
 	fh.advanceEntryVersion(candidateTsNs, 0)
 	return
 }

weed/mount/weedfs_invalidate_open_handle_test.go

@@ -2276,3 +2276,52 @@ func TestPeerReplacementKeepsDirtyHandle(t *testing.T) {
 		})
 	}
 }
+
+// A peer's metadata-only change reaches a dirty handle's live entry, so its
+// next flush does not publish the stale value back; the handle's own edits
+// stay on top.
+func TestPeerChmodReachesDirtyHandle(t *testing.T) {
+	for _, name := range []string{"peer-only", "both-changed"} {
+		t.Run(name, func(t *testing.T) {
+			wfs := newInvalidateTestWFS(t)
+
+			inode := wfs.inodeToPath.Lookup(util.FullPath("/dir/file"), time.Now().Unix(), false, false, 0, false)
+			fh, _, _, _ := wfs.fhMap.AcquireFileHandle(wfs, inode, flushConditionEntry(1), 0, 0)
+			fh.AddChunks([]*filer_pb.FileChunk{{FileId: "1,0300000001", Offset: 2, Size: 1, ModifiedTsNs: 3}})
+			want := uint32(0600)
+			if name == "both-changed" {
+				fh.UpdateEntry(func(e *filer_pb.Entry) { e.Attributes.FileMode = 0640 })
+				want = 0640
+			}
+			fh.dirtyMetadata = true
+			pagesBefore := fh.dirtyPages
+
+			peer := flushConditionEntry(1)
+			peer.Attributes.FileMode = 0600
+			resp := &filer_pb.SubscribeMetadataResponse{
+				Directory: "/dir",
+				TsNs:      1500,
+				EventNotification: &filer_pb.EventNotification{
+					OldEntry:      flushConditionEntry(1),
+					NewEntry:      peer,
+					NewParentPath: "/dir",
+				},
+			}
+			if err := wfs.metaCache.ApplyMetadataResponse(context.Background(), resp, meta_cache.SubscriberMetadataResponseApplyOptions); err != nil {
+				t.Fatalf("apply: %v", err)
+			}
+			wfs.metaCache.WaitForEntryInvalidations()
+
+			if fh.dirtyPages != pagesBefore {
+				t.Fatal("dirty pages destroyed by a peer chmod")
+			}
+			entry := fh.GetEntry().GetEntry()
+			if got := entry.Attributes.FileMode; got != want || len(entry.Chunks) != 2 {
+				t.Fatalf("handle mode %o with %d chunks, want %o with its own chunk", got, len(entry.Chunks), want)
+			}
+			if base := fh.baseEntry.Load(); base.GetAttributes().GetFileMode() != 0600 {
+				t.Fatalf("base %v, want the peer's entry", base)
+			}
+		})
+	}
+}