Fix overlay ctime stat cache

e2e_git_test.go

@@ -134,6 +134,36 @@ func TestE2EGitCleanState(t *testing.T) {
 	gitCmdQuiet(t, repo.mountPath, "diff", "--cached", "--quiet")
 }
 
+func TestE2EGitStatusDetectsSameSizeRewriteAfterMtimeRestore(t *testing.T) {
+	repo := newMountedE2ERepo(t)
+
+	readmePath := filepath.Join(repo.mountPath, "README.md")
+	assertGitStatus(t, repo.mountPath, map[string]string{})
+	st, err := os.Stat(readmePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	indexedMtime := st.ModTime()
+
+	updated := []byte(readFileEventually(t, readmePath))
+	if len(updated) == 0 {
+		t.Fatal("README.md is empty")
+	}
+	if updated[0] == 'x' {
+		updated[0] = 'y'
+	} else {
+		updated[0] = 'x'
+	}
+	if err := os.WriteFile(readmePath, updated, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Chtimes(readmePath, indexedMtime, indexedMtime); err != nil {
+		t.Fatal(err)
+	}
+
+	assertGitStatus(t, repo.mountPath, map[string]string{"README.md": " M"})
+}
+
 func TestE2EGitStatusPorcelain(t *testing.T) {
 	repo := newMountedE2ERepo(t)
 

internal/fusefs/fuse_unix.go

@@ -182,7 +182,7 @@ func (fs *ArtifactFuse) LookUpInode(_ context.Context, op *fuseops.LookUpInodeOp
 		return nil
 	}
 
-	mode, size, typ, mtime, err := fs.resolver.Getattr(childPath)
+	mode, size, typ, mtime, ctime, err := fs.resolver.Getattr(childPath)
 	if err != nil {
 		if errors.Is(err, iofs.ErrNotExist) {
 			return syscall.ENOENT
@@ -195,7 +195,7 @@ func (fs *ArtifactFuse) LookUpInode(_ context.Context, op *fuseops.LookUpInodeOp
 	fs.mu.Unlock()
 
 	op.Entry.Child = ref.ID
-	op.Entry.Attributes = inodeAttrs(mode, uint64(size), typ, mtime)
+	op.Entry.Attributes = inodeAttrs(mode, uint64(size), typ, mtime, ctime)
 	setChildEntryExpiry(&op.Entry, time.Second)
 	return nil
 }
@@ -212,11 +212,11 @@ func (fs *ArtifactFuse) GetInodeAttributes(_ context.Context, op *fuseops.GetIno
 		return nil
 	}
 
-	mode, size, typ, mtime, err := fs.resolver.Getattr(ref.Path)
+	mode, size, typ, mtime, ctime, err := fs.resolver.Getattr(ref.Path)
 	if err != nil {
 		return syscall.ENOENT
 	}
-	op.Attributes = inodeAttrs(mode, uint64(size), typ, mtime)
+	op.Attributes = inodeAttrs(mode, uint64(size), typ, mtime, ctime)
 	op.AttributesExpiration = attrExpiry(time.Second)
 	return nil
 }
@@ -233,17 +233,18 @@ func (fs *ArtifactFuse) SetInodeAttributes(ctx context.Context, op *fuseops.SetI
 	}
 	// Handle mtime updates (e.g., from touch)
 	if op.Mtime != nil {
-		fs.engine.SetMtime(ctx, ref.Path, *op.Mtime)
+		if err := fs.engine.SetMtime(ctx, ref.Path, *op.Mtime); err != nil {
+			if errors.Is(err, iofs.ErrInvalid) {
+				return syscall.ENOTSUP
+			}
+			return syscall.EIO
+		}
 	}
-	mode, size, typ, mtime, err := fs.resolver.Getattr(ref.Path)
+	mode, size, typ, mtime, ctime, err := fs.resolver.Getattr(ref.Path)
 	if err != nil {
 		return syscall.EIO
 	}
-	// If caller set mtime, return that instead of the stored value
-	if op.Mtime != nil {
-		mtime = *op.Mtime
-	}
-	op.Attributes = inodeAttrs(mode, uint64(size), typ, mtime)
+	op.Attributes = inodeAttrs(mode, uint64(size), typ, mtime, ctime)
 	op.AttributesExpiration = attrExpiry(time.Second)
 	return nil
 }
@@ -403,7 +404,8 @@ func (fs *ArtifactFuse) CreateFile(ctx context.Context, op *fuseops.CreateFileOp
 	fs.mu.Unlock()
 
 	op.Entry.Child = ref.ID
-	op.Entry.Attributes = inodeAttrs(uint32(op.Mode), 0, "file", time.Now())
+	now := time.Now()
+	op.Entry.Attributes = inodeAttrs(uint32(op.Mode), 0, "file", now, now)
 	setChildEntryExpiry(&op.Entry, time.Second)
 	op.Handle = handle
 	return nil
@@ -422,7 +424,8 @@ func (fs *ArtifactFuse) MkDir(ctx context.Context, op *fuseops.MkDirOp) error {
 	fs.mu.Unlock()
 
 	op.Entry.Child = ref.ID
-	op.Entry.Attributes = inodeAttrs(uint32(op.Mode)|uint32(os.ModeDir), 4096, "dir", time.Now())
+	now := time.Now()
+	op.Entry.Attributes = inodeAttrs(uint32(op.Mode)|uint32(os.ModeDir), 4096, "dir", now, now)
 	setChildEntryExpiry(&op.Entry, time.Second)
 	return nil
 }
@@ -464,6 +467,9 @@ func (fs *ArtifactFuse) Rename(ctx context.Context, op *fuseops.RenameOp) error
 	oldPath := cleanChildPath(oldParent.Path, op.OldName)
 	newPath := cleanChildPath(newParent.Path, op.NewName)
 	if err := fs.engine.Rename(ctx, oldPath, newPath); err != nil {
+		if errors.Is(err, iofs.ErrInvalid) {
+			return syscall.ENOTSUP
+		}
 		return syscall.EIO
 	}
 	return nil
@@ -587,15 +593,8 @@ func TryUnmount(mountPoint string) error {
 	return err
 }
 
-func inodeAttrs(mode uint32, size uint64, typ string, mtime time.Time) fuseops.InodeAttributes {
+func inodeAttrs(mode uint32, size uint64, typ string, mtime time.Time, ctime time.Time) fuseops.InodeAttributes {
 	m := os.FileMode(mode & 0o777)
-	if m == 0 {
-		if typ == "dir" {
-			m = 0o755
-		} else {
-			m = 0o644
-		}
-	}
 	switch typ {
 	case "dir":
 		m |= os.ModeDir
@@ -611,7 +610,9 @@ func inodeAttrs(mode uint32, size uint64, typ string, mtime time.Time) fuseops.I
 		Mode:  m,
 		Uid:   uint32(os.Getuid()),
 		Gid:   uint32(os.Getgid()),
+		Atime: mtime,
 		Mtime: mtime,
+		Ctime: ctime,
 	}
 }
 
@@ -630,12 +631,15 @@ func setChildEntryExpiry(entry *fuseops.ChildInodeEntry, ttl time.Duration) {
 }
 
 func (fs *ArtifactFuse) gitFileAttrs() fuseops.InodeAttributes {
+	now := time.Now()
 	return fuseops.InodeAttributes{
 		Size:  uint64(len(fs.gitfileContent)),
 		Mode:  0o644,
 		Nlink: 1,
 		Uid:   uint32(os.Getuid()),
 		Gid:   uint32(os.Getgid()),
-		Mtime: time.Now(),
+		Atime: now,
+		Mtime: now,
+		Ctime: now,
 	}
 }

internal/fusefs/fuse_unix_test.go

@@ -0,0 +1,48 @@
+//go:build !windows
+
+package fusefs
+
+import (
+	"testing"
+	"time"
+)
+
+func TestInodeAttrsPreservesSeparateTimes(t *testing.T) {
+	mtime := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
+	ctime := time.Date(2025, 1, 2, 0, 0, 0, 0, time.UTC)
+
+	attr := inodeAttrs(0o644, 12, "file", mtime, ctime)
+	if !attr.Atime.Equal(mtime) {
+		t.Fatalf("atime = %v, want %v", attr.Atime, mtime)
+	}
+	if !attr.Mtime.Equal(mtime) {
+		t.Fatalf("mtime = %v, want %v", attr.Mtime, mtime)
+	}
+	if !attr.Ctime.Equal(ctime) {
+		t.Fatalf("ctime = %v, want %v", attr.Ctime, ctime)
+	}
+}
+
+func TestInodeAttrsPreservesExplicitZeroDirMode(t *testing.T) {
+	now := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
+
+	attr := inodeAttrs(0, 4096, "dir", now, now)
+	if attr.Mode.Perm() != 0 {
+		t.Fatalf("mode perms = %#o, want 0", attr.Mode.Perm())
+	}
+	if !attr.Mode.IsDir() {
+		t.Fatalf("expected directory mode, got %#o", attr.Mode)
+	}
+}
+
+func TestGitFileAttrsUsesOneTimestamp(t *testing.T) {
+	fs := &ArtifactFuse{gitfileContent: []byte("gitdir: /tmp/repo/.git\n")}
+
+	attr := fs.gitFileAttrs()
+	if attr.Mtime.IsZero() || attr.Atime.IsZero() || attr.Ctime.IsZero() {
+		t.Fatalf("expected non-zero times: atime=%v mtime=%v ctime=%v", attr.Atime, attr.Mtime, attr.Ctime)
+	}
+	if !attr.Atime.Equal(attr.Mtime) || !attr.Ctime.Equal(attr.Mtime) {
+		t.Fatalf("expected .git attrs to use one timestamp: atime=%v mtime=%v ctime=%v", attr.Atime, attr.Mtime, attr.Ctime)
+	}
+}

internal/fusefs/merged.go

@@ -73,15 +73,16 @@ func (r *Resolver) Lookup(parent, name string) (ResolvedNode, error) {
 	return r.ResolvePath(p)
 }
 
-func (r *Resolver) Getattr(path string) (mode uint32, size int64, nodeType string, mtime time.Time, err error) {
+func (r *Resolver) Getattr(path string) (mode uint32, size int64, nodeType string, mtime time.Time, ctime time.Time, err error) {
 	n, err := r.ResolvePath(path)
 	if err != nil {
-		return 0, 0, "", time.Time{}, err
+		return 0, 0, "", time.Time{}, time.Time{}, err
 	}
 	if n.FromOverlay {
 		typ := n.Overlay.NodeType()
 		mt := time.Unix(0, n.Overlay.MtimeUnixNs)
-		return n.Overlay.Mode, n.Overlay.SizeBytes, typ, mt, nil
+		ct := time.Unix(0, n.Overlay.CtimeUnixNs)
+		return n.Overlay.Mode, n.Overlay.SizeBytes, typ, mt, ct, nil
 	}
 	mode = normalizeMode(n.Base.Mode, n.Base.Type)
 	// Base files use the HEAD commit timestamp for mtime so tools like
@@ -91,7 +92,7 @@ func (r *Resolver) Getattr(path string) (mode uint32, size int64, nodeType strin
 		ct = r.Generation() // fallback: commit time unavailable
 	}
 	mt := time.Unix(ct, 0)
-	return mode, n.Base.SizeBytes, n.Base.Type, mt, nil
+	return mode, n.Base.SizeBytes, n.Base.Type, mt, mt, nil
 }
 
 // normalizeMode ensures sane permission bits. Git tree entries have mode 040000
@@ -141,6 +142,9 @@ func (r *Resolver) ReaddirTyped(ctx context.Context, path string) ([]ReaddirEntr
 	ovEntries, err := r.Overlay.ListByPrefix(ctx, path)
 	if err == nil {
 		for _, e := range ovEntries {
+			if e.Path == path {
+				continue
+			}
 			name, ok := childName(path, e.Path)
 			if !ok {
 				continue