3 files changed, 49 insertions, 41 deletions
diff --git a/pkg/sentry/fsimpl/overlay/BUILD b/pkg/sentry/fsimpl/overlay/BUILD
deleted file mode 100644
index 8cf5b35d3..000000000
--- a/pkg/sentry/fsimpl/overlay/BUILD
+++ /dev/null
@@ -1,41 +0,0 @@
-load("//tools:defs.bzl", "go_library")
-load("//tools/go_generics:defs.bzl", "go_template_instance")
-
-licenses(["notice"])
-
-go_template_instance(
-    name = "fstree",
-    out = "fstree.go",
-    package = "overlay",
-    prefix = "generic",
-    template = "//pkg/sentry/vfs/genericfstree:generic_fstree",
-    types = {
-        "Dentry": "dentry",
-    },
-)
-
-go_library(
-    name = "overlay",
-    srcs = [
-        "copy_up.go",
-        "directory.go",
-        "filesystem.go",
-        "fstree.go",
-        "non_directory.go",
-        "overlay.go",
-    ],
-    visibility = ["//pkg/sentry:internal"],
-    deps = [
-        "//pkg/abi/linux",
-        "//pkg/context",
-        "//pkg/fspath",
-        "//pkg/sentry/fs/lock",
-        "//pkg/sentry/kernel/auth",
-        "//pkg/sentry/memmap",
-        "//pkg/sentry/socket/unix/transport",
-        "//pkg/sentry/vfs",
-        "//pkg/sync",
-        "//pkg/syserror",
-        "//pkg/usermem",
-    ],
-)
diff --git a/pkg/sentry/fsimpl/overlay/fstree.go b/pkg/sentry/fsimpl/overlay/fstree.go
new file mode 100644
index 000000000..1fa1b4ad3
--- /dev/null
+++ b/pkg/sentry/fsimpl/overlay/fstree.go
@@ -0,0 +1,46 @@
+package overlay
+
+import (
+	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
+// either d2's parent or an ancestor of d2's parent.
+func genericIsAncestorDentry(d, d2 *dentry) bool {
+	for d2 != nil {
+		if d2.parent == d {
+			return true
+		}
+		if d2.parent == d2 {
+			return false
+		}
+		d2 = d2.parent
+	}
+	return false
+}
+
+// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
+func genericParentOrSelf(d *dentry) *dentry {
+	if d.parent != nil {
+		return d.parent
+	}
+	return d
+}
+
+// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
+func genericPrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *dentry, b *fspath.Builder) error {
+	for {
+		if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
+			return vfs.PrependPathAtVFSRootError{}
+		}
+		if &d.vfsd == mnt.Root() {
+			return nil
+		}
+		if d.parent == nil {
+			return vfs.PrependPathAtNonMountRootError{}
+		}
+		b.PrependComponent(d.name)
+		d = d.parent
+	}
+}
diff --git a/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go b/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go
new file mode 100644
index 000000000..0c184964f
--- /dev/null
+++ b/pkg/sentry/fsimpl/overlay/overlay_state_autogen.go
@@ -0,0 +1,3 @@
+// automatically generated by stateify.
+
+package overlay