diff --git a/microdroid/payload/README.md b/microdroid/payload/README.md
index b76eead..35502c1 100644
--- a/microdroid/payload/README.md
+++ b/microdroid/payload/README.md
@@ -7,7 +7,7 @@
 
 Payload disk has 1 + N(number of APEX/APK payloads) partitions.
 
-The first partition is a "metadata" partition which describes other partitions.
+The first partition is a "payload-metadata" partition which describes other partitions.
 And APEXes and an APK are following as separate partitions.
 
 For now, the order of partitions are important.
diff --git a/microdroid/payload/metadata/Android.bp b/microdroid/payload/metadata/Android.bp
index d3ec625..e4c7692 100644
--- a/microdroid/payload/metadata/Android.bp
+++ b/microdroid/payload/metadata/Android.bp
@@ -10,6 +10,7 @@
     prefer_rlib: true,
     edition: "2018",
     rustlibs: [
+        "libanyhow",
         "libmicrodroid_metadata_proto_rust",
         "libprotobuf",
     ],
diff --git a/microdroid/payload/metadata/src/lib.rs b/microdroid/payload/metadata/src/lib.rs
index 9c97411..eb9d90d 100644
--- a/microdroid/payload/metadata/src/lib.rs
+++ b/microdroid/payload/metadata/src/lib.rs
@@ -18,15 +18,15 @@
 //!   4 bytes : size(N) in big endian
 //!   N bytes : protobuf message for Metadata
 
+use anyhow::Result;
 use protobuf::Message;
-use std::io;
 use std::io::Read;
 use std::io::Write;
 
 pub use microdroid_metadata::metadata::{ApexPayload, ApkPayload, Metadata};
 
 /// Reads a metadata from a reader
-pub fn read_metadata<T: Read>(mut r: T) -> io::Result<Metadata> {
+pub fn read_metadata<T: Read>(mut r: T) -> Result<Metadata> {
     let mut buf = [0u8; 4];
     r.read_exact(&mut buf)?;
     let size = i32::from_be_bytes(buf);
@@ -34,9 +34,10 @@
 }
 
 /// Writes a metadata to a writer
-pub fn write_metadata<T: Write>(metadata: &Metadata, mut w: T) -> io::Result<()> {
+pub fn write_metadata<T: Write>(metadata: &Metadata, mut w: T) -> Result<()> {
     let mut buf = Vec::new();
     metadata.write_to_writer(&mut buf)?;
     w.write_all(&(buf.len() as i32).to_be_bytes())?;
-    w.write_all(&buf)
+    w.write_all(&buf)?;
+    Ok(())
 }
diff --git a/microdroid/payload/mk_payload.cc b/microdroid/payload/mk_payload.cc
index c31dcff..b27683c 100644
--- a/microdroid/payload/mk_payload.cc
+++ b/microdroid/payload/mk_payload.cc
@@ -302,7 +302,7 @@
 
     // put metadata at the first partition
     partitions.push_back(MultipleImagePartition{
-            .label = "metadata",
+            .label = "payload-metadata",
             .image_file_paths = {metadata_file},
             .type = kLinuxFilesystem,
             .read_only = true,
diff --git a/microdroid/sepolicy/system/private/apkdmverity.te b/microdroid/sepolicy/system/private/apkdmverity.te
index c6160be..8974a1d 100644
--- a/microdroid/sepolicy/system/private/apkdmverity.te
+++ b/microdroid/sepolicy/system/private/apkdmverity.te
@@ -6,7 +6,7 @@
 # allow domain transition from init
 init_daemon_domain(apkdmverity)
 
-# apkdmverity accesses /dev/block/by-name/metadata which points to
+# apkdmverity accesses "payload metadata disk" which points to
 # a /dev/vd* block device file.
 allow apkdmverity block_device:dir r_dir_perms;
 allow apkdmverity block_device:lnk_file r_file_perms;
diff --git a/microdroid/sepolicy/system/private/microdroid_manager.te b/microdroid/sepolicy/system/private/microdroid_manager.te
index 81a6839..53c63ae 100644
--- a/microdroid/sepolicy/system/private/microdroid_manager.te
+++ b/microdroid/sepolicy/system/private/microdroid_manager.te
@@ -6,8 +6,7 @@
 # allow domain transition from init
 init_daemon_domain(microdroid_manager)
 
-# microdroid_manager accesses /dev/block/by-name/metadata which points to
-# a /dev/vd* block device file.
+# microdroid_manager accesses a virtual disk block device to read VM payload
 allow microdroid_manager block_device:dir r_dir_perms;
 allow microdroid_manager block_device:lnk_file r_file_perms;
 allow microdroid_manager vd_device:blk_file r_file_perms;