diff --git a/Cargo.lock b/Cargo.lock
index b0f2f6348..a544e9eff 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -162,6 +162,7 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
+ "thiserror",
  "virtio-bindings",
  "vm-memory",
  "vm-virtio",
diff --git a/block_util/Cargo.toml b/block_util/Cargo.toml
index 4e137a970..232113545 100644
--- a/block_util/Cargo.toml
+++ b/block_util/Cargo.toml
@@ -15,6 +15,7 @@ log = "0.4.13"
 serde = ">=1.0.27"
 serde_derive = ">=1.0.27"
 serde_json = ">=1.0.9"
+thiserror = "1.0"
 virtio-bindings = { version = "0.1", features = ["virtio-v5_0_0"]}
 vm-memory = { version = "0.4.0", features = ["backend-mmap", "backend-atomic"] }
 vm-virtio = { path = "../vm-virtio" }
diff --git a/block_util/src/async_io.rs b/block_util/src/async_io.rs
new file mode 100644
index 000000000..25e1880dc
--- /dev/null
+++ b/block_util/src/async_io.rs
@@ -0,0 +1,56 @@
+// Copyright © 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
+
+use thiserror::Error;
+use vmm_sys_util::eventfd::EventFd;
+
+#[derive(Error, Debug)]
+pub enum DiskFileError {
+    /// Failed getting disk file size.
+    #[error("Failed getting disk file size: {0}")]
+    Size(#[source] std::io::Error),
+    /// Failed creating a new AsyncIo.
+    #[error("Failed creating a new AsyncIo: {0}")]
+    NewAsyncIo(#[source] std::io::Error),
+}
+
+pub type DiskFileResult<T> = std::result::Result<T, DiskFileError>;
+
+pub trait DiskFile: Send + Sync {
+    fn size(&mut self) -> DiskFileResult<u64>;
+    fn new_async_io(&self, ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>>;
+}
+
+#[derive(Error, Debug)]
+pub enum AsyncIoError {
+    /// Failed vectored reading from file.
+    #[error("Failed vectored reading from file: {0}")]
+    ReadVectored(#[source] std::io::Error),
+    /// Failed vectored writing to file.
+    #[error("Failed vectored writing to file: {0}")]
+    WriteVectored(#[source] std::io::Error),
+    /// Failed synchronizing file.
+    #[error("Failed synchronizing file: {0}")]
+    Fsync(#[source] std::io::Error),
+}
+
+pub type AsyncIoResult<T> = std::result::Result<T, AsyncIoError>;
+
+pub trait AsyncIo: Send + Sync {
+    fn notifier(&self) -> &EventFd;
+    fn read_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()>;
+    fn write_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()>;
+    fn fsync(&mut self, user_data: Option<u64>) -> AsyncIoResult<()>;
+    fn complete(&mut self) -> Vec<(u64, i32)>;
+}
diff --git a/block_util/src/lib.rs b/block_util/src/lib.rs
index 5514e1a72..71b89a994 100644
--- a/block_util/src/lib.rs
+++ b/block_util/src/lib.rs
@@ -13,6 +13,8 @@ extern crate log;
 #[macro_use]
 extern crate serde_derive;
 
+pub mod async_io;
+
 #[cfg(feature = "io_uring")]
 use io_uring::Probe;
 use io_uring::{opcode, squeue, IoUring};