diff --git a/Cargo.lock b/Cargo.lock
index 22850cbe0..29872a66d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1017,6 +1017,7 @@ dependencies = [
  "libc 0.2.65 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "vm-memory 0.1.0 (git+https://github.com/rust-vmm/vm-memory)",
+ "vm-virtio 0.1.0",
 ]
 
 [[package]]
diff --git a/vhost_user_fs/Cargo.toml b/vhost_user_fs/Cargo.toml
index 826b26d74..8ffc1922a 100644
--- a/vhost_user_fs/Cargo.toml
+++ b/vhost_user_fs/Cargo.toml
@@ -9,3 +9,4 @@ bitflags = "1.1.0"
 libc = "0.2.65"
 log = "0.4.8"
 vm-memory = { git = "https://github.com/rust-vmm/vm-memory" }
+vm-virtio = { path = "../vm-virtio" }
diff --git a/vhost_user_fs/src/descriptor_utils.rs b/vhost_user_fs/src/descriptor_utils.rs
new file mode 100644
index 000000000..4db6a5ae1
--- /dev/null
+++ b/vhost_user_fs/src/descriptor_utils.rs
@@ -0,0 +1,985 @@
+// Copyright 2019 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+use std::cmp;
+use std::collections::VecDeque;
+use std::fmt::{self, Display};
+use std::io::{self, Read, Write};
+use std::mem::{size_of, MaybeUninit};
+use std::ops::Deref;
+use std::ptr::copy_nonoverlapping;
+use std::result;
+
+use vm_memory::{
+    Address, ByteValued, Bytes, GuestAddress, GuestMemory, GuestMemoryError, GuestMemoryMmap,
+    GuestMemoryRegion, Le16, Le32, Le64, VolatileMemory, VolatileMemoryError, VolatileSlice,
+};
+use vm_virtio::DescriptorChain;
+
+use crate::file_traits::{FileReadWriteAtVolatile, FileReadWriteVolatile};
+
+#[derive(Debug)]
+pub enum Error {
+    DescriptorChainOverflow,
+    FindMemoryRegion,
+    GuestMemoryError(GuestMemoryError),
+    InvalidChain,
+    IoError(io::Error),
+    SplitOutOfBounds(usize),
+    VolatileMemoryError(VolatileMemoryError),
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::Error::*;
+
+        match self {
+            DescriptorChainOverflow => write!(
+                f,
+                "the combined length of all the buffers in a `DescriptorChain` would overflow"
+            ),
+            FindMemoryRegion => write!(f, "no memory region for this address range"),
+            GuestMemoryError(e) => write!(f, "descriptor guest memory error: {}", e),
+            InvalidChain => write!(f, "invalid descriptor chain"),
+            IoError(e) => write!(f, "descriptor I/O error: {}", e),
+            SplitOutOfBounds(off) => write!(f, "`DescriptorChain` split is out of bounds: {}", off),
+            VolatileMemoryError(e) => write!(f, "volatile memory error: {}", e),
+        }
+    }
+}
+
+pub type Result<T> = result::Result<T, Error>;
+
+impl std::error::Error for Error {}
+
+#[derive(Clone)]
+struct DescriptorChainConsumer<'a> {
+    buffers: VecDeque<VolatileSlice<'a>>,
+    bytes_consumed: usize,
+}
+
+impl<'a> DescriptorChainConsumer<'a> {
+    fn available_bytes(&self) -> usize {
+        // This is guaranteed not to overflow because the total length of the chain
+        // is checked during all creations of `DescriptorChainConsumer` (see
+        // `Reader::new()` and `Writer::new()`).
+        self.buffers
+            .iter()
+            .fold(0usize, |count, vs| count + vs.len() as usize)
+    }
+
+    fn bytes_consumed(&self) -> usize {
+        self.bytes_consumed
+    }
+
+    /// Consumes at most `count` bytes from the `DescriptorChain`. Callers must provide a function
+    /// that takes a `&[VolatileSlice]` and returns the total number of bytes consumed. This
+    /// function guarantees that the combined length of all the slices in the `&[VolatileSlice]` is
+    /// less than or equal to `count`.
+    ///
+    /// # Errors
+    ///
+    /// If the provided function returns any error then no bytes are consumed from the buffer and
+    /// the error is returned to the caller.
+    fn consume<F>(&mut self, count: usize, f: F) -> io::Result<usize>
+    where
+        F: FnOnce(&[VolatileSlice]) -> io::Result<usize>,
+    {
+        let mut buflen = 0;
+        let mut bufs = Vec::with_capacity(self.buffers.len());
+        for &vs in &self.buffers {
+            if buflen >= count {
+                break;
+            }
+
+            bufs.push(vs);
+
+            let rem = count - buflen;
+            if rem < vs.len() {
+                buflen += rem;
+            } else {
+                buflen += vs.len() as usize;
+            }
+        }
+
+        if bufs.is_empty() {
+            return Ok(0);
+        }
+
+        let bytes_consumed = f(&*bufs)?;
+
+        // This can happen if a driver tricks a device into reading/writing more data than
+        // fits in a `usize`.
+        let total_bytes_consumed =
+            self.bytes_consumed
+                .checked_add(bytes_consumed)
+                .ok_or_else(|| {
+                    io::Error::new(io::ErrorKind::InvalidData, Error::DescriptorChainOverflow)
+                })?;
+
+        let mut rem = bytes_consumed;
+        while let Some(vs) = self.buffers.pop_front() {
+            if rem < vs.len() {
+                // Split the slice and push the remainder back into the buffer list. Safe because we
+                // know that `rem` is not out of bounds due to the check and we checked the bounds
+                // on `vs` when we added it to the buffer list.
+                self.buffers.push_front(vs.offset(rem).unwrap());
+                break;
+            }
+
+            // No need for checked math because we know that `vs.size() <= rem`.
+            rem -= vs.len();
+        }
+
+        self.bytes_consumed = total_bytes_consumed;
+
+        Ok(bytes_consumed)
+    }
+
+    fn split_at(&mut self, offset: usize) -> Result<DescriptorChainConsumer<'a>> {
+        let mut rem = offset;
+        let pos = self.buffers.iter().position(|vs| {
+            if rem < vs.len() {
+                true
+            } else {
+                rem -= vs.len();
+                false
+            }
+        });
+
+        if let Some(at) = pos {
+            let mut other = self.buffers.split_off(at);
+
+            if rem > 0 {
+                // There must be at least one element in `other` because we checked
+                // its `size` value in the call to `position` above.
+                let front = other.pop_front().expect("empty VecDeque after split");
+                self.buffers
+                    .push_back(front.offset(rem).map_err(Error::VolatileMemoryError)?);
+                other.push_front(front.offset(rem).map_err(Error::VolatileMemoryError)?);
+            }
+
+            Ok(DescriptorChainConsumer {
+                buffers: other,
+                bytes_consumed: 0,
+            })
+        } else if rem == 0 {
+            Ok(DescriptorChainConsumer {
+                buffers: VecDeque::new(),
+                bytes_consumed: 0,
+            })
+        } else {
+            Err(Error::SplitOutOfBounds(offset))
+        }
+    }
+}
+
+/// Provides high-level interface over the sequence of memory regions
+/// defined by readable descriptors in the descriptor chain.
+///
+/// Note that virtio spec requires driver to place any device-writable
+/// descriptors after any device-readable descriptors (2.6.4.2 in Virtio Spec v1.1).
+/// Reader will skip iterating over descriptor chain when first writable
+/// descriptor is encountered.
+#[derive(Clone)]
+pub struct Reader<'a> {
+    buffer: DescriptorChainConsumer<'a>,
+}
+
+impl<'a> Reader<'a> {
+    /// Construct a new Reader wrapper over `desc_chain`.
+    pub fn new(mem: &'a GuestMemoryMmap, desc_chain: DescriptorChain<'a>) -> Result<Reader<'a>> {
+        let mut total_len: usize = 0;
+        let buffers = desc_chain
+            .into_iter()
+            .readable()
+            .map(|desc| {
+                // Verify that summing the descriptor sizes does not overflow.
+                // This can happen if a driver tricks a device into reading more data than
+                // fits in a `usize`.
+                total_len = total_len
+                    .checked_add(desc.len as usize)
+                    .ok_or(Error::DescriptorChainOverflow)?;
+
+                let region = mem.find_region(desc.addr).ok_or(Error::FindMemoryRegion)?;
+                let offset = desc
+                    .addr
+                    .checked_sub(region.start_addr().raw_value())
+                    .unwrap();
+                region
+                    .deref()
+                    .get_slice(offset.raw_value() as usize, desc.len as usize)
+                    .map_err(Error::VolatileMemoryError)
+            })
+            .collect::<Result<VecDeque<VolatileSlice<'a>>>>()?;
+        Ok(Reader {
+            buffer: DescriptorChainConsumer {
+                buffers,
+                bytes_consumed: 0,
+            },
+        })
+    }
+
+    /// Reads an object from the descriptor chain buffer.
+    pub fn read_obj<T: ByteValued>(&mut self) -> io::Result<T> {
+        let mut obj = MaybeUninit::<T>::uninit();
+
+        // Safe because `MaybeUninit` guarantees that the pointer is valid for
+        // `size_of::<T>()` bytes.
+        let buf = unsafe {
+            ::std::slice::from_raw_parts_mut(obj.as_mut_ptr() as *mut u8, size_of::<T>())
+        };
+
+        self.read_exact(buf)?;
+
+        // Safe because any type that implements `ByteValued` can be considered initialized
+        // even if it is filled with random data.
+        Ok(unsafe { obj.assume_init() })
+    }
+
+    /// Reads data from the descriptor chain buffer into a file descriptor.
+    /// Returns the number of bytes read from the descriptor chain buffer.
+    /// The number of bytes read can be less than `count` if there isn't
+    /// enough data in the descriptor chain buffer.
+    pub fn read_to<F: FileReadWriteVolatile>(
+        &mut self,
+        mut dst: F,
+        count: usize,
+    ) -> io::Result<usize> {
+        self.buffer
+            .consume(count, |bufs| dst.write_vectored_volatile(bufs))
+    }
+
+    /// Reads data from the descriptor chain buffer into a File at offset `off`.
+    /// Returns the number of bytes read from the descriptor chain buffer.
+    /// The number of bytes read can be less than `count` if there isn't
+    /// enough data in the descriptor chain buffer.
+    pub fn read_to_at<F: FileReadWriteAtVolatile>(
+        &mut self,
+        mut dst: F,
+        count: usize,
+        off: u64,
+    ) -> io::Result<usize> {
+        self.buffer
+            .consume(count, |bufs| dst.write_vectored_at_volatile(bufs, off))
+    }
+
+    pub fn read_exact_to<F: FileReadWriteVolatile>(
+        &mut self,
+        mut dst: F,
+        mut count: usize,
+    ) -> io::Result<()> {
+        while count > 0 {
+            match self.read_to(&mut dst, count) {
+                Ok(0) => {
+                    return Err(io::Error::new(
+                        io::ErrorKind::UnexpectedEof,
+                        "failed to fill whole buffer",
+                    ))
+                }
+                Ok(n) => count -= n,
+                Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+                Err(e) => return Err(e),
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Returns number of bytes available for reading.  May return an error if the combined
+    /// lengths of all the buffers in the DescriptorChain would cause an integer overflow.
+    pub fn available_bytes(&self) -> usize {
+        self.buffer.available_bytes()
+    }
+
+    /// Returns number of bytes already read from the descriptor chain buffer.
+    pub fn bytes_read(&self) -> usize {
+        self.buffer.bytes_consumed()
+    }
+
+    /// Splits this `Reader` into two at the given offset in the `DescriptorChain` buffer.
+    /// After the split, `self` will be able to read up to `offset` bytes while the returned
+    /// `Reader` can read up to `available_bytes() - offset` bytes.  Returns an error if
+    /// `offset > self.available_bytes()`.
+    pub fn split_at(&mut self, offset: usize) -> Result<Reader<'a>> {
+        self.buffer.split_at(offset).map(|buffer| Reader { buffer })
+    }
+}
+
+impl<'a> io::Read for Reader<'a> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.buffer.consume(buf.len(), |bufs| {
+            let mut rem = buf;
+            let mut total = 0;
+            for vs in bufs {
+                let copy_len = cmp::min(rem.len(), vs.len());
+
+                // Safe because we have already verified that `vs` points to valid memory.
+                unsafe {
+                    copy_nonoverlapping(vs.as_ptr() as *const u8, rem.as_mut_ptr(), copy_len);
+                }
+                rem = &mut rem[copy_len..];
+                total += copy_len;
+            }
+            Ok(total)
+        })
+    }
+}
+
+/// Provides high-level interface over the sequence of memory regions
+/// defined by writable descriptors in the descriptor chain.
+///
+/// Note that virtio spec requires driver to place any device-writable
+/// descriptors after any device-readable descriptors (2.6.4.2 in Virtio Spec v1.1).
+/// Writer will start iterating the descriptors from the first writable one and will
+/// assume that all following descriptors are writable.
+#[derive(Clone)]
+pub struct Writer<'a> {
+    buffer: DescriptorChainConsumer<'a>,
+}
+
+impl<'a> Writer<'a> {
+    /// Construct a new Writer wrapper over `desc_chain`.
+    pub fn new(mem: &'a GuestMemoryMmap, desc_chain: DescriptorChain<'a>) -> Result<Writer<'a>> {
+        let mut total_len: usize = 0;
+        let buffers = desc_chain
+            .into_iter()
+            .writable()
+            .map(|desc| {
+                // Verify that summing the descriptor sizes does not overflow.
+                // This can happen if a driver tricks a device into writing more data than
+                // fits in a `usize`.
+                total_len = total_len
+                    .checked_add(desc.len as usize)
+                    .ok_or(Error::DescriptorChainOverflow)?;
+
+                let region = mem.find_region(desc.addr).ok_or(Error::FindMemoryRegion)?;
+                let offset = desc
+                    .addr
+                    .checked_sub(region.start_addr().raw_value())
+                    .unwrap();
+                region
+                    .deref()
+                    .get_slice(offset.raw_value() as usize, desc.len as usize)
+                    .map_err(Error::VolatileMemoryError)
+            })
+            .collect::<Result<VecDeque<VolatileSlice<'a>>>>()?;
+
+        Ok(Writer {
+            buffer: DescriptorChainConsumer {
+                buffers,
+                bytes_consumed: 0,
+            },
+        })
+    }
+
+    /// Writes an object to the descriptor chain buffer.
+    pub fn write_obj<T: ByteValued>(&mut self, val: T) -> io::Result<()> {
+        self.write_all(val.as_slice())
+    }
+
+    /// Returns number of bytes available for writing.  May return an error if the combined
+    /// lengths of all the buffers in the DescriptorChain would cause an overflow.
+    pub fn available_bytes(&self) -> usize {
+        self.buffer.available_bytes()
+    }
+
+    /// Writes data to the descriptor chain buffer from a file descriptor.
+    /// Returns the number of bytes written to the descriptor chain buffer.
+    /// The number of bytes written can be less than `count` if
+    /// there isn't enough data in the descriptor chain buffer.
+    pub fn write_from<F: FileReadWriteVolatile>(
+        &mut self,
+        mut src: F,
+        count: usize,
+    ) -> io::Result<usize> {
+        self.buffer
+            .consume(count, |bufs| src.read_vectored_volatile(bufs))
+    }
+
+    /// Writes data to the descriptor chain buffer from a File at offset `off`.
+    /// Returns the number of bytes written to the descriptor chain buffer.
+    /// The number of bytes written can be less than `count` if
+    /// there isn't enough data in the descriptor chain buffer.
+    pub fn write_from_at<F: FileReadWriteAtVolatile>(
+        &mut self,
+        mut src: F,
+        count: usize,
+        off: u64,
+    ) -> io::Result<usize> {
+        self.buffer
+            .consume(count, |bufs| src.read_vectored_at_volatile(bufs, off))
+    }
+
+    pub fn write_all_from<F: FileReadWriteVolatile>(
+        &mut self,
+        mut src: F,
+        mut count: usize,
+    ) -> io::Result<()> {
+        while count > 0 {
+            match self.write_from(&mut src, count) {
+                Ok(0) => {
+                    return Err(io::Error::new(
+                        io::ErrorKind::WriteZero,
+                        "failed to write whole buffer",
+                    ))
+                }
+                Ok(n) => count -= n,
+                Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+                Err(e) => return Err(e),
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Returns number of bytes already written to the descriptor chain buffer.
+    pub fn bytes_written(&self) -> usize {
+        self.buffer.bytes_consumed()
+    }
+
+    /// Splits this `Writer` into two at the given offset in the `DescriptorChain` buffer.
+    /// After the split, `self` will be able to write up to `offset` bytes while the returned
+    /// `Writer` can write up to `available_bytes() - offset` bytes.  Returns an error if
+    /// `offset > self.available_bytes()`.
+    pub fn split_at(&mut self, offset: usize) -> Result<Writer<'a>> {
+        self.buffer.split_at(offset).map(|buffer| Writer { buffer })
+    }
+}
+
+impl<'a> io::Write for Writer<'a> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.buffer.consume(buf.len(), |bufs| {
+            let mut rem = buf;
+            let mut total = 0;
+            for vs in bufs {
+                let copy_len = cmp::min(rem.len(), vs.len());
+
+                // Safe because we have already verified that `vs` points to valid memory.
+                unsafe {
+                    copy_nonoverlapping(rem.as_ptr(), vs.as_ptr(), copy_len);
+                }
+                rem = &rem[copy_len..];
+                total += copy_len;
+            }
+            Ok(total)
+        })
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        // Nothing to flush since the writes go straight into the buffer.
+        Ok(())
+    }
+}
+
+const VIRTQ_DESC_F_NEXT: u16 = 0x1;
+const VIRTQ_DESC_F_WRITE: u16 = 0x2;
+
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub enum DescriptorType {
+    Readable,
+    Writable,
+}
+
+#[derive(Copy, Clone, Debug, Default)]
+#[repr(C)]
+struct virtq_desc {
+    addr: Le64,
+    len: Le32,
+    flags: Le16,
+    next: Le16,
+}
+
+// Safe because it only has data and has no implicit padding.
+unsafe impl ByteValued for virtq_desc {}
+
+/// Test utility function to create a descriptor chain in guest memory.
+pub fn create_descriptor_chain(
+    memory: &GuestMemoryMmap,
+    descriptor_array_addr: GuestAddress,
+    mut buffers_start_addr: GuestAddress,
+    descriptors: Vec<(DescriptorType, u32)>,
+    spaces_between_regions: u32,
+) -> Result<DescriptorChain> {
+    let descriptors_len = descriptors.len();
+    for (index, (type_, size)) in descriptors.into_iter().enumerate() {
+        let mut flags = 0;
+        if let DescriptorType::Writable = type_ {
+            flags |= VIRTQ_DESC_F_WRITE;
+        }
+        if index + 1 < descriptors_len {
+            flags |= VIRTQ_DESC_F_NEXT;
+        }
+
+        let index = index as u16;
+        let desc = virtq_desc {
+            addr: buffers_start_addr.raw_value().into(),
+            len: size.into(),
+            flags: flags.into(),
+            next: (index + 1).into(),
+        };
+
+        let offset = size + spaces_between_regions;
+        buffers_start_addr = buffers_start_addr
+            .checked_add(u64::from(offset))
+            .ok_or(Error::InvalidChain)?;
+
+        let _ = memory.write_obj(
+            desc,
+            descriptor_array_addr
+                .checked_add(u64::from(index) * std::mem::size_of::<virtq_desc>() as u64)
+                .ok_or(Error::InvalidChain)?,
+        );
+    }
+
+    DescriptorChain::checked_new(memory, descriptor_array_addr, 0x100, 0, None)
+        .ok_or(Error::InvalidChain)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn reader_test_simple_chain() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 8),
+                (Readable, 16),
+                (Readable, 18),
+                (Readable, 64),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+        assert_eq!(reader.available_bytes(), 106);
+        assert_eq!(reader.bytes_read(), 0);
+
+        let mut buffer = [0 as u8; 64];
+        if let Err(_) = reader.read_exact(&mut buffer) {
+            panic!("read_exact should not fail here");
+        }
+
+        assert_eq!(reader.available_bytes(), 42);
+        assert_eq!(reader.bytes_read(), 64);
+
+        match reader.read(&mut buffer) {
+            Err(_) => panic!("read should not fail here"),
+            Ok(length) => assert_eq!(length, 42),
+        }
+
+        assert_eq!(reader.available_bytes(), 0);
+        assert_eq!(reader.bytes_read(), 106);
+    }
+
+    #[test]
+    fn writer_test_simple_chain() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Writable, 8),
+                (Writable, 16),
+                (Writable, 18),
+                (Writable, 64),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut writer = Writer::new(&memory, chain).expect("failed to create Writer");
+        assert_eq!(writer.available_bytes(), 106);
+        assert_eq!(writer.bytes_written(), 0);
+
+        let mut buffer = [0 as u8; 64];
+        if let Err(_) = writer.write_all(&mut buffer) {
+            panic!("write_all should not fail here");
+        }
+
+        assert_eq!(writer.available_bytes(), 42);
+        assert_eq!(writer.bytes_written(), 64);
+
+        match writer.write(&mut buffer) {
+            Err(_) => panic!("write should not fail here"),
+            Ok(length) => assert_eq!(length, 42),
+        }
+
+        assert_eq!(writer.available_bytes(), 0);
+        assert_eq!(writer.bytes_written(), 106);
+    }
+
+    #[test]
+    fn reader_test_incompatible_chain() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Writable, 8)],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+        assert_eq!(reader.available_bytes(), 0);
+        assert_eq!(reader.bytes_read(), 0);
+
+        assert!(reader.read_obj::<u8>().is_err());
+
+        assert_eq!(reader.available_bytes(), 0);
+        assert_eq!(reader.bytes_read(), 0);
+    }
+
+    #[test]
+    fn writer_test_incompatible_chain() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Readable, 8)],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut writer = Writer::new(&memory, chain).expect("failed to create Writer");
+        assert_eq!(writer.available_bytes(), 0);
+        assert_eq!(writer.bytes_written(), 0);
+
+        assert!(writer.write_obj(0u8).is_err());
+
+        assert_eq!(writer.available_bytes(), 0);
+        assert_eq!(writer.bytes_written(), 0);
+    }
+
+    #[test]
+    fn reader_writer_shared_chain() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain.clone()).expect("failed to create Reader");
+        let mut writer = Writer::new(&memory, chain).expect("failed to create Writer");
+
+        assert_eq!(reader.bytes_read(), 0);
+        assert_eq!(writer.bytes_written(), 0);
+
+        let mut buffer = Vec::with_capacity(200);
+
+        assert_eq!(
+            reader
+                .read_to_end(&mut buffer)
+                .expect("read should not fail here"),
+            128
+        );
+
+        // The writable descriptors are only 68 bytes long.
+        writer
+            .write_all(&buffer[..68])
+            .expect("write should not fail here");
+
+        assert_eq!(reader.available_bytes(), 0);
+        assert_eq!(reader.bytes_read(), 128);
+        assert_eq!(writer.available_bytes(), 0);
+        assert_eq!(writer.bytes_written(), 68);
+    }
+
+    #[test]
+    fn reader_writer_shattered_object() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let secret: Le32 = 0x12345678.into();
+
+        // Create a descriptor chain with memory regions that are properly separated.
+        let chain_writer = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Writable, 1), (Writable, 1), (Writable, 1), (Writable, 1)],
+            123,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut writer = Writer::new(&memory, chain_writer).expect("failed to create Writer");
+        if let Err(_) = writer.write_obj(secret) {
+            panic!("write_obj should not fail here");
+        }
+
+        // Now create new descriptor chain pointing to the same memory and try to read it.
+        let chain_reader = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Readable, 1), (Readable, 1), (Readable, 1), (Readable, 1)],
+            123,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain_reader).expect("failed to create Reader");
+        match reader.read_obj::<Le32>() {
+            Err(_) => panic!("read_obj should not fail here"),
+            Ok(read_secret) => assert_eq!(read_secret, secret),
+        }
+    }
+
+    #[test]
+    fn reader_unexpected_eof() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Readable, 256), (Readable, 256)],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let mut buf = Vec::with_capacity(1024);
+        buf.resize(1024, 0);
+
+        assert_eq!(
+            reader
+                .read_exact(&mut buf[..])
+                .expect_err("read more bytes than available")
+                .kind(),
+            io::ErrorKind::UnexpectedEof
+        );
+    }
+
+    #[test]
+    fn split_border() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let other = reader.split_at(32).expect("failed to split Reader");
+        assert_eq!(reader.available_bytes(), 32);
+        assert_eq!(other.available_bytes(), 96);
+    }
+
+    #[test]
+    fn split_middle() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let other = reader.split_at(24).expect("failed to split Reader");
+        assert_eq!(reader.available_bytes(), 24);
+        assert_eq!(other.available_bytes(), 104);
+    }
+
+    #[test]
+    fn split_end() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let other = reader.split_at(128).expect("failed to split Reader");
+        assert_eq!(reader.available_bytes(), 128);
+        assert_eq!(other.available_bytes(), 0);
+    }
+
+    #[test]
+    fn split_beginning() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let other = reader.split_at(0).expect("failed to split Reader");
+        assert_eq!(reader.available_bytes(), 0);
+        assert_eq!(other.available_bytes(), 128);
+    }
+
+    #[test]
+    fn split_outofbounds() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![
+                (Readable, 16),
+                (Readable, 16),
+                (Readable, 96),
+                (Writable, 64),
+                (Writable, 1),
+                (Writable, 3),
+            ],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        if let Ok(_) = reader.split_at(256) {
+            panic!("successfully split Reader with out of bounds offset");
+        }
+    }
+
+    #[test]
+    fn read_full() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Readable, 16), (Readable, 16), (Readable, 16)],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut reader = Reader::new(&memory, chain).expect("failed to create Reader");
+
+        let mut buf = vec![0u8; 64];
+        assert_eq!(
+            reader.read(&mut buf[..]).expect("failed to read to buffer"),
+            48
+        );
+    }
+
+    #[test]
+    fn write_full() {
+        use DescriptorType::*;
+
+        let memory_start_addr = GuestAddress(0x0);
+        let memory = GuestMemoryMmap::new(&vec![(memory_start_addr, 0x10000)]).unwrap();
+
+        let chain = create_descriptor_chain(
+            &memory,
+            GuestAddress(0x0),
+            GuestAddress(0x100),
+            vec![(Writable, 16), (Writable, 16), (Writable, 16)],
+            0,
+        )
+        .expect("create_descriptor_chain failed");
+        let mut writer = Writer::new(&memory, chain).expect("failed to create Writer");
+
+        let buf = vec![0xdeu8; 64];
+        assert_eq!(
+            writer.write(&buf[..]).expect("failed to write from buffer"),
+            48
+        );
+    }
+}
diff --git a/vhost_user_fs/src/lib.rs b/vhost_user_fs/src/lib.rs
index ce0549bb8..1f11ff546 100644
--- a/vhost_user_fs/src/lib.rs
+++ b/vhost_user_fs/src/lib.rs
@@ -5,6 +5,7 @@
 #[macro_use]
 extern crate log;
 
+pub mod descriptor_utils;
 pub mod file_traits;
 pub mod filesystem;
 pub mod fuse;