diff --git a/Cargo.lock b/Cargo.lock
index 135cfbd..8880cd5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -108,7 +108,9 @@ dependencies = [
  "cortex-a",
  "error",
  "fdt-rs",
+ "memfs",
  "tock-registers",
+ "vfs",
 ]
 
 [[package]]
@@ -121,6 +123,14 @@ checksum = "7b2f96d100e1cf1929e7719b7edb3b90ab5298072638fccd77be9ce942ecdfce"
 name = "libusr"
 version = "0.1.0"
 
+[[package]]
+name = "memfs"
+version = "0.1.0"
+dependencies = [
+ "error",
+ "vfs",
+]
+
 [[package]]
 name = "memoffset"
 version = "0.5.6"
diff --git a/Cargo.toml b/Cargo.toml
index a379754..c92c1ed 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,6 +10,7 @@ edition = "2018"
 [workspace]
 members = [
     "fs/vfs",
+    "fs/memfs",
     "kernel",
     "libusr",
     "init",
diff --git a/Makefile b/Makefile
index 83253fc..18c42c3 100644
--- a/Makefile
+++ b/Makefile
@@ -60,7 +60,8 @@ all: kernel
 kernel:
 	cd kernel && cargo build $(CARGO_BUILD_OPTS)
 	cd init && cargo build --target=../etc/$(ARCH)-osdev5.json -Z build-std=core,alloc,compiler_builtins
-	cp target/$(ARCH)-osdev5/debug/init $(O)/initrd.img
+	echo "This is a test file" >$(O)/test.txt
+	cd $(O) && tar cf initrd.img test.txt
 ifeq ($(ARCH),aarch64)
 	$(LLVM_BASE)/llvm-strip -o $(O)/kernel.strip $(O)/kernel
 	$(LLVM_BASE)/llvm-size $(O)/kernel.strip
@@ -79,6 +80,10 @@ ifeq ($(MACH),orangepi3)
 		$(O)/uImage
 endif
 
+test:
+	cd fs/vfs && cargo test
+	cd fs/memfs && cargo test
+
 clean:
 	cargo clean
 
diff --git a/fs/memfs/Cargo.toml b/fs/memfs/Cargo.toml
new file mode 100644
index 0000000..d261a18
--- /dev/null
+++ b/fs/memfs/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "memfs"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+vfs = { path = "../vfs" }
+error = { path = "../../error" }
diff --git a/fs/memfs/src/block.rs b/fs/memfs/src/block.rs
new file mode 100644
index 0000000..e02dd6c
--- /dev/null
+++ b/fs/memfs/src/block.rs
@@ -0,0 +1,132 @@
+use core::mem::{size_of, MaybeUninit};
+use core::ops::{Deref, DerefMut};
+use error::Errno;
+
+pub const SIZE: usize = 4096;
+pub const ENTRY_COUNT: usize = SIZE / size_of::<usize>();
+
+// Should be the same as "usize" in layout
+pub struct BlockRef<'a, A: BlockAllocator + Copy> {
+    inner: Option<&'a mut [u8; SIZE]>,
+    alloc: MaybeUninit<A>,
+}
+
+pub unsafe trait BlockAllocator {
+    fn alloc(&self) -> *mut u8;
+    unsafe fn dealloc(&self, block: *mut u8);
+}
+
+impl<'a, A: BlockAllocator + Copy> BlockRef<'a, A> {
+    pub fn new(alloc: A) -> Result<Self, Errno> {
+        assert!(size_of::<A>() == 0);
+        let ptr = alloc.alloc();
+        if ptr.is_null() {
+            Err(Errno::OutOfMemory)
+        } else {
+            Ok(unsafe { Self::from_raw(alloc, ptr) })
+        }
+    }
+
+    pub fn new_indirect(alloc: A) -> Result<Self, Errno> {
+        let mut res = Self::new(alloc)?;
+        for it in res.as_mut_ref_array().iter_mut() {
+            it.write(BlockRef::null());
+        }
+        Ok(res)
+    }
+
+    pub const fn null() -> Self {
+        Self {
+            inner: None,
+            alloc: MaybeUninit::uninit(),
+        }
+    }
+
+    pub unsafe fn from_raw(alloc: A, data: *mut u8) -> Self {
+        Self {
+            inner: Some(&mut *(data as *mut _)),
+            alloc: MaybeUninit::new(alloc),
+        }
+    }
+
+    pub const fn is_null(&self) -> bool {
+        self.inner.is_none()
+    }
+
+    pub fn as_mut_ref_array(&mut self) -> &mut [MaybeUninit<BlockRef<'a, A>>; ENTRY_COUNT] {
+        assert_eq!(size_of::<Self>(), 8);
+        unsafe { &mut *(self.deref_mut() as *mut _ as *mut _) }
+    }
+
+    pub fn as_ref_array(&self) -> &[MaybeUninit<BlockRef<'a, A>>; ENTRY_COUNT] {
+        assert_eq!(size_of::<Self>(), 8);
+        unsafe { &*(self.deref() as *const _ as *const _) }
+    }
+}
+
+impl<'a, A: BlockAllocator + Copy> Drop for BlockRef<'a, A> {
+    fn drop(&mut self) {
+        if let Some(inner) = self.inner.take() {
+            unsafe {
+                self.alloc
+                    .assume_init_ref()
+                    .dealloc(inner as *mut _ as *mut _);
+            }
+        }
+    }
+}
+
+impl<'a, A: BlockAllocator + Copy> Deref for BlockRef<'a, A> {
+    type Target = [u8; SIZE];
+
+    fn deref(&self) -> &Self::Target {
+        self.inner.as_ref().unwrap()
+    }
+}
+
+impl<'a, A: BlockAllocator + Copy> DerefMut for BlockRef<'a, A> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.inner.as_mut().unwrap()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::boxed::Box;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    static A_COUNTER: AtomicUsize = AtomicUsize::new(0);
+    #[test]
+    fn block_allocator() {
+        #[derive(Clone, Copy)]
+        struct A;
+        unsafe impl BlockAllocator for A {
+            fn alloc(&self) -> *mut u8 {
+                let b = Box::leak(Box::new([0; SIZE]));
+                A_COUNTER.fetch_add(1, Ordering::SeqCst);
+                b.as_mut_ptr() as *mut _
+            }
+            unsafe fn dealloc(&self, ptr: *mut u8) {
+                A_COUNTER.fetch_sub(1, Ordering::SeqCst);
+                drop(Box::from_raw(ptr as *mut [u8; SIZE]));
+            }
+        }
+        const N: usize = 13;
+        {
+            let mut s: [MaybeUninit<BlockRef<A>>; N] = MaybeUninit::uninit_array();
+            assert_eq!(A_COUNTER.load(Ordering::Acquire), 0);
+            for i in 0..N {
+                let mut block = BlockRef::new(A {}).unwrap();
+                block.fill(1);
+                s[i].write(block);
+            }
+            assert_eq!(A_COUNTER.load(Ordering::Acquire), N);
+            for i in 0..N {
+                unsafe {
+                    s[i].assume_init_drop();
+                }
+            }
+            assert_eq!(A_COUNTER.load(Ordering::Acquire), 0);
+        }
+    }
+}
diff --git a/fs/memfs/src/bvec.rs b/fs/memfs/src/bvec.rs
new file mode 100644
index 0000000..9354953
--- /dev/null
+++ b/fs/memfs/src/bvec.rs
@@ -0,0 +1,611 @@
+use crate::{block, BlockAllocator, BlockRef};
+use core::cmp::{max, min};
+use core::marker::PhantomData;
+use core::mem::MaybeUninit;
+use core::ops::{Index, IndexMut};
+use error::Errno;
+const L0_BLOCKS: usize = 32; // 128K
+const L1_BLOCKS: usize = 8; // 16M
+pub struct Bvec<'a, A: BlockAllocator + Copy> {
+    capacity: usize,
+    size: usize,
+    l0: [MaybeUninit<BlockRef<'a, A>>; L0_BLOCKS],
+    l1: [MaybeUninit<BlockRef<'a, A>>; L1_BLOCKS],
+    l2: MaybeUninit<BlockRef<'a, A>>,
+    alloc: A,
+}
+impl<'a, A: BlockAllocator + Copy> Bvec<'a, A> {
+    pub fn new(alloc: A) -> Self {
+        let mut res = Self {
+            capacity: 0,
+            size: 0,
+            l0: MaybeUninit::uninit_array(),
+            l1: MaybeUninit::uninit_array(),
+            l2: MaybeUninit::uninit(),
+            alloc,
+        };
+        for it in res.l0.iter_mut() {
+            it.write(BlockRef::null());
+        }
+        for it in res.l1.iter_mut() {
+            it.write(BlockRef::null());
+        }
+        res.l2.write(BlockRef::null());
+        res
+    }
+    pub fn resize(&mut self, cap: usize) -> Result<(), Errno> {
+        if cap <= self.capacity {
+            let mut curr = self.capacity;
+            while curr != cap {
+                curr -= 1;
+                let mut index = curr;
+                if index >= L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT {
+                    index -= L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT;
+                    let l1i = index / block::ENTRY_COUNT;
+                    let l0i = index % block::ENTRY_COUNT;
+                    let l2r = unsafe { self.l2.assume_init_mut() };
+                    assert!(!l2r.is_null());
+                    let l1r = unsafe { l2r.as_mut_ref_array()[l1i].assume_init_mut() };
+                    assert!(!l1r.is_null());
+                    let l0r = unsafe { l1r.as_mut_ref_array()[l0i].assume_init_mut() };
+                    assert!(!l0r.is_null());
+                    *l0r = BlockRef::null();
+                    if l0i == 0 {
+                        *l1r = BlockRef::null();
+                    }
+                    if index == 0 {
+                        *l2r = BlockRef::null();
+                    }
+                    continue;
+                }
+                if index >= L0_BLOCKS {
+                    index -= L0_BLOCKS;
+                    let l1i = index / block::ENTRY_COUNT;
+                    let l0i = index % block::ENTRY_COUNT;
+                    let l1r = unsafe { self.l1[l1i].assume_init_mut() };
+                    assert!(!l1r.is_null());
+                    let l0r = unsafe { l1r.as_mut_ref_array()[l0i].assume_init_mut() };
+                    assert!(!l0r.is_null());
+                    *l0r = BlockRef::null();
+                    if l0i == 0 {
+                        *l1r = BlockRef::null();
+                    }
+                    continue;
+                }
+                let l0r = unsafe { self.l0[index].assume_init_mut() };
+                assert!(!l0r.is_null());
+                *l0r = BlockRef::null();
+                continue;
+                unimplemented!();
+            }
+        } else {
+            for mut index in self.capacity..cap {
+                if index < L0_BLOCKS {
+                    let l0r = unsafe { self.l0[index].assume_init_mut() };
+                    assert!(l0r.is_null());
+                    *l0r = BlockRef::new(self.alloc)?;
+                    continue;
+                }
+                index -= L0_BLOCKS;
+                if index < L1_BLOCKS * block::ENTRY_COUNT {
+                    let l1i = index / block::ENTRY_COUNT;
+                    let l0i = index % block::ENTRY_COUNT;
+                    let l1r = unsafe { self.l1[l1i].assume_init_mut() };
+                    if l1r.is_null() {
+                        *l1r = BlockRef::new_indirect(self.alloc)?;
+                    }
+                    let l0r = unsafe { l1r.as_mut_ref_array()[l0i].assume_init_mut() };
+                    assert!(l0r.is_null());
+                    *l0r = BlockRef::new(self.alloc)?;
+                    continue;
+                }
+                index -= L1_BLOCKS * block::ENTRY_COUNT;
+                if index < block::ENTRY_COUNT * block::ENTRY_COUNT {
+                    let l1i = index / block::ENTRY_COUNT;
+                    let l0i = index % block::ENTRY_COUNT;
+                    let l2r = unsafe { self.l2.assume_init_mut() };
+                    if l2r.is_null() {
+                        *l2r = BlockRef::new_indirect(self.alloc)?;
+                    }
+                    let l1r = unsafe { l2r.as_mut_ref_array()[l1i].assume_init_mut() };
+                    if l1r.is_null() {
+                        *l1r = BlockRef::new_indirect(self.alloc)?;
+                    }
+                    let l0r = unsafe { l1r.as_mut_ref_array()[l0i].assume_init_mut() };
+                    assert!(l0r.is_null());
+                    *l0r = BlockRef::new(self.alloc)?;
+                    continue;
+                }
+                unimplemented!();
+            }
+        }
+        self.capacity = cap;
+        Ok(())
+    }
+    pub fn write(&mut self, mut pos: usize, data: &[u8]) -> Result<usize, Errno> {
+        if pos > self.size {
+            return Err(Errno::InvalidArgument);
+        }
+        let mut rem = data.len();
+        let mut doff = 0usize;
+        if pos + rem > self.size {
+            self.size = pos + rem;
+            self.resize((pos + rem + block::SIZE - 1) / block::SIZE)?;
+        }
+        while rem > 0 {
+            let index = pos / block::SIZE;
+            let off = pos % block::SIZE;
+            let count = min(block::SIZE - off, rem);
+            let block = &mut self[index];
+            let dst = &mut block[off..off + count];
+            let src = &data[doff..doff + count];
+            dst.copy_from_slice(src);
+            doff += count;
+            pos += count;
+            rem -= count;
+        }
+        Ok(doff)
+    }
+    pub fn read(&self, mut pos: usize, data: &mut [u8]) -> Result<usize, Errno> {
+        if pos > self.size {
+            return Err(Errno::InvalidArgument);
+        }
+        let mut rem = min(self.size - pos, data.len());
+        let mut doff = 0usize;
+        while rem > 0 {
+            let index = pos / block::SIZE;
+            let off = pos % block::SIZE;
+            let count = min(block::SIZE - off, rem);
+            let block = &self[index];
+            let src = &block[off..off + count];
+            let dst = &mut data[doff..doff + count];
+            dst.copy_from_slice(src);
+            doff += count;
+            pos += count;
+            rem -= count;
+        }
+        Ok(doff)
+    }
+}
+impl<'a, A: BlockAllocator + Copy> Index<usize> for Bvec<'a, A> {
+    type Output = BlockRef<'a, A>;
+    fn index(&self, mut index: usize) -> &Self::Output {
+        if index >= self.capacity {
+            panic!(
+                "Index exceeds bvec capacity ({} >= {})",
+                index, self.capacity
+            );
+        }
+        if index < L0_BLOCKS {
+            return unsafe { self.l0[index].assume_init_ref() };
+        }
+        index -= L0_BLOCKS;
+        if index < L1_BLOCKS * block::ENTRY_COUNT {
+            return unsafe {
+                let l1 = self.l1[index / block::ENTRY_COUNT].assume_init_ref();
+                l1.as_ref_array()[index % block::ENTRY_COUNT].assume_init_ref()
+            };
+        }
+        index -= L1_BLOCKS * block::ENTRY_COUNT;
+        if index < block::ENTRY_COUNT * block::ENTRY_COUNT {
+            return unsafe {
+                let l2 = self.l2.assume_init_ref();
+                let l1 = l2.as_ref_array()[index / block::ENTRY_COUNT].assume_init_ref();
+                l1.as_ref_array()[index % block::ENTRY_COUNT].assume_init_ref()
+            };
+        }
+        unimplemented!();
+    }
+}
+impl<'a, A: BlockAllocator + Copy> IndexMut<usize> for Bvec<'a, A> {
+    fn index_mut(&mut self, mut index: usize) -> &mut Self::Output {
+        if index >= self.capacity {
+            panic!(
+                "Index exceeds bvec capacity ({} >= {})",
+                index, self.capacity
+            );
+        }
+        if index < L0_BLOCKS {
+            return unsafe { self.l0[index].assume_init_mut() };
+        }
+        index -= L0_BLOCKS;
+        if index < L1_BLOCKS * block::ENTRY_COUNT {
+            return unsafe {
+                let l1 = self.l1[index / block::ENTRY_COUNT].assume_init_mut();
+                l1.as_mut_ref_array()[index % block::ENTRY_COUNT].assume_init_mut()
+            };
+        }
+        index -= L1_BLOCKS * block::ENTRY_COUNT;
+        if index < block::ENTRY_COUNT * block::ENTRY_COUNT {
+            return unsafe {
+                let l2 = self.l2.assume_init_mut();
+                let l1 = l2.as_mut_ref_array()[index / block::ENTRY_COUNT].assume_init_mut();
+                l1.as_mut_ref_array()[index % block::ENTRY_COUNT].assume_init_mut()
+            };
+        }
+        unimplemented!();
+    }
+}
+impl<'a, A: BlockAllocator + Copy> Drop for Bvec<'a, A> {
+    fn drop(&mut self) {
+        for i in 0..min(L0_BLOCKS, self.capacity) {
+            unsafe {
+                self.l0[i].assume_init_drop();
+            }
+        }
+        if self.capacity > L0_BLOCKS {}
+    }
+}
+
+#[cfg(feature = "test_bvec")]
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::boxed::Box;
+    use std::mem::MaybeUninit;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    static A_COUNTER: AtomicUsize = AtomicUsize::new(0);
+    #[derive(Clone, Copy)]
+    struct TestAlloc;
+    unsafe impl BlockAllocator for TestAlloc {
+        fn alloc(&self) -> *mut u8 {
+            let b = Box::leak(Box::new([0; block::SIZE]));
+            eprintln!("alloc {:p}", b);
+            b.as_mut_ptr() as *mut _
+        }
+        unsafe fn dealloc(&self, ptr: *mut u8) {
+            eprintln!("drop {:p}", ptr);
+            drop(Box::from_raw(ptr as *mut [u8; block::SIZE]));
+        }
+    }
+    #[test]
+    fn bvec_allocation() {
+        #[derive(Clone, Copy)]
+        struct A;
+        unsafe impl BlockAllocator for A {
+            fn alloc(&self) -> *mut u8 {
+                let b = Box::leak(Box::new([0; block::SIZE]));
+                A_COUNTER.fetch_add(1, Ordering::SeqCst);
+                b.as_mut_ptr() as *mut _
+            }
+            unsafe fn dealloc(&self, ptr: *mut u8) {
+                A_COUNTER.fetch_sub(1, Ordering::SeqCst);
+                drop(Box::from_raw(ptr as *mut [u8; block::SIZE]));
+            }
+        }
+        let mut bvec = Bvec::new(A {});
+        assert_eq!(A_COUNTER.load(Ordering::Acquire), 0);
+        bvec.resize(123).unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            let l1r = bvec.l1[0].assume_init_ref();
+            assert!(!l1r.is_null());
+            for i in 0..123 - L0_BLOCKS {
+                assert!(!l1r.as_ref_array()[i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(A_COUNTER.load(Ordering::Acquire), 123 + 1);
+        bvec.resize(123 + block::ENTRY_COUNT).unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..(123 + block::ENTRY_COUNT) - L0_BLOCKS {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            123 + block::ENTRY_COUNT + 2
+        );
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT)
+            .unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..L1_BLOCKS * block::ENTRY_COUNT {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + L1_BLOCKS
+        );
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 4)
+            .unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..L1_BLOCKS * block::ENTRY_COUNT {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+            let l2r = bvec.l2.assume_init_ref();
+            assert!(!l2r.is_null());
+            for i in 0..block::ENTRY_COUNT * 4 {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = l2r.as_ref_array()[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + // L0
+            L1_BLOCKS * block::ENTRY_COUNT + L1_BLOCKS + // L1
+            block::ENTRY_COUNT * 4 + 4 + 1
+        );
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 3 + 1)
+            .unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..L1_BLOCKS * block::ENTRY_COUNT {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+            let l2r = bvec.l2.assume_init_ref();
+            assert!(!l2r.is_null());
+            for i in 0..block::ENTRY_COUNT * 3 + 1 {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = l2r.as_ref_array()[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + // L0
+            L1_BLOCKS * block::ENTRY_COUNT + L1_BLOCKS + // L1
+            block::ENTRY_COUNT * 3 + 1 + 4 + 1
+        );
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 2 + 1)
+            .unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..L1_BLOCKS * block::ENTRY_COUNT {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+            let l2r = bvec.l2.assume_init_ref();
+            assert!(!l2r.is_null());
+            for i in 0..block::ENTRY_COUNT * 2 + 1 {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = l2r.as_ref_array()[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + // L0
+            L1_BLOCKS * block::ENTRY_COUNT + L1_BLOCKS + // L1
+            block::ENTRY_COUNT * 2 + 1 + 3 + 1
+        );
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 1)
+            .unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..L1_BLOCKS * block::ENTRY_COUNT {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+            let l2r = bvec.l2.assume_init_ref();
+            assert!(!l2r.is_null());
+            let l1r = l2r.as_ref_array()[0].assume_init_ref();
+            assert!(!l1r.is_null());
+            assert!(!l1r.as_ref_array()[0].assume_init_ref().is_null());
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + // L0
+            L1_BLOCKS * block::ENTRY_COUNT + L1_BLOCKS + // L1
+            1 + 1 + 1
+        );
+        bvec.resize(L0_BLOCKS + 3 * block::ENTRY_COUNT + 1).unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            for i in 0..3 * block::ENTRY_COUNT + 1 {
+                let l1i = i / block::ENTRY_COUNT;
+                let l0i = i % block::ENTRY_COUNT;
+                let l1r = bvec.l1[l1i].assume_init_ref();
+                assert!(!l1r.is_null());
+                assert!(!l1r.as_ref_array()[l0i].assume_init_ref().is_null());
+            }
+            let l2r = bvec.l2.assume_init_ref();
+            assert!(l2r.is_null());
+        }
+        assert_eq!(
+            A_COUNTER.load(Ordering::Acquire),
+            L0_BLOCKS + // L0
+            3 * block::ENTRY_COUNT + 1 + 4
+        );
+        bvec.resize(L0_BLOCKS).unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+            assert!(bvec.l1[0].assume_init_ref().is_null());
+        }
+        assert_eq!(A_COUNTER.load(Ordering::Acquire), L0_BLOCKS);
+        bvec.resize(12).unwrap();
+        unsafe {
+            for i in 0..12 {
+                assert!(!bvec.l0[i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(A_COUNTER.load(Ordering::Acquire), 12);
+        bvec.resize(0).unwrap();
+        unsafe {
+            for i in 0..L0_BLOCKS {
+                assert!(bvec.l0[i].assume_init_ref().is_null());
+            }
+        }
+        assert_eq!(A_COUNTER.load(Ordering::Acquire), 0);
+    }
+    #[test]
+    fn bvec_index_l0() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS).unwrap();
+        for i in 0..L0_BLOCKS {
+            let block = &bvec[i];
+            assert_eq!(block as *const _, bvec.l0[i].as_ptr());
+        }
+    }
+    #[test]
+    fn bvec_index_l1() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + block::ENTRY_COUNT * 2 + 3).unwrap();
+        for i in 0..block::ENTRY_COUNT * 2 + 3 {
+            let l1i = i / block::ENTRY_COUNT;
+            let l0i = i % block::ENTRY_COUNT;
+            let block = &bvec[i + L0_BLOCKS];
+            let l1r = unsafe { bvec.l1[l1i].assume_init_ref() };
+            assert_eq!(block as *const _, l1r.as_ref_array()[l0i].as_ptr());
+        }
+    }
+    #[test]
+    fn bvec_index_l2() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 3)
+            .unwrap();
+        for i in 0..3 {
+            let l1i = i / block::ENTRY_COUNT;
+            let l0i = i % block::ENTRY_COUNT;
+            let block = &bvec[i + L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT];
+            let l2r = unsafe { bvec.l2.assume_init_ref() };
+            let l1r = unsafe { l2r.as_ref_array()[l1i].assume_init_ref() };
+            assert_eq!(block as *const _, l1r.as_ref_array()[l0i].as_ptr());
+        }
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l0_0() {
+        let bvec = Bvec::new(TestAlloc {});
+        let _block = &bvec[0];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l0_1() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(13).unwrap();
+        let _block = &bvec[15];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l1_0() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(13).unwrap();
+        let _block = &bvec[L0_BLOCKS + 2];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l1_1() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + block::ENTRY_COUNT * 2 + 3).unwrap();
+        let _block = &bvec[L0_BLOCKS + block::ENTRY_COUNT * 2 + 6];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l1_2() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + block::ENTRY_COUNT * 2 + 3).unwrap();
+        let _block = &bvec[L0_BLOCKS + block::ENTRY_COUNT * 3 + 1];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l2_0() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(13).unwrap();
+        let _block = &bvec[L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 3];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l2_1() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + block::ENTRY_COUNT * 3 + 13)
+            .unwrap();
+        let _block = &bvec[L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 3];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l2_2() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 6)
+            .unwrap();
+        let _block = &bvec[L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 8];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l2_3() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 2 + 7)
+            .unwrap();
+        let _block =
+            &bvec[L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 2 + 13];
+    }
+    #[test]
+    #[should_panic]
+    fn bvec_index_invalid_l2_4() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        bvec.resize(L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 2 + 13)
+            .unwrap();
+        let _block = &bvec[L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + block::ENTRY_COUNT * 3 + 2];
+    }
+    #[test]
+    fn bvec_write_read() {
+        let mut bvec = Bvec::new(TestAlloc {});
+        const N: usize = block::SIZE * (L0_BLOCKS + L1_BLOCKS * block::ENTRY_COUNT + 3);
+        let mut data = vec![0u8; N];
+        for i in 0..N {
+            data[i] = (i & 0xFF) as u8;
+        }
+        assert_eq!(bvec.write(0, &data[..]), Ok(N));
+        let mut buf = vec![0u8; 327];
+        let mut off = 0usize;
+        let mut rem = N;
+        while rem != 0 {
+            let count = min(rem, buf.len());
+            assert_eq!(bvec.read(off, &mut buf[..]), Ok(count));
+            for i in 0..count {
+                assert_eq!(buf[i], ((i + off) & 0xFF) as u8);
+            }
+            rem -= count;
+            off += count;
+        }
+    }
+}
diff --git a/fs/memfs/src/lib.rs b/fs/memfs/src/lib.rs
new file mode 100644
index 0000000..5529fb6
--- /dev/null
+++ b/fs/memfs/src/lib.rs
@@ -0,0 +1,237 @@
+#![feature(
+    const_fn_trait_bound,
+    const_mut_refs,
+    maybe_uninit_extra,
+    maybe_uninit_uninit_array
+)]
+#![no_std]
+
+extern crate alloc;
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
+use alloc::{boxed::Box, rc::Rc};
+use core::cell::RefCell;
+use error::Errno;
+use vfs::{node::VnodeData, Filesystem, Vnode, VnodeImpl, VnodeKind, VnodeRef};
+
+pub mod block;
+pub use block::{BlockAllocator, BlockRef};
+pub mod bvec;
+use bvec::Bvec;
+pub mod tar;
+use tar::{Tar, TarIterator};
+
+pub struct Ramfs<A: BlockAllocator + Copy + 'static> {
+    root: RefCell<Option<VnodeRef>>,
+    alloc: A,
+}
+
+pub struct FileInode<'a, A: BlockAllocator + Copy + 'static> {
+    data: Bvec<'a, A>,
+}
+
+pub struct DirInode;
+
+impl<'a, A: BlockAllocator + Copy + 'static> VnodeImpl for FileInode<'a, A> {
+    fn create(&mut self, _parent: VnodeRef, _node: VnodeRef) -> Result<(), Errno> {
+        panic!()
+    }
+
+    fn remove(&mut self, _parent: VnodeRef, _name: &str) -> Result<(), Errno> {
+        panic!()
+    }
+
+    fn open(&mut self, node: VnodeRef) -> Result<usize, Errno> {
+        Ok(0)
+    }
+
+    fn close(&mut self, node: VnodeRef) -> Result<(), Errno> {
+        Ok(())
+    }
+
+    fn read(&mut self, node: VnodeRef, pos: usize, data: &mut [u8]) -> Result<usize, Errno> {
+        self.data.read(pos, data)
+    }
+
+    fn write(&mut self, node: VnodeRef, pos: usize, data: &[u8]) -> Result<usize, Errno> {
+        self.data.write(pos, data)
+    }
+
+    fn truncate(&mut self, _node: VnodeRef, size: usize) -> Result<(), Errno> {
+        self.data.resize((size + 4095) / 4096)
+    }
+}
+
+impl VnodeImpl for DirInode {
+    fn create(&mut self, _parent: VnodeRef, _node: VnodeRef) -> Result<(), Errno> {
+        Ok(())
+    }
+
+    fn remove(&mut self, _parent: VnodeRef, _name: &str) -> Result<(), Errno> {
+        Ok(())
+    }
+
+    fn open(&mut self, node: VnodeRef) -> Result<usize, Errno> {
+        todo!()
+    }
+
+    fn close(&mut self, node: VnodeRef) -> Result<(), Errno> {
+        todo!()
+    }
+
+    fn read(&mut self, node: VnodeRef, pos: usize, data: &mut [u8]) -> Result<usize, Errno> {
+        todo!()
+    }
+
+    fn write(&mut self, node: VnodeRef, pos: usize, data: &[u8]) -> Result<usize, Errno> {
+        todo!()
+    }
+
+    fn truncate(&mut self, _node: VnodeRef, _size: usize) -> Result<(), Errno> {
+        todo!()
+    }
+}
+
+impl<A: BlockAllocator + Copy + 'static> Filesystem for Ramfs<A> {
+    fn root(self: Rc<Self>) -> Result<VnodeRef, Errno> {
+        self.root.borrow().clone().ok_or(Errno::DoesNotExist)
+    }
+
+    fn create_node(self: Rc<Self>, name: &str, kind: VnodeKind) -> Result<VnodeRef, Errno> {
+        let mut node = Vnode::new(name, kind);
+        let data: Box<dyn VnodeImpl> = match kind {
+            VnodeKind::Regular => Box::new(FileInode {
+                data: Bvec::new(self.alloc),
+            }),
+            VnodeKind::Directory => Box::new(DirInode {}),
+        };
+        node.set_data(VnodeData {
+            fs: self,
+            node: data,
+        });
+        Ok(node)
+    }
+}
+
+impl<A: BlockAllocator + Copy + 'static> Ramfs<A> {
+    pub fn open(base: *const u8, size: usize, alloc: A) -> Result<Rc<Self>, Errno> {
+        let mut res = Rc::new(Self {
+            root: RefCell::new(None),
+            alloc,
+        });
+        unsafe {
+            *res.root.borrow_mut() = Some(res.clone().load_tar(base, size)?);
+        }
+        Ok(res)
+    }
+
+    fn make_path(
+        self: Rc<Self>,
+        at: VnodeRef,
+        path: &str,
+        kind: VnodeKind,
+        do_create: bool,
+    ) -> Result<VnodeRef, Errno> {
+        let (element, rest) = vfs::util::path_component_left(path);
+        assert!(!element.is_empty());
+
+        let node_kind = if rest.is_empty() {
+            kind
+        } else {
+            VnodeKind::Directory
+        };
+
+        let node = at.lookup(element);
+        let node = match node {
+            Some(node) => node,
+            None => {
+                if !do_create {
+                    return Err(Errno::DoesNotExist);
+                }
+                let node = self.clone().create_node(element, node_kind)?;
+                at.attach(node.clone());
+                node
+            }
+        };
+
+        if rest.is_empty() {
+            Ok(node)
+        } else {
+            self.make_path(node, rest, kind, do_create)
+        }
+    }
+
+    unsafe fn load_tar(self: Rc<Self>, base: *const u8, size: usize) -> Result<VnodeRef, Errno> {
+        let root = self.clone().create_node("", VnodeKind::Directory)?;
+
+        // 1. Create all the paths in TAR
+        for block in TarIterator::new(base, base.add(size)) {
+            let node =
+                self.clone()
+                    .make_path(root.clone(), block.path()?, block.node_kind(), true)?;
+            assert_eq!(node.kind(), block.node_kind());
+        }
+
+        // 2. Setup data blocks
+        for block in TarIterator::new(base, base.add(size)) {
+            if block.is_file() {
+                let size = block.size();
+                let node = self.clone().make_path(
+                    root.clone(),
+                    block.path()?,
+                    block.node_kind(),
+                    false,
+                )?;
+
+                node.truncate(size).unwrap();
+                let res = node.write(0, block.data()).unwrap();
+                if res != size {
+                    panic!("Expected to write {}B, got {}B", size, res);
+                }
+            }
+        }
+
+        Ok(root)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use alloc::boxed::Box;
+    use vfs::Ioctx;
+
+    #[test]
+    fn ramfs_open() {
+        #[derive(Clone, Copy)]
+        struct A;
+        unsafe impl BlockAllocator for A {
+            fn alloc(&self) -> *mut u8 {
+                let b = Box::leak(Box::new([0; block::SIZE]));
+                b.as_mut_ptr() as *mut _
+            }
+            unsafe fn dealloc(&self, ptr: *mut u8) {
+                drop(Box::from_raw(ptr as *mut [u8; block::SIZE]));
+            }
+        }
+        unsafe impl Sync for A {}
+
+        let data = include_str!("../test/test1.tar");
+        let fs = Ramfs::open(data.as_ptr(), data.bytes().len(), A {}).unwrap();
+
+        let root = fs.root().unwrap();
+        let ioctx = Ioctx::new(root.clone());
+
+        assert!(Rc::ptr_eq(&ioctx.find(None, "/").unwrap(), &root));
+
+        let node = ioctx.find(None, "/test1.txt").unwrap();
+        let mut file = node.open().unwrap();
+        let mut buf = [0u8; 1024];
+
+        assert_eq!(file.read(&mut buf).unwrap(), 20);
+        let s = core::str::from_utf8(&buf[..20]).unwrap();
+        assert_eq!(s, "This is a test file\n");
+    }
+}
diff --git a/fs/memfs/src/tar.rs b/fs/memfs/src/tar.rs
new file mode 100644
index 0000000..79419b2
--- /dev/null
+++ b/fs/memfs/src/tar.rs
@@ -0,0 +1,112 @@
+use vfs::VnodeKind;
+use error::Errno;
+
+#[repr(packed)]
+#[allow(dead_code)]
+pub struct Tar {
+    name: [u8; 100],
+    mode: [u8; 8],
+    uid: [u8; 8],
+    gid: [u8; 8],
+    size: [u8; 12],
+    mtime: [u8; 12],
+    checksum: [u8; 8],
+    type_: u8,
+    link_name: [u8; 100],
+    magic: [u8; 8],
+    user: [u8; 32],
+    group: [u8; 32],
+    dev_major: [u8; 8],
+    dev_minor: [u8; 8],
+    prefix: [u8; 155],
+}
+
+pub struct TarIterator {
+    address: *const u8,
+    limit: *const u8,
+    zero_blocks: usize,
+}
+
+impl TarIterator {
+    pub const fn new(
+        address: *const u8,
+        limit: *const u8,
+    ) -> Self {
+        Self {
+            address,
+            limit,
+            zero_blocks: 0,
+        }
+    }
+}
+
+impl Iterator for TarIterator {
+    type Item = &'static Tar;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.address >= self.limit || self.zero_blocks == 2 {
+            return None;
+        }
+
+        let bytes: &[u8; 512] = unsafe { (self.address as *const [u8; 512]).as_ref() }.unwrap();
+        if bytes.iter().all(|&x| x == 0) {
+            self.zero_blocks += 1;
+            self.address = unsafe { self.address.add(512) };
+            self.next()
+        } else {
+            let block: &Tar = unsafe { (self.address as *const Tar).as_ref() }.unwrap();
+            self.zero_blocks = 0;
+            self.address = unsafe { self.address.add(512 + align_up(block.size())) };
+            Some(block)
+        }
+    }
+}
+
+impl Tar {
+    pub fn is_file(&self) -> bool {
+        self.type_ == 0 || self.type_ == b'0'
+    }
+
+    pub fn size(&self) -> usize {
+        from_octal(&self.size)
+    }
+
+    pub fn path(&self) -> Result<&str, Errno> {
+        let zero_index = self.name.iter().position(|&c| c == 0).unwrap();
+        core::str::from_utf8(&self.name[..zero_index]).map_err(|_| Errno::InvalidArgument)
+    }
+
+    pub fn node_kind(&self) -> VnodeKind {
+        match self.type_ {
+            0 | b'0' => VnodeKind::Regular,
+            b'5' => VnodeKind::Directory,
+            p => panic!("Unrecognized tar entry type: '{}'", p as char),
+        }
+    }
+
+    pub fn data(&self) -> &[u8] {
+        unsafe {
+            core::slice::from_raw_parts(
+                ((self as *const _ as usize) + 512) as *const _,
+                self.size(),
+            )
+        }
+    }
+}
+
+fn from_octal(oct: &[u8]) -> usize {
+    let mut res = 0usize;
+    for &byte in oct {
+        if byte == 0 {
+            break;
+        }
+
+        res <<= 3;
+        res |= (byte - b'0') as usize;
+    }
+    res
+}
+
+const fn align_up(size: usize) -> usize {
+    (size + 511) & !511
+}
diff --git a/fs/memfs/test/test1.tar b/fs/memfs/test/test1.tar
new file mode 100644
index 0000000..b2f0f32
Binary files /dev/null and b/fs/memfs/test/test1.tar differ
diff --git a/fs/memfs/test/test1.txt b/fs/memfs/test/test1.txt
new file mode 100644
index 0000000..9f4b6d8
--- /dev/null
+++ b/fs/memfs/test/test1.txt
@@ -0,0 +1 @@
+This is a test file
diff --git a/fs/vfs/src/file.rs b/fs/vfs/src/file.rs
index 4388275..1fb1374 100644
--- a/fs/vfs/src/file.rs
+++ b/fs/vfs/src/file.rs
@@ -76,6 +76,10 @@ mod tests {
         fn write(&mut self, _node: VnodeRef, _pos: usize, _data: &[u8]) -> Result<usize, Errno> {
             Err(Errno::NotImplemented)
         }
+
+        fn truncate(&mut self, _node: VnodeRef, _size: usize) -> Result<(), Errno> {
+            Err(Errno::NotImplemented)
+        }
     }
 
     impl Filesystem for DummyFs {
diff --git a/fs/vfs/src/ioctx.rs b/fs/vfs/src/ioctx.rs
index eca7810..672d549 100644
--- a/fs/vfs/src/ioctx.rs
+++ b/fs/vfs/src/ioctx.rs
@@ -102,6 +102,10 @@ mod tests {
         fn write(&mut self, _node: VnodeRef, _pos: usize, _data: &[u8]) -> Result<usize, Errno> {
             Err(Errno::NotImplemented)
         }
+
+        fn truncate(&mut self, _node: VnodeRef, _size: usize) -> Result<(), Errno> {
+            Err(Errno::NotImplemented)
+        }
     }
 
     impl Filesystem for DummyFs {
diff --git a/fs/vfs/src/node.rs b/fs/vfs/src/node.rs
index bb886d8..70d4c69 100644
--- a/fs/vfs/src/node.rs
+++ b/fs/vfs/src/node.rs
@@ -45,6 +45,7 @@ pub trait VnodeImpl {
     fn open(&mut self, node: VnodeRef /* TODO open mode */) -> Result<usize, Errno>;
     fn close(&mut self, node: VnodeRef) -> Result<(), Errno>;
 
+    fn truncate(&mut self, node: VnodeRef, size: usize) -> Result<(), Errno>;
     fn read(&mut self, node: VnodeRef, pos: usize, data: &mut [u8]) -> Result<usize, Errno>;
     fn write(&mut self, node: VnodeRef, pos: usize, data: &[u8]) -> Result<usize, Errno>;
 }
@@ -77,6 +78,11 @@ impl Vnode {
         self.kind == VnodeKind::Directory
     }
 
+    #[inline(always)]
+    pub const fn kind(&self) -> VnodeKind {
+        self.kind
+    }
+
     // Tree operations
 
     pub fn attach(self: &VnodeRef, child: VnodeRef) {
@@ -188,6 +194,30 @@ impl Vnode {
             Err(Errno::NotImplemented)
         }
     }
+
+    pub fn write(self: &VnodeRef, pos: usize, buf: &[u8]) -> Result<usize, Errno> {
+        if self.kind != VnodeKind::Regular {
+            return Err(Errno::IsADirectory);
+        }
+
+        if let Some(ref mut data) = *self.data.borrow_mut() {
+            data.node.write(self.clone(), pos, buf)
+        } else {
+            Err(Errno::NotImplemented)
+        }
+    }
+
+    pub fn truncate(self: &VnodeRef, size: usize) -> Result<(), Errno> {
+        if self.kind != VnodeKind::Regular {
+            return Err(Errno::IsADirectory);
+        }
+
+        if let Some(ref mut data) = *self.data.borrow_mut() {
+            data.node.truncate(self.clone(), size)
+        } else {
+            Err(Errno::NotImplemented)
+        }
+    }
 }
 
 impl fmt::Debug for Vnode {
@@ -228,6 +258,10 @@ mod tests {
         fn write(&mut self, _node: VnodeRef, _pos: usize, _data: &[u8]) -> Result<usize, Errno> {
             Err(Errno::NotImplemented)
         }
+
+        fn truncate(&mut self, _node: VnodeRef, _size: usize) -> Result<(), Errno> {
+            Err(Errno::NotImplemented)
+        }
     }
 
     impl Filesystem for DummyFs {
diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index 8204965..b506e17 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -11,6 +11,8 @@ test = false
 
 [dependencies]
 error = { path = "../error" }
+vfs = { path = "../fs/vfs" }
+memfs = { path = "../fs/memfs" }
 cfg-if = "1.x.x"
 tock-registers = "0.7.x"
 fdt-rs = { version = "0.x.x", default-features = false }
diff --git a/kernel/src/fs/mod.rs b/kernel/src/fs/mod.rs
new file mode 100644
index 0000000..0094ea8
--- /dev/null
+++ b/kernel/src/fs/mod.rs
@@ -0,0 +1,21 @@
+#![allow(missing_docs)]
+
+use crate::mem::{self, phys::{self, PageUsage}};
+use memfs::BlockAllocator;
+
+#[derive(Clone, Copy)]
+pub struct MemfsBlockAlloc;
+
+unsafe impl BlockAllocator for MemfsBlockAlloc {
+    fn alloc(&self) -> *mut u8 {
+        if let Ok(page) = phys::alloc_page(PageUsage::Kernel) {
+            mem::virtualize(page) as *mut u8
+        } else {
+            core::ptr::null_mut()
+        }
+    }
+
+    unsafe fn dealloc(&self, data: *mut u8) {
+        todo!()
+    }
+}
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index 853d519..8610548 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -10,7 +10,7 @@
     const_panic,
     panic_info_message,
     alloc_error_handler,
-    const_btree_new,
+    const_btree_new
 )]
 #![no_std]
 #![no_main]
@@ -27,12 +27,13 @@ pub mod debug;
 
 pub mod arch;
 pub mod dev;
+pub mod fs;
 pub mod mem;
 pub mod proc;
 pub mod sync;
-pub mod util;
 #[allow(missing_docs)]
 pub mod syscall;
+pub mod util;
 
 #[panic_handler]
 fn panic_handler(pi: &core::panic::PanicInfo) -> ! {
diff --git a/kernel/src/proc/mod.rs b/kernel/src/proc/mod.rs
index 5962ca8..0399c49 100644
--- a/kernel/src/proc/mod.rs
+++ b/kernel/src/proc/mod.rs
@@ -57,15 +57,31 @@ pub unsafe fn enter(initrd: Option<(usize, usize)>) -> ! {
     if let Some((start, end)) = initrd {
         let initrd = Box::into_raw(Box::new((mem::virtualize(start), mem::virtualize(end))));
 
-        for _ in 0..4 {
-            spawn!(fn (initrd_ptr: usize) {
-                debugln!("Running kernel init process");
+        spawn!(fn (initrd_ptr: usize) {
+            use memfs::Ramfs;
+            use vfs::{Filesystem, Ioctx};
+            use crate::fs::MemfsBlockAlloc;
+            debugln!("Running kernel init process");
 
-                let (start, _end) = unsafe { *(initrd_ptr as *const (usize, usize)) };
-                Process::execve(|space| elf::load_elf(space, start as *const u8), 0).unwrap();
-                panic!("This code should not run");
-            }, initrd as usize);
-        }
+            let (start, end) = unsafe { *(initrd_ptr as *const (usize, usize)) };
+            let size = end - start;
+
+            let fs = Ramfs::open(start as *mut u8, size, MemfsBlockAlloc {}).unwrap();
+            let root = fs.root().unwrap();
+            let ioctx = Ioctx::new(root);
+
+            // Open a test file
+            let node = ioctx.find(None, "/test.txt").unwrap();
+            let mut file = node.open().unwrap();
+            let mut buf = [0u8; 16];
+
+            while let Ok(count) = file.read(&mut buf) {
+                if count == 0 {
+                    break;
+                }
+                debugln!("Read {} bytes: {:?}", count, &buf[0..count]);
+            }
+        }, initrd as usize);
     }
     SCHED.enter();
 }