diff --git a/easy-fs/.gitignore b/easy-fs/.gitignore
new file mode 100644
index 00000000..79f5db68
--- /dev/null
+++ b/easy-fs/.gitignore
@@ -0,0 +1,3 @@
+.idea/
+target/
+Cargo.lock
diff --git a/easy-fs/Cargo.toml b/easy-fs/Cargo.toml
new file mode 100644
index 00000000..b441f2a1
--- /dev/null
+++ b/easy-fs/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "easy-fs"
+version = "0.1.0"
+authors = ["Yifan Wu <shinbokuow@163.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/easy-fs/src/bin/main.rs b/easy-fs/src/bin/main.rs
new file mode 100644
index 00000000..f25aec75
--- /dev/null
+++ b/easy-fs/src/bin/main.rs
@@ -0,0 +1,53 @@
+extern crate easy_fs;
+extern crate alloc;
+
+use easy_fs::{
+    BlockDevice,
+    EasyFileSystem,
+};
+use std::fs::{File, OpenOptions};
+use std::io::{Read, Write, Seek, SeekFrom};
+use std::sync::Mutex;
+use alloc::sync::Arc;
+
+const BLOCK_SZ: usize = 512;
+
+struct BlockFile(Mutex<File>);
+
+impl BlockDevice for BlockFile {
+    fn read_block(&self, block_id: usize, buf: &mut [u8]) {
+        let mut file = self.0.lock().unwrap();
+        file.seek(SeekFrom::Start((block_id * BLOCK_SZ) as u64))
+            .expect("Error when seeking!");
+        assert_eq!(file.read(buf).unwrap(), BLOCK_SZ, "Not a complete block!");
+    }
+
+    fn write_block(&self, block_id: usize, buf: &[u8]) {
+        let mut file = self.0.lock().unwrap();
+        file.seek(SeekFrom::Start((block_id * BLOCK_SZ) as u64))
+            .expect("Error when seeking!");
+        assert_eq!(file.write(buf).unwrap(), BLOCK_SZ, "Not a complete block!");
+    }
+}
+
+fn main() {
+    easy_fs_pack().expect("Error when packing easy-fs!");
+}
+
+fn easy_fs_pack() -> std::io::Result<()> {
+    let block_file = BlockFile(Mutex::new(
+        OpenOptions::new()
+            .read(true)
+            .write(true)
+            .open("target/fs.img")?
+    ));
+    /*
+    let _efs = EasyFileSystem::create(
+        Arc::new(block_file),
+        4096,
+        1,
+    );
+     */
+    let _efs = EasyFileSystem::open(Arc::new(block_file));
+    Ok(())
+}
\ No newline at end of file
diff --git a/easy-fs/src/bitmap.rs b/easy-fs/src/bitmap.rs
new file mode 100644
index 00000000..edda5909
--- /dev/null
+++ b/easy-fs/src/bitmap.rs
@@ -0,0 +1,67 @@
+use alloc::sync::Arc;
+use super::BlockDevice;
+use super::Dirty;
+use super::BLOCK_SZ;
+
+type BitmapBlock = [u64; 64];
+
+const BLOCK_BITS: usize = BLOCK_SZ * 8;
+
+pub struct Bitmap {
+    start_block_id: usize,
+    blocks: usize,
+}
+
+/// Return (block_pos, bits64_pos, inner_pos)
+fn decomposition(mut bit: usize) -> (usize, usize, usize) {
+    let block_pos = bit / BLOCK_BITS;
+    bit = bit % BLOCK_BITS;
+    (block_pos, bit/64, bit % 64)
+}
+
+impl Bitmap {
+    pub fn new(start_block_id: usize, blocks: usize) -> Self {
+        Self {
+            start_block_id,
+            blocks,
+        }
+    }
+    pub fn alloc(&self, block_device: &Arc<dyn BlockDevice>) -> Option<usize> {
+        for block_id in 0..self.blocks {
+            let mut dirty_bitmap_block: Dirty<BitmapBlock> = Dirty::new(
+                block_id + self.start_block_id as usize,
+                0,
+                block_device.clone()
+            );
+            let bitmap_block = dirty_bitmap_block.get_mut();
+            if let Some((bits64_pos, inner_pos)) = bitmap_block
+                .iter()
+                .enumerate()
+                .find(|(_, bits64)| **bits64 != u64::MAX)
+                .map(|(bits64_pos, bits64)| {
+                    (bits64_pos, bits64.trailing_ones() as usize)
+                }) {
+                // modify cache
+                bitmap_block[bits64_pos] |= 1u64 << inner_pos;
+                return Some(block_id * BLOCK_BITS + bits64_pos * 64 + inner_pos as usize);
+                // after dirty is dropped, data will be written back automatically
+            }
+        }
+        None
+    }
+    pub fn dealloc(&self, block_device: &Arc<dyn BlockDevice>, bit: usize) {
+        let (block_pos, bits64_pos, inner_pos) = decomposition(bit);
+        let mut dirty_bitmap_block: Dirty<BitmapBlock> = Dirty::new(
+            block_pos,
+            0,
+            block_device.clone(),
+        );
+        dirty_bitmap_block.modify(|bitmap_block| {
+            assert!(bitmap_block[bits64_pos] & (1u64 << inner_pos) > 0);
+            bitmap_block[bits64_pos] -= 1u64 << inner_pos;
+        });
+    }
+    pub fn maximum(&self) -> usize {
+        self.blocks * BLOCK_BITS
+    }
+}
\ No newline at end of file
diff --git a/easy-fs/src/block_dev.rs b/easy-fs/src/block_dev.rs
new file mode 100644
index 00000000..7a282751
--- /dev/null
+++ b/easy-fs/src/block_dev.rs
@@ -0,0 +1,6 @@
+use core::any::Any;
+
+pub trait BlockDevice : Send + Sync + Any {
+    fn read_block(&self, block_id: usize, buf: &mut [u8]);
+    fn write_block(&self, block_id: usize, buf: &[u8]);
+}
diff --git a/easy-fs/src/dirty.rs b/easy-fs/src/dirty.rs
new file mode 100644
index 00000000..b1cfd33d
--- /dev/null
+++ b/easy-fs/src/dirty.rs
@@ -0,0 +1,54 @@
+use super::BlockDevice;
+use super::BLOCK_SZ;
+use alloc::sync::Arc;
+use core::marker::PhantomData;
+
+pub struct Dirty<T> {
+    block_id: usize,
+    block_cache: [u8; BLOCK_SZ],
+    offset: usize,
+    block_device: Arc<dyn BlockDevice>,
+    phantom: PhantomData<T>,
+}
+
+impl<T> Dirty<T> where T: Sized {
+    pub fn new(block_id: usize, offset: usize, block_device: Arc<dyn BlockDevice>) -> Self {
+        Self {
+            block_id,
+            block_cache: {
+                let mut cache = [0u8; BLOCK_SZ];
+                block_device.read_block(block_id as usize, &mut cache);
+                cache
+            },
+            offset,
+            block_device,
+            phantom: PhantomData,
+        }
+    }
+    pub fn get_mut(&mut self) -> &mut T {
+        let type_size = core::mem::size_of::<T>();
+        // assert that the struct is inside a block
+        assert!(self.offset + type_size <= BLOCK_SZ);
+        let start_addr = &self.block_cache[self.offset] as *const _ as usize;
+        unsafe { &mut *(start_addr as *mut T) }
+    }
+    pub fn read(&self) -> &T {
+        let type_size = core::mem::size_of::<T>();
+        // assert that the struct is inside a block
+        assert!(self.offset + type_size <= BLOCK_SZ);
+        let start_addr = &self.block_cache[self.offset] as *const _ as usize;
+        unsafe { &*(start_addr as *const T) }
+    }
+    pub fn modify(&mut self, f: impl Fn(&mut T)) {
+        f(self.get_mut());
+    }
+    pub fn write_back(&mut self) {
+        self.block_device.write_block(self.block_id as usize, &self.block_cache);
+    }
+}
+
+impl<T> Drop for Dirty<T> {
+    fn drop(&mut self) {
+        self.write_back();
+    }
+}
\ No newline at end of file
diff --git a/easy-fs/src/efs.rs b/easy-fs/src/efs.rs
new file mode 100644
index 00000000..51eef844
--- /dev/null
+++ b/easy-fs/src/efs.rs
@@ -0,0 +1,130 @@
+use alloc::sync::Arc;
+use super::{
+    BlockDevice,
+    Bitmap,
+    SuperBlock,
+    DiskInode,
+    DiskInodeType,
+    Dirty,
+};
+use crate::BLOCK_SZ;
+
+pub struct EasyFileSystem {
+    pub block_device: Arc<dyn BlockDevice>,
+    pub inode_bitmap: Bitmap,
+    pub data_bitmap: Bitmap,
+    inode_area_start_block: u32,
+    data_area_start_block: u32,
+}
+
+type DataBlock = [u8; BLOCK_SZ];
+
+impl EasyFileSystem {
+    pub fn create(
+        block_device: Arc<dyn BlockDevice>,
+        total_blocks: u32,
+        inode_bitmap_blocks: u32,
+    ) -> Self {
+        // calculate block size of areas & create bitmaps
+        let inode_bitmap = Bitmap::new(1, inode_bitmap_blocks as usize);
+        let inode_num = inode_bitmap.maximum();
+        let inode_area_blocks =
+            ((inode_num * core::mem::size_of::<DiskInode>() + BLOCK_SZ - 1) / BLOCK_SZ) as u32;
+        let inode_total_blocks = inode_bitmap_blocks + inode_area_blocks;
+        let data_total_blocks = total_blocks - 1 - inode_total_blocks;
+        let data_bitmap_blocks = (data_total_blocks + 4096) / 4097;
+        let data_area_blocks = data_total_blocks - data_bitmap_blocks;
+        let data_bitmap = Bitmap::new(
+            (1 + inode_bitmap_blocks + inode_area_blocks) as usize,
+            data_bitmap_blocks as usize,
+        );
+        let efs = Self {
+            block_device,
+            inode_bitmap,
+            data_bitmap,
+            inode_area_start_block: 1 + inode_bitmap_blocks,
+            data_area_start_block: 1 + inode_total_blocks + data_bitmap_blocks,
+        };
+        // clear all blocks
+        for i in 0..total_blocks {
+            efs.get_block(i).modify(|data_block| {
+                for byte in data_block.iter_mut() {
+                    *byte = 0;
+                }
+            });
+        }
+        // initialize SuperBlock
+        efs.get_super_block().modify(|super_block| {
+            super_block.initialize(
+                total_blocks,
+                inode_bitmap_blocks,
+                inode_area_blocks,
+                data_bitmap_blocks,
+                data_area_blocks,
+            );
+        });
+        // write back immediately
+        // create a inode for root node "/"
+        assert_eq!(efs.inode_bitmap.alloc(&efs.block_device).unwrap(), 0);
+        efs.get_disk_inode(0).modify(|disk_inode| {
+            disk_inode.initialize(DiskInodeType::Directory);
+        });
+        efs
+    }
+
+    pub fn open(block_device: Arc<dyn BlockDevice>) -> Self {
+        // read SuperBlock
+        let super_block_dirty: Dirty<SuperBlock> = Dirty::new(0, 0, block_device.clone());
+        let super_block = super_block_dirty.read();
+        assert!(super_block.is_valid(), "Error loading EFS!");
+        println!("{:?}", super_block);
+        let inode_total_blocks =
+            super_block.inode_bitmap_blocks + super_block.inode_area_blocks;
+        let efs = Self {
+            block_device,
+            inode_bitmap: Bitmap::new(
+                1,
+                super_block.inode_bitmap_blocks as usize
+            ),
+            data_bitmap: Bitmap::new(
+                (1 + inode_total_blocks) as usize,
+                super_block.data_bitmap_blocks as usize,
+            ),
+            inode_area_start_block: 1 + super_block.inode_bitmap_blocks,
+            data_area_start_block: 1 + inode_total_blocks + super_block.data_bitmap_blocks,
+        };
+        efs
+    }
+
+    fn get_super_block(&self) -> Dirty<SuperBlock> {
+        Dirty::new(0, 0, self.block_device.clone())
+    }
+
+    fn get_disk_inode(&self, inode_id: u32) -> Dirty<DiskInode> {
+        let inode_size = core::mem::size_of::<DiskInode>();
+        let inodes_per_block = (BLOCK_SZ / inode_size) as u32;
+        let block_id = self.inode_area_start_block + inode_id / inodes_per_block;
+        Dirty::new(
+            block_id as usize,
+            (inode_id % inodes_per_block) as usize * inode_size,
+            self.block_device.clone(),
+        )
+    }
+
+    fn get_data_block(&self, data_block_id: u32) -> Dirty<DataBlock> {
+        Dirty::new(
+            (self.data_area_start_block + data_block_id) as usize,
+            0,
+            self.block_device.clone(),
+        )
+    }
+
+    fn get_block(&self, block_id: u32) -> Dirty<DataBlock> {
+        Dirty::new(
+            block_id as usize,
+            0,
+            self.block_device.clone(),
+        )
+    }
+
+}
\ No newline at end of file
diff --git a/easy-fs/src/layout.rs b/easy-fs/src/layout.rs
new file mode 100644
index 00000000..75251250
--- /dev/null
+++ b/easy-fs/src/layout.rs
@@ -0,0 +1,80 @@
+use core::fmt::{Debug, Formatter, Result};
+
+const EFS_MAGIC: u32 = 0x3b800001;
+const INODE_DIRECT_COUNT: usize = 12;
+const NAME_LENGTH_LIMIT: usize = 27;
+
+#[repr(C)]
+pub struct SuperBlock {
+    magic: u32,
+    pub total_blocks: u32,
+    pub inode_bitmap_blocks: u32,
+    pub inode_area_blocks: u32,
+    pub data_bitmap_blocks: u32,
+    pub data_area_blocks: u32,
+}
+
+impl Debug for SuperBlock {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        f.debug_struct("SuperBlock")
+            .field("total_blocks", &self.total_blocks)
+            .field("inode_bitmap_blocks", &self.inode_bitmap_blocks)
+            .field("inode_area_blocks", &self.inode_area_blocks)
+            .field("data_bitmap_blocks", &self.data_bitmap_blocks)
+            .field("data_area_blocks", &self.data_area_blocks)
+            .finish()
+    }
+}
+
+impl SuperBlock {
+    pub fn initialize(
+        &mut self,
+        total_blocks: u32,
+        inode_bitmap_blocks: u32,
+        inode_area_blocks: u32,
+        data_bitmap_blocks: u32,
+        data_area_blocks: u32,
+    ) {
+        *self = Self {
+            magic: EFS_MAGIC,
+            total_blocks,
+            inode_bitmap_blocks,
+            inode_area_blocks,
+            data_bitmap_blocks,
+            data_area_blocks,
+        }
+    }
+    pub fn is_valid(&self) -> bool {
+        self.magic == EFS_MAGIC
+    }
+}
+
+pub enum DiskInodeType {
+    File,
+    Directory,
+}
+
+#[repr(C)]
+pub struct DiskInode {
+    size: u32,
+    direct: [u32; INODE_DIRECT_COUNT],
+    indirect1: u32,
+    indirect2: u32,
+    type_: DiskInodeType,
+}
+
+impl DiskInode {
+    pub fn initialize(&mut self, type_: DiskInodeType) {
+        self.size = 0;
+        self.direct.iter_mut().for_each(|v| *v = 0);
+        self.indirect1 = 0;
+        self.indirect2 = 0;
+        self.type_ = type_;
+    }
+}
+
+#[repr(C)]
+pub struct DirEntry {
+    name: [u8; NAME_LENGTH_LIMIT + 1],
+    inode_number: u32,
+}
\ No newline at end of file
diff --git a/easy-fs/src/lib.rs b/easy-fs/src/lib.rs
new file mode 100644
index 00000000..25abab63
--- /dev/null
+++ b/easy-fs/src/lib.rs
@@ -0,0 +1,15 @@
+extern crate alloc;
+
+mod block_dev;
+mod layout;
+mod efs;
+mod dirty;
+mod bitmap;
+mod vfs;
+
+pub const BLOCK_SZ: usize = 512;
+pub use block_dev::BlockDevice;
+pub use efs::EasyFileSystem;
+use layout::*;
+use dirty::Dirty;
+use bitmap::Bitmap;
\ No newline at end of file
diff --git a/easy-fs/src/vfs.rs b/easy-fs/src/vfs.rs
new file mode 100644
index 00000000..488bb7a1
--- /dev/null
+++ b/easy-fs/src/vfs.rs
@@ -0,0 +1,3 @@
+pub struct Inode {
+
+}
\ No newline at end of file