Substituted to the original ch7 code.

easy-fs/.gitignore

@@ -0,0 +1,3 @@
+.idea/
+target/
+Cargo.lock

easy-fs/Cargo.toml

@@ -0,0 +1,11 @@
+[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]
+spin = "0.7.0"
+lazy_static = { version = "1.4.0", features = ["spin_no_std"] }

easy-fs/src/bitmap.rs

@@ -0,0 +1,73 @@
+use alloc::sync::Arc;
+use super::{
+    BlockDevice,
+    BLOCK_SZ,
+    get_block_cache,
+};
+
+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 pos = get_block_cache(
+                block_id + self.start_block_id as usize,
+                Arc::clone(block_device),
+            ).lock().modify(0, |bitmap_block: &mut BitmapBlock| {
+                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;
+                    Some(block_id * BLOCK_BITS + bits64_pos * 64 + inner_pos as usize)
+                } else {
+                    None
+                }
+            });
+            if pos.is_some() {
+                return pos;
+            }
+        }
+        None
+    }
+
+    pub fn dealloc(&self, block_device: &Arc<dyn BlockDevice>, bit: usize) {
+        let (block_pos, bits64_pos, inner_pos) = decomposition(bit);
+        get_block_cache(
+            block_pos + self.start_block_id,
+            Arc::clone(block_device)
+        ).lock().modify(0, |bitmap_block: &mut BitmapBlock| {
+            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
+    }
+}

easy-fs/src/block_cache.rs

@@ -0,0 +1,135 @@
+use super::{
+    BLOCK_SZ,
+    BlockDevice,
+};
+use alloc::collections::VecDeque;
+use alloc::sync::Arc;
+use lazy_static::*;
+use spin::Mutex;
+
+pub struct BlockCache {
+    cache: [u8; BLOCK_SZ],
+    block_id: usize,
+    block_device: Arc<dyn BlockDevice>,
+    modified: bool,
+}
+
+impl BlockCache {
+    /// Load a new BlockCache from disk.
+    pub fn new(
+        block_id: usize,
+        block_device: Arc<dyn BlockDevice>
+    ) -> Self {
+        let mut cache = [0u8; BLOCK_SZ];
+        block_device.read_block(block_id, &mut cache);
+        Self {
+            cache,
+            block_id,
+            block_device,
+            modified: false,
+        }
+    }
+
+    fn addr_of_offset(&self, offset: usize) -> usize {
+        &self.cache[offset] as *const _ as usize
+    }
+
+    pub fn get_ref<T>(&self, offset: usize) -> &T where T: Sized {
+        let type_size = core::mem::size_of::<T>();
+        assert!(offset + type_size <= BLOCK_SZ);
+        let addr = self.addr_of_offset(offset);
+        unsafe { &*(addr as *const T) } 
+    }
+
+    pub fn get_mut<T>(&mut self, offset: usize) -> &mut T where T: Sized {
+        let type_size = core::mem::size_of::<T>();
+        assert!(offset + type_size <= BLOCK_SZ);
+        self.modified = true;
+        let addr = self.addr_of_offset(offset);
+        unsafe { &mut *(addr as *mut T) }
+    }
+
+    pub fn read<T, V>(&self, offset: usize, f: impl FnOnce(&T) -> V) -> V {
+        f(self.get_ref(offset))
+    }
+
+    pub fn modify<T, V>(&mut self, offset:usize, f: impl FnOnce(&mut T) -> V) -> V {
+        f(self.get_mut(offset))
+    }
+
+    pub fn sync(&mut self) {
+        if self.modified {
+            self.modified = false;
+            self.block_device.write_block(self.block_id, &self.cache);
+        }
+    }
+}
+
+impl Drop for BlockCache {
+    fn drop(&mut self) {
+        self.sync()
+    }
+}
+
+const BLOCK_CACHE_SIZE: usize = 16;
+
+pub struct BlockCacheManager {
+    queue: VecDeque<(usize, Arc<Mutex<BlockCache>>)>,
+}
+
+impl BlockCacheManager {
+    pub fn new() -> Self {
+        Self { queue: VecDeque::new() }
+    }
+
+    pub fn get_block_cache(
+        &mut self,
+        block_id: usize,
+        block_device: Arc<dyn BlockDevice>,
+    ) -> Arc<Mutex<BlockCache>> {
+        if let Some(pair) = self.queue
+            .iter()
+            .find(|pair| pair.0 == block_id) {
+                Arc::clone(&pair.1)
+        } else {
+            // substitute
+            if self.queue.len() == BLOCK_CACHE_SIZE {
+                // from front to tail
+                if let Some((idx, _)) = self.queue
+                    .iter()
+                    .enumerate()
+                    .find(|(_, pair)| Arc::strong_count(&pair.1) == 1) {
+                    self.queue.drain(idx..=idx);
+                } else {
+                    panic!("Run out of BlockCache!");
+                }
+            }
+            // load block into mem and push back
+            let block_cache = Arc::new(Mutex::new(
+                BlockCache::new(block_id, Arc::clone(&block_device))
+            ));
+            self.queue.push_back((block_id, Arc::clone(&block_cache)));
+            block_cache
+        }
+    }
+}
+
+lazy_static! {
+    pub static ref BLOCK_CACHE_MANAGER: Mutex<BlockCacheManager> = Mutex::new(
+        BlockCacheManager::new()
+    );
+}
+
+pub fn get_block_cache(
+    block_id: usize,
+    block_device: Arc<dyn BlockDevice>
+) -> Arc<Mutex<BlockCache>> {
+    BLOCK_CACHE_MANAGER.lock().get_block_cache(block_id, block_device)
+}
+
+pub fn block_cache_sync_all() {
+    let manager = BLOCK_CACHE_MANAGER.lock();
+    for (_, cache) in manager.queue.iter() {
+        cache.lock().sync();
+    }
+}

easy-fs/src/block_dev.rs

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+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]);
+}

easy-fs/src/efs.rs

@@ -0,0 +1,163 @@
+use alloc::sync::Arc;
+use spin::Mutex;
+use super::{
+    BlockDevice,
+    Bitmap,
+    SuperBlock,
+    DiskInode,
+    DiskInodeType,
+    Inode,
+    get_block_cache,
+    block_cache_sync_all,
+};
+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,
+    ) -> Arc<Mutex<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 mut efs = Self {
+            block_device: Arc::clone(&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 {
+            get_block_cache(
+                i as usize,
+                Arc::clone(&block_device)
+            )
+            .lock()
+            .modify(0, |data_block: &mut DataBlock| {
+                for byte in data_block.iter_mut() { *byte = 0; }
+            });
+        }
+        // initialize SuperBlock
+        get_block_cache(0, Arc::clone(&block_device))
+        .lock()
+        .modify(0, |super_block: &mut SuperBlock| {
+            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.alloc_inode(), 0);
+        let (root_inode_block_id, root_inode_offset) = efs.get_disk_inode_pos(0);
+        get_block_cache(
+            root_inode_block_id as usize,
+            Arc::clone(&block_device)
+        )
+        .lock()
+        .modify(root_inode_offset, |disk_inode: &mut DiskInode| {
+            disk_inode.initialize(DiskInodeType::Directory);
+        });
+        block_cache_sync_all();
+        Arc::new(Mutex::new(efs))
+    }
+
+    pub fn open(block_device: Arc<dyn BlockDevice>) -> Arc<Mutex<Self>> {
+        // read SuperBlock
+        get_block_cache(0, Arc::clone(&block_device))
+            .lock()
+            .read(0, |super_block: &SuperBlock| {
+                assert!(super_block.is_valid(), "Error loading EFS!");
+                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,
+                };
+                Arc::new(Mutex::new(efs))
+            })
+    }
+
+    pub fn root_inode(efs: &Arc<Mutex<Self>>) -> Inode {
+        let block_device = Arc::clone(&efs.lock().block_device);
+        // acquire efs lock temporarily
+        let (block_id, block_offset) = efs.lock().get_disk_inode_pos(0);
+        // release efs lock
+        Inode::new(
+            block_id,
+            block_offset,
+            Arc::clone(efs),
+            block_device,
+        )
+    }
+
+    pub fn get_disk_inode_pos(&self, inode_id: u32) -> (u32, usize) {
+        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;
+        (block_id, (inode_id % inodes_per_block) as usize * inode_size)
+    }
+
+    pub fn get_data_block_id(&self, data_block_id: u32) -> u32 {
+        self.data_area_start_block + data_block_id
+    }
+
+    pub fn alloc_inode(&mut self) -> u32 {
+        self.inode_bitmap.alloc(&self.block_device).unwrap() as u32
+    }
+
+    /// Return a block ID not ID in the data area.
+    pub fn alloc_data(&mut self) -> u32 {
+        self.data_bitmap.alloc(&self.block_device).unwrap() as u32 + self.data_area_start_block
+    }
+
+    pub fn dealloc_data(&mut self, block_id: u32) {
+        get_block_cache(
+            block_id as usize,
+            Arc::clone(&self.block_device)
+        )
+        .lock()
+        .modify(0, |data_block: &mut DataBlock| {
+            data_block.iter_mut().for_each(|p| { *p = 0; })
+        });
+        self.data_bitmap.dealloc(
+            &self.block_device,
+            (block_id - self.data_area_start_block) as usize
+        )
+    }
+
+}

easy-fs/src/layout.rs

@@ -0,0 +1,448 @@
+use core::fmt::{Debug, Formatter, Result};
+use super::{
+    BLOCK_SZ,
+    BlockDevice,
+    get_block_cache,
+};
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+
+const EFS_MAGIC: u32 = 0x3b800001;
+const INODE_DIRECT_COUNT: usize = 28;
+const NAME_LENGTH_LIMIT: usize = 27;
+const INODE_INDIRECT1_COUNT: usize = BLOCK_SZ / 4;
+const INODE_INDIRECT2_COUNT: usize = INODE_INDIRECT1_COUNT * INODE_INDIRECT1_COUNT;
+const DIRECT_BOUND: usize = INODE_DIRECT_COUNT;
+const INDIRECT1_BOUND: usize = DIRECT_BOUND + INODE_INDIRECT1_COUNT;
+#[allow(unused)]
+const INDIRECT2_BOUND: usize = INDIRECT1_BOUND + INODE_INDIRECT2_COUNT;
+
+#[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
+    }
+}
+
+#[derive(PartialEq)]
+pub enum DiskInodeType {
+    File,
+    Directory,
+}
+
+type IndirectBlock = [u32; BLOCK_SZ / 4];
+type DataBlock = [u8; BLOCK_SZ];
+
+#[repr(C)]
+pub struct DiskInode {
+    pub size: u32,
+    pub direct: [u32; INODE_DIRECT_COUNT],
+    pub indirect1: u32,
+    pub indirect2: u32,
+    type_: DiskInodeType,
+}
+
+impl DiskInode {
+    /// indirect1 and indirect2 block are allocated only when they are needed.
+    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_;
+    }
+    pub fn is_dir(&self) -> bool {
+        self.type_ == DiskInodeType::Directory
+    }
+    #[allow(unused)]
+    pub fn is_file(&self) -> bool {
+        self.type_ == DiskInodeType::File
+    }
+    /// Return block number correspond to size.
+    pub fn data_blocks(&self) -> u32 {
+        Self::_data_blocks(self.size)
+    }
+    fn _data_blocks(size: u32) -> u32 {
+        (size + BLOCK_SZ as u32 - 1) / BLOCK_SZ as u32
+    }
+    /// Return number of blocks needed include indirect1/2.
+    pub fn total_blocks(size: u32) -> u32 {
+        let data_blocks = Self::_data_blocks(size) as usize;
+        let mut total = data_blocks as usize;
+        // indirect1
+        if data_blocks > INODE_DIRECT_COUNT {
+            total += 1;
+        }
+        // indirect2
+        if data_blocks > INDIRECT1_BOUND {
+            total += 1;
+            // sub indirect1
+            total += (data_blocks - INDIRECT1_BOUND + INODE_INDIRECT1_COUNT - 1) / INODE_INDIRECT1_COUNT;
+        }
+        total as u32
+    }
+    pub fn blocks_num_needed(&self, new_size: u32) -> u32 {
+        assert!(new_size >= self.size);
+        Self::total_blocks(new_size) - Self::total_blocks(self.size)
+    }
+    pub fn get_block_id(&self, inner_id: u32, block_device: &Arc<dyn BlockDevice>) -> u32 {
+        let inner_id = inner_id as usize;
+        if inner_id < INODE_DIRECT_COUNT {
+            self.direct[inner_id]
+        } else if inner_id < INDIRECT1_BOUND {
+            get_block_cache(self.indirect1 as usize, Arc::clone(block_device))
+                .lock()
+                .read(0, |indirect_block: &IndirectBlock| {
+                    indirect_block[inner_id - INODE_DIRECT_COUNT]
+                })
+        } else {
+            let last = inner_id - INDIRECT1_BOUND;
+            let indirect1 = get_block_cache(
+                self.indirect2 as usize,
+                Arc::clone(block_device)
+            )
+            .lock()
+            .read(0, |indirect2: &IndirectBlock| {
+                indirect2[last / INODE_INDIRECT1_COUNT]
+            });
+            get_block_cache(
+                indirect1 as usize,
+                Arc::clone(block_device)
+            )
+            .lock()
+            .read(0, |indirect1: &IndirectBlock| {
+                indirect1[last % INODE_INDIRECT1_COUNT]
+            })
+        }
+    }
+    pub fn increase_size(
+        &mut self,
+        new_size: u32,
+        new_blocks: Vec<u32>,
+        block_device: &Arc<dyn BlockDevice>,
+    ) {
+        let mut current_blocks = self.data_blocks();
+        self.size = new_size;
+        let mut total_blocks = self.data_blocks();
+        let mut new_blocks = new_blocks.into_iter();
+        // fill direct
+        while current_blocks < total_blocks.min(INODE_DIRECT_COUNT as u32) {
+            self.direct[current_blocks as usize] = new_blocks.next().unwrap();
+            current_blocks += 1;
+        }
+        // alloc indirect1
+        if total_blocks > INODE_DIRECT_COUNT as u32{
+            if current_blocks == INODE_DIRECT_COUNT as u32 {
+                self.indirect1 = new_blocks.next().unwrap();
+            }
+            current_blocks -= INODE_DIRECT_COUNT as u32;
+            total_blocks -= INODE_DIRECT_COUNT as u32;
+        } else {
+            return;
+        }
+        // fill indirect1
+        get_block_cache(
+            self.indirect1 as usize,
+            Arc::clone(block_device)
+        )
+        .lock()
+        .modify(0, |indirect1: &mut IndirectBlock| {
+            while current_blocks < total_blocks.min(INODE_INDIRECT1_COUNT as u32) {
+                indirect1[current_blocks as usize] = new_blocks.next().unwrap();
+                current_blocks += 1;
+            }
+        });
+        // alloc indirect2
+        if total_blocks > INODE_INDIRECT1_COUNT as u32 {
+            if current_blocks == INODE_INDIRECT1_COUNT as u32 {
+                self.indirect2 = new_blocks.next().unwrap();
+            }
+            current_blocks -= INODE_INDIRECT1_COUNT as u32;
+            total_blocks -= INODE_INDIRECT1_COUNT as u32;
+        } else {
+            return;
+        }
+        // fill indirect2 from (a0, b0) -> (a1, b1)
+        let mut a0 = current_blocks as usize / INODE_INDIRECT1_COUNT;
+        let mut b0 = current_blocks as usize % INODE_INDIRECT1_COUNT;
+        let a1 = total_blocks as usize / INODE_INDIRECT1_COUNT;
+        let b1 = total_blocks as usize % INODE_INDIRECT1_COUNT;
+        // alloc low-level indirect1
+        get_block_cache(
+            self.indirect2 as usize,
+            Arc::clone(block_device)
+        )
+        .lock()
+        .modify(0, |indirect2: &mut IndirectBlock| {
+            while (a0 < a1) || (a0 == a1 && b0 < b1) {
+                if b0 == 0 {
+                    indirect2[a0] = new_blocks.next().unwrap();
+                }
+                // fill current
+                get_block_cache(
+                    indirect2[a0] as usize,
+                    Arc::clone(block_device)
+                )
+                .lock()
+                .modify(0, |indirect1: &mut IndirectBlock| {
+                    indirect1[b0] = new_blocks.next().unwrap();
+                });
+                // move to next
+                b0 += 1;
+                if b0 == INODE_INDIRECT1_COUNT {
+                    b0 = 0;
+                    a0 += 1;
+                }
+            }
+        });
+    }
+
+    /// Clear size to zero and return blocks that should be deallocated.
+    ///
+    /// We will clear the block contents to zero later.
+    pub fn clear_size(&mut self, block_device: &Arc<dyn BlockDevice>) -> Vec<u32> {
+        let mut v: Vec<u32> = Vec::new();
+        let mut data_blocks = self.data_blocks() as usize;
+        self.size = 0;
+        let mut current_blocks = 0usize;
+        // direct
+        while current_blocks < data_blocks.min(INODE_DIRECT_COUNT) {
+            v.push(self.direct[current_blocks]);
+            self.direct[current_blocks] = 0;
+            current_blocks += 1;
+        }
+        // indirect1 block
+        if data_blocks > INODE_DIRECT_COUNT {
+            v.push(self.indirect1);
+            data_blocks -= INODE_DIRECT_COUNT;
+            current_blocks = 0;
+        } else {
+            return v;
+        }
+        // indirect1
+        get_block_cache(
+            self.indirect1 as usize,
+            Arc::clone(block_device),
+        )
+        .lock()
+        .modify(0, |indirect1: &mut IndirectBlock| {
+            while current_blocks < data_blocks.min(INODE_INDIRECT1_COUNT) {
+                v.push(indirect1[current_blocks]);
+                //indirect1[current_blocks] = 0;
+                current_blocks += 1;
+            }
+        });
+        self.indirect1 = 0;
+        // indirect2 block
+        if data_blocks > INODE_INDIRECT1_COUNT {
+            v.push(self.indirect2);
+            data_blocks -= INODE_INDIRECT1_COUNT;
+        } else {
+            return v;
+        }
+        // indirect2
+        assert!(data_blocks <= INODE_INDIRECT2_COUNT);
+        let a1 = data_blocks / INODE_INDIRECT1_COUNT;
+        let b1 = data_blocks % INODE_INDIRECT1_COUNT;
+        get_block_cache(
+            self.indirect2 as usize,
+            Arc::clone(block_device),
+        )
+        .lock()
+        .modify(0, |indirect2: &mut IndirectBlock| {
+            // full indirect1 blocks
+            for i in 0..a1 {
+                v.push(indirect2[i]);
+                get_block_cache(
+                    indirect2[i] as usize,
+                    Arc::clone(block_device),
+                )
+                .lock()
+                .modify(0, |indirect1: &mut IndirectBlock| {
+                    for j in 0..INODE_INDIRECT1_COUNT {
+                        v.push(indirect1[j]);
+                        //indirect1[j] = 0;
+                    }
+                });
+                //indirect2[i] = 0;
+            }
+            // last indirect1 block
+            if b1 > 0 {
+                v.push(indirect2[a1]);
+                get_block_cache(
+                    indirect2[a1] as usize,
+                    Arc::clone(block_device),
+                )
+                .lock()
+                .modify(0, |indirect1: &mut IndirectBlock| {
+                    for j in 0..b1 {
+                        v.push(indirect1[j]);
+                        //indirect1[j] = 0;
+                    }
+                });
+                //indirect2[a1] = 0;
+            }
+        });
+        self.indirect2 = 0;
+        v
+    }
+    pub fn read_at(
+        &self,
+        offset: usize,
+        buf: &mut [u8],
+        block_device: &Arc<dyn BlockDevice>,
+    ) -> usize {
+        let mut start = offset;
+        let end = (offset + buf.len()).min(self.size as usize);
+        if start >= end {
+            return 0;
+        }
+        let mut start_block = start / BLOCK_SZ;
+        let mut read_size = 0usize;
+        loop {
+            // calculate end of current block
+            let mut end_current_block = (start / BLOCK_SZ + 1) * BLOCK_SZ;
+            end_current_block = end_current_block.min(end);
+            // read and update read size
+            let block_read_size = end_current_block - start;
+            let dst = &mut buf[read_size..read_size + block_read_size];
+            get_block_cache(
+                self.get_block_id(start_block as u32, block_device) as usize,
+                Arc::clone(block_device),
+            )
+            .lock()
+            .read(0, |data_block: &DataBlock| {
+                let src = &data_block[start % BLOCK_SZ..start % BLOCK_SZ + block_read_size];
+                dst.copy_from_slice(src);
+            });
+            read_size += block_read_size;
+            // move to next block
+            if end_current_block == end { break; }
+            start_block += 1;
+            start = end_current_block;
+        }
+        read_size
+    }
+    /// File size must be adjusted before.
+    pub fn write_at(
+        &mut self,
+        offset: usize,
+        buf: &[u8],
+        block_device: &Arc<dyn BlockDevice>,
+    ) -> usize {
+        let mut start = offset;
+        let end = (offset + buf.len()).min(self.size as usize);
+        assert!(start <= end);
+        let mut start_block = start / BLOCK_SZ;
+        let mut write_size = 0usize;
+        loop {
+            // calculate end of current block
+            let mut end_current_block = (start / BLOCK_SZ + 1) * BLOCK_SZ;
+            end_current_block = end_current_block.min(end);
+            // write and update write size
+            let block_write_size = end_current_block - start;
+            get_block_cache(
+                self.get_block_id(start_block as u32, block_device) as usize,
+                Arc::clone(block_device)
+            )
+            .lock()
+            .modify(0, |data_block: &mut DataBlock| {
+                let src = &buf[write_size..write_size + block_write_size];
+                let dst = &mut data_block[start % BLOCK_SZ..start % BLOCK_SZ + block_write_size];
+                dst.copy_from_slice(src);
+            });
+            write_size += block_write_size;
+            // move to next block
+            if end_current_block == end { break; }
+            start_block += 1;
+            start = end_current_block;
+        }
+        write_size
+    }
+}
+
+#[repr(C)]
+pub struct DirEntry {
+    name: [u8; NAME_LENGTH_LIMIT + 1],
+    inode_number: u32,
+}
+
+pub const DIRENT_SZ: usize = 32;
+
+impl DirEntry {
+    pub fn empty() -> Self {
+        Self {
+            name: [0u8; NAME_LENGTH_LIMIT + 1],
+            inode_number: 0,
+        }
+    }
+    pub fn new(name: &str, inode_number: u32) -> Self {
+        let mut bytes = [0u8; NAME_LENGTH_LIMIT + 1];
+        bytes[..name.len()].copy_from_slice(name.as_bytes());
+        Self {
+            name: bytes,
+            inode_number,
+        }
+    }
+    pub fn as_bytes(&self) -> &[u8] {
+        unsafe {
+            core::slice::from_raw_parts(
+                self as *const _ as usize as *const u8,
+                DIRENT_SZ,
+            )
+        }
+    }
+    pub fn as_bytes_mut(&mut self) -> &mut [u8] {
+        unsafe {
+            core::slice::from_raw_parts_mut(
+                self as *mut _ as usize as *mut u8,
+                DIRENT_SZ,
+            )
+        }
+    }
+    pub fn name(&self) -> &str {
+        let len = (0usize..).find(|i| self.name[*i] == 0).unwrap();
+        core::str::from_utf8(&self.name[..len]).unwrap()
+    }
+    pub fn inode_number(&self) -> u32 {
+        self.inode_number
+    }
+}

easy-fs/src/lib.rs

@@ -0,0 +1,18 @@
+#![no_std]
+
+extern crate alloc;
+
+mod block_dev;
+mod layout;
+mod efs;
+mod bitmap;
+mod vfs;
+mod block_cache;
+
+pub const BLOCK_SZ: usize = 512;
+pub use block_dev::BlockDevice;
+pub use efs::EasyFileSystem;
+pub use vfs::Inode;
+use layout::*;
+use bitmap::Bitmap;
+use block_cache::{get_block_cache, block_cache_sync_all};

easy-fs/src/vfs.rs

@@ -0,0 +1,210 @@
+use super::{
+    BlockDevice,
+    DiskInode,
+    DiskInodeType,
+    DirEntry,
+    EasyFileSystem,
+    DIRENT_SZ,
+    get_block_cache,
+    block_cache_sync_all,
+};
+use alloc::sync::Arc;
+use alloc::string::String;
+use alloc::vec::Vec;
+use spin::{Mutex, MutexGuard};
+
+pub struct Inode {
+    block_id: usize,
+    block_offset: usize,
+    fs: Arc<Mutex<EasyFileSystem>>,
+    block_device: Arc<dyn BlockDevice>,
+}
+
+impl Inode {
+    /// We should not acquire efs lock here.
+    pub fn new(
+        block_id: u32,
+        block_offset: usize,
+        fs: Arc<Mutex<EasyFileSystem>>,
+        block_device: Arc<dyn BlockDevice>,
+    ) -> Self {
+        Self {
+            block_id: block_id as usize,
+            block_offset,
+            fs,
+            block_device,
+        }
+    }
+
+    fn read_disk_inode<V>(&self, f: impl FnOnce(&DiskInode) -> V) -> V {
+        get_block_cache(
+            self.block_id,
+            Arc::clone(&self.block_device)
+        ).lock().read(self.block_offset, f)
+    }
+
+    fn modify_disk_inode<V>(&self, f: impl FnOnce(&mut DiskInode) -> V) -> V {
+        get_block_cache(
+            self.block_id,
+            Arc::clone(&self.block_device)
+        ).lock().modify(self.block_offset, f)
+    }
+
+    fn find_inode_id(
+        &self,
+        name: &str,
+        disk_inode: &DiskInode,
+    ) -> Option<u32> {
+        // assert it is a directory
+        assert!(disk_inode.is_dir());
+        let file_count = (disk_inode.size as usize) / DIRENT_SZ;
+        let mut dirent = DirEntry::empty();
+        for i in 0..file_count {
+            assert_eq!(
+                disk_inode.read_at(
+                    DIRENT_SZ * i,
+                    dirent.as_bytes_mut(),
+                    &self.block_device,
+                ),
+                DIRENT_SZ,
+            );
+            if dirent.name() == name {
+                return Some(dirent.inode_number() as u32);
+            }
+        }
+        None
+    }
+
+    pub fn find(&self, name: &str) -> Option<Arc<Inode>> {
+        let fs = self.fs.lock();
+        self.read_disk_inode(|disk_inode| {
+            self.find_inode_id(name, disk_inode)
+            .map(|inode_id| {
+                let (block_id, block_offset) = fs.get_disk_inode_pos(inode_id);
+                Arc::new(Self::new(
+                    block_id,
+                    block_offset,
+                    self.fs.clone(),
+                    self.block_device.clone(),
+                ))
+            })
+        })
+    }
+
+    fn increase_size(
+        &self,
+        new_size: u32,
+        disk_inode: &mut DiskInode,
+        fs: &mut MutexGuard<EasyFileSystem>,
+    ) {
+        if new_size < disk_inode.size {
+            return;
+        }
+        let blocks_needed = disk_inode.blocks_num_needed(new_size);
+        let mut v: Vec<u32> = Vec::new();
+        for _ in 0..blocks_needed {
+            v.push(fs.alloc_data());
+        }
+        disk_inode.increase_size(new_size, v, &self.block_device);
+    }
+
+    pub fn create(&self, name: &str) -> Option<Arc<Inode>> {
+        let mut fs = self.fs.lock();
+        if self.modify_disk_inode(|root_inode| {
+            // assert it is a directory
+            assert!(root_inode.is_dir());
+            // has the file been created?
+            self.find_inode_id(name, root_inode)
+        }).is_some() {
+            return None;
+        }
+        // create a new file
+        // alloc a inode with an indirect block
+        let new_inode_id = fs.alloc_inode();
+        // initialize inode
+        let (new_inode_block_id, new_inode_block_offset) 
+            = fs.get_disk_inode_pos(new_inode_id);
+        get_block_cache(
+            new_inode_block_id as usize,
+            Arc::clone(&self.block_device)
+        ).lock().modify(new_inode_block_offset, |new_inode: &mut DiskInode| {
+            new_inode.initialize(DiskInodeType::File);
+        });
+        self.modify_disk_inode(|root_inode| {
+            // append file in the dirent
+            let file_count = (root_inode.size as usize) / DIRENT_SZ;
+            let new_size = (file_count + 1) * DIRENT_SZ;
+            // increase size
+            self.increase_size(new_size as u32, root_inode, &mut fs);
+            // write dirent
+            let dirent = DirEntry::new(name, new_inode_id);
+            root_inode.write_at(
+                file_count * DIRENT_SZ,
+                dirent.as_bytes(),
+                &self.block_device,
+            );
+        });
+
+        let (block_id, block_offset) = fs.get_disk_inode_pos(new_inode_id);
+        block_cache_sync_all();
+        // return inode
+        Some(Arc::new(Self::new(
+            block_id,
+            block_offset,
+            self.fs.clone(),
+            self.block_device.clone(),
+        )))
+        // release efs lock automatically by compiler
+    }
+
+    pub fn ls(&self) -> Vec<String> {
+        let _fs = self.fs.lock();
+        self.read_disk_inode(|disk_inode| {
+            let file_count = (disk_inode.size as usize) / DIRENT_SZ;
+            let mut v: Vec<String> = Vec::new();
+            for i in 0..file_count {
+                let mut dirent = DirEntry::empty();
+                assert_eq!(
+                    disk_inode.read_at(
+                        i * DIRENT_SZ,
+                        dirent.as_bytes_mut(),
+                        &self.block_device,
+                    ),
+                    DIRENT_SZ,
+                );
+                v.push(String::from(dirent.name()));
+            }
+            v
+        })
+    }
+
+    pub fn read_at(&self, offset: usize, buf: &mut [u8]) -> usize {
+        let _fs = self.fs.lock();
+        self.read_disk_inode(|disk_inode| {
+            disk_inode.read_at(offset, buf, &self.block_device)
+        })
+    }
+
+    pub fn write_at(&self, offset: usize, buf: &[u8]) -> usize {
+        let mut fs = self.fs.lock();
+        let size = self.modify_disk_inode(|disk_inode| {
+            self.increase_size((offset + buf.len()) as u32, disk_inode, &mut fs);
+            disk_inode.write_at(offset, buf, &self.block_device)
+        });
+        block_cache_sync_all();
+        size
+    }
+
+    pub fn clear(&self) {
+        let mut fs = self.fs.lock();
+        self.modify_disk_inode(|disk_inode| {
+            let size = disk_inode.size;
+            let data_blocks_dealloc = disk_inode.clear_size(&self.block_device);
+            assert!(data_blocks_dealloc.len() == DiskInode::total_blocks(size) as usize);
+            for data_block in data_blocks_dealloc.into_iter() {
+                fs.dealloc_data(data_block);
+            }
+        });
+        block_cache_sync_all();
+    }
+}