initial commit

1 files changed, 225 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
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index 0000000..414baaf
--- /dev/null
+++ b/src/main.rs
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+mod block_device;
+mod disk;
+
+use clap::Parser;
+use fuser::{Filesystem, MountOption, ReplyAttr, ReplyData, ReplyDirectory, ReplyEntry, Request};
+use std::ffi::OsStr;
+use std::sync::Arc;
+use std::time::Duration;
+use log::debug;
+
+use block_device::{memory_disk::MemoryDisk, BlockDevice, BLOCK_SIZE};
+use disk::bitmap::Bitmap;
+use disk::inode::{Inode, INODE_SIZE};
+use libc::ENOENT;
+
+#[derive(Parser, Debug)]
+#[command(author, version, about)]
+struct Args {
+    mount_point: Option<String>,
+    #[arg(long)]
+    auto_unmount: bool,
+    #[arg(long)]
+    allow_root: bool,
+}
+
+const TTL: Duration = Duration::from_secs(1);
+const INODE_PER_BLOCK: usize = BLOCK_SIZE / INODE_SIZE;
+
+/// The design of MyFS is rather simple:
+/// +-------------------+
+/// | Super Block       |
+/// +-------------------+
+/// | Inode Bitmap      |
+/// +-------------------+
+/// | ...               |
+/// +-------------------+
+/// | Data Block Bitmap |
+/// +-------------------+
+/// | ...               |
+/// +-------------------+
+/// | Inode Block       |
+/// +-------------------+
+/// | ...               |
+/// +-------------------+
+/// | Data Block        |
+/// +-------------------+
+/// With each block 4KiB, each Inode entry 128B
+
+#[repr(C)]
+struct MyFS {
+    device: Arc<dyn BlockDevice>,
+    data_bitmap: Bitmap,
+    inode_bitmap: Bitmap,
+    inode_start_block: usize,
+    data_start_block: usize,
+}
+
+impl MyFS {
+    fn new(device: Arc<dyn BlockDevice>, total_block_number: usize) -> Self {
+        let max_inode_number: usize = 16384; // TODO: remove hard-coded magic number
+        let inode_block_number = max_inode_number / INODE_PER_BLOCK; // == 128
+        let inode_bitmap_block_number = (inode_block_number + BLOCK_SIZE - 1) / BLOCK_SIZE;
+
+        let blocks_remaining =
+            total_block_number - inode_block_number - inode_bitmap_block_number - 1;
+        // let number of data blocks be x, the remaining block number be C,
+        // the corresponding data bitmap length should be ceil(x / BLK_SIZE),
+        // thus we have BLK_SIZE * (C-1) / (BLK_SIZE+1) <= x <= BLK_SIZE * C / (BLK_SIZE+1)
+        // the difference of the two bounds is less than 1,
+        // meaning only 1 integer could be in between.
+        // Thus we have x = floor(BLK_SIZE * C / (BLK_SIZE + 1))
+        let data_block_number = BLOCK_SIZE * blocks_remaining / (BLOCK_SIZE + 1);
+        let data_bitmap_block_number = blocks_remaining - data_block_number;
+        debug!("dbbn: {}", data_bitmap_block_number);
+        debug!("ibbn: {}", inode_bitmap_block_number);
+        debug!("ibn:  {}", inode_block_number);
+        debug!("dbn:  {}", data_block_number);
+        debug!("sum:  {}", 1 + data_bitmap_block_number + inode_bitmap_block_number + inode_block_number + data_block_number);
+
+        let mut data_bitmap = Bitmap::new(1, data_bitmap_block_number, device.clone());
+        let mut inode_bitmap = Bitmap::new(
+            data_bitmap_block_number + 1,
+            inode_bitmap_block_number,
+            device.clone(),
+        );
+        let mut fs = Self {
+            device,
+            data_bitmap,
+            inode_bitmap,
+            inode_start_block: data_bitmap_block_number + inode_bitmap_block_number + 1,
+            data_start_block: data_bitmap_block_number
+                + inode_bitmap_block_number
+                + inode_block_number
+                + 1,
+        };
+
+        let _ = fs.inode_bitmap.allocate(); // Inode starts from 1
+        let root_inode_index = fs.inode_bitmap.allocate();
+        assert_eq!(root_inode_index, 1);
+        let (root_inode_block, root_inode_offset) = fs.locate_inode(root_inode_index);
+        fs.put_inode(root_inode_block, root_inode_offset, Inode::directory());
+
+        fs
+    }
+
+    // pub fn allocate_inode(&mut self) -> usize {
+    //     self.inode_bitmap.allocate()
+    // }
+
+    pub fn inode_active(&self, inode: usize) -> bool {
+        self.inode_bitmap.query(inode)
+    }
+
+    /// 输入 inode 编号, 返回它对应的 block number 和 block 内 offset
+    pub fn locate_inode(&self, inode: usize) -> (usize, usize) {
+        let block_number =
+            inode / INODE_PER_BLOCK + 1 + self.inode_bitmap.length + self.data_bitmap.length;
+        let block_offset = inode % INODE_PER_BLOCK * INODE_SIZE;
+        (block_number, block_offset)
+    }
+
+    // TODO: 实现一个 LRU 的 cache 机制, 不要每次都开 buffer
+    pub fn put_inode(&mut self, block: usize, offset: usize, inode: Inode) {
+        let mut buffer = vec![0u8; BLOCK_SIZE];
+        self.device.read(block, buffer.as_mut_slice());
+
+        let inode_raw = &inode as *const Inode as *const u8;
+        let inode_slice = unsafe { std::slice::from_raw_parts(inode_raw, INODE_SIZE) };
+        buffer[offset..offset + INODE_SIZE].copy_from_slice(inode_slice);
+
+        self.device.write(block, buffer.as_slice());
+    }
+
+    // TODO: 实现一个 LRU 的 cache 机制, 不要每次都开 buffer
+    pub fn get_inode(&self, block: usize, offset: usize) -> Inode {
+        let mut buffer = vec![0u8; BLOCK_SIZE];
+        self.device.read(block, buffer.as_mut_slice());
+
+        let inode = Inode::file();
+        let inode_slice = unsafe {
+            std::slice::from_raw_parts_mut(&inode as *const Inode as *mut u8, INODE_SIZE)
+        };
+        inode_slice.copy_from_slice(&buffer[offset..offset + INODE_SIZE]);
+        inode
+    }
+}
+
+impl Filesystem for MyFS {
+    fn lookup(&mut self, _req: &Request<'_>, parent: u64, name: &OsStr, reply: ReplyEntry) {
+        debug!(
+            "Filesystem::lookup called with parent {} name {}",
+            parent,
+            name.to_str().unwrap()
+        );
+        let parent = parent as usize;
+        if self.inode_active(parent) {
+            let (block, offset) = self.locate_inode(parent);
+            let inode = self.get_inode(block, offset);
+            debug!("{:?}", inode);
+        }
+        reply.error(ENOENT);
+    }
+
+    fn getattr(&mut self, _req: &Request<'_>, ino: u64, reply: ReplyAttr) {
+        debug!("Filesystem::getattr called with ino {}", ino);
+        let ino = ino as usize;
+        if self.inode_active(ino) {
+            let (block, offset) = self.locate_inode(ino);
+            let inode = self.get_inode(block, offset);
+            debug!("{:?}", inode);
+        }
+        reply.error(ENOENT);
+    }
+
+    fn read(
+        &mut self,
+        _req: &Request<'_>,
+        ino: u64,
+        _fh: u64,
+        offset: i64,
+        _size: u32,
+        _flags: i32,
+        _lock_owner: Option<u64>,
+        reply: ReplyData,
+    ) {
+        todo!()
+    }
+
+    fn readdir(
+        &mut self,
+        _req: &Request<'_>,
+        ino: u64,
+        _fh: u64,
+        offset: i64,
+        mut reply: ReplyDirectory,
+    ) {
+        todo!()
+    }
+}
+
+fn main() {
+    env_logger::init();
+    let args = Args::parse();
+    let mount_point = args.mount_point.unwrap();
+    // let mut options = vec![
+    //     MountOption::RO,
+    //     MountOption::FSName("hello".to_string()),
+    // ];
+    // if args.allow_root {
+    //     options.push(MountOption::AutoUnmount);
+    // }
+    // if args.allow_root {
+    //     options.push(MountOption::AllowRoot);
+    // }
+    let options = vec![
+        MountOption::RO,
+        MountOption::FSName("hello".to_string()),
+        MountOption::AutoUnmount,
+        MountOption::AllowRoot,
+    ];
+    let mem_disk = Arc::new(MemoryDisk::new());
+    let filesystem = MyFS::new(mem_disk, 16384);
+
+    fuser::mount2(filesystem, mount_point, &options).unwrap();
+}