From fd125947c9db0b33761414e65e919f73d9bf1815 Mon Sep 17 00:00:00 2001
From: Chuyan Zhang <me@zcy.moe>
Date: Thu, 30 Nov 2023 12:01:11 -0800
Subject: Refactor workspace

---
 ayafs-core/src/lib.rs | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 ayafs-core/src/lib.rs

(limited to 'ayafs-core/src/lib.rs')

diff --git a/ayafs-core/src/lib.rs b/ayafs-core/src/lib.rs
new file mode 100644
index 0000000..5ec118a
--- /dev/null
+++ b/ayafs-core/src/lib.rs
@@ -0,0 +1,140 @@
+pub mod block_device;
+pub mod disk;
+pub mod filesystem;
+pub mod memory;
+pub mod tests;
+pub mod utils;
+
+
+use indexmap::IndexMap;
+use log::debug;
+use lru::LruCache;
+use std::collections::HashMap;
+use std::ffi::OsString;
+use std::num::NonZeroUsize;
+use std::sync::atomic::AtomicU64;
+use std::sync::Arc;
+use std::time::Duration;
+
+use crate::disk::block::{DirectoryEntry, InodeBlock, SuperBlock};
+use crate::memory::cached_block::BlockCache;
+use block_device::{BlockDevice, BLOCK_SIZE};
+use disk::bitmap::Bitmap;
+use disk::block::DataBlock;
+use disk::inode::INODE_SIZE;
+use users::{get_current_gid, get_current_uid};
+
+const TTL: Duration = Duration::new(0, 0);
+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)]
+pub struct AyaFS {
+    device: Arc<dyn BlockDevice>,
+    data_bitmap: Bitmap,
+    inode_bitmap: Bitmap,
+    inode_start_block: usize,
+    data_start_block: usize,
+
+    next_file_handle: AtomicU64,
+    // file descriptor -> (inode index, read, write)
+    file_handle_map: HashMap<u64, (usize, bool, bool)>,
+
+    // inode index -> (index aware) hashmap that maps dir entry name to inode index
+    dir_entry_map: LruCache<usize, IndexMap<OsString, DirectoryEntry>>,
+
+    cached_inodes: BlockCache<InodeBlock>,
+    cached_blocks: BlockCache<DataBlock>,
+
+    super_block: SuperBlock,
+}
+
+impl AyaFS {
+    pub 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!("data_bitmap_block_number: {}", data_bitmap_block_number);
+        debug!("inode_bitmap_block_number: {}", inode_bitmap_block_number);
+        debug!("inode_block_number:  {}", inode_block_number);
+        debug!("data_block_number:  {}", data_block_number);
+        debug!(
+            "sum:  {}",
+            1 + data_bitmap_block_number
+                + inode_bitmap_block_number
+                + inode_block_number
+                + data_block_number
+        );
+
+        let super_block = SuperBlock::new(
+            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 _ = data_bitmap.allocate().unwrap(); // data block 0 is not usable
+        let mut inode_bitmap = Bitmap::new(
+            data_bitmap_block_number + 1,
+            inode_bitmap_block_number,
+            device.clone(),
+        );
+        let _ = inode_bitmap.allocate().unwrap(); // inode block 0 is not usable
+
+        let mut fs = Self {
+            device: device.clone(),
+            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,
+
+            next_file_handle: AtomicU64::new(3), // 0,1,2 are stdin, stdout and stderr
+            file_handle_map: HashMap::new(),
+
+            dir_entry_map: LruCache::new(NonZeroUsize::new(1024).unwrap()),
+
+            cached_inodes: BlockCache::new(device.clone(), 1024),
+            cached_blocks: BlockCache::new(device.clone(), 8192),
+
+            super_block,
+        };
+
+        fs.create_directory(0o755, get_current_uid(), get_current_gid(), 0, None);
+
+        fs
+    }
+}
-- 
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