Refactor workspace

5 files changed, 1179 insertions, 0 deletions

diff --git a/ayafs-core/src/disk/allocation.rs b/ayafs-core/src/disk/allocation.rs
new file mode 100644
index 0000000..a187fad
--- /dev/null
+++ b/ayafs-core/src/disk/allocation.rs
@@ -0,0 +1,542 @@
+use crate::disk::block::{
+    Block, DataBlock, DoubleIndirectBlock, IndirectBlock, TripleIndirectBlock,
+};
+use crate::disk::inode::{Inode, DIRECT_NUMBER, ENTRY_PER_BLOCK};
+use crate::memory::cached_block::{convert, CachedBlock};
+use crate::AyaFS;
+use libc::c_int;
+use log::debug;
+
+impl AyaFS {
+    /// 为 Inode 分配新 block, 返回 block 的编号和它在 inode 内的编号
+    pub(crate) fn allocate_block_for(&mut self, inode: &mut Inode) -> Option<(u32, usize)> {
+        // 先看这个 inode 的 direct block 有没有空闲
+        for (index_within_direct, index) in inode.direct.iter_mut().enumerate() {
+            if !self.data_bitmap.query(*index as usize) {
+                let block_index = self.data_bitmap.allocate().unwrap() as u32;
+                // println!("allocating {} for direct", block_index);
+                *index = block_index;
+                inode.n_blocks += 1;
+                // 初始化这个 block
+                self.init_block(block_index as usize);
+                // 当调用 get_inode_mut 拿出 &mut Inode 的时候对应的 block 在 cache 里已经脏了
+                return Some((block_index, index_within_direct));
+            }
+        }
+
+        // direct block 全部分配完了, 先检查 indirect block 有没有分配, 没有就分配一个
+        if !self.data_bitmap.query(inode.single_indirect as usize) {
+            inode.single_indirect = self
+                .data_bitmap
+                .allocate()
+                .expect("No free space for new block") as u32;
+            self.init_block(inode.single_indirect as usize);
+            // println!("allocating {} for indirect", inode.single_indirect);
+        }
+        // 在 indirect block 里尝试分配
+        if let Some((block_index, index_within_indirect)) =
+            self.allocate_in_indirect(inode.single_indirect)
+        {
+            // println!("allocating {} in indirect", block_index);
+            inode.n_blocks += 1;
+
+            let index_within_block = DIRECT_NUMBER + index_within_indirect;
+            return Some((block_index, index_within_block));
+        }
+
+        // direct & indirect block 全部分配完了, 先检查 double indirect block 有没有分配, 没有就分配一个
+        if !self.data_bitmap.query(inode.double_indirect as usize) {
+            inode.double_indirect = self
+                .data_bitmap
+                .allocate()
+                .expect("No free space for new block") as u32;
+            self.init_block(inode.double_indirect as usize);
+            // println!("allocating {} for double indirect", inode.double_indirect);
+        }
+        // 在 double indirect block 里尝试分配
+        if let Some((block_index, index_within_double)) =
+            self.alloc_in_double_indirect(inode.double_indirect)
+        {
+            // println!("allocating {} in double indirect", block_index);
+            inode.n_blocks += 1;
+            let index_within_block = DIRECT_NUMBER + ENTRY_PER_BLOCK + index_within_double;
+            return Some((block_index, index_within_block));
+        }
+
+        // direct, indirect & double indirect block 全部分配完了, 先检查 triple indirect block 有没有分配, 没有就分配一个
+        if !self.data_bitmap.query(inode.triple_indirect as usize) {
+            inode.triple_indirect = self
+                .data_bitmap
+                .allocate()
+                .expect("No free space for new block") as u32;
+            self.init_block(inode.triple_indirect as usize);
+            // println!("allocating {} for triple indirect", inode.triple_indirect);
+        }
+        // 在 double indirect block 里尝试分配
+        if let Some((block_index, index_within_triple)) =
+            self.alloc_in_triple_indirect(inode.triple_indirect)
+        {
+            // println!("allocating {} in triple indirect", block_index);
+            inode.n_blocks += 1;
+            let index_within_block = DIRECT_NUMBER
+                + ENTRY_PER_BLOCK
+                + ENTRY_PER_BLOCK * ENTRY_PER_BLOCK
+                + index_within_triple;
+            return Some((block_index, index_within_block));
+        }
+        None
+    }
+
+    fn allocate_in_indirect(&mut self, indirect_entry: u32) -> Option<(u32, usize)> {
+        // 取出 single indirect block, 尝试在里面分配
+        let indirect_entry = indirect_entry as usize;
+        // println!("finding indirect block with number {}, bitmap says {}", indirect_entry, self.data_bitmap.query(indirect_entry));
+
+        if let Some(block) = self
+            .get_block(indirect_entry)
+            .map(convert::<DataBlock, IndirectBlock>)
+        {
+            // println!("found indirect block with number {}", indirect_entry);
+            let mut indirect_block = block.clone();
+            for (index_within_indirect, entry) in
+                indirect_block.block.entries.iter_mut().enumerate()
+            {
+                if self.data_bitmap.query(*entry as usize) == false {
+                    indirect_block.dirty = true; // 把这个块标记为 dirty
+                    let block_index = self.data_bitmap.allocate().expect("No free space") as u32;
+                    self.init_block(block_index as usize);
+                    *entry = block_index;
+                    self.update_block(indirect_block);
+                    return Some((block_index, index_within_indirect));
+                }
+            }
+        }
+        None
+    }
+
+    fn alloc_in_double_indirect(&mut self, double_indirect_entry: u32) -> Option<(u32, usize)> {
+        let double_indirect_entry = double_indirect_entry as usize;
+
+        if let Some(block) = self
+            .get_block(double_indirect_entry)
+            .map(convert::<DataBlock, DoubleIndirectBlock>)
+        {
+            let mut double_indirect_block = block.clone();
+            let mut double_indirect_modified = false;
+            for (index_within_double_indirect, indirect_entry) in
+                double_indirect_block.block.indirect.iter_mut().enumerate()
+            {
+                if self.data_bitmap.query(*indirect_entry as usize) == false {
+                    double_indirect_block.dirty = true;
+                    double_indirect_modified = true;
+
+                    let indirect_index = self.data_bitmap.allocate().expect("No free space");
+                    *indirect_entry = indirect_index as u32;
+                    self.init_block(indirect_index);
+                }
+
+                if let Some((block_index, index_within_indirect)) =
+                    self.allocate_in_indirect(*indirect_entry)
+                {
+                    if double_indirect_modified {
+                        self.update_block(double_indirect_block);
+                    }
+                    let index_within_double =
+                        index_within_double_indirect * ENTRY_PER_BLOCK + index_within_indirect;
+                    return Some((block_index, index_within_double));
+                }
+            }
+        }
+        None
+    }
+
+    fn alloc_in_triple_indirect(&mut self, triple_indirect_entry: u32) -> Option<(u32, usize)> {
+        let triple_indirect_entry = triple_indirect_entry as usize;
+
+        if let Some(block) = self
+            .get_block(triple_indirect_entry)
+            .map(convert::<DataBlock, TripleIndirectBlock>)
+        {
+            let mut triple_indirect_block = block.clone();
+            let mut triple_indirect_modified = false;
+            for (index_within_triple_indirect, double_indirect_entry) in triple_indirect_block
+                .block
+                .double_indirect
+                .iter_mut()
+                .enumerate()
+            {
+                if self.data_bitmap.query(*double_indirect_entry as usize) == false {
+                    triple_indirect_block.dirty = true;
+                    triple_indirect_modified = true;
+
+                    let double_indirect_index = self.data_bitmap.allocate().expect("No free space");
+                    *double_indirect_entry = double_indirect_index as u32;
+                    self.init_block(double_indirect_index)
+                }
+                if let Some((block_index, index_within_double_indirect)) =
+                    self.alloc_in_double_indirect(*double_indirect_entry)
+                {
+                    if triple_indirect_modified {
+                        self.update_block(triple_indirect_block);
+                    }
+                    let index_within_triple =
+                        index_within_triple_indirect * ENTRY_PER_BLOCK * ENTRY_PER_BLOCK
+                            + index_within_double_indirect;
+                    return Some((block_index, index_within_triple));
+                }
+            }
+        }
+        None
+    }
+}
+
+impl AyaFS {
+    pub(crate) fn deallocate_all_blocks_for(&mut self, inode: &Inode) -> Result<(), c_int> {
+        // 遍历 direct block 并删除
+        for block_index in inode.direct {
+            self.data_bitmap.deallocate(block_index as usize);
+        }
+
+        // 遍历 indirect block 并删除
+        if self.data_bitmap.query(inode.single_indirect as usize) {
+            let indirect = self
+                .get_block::<IndirectBlock>(inode.single_indirect as usize)
+                .unwrap();
+            for block_index in indirect.block.entries {
+                self.data_bitmap.deallocate(block_index as usize);
+            }
+            self.data_bitmap.deallocate(inode.single_indirect as usize);
+        }
+
+        // 遍历 double indirect block 并删除
+        if self.data_bitmap.query(inode.double_indirect as usize) {
+            let double_indirect = self
+                .get_block::<DoubleIndirectBlock>(inode.double_indirect as usize)
+                .unwrap();
+            for indirect_block_index in double_indirect.block.indirect {
+                if let Some(indirect) =
+                    self.get_block::<IndirectBlock>(indirect_block_index as usize)
+                {
+                    for block_index in indirect.block.entries {
+                        self.data_bitmap.deallocate(block_index as usize);
+                    }
+                    self.data_bitmap.deallocate(indirect_block_index as usize);
+                }
+            }
+            self.data_bitmap.deallocate(inode.double_indirect as usize);
+        }
+
+        // 遍历 triple indirect block 并删除
+        if self.data_bitmap.query(inode.triple_indirect as usize) {
+            let triple_indirect = self
+                .get_block::<TripleIndirectBlock>(inode.triple_indirect as usize)
+                .unwrap();
+            for double_indirect_block_index in triple_indirect.block.double_indirect {
+                if let Some(double_indirect) =
+                    self.get_block::<DoubleIndirectBlock>(double_indirect_block_index as usize)
+                {
+                    for indirect_block_index in double_indirect.block.indirect {
+                        if let Some(indirect) =
+                            self.get_block::<IndirectBlock>(indirect_block_index as usize)
+                        {
+                            for block_index in indirect.block.entries {
+                                self.data_bitmap.deallocate(block_index as usize);
+                            }
+                            self.data_bitmap.deallocate(indirect_block_index as usize);
+                        }
+                    }
+                    self.data_bitmap
+                        .deallocate(double_indirect_block_index as usize);
+                }
+            }
+            self.data_bitmap.deallocate(inode.triple_indirect as usize);
+        }
+
+        Ok(())
+    }
+
+    /// 从 inode 中删去最后一个 block
+    pub(crate) fn deallocate_block_for(&mut self, inode: &mut Inode) -> Option<u32> {
+        // 如果 triple indirect 块存在, 则尝试从中销毁一个块
+        if self.data_bitmap.query(inode.triple_indirect as usize) {
+            if let Some(block_index) = self.deallocate_from_triple_indirect(inode.triple_indirect) {
+                inode.n_blocks -= 1;
+                return Some(block_index); // 销毁成功, 直接返回
+            } else {
+                // 销毁失败, 说明 triple indirect 空了, 把它也销毁.
+                self.data_bitmap.deallocate(inode.triple_indirect as usize);
+                inode.triple_indirect = 0; // 这个地方理论上应该不用?
+            }
+        }
+        // 如果 double indirect 块存在, 则从其中销毁
+        if self.data_bitmap.query(inode.double_indirect as usize) {
+            if let Some(block_index) = self.deallocate_from_double_indirect(inode.double_indirect) {
+                inode.n_blocks -= 1;
+                return Some(block_index);
+            } else {
+                self.data_bitmap.deallocate(inode.double_indirect as usize);
+                inode.double_indirect = 0; // 这个地方理论上应该不用?
+            }
+        }
+        // 如果 indirect 块存在, 则从其中销毁
+        if self.data_bitmap.query(inode.single_indirect as usize) {
+            if let Some(block_index) = self.deallocate_from_indirect(inode.single_indirect) {
+                inode.n_blocks -= 1;
+                return Some(block_index);
+            } else {
+                self.data_bitmap.deallocate(inode.single_indirect as usize);
+                inode.single_indirect = 0; // 这个地方理论上应该不用?
+            }
+        }
+        // 都没有，直接从 direct 块中销毁
+        for entry in inode.direct.iter_mut().rev() {
+            if self.data_bitmap.query(*entry as usize) {
+                let index = std::mem::replace(entry, 0); // let index = *entry; *entry = 0;
+                inode.n_blocks -= 1;
+                self.data_bitmap.deallocate(index as usize);
+                return Some(index);
+            }
+        }
+        None
+    }
+
+    fn deallocate_from_triple_indirect(&mut self, triple_indirect_entry: u32) -> Option<u32> {
+        let triple_indirect_entry = triple_indirect_entry as usize;
+        if let Some(triple_indirect_block) = self
+            .get_block(triple_indirect_entry)
+            .map(convert::<DataBlock, TripleIndirectBlock>)
+        {
+            let mut triple_indirect_block = triple_indirect_block.clone();
+            let mut block_modified = false;
+            for double_indirect_entry in
+                triple_indirect_block.block.double_indirect.iter_mut().rev()
+            {
+                // 如果这个位置的 double indirect 存在
+                if self.data_bitmap.query(*double_indirect_entry as usize) {
+                    // 尝试从中销毁一个块
+                    if let Some(block_index) =
+                        self.deallocate_from_double_indirect(*double_indirect_entry)
+                    {
+                        if block_modified {
+                            self.update_block(triple_indirect_block);
+                        }
+                        return Some(block_index); // 成功则直接返回
+                    } else {
+                        // 失败则把这个 double indirect 销毁
+                        let double_indirect_entry_to_deallocate =
+                            std::mem::replace(double_indirect_entry, 0);
+                        self.data_bitmap
+                            .deallocate(double_indirect_entry_to_deallocate as usize);
+                        triple_indirect_block.dirty = true;
+                        block_modified = true;
+                    }
+                }
+            }
+            if block_modified {
+                self.update_block(triple_indirect_block);
+            }
+        }
+        None
+    }
+
+    fn deallocate_from_double_indirect(&mut self, double_indirect_entry: u32) -> Option<u32> {
+        let double_indirect_entry = double_indirect_entry as usize;
+        if let Some(double_indirect_block) = self
+            .get_block(double_indirect_entry)
+            .map(convert::<DataBlock, DoubleIndirectBlock>)
+        {
+            let mut double_indirect_block = double_indirect_block.clone();
+            let mut block_modified = false;
+            for indirect_entry in double_indirect_block.block.indirect.iter_mut().rev() {
+                // 如果这个位置的 indirect 存在
+                if self.data_bitmap.query(*indirect_entry as usize) {
+                    // 尝试从中销毁一个块
+                    if let Some(block_index) = self.deallocate_from_indirect(*indirect_entry) {
+                        if block_modified {
+                            self.update_block(double_indirect_block);
+                        }
+                        return Some(block_index); // 成功则直接返回
+                    } else {
+                        // 失败则把这个 indirect 销毁
+                        let indirect_entry_to_deallocate = std::mem::replace(indirect_entry, 0);
+                        self.data_bitmap
+                            .deallocate(indirect_entry_to_deallocate as usize);
+                        double_indirect_block.dirty = true;
+                        block_modified = true;
+                    }
+                }
+            }
+            if block_modified {
+                self.update_block(double_indirect_block);
+            }
+        }
+        None
+    }
+
+    fn deallocate_from_indirect(&mut self, indirect_entry: u32) -> Option<u32> {
+        let indirect_entry = indirect_entry as usize;
+        if let Some(indirect_block) = self
+            .get_block(indirect_entry)
+            .map(convert::<DataBlock, IndirectBlock>)
+        {
+            let mut indirect_block = indirect_block.clone();
+            // 遍历 indirect block 里的每个 block
+            for entry in indirect_block.block.entries.iter_mut().rev() {
+                // 如果这个 block 存在, 销毁它
+                if self.data_bitmap.query(*entry as usize) {
+                    let entry_to_deallocate = std::mem::replace(entry, 0);
+
+                    self.data_bitmap.deallocate(entry_to_deallocate as usize);
+                    indirect_block.dirty = true;
+                    self.update_block(indirect_block);
+
+                    return Some(entry_to_deallocate);
+                }
+            }
+        }
+        None
+    }
+}
+
+impl AyaFS {
+    pub(crate) fn get_block_index(
+        &mut self,
+        inode: &Inode,
+        mut block_index_within_inode: usize,
+    ) -> Option<usize> {
+        debug!(
+            "get_block_index(block_index_within_inode: {})",
+            block_index_within_inode
+        );
+        // direct block
+        if block_index_within_inode < DIRECT_NUMBER {
+            let block_index = inode.direct[block_index_within_inode] as usize;
+            debug!("  get_block_index -> direct");
+            return if self.data_bitmap.query(block_index) {
+                debug!("  get_block_index -> direct -> ✓");
+                Some(block_index)
+            } else {
+                debug!("  get_block_index -> direct -> ×");
+                None
+            };
+        } else {
+            block_index_within_inode -= DIRECT_NUMBER;
+        }
+
+        // indirect block
+        let indirect_number = ENTRY_PER_BLOCK;
+        if block_index_within_inode < indirect_number {
+            return if let Some(indirect_block) =
+                self.get_block::<IndirectBlock>(inode.single_indirect as usize)
+            {
+                debug!("  get_block_index -> indirect");
+                let block_index = indirect_block.block.entries[block_index_within_inode] as usize;
+                if self.data_bitmap.query(block_index) {
+                    debug!("  get_block_index -> indirect -> ✓");
+                    Some(block_index)
+                } else {
+                    debug!("  get_block_index -> indirect -> ×");
+                    None
+                }
+            } else {
+                debug!("  get_block_index -> indirect -> ×");
+                None
+            };
+        } else {
+            block_index_within_inode -= indirect_number;
+        }
+
+        // double indirect block
+        let double_indirect_number = ENTRY_PER_BLOCK * ENTRY_PER_BLOCK;
+        if block_index_within_inode < double_indirect_number {
+            if let Some(double_indirect_block) =
+                self.get_block::<DoubleIndirectBlock>(inode.double_indirect as usize)
+            {
+                debug!("  get_block_index -> double_indirect");
+                // 取出 double indirect block
+                let indirect_block_index = double_indirect_block.block.indirect
+                    [block_index_within_inode / ENTRY_PER_BLOCK]
+                    as usize;
+                // 要找的 entry 在 double indirect block 中的第几个 indirect block
+                if let Some(indirect_block) = self.get_block::<IndirectBlock>(indirect_block_index)
+                {
+                    debug!("  get_block_index -> double_indirect -> indirect");
+                    let block_index = indirect_block.block.entries
+                        [block_index_within_inode % ENTRY_PER_BLOCK]
+                        as usize;
+                    // 拿到 DirectoryBlock 的 index
+                    return if self.data_bitmap.query(block_index) {
+                        debug!("  get_block_index -> double_indirect -> indirect -> ✓");
+                        Some(block_index)
+                    } else {
+                        debug!("  get_block_index -> double_indirect -> indirect -> ×");
+                        None
+                    };
+                }
+            }
+            return None;
+        } else {
+            block_index_within_inode -= double_indirect_number;
+        }
+
+        // triple indirect block
+        if let Some(triple_indirect_block) =
+            self.get_block::<TripleIndirectBlock>(inode.triple_indirect as usize)
+        {
+            // 取出 triple indirect block
+            let double_indirect_block_index = triple_indirect_block.block.double_indirect
+                [block_index_within_inode / (ENTRY_PER_BLOCK * ENTRY_PER_BLOCK)]
+                as usize;
+            // 要找的 entry 在 triple indirect block 中的第几个 double indirect block
+            if let Some(double_indirect_block) =
+                self.get_block::<DoubleIndirectBlock>(double_indirect_block_index)
+            {
+                // 取出 double indirect block
+                let indirect_block_index = double_indirect_block.block.indirect
+                    [block_index_within_inode % (ENTRY_PER_BLOCK * ENTRY_PER_BLOCK)
+                        / ENTRY_PER_BLOCK] as usize;
+                // 要找的 entry 在 double indirect block 中的第几个 indirect block
+                if let Some(indirect_block) = self.get_block::<IndirectBlock>(indirect_block_index)
+                {
+                    let block_index = indirect_block.block.entries
+                        [block_index_within_inode % ENTRY_PER_BLOCK]
+                        as usize;
+                    // DirectoryBlock 的 index
+                    return if self.data_bitmap.query(block_index) {
+                        Some(block_index)
+                    } else {
+                        None
+                    };
+                }
+            }
+        }
+
+        None
+    }
+
+    pub(crate) fn access_block<T: Block>(
+        &mut self,
+        inode: &Inode,
+        block_index_within_inode: usize,
+    ) -> Option<&CachedBlock<T>> {
+        self.get_block_index(inode, block_index_within_inode)
+            .map(|block_index| {
+                self.get_block::<T>(block_index).unwrap() // 可以 unwrap 吧这里 ??
+            })
+    }
+
+    pub(crate) fn access_block_mut<T: Block>(
+        &mut self,
+        inode: &Inode,
+        block_index_within_inode: usize,
+    ) -> Option<&mut CachedBlock<T>> {
+        self.get_block_index(inode, block_index_within_inode)
+            .map(|block_index| {
+                debug!(
+                    "access_block_mut(index: {}) found",
+                    block_index_within_inode
+                );
+                self.get_block_mut::<T>(block_index).unwrap() // 可以 unwrap 吧这里 ??
+            })
+    }
+}
diff --git a/ayafs-core/src/disk/bitmap.rs b/ayafs-core/src/disk/bitmap.rs
new file mode 100644
index 0000000..b68c341
--- /dev/null
+++ b/ayafs-core/src/disk/bitmap.rs
@@ -0,0 +1,48 @@
+use crate::block_device::{BlockDevice, BLOCK_SIZE};
+use std::sync::Arc;
+
+pub struct Bitmap {
+    pub starting_block: usize,
+    pub length: usize,
+    pub device: Arc<dyn BlockDevice>,
+    pub data: Vec<u8>,
+}
+
+impl Bitmap {
+    pub(crate) fn new(starting_block: usize, length: usize, device: Arc<dyn BlockDevice>) -> Self {
+        Self {
+            starting_block,
+            length,
+            device,
+            data: vec![0u8; length * BLOCK_SIZE],
+        }
+    }
+    pub(crate) fn allocate(&mut self) -> Option<usize> {
+        for (i, byte) in self.data.iter_mut().enumerate() {
+            let leading_ones = byte.leading_ones();
+            if leading_ones != 8 {
+                *byte |= (1 << (7 - leading_ones)) as u8;
+                return Some(i * 8 + leading_ones as usize);
+            }
+        }
+        None
+    }
+
+    pub(crate) fn query(&self, index: usize) -> bool {
+        if index == 0 {
+            false
+        } else {
+            self.data[index / 8] & ((1 << (7 - index % 8)) as u8) != 0
+        }
+    }
+
+    pub(crate) fn deallocate(&mut self, index: usize) -> bool {
+        if self.query(index) {
+            let mask = !(1u8 << (7 - index % 8));
+            self.data[index / 8] &= mask;
+            true
+        } else {
+            false
+        }
+    }
+}
diff --git a/ayafs-core/src/disk/block.rs b/ayafs-core/src/disk/block.rs
new file mode 100644
index 0000000..76769b9
--- /dev/null
+++ b/ayafs-core/src/disk/block.rs
@@ -0,0 +1,271 @@
+use crate::disk::inode::Inode;
+use std::ffi::{OsStr, OsString};
+use std::os::unix::ffi::OsStrExt;
+
+pub trait Block: Default + Clone {}
+
+#[repr(C)]
+pub struct SuperBlock {
+    pub(crate) data_bitmap_block_number: u64,
+    pub(crate) inode_bitmap_block_number: u64,
+    pub(crate) inode_block_number: u64,
+    pub(crate) data_block_number: u64,
+    padding: [u8; 4064],
+}
+
+impl SuperBlock {
+    pub(crate) fn new(
+        data_bitmap_block_number: usize,
+        inode_bitmap_block_number: usize,
+        inode_block_number: usize,
+        data_block_number: usize,
+    ) -> Self {
+        Self {
+            data_bitmap_block_number: data_bitmap_block_number as u64,
+            inode_bitmap_block_number: inode_bitmap_block_number as u64,
+            inode_block_number: inode_block_number as u64,
+            data_block_number: data_block_number as u64,
+            padding: [0; 4064],
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct DataBlock(pub(crate) [u8; 4096]);
+
+impl Default for DataBlock {
+    fn default() -> Self {
+        Self([0; 4096])
+    }
+}
+
+impl Block for DataBlock {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct InodeBlock {
+    pub(crate) inodes: [Inode; 32],
+}
+
+impl Default for InodeBlock {
+    fn default() -> Self {
+        Self {
+            inodes: [
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+                Inode::empty(),
+            ],
+        }
+    }
+}
+
+impl Block for InodeBlock {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct DirectoryEntry {
+    pub inode: u32,
+    pub record_len: u16,
+    pub name_len: u8,
+    pub file_type: u8,
+    pub name: [u8; 256],
+}
+
+impl DirectoryEntry {
+    pub(crate) fn name(&self) -> OsString {
+        let name = &self.name[0..self.name_len as usize];
+        OsStr::from_bytes(name).to_os_string()
+    }
+}
+
+impl Default for DirectoryEntry {
+    fn default() -> Self {
+        Self {
+            inode: 0,
+            record_len: 0,
+            name_len: 0,
+            file_type: 0x0,
+            name: [0; 256],
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct DirectoryBlock {
+    pub entries: [DirectoryEntry; 15],
+    pub occupancy: [u8; 2],
+    reserved: [u8; 134],
+}
+
+impl Default for DirectoryBlock {
+    fn default() -> Self {
+        Self {
+            entries: [
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+                DirectoryEntry::default(),
+            ],
+            occupancy: [0x80, 0x00], // 0b1000_0000
+            reserved: [0xFF; 134],
+        }
+    }
+}
+
+impl DirectoryBlock {
+    #[allow(unused)]
+    pub(crate) fn is_full(&self) -> bool {
+        self.occupancy[0] == 0xFF && self.occupancy[1] == 0xFF
+    }
+
+    pub(crate) fn query(&self, mut index: usize) -> bool {
+        if index < 7 {
+            // 0-6, first u8
+            index = index + 1;
+            self.occupancy[0] & (1 << (7 - index)) as u8 != 0
+        } else if index < 15 {
+            // 7-14, second u8
+            index = index - 7;
+            self.occupancy[1] & (1 << (7 - index)) as u8 != 0
+        } else {
+            false
+        }
+    }
+
+    pub(crate) fn allocate(&mut self, mut index: usize) -> bool {
+        if index < 7 {
+            index = index + 1;
+            let mask = (1 << (7 - index)) as u8;
+            if self.occupancy[0] & mask != 0 {
+                false
+            } else {
+                self.occupancy[0] |= mask;
+                true
+            }
+        } else {
+            index = index - 7;
+            let mask = (1 << (7 - index)) as u8;
+            if self.occupancy[1] & mask != 0 {
+                false
+            } else {
+                self.occupancy[1] |= mask;
+                true
+            }
+        }
+    }
+
+    // pub(crate) fn allocate(&mut self) -> Option<usize> {
+    //     if self.occupancy[0] != 0xFF {
+    //         let leading_ones = self.occupancy[0].leading_ones();
+    //         self.occupancy[0] |= (1 << (7 - leading_ones)) as u8;
+    //         Some(leading_ones as usize)
+    //     } else if self.occupancy[1] != 0xFF {
+    //         let leading_ones = self.occupancy[1].leading_ones();
+    //         self.occupancy[1] |= (1 << (7 - leading_ones)) as u8;
+    //         Some(7 + leading_ones as usize)
+    //     } else {
+    //         None
+    //     }
+    // }
+
+    pub(crate) fn deallocate(&mut self, mut index: usize) {
+        if index < 7 {
+            index = index + 1;
+            self.occupancy[0] &= !((1 << (7 - index)) as u8);
+        } else if index < 15 {
+            // 7-14, second u8
+            index = index - 7;
+            self.occupancy[1] &= !((1 << (7 - index)) as u8);
+        }
+    }
+}
+
+impl Block for DirectoryBlock {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct IndirectBlock {
+    pub entries: [u32; 1024],
+}
+
+impl Default for IndirectBlock {
+    fn default() -> Self {
+        Self { entries: [0; 1024] }
+    }
+}
+
+impl Block for IndirectBlock {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct DoubleIndirectBlock {
+    pub indirect: [u32; 1024],
+}
+
+impl Default for DoubleIndirectBlock {
+    fn default() -> Self {
+        Self {
+            indirect: [0; 1024],
+        }
+    }
+}
+
+impl Block for DoubleIndirectBlock {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct TripleIndirectBlock {
+    pub double_indirect: [u32; 1024],
+}
+
+impl Default for TripleIndirectBlock {
+    fn default() -> Self {
+        Self {
+            double_indirect: [0; 1024],
+        }
+    }
+}
+
+impl Block for TripleIndirectBlock {}
diff --git a/ayafs-core/src/disk/inode.rs b/ayafs-core/src/disk/inode.rs
new file mode 100644
index 0000000..d94b795
--- /dev/null
+++ b/ayafs-core/src/disk/inode.rs
@@ -0,0 +1,312 @@
+use crate::block_device::BLOCK_SIZE;
+use crate::utils;
+use bitflags::bitflags;
+use fuser::FileType;
+
+pub const DIRECT_NUMBER: usize = 15;
+
+#[derive(Debug, Clone, Copy)]
+pub struct InodeMode(pub u16);
+
+bitflags! {
+    impl InodeMode: u16 {
+        const IXOTH = 0x0001;
+        const IWOTH = 0x0002;
+        const IROTH = 0x0004;
+        const IXGRP = 0x0008;
+        const IWGRP = 0x0010;
+        const IRGRP = 0x0020;
+        const IXUSR = 0x0040;
+        const IWUSR = 0x0080;
+        const IRUSR = 0x0100;
+        const ISVTX = 0x0200;
+        const ISGID = 0x0400;
+        const ISUID = 0x0800;
+        // These are mutually-exclusive:
+        const IFIFO = 0x1000;
+        const IFCHR = 0x2000;
+        const IFDIR = 0x4000;
+        const IFBLK = 0x6000;
+        const IFREG = 0x8000;
+        const IFLNK = 0xA000;
+        const IFSOCK = 0xC000;
+    }
+}
+
+impl InodeMode {
+    #[allow(unused)]
+    pub(crate) fn exec_other(&self) -> bool {
+        self.0 & Self::IXOTH.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn write_other(&self) -> bool {
+        self.0 & Self::IWOTH.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn read_other(&self) -> bool {
+        self.0 & Self::IROTH.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn exec_group(&self) -> bool {
+        self.0 & Self::IXGRP.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn write_group(&self) -> bool {
+        self.0 & Self::IWGRP.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn read_group(&self) -> bool {
+        self.0 & Self::IRGRP.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn exec_user(&self) -> bool {
+        self.0 & Self::IXUSR.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn write_user(&self) -> bool {
+        self.0 & Self::IWUSR.0 != 0
+    }
+    #[allow(unused)]
+    pub(crate) fn read_user(&self) -> bool {
+        self.0 & Self::IRUSR.0 != 0
+    }
+
+    pub(crate) fn perm(&self) -> u16 {
+        self.0 & 0x0FFF
+    }
+
+    pub(crate) fn is_file(&self) -> bool {
+        (self.0 & 0xF000) == Self::IFREG.0
+    }
+
+    pub(crate) fn is_dir(&self) -> bool {
+        (self.0 & 0xF000) == Self::IFDIR.0
+    }
+
+    pub(crate) fn is_symlink(&self) -> bool {
+        self.0 & 0xF000 == Self::IFLNK.0
+    }
+
+    pub(crate) fn validate(mode_value: u16) -> Option<Self> {
+        let valid_flags: [u16; 7] = [0x1000, 0x2000, 0x4000, 0x6000, 0x8000, 0xA000, 0xC000];
+        valid_flags
+            .contains(&(mode_value & 0xF000))
+            .then(|| Self(mode_value))
+    }
+}
+
+impl From<InodeMode> for FileType {
+    fn from(value: InodeMode) -> Self {
+        let type_flag = value.0 & 0xF000;
+        match type_flag {
+            0x1000 => FileType::NamedPipe,
+            0x2000 => FileType::CharDevice,
+            0x4000 => FileType::Directory,
+            0x6000 => FileType::BlockDevice,
+            0x8000 => FileType::RegularFile,
+            0xA000 => FileType::Symlink,
+            0xC000 => FileType::Socket,
+            _ => panic!("Invalid inode mode {:x}", type_flag),
+        }
+    }
+}
+
+impl From<InodeMode> for u8 {
+    fn from(value: InodeMode) -> Self {
+        utils::from_filetype(value.into())
+    }
+}
+
+/// Pretty much the same with ext2, with minor changes:
+/// - removed OS dependent attributes (osd1 & osd2)
+/// - removed i_faddr since fragmentation is not supported
+/// - changed uid and gid from u16 to u32
+/// - added more direct blocks for a total size of 128 bytes
+/// TODO: do we need to extend time precision?
+#[repr(C)]
+#[derive(Debug, Clone)]
+pub struct Inode {
+    pub mode: InodeMode,
+    pub uid: u32,
+    pub size: u32,
+    pub atime: u32,  // access time, in seconds
+    pub ctime: u32,  // change time, in seconds
+    pub mtime: u32,  // modify time, in seconds
+    pub crtime: u32, // create time, in seconds
+    pub gid: u32,
+    pub n_links: u16,
+    pub n_blocks: u32,
+    pub flags: u32, // TODO: do we actually need this? maybe just return 0
+    pub direct: [u32; DIRECT_NUMBER],
+    pub single_indirect: u32,
+    pub double_indirect: u32,
+    pub triple_indirect: u32,
+    pub generation: u32,
+    pub file_acl: u32,
+    pub dir_acl: u32, // TODO do we have to implement ACL......?
+}
+
+impl Inode {
+    fn new(
+        mode: InodeMode,
+        uid: u32,
+        gid: u32,
+        time: u32,
+        flags: u32,
+        generation: u32,
+        file_acl: u32,
+        dir_acl: u32,
+    ) -> Self {
+        Self {
+            mode,
+            uid,
+            size: 0,
+            atime: time,
+            ctime: time,
+            mtime: time,
+            crtime: time,
+            gid,
+            n_links: 1,
+            n_blocks: 0,
+            flags,
+            direct: [0; DIRECT_NUMBER],
+            single_indirect: 0,
+            double_indirect: 0,
+            triple_indirect: 0,
+            generation,
+            file_acl,
+            dir_acl,
+        }
+    }
+
+    #[allow(unused)]
+    pub fn make_inode(
+        permissions: u16,
+        mode: InodeMode,
+        uid: u32,
+        gid: u32,
+        time: u32,
+        flags: u32,
+        generation: u32,
+        file_acl: u32,
+        dir_acl: u32,
+    ) -> Self {
+        Self::new(
+            InodeMode(permissions) | mode,
+            uid,
+            gid,
+            time,
+            flags,
+            generation,
+            file_acl,
+            dir_acl,
+        )
+    }
+
+    pub fn directory(
+        permissions: u16,
+        uid: u32,
+        gid: u32,
+        time: u32,
+        flags: u32,
+        generation: u32,
+        file_acl: u32,
+        dir_acl: u32,
+    ) -> Self {
+        Self::new(
+            InodeMode(permissions) | InodeMode::IFDIR,
+            uid,
+            gid,
+            time,
+            flags,
+            generation,
+            file_acl,
+            dir_acl,
+        )
+    }
+
+    pub fn file(
+        permissions: u16,
+        uid: u32,
+        gid: u32,
+        time: u32,
+        flags: u32,
+        generation: u32,
+        file_acl: u32,
+        dir_acl: u32,
+    ) -> Self {
+        Self::new(
+            InodeMode(permissions) | InodeMode::IFREG,
+            uid,
+            gid,
+            time,
+            flags,
+            generation,
+            file_acl,
+            dir_acl,
+        )
+    }
+
+    pub fn symlink(
+        permissions: u16,
+        uid: u32,
+        gid: u32,
+        time: u32,
+        flags: u32,
+        generation: u32,
+        file_acl: u32,
+        dir_acl: u32,
+    ) -> Self {
+        Self::new(
+            InodeMode(permissions) | InodeMode::IFLNK,
+            uid,
+            gid,
+            time,
+            flags,
+            generation,
+            file_acl,
+            dir_acl,
+        )
+    }
+
+    pub(crate) fn is_file(&self) -> bool {
+        self.mode.is_file()
+    }
+
+    pub(crate) fn is_dir(&self) -> bool {
+        self.mode.is_dir()
+    }
+
+    pub(crate) fn is_symlink(&self) -> bool {
+        self.mode.is_symlink()
+    }
+
+    pub(crate) fn file_type(&self) -> FileType {
+        self.mode.into()
+    }
+
+    pub fn empty() -> Self {
+        Self {
+            mode: InodeMode(0),
+            uid: 0,
+            size: 0,
+            atime: 0,
+            ctime: 0,
+            mtime: 0,
+            crtime: 0,
+            gid: 0,
+            n_links: 0,
+            n_blocks: 0,
+            flags: 0,
+            direct: [0; 15],
+            single_indirect: 0,
+            double_indirect: 0,
+            triple_indirect: 0,
+            generation: 0,
+            file_acl: 0,
+            dir_acl: 0,
+        }
+    }
+}
+pub const INODE_SIZE: usize = std::mem::size_of::<Inode>();
+pub const ENTRY_PER_BLOCK: usize = BLOCK_SIZE / 4;
diff --git a/ayafs-core/src/disk/mod.rs b/ayafs-core/src/disk/mod.rs
new file mode 100644
index 0000000..878e832
--- /dev/null
+++ b/ayafs-core/src/disk/mod.rs
@@ -0,0 +1,6 @@
+pub mod allocation;
+/// On-disk data structures and logic.
+/// Including bitmaps, inodes and blocks.
+pub mod bitmap;
+pub mod block;
+pub mod inode;