fs/ext2: indirect block reading

kernel/driver/fs/ext2/src/data.rs

@@ -0,0 +1,218 @@
+use core::ops::{Deref, DerefMut};
+
+use alloc::{boxed::Box, vec};
+use bytemuck::{Pod, Zeroable};
+use libk::vfs::Metadata;
+use static_assertions::const_assert_eq;
+use yggdrasil_abi::io::{FileMode, FileType, GroupId, UserId};
+
+use crate::Ext2Fs;
+
+pub const SUPERBLOCK_OFFSET: u64 = 1024;
+pub const EXT2_SIGNATURE: u16 = 0xEF53;
+pub const ROOT_INODE: u32 = 2;
+
+pub const DIRECT_BLOCK_COUNT: usize = 12;
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(transparent)]
+pub struct InodeMode(u16);
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(C)]
+pub struct Superblock {
+    pub total_inodes: u32,
+    pub total_blocks: u32,
+    pub root_reserved_blocks: u32,
+    pub total_unallocated_blocks: u32,
+    pub total_unallocated_inodes: u32,
+    pub superblock_number: u32,
+    pub block_size_log2: u32,
+    pub fragment_size_log2: u32,
+    pub block_group_block_count: u32,
+    pub block_group_fragment_count: u32,
+    pub block_group_inode_count: u32,
+    pub last_mount_time: u32,
+    pub last_written_time: u32,
+    pub mounts_since_fsck: u16,
+    pub mounts_allowed_between_fsck: u16,
+    pub signature: u16,
+    pub state: u16,
+    pub error_behavior: u16,
+    pub version_minor: u16,
+    pub last_fsck_time: u32,
+    pub fsck_interval: u32,
+    pub creator_os_id: u32,
+    pub version_major: u32,
+    pub root_user_id: u16,
+    pub root_group_id: u16,
+}
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(C)]
+pub struct ExtendedSuperblock {
+    pub base: Superblock,
+    pub first_non_reserved_inode: u32,
+    pub inode_struct_size: u16,
+    pub superblock_block_group_number: u16,
+    pub optional_features: u32,
+    pub required_features: u32,
+    pub readonly_features: u32,
+    pub filesystem_id: [u8; 16],
+    pub volume_name: [u8; 16],
+    pub last_mount_path: [u8; 64],
+    pub compression_algorithms: u32,
+    pub file_prealloc_block_count: u8,
+    pub directory_prealloc_block_count: u8,
+    _0: u16,
+    pub journal_id: [u8; 16],
+    pub journal_inode: u32,
+    pub journal_device: u32,
+    pub orphan_inode_list_head: u32,
+}
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(C)]
+pub struct BlockGroupDescriptor {
+    pub block_usage_bitmap: u32,
+    pub inode_usage_bitmap: u32,
+    pub inode_table: u32,
+    pub unallocated_blocks: u16,
+    pub unallocated_inodes: u16,
+    pub unallocated_directories: u16,
+    _0: [u8; 14],
+}
+
+pub struct BlockGroupDescriptorTable {
+    pub(crate) data: Box<[u8]>,
+    pub(crate) len: usize,
+}
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(C)]
+pub struct Inode {
+    pub mode: InodeMode,
+    pub uid: u16,
+    pub size_lower: u32,
+    pub atime: u32,
+    pub ctime: u32,
+    pub mtime: u32,
+    pub dtime: u32,
+    pub gid: u16,
+    pub hard_links: u16,
+    pub sector_count: u32,
+    pub flags: u32,
+    pub os_val1: u32,
+    pub direct_blocks: [u32; DIRECT_BLOCK_COUNT],
+    pub indirect_block_l1: u32,
+    pub indirect_block_l2: u32,
+    pub indirect_block_l3: u32,
+    pub generation: u32,
+    pub facl: u32,
+    pub size_upper: u32,
+    pub frag_block_no: u32,
+    pub os_val2: u32,
+}
+
+#[derive(Debug, Clone, Copy, Pod, Zeroable)]
+#[repr(C)]
+pub struct Dirent {
+    pub ino: u32,
+    pub ent_size: u16,
+    pub name_length_low: u8,
+    pub type_indicator: u8,
+}
+
+impl BlockGroupDescriptorTable {
+    pub fn with_capacity(size: usize, len: usize) -> Self {
+        let data = vec![0; size].into_boxed_slice();
+        Self { data, len }
+    }
+
+    pub fn descriptor(&self, index: u32) -> &BlockGroupDescriptor {
+        let index = index as usize;
+        if index >= self.len {
+            panic!();
+        }
+        bytemuck::from_bytes(
+            &self.data[index * size_of::<BlockGroupDescriptor>()
+                ..(index + 1) * size_of::<BlockGroupDescriptor>()],
+        )
+    }
+}
+
+const_assert_eq!(size_of::<BlockGroupDescriptor>(), 32);
+
+impl ExtendedSuperblock {
+    pub fn inode_size(&self) -> usize {
+        if self.base.version_major != 0 {
+            self.inode_struct_size as _
+        } else {
+            128
+        }
+    }
+
+    pub fn required_features(&self) -> u32 {
+        if self.base.version_major != 0 {
+            self.required_features
+        } else {
+            todo!()
+        }
+    }
+}
+
+impl Deref for ExtendedSuperblock {
+    type Target = Superblock;
+
+    fn deref(&self) -> &Self::Target {
+        &self.base
+    }
+}
+
+impl DerefMut for ExtendedSuperblock {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.base
+    }
+}
+
+impl Inode {
+    pub fn blocks(&self, fs: &Ext2Fs) -> usize {
+        (self.size_lower as usize + fs.block_size - 1) / fs.block_size
+    }
+
+    pub fn user_id(&self) -> UserId {
+        unsafe { UserId::from_raw(self.uid as _) }
+    }
+
+    pub fn group_id(&self) -> GroupId {
+        unsafe { GroupId::from_raw(self.uid as _) }
+    }
+
+    pub fn metadata(&self) -> Metadata {
+        Metadata {
+            uid: self.user_id(),
+            gid: self.group_id(),
+            mode: self.mode.permissions(),
+        }
+    }
+}
+
+impl InodeMode {
+    pub fn node_type(&self) -> Option<FileType> {
+        match self.0 & 0xF000 {
+            0x4000 => Some(FileType::Directory),
+            0x8000 => Some(FileType::File),
+            _ => todo!(),
+        }
+    }
+
+    pub fn permissions(&self) -> FileMode {
+        unsafe { FileMode::from_raw(self.0 as u32 & 0o777) }
+    }
+}
+
+impl From<InodeMode> for u16 {
+    fn from(value: InodeMode) -> Self {
+        value.0
+    }
+}

kernel/driver/fs/ext2/src/dir.rs

@@ -7,7 +7,7 @@ use libk::{
     vfs::{CommonImpl, DirectoryImpl, DirectoryOpenPosition, Metadata, Node, NodeFlags, NodeRef},
 };
 use yggdrasil_abi::{
-    io::{DirectoryEntry, FileMode, FileType, GroupId, UserId},
+    io::{DirectoryEntry, FileType},
     util::FixedString,
 };
 
@@ -158,11 +158,7 @@ impl CommonImpl for DirectoryNode {
     }
 
     fn metadata(&self, _node: &NodeRef) -> Result<Metadata, Error> {
-        Ok(Metadata {
-            uid: unsafe { UserId::from_raw(self.inode.uid as _) },
-            gid: unsafe { GroupId::from_raw(self.inode.gid as _) },
-            mode: unsafe { FileMode::from_raw(self.inode.mode as u32 & 0o777) },
-        })
+        Ok(self.inode.metadata())
     }
 }
 

kernel/driver/fs/ext2/src/file.rs

@@ -6,7 +6,7 @@ use libk::{
     error::Error,
     vfs::{CommonImpl, InstanceData, Metadata, Node, NodeFlags, NodeRef, RegularImpl},
 };
-use yggdrasil_abi::io::{FileMode, GroupId, OpenOptions, UserId};
+use yggdrasil_abi::io::OpenOptions;
 
 use crate::{Ext2Fs, Inode};
 
@@ -55,11 +55,7 @@ impl RegularNode {
 
 impl CommonImpl for RegularNode {
     fn metadata(&self, _node: &NodeRef) -> Result<Metadata, Error> {
-        Ok(Metadata {
-            uid: unsafe { UserId::from_raw(self.inode.uid as _) },
-            gid: unsafe { GroupId::from_raw(self.inode.gid as _) },
-            mode: unsafe { FileMode::from_raw(self.inode.mode as u32 & 0o777) },
-        })
+        Ok(self.inode.metadata())
     }
 
     fn as_any(&self) -> &dyn Any {

kernel/driver/fs/ext2/src/lib.rs

@@ -2,10 +2,8 @@
 
 extern crate alloc;
 
-use core::ops::{Deref, DerefMut};
-
-use alloc::{boxed::Box, sync::Arc, vec};
-use bytemuck::{Pod, Zeroable};
+use alloc::sync::Arc;
+use bytemuck::Zeroable;
 use dir::DirectoryNode;
 use file::RegularNode;
 use libk::{
@@ -19,14 +17,15 @@ use libk::{
     },
 };
 use libk_util::OneTimeInit;
-use static_assertions::const_assert_eq;
 
+mod data;
 pub mod dir;
 pub mod file;
 
-pub const SUPERBLOCK_OFFSET: u64 = 1024;
-pub const EXT2_SIGNATURE: u16 = 0xEF53;
-pub const BGDT_BLOCK_NUMBER: u32 = 2;
+pub use data::{
+    BlockGroupDescriptor, BlockGroupDescriptorTable, Dirent, ExtendedSuperblock, Inode, Superblock,
+};
+use yggdrasil_abi::io::FileType;
 
 pub struct Ext2Fs {
     cache: BlockCache,
@@ -37,169 +36,11 @@ pub struct Ext2Fs {
     inode_size: usize,
     block_size: usize,
     inodes_per_block: usize,
+    pointers_per_block: usize,
 
     root: OneTimeInit<NodeRef>,
 }
 
-#[derive(Debug, Clone, Copy, Pod, Zeroable)]
-#[repr(C)]
-pub struct Superblock {
-    total_inodes: u32,
-    total_blocks: u32,
-    root_reserved_blocks: u32,
-    total_unallocated_blocks: u32,
-    total_unallocated_inodes: u32,
-    superblock_number: u32,
-    block_size_log2: u32,
-    fragment_size_log2: u32,
-    block_group_block_count: u32,
-    block_group_fragment_count: u32,
-    block_group_inode_count: u32,
-    last_mount_time: u32,
-    last_written_time: u32,
-    mounts_since_fsck: u16,
-    mounts_allowed_between_fsck: u16,
-    signature: u16,
-    state: u16,
-    error_behavior: u16,
-    version_minor: u16,
-    last_fsck_time: u32,
-    fsck_interval: u32,
-    creator_os_id: u32,
-    version_major: u32,
-    root_user_id: u16,
-    root_group_id: u16,
-}
-
-#[derive(Debug, Clone, Copy, Pod, Zeroable)]
-#[repr(C)]
-pub struct ExtendedSuperblock {
-    base: Superblock,
-    first_non_reserved_inode: u32,
-    inode_struct_size: u16,
-    superblock_block_group_number: u16,
-    optional_features: u32,
-    required_features: u32,
-    readonly_features: u32,
-    filesystem_id: [u8; 16],
-    volume_name: [u8; 16],
-    last_mount_path: [u8; 64],
-    compression_algorithms: u32,
-    file_prealloc_block_count: u8,
-    directory_prealloc_block_count: u8,
-    _0: u16,
-    journal_id: [u8; 16],
-    journal_inode: u32,
-    journal_device: u32,
-    orphan_inode_list_head: u32,
-}
-
-#[derive(Debug, Clone, Copy, Pod, Zeroable)]
-#[repr(C)]
-pub struct BlockGroupDescriptor {
-    block_usage_bitmap: u32,
-    inode_usage_bitmap: u32,
-    inode_table: u32,
-    unallocated_blocks: u16,
-    unallocated_inodes: u16,
-    unallocated_directories: u16,
-    _0: [u8; 14],
-}
-
-struct BlockGroupDescriptorTable {
-    data: Box<[u8]>,
-    len: usize,
-}
-
-#[derive(Debug, Clone, Copy, Pod, Zeroable)]
-#[repr(C)]
-pub struct Inode {
-    mode: u16,
-    uid: u16,
-    size_lower: u32,
-    atime: u32,
-    ctime: u32,
-    mtime: u32,
-    dtime: u32,
-    gid: u16,
-    hard_links: u16,
-    sector_count: u32,
-    flags: u32,
-    os_val1: u32,
-    direct_blocks: [u32; 12],
-    indirect_block_l1: u32,
-    indirect_block_l2: u32,
-    indirect_block_l3: u32,
-    generation: u32,
-    facl: u32,
-    size_upper: u32,
-    frag_block_no: u32,
-    os_val2: u32,
-}
-
-#[derive(Debug, Clone, Copy, Pod, Zeroable)]
-#[repr(C)]
-pub struct Dirent {
-    ino: u32,
-    ent_size: u16,
-    name_length_low: u8,
-    type_indicator: u8,
-}
-
-pub struct BlockReader<'a> {
-    fs: &'a Ext2Fs,
-    inode: &'a Inode,
-    len: u32,
-    index: u32,
-}
-
-impl<'a> BlockReader<'a> {
-    pub fn new(fs: &'a Ext2Fs, inode: &'a Inode) -> Self {
-        let len = if inode.mode & 0xF000 == 0x4000 {
-            (inode.size_lower as u64 / fs.block_size as u64) as u32
-        } else {
-            todo!()
-        };
-        Self {
-            fs,
-            inode,
-            len,
-            index: 0,
-        }
-    }
-
-    pub async fn next(&mut self) -> Option<Result<CachedBlockRef, Error>> {
-        if self.index >= self.len {
-            return None;
-        }
-        let block = self.fs.inode_block(self.inode, self.index).await;
-        if block.is_ok() {
-            self.index += 1;
-        }
-        Some(block)
-    }
-}
-
-impl BlockGroupDescriptorTable {
-    pub fn with_capacity(size: usize, len: usize) -> Self {
-        let data = vec![0; size].into_boxed_slice();
-        Self { data, len }
-    }
-
-    pub fn descriptor(&self, index: u32) -> &BlockGroupDescriptor {
-        let index = index as usize;
-        if index >= self.len {
-            panic!();
-        }
-        bytemuck::from_bytes(
-            &self.data[index * size_of::<BlockGroupDescriptor>()
-                ..(index + 1) * size_of::<BlockGroupDescriptor>()],
-        )
-    }
-}
-
-const_assert_eq!(size_of::<BlockGroupDescriptor>(), 32);
-
 impl Ext2Fs {
     pub async fn create(device: &'static dyn BlockDevice) -> Result<NodeRef, Error> {
         let fs = Self::create_fs(device).await.map_err(|e| {
@@ -207,7 +48,7 @@ impl Ext2Fs {
             e
         })?;
         let fs = Arc::new(fs);
-        let root = fs.load_node(2).await?;
+        let root = fs.load_node(data::ROOT_INODE).await?;
 
         fs.root.init(root.clone());
 
@@ -217,20 +58,23 @@ impl Ext2Fs {
     async fn create_fs(device: &'static dyn BlockDevice) -> Result<Self, Error> {
         let mut superblock = ExtendedSuperblock::zeroed();
         device
-            .read(SUPERBLOCK_OFFSET, bytemuck::bytes_of_mut(&mut superblock))
+            .read(
+                data::SUPERBLOCK_OFFSET,
+                bytemuck::bytes_of_mut(&mut superblock),
+            )
             .await?;
 
-        if superblock.signature != EXT2_SIGNATURE {
+        if superblock.signature != data::EXT2_SIGNATURE {
             log::warn!(
                 "Invalid ext2 signature: expected {:#x}, got {:#x}",
-                EXT2_SIGNATURE,
+                data::EXT2_SIGNATURE,
                 superblock.signature
             );
             return Err(Error::InvalidArgument);
         }
 
-        let bgdt_offset = 1;
         let block_size = 1024usize << superblock.block_size_log2;
+        let bgdt_block_index = (data::SUPERBLOCK_OFFSET as usize + block_size - 1) / block_size;
 
         let bgdt_entry_count = ((superblock.total_blocks + superblock.block_group_block_count - 1)
             / superblock.block_group_block_count) as usize;
@@ -254,7 +98,7 @@ impl Ext2Fs {
             bgdt_entry_count,
         );
         for i in 0..bgdt_block_count {
-            let disk_offset = (i as u64 + bgdt_offset) * block_size as u64;
+            let disk_offset = (i + bgdt_block_index) as u64 * block_size as u64;
             device
                 .read_exact(
                     disk_offset,
@@ -269,9 +113,10 @@ impl Ext2Fs {
             block_size,
             inode_size: superblock.inode_size(),
             inodes_per_block: block_size / superblock.inode_size(),
+            pointers_per_block: block_size / size_of::<u32>(),
 
             // 128 × 8 cache
-            cache: BlockCache::with_capacity(device, block_size, 128),
+            cache: BlockCache::with_capacity(device, block_size, 512),
             superblock,
             bgdt,
 
@@ -280,12 +125,10 @@ impl Ext2Fs {
     }
 
     fn create_node(self: &Arc<Self>, inode: Inode, ino: u32) -> Result<NodeRef, Error> {
-        match inode.mode & 0xF000 {
-            // Directory
-            0x4000 => Ok(DirectoryNode::new(self.clone(), inode, ino)),
-            // Regular file
-            0x8000 => Ok(RegularNode::new(self.clone(), inode, ino)),
-            _ => todo!("Unknown file type: {:#x}", inode.mode),
+        match inode.mode.node_type() {
+            Some(FileType::Directory) => Ok(DirectoryNode::new(self.clone(), inode, ino)),
+            Some(FileType::File) => Ok(RegularNode::new(self.clone(), inode, ino)),
+            e => todo!("Unhandled inode type: {:?} ({:#x?})", e, inode.mode),
         }
     }
 
@@ -325,49 +168,58 @@ impl Ext2Fs {
         self.block(block_index).await
     }
 
+    async fn read_index(&self, block_index: u32, index: usize) -> Result<u32, Error> {
+        let block = self.block(block_index).await?;
+        let indirect: &[u32] = unsafe {
+            core::slice::from_raw_parts(&block[0] as *const _ as *const _, self.pointers_per_block)
+        };
+
+        return Ok(indirect[index]);
+    }
+
     async fn inode_block_index(&self, inode: &Inode, index: u32) -> Result<u32, Error> {
-        if index < 12 {
-            Ok(inode.direct_blocks[index as usize])
-        } else {
-            todo!()
+        let mut index = index as usize;
+        // L0
+        if index < inode.direct_blocks.len() {
+            return Ok(inode.direct_blocks[index]);
         }
-    }
-}
 
-impl ExtendedSuperblock {
-    pub fn inode_size(&self) -> usize {
-        if self.base.version_major != 0 {
-            self.inode_struct_size as _
-        } else {
-            128
+        // L1
+        index -= inode.direct_blocks.len();
+        if index < self.pointers_per_block {
+            return self.read_index(inode.indirect_block_l1, index).await;
         }
-    }
 
-    pub fn required_features(&self) -> u32 {
-        if self.base.version_major != 0 {
-            self.required_features
-        } else {
-            todo!()
+        // L2
+        index -= self.pointers_per_block;
+        if index < self.pointers_per_block * self.pointers_per_block {
+            let l1_index = self
+                .read_index(inode.indirect_block_l2, index / self.pointers_per_block)
+                .await?;
+            return self
+                .read_index(l1_index, index % self.pointers_per_block)
+                .await;
         }
-    }
-}
-
-impl Deref for ExtendedSuperblock {
-    type Target = Superblock;
-
-    fn deref(&self) -> &Self::Target {
-        &self.base
-    }
-}
-
-impl DerefMut for ExtendedSuperblock {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.base
-    }
-}
-
-impl Inode {
-    pub fn blocks(&self, fs: &Ext2Fs) -> usize {
-        (self.size_lower as usize + fs.block_size - 1) / fs.block_size
+
+        // L3
+        index -= self.pointers_per_block * self.pointers_per_block;
+        if index < self.pointers_per_block * self.pointers_per_block * self.pointers_per_block {
+            let l2_pointer_index = index / self.pointers_per_block;
+            let l2_index = self
+                .read_index(
+                    inode.indirect_block_l3,
+                    l2_pointer_index / self.pointers_per_block,
+                )
+                .await?;
+            let l1_index = self
+                .read_index(l2_index, l2_pointer_index % self.pointers_per_block)
+                .await?;
+            return self
+                .read_index(l1_index, index % self.pointers_per_block)
+                .await;
+        }
+
+        log::error!("Invalid inode block index (over L3 indirect)");
+        Err(Error::InvalidFile)
     }
 }

kernel/libk/src/vfs/block/cache.rs

@@ -82,8 +82,8 @@ impl BlockCache {
                     .try_get_or_insert_with_async(address, || self.fetch_block(address))
                     .await?;
 
-                if evicted.is_some() {
-                    todo!()
+                if let Some((address, block)) = evicted {
+                    self.evict_block(address, block).await;
                 }
 
                 Ok(value)