ext2: properly handle max file size

kernel/driver/fs/ext2/src/inode/mod.rs

@@ -229,6 +229,7 @@ impl Inode {
             self.size_upper = (size >> 32) as u32;
             self.size_lower = size as u32;
         } else {
+            // Unreachable: size is checked in resize()
             if size > u32::MAX as u64 {
                 todo!("File too large")
             }
@@ -242,8 +243,10 @@ impl Inode {
         if size == self.size(fs) {
             return Ok(false);
         }
-
+        if size > fs.max_file_size {
-        // TODO check max inode size
+            // TODO FileTooBig or something
+            return Err(Error::InvalidArgument);
+        }
 
         let is_symlink = self
             .mode
@@ -256,11 +259,12 @@ impl Inode {
         } else {
             size.div_ceil(fs.block_size as u64)
         };
-        // TODO check size_upper as well?
+
-        let old_blocks = if is_symlink && self.size_lower < 60 {
+        let old_size = self.size(fs);
+        let old_blocks = if is_symlink && old_size < 60 {
             0
         } else {
-            self.size(fs).div_ceil(fs.block_size as u64)
+            old_size.div_ceil(fs.block_size as u64)
         };
 
         if new_blocks as usize
@@ -268,7 +272,7 @@ impl Inode {
                 + fs.pointers_per_block
                 + fs.pointers_per_block * fs.pointers_per_block
         {
-            log::warn!("ext2: only L0/L1 are supported");
+            log::warn!("ext2: only L0/L1/L2 are supported");
             return Err(Error::InvalidArgument);
         }
 

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

@@ -9,7 +9,7 @@ use core::mem;
 use alloc::{boxed::Box, sync::Arc};
 use async_trait::async_trait;
 use bytemuck::Zeroable;
-use data::{FsReadonlyFeatures, FsRequiredFeatures};
+use data::{FsReadonlyFeatures, FsRequiredFeatures, DIRECT_BLOCK_COUNT};
 use dir::DirectoryNode;
 use file::RegularNode;
 use inode::{InodeAccess, InodeCache};
@@ -56,6 +56,8 @@ pub struct Ext2Fs {
     inodes_per_block: usize,
     pointers_per_block: usize,
 
+    max_file_size: u64,
+
     required_features: FsRequiredFeatures,
     write_features: FsReadonlyFeatures,
 
@@ -259,17 +261,32 @@ impl Ext2Fs {
             }
         };
 
+        let pointers_per_block = block_size / size_of::<u32>();
+        let max_inode_blocks = (DIRECT_BLOCK_COUNT
+            + pointers_per_block
+            + pointers_per_block * pointers_per_block
+            + pointers_per_block * pointers_per_block * pointers_per_block)
+            as u64;
+        let max_file_size = max_inode_blocks.saturating_mul(block_size as u64);
+        let max_file_size = if write_features.contains(FsReadonlyFeatures::FILE_SIZE_64_BIT) {
+            max_file_size
+        } else {
+            max_file_size.min(u32::MAX as u64)
+        };
+
         Ok(Self {
             block_size,
             inode_size: superblock.inode_size(),
             inodes_per_block: block_size / superblock.inode_size(),
-            pointers_per_block: block_size / size_of::<u32>(),
+            pointers_per_block,
 
             total_inodes,
             total_blocks,
             block_group_inode_count,
             block_group_block_count,
 
+            max_file_size,
+
             mapper,
             inode_cache: OneTimeInit::new(),
 
@@ -393,26 +410,6 @@ impl Ext2Fs {
         self.inode_cache.get().flush().await
     }
 
-    // pub async fn flush_superblock(&self) -> Result<(), Error> {
-    //     let state = self.state.read();
-    //     if state.dirty {
-    //         log::info!("Flushing superblock");
-    //         log::info!(
-    //             "inodes {} blocks {}",
-    //             state.superblock.total_unallocated_inodes,
-    //             state.superblock.total_unallocated_blocks
-    //         );
-    //         self.mapper
-    //             .device()
-    //             .write_exact(
-    //                 data::SUPERBLOCK_OFFSET,
-    //                 bytemuck::bytes_of(&state.superblock),
-    //             )
-    //             .await?;
-    //     }
-    //     Ok(())
-    // }
-
     async fn read_index(&self, block_index: u32, index: usize) -> Result<u32, Error> {
         self.with_block(block_index, |block| {
             let indirect: &[u32] = unsafe {