Kernel: Use ErrorOr in BlockBased and Ext2 filesystem raw read and write

These functions used to return booleans which withheld useful
error information for callers. Internally they would suppress
and convert Error objects. We now log or propagate these errors
up the stack.

Kernel/FileSystem/BlockBasedFileSystem.cpp

@@ -169,44 +169,40 @@ ErrorOr<void> BlockBasedFileSystem::write_block(BlockIndex index, const UserOrKe
     });
 }
 
-bool BlockBasedFileSystem::raw_read(BlockIndex index, UserOrKernelBuffer& buffer)
+ErrorOr<void> BlockBasedFileSystem::raw_read(BlockIndex index, UserOrKernelBuffer& buffer)
 {
     auto base_offset = index.value() * m_logical_block_size;
-    auto nread = file_description().read(buffer, base_offset, m_logical_block_size);
+    auto nread = TRY(file_description().read(buffer, base_offset, m_logical_block_size));
-    VERIFY(!nread.is_error());
+    VERIFY(nread == m_logical_block_size);
-    VERIFY(nread.value() == m_logical_block_size);
+    return {};
-    return true;
 }
 
-bool BlockBasedFileSystem::raw_write(BlockIndex index, const UserOrKernelBuffer& buffer)
+ErrorOr<void> BlockBasedFileSystem::raw_write(BlockIndex index, const UserOrKernelBuffer& buffer)
 {
     auto base_offset = index.value() * m_logical_block_size;
-    auto nwritten = file_description().write(base_offset, buffer, m_logical_block_size);
+    auto nwritten = TRY(file_description().write(base_offset, buffer, m_logical_block_size));
-    VERIFY(!nwritten.is_error());
+    VERIFY(nwritten == m_logical_block_size);
-    VERIFY(nwritten.value() == m_logical_block_size);
+    return {};
-    return true;
 }
 
-bool BlockBasedFileSystem::raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer& buffer)
+ErrorOr<void> BlockBasedFileSystem::raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer& buffer)
 {
     auto current = buffer;
     for (auto block = index.value(); block < (index.value() + count); block++) {
-        if (!raw_read(BlockIndex { block }, current))
+        TRY(raw_read(BlockIndex { block }, current));
-            return false;
         current = current.offset(logical_block_size());
     }
-    return true;
+    return {};
 }
 
-bool BlockBasedFileSystem::raw_write_blocks(BlockIndex index, size_t count, const UserOrKernelBuffer& buffer)
+ErrorOr<void> BlockBasedFileSystem::raw_write_blocks(BlockIndex index, size_t count, const UserOrKernelBuffer& buffer)
 {
     auto current = buffer;
     for (auto block = index.value(); block < (index.value() + count); block++) {
-        if (!raw_write(block, current))
+        TRY(raw_write(block, current));
-            return false;
         current = current.offset(logical_block_size());
     }
-    return true;
+    return {};
 }
 
 ErrorOr<void> BlockBasedFileSystem::write_blocks(BlockIndex index, unsigned count, const UserOrKernelBuffer& data, bool allow_cache)

Kernel/FileSystem/BlockBasedFileSystem.h

@@ -29,11 +29,11 @@ protected:
     ErrorOr<void> read_block(BlockIndex, UserOrKernelBuffer*, size_t count, size_t offset = 0, bool allow_cache = true) const;
     ErrorOr<void> read_blocks(BlockIndex, unsigned count, UserOrKernelBuffer&, bool allow_cache = true) const;
 
-    bool raw_read(BlockIndex, UserOrKernelBuffer&);
+    ErrorOr<void> raw_read(BlockIndex, UserOrKernelBuffer&);
-    bool raw_write(BlockIndex, const UserOrKernelBuffer&);
+    ErrorOr<void> raw_write(BlockIndex, const UserOrKernelBuffer&);
 
-    bool raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer&);
+    ErrorOr<void> raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer&);
-    bool raw_write_blocks(BlockIndex index, size_t count, const UserOrKernelBuffer&);
+    ErrorOr<void> raw_write_blocks(BlockIndex index, size_t count, const UserOrKernelBuffer&);
 
     ErrorOr<void> write_block(BlockIndex, const UserOrKernelBuffer&, size_t count, size_t offset = 0, bool allow_cache = true);
     ErrorOr<void> write_blocks(BlockIndex, unsigned count, const UserOrKernelBuffer&, bool allow_cache = true);

Kernel/FileSystem/Ext2FileSystem.cpp

@@ -63,14 +63,12 @@ Ext2FS::~Ext2FS()
 {
 }
 
-bool Ext2FS::flush_super_block()
+ErrorOr<void> Ext2FS::flush_super_block()
 {
     MutexLocker locker(m_lock);
     VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
     auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
-    bool success = raw_write_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
+    return raw_write_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
-    VERIFY(success);
-    return true;
 }
 
 const ext2_group_desc& Ext2FS::group_descriptor(GroupIndex group_index) const
@@ -87,8 +85,7 @@ ErrorOr<void> Ext2FS::initialize()
 
     VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
     auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
-    bool success = raw_read_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
+    TRY(raw_read_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer));
-    VERIFY(success);
 
     auto const& super_block = this->super_block();
     if constexpr (EXT2_DEBUG) {
@@ -679,7 +676,12 @@ void Ext2FS::flush_writes()
     {
         MutexLocker locker(m_lock);
         if (m_super_block_dirty) {
-            flush_super_block();
+            auto result = flush_super_block();
+            if (result.is_error()) {
+                dbgln("Ext2FS[{}]::flush_writes(): Failed to write superblock: {}", fsid(), result.error());
+                // FIXME: We should handle this error.
+                VERIFY_NOT_REACHED();
+            }
             m_super_block_dirty = false;
         }
         if (m_block_group_descriptors_dirty) {

Kernel/FileSystem/Ext2FileSystem.h

@@ -122,7 +122,7 @@ private:
     ErrorOr<void> write_ext2_inode(InodeIndex, ext2_inode const&);
     bool find_block_containing_inode(InodeIndex, BlockIndex& block_index, unsigned& offset) const;
 
-    bool flush_super_block();
+    ErrorOr<void> flush_super_block();
 
     virtual StringView class_name() const override { return "Ext2FS"sv; }
     virtual Ext2FSInode& root_inode() override;

Kernel/FileSystem/ISO9660FileSystem.cpp

@@ -234,10 +234,10 @@ ErrorOr<void> ISO9660FS::parse_volume_set()
 
     auto current_block_index = first_data_area_block;
     while (true) {
-        bool result = raw_read(BlockIndex { current_block_index }, block_buffer);
+        auto result = raw_read(BlockIndex { current_block_index }, block_buffer);
-        if (!result) {
+        if (result.is_error()) {
-            dbgln_if(ISO9660_DEBUG, "Failed to read volume descriptor from ISO file");
+            dbgln_if(ISO9660_DEBUG, "Failed to read volume descriptor from ISO file: {}", result.error());
-            return EIO;
+            return result;
         }
 
         auto const* header = reinterpret_cast<ISO::VolumeDescriptorHeader const*>(block->data());
@@ -387,11 +387,7 @@ ErrorOr<NonnullRefPtr<ISO9660FS::DirectoryEntry>> ISO9660FS::directory_entry_for
 
     auto blocks = TRY(KBuffer::try_create_with_size(data_length, Memory::Region::Access::Read | Memory::Region::Access::Write, "ISO9660FS: Directory traversal buffer"));
     auto blocks_buffer = UserOrKernelBuffer::for_kernel_buffer(blocks->data());
-    auto did_read = raw_read_blocks(BlockBasedFileSystem::BlockIndex { extent_location }, data_length / logical_block_size(), blocks_buffer);
+    TRY(raw_read_blocks(BlockBasedFileSystem::BlockIndex { extent_location }, data_length / logical_block_size(), blocks_buffer));
-    if (!did_read) {
-        return EIO;
-    }
-
     auto entry = TRY(DirectoryEntry::try_create(extent_location, data_length, move(blocks)));
     m_directory_entry_cache.set(key, entry);
 
@@ -428,10 +424,7 @@ ErrorOr<size_t> ISO9660Inode::read_bytes(off_t offset, size_t size, UserOrKernel
         auto buffer_offset = buffer.offset(nread);
         dbgln_if(ISO9660_VERY_DEBUG, "ISO9660Inode::read_bytes: Reading {} bytes into buffer offset {}/{}, logical block index: {}", bytes_to_read, nread, total_bytes, current_block_index.value());
 
-        if (bool result = const_cast<ISO9660FS&>(fs()).raw_read(current_block_index, block_buffer); !result) {
+        TRY(const_cast<ISO9660FS&>(fs()).raw_read(current_block_index, block_buffer));
-            return EIO;
-        }
-
         TRY(buffer_offset.write(block->data() + initial_offset, bytes_to_read));
 
         nread += bytes_to_read;