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5d180d1f99
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED) Since all of these checks are done in release builds as well, let's rename them to VERIFY to prevent confusion, as everyone is used to assertions being compiled out in release. We can introduce a new ASSERT macro that is specifically for debug checks, but I'm doing this wholesale conversion first since we've accumulated thousands of these already, and it's not immediately obvious which ones are suitable for ASSERT.
324 lines
11 KiB
C++
324 lines
11 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/IntrusiveList.h>
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#include <Kernel/Debug.h>
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#include <Kernel/FileSystem/BlockBasedFileSystem.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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struct CacheEntry {
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IntrusiveListNode list_node;
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BlockBasedFS::BlockIndex block_index { 0 };
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u8* data { nullptr };
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bool has_data { false };
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};
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class DiskCache {
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public:
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explicit DiskCache(BlockBasedFS& fs)
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: m_fs(fs)
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, m_cached_block_data(KBuffer::create_with_size(m_entry_count * m_fs.block_size()))
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, m_entries(KBuffer::create_with_size(m_entry_count * sizeof(CacheEntry)))
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{
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for (size_t i = 0; i < m_entry_count; ++i) {
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entries()[i].data = m_cached_block_data.data() + i * m_fs.block_size();
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m_clean_list.append(entries()[i]);
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}
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}
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~DiskCache() { }
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bool is_dirty() const { return m_dirty; }
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void set_dirty(bool b) { m_dirty = b; }
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void mark_all_clean()
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{
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while (auto* entry = m_dirty_list.first())
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m_clean_list.prepend(*entry);
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m_dirty = false;
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}
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void mark_dirty(CacheEntry& entry)
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{
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m_dirty_list.prepend(entry);
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m_dirty = true;
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}
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void mark_clean(CacheEntry& entry)
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{
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m_clean_list.prepend(entry);
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}
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CacheEntry& get(BlockBasedFS::BlockIndex block_index) const
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{
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if (auto it = m_hash.find(block_index); it != m_hash.end()) {
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auto& entry = const_cast<CacheEntry&>(*it->value);
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VERIFY(entry.block_index == block_index);
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return entry;
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}
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if (m_clean_list.is_empty()) {
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// Not a single clean entry! Flush writes and try again.
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// NOTE: We want to make sure we only call FileBackedFS flush here,
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// not some FileBackedFS subclass flush!
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m_fs.flush_writes_impl();
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return get(block_index);
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}
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VERIFY(m_clean_list.last());
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auto& new_entry = *m_clean_list.last();
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m_clean_list.prepend(new_entry);
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m_hash.remove(new_entry.block_index);
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m_hash.set(block_index, &new_entry);
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new_entry.block_index = block_index;
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new_entry.has_data = false;
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return new_entry;
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}
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const CacheEntry* entries() const { return (const CacheEntry*)m_entries.data(); }
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CacheEntry* entries() { return (CacheEntry*)m_entries.data(); }
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template<typename Callback>
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void for_each_dirty_entry(Callback callback)
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{
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for (auto& entry : m_dirty_list)
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callback(entry);
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}
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private:
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BlockBasedFS& m_fs;
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size_t m_entry_count { 10000 };
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mutable HashMap<BlockBasedFS::BlockIndex, CacheEntry*> m_hash;
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mutable IntrusiveList<CacheEntry, &CacheEntry::list_node> m_clean_list;
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mutable IntrusiveList<CacheEntry, &CacheEntry::list_node> m_dirty_list;
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KBuffer m_cached_block_data;
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KBuffer m_entries;
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bool m_dirty { false };
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};
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BlockBasedFS::BlockBasedFS(FileDescription& file_description)
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: FileBackedFS(file_description)
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{
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VERIFY(file_description.file().is_seekable());
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}
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BlockBasedFS::~BlockBasedFS()
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{
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}
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KResult BlockBasedFS::write_block(BlockIndex index, const UserOrKernelBuffer& data, size_t count, size_t offset, bool allow_cache)
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{
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VERIFY(m_logical_block_size);
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VERIFY(offset + count <= block_size());
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dbgln_if(BBFS_DEBUG, "BlockBasedFileSystem::write_block {}, size={}", index, count);
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if (!allow_cache) {
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flush_specific_block_if_needed(index);
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u32 base_offset = index.value() * block_size() + offset;
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file_description().seek(base_offset, SEEK_SET);
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auto nwritten = file_description().write(data, count);
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if (nwritten.is_error())
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return nwritten.error();
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VERIFY(nwritten.value() == count);
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return KSuccess;
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}
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auto& entry = cache().get(index);
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if (count < block_size()) {
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// Fill the cache first.
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auto result = read_block(index, nullptr, block_size());
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if (result.is_error())
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return result;
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}
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if (!data.read(entry.data + offset, count))
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return EFAULT;
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cache().mark_dirty(entry);
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entry.has_data = true;
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return KSuccess;
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}
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bool BlockBasedFS::raw_read(BlockIndex index, UserOrKernelBuffer& buffer)
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{
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u32 base_offset = index.value() * m_logical_block_size;
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file_description().seek(base_offset, SEEK_SET);
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auto nread = file_description().read(buffer, m_logical_block_size);
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VERIFY(!nread.is_error());
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VERIFY(nread.value() == m_logical_block_size);
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return true;
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}
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bool BlockBasedFS::raw_write(BlockIndex index, const UserOrKernelBuffer& buffer)
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{
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size_t base_offset = index.value() * m_logical_block_size;
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file_description().seek(base_offset, SEEK_SET);
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auto nwritten = file_description().write(buffer, m_logical_block_size);
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VERIFY(!nwritten.is_error());
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VERIFY(nwritten.value() == m_logical_block_size);
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return true;
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}
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bool BlockBasedFS::raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer& buffer)
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{
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auto current = buffer;
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for (unsigned block = index.value(); block < (index.value() + count); block++) {
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if (!raw_read(BlockIndex { block }, current))
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return false;
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current = current.offset(logical_block_size());
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}
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return true;
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}
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bool BlockBasedFS::raw_write_blocks(BlockIndex index, size_t count, const UserOrKernelBuffer& buffer)
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{
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auto current = buffer;
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for (unsigned block = index.value(); block < (index.value() + count); block++) {
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if (!raw_write(block, current))
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return false;
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current = current.offset(logical_block_size());
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}
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return true;
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}
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KResult BlockBasedFS::write_blocks(BlockIndex index, unsigned count, const UserOrKernelBuffer& data, bool allow_cache)
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{
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VERIFY(m_logical_block_size);
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dbgln_if(BBFS_DEBUG, "BlockBasedFileSystem::write_blocks {}, count={}", index, count);
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for (unsigned i = 0; i < count; ++i) {
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auto result = write_block(BlockIndex { index.value() + i }, data.offset(i * block_size()), block_size(), 0, allow_cache);
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if (result.is_error())
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return result;
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}
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return KSuccess;
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}
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KResult BlockBasedFS::read_block(BlockIndex index, UserOrKernelBuffer* buffer, size_t count, size_t offset, bool allow_cache) const
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{
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VERIFY(m_logical_block_size);
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VERIFY(offset + count <= block_size());
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dbgln_if(BBFS_DEBUG, "BlockBasedFileSystem::read_block {}", index);
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if (!allow_cache) {
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const_cast<BlockBasedFS*>(this)->flush_specific_block_if_needed(index);
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size_t base_offset = index.value() * block_size() + offset;
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file_description().seek(base_offset, SEEK_SET);
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auto nread = file_description().read(*buffer, count);
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if (nread.is_error())
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return nread.error();
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VERIFY(nread.value() == count);
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return KSuccess;
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}
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auto& entry = cache().get(index);
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if (!entry.has_data) {
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size_t base_offset = index.value() * block_size();
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file_description().seek(base_offset, SEEK_SET);
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auto entry_data_buffer = UserOrKernelBuffer::for_kernel_buffer(entry.data);
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auto nread = file_description().read(entry_data_buffer, block_size());
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if (nread.is_error())
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return nread.error();
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VERIFY(nread.value() == block_size());
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entry.has_data = true;
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}
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if (buffer && !buffer->write(entry.data + offset, count))
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return EFAULT;
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return KSuccess;
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}
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KResult BlockBasedFS::read_blocks(BlockIndex index, unsigned count, UserOrKernelBuffer& buffer, bool allow_cache) const
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{
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VERIFY(m_logical_block_size);
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if (!count)
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return EINVAL;
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if (count == 1)
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return read_block(index, &buffer, block_size(), 0, allow_cache);
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auto out = buffer;
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for (unsigned i = 0; i < count; ++i) {
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auto result = read_block(BlockIndex { index.value() + i }, &out, block_size(), 0, allow_cache);
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if (result.is_error())
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return result;
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out = out.offset(block_size());
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}
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return KSuccess;
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}
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void BlockBasedFS::flush_specific_block_if_needed(BlockIndex index)
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{
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LOCKER(m_lock);
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if (!cache().is_dirty())
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return;
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Vector<CacheEntry*, 32> cleaned_entries;
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cache().for_each_dirty_entry([&](CacheEntry& entry) {
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if (entry.block_index != index) {
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size_t base_offset = entry.block_index.value() * block_size();
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file_description().seek(base_offset, SEEK_SET);
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// FIXME: Should this error path be surfaced somehow?
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auto entry_data_buffer = UserOrKernelBuffer::for_kernel_buffer(entry.data);
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[[maybe_unused]] auto rc = file_description().write(entry_data_buffer, block_size());
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cleaned_entries.append(&entry);
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}
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});
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// NOTE: We make a separate pass to mark entries clean since marking them clean
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// moves them out of the dirty list which would disturb the iteration above.
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for (auto* entry : cleaned_entries)
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cache().mark_clean(*entry);
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}
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void BlockBasedFS::flush_writes_impl()
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{
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LOCKER(m_lock);
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if (!cache().is_dirty())
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return;
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u32 count = 0;
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cache().for_each_dirty_entry([&](CacheEntry& entry) {
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u32 base_offset = entry.block_index.value() * block_size();
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file_description().seek(base_offset, SEEK_SET);
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// FIXME: Should this error path be surfaced somehow?
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auto entry_data_buffer = UserOrKernelBuffer::for_kernel_buffer(entry.data);
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[[maybe_unused]] auto rc = file_description().write(entry_data_buffer, block_size());
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++count;
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});
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cache().mark_all_clean();
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dbgln("{}: Flushed {} blocks to disk", class_name(), count);
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}
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void BlockBasedFS::flush_writes()
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{
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flush_writes_impl();
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}
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DiskCache& BlockBasedFS::cache() const
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{
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if (!m_cache)
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m_cache = make<DiskCache>(const_cast<BlockBasedFS&>(*this));
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return *m_cache;
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}
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}
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