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872f2a3b90
These changes are arbitrarily divided into multiple commits to make it easier to find potentially introduced bugs with git bisect.Everything:
334 lines
11 KiB
C++
334 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/FileSystem/BlockBasedFileSystem.h>
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#include <Kernel/Process.h>
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//#define BBFS_DEBUG
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namespace Kernel {
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struct CacheEntry {
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IntrusiveListNode list_node;
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u32 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(u32 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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ASSERT(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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ASSERT(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_clean_entry(Callback callback)
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{
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for (auto& entry : m_clean_list)
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callback(entry);
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}
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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<u32, 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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ASSERT(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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int BlockBasedFS::write_block(unsigned index, const UserOrKernelBuffer& data, size_t count, size_t offset, bool allow_cache)
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{
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ASSERT(m_logical_block_size);
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ASSERT(offset + count <= block_size());
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#ifdef BBFS_DEBUG
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klog() << "BlockBasedFileSystem::write_block " << index << ", size=" << count;
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#endif
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if (!allow_cache) {
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flush_specific_block_if_needed(index);
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u32 base_offset = static_cast<u32>(index) * static_cast<u32>(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 -EIO; // TODO: Return error code as-is, could be -EFAULT!
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ASSERT(nwritten.value() == count);
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return 0;
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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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read_block(index, nullptr, block_size());
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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 0;
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}
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bool BlockBasedFS::raw_read(unsigned index, UserOrKernelBuffer& buffer)
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{
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u32 base_offset = static_cast<u32>(index) * static_cast<u32>(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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ASSERT(!nread.is_error());
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ASSERT(nread.value() == m_logical_block_size);
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return true;
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}
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bool BlockBasedFS::raw_write(unsigned index, const UserOrKernelBuffer& buffer)
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{
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u32 base_offset = static_cast<u32>(index) * static_cast<u32>(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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ASSERT(!nwritten.is_error());
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ASSERT(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(unsigned 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; block < (index + count); block++) {
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if (!raw_read(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(unsigned 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; block < (index + 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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int BlockBasedFS::write_blocks(unsigned index, unsigned count, const UserOrKernelBuffer& data, bool allow_cache)
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{
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ASSERT(m_logical_block_size);
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#ifdef BBFS_DEBUG
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klog() << "BlockBasedFileSystem::write_blocks " << index << " x" << count;
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#endif
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for (unsigned i = 0; i < count; ++i)
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write_block(index + i, data.offset(i * block_size()), block_size(), 0, allow_cache);
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return 0;
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}
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int BlockBasedFS::read_block(unsigned index, UserOrKernelBuffer* buffer, size_t count, size_t offset, bool allow_cache) const
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{
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ASSERT(m_logical_block_size);
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ASSERT(offset + count <= block_size());
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#ifdef BBFS_DEBUG
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klog() << "BlockBasedFileSystem::read_block " << index;
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#endif
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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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u32 base_offset = static_cast<u32>(index) * static_cast<u32>(block_size()) + static_cast<u32>(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 -EIO;
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ASSERT(nread.value() == count);
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return 0;
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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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u32 base_offset = static_cast<u32>(index) * static_cast<u32>(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 -EIO;
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ASSERT(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 0;
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}
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int BlockBasedFS::read_blocks(unsigned index, unsigned count, UserOrKernelBuffer& buffer, bool allow_cache) const
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{
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ASSERT(m_logical_block_size);
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if (!count)
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return false;
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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 err = read_block(index + i, &out, block_size(), 0, allow_cache);
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if (err < 0)
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return err;
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out = out.offset(block_size());
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}
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return 0;
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}
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void BlockBasedFS::flush_specific_block_if_needed(unsigned 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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u32 base_offset = static_cast<u32>(entry.block_index) * static_cast<u32>(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 = static_cast<u32>(entry.block_index) * static_cast<u32>(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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