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Kernel: Introduce a new partitioning subsystem
The partitioning code was very outdated, and required a full refactor. The new subsystem removes duplicated code and uses more AK containers. The most important change is that all implementations of the PartitionTable class conform to one interface, which made it possible to remove unnecessary code in the EBRPartitionTable class. Finding partitions is now done in the StorageManagement singleton, instead of doing so in init.cpp. Also, now we don't try to find partitions on demand - the kernel will try to detect if a StorageDevice is partitioned, and if so, will check what is the partition table, which could be MBR, GUID or EBR. Then, it will create DiskPartitionMetadata object for each partition that is available in the partition table. This object will be used by the partition enumeration code to create a DiskPartition with the correct minor number.
This commit is contained in:
Liav A
Andreas Kling
parent
bc18712adf
commit
72b1998f0d
20 changed files with 639 additions and 561 deletions
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@ -33,176 +33,69 @@
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namespace Kernel {
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EBRPartitionTable::EBRPartitionTable(NonnullRefPtr<BlockDevice> device)
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: m_device(move(device))
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Result<NonnullOwnPtr<EBRPartitionTable>, PartitionTable::Error> EBRPartitionTable::try_to_initialize(const StorageDevice& device)
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{
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auto table = make<EBRPartitionTable>(device);
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if (table->is_protective_mbr())
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return { PartitionTable::Error::MBRProtective };
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if (!table->is_valid())
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return { PartitionTable::Error::Invalid };
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return table;
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}
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void EBRPartitionTable::search_extended_partition(const StorageDevice& device, MBRPartitionTable& checked_ebr, u64 current_block_offset, size_t limit)
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{
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if (limit == 0)
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return;
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// EBRs should not carry more than 2 partitions (because they need to form a linked list)
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ASSERT(checked_ebr.partitions_count() <= 2);
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auto checked_logical_partition = checked_ebr.partition(0);
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// If we are pointed to an invalid logical partition, something is seriously wrong.
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ASSERT(checked_logical_partition.has_value());
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m_partitions.append(checked_logical_partition.value().offset(current_block_offset));
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if (!checked_ebr.contains_ebr())
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return;
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current_block_offset += checked_ebr.partition(1).value().start_block();
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auto next_ebr = MBRPartitionTable::try_to_initialize(device, current_block_offset);
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if (!next_ebr)
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return;
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search_extended_partition(device, *next_ebr, current_block_offset, (limit - 1));
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}
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EBRPartitionTable::EBRPartitionTable(const StorageDevice& device)
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: MBRPartitionTable(device)
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{
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if (!is_header_valid())
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return;
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m_valid = true;
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ASSERT(partitions_count() == 0);
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auto& header = this->header();
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for (size_t index = 0; index < 4; index++) {
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auto& entry = header.entry[index];
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// Start enumerating all logical partitions
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if (entry.type == 0xf) {
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auto checked_ebr = MBRPartitionTable::try_to_initialize(device, entry.offset);
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if (!checked_ebr)
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continue;
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// It's quite unlikely to see that amount of partitions, so stop at 128 partitions.
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search_extended_partition(device, *checked_ebr, entry.offset, 128);
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continue;
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}
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if (entry.offset == 0x00) {
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continue;
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}
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auto partition_type = ByteBuffer::create_zeroed(sizeof(u8));
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partition_type.data()[0] = entry.type;
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m_partitions.append(DiskPartitionMetadata({ entry.offset, (entry.offset + entry.length), partition_type }));
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}
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}
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EBRPartitionTable::~EBRPartitionTable()
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{
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}
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const MBRPartitionHeader& EBRPartitionTable::header() const
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{
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return *reinterpret_cast<const MBRPartitionHeader*>(m_cached_mbr_header);
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}
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const EBRPartitionExtension& EBRPartitionTable::ebr_extension() const
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{
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return *reinterpret_cast<const EBRPartitionExtension*>(m_cached_ebr_header);
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}
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int EBRPartitionTable::index_of_ebr_container() const
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{
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for (int i = 0; i < 4; i++) {
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if (header().entry[i].type == EBR_CHS_CONTAINER || header().entry[i].type == EBR_LBA_CONTAINER)
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return i;
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}
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ASSERT_NOT_REACHED();
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}
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bool EBRPartitionTable::initialize()
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{
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auto mbr_header_request = m_device->make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read,
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0, 1, UserOrKernelBuffer::for_kernel_buffer(m_cached_mbr_header), sizeof(m_cached_mbr_header));
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auto mbr_header_buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_mbr_header);
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if (!m_device->read_block(0, mbr_header_buffer)) {
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return false;
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}
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auto& header = this->header();
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m_ebr_container_id = index_of_ebr_container() + 1;
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::initialize: MBR_signature=0x" << String::format("%x", header.mbr_signature);
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#endif
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if (header.mbr_signature != MBR_SIGNATURE) {
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klog() << "EBRPartitionTable::initialize: bad MBR signature 0x" << String::format("%x", header.mbr_signature);
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return false;
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}
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auto& ebr_entry = header.entry[m_ebr_container_id - 1];
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auto ebr_header_buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_ebr_header);
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if (!m_device->read_block(ebr_entry.offset, ebr_header_buffer)) {
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return false;
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}
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size_t index = 1;
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while (index < 128) { // Unlikely to encounter a disk with 128 partitions in this configuration...
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if (ebr_extension().next_chained_ebr_extension.offset == 0 && ebr_extension().next_chained_ebr_extension.type == 0) {
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break;
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}
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index++;
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if (!m_device->read_block(ebr_extension().next_chained_ebr_extension.offset, ebr_header_buffer)) {
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return false;
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}
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}
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m_ebr_chained_extensions_count = index;
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klog() << "EBRPartitionTable::initialize: Extended partitions count - " << m_ebr_chained_extensions_count;
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return true;
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}
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RefPtr<DiskPartition> EBRPartitionTable::get_non_extended_partition(unsigned index)
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{
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auto& header = this->header();
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auto& entry = header.entry[index - 1];
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: status=0x" << String::format("%x", entry.status) << " offset=0x" << String::format("%x", entry.offset);
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#endif
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if (entry.offset == 0x00) {
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: missing partition requested index=" << index;
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#endif
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return nullptr;
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}
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: found partition index=" << index << " type=" << String::format("%x", entry.type);
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#endif
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return DiskPartition::create(m_device, entry.offset, (entry.offset + entry.length));
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}
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RefPtr<DiskPartition> EBRPartitionTable::get_extended_partition(unsigned index)
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{
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unsigned relative_index = index - m_ebr_container_id;
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auto& header = this->header();
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: relative index " << relative_index;
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#endif
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auto& ebr_entry = header.entry[m_ebr_container_id - 1];
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: Extended partition, offset 0x" << String::format("%x", ebr_entry.offset) << ", type " << String::format("%x", ebr_entry.type);
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#endif
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auto ebr_header_buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_ebr_header);
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if (!m_device->read_block(ebr_entry.offset, ebr_header_buffer)) {
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return nullptr;
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}
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size_t i = 0;
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while (i < relative_index) {
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: logical partition, relative offset 0x" << String::format("%x", ebr_extension().entry.offset) << ", type " << String::format("%x", ebr_extension().entry.type);
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klog() << "EBRPartitionTable::partition: next logical partition, relative offset 0x" << String::format("%x", ebr_extension().next_chained_ebr_extension.offset) << ", type " << String::format("%x", ebr_extension().next_chained_ebr_extension.type);
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#endif
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if (ebr_extension().next_chained_ebr_extension.offset == 0 && ebr_extension().next_chained_ebr_extension.type == 0) {
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break;
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}
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i++;
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if (!m_device->read_block(ebr_extension().next_chained_ebr_extension.offset, ebr_header_buffer)) {
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return nullptr;
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}
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}
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: status=" << String::format("%x", ebr_extension().entry.status) << " offset=" << String::format("%x", ebr_extension().entry.offset + ebr_entry.offset);
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#endif
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if (ebr_extension().entry.offset == 0x00) {
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: missing partition requested index=" << index;
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#endif
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return nullptr;
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}
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#ifdef EBR_DEBUG
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klog() << "EBRPartitionTable::partition: found partition index=" << index << " type=" << String::format("%x", ebr_extension().entry.type);
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#endif
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return DiskPartition::create(m_device, ebr_extension().entry.offset + ebr_entry.offset, (ebr_extension().entry.offset + ebr_entry.offset + ebr_extension().entry.length));
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}
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bool EBRPartitionTable::index_is_extended_partition(unsigned index) const
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{
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return !(m_ebr_container_id > index || index > (m_ebr_container_id + m_ebr_chained_extensions_count));
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}
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RefPtr<DiskPartition> EBRPartitionTable::partition(unsigned index)
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{
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ASSERT(index >= 1 && index <= m_ebr_chained_extensions_count + 4);
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auto& header = this->header();
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if (header.mbr_signature != MBR_SIGNATURE) {
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klog() << "EBRPartitionTable::initialize: bad MBR signature - not initialized? 0x" << String::format("%x", header.mbr_signature);
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return nullptr;
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}
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if (index_is_extended_partition(index))
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return get_extended_partition(index);
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if (index > 4)
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return get_non_extended_partition(index - m_ebr_chained_extensions_count);
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return get_non_extended_partition(index);
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}
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}
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