fs_mgr/fs_mgr_dm_linear.cpp

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "fs_mgr_dm_linear.h"

#include <inttypes.h>
#include <linux/dm-ioctl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <unistd.h>

#include <sstream>

#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <liblp/reader.h>

#include "fs_mgr_priv.h"

namespace android {
namespace fs_mgr {

using DeviceMapper = android::dm::DeviceMapper;
using DmTable = android::dm::DmTable;
using DmTarget = android::dm::DmTarget;
using DmTargetZero = android::dm::DmTargetZero;
using DmTargetLinear = android::dm::DmTargetLinear;

static bool GetPhysicalPartitionDevicePath(const LpMetadata& metadata,
                                           const LpMetadataBlockDevice& block_device,
                                           const std::string& super_device,
                                           std::string* result) {
    // Note: device-mapper will not accept symlinks, so we must use realpath
    // here.
    std::string name = GetBlockDevicePartitionName(block_device);
    std::string path = "/dev/block/by-name/" + name;
    // If the super device is the source of this block device's metadata,
    // make sure we use the correct super device (and not just "super",
    // which might not exist.)
    if (GetMetadataSuperBlockDevice(metadata) == &block_device) {
        path = super_device;
    }
    if (!android::base::Realpath(path, result)) {
        PERROR << "realpath: " << path;
        return false;
    }
    return true;
}

static bool CreateDmTable(const LpMetadata& metadata, const LpMetadataPartition& partition,
                          const std::string& super_device, DmTable* table) {
    uint64_t sector = 0;
    for (size_t i = 0; i < partition.num_extents; i++) {
        const auto& extent = metadata.extents[partition.first_extent_index + i];
        std::unique_ptr<DmTarget> target;
        switch (extent.target_type) {
            case LP_TARGET_TYPE_ZERO:
                target = std::make_unique<DmTargetZero>(sector, extent.num_sectors);
                break;
            case LP_TARGET_TYPE_LINEAR: {
                const auto& block_device = metadata.block_devices[extent.target_source];
                std::string path;
                if (!GetPhysicalPartitionDevicePath(metadata, block_device, super_device, &path)) {
                    LOG(ERROR) << "Unable to complete device-mapper table, unknown block device";
                    return false;
                }
                target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, path,
                                                          extent.target_data);
                break;
            }
            default:
                LOG(ERROR) << "Unknown target type in metadata: " << extent.target_type;
                return false;
        }
        if (!table->AddTarget(std::move(target))) {
            return false;
        }
        sector += extent.num_sectors;
    }
    if (partition.attributes & LP_PARTITION_ATTR_READONLY) {
        table->set_readonly(true);
    }
    return true;
}

static bool CreateLogicalPartition(const LpMetadata& metadata, const LpMetadataPartition& partition,
                                   bool force_writable, const std::chrono::milliseconds& timeout_ms,
                                   const std::string& super_device, std::string* path) {
    DeviceMapper& dm = DeviceMapper::Instance();

    DmTable table;
    if (!CreateDmTable(metadata, partition, super_device, &table)) {
        return false;
    }
    if (force_writable) {
        table.set_readonly(false);
    }
    std::string name = GetPartitionName(partition);
    if (!dm.CreateDevice(name, table)) {
        return false;
    }
    if (!dm.GetDmDevicePathByName(name, path)) {
        return false;
    }
    if (timeout_ms > std::chrono::milliseconds::zero()) {
        if (!fs_mgr_wait_for_file(*path, timeout_ms, FileWaitMode::Exists)) {
            DestroyLogicalPartition(name, {});
            LERROR << "Timed out waiting for device path: " << *path;
            return false;
        }
    }
    LINFO << "Created logical partition " << name << " on device " << *path;
    return true;
}

bool CreateLogicalPartitions(const std::string& block_device) {
    uint32_t slot = SlotNumberForSlotSuffix(fs_mgr_get_slot_suffix());
    auto metadata = ReadMetadata(block_device.c_str(), slot);
    if (!metadata) {
        LOG(ERROR) << "Could not read partition table.";
        return true;
    }
    return CreateLogicalPartitions(*metadata.get(), block_device);
}

std::unique_ptr<LpMetadata> ReadCurrentMetadata(const std::string& block_device) {
    uint32_t slot = SlotNumberForSlotSuffix(fs_mgr_get_slot_suffix());
    return ReadMetadata(block_device.c_str(), slot);
}

bool CreateLogicalPartitions(const LpMetadata& metadata, const std::string& super_device) {
    for (const auto& partition : metadata.partitions) {
        if (!partition.num_extents) {
            LINFO << "Skipping zero-length logical partition: " << GetPartitionName(partition);
            continue;
        }
        std::string path;
        if (!CreateLogicalPartition(metadata, partition, false, {}, super_device, &path)) {
            LERROR << "Could not create logical partition: " << GetPartitionName(partition);
            return false;
        }
    }
    return true;
}

bool CreateLogicalPartition(const std::string& block_device, const LpMetadata& metadata,
                            const std::string& partition_name, bool force_writable,
                            const std::chrono::milliseconds& timeout_ms, std::string* path) {
    for (const auto& partition : metadata.partitions) {
        if (GetPartitionName(partition) == partition_name) {
            return CreateLogicalPartition(metadata, partition, force_writable, timeout_ms,
                                          block_device, path);
        }
    }
    LERROR << "Could not find any partition with name: " << partition_name;
    return false;
}

bool CreateLogicalPartition(const std::string& block_device, uint32_t metadata_slot,
                            const std::string& partition_name, bool force_writable,
                            const std::chrono::milliseconds& timeout_ms, std::string* path) {
    auto metadata = ReadMetadata(block_device.c_str(), metadata_slot);
    if (!metadata) {
        LOG(ERROR) << "Could not read partition table.";
        return true;
    }
    return CreateLogicalPartition(block_device, *metadata.get(), partition_name, force_writable,
                                  timeout_ms, path);
}

bool DestroyLogicalPartition(const std::string& name, const std::chrono::milliseconds& timeout_ms) {
    DeviceMapper& dm = DeviceMapper::Instance();
    std::string path;
    if (timeout_ms > std::chrono::milliseconds::zero()) {
        dm.GetDmDevicePathByName(name, &path);
    }
    if (!dm.DeleteDevice(name)) {
        return false;
    }
    if (!path.empty() && !fs_mgr_wait_for_file(path, timeout_ms, FileWaitMode::DoesNotExist)) {
        LERROR << "Timed out waiting for device path to unlink: " << path;
        return false;
    }
    LINFO << "Unmapped logical partition " << name;
    return true;
}

}  // namespace fs_mgr
}  // namespace android