Merge "snapuserd: Read partition blocks to memory" (e19f7be1) · Commits · e / os / android_system_core

fs_mgr/libdm/dm.cpp

+56 −0

Original line number	Diff line number	Diff line
		@@ -651,5 +651,61 @@ bool DeviceMapper::TargetInfo::IsOverflowSnapshot() const {
		return spec.target_type == "snapshot"s && data == "Overflow"s;
		}

		// Find directories in format of "/sys/block/dm-X".
		static int DmNameFilter(const dirent* de) {
		if (android::base::StartsWith(de->d_name, "dm-")) {
		return 1;
		}
		return 0;
		}

		std::map<std::string, std::string> DeviceMapper::FindDmPartitions() {
		static constexpr auto DM_PATH_PREFIX = "/sys/block/";
		dirent** namelist;
		int n = scandir(DM_PATH_PREFIX, &namelist, DmNameFilter, alphasort);
		if (n == -1) {
		PLOG(ERROR) << "Failed to scan dir " << DM_PATH_PREFIX;
		return {};
		}
		if (n == 0) {
		LOG(ERROR) << "No dm block device found.";
		free(namelist);
		return {};
		}

		static constexpr auto DM_PATH_SUFFIX = "/dm/name";
		static constexpr auto DEV_PATH = "/dev/block/";
		std::map<std::string, std::string> dm_block_devices;
		while (n--) {
		std::string path = DM_PATH_PREFIX + std::string(namelist[n]->d_name) + DM_PATH_SUFFIX;
		std::string content;
		if (!android::base::ReadFileToString(path, &content)) {
		PLOG(WARNING) << "Failed to read " << path;
		} else {
		std::string dm_block_name = android::base::Trim(content);
		// AVB is using 'vroot' for the root block device but we're expecting 'system'.
		if (dm_block_name == "vroot") {
		dm_block_name = "system";
		} else if (android::base::EndsWith(dm_block_name, "-verity")) {
		auto npos = dm_block_name.rfind("-verity");
		dm_block_name = dm_block_name.substr(0, npos);
		} else if (!android::base::GetProperty("ro.boot.avb_version", "").empty()) {
		// Verified Boot 1.0 doesn't add a -verity suffix. On AVB 2 devices,
		// if DAP is enabled, then a -verity suffix must be used to
		// differentiate between dm-linear and dm-verity devices. If we get
		// here, we're AVB 2 and looking at a non-verity partition.
		free(namelist[n]);
		continue;
		}

		dm_block_devices.emplace(dm_block_name, DEV_PATH + std::string(namelist[n]->d_name));
		}
		free(namelist[n]);
		}
		free(namelist);

		return dm_block_devices;
		}

		} // namespace dm
		} // namespace android

fs_mgr/libdm/include/libdm/dm.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		#ifndef _LIBDM_DM_H_
		#define _LIBDM_DM_H_

		#include <dirent.h>
		#include <fcntl.h>
		#include <linux/dm-ioctl.h>
		#include <linux/kdev_t.h>
		@@ -26,6 +27,7 @@
		#include <unistd.h>

		#include <chrono>
		#include <map>
		#include <memory>
		#include <optional>
		#include <string>
		@@ -255,6 +257,12 @@ class DeviceMapper final {
		// * A failure occurred.
		std::optional<std::string> GetParentBlockDeviceByPath(const std::string& path);

		// Iterate the content over "/sys/block/dm-x/dm/name" and find
		// all the dm-wrapped block devices.
		//
		// Returns mapping <partition-name, /dev/block/dm-x>
		std::map<std::string, std::string> FindDmPartitions();

		private:
		// Maximum possible device mapper targets registered in the kernel.
		// This is only used to read the list of targets from kernel so we allocate

fs_mgr/libsnapshot/snapuserd/Android.bp

+2 −0

Original line number	Diff line number	Diff line
		@@ -78,6 +78,7 @@ cc_defaults {
		"liblog",
		"libsnapshot_cow",
		"libz",
		"libext4_utils",
		],
		}

		@@ -121,6 +122,7 @@ cc_test {
		"libz",
		"libfs_mgr",
		"libdm",
		"libext4_utils",
		],
		header_libs: [
		"libstorage_literals_headers",

fs_mgr/libsnapshot/snapuserd/include/snapuserd/snapuserd_kernel.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -47,8 +47,6 @@ typedef sector_t chunk_t;
		static constexpr uint32_t CHUNK_SIZE = 8;
		static constexpr uint32_t CHUNK_SHIFT = (__builtin_ffs(CHUNK_SIZE) - 1);

		#define DIV_ROUND_UP(n, d) (((n) + (d)-1) / (d))

		// This structure represents the kernel COW header.
		// All the below fields should be in Little Endian format.
		struct disk_header {

fs_mgr/libsnapshot/snapuserd/snapuserd.cpp

+113 −0

Original line number	Diff line number	Diff line
		@@ -16,10 +16,22 @@

		#include "snapuserd.h"

		#include <dirent.h>
		#include <fcntl.h>
		#include <linux/fs.h>
		#include <unistd.h>
		#include <algorithm>

		#include <csignal>
		#include <optional>
		#include <set>

		#include <android-base/file.h>
		#include <android-base/logging.h>
		#include <android-base/parseint.h>
		#include <android-base/properties.h>
		#include <android-base/strings.h>
		#include <android-base/unique_fd.h>
		#include <snapuserd/snapuserd_client.h>

		namespace android {
		@@ -678,6 +690,74 @@ bool Snapuserd::InitCowDevice() {
		return ReadMetadata();
		}

		void Snapuserd::ReadBlocksToCache(const std::string& dm_block_device,
		const std::string partition_name, off_t offset, size_t size) {
		android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(dm_block_device.c_str(), O_RDONLY)));
		if (fd.get() == -1) {
		SNAP_PLOG(ERROR) << "Error reading " << dm_block_device
		<< " partition-name: " << partition_name;
		return;
		}

		size_t remain = size;
		off_t file_offset = offset;
		// We pick 4M I/O size based on the fact that the current
		// update_verifier has a similar I/O size.
		size_t read_sz = 1024 * BLOCK_SZ;
		std::vector<uint8_t> buf(read_sz);

		while (remain > 0) {
		size_t to_read = std::min(remain, read_sz);

		if (!android::base::ReadFullyAtOffset(fd.get(), buf.data(), to_read, file_offset)) {
		SNAP_PLOG(ERROR) << "Failed to read block from block device: " << dm_block_device
		<< " at offset: " << file_offset
		<< " partition-name: " << partition_name << " total-size: " << size
		<< " remain_size: " << remain;
		return;
		}

		file_offset += to_read;
		remain -= to_read;
		}

		SNAP_LOG(INFO) << "Finished reading block-device: " << dm_block_device
		<< " partition: " << partition_name << " size: " << size
		<< " offset: " << offset;
		}

		void Snapuserd::ReadBlocks(const std::string partition_name, const std::string& dm_block_device) {
		SNAP_LOG(DEBUG) << "Reading partition: " << partition_name
		<< " Block-Device: " << dm_block_device;

		uint64_t dev_sz = 0;

		unique_fd fd(TEMP_FAILURE_RETRY(open(dm_block_device.c_str(), O_RDONLY \| O_CLOEXEC)));
		if (fd < 0) {
		SNAP_LOG(ERROR) << "Cannot open block device";
		return;
		}

		dev_sz = get_block_device_size(fd.get());
		if (!dev_sz) {
		SNAP_PLOG(ERROR) << "Could not determine block device size: " << dm_block_device;
		return;
		}

		int num_threads = 2;
		size_t num_blocks = dev_sz >> BLOCK_SHIFT;
		size_t num_blocks_per_thread = num_blocks / num_threads;
		size_t read_sz_per_thread = num_blocks_per_thread << BLOCK_SHIFT;
		off_t offset = 0;

		for (int i = 0; i < num_threads; i++) {
		std::async(std::launch::async, &Snapuserd::ReadBlocksToCache, this, dm_block_device,
		partition_name, offset, read_sz_per_thread);

		offset += read_sz_per_thread;
		}
		}

		/*
		* Entry point to launch threads
		*/
		@@ -706,6 +786,39 @@ bool Snapuserd::Start() {
		std::async(std::launch::async, &WorkerThread::RunThread, worker_threads_[i].get()));
		}

		bool second_stage_init = true;

		// We don't want to read the blocks during first stage init.
		if (android::base::EndsWith(misc_name_, "-init") \|\| is_socket_present_) {
		second_stage_init = false;
		}

		if (second_stage_init) {
		SNAP_LOG(INFO) << "Reading blocks to cache....";
		auto& dm = DeviceMapper::Instance();
		auto dm_block_devices = dm.FindDmPartitions();
		if (dm_block_devices.empty()) {
		SNAP_LOG(ERROR) << "No dm-enabled block device is found.";
		} else {
		auto parts = android::base::Split(misc_name_, "-");
		std::string partition_name = parts[0];

		const char* suffix_b = "_b";
		const char* suffix_a = "_a";

		partition_name.erase(partition_name.find_last_not_of(suffix_b) + 1);
		partition_name.erase(partition_name.find_last_not_of(suffix_a) + 1);

		if (dm_block_devices.find(partition_name) == dm_block_devices.end()) {
		SNAP_LOG(ERROR) << "Failed to find dm block device for " << partition_name;
		} else {
		ReadBlocks(partition_name, dm_block_devices.at(partition_name));
		}
		}
		} else {
		SNAP_LOG(INFO) << "Not reading block device into cache";
		}

		bool ret = true;
		for (auto& t : threads) {
		ret = t.get() && ret;