Reduce the queue depth of loop devices used by the zram driver am: 1a9cad816d (d5a663fd) · Commits · e / os / android_system_core

fs_mgr/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -63,6 +63,7 @@ cc_defaults {
		"-D_FILE_OFFSET_BITS=64",
		],
		srcs: [
		"blockdev.cpp",
		"file_wait.cpp",
		"fs_mgr.cpp",
		"fs_mgr_format.cpp",

fs_mgr/blockdev.cpp

0 → 100644

+159 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

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

		#include <dirent.h>
		#include <libdm/dm.h>
		#include <sys/stat.h>
		#include <sys/sysmacros.h>
		#include <sys/types.h>
		#include "blockdev.h"

		using android::base::Basename;
		using android::base::ErrnoError;
		using android::base::Error;
		using android::base::Result;
		using android::base::ResultError;
		using android::base::StartsWith;
		using android::base::StringPrintf;
		using android::base::unique_fd;
		using android::dm::DeviceMapper;

		// Return the parent device of a partition. Converts e.g. "sda26" into "sda".
		static std::string PartitionParent(const std::string& blockdev) {
		if (blockdev.find('/') != std::string::npos) {
		LOG(ERROR) << __func__ << ": invalid argument " << blockdev;
		return blockdev;
		}
		auto dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/sys/class/block"), closedir};
		if (!dir) {
		return blockdev;
		}
		for (struct dirent* ent = readdir(dir.get()); ent; ent = readdir(dir.get())) {
		if (ent->d_name[0] == '.') {
		continue;
		}
		std::string path = StringPrintf("/sys/class/block/%s/%s", ent->d_name, blockdev.c_str());
		struct stat statbuf;
		if (stat(path.c_str(), &statbuf) >= 0) {
		return ent->d_name;
		}
		}
		return blockdev;
		}

		// Convert a major:minor pair into a block device name.
		static std::string BlockdevName(dev_t dev) {
		auto dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/dev/block"), closedir};
		if (!dir) {
		return {};
		}
		for (struct dirent* ent = readdir(dir.get()); ent; ent = readdir(dir.get())) {
		if (ent->d_name[0] == '.') {
		continue;
		}
		const std::string path = std::string("/dev/block/") + ent->d_name;
		struct stat statbuf;
		if (stat(path.c_str(), &statbuf) >= 0 && dev == statbuf.st_rdev) {
		return ent->d_name;
		}
		}
		return {};
		}

		// Trim whitespace from the end of a string.
		static void rtrim(std::string& s) {
		s.erase(s.find_last_not_of('\n') + 1, s.length());
		}

		// For file `file_path`, retrieve the block device backing the filesystem on
		// which the file exists and return the queue depth of the block device.
		static Result<uint32_t> BlockDeviceQueueDepth(const std::string& file_path) {
		struct stat statbuf;
		int res = stat(file_path.c_str(), &statbuf);
		if (res < 0) {
		return ErrnoError() << "stat(" << file_path << ")";
		}
		std::string blockdev = "/dev/block/" + BlockdevName(statbuf.st_dev);
		LOG(DEBUG) << __func__ << ": " << file_path << " -> " << blockdev;
		if (blockdev.empty()) {
		const std::string err_msg =
		StringPrintf("Failed to convert %u:%u (path %s)", major(statbuf.st_dev),
		minor(statbuf.st_dev), file_path.c_str());
		return ResultError(err_msg, 0);
		}
		auto& dm = DeviceMapper::Instance();
		for (;;) {
		std::optional<std::string> child = dm.GetParentBlockDeviceByPath(blockdev);
		if (!child) {
		break;
		}
		LOG(DEBUG) << __func__ << ": " << blockdev << " -> " << *child;
		blockdev = *child;
		}
		std::optional<std::string> maybe_blockdev = android::dm::ExtractBlockDeviceName(blockdev);
		if (!maybe_blockdev) {
		return ResultError("Failed to remove /dev/block/ prefix from " + blockdev, 0);
		}
		blockdev = PartitionParent(*maybe_blockdev);
		LOG(DEBUG) << __func__ << ": "
		<< "Partition parent: " << blockdev;
		const std::string nr_tags_path =
		StringPrintf("/sys/class/block/%s/mq/0/nr_tags", blockdev.c_str());
		std::string nr_tags;
		if (!android::base::ReadFileToString(nr_tags_path, &nr_tags)) {
		return ResultError("Failed to read " + nr_tags_path, 0);
		}
		rtrim(nr_tags);
		LOG(DEBUG) << __func__ << ": " << file_path << " is backed by /dev/" << blockdev
		<< " and that block device supports queue depth " << nr_tags;
		return strtol(nr_tags.c_str(), NULL, 0);
		}

		// Set 'nr_requests' of `loop_device_path` to the queue depth of the block
		// device backing `file_path`.
		Result<void> ConfigureQueueDepth(const std::string& loop_device_path,
		const std::string& file_path) {
		if (!StartsWith(loop_device_path, "/dev/")) {
		return Error() << "Invalid argument " << loop_device_path;
		}

		const std::string loop_device_name = Basename(loop_device_path);

		const Result<uint32_t> qd = BlockDeviceQueueDepth(file_path);
		if (!qd.ok()) {
		LOG(DEBUG) << __func__ << ": "
		<< "BlockDeviceQueueDepth() returned " << qd.error();
		return ResultError(qd.error());
		}
		const std::string nr_requests = StringPrintf("%u", *qd);
		const std::string sysfs_path =
		StringPrintf("/sys/class/block/%s/queue/nr_requests", loop_device_name.c_str());
		unique_fd sysfs_fd(open(sysfs_path.c_str(), O_RDWR \| O_CLOEXEC));
		if (sysfs_fd == -1) {
		return ErrnoError() << "Failed to open " << sysfs_path;
		}

		const int res = write(sysfs_fd.get(), nr_requests.data(), nr_requests.length());
		if (res < 0) {
		return ErrnoError() << "Failed to write to " << sysfs_path;
		}
		return {};
		}

fs_mgr/blockdev.h

0 → 100644

+21 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <android-base/result.h>
		#include <string>

		android::base::Result<void> ConfigureQueueDepth(const std::string& loop_device_path,
		const std::string& file_path);

fs_mgr/fs_mgr.cpp

+3 −0

Original line number	Diff line number	Diff line
		@@ -70,6 +70,7 @@
		#include <log/log_properties.h>
		#include <logwrap/logwrap.h>

		#include "blockdev.h"
		#include "fs_mgr_priv.h"

		#define KEY_LOC_PROP "ro.crypto.keyfile.userdata"
		@@ -2070,6 +2071,8 @@ static bool PrepareZramBackingDevice(off64_t size) {
		return false;
		}

		ConfigureQueueDepth(loop_device, "/");

		// set block size & direct IO
		unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loop_device.c_str(), O_RDWR \| O_CLOEXEC)));
		if (loop_fd.get() == -1) {