Reduce the queue depth of loop devices used by the zram driver am: 1a9cad816d (e21b057b) · Commits · e / os / android_system_core

fs_mgr/Android.bp

+1 −0

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

fs_mgr/blockdev.cpp

0 → 100644

+159 −0

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

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

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

			ConfigureQueueDepth(loop_device, "/");

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