model/EmulatedVolume.cpp - SHIFTPHONES/android_system_vold - Gitiles

 /*
  * Copyright (C) 2015 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 "EmulatedVolume.h"

 #include "AppFuseUtil.h"
 #include "Utils.h"
 #include "VolumeManager.h"

 #include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/scopeguard.h>
 #include <android-base/stringprintf.h>
 #include <cutils/fs.h>
 #include <private/android_filesystem_config.h>
 #include <utils/Timers.h>

 #include <fcntl.h>
 #include <stdlib.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/sysmacros.h>
 #include <sys/types.h>
 #include <sys/wait.h>

 using android::base::StringPrintf;

 namespace android {
 namespace vold {

 static const char* kSdcardFsPath = "/system/bin/sdcard";

 EmulatedVolume::EmulatedVolume(const std::string& rawPath, int userId)
     : VolumeBase(Type::kEmulated) {
     setId(StringPrintf("emulated;%u", userId));
     mRawPath = rawPath;
     mLabel = "emulated";
     mFuseMounted = false;
     mUseSdcardFs = IsSdcardfsUsed();
     mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, true);
 }

 EmulatedVolume::EmulatedVolume(const std::string& rawPath, dev_t device, const std::string& fsUuid,
                                int userId)
     : VolumeBase(Type::kEmulated) {
     setId(StringPrintf("emulated:%u,%u;%u", major(device), minor(device), userId));
     mRawPath = rawPath;
     mLabel = fsUuid;
     mFuseMounted = false;
     mUseSdcardFs = IsSdcardfsUsed();
     mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, true);
 }

 EmulatedVolume::~EmulatedVolume() {}

 std::string EmulatedVolume::getLabel() {
     // We could have migrated storage to an adopted private volume, so always
     // call primary storage "emulated" to avoid media rescans.
     if (getMountFlags() & MountFlags::kPrimary) {
         return "emulated";
     } else {
         return mLabel;
     }
 }

 // Creates a bind mount from source to target
 static status_t doFuseBindMount(const std::string& source, const std::string& target,
                                 std::list<std::string>& pathsToUnmount) {
     LOG(INFO) << "Bind mounting " << source << " on " << target;
     auto status = BindMount(source, target);
     if (status != OK) {
         return status;
     }
     LOG(INFO) << "Bind mounted " << source << " on " << target;
     pathsToUnmount.push_front(target);
     return OK;
 }

 status_t EmulatedVolume::mountFuseBindMounts() {
     std::string androidSource;
     std::string label = getLabel();
     int userId = getMountUserId();
     std::list<std::string> pathsToUnmount;

     auto unmounter = [&]() {
         LOG(INFO) << "mountFuseBindMounts() unmount scope_guard running";
         for (const auto& path : pathsToUnmount) {
             LOG(INFO) << "Unmounting " << path;
             auto status = UnmountTree(path);
             if (status != OK) {
                 LOG(INFO) << "Failed to unmount " << path;
             } else {
                 LOG(INFO) << "Unmounted " << path;
             }
         }
     };
     auto unmount_guard = android::base::make_scope_guard(unmounter);

     if (mUseSdcardFs) {
         androidSource = StringPrintf("/mnt/runtime/default/%s/%d/Android", label.c_str(), userId);
     } else {
         androidSource = StringPrintf("/%s/%d/Android", mRawPath.c_str(), userId);
     }

     status_t status = OK;
     // Zygote will unmount these dirs if app data isolation is enabled, so apps
     // cannot access these dirs directly.
     std::string androidDataSource = StringPrintf("%s/data", androidSource.c_str());
     std::string androidDataTarget(
             StringPrintf("/mnt/user/%d/%s/%d/Android/data", userId, label.c_str(), userId));
     status = doFuseBindMount(androidDataSource, androidDataTarget, pathsToUnmount);
     if (status != OK) {
         return status;
     }

     std::string androidObbSource = StringPrintf("%s/obb", androidSource.c_str());
     std::string androidObbTarget(
             StringPrintf("/mnt/user/%d/%s/%d/Android/obb", userId, label.c_str(), userId));
     status = doFuseBindMount(androidObbSource, androidObbTarget, pathsToUnmount);
     if (status != OK) {
         return status;
     }

     // Installers get the same view as all other apps, with the sole exception that the
     // OBB dirs (Android/obb) are writable to them. On sdcardfs devices, this requires
     // a special bind mount, since app-private and OBB dirs share the same GID, but we
     // only want to give access to the latter.
     if (mUseSdcardFs) {
         std::string obbSource(StringPrintf("/mnt/runtime/write/%s/%d/Android/obb",
                 label.c_str(), userId));
         std::string obbInstallerTarget(StringPrintf("/mnt/installer/%d/%s/%d/Android/obb",
                 userId, label.c_str(), userId));

         status = doFuseBindMount(obbSource, obbInstallerTarget, pathsToUnmount);
         if (status != OK) {
             return status;
         }
     }

     unmount_guard.Disable();
     return OK;
 }

 status_t EmulatedVolume::unmountFuseBindMounts() {
     std::string label = getLabel();
     int userId = getMountUserId();

     if (mUseSdcardFs || mAppDataIsolationEnabled) {
         std::string installerTarget(
                 StringPrintf("/mnt/installer/%d/%s/%d/Android/obb", userId, label.c_str(), userId));
         LOG(INFO) << "Unmounting " << installerTarget;
         auto status = UnmountTree(installerTarget);
         if (status != OK) {
             LOG(ERROR) << "Failed to unmount " << installerTarget;
             // Intentional continue to try to unmount the other bind mount
         }
     }
     if (mAppDataIsolationEnabled) {
         std::string obbTarget( StringPrintf("/mnt/androidwritable/%d/%s/%d/Android/obb",
                 userId, label.c_str(), userId));
         LOG(INFO) << "Unmounting " << obbTarget;
         auto status = UnmountTree(obbTarget);
         if (status != OK) {
             LOG(ERROR) << "Failed to unmount " << obbTarget;
             // Intentional continue to try to unmount the other bind mount
         }
         std::string dataTarget(StringPrintf("/mnt/androidwritable/%d/%s/%d/Android/data",
                 userId, label.c_str(), userId));
         LOG(INFO) << "Unmounting " << dataTarget;
         status = UnmountTree(dataTarget);
         if (status != OK) {
             LOG(ERROR) << "Failed to unmount " << dataTarget;
             // Intentional continue to try to unmount the other bind mount
         }
     }

     // When app data isolation is enabled, kill all apps that obb/ is mounted, otherwise we should
     // umount the whole Android/ dir.
     if (mAppDataIsolationEnabled) {
         std::string appObbDir(StringPrintf("%s/%d/Android/obb", getPath().c_str(), userId));
         // Here we assume obb/data dirs is mounted as tmpfs, then it must be caused by
         // app data isolation.
         KillProcessesWithTmpfsMountPrefix(appObbDir);
     }

     // Always unmount data and obb dirs as they are mounted to lowerfs for speeding up access.
     std::string androidDataTarget(
             StringPrintf("/mnt/user/%d/%s/%d/Android/data", userId, label.c_str(), userId));

     LOG(INFO) << "Unmounting " << androidDataTarget;
     auto status = UnmountTree(androidDataTarget);
     if (status != OK) {
         return status;
     }
     LOG(INFO) << "Unmounted " << androidDataTarget;

     std::string androidObbTarget(
             StringPrintf("/mnt/user/%d/%s/%d/Android/obb", userId, label.c_str(), userId));

     LOG(INFO) << "Unmounting " << androidObbTarget;
     status = UnmountTree(androidObbTarget);
     if (status != OK) {
         return status;
     }
     LOG(INFO) << "Unmounted " << androidObbTarget;
     return OK;
 }

 status_t EmulatedVolume::unmountSdcardFs() {
     if (!mUseSdcardFs || getMountUserId() != 0) {
         // For sdcardfs, only unmount for user 0, since user 0 will always be running
         // and the paths don't change for different users.
         return OK;
     }

     ForceUnmount(mSdcardFsDefault);
     ForceUnmount(mSdcardFsRead);
     ForceUnmount(mSdcardFsWrite);
     ForceUnmount(mSdcardFsFull);

     rmdir(mSdcardFsDefault.c_str());
     rmdir(mSdcardFsRead.c_str());
     rmdir(mSdcardFsWrite.c_str());
     rmdir(mSdcardFsFull.c_str());

     mSdcardFsDefault.clear();
     mSdcardFsRead.clear();
     mSdcardFsWrite.clear();
     mSdcardFsFull.clear();

     return OK;
 }

 status_t EmulatedVolume::doMount() {
     std::string label = getLabel();
     bool isVisible = getMountFlags() & MountFlags::kVisible;

     mSdcardFsDefault = StringPrintf("/mnt/runtime/default/%s", label.c_str());
     mSdcardFsRead = StringPrintf("/mnt/runtime/read/%s", label.c_str());
     mSdcardFsWrite = StringPrintf("/mnt/runtime/write/%s", label.c_str());
     mSdcardFsFull = StringPrintf("/mnt/runtime/full/%s", label.c_str());

     setInternalPath(mRawPath);
     setPath(StringPrintf("/storage/%s", label.c_str()));

     if (fs_prepare_dir(mSdcardFsDefault.c_str(), 0700, AID_ROOT, AID_ROOT) ||
         fs_prepare_dir(mSdcardFsRead.c_str(), 0700, AID_ROOT, AID_ROOT) ||
         fs_prepare_dir(mSdcardFsWrite.c_str(), 0700, AID_ROOT, AID_ROOT) ||
         fs_prepare_dir(mSdcardFsFull.c_str(), 0700, AID_ROOT, AID_ROOT)) {
         PLOG(ERROR) << getId() << " failed to create mount points";
         return -errno;
     }

     dev_t before = GetDevice(mSdcardFsFull);

     // Mount sdcardfs regardless of FUSE, since we need it to bind-mount on top of the
     // FUSE volume for various reasons.
     if (mUseSdcardFs && getMountUserId() == 0) {
         LOG(INFO) << "Executing sdcardfs";
         int sdcardFsPid;
         if (!(sdcardFsPid = fork())) {
             // clang-format off
             if (execl(kSdcardFsPath, kSdcardFsPath,
                     "-u", "1023", // AID_MEDIA_RW
                     "-g", "1023", // AID_MEDIA_RW
                     "-m",
                     "-w",
                     "-G",
                     "-i",
                     "-o",
                     mRawPath.c_str(),
                     label.c_str(),
                     NULL)) {
                 // clang-format on
                 PLOG(ERROR) << "Failed to exec";
             }

             LOG(ERROR) << "sdcardfs exiting";
             _exit(1);
         }

         if (sdcardFsPid == -1) {
             PLOG(ERROR) << getId() << " failed to fork";
             return -errno;
         }

         nsecs_t start = systemTime(SYSTEM_TIME_BOOTTIME);
         while (before == GetDevice(mSdcardFsFull)) {
             LOG(DEBUG) << "Waiting for sdcardfs to spin up...";
             usleep(50000);  // 50ms

             nsecs_t now = systemTime(SYSTEM_TIME_BOOTTIME);
             if (nanoseconds_to_milliseconds(now - start) > 5000) {
                 LOG(WARNING) << "Timed out while waiting for sdcardfs to spin up";
                 return -ETIMEDOUT;
             }
         }
         /* sdcardfs will have exited already. The filesystem will still be running */
         TEMP_FAILURE_RETRY(waitpid(sdcardFsPid, nullptr, 0));
         sdcardFsPid = 0;
     }

     if (isVisible) {
         // Make sure we unmount sdcardfs if we bail out with an error below
         auto sdcardfs_unmounter = [&]() {
             LOG(INFO) << "sdcardfs_unmounter scope_guard running";
             unmountSdcardFs();
         };
         auto sdcardfs_guard = android::base::make_scope_guard(sdcardfs_unmounter);

         LOG(INFO) << "Mounting emulated fuse volume";
         android::base::unique_fd fd;
         int user_id = getMountUserId();
         auto volumeRoot = getRootPath();

         // Make sure Android/ dirs exist for bind mounting
         status_t res = PrepareAndroidDirs(volumeRoot);
         if (res != OK) {
             LOG(ERROR) << "Failed to prepare Android/ directories";
             return res;
         }

         res = MountUserFuse(user_id, getInternalPath(), label, &fd);
         if (res != 0) {
             PLOG(ERROR) << "Failed to mount emulated fuse volume";
             return res;
         }

         mFuseMounted = true;
         auto fuse_unmounter = [&]() {
             LOG(INFO) << "fuse_unmounter scope_guard running";
             fd.reset();
             if (UnmountUserFuse(user_id, getInternalPath(), label) != OK) {
                 PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
             }
             mFuseMounted = false;
         };
         auto fuse_guard = android::base::make_scope_guard(fuse_unmounter);

         auto callback = getMountCallback();
         if (callback) {
             bool is_ready = false;
             callback->onVolumeChecking(std::move(fd), getPath(), getInternalPath(), &is_ready);
             if (!is_ready) {
                 return -EIO;
             }
         }

         // Only do the bind-mounts when we know for sure the FUSE daemon can resolve the path.
         res = mountFuseBindMounts();
         if (res != OK) {
             return res;
         }

         ConfigureReadAheadForFuse(GetFuseMountPathForUser(user_id, label), 256u);

         // By default, FUSE has a max_dirty ratio of 1%. This means that out of
         // all dirty pages in the system, only 1% is allowed to belong to any
         // FUSE filesystem. The reason this is in place is that FUSE
         // filesystems shouldn't be trusted by default; a FUSE filesystem could
         // take up say 100% of dirty pages, and subsequently refuse to write
         // them back to storage.  The kernel will then apply rate-limiting, and
         // block other tasks from writing.  For this particular FUSE filesystem
         // however, we trust the implementation, because it is a part of the
         // Android platform. So use the default ratio of 100%.
         //
         // The reason we're setting this is that there's a suspicion that the
         // kernel starts rate-limiting the FUSE filesystem under extreme
         // memory pressure scenarios. While the kernel will only rate limit if
         // the writeback can't keep up with the write rate, under extreme
         // memory pressure the write rate may dip as well, in which case FUSE
         // writes to a 1% max_ratio filesystem are throttled to an extreme amount.
         //
         // To prevent this, just give FUSE 40% max_ratio, meaning it can take
         // up to 40% of all dirty pages in the system.
         ConfigureMaxDirtyRatioForFuse(GetFuseMountPathForUser(user_id, label), 40u);

         // All mounts where successful, disable scope guards
         sdcardfs_guard.Disable();
         fuse_guard.Disable();
     }

     return OK;
 }

 status_t EmulatedVolume::doUnmount() {
     int userId = getMountUserId();

     // Kill all processes using the filesystem before we unmount it. If we
     // unmount the filesystem first, most file system operations will return
     // ENOTCONN until the unmount completes. This is an exotic and unusual
     // error code and might cause broken behaviour in applications.
     if (mFuseMounted) {
         // For FUSE specifically, we have an emulated volume per user, so only kill
         // processes using files from this particular user.
         std::string user_path(StringPrintf("%s/%d", getPath().c_str(), getMountUserId()));
         LOG(INFO) << "Killing all processes referencing " << user_path;
         KillProcessesUsingPath(user_path);
     } else {
         KillProcessesUsingPath(getPath());
     }

     if (mFuseMounted) {
         std::string label = getLabel();

         // Ignoring unmount return status because we do want to try to unmount
         // the rest cleanly.
         unmountFuseBindMounts();

         if (UnmountUserFuse(userId, getInternalPath(), label) != OK) {
             PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
             return -errno;
         }

         mFuseMounted = false;
     }

     return unmountSdcardFs();
 }

 std::string EmulatedVolume::getRootPath() const {
     int user_id = getMountUserId();
     std::string volumeRoot = StringPrintf("%s/%d", getInternalPath().c_str(), user_id);

     return volumeRoot;
 }

 }  // namespace vold
 }  // namespace android
	/*
	* Copyright (C) 2015 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 "EmulatedVolume.h"

	#include "AppFuseUtil.h"
	#include "Utils.h"
	#include "VolumeManager.h"

	#include <android-base/logging.h>
	#include <android-base/properties.h>
	#include <android-base/scopeguard.h>
	#include <android-base/stringprintf.h>
	#include <cutils/fs.h>
	#include <private/android_filesystem_config.h>
	#include <utils/Timers.h>

	#include <fcntl.h>
	#include <stdlib.h>
	#include <sys/mount.h>
	#include <sys/stat.h>
	#include <sys/sysmacros.h>
	#include <sys/types.h>
	#include <sys/wait.h>

	using android::base::StringPrintf;

	namespace android {
	namespace vold {

	static const char* kSdcardFsPath = "/system/bin/sdcard";

	EmulatedVolume::EmulatedVolume(const std::string& rawPath, int userId)
	: VolumeBase(Type::kEmulated) {
	setId(StringPrintf("emulated;%u", userId));
	mRawPath = rawPath;
	mLabel = "emulated";
	mFuseMounted = false;
	mUseSdcardFs = IsSdcardfsUsed();
	mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, true);
	}

	EmulatedVolume::EmulatedVolume(const std::string& rawPath, dev_t device, const std::string& fsUuid,
	int userId)
	: VolumeBase(Type::kEmulated) {
	setId(StringPrintf("emulated:%u,%u;%u", major(device), minor(device), userId));
	mRawPath = rawPath;
	mLabel = fsUuid;
	mFuseMounted = false;
	mUseSdcardFs = IsSdcardfsUsed();
	mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, true);
	}

	EmulatedVolume::~EmulatedVolume() {}

	std::string EmulatedVolume::getLabel() {
	// We could have migrated storage to an adopted private volume, so always
	// call primary storage "emulated" to avoid media rescans.
	if (getMountFlags() & MountFlags::kPrimary) {
	return "emulated";
	} else {
	return mLabel;
	}
	}

	// Creates a bind mount from source to target
	static status_t doFuseBindMount(const std::string& source, const std::string& target,
	std::list<std::string>& pathsToUnmount) {
	LOG(INFO) << "Bind mounting " << source << " on " << target;
	auto status = BindMount(source, target);
	if (status != OK) {
	return status;
	}
	LOG(INFO) << "Bind mounted " << source << " on " << target;
	pathsToUnmount.push_front(target);
	return OK;
	}

	status_t EmulatedVolume::mountFuseBindMounts() {
	std::string androidSource;
	std::string label = getLabel();
	int userId = getMountUserId();
	std::list<std::string> pathsToUnmount;

	auto unmounter = [&]() {
	LOG(INFO) << "mountFuseBindMounts() unmount scope_guard running";
	for (const auto& path : pathsToUnmount) {
	LOG(INFO) << "Unmounting " << path;
	auto status = UnmountTree(path);
	if (status != OK) {
	LOG(INFO) << "Failed to unmount " << path;
	} else {
	LOG(INFO) << "Unmounted " << path;
	}
	}
	};
	auto unmount_guard = android::base::make_scope_guard(unmounter);

	if (mUseSdcardFs) {
	androidSource = StringPrintf("/mnt/runtime/default/%s/%d/Android", label.c_str(), userId);
	} else {
	androidSource = StringPrintf("/%s/%d/Android", mRawPath.c_str(), userId);
	}

	status_t status = OK;
	// Zygote will unmount these dirs if app data isolation is enabled, so apps
	// cannot access these dirs directly.
	std::string androidDataSource = StringPrintf("%s/data", androidSource.c_str());
	std::string androidDataTarget(
	StringPrintf("/mnt/user/%d/%s/%d/Android/data", userId, label.c_str(), userId));
	status = doFuseBindMount(androidDataSource, androidDataTarget, pathsToUnmount);
	if (status != OK) {
	return status;
	}

	std::string androidObbSource = StringPrintf("%s/obb", androidSource.c_str());
	std::string androidObbTarget(
	StringPrintf("/mnt/user/%d/%s/%d/Android/obb", userId, label.c_str(), userId));
	status = doFuseBindMount(androidObbSource, androidObbTarget, pathsToUnmount);
	if (status != OK) {
	return status;
	}

	// Installers get the same view as all other apps, with the sole exception that the
	// OBB dirs (Android/obb) are writable to them. On sdcardfs devices, this requires
	// a special bind mount, since app-private and OBB dirs share the same GID, but we
	// only want to give access to the latter.
	if (mUseSdcardFs) {
	std::string obbSource(StringPrintf("/mnt/runtime/write/%s/%d/Android/obb",
	label.c_str(), userId));
	std::string obbInstallerTarget(StringPrintf("/mnt/installer/%d/%s/%d/Android/obb",
	userId, label.c_str(), userId));

	status = doFuseBindMount(obbSource, obbInstallerTarget, pathsToUnmount);
	if (status != OK) {
	return status;
	}
	}

	unmount_guard.Disable();
	return OK;
	}

	status_t EmulatedVolume::unmountFuseBindMounts() {
	std::string label = getLabel();
	int userId = getMountUserId();

	if (mUseSdcardFs \|\| mAppDataIsolationEnabled) {
	std::string installerTarget(
	StringPrintf("/mnt/installer/%d/%s/%d/Android/obb", userId, label.c_str(), userId));
	LOG(INFO) << "Unmounting " << installerTarget;
	auto status = UnmountTree(installerTarget);
	if (status != OK) {
	LOG(ERROR) << "Failed to unmount " << installerTarget;
	// Intentional continue to try to unmount the other bind mount
	}
	}
	if (mAppDataIsolationEnabled) {
	std::string obbTarget( StringPrintf("/mnt/androidwritable/%d/%s/%d/Android/obb",
	userId, label.c_str(), userId));
	LOG(INFO) << "Unmounting " << obbTarget;
	auto status = UnmountTree(obbTarget);
	if (status != OK) {
	LOG(ERROR) << "Failed to unmount " << obbTarget;
	// Intentional continue to try to unmount the other bind mount
	}
	std::string dataTarget(StringPrintf("/mnt/androidwritable/%d/%s/%d/Android/data",
	userId, label.c_str(), userId));
	LOG(INFO) << "Unmounting " << dataTarget;
	status = UnmountTree(dataTarget);
	if (status != OK) {
	LOG(ERROR) << "Failed to unmount " << dataTarget;
	// Intentional continue to try to unmount the other bind mount
	}
	}

	// When app data isolation is enabled, kill all apps that obb/ is mounted, otherwise we should
	// umount the whole Android/ dir.
	if (mAppDataIsolationEnabled) {
	std::string appObbDir(StringPrintf("%s/%d/Android/obb", getPath().c_str(), userId));
	// Here we assume obb/data dirs is mounted as tmpfs, then it must be caused by
	// app data isolation.
	KillProcessesWithTmpfsMountPrefix(appObbDir);
	}

	// Always unmount data and obb dirs as they are mounted to lowerfs for speeding up access.
	std::string androidDataTarget(
	StringPrintf("/mnt/user/%d/%s/%d/Android/data", userId, label.c_str(), userId));

	LOG(INFO) << "Unmounting " << androidDataTarget;
	auto status = UnmountTree(androidDataTarget);
	if (status != OK) {
	return status;
	}
	LOG(INFO) << "Unmounted " << androidDataTarget;

	std::string androidObbTarget(
	StringPrintf("/mnt/user/%d/%s/%d/Android/obb", userId, label.c_str(), userId));

	LOG(INFO) << "Unmounting " << androidObbTarget;
	status = UnmountTree(androidObbTarget);
	if (status != OK) {
	return status;
	}
	LOG(INFO) << "Unmounted " << androidObbTarget;
	return OK;
	}

	status_t EmulatedVolume::unmountSdcardFs() {
	if (!mUseSdcardFs \|\| getMountUserId() != 0) {
	// For sdcardfs, only unmount for user 0, since user 0 will always be running
	// and the paths don't change for different users.
	return OK;
	}

	ForceUnmount(mSdcardFsDefault);
	ForceUnmount(mSdcardFsRead);
	ForceUnmount(mSdcardFsWrite);
	ForceUnmount(mSdcardFsFull);

	rmdir(mSdcardFsDefault.c_str());
	rmdir(mSdcardFsRead.c_str());
	rmdir(mSdcardFsWrite.c_str());
	rmdir(mSdcardFsFull.c_str());

	mSdcardFsDefault.clear();
	mSdcardFsRead.clear();
	mSdcardFsWrite.clear();
	mSdcardFsFull.clear();

	return OK;
	}

	status_t EmulatedVolume::doMount() {
	std::string label = getLabel();
	bool isVisible = getMountFlags() & MountFlags::kVisible;

	mSdcardFsDefault = StringPrintf("/mnt/runtime/default/%s", label.c_str());
	mSdcardFsRead = StringPrintf("/mnt/runtime/read/%s", label.c_str());
	mSdcardFsWrite = StringPrintf("/mnt/runtime/write/%s", label.c_str());
	mSdcardFsFull = StringPrintf("/mnt/runtime/full/%s", label.c_str());

	setInternalPath(mRawPath);
	setPath(StringPrintf("/storage/%s", label.c_str()));

	if (fs_prepare_dir(mSdcardFsDefault.c_str(), 0700, AID_ROOT, AID_ROOT) \|\|
	fs_prepare_dir(mSdcardFsRead.c_str(), 0700, AID_ROOT, AID_ROOT) \|\|
	fs_prepare_dir(mSdcardFsWrite.c_str(), 0700, AID_ROOT, AID_ROOT) \|\|
	fs_prepare_dir(mSdcardFsFull.c_str(), 0700, AID_ROOT, AID_ROOT)) {
	PLOG(ERROR) << getId() << " failed to create mount points";
	return -errno;
	}

	dev_t before = GetDevice(mSdcardFsFull);

	// Mount sdcardfs regardless of FUSE, since we need it to bind-mount on top of the
	// FUSE volume for various reasons.
	if (mUseSdcardFs && getMountUserId() == 0) {
	LOG(INFO) << "Executing sdcardfs";
	int sdcardFsPid;
	if (!(sdcardFsPid = fork())) {
	// clang-format off
	if (execl(kSdcardFsPath, kSdcardFsPath,
	"-u", "1023", // AID_MEDIA_RW
	"-g", "1023", // AID_MEDIA_RW
	"-m",
	"-w",
	"-G",
	"-i",
	"-o",
	mRawPath.c_str(),
	label.c_str(),
	NULL)) {
	// clang-format on
	PLOG(ERROR) << "Failed to exec";
	}

	LOG(ERROR) << "sdcardfs exiting";
	_exit(1);
	}

	if (sdcardFsPid == -1) {
	PLOG(ERROR) << getId() << " failed to fork";
	return -errno;
	}

	nsecs_t start = systemTime(SYSTEM_TIME_BOOTTIME);
	while (before == GetDevice(mSdcardFsFull)) {
	LOG(DEBUG) << "Waiting for sdcardfs to spin up...";
	usleep(50000); // 50ms

	nsecs_t now = systemTime(SYSTEM_TIME_BOOTTIME);
	if (nanoseconds_to_milliseconds(now - start) > 5000) {
	LOG(WARNING) << "Timed out while waiting for sdcardfs to spin up";
	return -ETIMEDOUT;
	}
	}
	/* sdcardfs will have exited already. The filesystem will still be running */
	TEMP_FAILURE_RETRY(waitpid(sdcardFsPid, nullptr, 0));
	sdcardFsPid = 0;
	}

	if (isVisible) {
	// Make sure we unmount sdcardfs if we bail out with an error below
	auto sdcardfs_unmounter = [&]() {
	LOG(INFO) << "sdcardfs_unmounter scope_guard running";
	unmountSdcardFs();
	};
	auto sdcardfs_guard = android::base::make_scope_guard(sdcardfs_unmounter);

	LOG(INFO) << "Mounting emulated fuse volume";
	android::base::unique_fd fd;
	int user_id = getMountUserId();
	auto volumeRoot = getRootPath();

	// Make sure Android/ dirs exist for bind mounting
	status_t res = PrepareAndroidDirs(volumeRoot);
	if (res != OK) {
	LOG(ERROR) << "Failed to prepare Android/ directories";
	return res;
	}

	res = MountUserFuse(user_id, getInternalPath(), label, &fd);
	if (res != 0) {
	PLOG(ERROR) << "Failed to mount emulated fuse volume";
	return res;
	}

	mFuseMounted = true;
	auto fuse_unmounter = [&]() {
	LOG(INFO) << "fuse_unmounter scope_guard running";
	fd.reset();
	if (UnmountUserFuse(user_id, getInternalPath(), label) != OK) {
	PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
	}
	mFuseMounted = false;
	};
	auto fuse_guard = android::base::make_scope_guard(fuse_unmounter);

	auto callback = getMountCallback();
	if (callback) {
	bool is_ready = false;
	callback->onVolumeChecking(std::move(fd), getPath(), getInternalPath(), &is_ready);
	if (!is_ready) {
	return -EIO;
	}
	}

	// Only do the bind-mounts when we know for sure the FUSE daemon can resolve the path.
	res = mountFuseBindMounts();
	if (res != OK) {
	return res;
	}

	ConfigureReadAheadForFuse(GetFuseMountPathForUser(user_id, label), 256u);

	// By default, FUSE has a max_dirty ratio of 1%. This means that out of
	// all dirty pages in the system, only 1% is allowed to belong to any
	// FUSE filesystem. The reason this is in place is that FUSE
	// filesystems shouldn't be trusted by default; a FUSE filesystem could
	// take up say 100% of dirty pages, and subsequently refuse to write
	// them back to storage. The kernel will then apply rate-limiting, and
	// block other tasks from writing. For this particular FUSE filesystem
	// however, we trust the implementation, because it is a part of the
	// Android platform. So use the default ratio of 100%.
	//
	// The reason we're setting this is that there's a suspicion that the
	// kernel starts rate-limiting the FUSE filesystem under extreme
	// memory pressure scenarios. While the kernel will only rate limit if
	// the writeback can't keep up with the write rate, under extreme
	// memory pressure the write rate may dip as well, in which case FUSE
	// writes to a 1% max_ratio filesystem are throttled to an extreme amount.
	//
	// To prevent this, just give FUSE 40% max_ratio, meaning it can take
	// up to 40% of all dirty pages in the system.
	ConfigureMaxDirtyRatioForFuse(GetFuseMountPathForUser(user_id, label), 40u);

	// All mounts where successful, disable scope guards
	sdcardfs_guard.Disable();
	fuse_guard.Disable();
	}

	return OK;
	}

	status_t EmulatedVolume::doUnmount() {
	int userId = getMountUserId();

	// Kill all processes using the filesystem before we unmount it. If we
	// unmount the filesystem first, most file system operations will return
	// ENOTCONN until the unmount completes. This is an exotic and unusual
	// error code and might cause broken behaviour in applications.
	if (mFuseMounted) {
	// For FUSE specifically, we have an emulated volume per user, so only kill
	// processes using files from this particular user.
	std::string user_path(StringPrintf("%s/%d", getPath().c_str(), getMountUserId()));
	LOG(INFO) << "Killing all processes referencing " << user_path;
	KillProcessesUsingPath(user_path);
	} else {
	KillProcessesUsingPath(getPath());
	}

	if (mFuseMounted) {
	std::string label = getLabel();

	// Ignoring unmount return status because we do want to try to unmount
	// the rest cleanly.
	unmountFuseBindMounts();

	if (UnmountUserFuse(userId, getInternalPath(), label) != OK) {
	PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
	return -errno;
	}

	mFuseMounted = false;
	}

	return unmountSdcardFs();
	}

	std::string EmulatedVolume::getRootPath() const {
	int user_id = getMountUserId();
	std::string volumeRoot = StringPrintf("%s/%d", getInternalPath().c_str(), user_id);

	return volumeRoot;
	}

	} // namespace vold
	} // namespace android