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Bind mount Android/data and Android/obb individually.

Browse source 
Because we want all other paths (in particular Android/media) to go
through FUSE.

Also use scope_guard to make unwinding some failures easier.

Bug: 151272568
Test: atest AdoptableHostTest
Change-Id: Ib487b9071b5b212c7bb12ce54f80c96d98acaef5
This commit is contained in:
Martijn Coenen 2020-03-16 14:37:33 +01:00
parent b6488f3f04
commit 449a7d8ae0
2 changed files with 110 additions and 62 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

152
model/EmulatedVolume.cpp
View file

@ -22,6 +22,7 @@
#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>
@ -48,7 +49,6 @@ EmulatedVolume::EmulatedVolume(const std::string& rawPath, int userId)
mRawPath = rawPath;
mLabel = "emulated";
mFuseMounted = false;
mAndroidMounted = false;
mUseSdcardFs = IsFilesystemSupported("sdcardfs");
mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, false);
}
@ -60,7 +60,6 @@ EmulatedVolume::EmulatedVolume(const std::string& rawPath, dev_t device, const s
mRawPath = rawPath;
mLabel = fsUuid;
mFuseMounted = false;
mAndroidMounted = false;
mUseSdcardFs = IsFilesystemSupported("sdcardfs");
mAppDataIsolationEnabled = base::GetBoolProperty(kVoldAppDataIsolationEnabled, false);
}
@ -78,22 +77,37 @@ std::string EmulatedVolume::getLabel() {
}
// Creates a bind mount from source to target
static status_t doFuseBindMount(const std::string& source, const std::string& 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() {
CHECK(!mAndroidMounted);
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);
@ -105,38 +119,43 @@ status_t EmulatedVolume::mountFuseBindMounts() {
// When app data isolation is enabled, obb/ will be mounted per app, otherwise we should
// bind mount the whole Android/ to speed up reading.
if (!mAppDataIsolationEnabled) {
std::string androidTarget(
StringPrintf("/mnt/user/%d/%s/%d/Android", userId, label.c_str(), userId));
status = doFuseBindMount(androidSource, androidTarget);
}
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;
}
mAndroidMounted = true;
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) {
return OK;
}
if (mUseSdcardFs) {
std::string installerSource(
StringPrintf("/mnt/runtime/write/%s/%d/Android/obb", label.c_str(), userId));
std::string installerTarget(
StringPrintf("/mnt/installer/%d/%s/%d/Android/obb", userId, label.c_str(), userId));
status = doFuseBindMount(installerSource, installerTarget);
status = doFuseBindMount(installerSource, installerTarget, pathsToUnmount);
if (status != OK) {
return status;
}
}
unmount_guard.Disable();
return OK;
}
status_t EmulatedVolume::unmountFuseBindMounts() {
CHECK(mAndroidMounted);
std::string label = getLabel();
int userId = getMountUserId();
@ -156,16 +175,51 @@ status_t EmulatedVolume::unmountFuseBindMounts() {
std::string appObbDir(StringPrintf("%s/%d/Android/obb", getPath().c_str(), userId));
KillProcessesWithMountPrefix(appObbDir);
} else {
std::string androidTarget(
StringPrintf("/mnt/user/%d/%s/%d/Android", userId, label.c_str(), userId));
std::string androidDataTarget(
StringPrintf("/mnt/user/%d/%s/%d/Android/data", userId, label.c_str(), userId));
LOG(INFO) << "Unmounting " << androidTarget;
auto status = UnmountTree(androidTarget);
LOG(INFO) << "Unmounting " << androidDataTarget;
auto status = UnmountTree(androidDataTarget);
if (status != OK) {
return status;
}
LOG(INFO) << "Unmounted " << androidTarget;
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;
}
@ -239,7 +293,15 @@ status_t EmulatedVolume::doMount() {
TEMP_FAILURE_RETRY(waitpid(sdcardFsPid, nullptr, 0));
sdcardFsPid = 0;
}
if (isFuse && 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();
@ -259,13 +321,21 @@ status_t EmulatedVolume::doMount() {
}
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) {
fd.reset();
doUnmount();
return -EIO;
}
}
@ -273,12 +343,14 @@ status_t EmulatedVolume::doMount() {
// Only do the bind-mounts when we know for sure the FUSE daemon can resolve the path.
res = mountFuseBindMounts();
if (res != OK) {
fd.reset();
doUnmount();
}
return res;
}
// All mounts where successful, disable scope guards
sdcardfs_guard.Disable();
fuse_guard.Disable();
}
return OK;
}
@ -304,10 +376,8 @@ status_t EmulatedVolume::doUnmount() {
// Ignoring unmount return status because we do want to try to unmount
// the rest cleanly.
if (mAndroidMounted) {
unmountFuseBindMounts();
mAndroidMounted = false;
}
if (UnmountUserFuse(userId, getInternalPath(), label) != OK) {
PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
return -errno;
@ -315,28 +385,8 @@ status_t EmulatedVolume::doUnmount() {
mFuseMounted = false;
}
if (getMountUserId() != 0 || !mUseSdcardFs) {
// 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;
return unmountSdcardFs();
}
std::string EmulatedVolume::getRootPath() const {

4
model/EmulatedVolume.h
View file

@ -48,6 +48,7 @@ class EmulatedVolume : public VolumeBase {
status_t doUnmount() override;
private:
status_t unmountSdcardFs();
status_t mountFuseBindMounts();
status_t unmountFuseBindMounts();
@ -63,9 +64,6 @@ class EmulatedVolume : public VolumeBase {
/* Whether we mounted FUSE for this volume */
bool mFuseMounted;
/* Whether we mounted Android/ for this volume */
bool mAndroidMounted;
/* Whether to use sdcardfs for this volume */
bool mUseSdcardFs;