Use sdcardfs for pass-through mounts.
The pass-through mount is used by MediaProvider to access external
storage. Previously, it was the raw filesystem (eg ext4/f2fs); the
problem with that is that the permissions on that filesystem don't allow
MediaProvider to access all the files it needs to - in particular
directories under Android/
To solve this problem, we can have the pass-through mount sit on top of
sdcardfs instead of the raw filesystem. This means we need to mount
sdcardfs even in case we're using FUSE, but we already needed to do this
anyway for other performance reasons.
Bug: 135341433
Test: atest AdoptableHostTest
Change-Id: I893d5e5076c5096d2d55212f643c9a857242e964
diff --git a/model/EmulatedVolume.cpp b/model/EmulatedVolume.cpp
index 705bf79..99abdd5 100644
--- a/model/EmulatedVolume.cpp
+++ b/model/EmulatedVolume.cpp
@@ -59,13 +59,19 @@
EmulatedVolume::~EmulatedVolume() {}
-status_t EmulatedVolume::doMount() {
+std::string EmulatedVolume::getLabel() {
// We could have migrated storage to an adopted private volume, so always
// call primary storage "emulated" to avoid media rescans.
- std::string label = mLabel;
if (getMountFlags() & MountFlags::kPrimary) {
- label = "emulated";
+ return "emulated";
+ } else {
+ return mLabel;
}
+}
+
+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());
@@ -87,7 +93,53 @@
bool isFuse = base::GetBoolProperty(kPropFuseSnapshot, false);
- if (isFuse) {
+ // Mount sdcardfs regardless of FUSE, since we need it to bind-mount on top of the
+ // FUSE volume for various reasons.
+ if (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 (isFuse && isVisible) {
LOG(INFO) << "Mounting emulated fuse volume";
android::base::unique_fd fd;
int user_id = getMountUserId();
@@ -98,6 +150,7 @@
return -result;
}
+ mFuseMounted = true;
auto callback = getMountCallback();
if (callback) {
bool is_ready = false;
@@ -106,57 +159,8 @@
return -EIO;
}
}
-
- return OK;
- } else if (getMountUserId() != 0) {
- // For sdcardfs, only mount for user 0, since user 0 will always be running
- // and the paths don't change for different users. Trying to double mount
- // will cause sepolicy to scream since sdcardfs prevents 'mounton'
- return OK;
}
- 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));
-
return OK;
}
@@ -167,27 +171,23 @@
// error code and might cause broken behaviour in applications.
KillProcessesUsingPath(getPath());
- bool isFuse = base::GetBoolProperty(kPropFuseSnapshot, false);
- if (isFuse) {
- // We could have migrated storage to an adopted private volume, so always
- // call primary storage "emulated" to avoid media rescans.
- std::string label = mLabel;
- if (getMountFlags() & MountFlags::kPrimary) {
- label = "emulated";
- }
+ if (mFuseMounted) {
+ std::string label = getLabel();
std::string fuse_path(StringPrintf("/mnt/user/%d/%s", getMountUserId(), label.c_str()));
std::string pass_through_path(
StringPrintf("/mnt/pass_through/%d/%s", getMountUserId(), label.c_str()));
- if (UnmountUserFuse(pass_through_path, fuse_path) != OK) {
+ if (UnmountUserFuse(getMountUserId(), getInternalPath(), label) != OK) {
PLOG(INFO) << "UnmountUserFuse failed on emulated fuse volume";
return -errno;
}
rmdir(fuse_path.c_str());
rmdir(pass_through_path.c_str());
- return OK;
- } else if (getMountUserId() != 0) {
+
+ mFuseMounted = false;
+ }
+ if (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;