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/PublicVolume.cpp b/model/PublicVolume.cpp
index 007fd60..e1606a3 100644
--- a/model/PublicVolume.cpp
+++ b/model/PublicVolume.cpp
@@ -95,6 +95,7 @@
}
status_t PublicVolume::doMount() {
+ bool isVisible = getMountFlags() & MountFlags::kVisible;
readMetadata();
if (mFsType == "vfat" && vfat::IsSupported()) {
@@ -126,7 +127,7 @@
mSdcardFsFull = StringPrintf("/mnt/runtime/full/%s", stableName.c_str());
setInternalPath(mRawPath);
- if (getMountFlags() & MountFlags::kVisible) {
+ if (isVisible) {
setPath(StringPrintf("/storage/%s", stableName.c_str()));
} else {
setPath(mRawPath);
@@ -154,7 +155,7 @@
initAsecStage();
}
- if (!(getMountFlags() & MountFlags::kVisible)) {
+ if (!isVisible) {
// Not visible to apps, so no need to spin up sdcardfs or FUSE
return OK;
}
@@ -169,30 +170,6 @@
dev_t before = GetDevice(mSdcardFsFull);
- bool isFuse = base::GetBoolProperty(kPropFuseSnapshot, false);
- if (isFuse) {
- LOG(INFO) << "Mounting public fuse volume";
- android::base::unique_fd fd;
- int user_id = getMountUserId();
- int result = MountUserFuse(user_id, getInternalPath(), stableName, &fd);
-
- if (result != 0) {
- LOG(ERROR) << "Failed to mount public fuse volume";
- return -result;
- }
-
- auto callback = getMountCallback();
- if (callback) {
- bool is_ready = false;
- callback->onVolumeChecking(std::move(fd), getPath(), getInternalPath(), &is_ready);
- if (!is_ready) {
- return -EIO;
- }
- }
-
- return OK;
- }
-
int sdcardFsPid;
if (!(sdcardFsPid = fork())) {
if (getMountFlags() & MountFlags::kPrimary) {
@@ -245,6 +222,31 @@
/* sdcardfs will have exited already. The filesystem will still be running */
TEMP_FAILURE_RETRY(waitpid(sdcardFsPid, nullptr, 0));
+ bool isFuse = base::GetBoolProperty(kPropFuseSnapshot, false);
+ if (isFuse) {
+ // We need to mount FUSE *after* sdcardfs, since the FUSE daemon may depend
+ // on sdcardfs being up.
+ LOG(INFO) << "Mounting public fuse volume";
+ android::base::unique_fd fd;
+ int user_id = getMountUserId();
+ int result = MountUserFuse(user_id, getInternalPath(), stableName, &fd);
+
+ if (result != 0) {
+ LOG(ERROR) << "Failed to mount public fuse volume";
+ return -result;
+ }
+
+ mFuseMounted = true;
+ auto callback = getMountCallback();
+ if (callback) {
+ bool is_ready = false;
+ callback->onVolumeChecking(std::move(fd), getPath(), getInternalPath(), &is_ready);
+ if (!is_ready) {
+ return -EIO;
+ }
+ }
+ }
+
return OK;
}
@@ -255,30 +257,26 @@
// error code and might cause broken behaviour in applications.
KillProcessesUsingPath(getPath());
- bool isFuse = base::GetBoolProperty(kPropFuseSnapshot, false);
- if (isFuse) {
+ if (mFuseMounted) {
// Use UUID as stable name, if available
std::string stableName = getId();
if (!mFsUuid.empty()) {
stableName = mFsUuid;
}
+ if (UnmountUserFuse(getMountUserId(), getInternalPath(), stableName) != OK) {
+ PLOG(INFO) << "UnmountUserFuse failed on public fuse volume";
+ return -errno;
+ }
+
std::string fuse_path(
StringPrintf("/mnt/user/%d/%s", getMountUserId(), stableName.c_str()));
std::string pass_through_path(
StringPrintf("/mnt/pass_through/%d/%s", getMountUserId(), stableName.c_str()));
- if (UnmountUserFuse(pass_through_path, fuse_path) != OK) {
- PLOG(INFO) << "UnmountUserFuse failed on public fuse volume";
- return -errno;
- }
- ForceUnmount(kAsecPath);
- ForceUnmount(mRawPath);
-
rmdir(fuse_path.c_str());
rmdir(pass_through_path.c_str());
- rmdir(mRawPath.c_str());
- mRawPath.clear();
- return OK;
+
+ mFuseMounted = false;
}
ForceUnmount(kAsecPath);