Support bind mounting volumes into other volume's mountpoint.
With the way the FUSE mount point are currently setup for emulated
volumes, there can be multiple paths that serve the same files on the
lower filesystem; eg
* /mnt/user/0/emulated/0/Android
* /mnt/user/10/emulated/0/Android
both refer to the same file on the lower filesystem:
* /data/media/0/Android
this is normally not a problem, because cross-user file access is not
allowed, and so the FUSE daemon won't serve files for other users.
With clone profiles this is no longer true however, as their volumes
are accessible by each other.
So, it can happen that an app running in clone profile 10 accesses
"/mnt/user/10/emulated/0/Android", which would be served by the FUSE
daemon for the user 10 filesystem.
At the same time, an app running in the owner profile 0 accesses
"mnt/user/0/emulated/0/Android", which would be served by the FUSE
daemon for the user 0 filesystem.
This can cause page cache inconsistencies, because multiple FUSE daemons
can be running on top of the same entries in the lower filesystem.
To prevent this, use bind mounts to make sure that cross-profile
accesses actually end up in the FUSE daemon to which the volume
belongs: "/mnt/user/10/emulated/0" is bind-mounted to
"/mnt/user/0/emulated/0", and vice-versa.
Bug: 228271997
Test: manual
Change-Id: Iefcbc813670628b329a1a5d408b6126b84991e09
diff --git a/VoldNativeService.cpp b/VoldNativeService.cpp
index ea2c98c..601323f 100644
--- a/VoldNativeService.cpp
+++ b/VoldNativeService.cpp
@@ -182,11 +182,13 @@
return translate(VolumeManager::Instance()->abortFuse());
}
-binder::Status VoldNativeService::onUserAdded(int32_t userId, int32_t userSerial) {
+binder::Status VoldNativeService::onUserAdded(int32_t userId, int32_t userSerial,
+ int32_t sharesStorageWithUserId) {
ENFORCE_SYSTEM_OR_ROOT;
ACQUIRE_LOCK;
- return translate(VolumeManager::Instance()->onUserAdded(userId, userSerial));
+ return translate(
+ VolumeManager::Instance()->onUserAdded(userId, userSerial, sharesStorageWithUserId));
}
binder::Status VoldNativeService::onUserRemoved(int32_t userId) {