fs_mgr: Add fs_mgr_overlayfs_is_setup()
Provide a means to determine if overlayfs is currently active with
fs_mgr_overlayfs_is_setup(). Search for current clues in the system
that the overrides are in play. If /mnt/scratch/ is mounted, that
may be enough of a smoking gun because the resource itself may
interfere with operations.
Related to update_engine calling this function to reject performing
an OTA as its operations are incompatible with the overrides.
Test: adb-remount-test.sh
Bug: 120034852
Change-Id: I641163b1559c1a83fe7d0c336d04c10e9956ad3a
diff --git a/fs_mgr/README.overlayfs.md b/fs_mgr/README.overlayfs.md
index 2d42d6c..171936b 100644
--- a/fs_mgr/README.overlayfs.md
+++ b/fs_mgr/README.overlayfs.md
@@ -89,6 +89,12 @@
if higher than 4.6.
- *adb enable-verity* will free up overlayfs and as a bonus the
device will be reverted pristine to before any content was updated.
+ Update engine does not take advantage of this, will perform a full OTA.
+- Update engine will not run if *fs_mgr_overlayfs_is_setup*() reports
+ true as adb remount overrides are incompatable with an OTA for
+ multiple reasons.
+ NB: This is not a problem for fastbootd or recovery as overrides are
+ disabled for those special boot scenarios.
- If dynamic partitions runs out of space, resizing a logical
partition larger may fail because of the scratch partition.
If this happens, either fastboot flashall or adb enable-verity can
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index 57e984d..f2673e7 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -96,6 +96,10 @@
return false;
}
+bool fs_mgr_overlayfs_is_setup() {
+ return false;
+}
+
#else // ALLOW_ADBD_DISABLE_VERITY == 0
namespace {
@@ -924,6 +928,17 @@
return ret;
}
+bool fs_mgr_overlayfs_is_setup() {
+ if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return true;
+ std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
+ fs_mgr_free_fstab);
+ if (fs_mgr_overlayfs_invalid(fstab.get())) return false;
+ for (const auto& mount_point : fs_mgr_candidate_list(fstab.get())) {
+ if (fs_mgr_overlayfs_already_mounted(mount_point)) return true;
+ }
+ return false;
+}
+
#endif // ALLOW_ADBD_DISABLE_VERITY != 0
bool fs_mgr_has_shared_blocks(const std::string& mount_point, const std::string& dev) {
diff --git a/fs_mgr/include/fs_mgr_overlayfs.h b/fs_mgr/include/fs_mgr_overlayfs.h
index deaf4cb..4537e38 100644
--- a/fs_mgr/include/fs_mgr_overlayfs.h
+++ b/fs_mgr/include/fs_mgr_overlayfs.h
@@ -29,6 +29,7 @@
bool fs_mgr_overlayfs_setup(const char* backing = nullptr, const char* mount_point = nullptr,
bool* change = nullptr);
bool fs_mgr_overlayfs_teardown(const char* mount_point = nullptr, bool* change = nullptr);
+bool fs_mgr_overlayfs_is_setup();
bool fs_mgr_has_shared_blocks(const std::string& mount_point, const std::string& dev);
std::string fs_mgr_get_context(const std::string& mount_point);