DO NOT MERGE: libsnapshot: Fix test failures on certain configurations. am: 3f96053b38

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2577014

Change-Id: Ib5a3310a0d0903240140455acc321db67c0258be
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

fs_mgr/libsnapshot/snapshot.cpp

@@ -3166,7 +3166,8 @@ Return SnapshotManager::CreateUpdateSnapshots(const DeltaArchiveManifest& manife
               << " writer.GetCowVersion(): " << writer.GetCowVersion();
 
     bool use_compression = IsCompressionEnabled() && dap_metadata.vabc_enabled() &&
-                           !device_->IsRecovery() && cow_format_support;
+                           !device_->IsRecovery() && cow_format_support &&
+                           KernelSupportsCompressedSnapshots();
 
     std::string compression_algorithm;
     if (use_compression) {

fs_mgr/libsnapshot/snapshot_test.cpp

@@ -2760,7 +2760,7 @@ bool IsDaemonRequired() {
         return true;
     }
 
-    return IsUserspaceSnapshotsEnabled();
+    return IsUserspaceSnapshotsEnabled() && KernelSupportsCompressedSnapshots();
 }
 
 bool ShouldUseCompression() {
@@ -2770,7 +2770,7 @@ bool ShouldUseCompression() {
     if (FLAGS_force_config == "vabc") {
         return true;
     }
-    return IsCompressionEnabled();
+    return IsCompressionEnabled() && KernelSupportsCompressedSnapshots();
 }
 
 }  // namespace snapshot

fs_mgr/libsnapshot/utility.cpp

@@ -26,7 +26,9 @@
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <fs_mgr/roots.h>
+#include <libdm/dm.h>
 
+using android::dm::DeviceMapper;
 using android::dm::kSectorSize;
 using android::fiemap::FiemapStatus;
 using android::fs_mgr::EnsurePathMounted;
@@ -208,5 +210,10 @@ bool IsDmSnapshotTestingEnabled() {
     return android::base::GetBoolProperty("snapuserd.test.dm.snapshots", false);
 }
 
+bool KernelSupportsCompressedSnapshots() {
+    auto& dm = DeviceMapper::Instance();
+    return dm.GetTargetByName("user", nullptr);
+}
+
 }  // namespace snapshot
 }  // namespace android

fs_mgr/libsnapshot/utility.h

@@ -129,6 +129,7 @@ std::ostream& operator<<(std::ostream& os, const Now&);
 void AppendExtent(google::protobuf::RepeatedPtrField<chromeos_update_engine::Extent>* extents,
                   uint64_t start_block, uint64_t num_blocks);
 
+bool KernelSupportsCompressedSnapshots();
 bool IsCompressionEnabled();
 
 bool IsUserspaceSnapshotsEnabled();