libsnapshot: use compression_factor in ota

Parse manifest compression_factor and set CowOptions appropriately. This
allows v3 writer to use compression factor in OTA. Updating some
comments about supported compression algorithms

Test: th
Change-Id: I88f254087e536d9e5925064f85317f0acce280ee
diff --git a/fs_mgr/libsnapshot/android/snapshot/snapshot.proto b/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
index 7e97dc0..f2f7fc1 100644
--- a/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
+++ b/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
@@ -103,7 +103,7 @@
     // The old partition size (if none existed, this will be zero).
     uint64 old_partition_size = 10;
 
-    // Compression algorithm (none, gz, or brotli).
+    // Compression algorithm (none, gz, lz4, zstd, or brotli).
     string compression_algorithm = 11;
 
     // Estimated COW size from OTA manifest.
@@ -117,6 +117,9 @@
 
     // Size of v3 operation buffer. Needs to be determined during writer initialization
     uint64 estimated_ops_buffer_size = 15;
+
+    // Max bytes to be compressed at once (4k, 8k, 16k, 32k, 64k, 128k)
+    uint64 compression_factor = 16;
 }
 
 // Next: 8
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index 7df976d..3bcee21 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -60,6 +60,9 @@
 
     // Size of the cow operation buffer; used in v3 only.
     uint64_t op_count_max = 0;
+
+    // Compression factor
+    uint64_t compression_factor = 4096;
 };
 
 // Interface for writing to a snapuserd COW. All operations are ordered; merges
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.h b/fs_mgr/libsnapshot/partition_cow_creator.h
index bd5c8cb..cbd664f 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.h
+++ b/fs_mgr/libsnapshot/partition_cow_creator.h
@@ -59,6 +59,7 @@
     // True if snapuserd COWs are enabled.
     bool using_snapuserd = false;
     std::string compression_algorithm;
+    uint64_t compression_factor;
 
     // True if multi-threaded compression should be enabled
     bool enable_threading;
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 9eb41b2..c12a9e2 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -420,6 +420,7 @@
     status->set_metadata_sectors(0);
     status->set_using_snapuserd(cow_creator->using_snapuserd);
     status->set_compression_algorithm(cow_creator->compression_algorithm);
+    status->set_compression_factor(cow_creator->compression_factor);
     if (cow_creator->enable_threading) {
         status->set_enable_threading(cow_creator->enable_threading);
     }
@@ -3233,8 +3234,10 @@
     }
 
     std::string compression_algorithm;
+    uint64_t compression_factor{};
     if (using_snapuserd) {
         compression_algorithm = dap_metadata.vabc_compression_param();
+        compression_factor = dap_metadata.compression_factor();
         if (compression_algorithm.empty()) {
             // Older OTAs don't set an explicit compression type, so default to gz.
             compression_algorithm = "gz";
@@ -3251,7 +3254,9 @@
             .extra_extents = {},
             .using_snapuserd = using_snapuserd,
             .compression_algorithm = compression_algorithm,
+            .compression_factor = compression_factor,
     };
+
     if (dap_metadata.vabc_feature_set().has_threaded()) {
         cow_creator.enable_threading = dap_metadata.vabc_feature_set().threaded();
     }
@@ -3666,6 +3671,7 @@
     cow_options.batch_write = status.batched_writes();
     cow_options.num_compress_threads = status.enable_threading() ? 2 : 1;
     cow_options.op_count_max = status.estimated_ops_buffer_size();
+    cow_options.compression_factor = status.compression_factor();
     // Disable scratch space for vts tests
     if (device()->IsTestDevice()) {
         cow_options.scratch_space = false;
@@ -3793,6 +3799,7 @@
         ss << "    allocated sectors: " << status.sectors_allocated() << std::endl;
         ss << "    metadata sectors: " << status.metadata_sectors() << std::endl;
         ss << "    compression: " << status.compression_algorithm() << std::endl;
+        ss << "    compression factor: " << status.compression_factor() << std::endl;
         ss << "    merge phase: " << DecideMergePhase(status) << std::endl;
     }
     os << ss.rdbuf();