Merge "COW partition creator uses DmSnapshotCowSizeCalculator"
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.cpp b/fs_mgr/libsnapshot/partition_cow_creator.cpp
index eedc1cd..77315b4 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.cpp
+++ b/fs_mgr/libsnapshot/partition_cow_creator.cpp
@@ -17,8 +17,9 @@
#include <math.h>
#include <android-base/logging.h>
-
#include <android/snapshot/snapshot.pb.h>
+
+#include "dm_snapshot_internals.h"
#include "utility.h"
using android::dm::kSectorSize;
@@ -33,13 +34,6 @@
namespace android {
namespace snapshot {
-// Round |d| up to a multiple of |block_size|.
-static uint64_t RoundUp(double d, uint64_t block_size) {
- uint64_t ret = ((uint64_t)ceil(d) + block_size - 1) / block_size * block_size;
- CHECK(ret >= d) << "Can't round " << d << " up to a multiple of " << block_size;
- return ret;
-}
-
// Intersect two linear extents. If no intersection, return an extent with length 0.
static std::unique_ptr<Extent> Intersect(Extent* target_extent, Extent* existing_extent) {
// Convert target_extent and existing_extent to linear extents. Zero extents
@@ -68,33 +62,58 @@
return false;
}
-std::optional<uint64_t> PartitionCowCreator::GetCowSize(uint64_t snapshot_size) {
- // TODO: Use |operations|. to determine a minimum COW size.
- // kCowEstimateFactor is good for prototyping but we can't use that in production.
- static constexpr double kCowEstimateFactor = 1.05;
- auto cow_size = RoundUp(snapshot_size * kCowEstimateFactor, kDefaultBlockSize);
- return cow_size;
+uint64_t PartitionCowCreator::GetCowSize() {
+ // WARNING: The origin partition should be READ-ONLY
+ const uint64_t logical_block_size = current_metadata->logical_block_size();
+ const unsigned int sectors_per_block = logical_block_size / kSectorSize;
+ DmSnapCowSizeCalculator sc(kSectorSize, kSnapshotChunkSize);
+
+ if (operations == nullptr) return sc.cow_size_bytes();
+
+ for (const auto& iop : *operations) {
+ for (const auto& de : iop.dst_extents()) {
+ // Skip if no blocks are written
+ if (de.num_blocks() == 0) continue;
+
+ // Flag all the blocks that were written
+ const auto block_boundary = de.start_block() + de.num_blocks();
+ for (auto b = de.start_block(); b < block_boundary; ++b) {
+ for (unsigned int s = 0; s < sectors_per_block; ++s) {
+ const auto sector_id = b * sectors_per_block + s;
+ sc.WriteSector(sector_id);
+ }
+ }
+ }
+ }
+
+ return sc.cow_size_bytes();
}
std::optional<PartitionCowCreator::Return> PartitionCowCreator::Run() {
CHECK(current_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME &&
target_metadata->GetBlockDevicePartitionName(0) == LP_METADATA_DEFAULT_PARTITION_NAME);
- uint64_t logical_block_size = current_metadata->logical_block_size();
+ const uint64_t logical_block_size = current_metadata->logical_block_size();
CHECK(logical_block_size != 0 && !(logical_block_size & (logical_block_size - 1)))
<< "logical_block_size is not power of 2";
Return ret;
ret.snapshot_status.set_name(target_partition->name());
ret.snapshot_status.set_device_size(target_partition->size());
-
- // TODO(b/141889746): Optimize by using a smaller snapshot. Some ranges in target_partition
- // may be written directly.
ret.snapshot_status.set_snapshot_size(target_partition->size());
- auto cow_size = GetCowSize(ret.snapshot_status.snapshot_size());
- if (!cow_size.has_value()) return std::nullopt;
-
+ // Being the COW partition virtual, its size doesn't affect the storage
+ // memory that will be occupied by the target.
+ // The actual storage space is affected by the COW file, whose size depends
+ // on the chunks that diverged between |current| and |target|.
+ // If the |target| partition is bigger than |current|, the data that is
+ // modified outside of |current| can be written directly to |current|.
+ // This because the data that will be written outside of |current| would
+ // not invalidate any useful information of |current|, thus:
+ // - if the snapshot is accepted for merge, this data would be already at
+ // the right place and should not be copied;
+ // - in the unfortunate case of the snapshot to be discarded, the regions
+ // modified by this data can be set as free regions and reused.
// Compute regions that are free in both current and target metadata. These are the regions
// we can use for COW partition.
auto target_free_regions = target_metadata->GetFreeRegions();
@@ -102,13 +121,15 @@
auto free_regions = Interval::Intersect(target_free_regions, current_free_regions);
uint64_t free_region_length = 0;
for (const auto& interval : free_regions) {
- free_region_length += interval.length() * kSectorSize;
+ free_region_length += interval.length();
}
+ free_region_length *= kSectorSize;
LOG(INFO) << "Remaining free space for COW: " << free_region_length << " bytes";
+ auto cow_size = GetCowSize();
// Compute the COW partition size.
- uint64_t cow_partition_size = std::min(*cow_size, free_region_length);
+ uint64_t cow_partition_size = std::min(cow_size, free_region_length);
// Round it down to the nearest logical block. Logical partitions must be a multiple
// of logical blocks.
cow_partition_size &= ~(logical_block_size - 1);
@@ -116,8 +137,7 @@
// Assign cow_partition_usable_regions to indicate what regions should the COW partition uses.
ret.cow_partition_usable_regions = std::move(free_regions);
- // The rest of the COW space is allocated on ImageManager.
- uint64_t cow_file_size = (*cow_size) - ret.snapshot_status.cow_partition_size();
+ auto cow_file_size = cow_size - cow_partition_size;
// Round it up to the nearest sector.
cow_file_size += kSectorSize - 1;
cow_file_size &= ~(kSectorSize - 1);
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.h b/fs_mgr/libsnapshot/partition_cow_creator.h
index 8888f78..d3d186b 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.h
+++ b/fs_mgr/libsnapshot/partition_cow_creator.h
@@ -60,7 +60,7 @@
private:
bool HasExtent(Partition* p, Extent* e);
- std::optional<uint64_t> GetCowSize(uint64_t snapshot_size);
+ uint64_t GetCowSize();
};
} // namespace snapshot
diff --git a/fs_mgr/libsnapshot/partition_cow_creator_test.cpp b/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
index f683f5b..eae6c35 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
+++ b/fs_mgr/libsnapshot/partition_cow_creator_test.cpp
@@ -14,12 +14,14 @@
#include <gmock/gmock.h>
#include <gtest/gtest.h>
+#include <libdm/dm.h>
#include <liblp/builder.h>
#include <liblp/property_fetcher.h>
#include "dm_snapshot_internals.h"
#include "partition_cow_creator.h"
#include "test_helpers.h"
+#include "utility.h"
using namespace android::fs_mgr;
@@ -100,6 +102,90 @@
ASSERT_TRUE(ret.has_value());
}
+TEST_F(PartitionCowCreatorTest, CowSize) {
+ using InstallOperation = chromeos_update_engine::InstallOperation;
+ using RepeatedInstallOperationPtr = google::protobuf::RepeatedPtrField<InstallOperation>;
+ using Extent = chromeos_update_engine::Extent;
+
+ constexpr uint64_t initial_size = 50_MiB;
+ constexpr uint64_t final_size = 40_MiB;
+
+ auto builder_a = MetadataBuilder::New(initial_size, 1_KiB, 2);
+ ASSERT_NE(builder_a, nullptr);
+ auto system_a = builder_a->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
+ ASSERT_NE(system_a, nullptr);
+ ASSERT_TRUE(builder_a->ResizePartition(system_a, final_size));
+
+ auto builder_b = MetadataBuilder::New(initial_size, 1_KiB, 2);
+ ASSERT_NE(builder_b, nullptr);
+ auto system_b = builder_b->AddPartition("system_b", LP_PARTITION_ATTR_READONLY);
+ ASSERT_NE(system_b, nullptr);
+ ASSERT_TRUE(builder_b->ResizePartition(system_b, final_size));
+
+ const uint64_t block_size = builder_b->logical_block_size();
+ const uint64_t chunk_size = kSnapshotChunkSize * dm::kSectorSize;
+ ASSERT_EQ(chunk_size, block_size);
+
+ auto cow_device_size = [](const std::vector<InstallOperation>& iopv, MetadataBuilder* builder_a,
+ MetadataBuilder* builder_b, Partition* system_b) {
+ RepeatedInstallOperationPtr riop(iopv.begin(), iopv.end());
+ PartitionCowCreator creator{.target_metadata = builder_b,
+ .target_suffix = "_b",
+ .target_partition = system_b,
+ .current_metadata = builder_a,
+ .current_suffix = "_a",
+ .operations = &riop};
+
+ auto ret = creator.Run();
+
+ if (ret.has_value()) {
+ return ret->snapshot_status.cow_file_size() + ret->snapshot_status.cow_partition_size();
+ }
+ return std::numeric_limits<uint64_t>::max();
+ };
+
+ std::vector<InstallOperation> iopv;
+ InstallOperation iop;
+ Extent* e;
+
+ // No data written, no operations performed
+ ASSERT_EQ(2 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+
+ // No data written
+ e = iop.add_dst_extents();
+ e->set_start_block(0);
+ e->set_num_blocks(0);
+ iopv.push_back(iop);
+ ASSERT_EQ(2 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+
+ e = iop.add_dst_extents();
+ e->set_start_block(1);
+ e->set_num_blocks(0);
+ iopv.push_back(iop);
+ ASSERT_EQ(2 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+
+ // Fill the first block
+ e = iop.add_dst_extents();
+ e->set_start_block(0);
+ e->set_num_blocks(1);
+ iopv.push_back(iop);
+ ASSERT_EQ(3 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+
+ // Fill the second block
+ e = iop.add_dst_extents();
+ e->set_start_block(1);
+ e->set_num_blocks(1);
+ iopv.push_back(iop);
+ ASSERT_EQ(4 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+
+ // Jump to 5th block and write 2
+ e = iop.add_dst_extents();
+ e->set_start_block(5);
+ e->set_num_blocks(2);
+ iopv.push_back(iop);
+ ASSERT_EQ(6 * chunk_size, cow_device_size(iopv, builder_a.get(), builder_b.get(), system_b));
+}
+
TEST(DmSnapshotInternals, CowSizeCalculator) {
DmSnapCowSizeCalculator cc(512, 8);
unsigned long int b;
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 2161e5b..5728582 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -784,9 +784,17 @@
}
// Grow all partitions.
- SetSize(sys_, 3788_KiB);
- SetSize(vnd_, 3788_KiB);
- SetSize(prd_, 3788_KiB);
+ constexpr uint64_t partition_size = 3788_KiB;
+ SetSize(sys_, partition_size);
+ SetSize(vnd_, partition_size);
+ SetSize(prd_, partition_size);
+
+ // Create fake install operations to grow the COW device size.
+ for (auto& partition : {sys_, vnd_, prd_}) {
+ auto e = partition->add_operations()->add_dst_extents();
+ e->set_start_block(0);
+ e->set_num_blocks(GetSize(partition) / manifest_.block_size());
+ }
// Execute the update.
ASSERT_TRUE(sm->BeginUpdate());
@@ -949,6 +957,13 @@
ASSERT_TRUE(sm->BeginUpdate());
ASSERT_TRUE(sm->UnmapUpdateSnapshot("sys_b"));
+ // Create fake install operations to grow the COW device size.
+ for (auto& partition : {sys_, vnd_, prd_}) {
+ auto e = partition->add_operations()->add_dst_extents();
+ e->set_start_block(0);
+ e->set_num_blocks(GetSize(partition) / manifest_.block_size());
+ }
+
ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
// Write some data to target partitions.
diff --git a/fs_mgr/libsnapshot/test_helpers.cpp b/fs_mgr/libsnapshot/test_helpers.cpp
index 539c5c5..312fa3e 100644
--- a/fs_mgr/libsnapshot/test_helpers.cpp
+++ b/fs_mgr/libsnapshot/test_helpers.cpp
@@ -140,5 +140,9 @@
partition_update->mutable_new_partition_info()->set_size(size);
}
+uint64_t GetSize(PartitionUpdate* partition_update) {
+ return partition_update->mutable_new_partition_info()->size();
+}
+
} // namespace snapshot
} // namespace android
diff --git a/fs_mgr/libsnapshot/test_helpers.h b/fs_mgr/libsnapshot/test_helpers.h
index 5fe701f..0f70afe 100644
--- a/fs_mgr/libsnapshot/test_helpers.h
+++ b/fs_mgr/libsnapshot/test_helpers.h
@@ -141,5 +141,8 @@
// In the update package metadata, set a partition with the given size.
void SetSize(PartitionUpdate* partition_update, uint64_t size);
+// Get partition size from update package metadata.
+uint64_t GetSize(PartitionUpdate* partition_update);
+
} // namespace snapshot
} // namespace android