diff --git a/fs_mgr/libsnapshot/snapuserd/cow_snapuserd_test.cpp b/fs_mgr/libsnapshot/snapuserd/cow_snapuserd_test.cpp index f4aef4468..bff0a50c8 100644 --- a/fs_mgr/libsnapshot/snapuserd/cow_snapuserd_test.cpp +++ b/fs_mgr/libsnapshot/snapuserd/cow_snapuserd_test.cpp @@ -108,6 +108,7 @@ class CowSnapuserdTest final { void MergeInterruptFixed(int duration); void MergeInterruptRandomly(int max_duration); void ReadDmUserBlockWithoutDaemon(); + void ReadLastBlock(); std::string snapshot_dev() const { return snapshot_dev_->path(); } @@ -256,6 +257,73 @@ void CowSnapuserdTest::StartSnapuserdDaemon() { } } +void CowSnapuserdTest::ReadLastBlock() { + unique_fd rnd_fd; + total_base_size_ = BLOCK_SZ * 2; + + base_fd_ = CreateTempFile("base_device", total_base_size_); + ASSERT_GE(base_fd_, 0); + + rnd_fd.reset(open("/dev/random", O_RDONLY)); + ASSERT_TRUE(rnd_fd > 0); + + std::unique_ptr random_buffer = std::make_unique(BLOCK_SZ); + + for (size_t j = 0; j < ((total_base_size_) / BLOCK_SZ); j++) { + ASSERT_EQ(ReadFullyAtOffset(rnd_fd, (char*)random_buffer.get(), BLOCK_SZ, 0), true); + ASSERT_EQ(android::base::WriteFully(base_fd_, random_buffer.get(), BLOCK_SZ), true); + } + + ASSERT_EQ(lseek(base_fd_, 0, SEEK_SET), 0); + + base_loop_ = std::make_unique(base_fd_, 10s); + ASSERT_TRUE(base_loop_->valid()); + + std::string path = android::base::GetExecutableDirectory(); + cow_system_ = std::make_unique(path); + + std::unique_ptr random_buffer_1_ = std::make_unique(total_base_size_); + loff_t offset = 0; + + // Fill random data + for (size_t j = 0; j < (total_base_size_ / BLOCK_SZ); j++) { + ASSERT_EQ(ReadFullyAtOffset(rnd_fd, (char*)random_buffer_1_.get() + offset, BLOCK_SZ, 0), + true); + + offset += BLOCK_SZ; + } + + CowOptions options; + options.compression = "gz"; + CowWriter writer(options); + + ASSERT_TRUE(writer.Initialize(cow_system_->fd)); + + ASSERT_TRUE(writer.AddRawBlocks(0, random_buffer_1_.get(), BLOCK_SZ)); + ASSERT_TRUE(writer.AddRawBlocks(1, (char*)random_buffer_1_.get() + BLOCK_SZ, BLOCK_SZ)); + + ASSERT_TRUE(writer.Finalize()); + + SetDeviceControlName(); + + StartSnapuserdDaemon(); + InitCowDevice(); + + CreateDmUserDevice(); + InitDaemon(); + + CreateSnapshotDevice(); + + unique_fd snapshot_fd(open(snapshot_dev_->path().c_str(), O_RDONLY)); + ASSERT_TRUE(snapshot_fd > 0); + + std::unique_ptr snapuserd_buffer = std::make_unique(BLOCK_SZ); + + offset = 7680; + ASSERT_EQ(ReadFullyAtOffset(snapshot_fd, snapuserd_buffer.get(), 512, offset), true); + ASSERT_EQ(memcmp(snapuserd_buffer.get(), (char*)random_buffer_1_.get() + offset, 512), 0); +} + void CowSnapuserdTest::CreateBaseDevice() { unique_fd rnd_fd; @@ -1143,6 +1211,12 @@ TEST(Snapuserd_Test, Snapshot_IO_TEST) { harness.Shutdown(); } +TEST(Snapuserd_Test, Snapshot_END_IO_TEST) { + CowSnapuserdTest harness; + harness.ReadLastBlock(); + harness.Shutdown(); +} + TEST(Snapuserd_Test, Snapshot_COPY_Overlap_TEST_1) { CowSnapuserdTest harness; ASSERT_TRUE(harness.SetupCopyOverlap_1()); diff --git a/fs_mgr/libsnapshot/snapuserd/snapuserd_worker.cpp b/fs_mgr/libsnapshot/snapuserd/snapuserd_worker.cpp index cdf9fe718..5d184adf6 100644 --- a/fs_mgr/libsnapshot/snapuserd/snapuserd_worker.cpp +++ b/fs_mgr/libsnapshot/snapuserd/snapuserd_worker.cpp @@ -350,16 +350,36 @@ int WorkerThread::ReadData(sector_t sector, size_t size) { it = std::lower_bound(chunk_vec.begin(), chunk_vec.end(), std::make_pair(sector, nullptr), Snapuserd::compare); - if (!(it != chunk_vec.end())) { - SNAP_LOG(ERROR) << "ReadData: Sector " << sector << " not found in chunk_vec"; - return -1; + bool read_end_of_device = false; + if (it == chunk_vec.end()) { + // |-------|-------|-------| + // 0 1 2 3 + // + // Block 0 - op 1 + // Block 1 - op 2 + // Block 2 - op 3 + // + // chunk_vec will have block 0, 1, 2 which maps to relavant COW ops. + // + // Each block is 4k bytes. Thus, the last block will span 8 sectors + // ranging till block 3 (However, block 3 won't be in chunk_vec as + // it doesn't have any mapping to COW ops. Now, if we get an I/O request for a sector + // spanning between block 2 and block 3, we need to step back + // and get hold of the last element. + // + // Additionally, dm-snapshot makes sure that I/O request beyond block 3 + // will not be routed to the daemon. Hence, it is safe to assume that + // if a sector is not available in the chunk_vec, the I/O falls in the + // end of region. + it = std::prev(chunk_vec.end()); + read_end_of_device = true; } // We didn't find the required sector; hence find the previous sector // as lower_bound will gives us the value greater than // the requested sector if (it->first != sector) { - if (it != chunk_vec.begin()) { + if (it != chunk_vec.begin() && !read_end_of_device) { --it; }