Revert enabling IO uring in db_stress (facebook#11242)

Summary:
IO uring usage is causing crash test failures due to bad cqe data being returned in the uring. Revert the change to enable IO uring in db_stress, and also re-enable async_io in CircleCI so that code path can be tested. Added the -use_io_uring flag to db_stress that, when false, will wrap the default env in db_stress to emulate async IO.

Pull Request resolved: facebook#11242

Reviewed By: akankshamahajan15

Differential Revision: D43470569

Pulled By: anand1976

fbshipit-source-id: 7c69ac3f53a79ade31d37313f815f1a4b6108b75

Author: anand1976

.circleci/config.yml

@@ -516,7 +516,7 @@ jobs:
     resource_class: large
     steps:
       - pre-steps
-      - run: ulimit -S -n `ulimit -H -n` && make V=1 -j8 CRASH_TEST_EXT_ARGS='--duration=960 --max_key=2500000 --async_io=0' blackbox_crash_test_with_atomic_flush
+      - run: ulimit -S -n `ulimit -H -n` && make V=1 -j8 CRASH_TEST_EXT_ARGS='--duration=960 --max_key=2500000 --use_io_uring=0' blackbox_crash_test_with_atomic_flush
       - post-steps
 
   build-linux-crashtest-tiered-storage-bb:
@@ -526,7 +526,7 @@ jobs:
       - pre-steps
       - run:
           name: "run crashtest"
-          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --async_io=0' blackbox_crash_test_with_tiered_storage
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --use_io_uring=0' blackbox_crash_test_with_tiered_storage
           no_output_timeout: 100m
       - post-steps
 
@@ -537,7 +537,7 @@ jobs:
       - pre-steps
       - run:
           name: "run crashtest"
-          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --async_io=0' whitebox_crash_test_with_tiered_storage
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS='--duration=10800 --use_io_uring=0' whitebox_crash_test_with_tiered_storage
           no_output_timeout: 100m
       - post-steps
 

db_stress_tool/db_stress_common.h

@@ -321,6 +321,7 @@ DECLARE_uint64(readahead_size);
 DECLARE_uint64(initial_auto_readahead_size);
 DECLARE_uint64(max_auto_readahead_size);
 DECLARE_uint64(num_file_reads_for_auto_readahead);
+DECLARE_bool(use_io_uring);
 
 constexpr long KB = 1024;
 constexpr int kRandomValueMaxFactor = 3;

db_stress_tool/db_stress_gflags.cc

@@ -1073,6 +1073,7 @@ DEFINE_uint64(stats_dump_period_sec,
               ROCKSDB_NAMESPACE::Options().stats_dump_period_sec,
               "Gap between printing stats to log in seconds");
 
-extern "C" bool RocksDbIOUringEnable() { return true; }
+DEFINE_bool(use_io_uring, false, "Enable the use of IO uring on Posix");
+extern "C" bool RocksDbIOUringEnable() { return FLAGS_use_io_uring; }
 
 #endif  // GFLAGS

db_stress_tool/db_stress_tool.cc

@@ -99,6 +99,13 @@ int db_stress_tool(int argc, char** argv) {
 
   env_wrapper_guard = std::make_shared<CompositeEnvWrapper>(
       raw_env, std::make_shared<DbStressFSWrapper>(raw_env->GetFileSystem()));
+  if (!env_opts && !FLAGS_use_io_uring) {
+    // If using the default Env (Posix), wrap DbStressEnvWrapper with the
+    // legacy EnvWrapper. This is a workaround to prevent MultiGet and scans
+    // from failing when IO uring is disabled. The EnvWrapper
+    // has a default implementation of ReadAsync that redirects to Read.
+    env_wrapper_guard = std::make_shared<EnvWrapper>(env_wrapper_guard);
+  }
   db_stress_env = env_wrapper_guard.get();
 
   FLAGS_rep_factory = StringToRepFactory(FLAGS_memtablerep.c_str());