FlushMemTable return ok but memtable does not synchronize flush (#8173)

Summary:
Fix #8046 : FlushMemTable return ok but memtable does not synchronize flush. The way to fix it is to expose RecoveryError.

Pull Request resolved: #8173

Reviewed By: ajkr

Differential Revision: D31674552

Pulled By: jay-zhuang

fbshipit-source-id: 9d16b69ba12a196bb429332ec8224754de97773d

HISTORY.md

@@ -9,6 +9,9 @@
 ### Behavior Changes
 * `DB::DestroyColumnFamilyHandle()` will return Status::InvalidArgument() if called with `DB::DefaultColumnFamily()`.
 
+### Bug Fixes
+* Fix a bug that FlushMemTable may return ok even flush not succeed.
+
 ## 6.28.0 (2021-12-17)
 ### New Features
 * Introduced 'CommitWithTimestamp' as a new tag. Currently, there is no API for user to trigger a write with this tag to the WAL. This is part of the efforts to support write-commited transactions with user-defined timestamps.

db/db_impl/db_impl_compaction_flush.cc

@@ -2264,21 +2264,27 @@ Status DBImpl::WaitForFlushMemTables(
   int num = static_cast<int>(cfds.size());
   // Wait until the compaction completes
   InstrumentedMutexLock l(&mutex_);
+  Status s;
   // If the caller is trying to resume from bg error, then
   // error_handler_.IsDBStopped() is true.
   while (resuming_from_bg_err || !error_handler_.IsDBStopped()) {
     if (shutting_down_.load(std::memory_order_acquire)) {
-      return Status::ShutdownInProgress();
+      s = Status::ShutdownInProgress();
+      return s;
     }
     // If an error has occurred during resumption, then no need to wait.
+    // But flush operation may fail because of this error, so need to
+    // return the status.
     if (!error_handler_.GetRecoveryError().ok()) {
+      s = error_handler_.GetRecoveryError();
       break;
     }
     // If BGWorkStopped, which indicate that there is a BG error and
     // 1) soft error but requires no BG work, 2) no in auto_recovery_
     if (!resuming_from_bg_err && error_handler_.IsBGWorkStopped() &&
         error_handler_.GetBGError().severity() < Status::Severity::kHardError) {
-      return error_handler_.GetBGError();
+      s = error_handler_.GetBGError();
+      return s;
     }
 
     // Number of column families that have been dropped.
@@ -2296,7 +2302,8 @@ Status DBImpl::WaitForFlushMemTables(
       }
     }
     if (1 == num_dropped && 1 == num) {
-      return Status::ColumnFamilyDropped();
+      s = Status::ColumnFamilyDropped();
+      return s;
     }
     // Column families involved in this flush request have either been dropped
     // or finished flush. Then it's time to finish waiting.
@@ -2305,7 +2312,6 @@ Status DBImpl::WaitForFlushMemTables(
     }
     bg_cv_.Wait();
   }
-  Status s;
   // If not resuming from bg error, and an error has caused the DB to stop,
   // then report the bg error to caller.
   if (!resuming_from_bg_err && error_handler_.IsDBStopped()) {