librbd: flush journal commit positions before starting op

Ensure all IO has been properly flushed and committed to the
journal before starting an op that could affect the IO path.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/src/librbd/Journal.cc b/src/librbd/Journal.cc
index 8e59356afbf956f6a9e5a36e037b171f790d39a9..b24e8611e0bb48f2d3018c359ba2ec75f293682a 100644 (file)
--- a/src/librbd/Journal.cc
+++ b/src/librbd/Journal.cc
@@ -965,6 +965,10 @@ void Journal<I>::append_op_event(uint64_t op_tid,
   }
 
   on_safe = create_async_context_callback(m_image_ctx, on_safe);
+  on_safe = new FunctionContext([this, on_safe](int r) {
+      // ensure all committed IO before this op is committed
+      m_journaler->flush_commit_position(on_safe);
+    });
   future.flush(on_safe);
 
   CephContext *cct = m_image_ctx.cct;