From: Jason Dillaman <dillaman@redhat.com>
Date: Tue, 8 Dec 2020 14:58:07 +0000 (-0500)
Subject: librbd/io: flush IO before shutting down image IO dispatchers
X-Git-Tag: v16.1.0~299^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F38492%2Fhead;p=ceph.git

librbd/io: flush IO before shutting down image IO dispatchers

Otherwise, if the dispatchers are shut down, there is a potential
race where the flush can be assigned to a stuck IO and never
completed.

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

diff --git a/src/librbd/io/ImageDispatcher.cc b/src/librbd/io/ImageDispatcher.cc
index a9c1c985522..fa0cc77703d 100644
--- a/src/librbd/io/ImageDispatcher.cc
+++ b/src/librbd/io/ImageDispatcher.cc
@@ -217,11 +217,11 @@ void ImageDispatcher<I>::shut_down(Context* on_finish) {
       delete async_op;
       on_finish->complete(0);
     });
-  on_finish = new LambdaContext([this, async_op, on_finish](int r) {
-      async_op->start_op(*this->m_image_ctx);
-      async_op->flush(on_finish);
+  on_finish = new LambdaContext([this, on_finish](int r) {
+      Dispatcher<I, ImageDispatcherInterface>::shut_down(on_finish);
     });
-  Dispatcher<I, ImageDispatcherInterface>::shut_down(on_finish);
+  async_op->start_op(*this->m_image_ctx);
+  async_op->flush(on_finish);
 }
 
 template <typename I>