From: Jason Dillaman <dillaman@redhat.com>
Date: Mon, 9 Nov 2015 16:22:24 +0000 (-0500)
Subject: librbd: fixed deadlock while attempting to flush AIO requests
X-Git-Tag: v0.94.6~60^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F6586%2Fhead;p=ceph.git

librbd: fixed deadlock while attempting to flush AIO requests

In-flight AIO requests might force a flush if a snapshot was created
out-of-band.  The flush completion was previously invoked asynchronously,
potentially via the same thread worker handling the AIO request. This
resulted in the flush operation deadlocking since it can't complete.

Fixes: #13726
Backport: infernalis, hammer
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit bfeb90e5fe24347648c72345881fd3d932243c98)
---

diff --git a/src/librbd/ImageCtx.cc b/src/librbd/ImageCtx.cc
index 0f5d46a56f46..1574c56896fb 100644
--- a/src/librbd/ImageCtx.cc
+++ b/src/librbd/ImageCtx.cc
@@ -807,7 +807,7 @@ public:
   void ImageCtx::flush_async_operations(Context *on_finish) {
     Mutex::Locker l(async_ops_lock);
     if (async_ops.empty()) {
-      op_work_queue->queue(on_finish, 0);
+      on_finish->complete(0);
       return;
     }