From: Sage Weil <sage@redhat.com>
Date: Wed, 12 Apr 2017 18:19:46 +0000 (-0400)
Subject: os/bluestore: fix narrow osr->flush() race
X-Git-Tag: v12.0.2~68^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F14489%2Fhead;p=ceph.git

os/bluestore: fix narrow osr->flush() race

Signed-off-by: Sage Weil <sage@redhat.com>
---

diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 8c7732fa8378..535c745ae53c 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -1655,10 +1655,13 @@ public:
     void flush() override {
       std::unique_lock<std::mutex> l(qlock);
       while (true) {
+	// set flag before the check because the condition
+	// may become true outside qlock, and we need to make
+	// sure those threads see waiters and signal qcond.
+	++kv_submitted_waiters;
 	if (_is_all_kv_submitted()) {
 	  return;
 	}
-	++kv_submitted_waiters;
 	qcond.wait(l);
 	--kv_submitted_waiters;
       }