diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index e9409c460acd0..912903de4de42 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -4794,15 +4794,17 @@ void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
 }
 
 /*
- * wait for all write mds requests to flush.
+ * flush the mdlog and wait for all write mds requests to flush.
  */
-static void wait_unsafe_requests(struct ceph_mds_client *mdsc, u64 want_tid)
+static void flush_mdlog_and_wait_mdsc_unsafe_requests(struct ceph_mds_client *mdsc,
+						 u64 want_tid)
 {
 	struct ceph_mds_request *req = NULL, *nextreq;
+	struct ceph_mds_session *last_session = NULL;
 	struct rb_node *n;
 
 	mutex_lock(&mdsc->mutex);
-	dout("wait_unsafe_requests want %lld\n", want_tid);
+	dout("%s want %lld\n", __func__, want_tid);
 restart:
 	req = __get_oldest_req(mdsc);
 	while (req && req->r_tid <= want_tid) {
@@ -4814,14 +4816,32 @@ static void wait_unsafe_requests(struct ceph_mds_client *mdsc, u64 want_tid)
 			nextreq = NULL;
 		if (req->r_op != CEPH_MDS_OP_SETFILELOCK &&
 		    (req->r_op & CEPH_MDS_OP_WRITE)) {
+			struct ceph_mds_session *s = req->r_session;
+
+			if (!s) {
+				req = nextreq;
+				continue;
+			}
+
 			/* write op */
 			ceph_mdsc_get_request(req);
 			if (nextreq)
 				ceph_mdsc_get_request(nextreq);
+			s = ceph_get_mds_session(s);
 			mutex_unlock(&mdsc->mutex);
-			dout("wait_unsafe_requests  wait on %llu (want %llu)\n",
+
+			/* send flush mdlog request to MDS */
+			if (last_session != s) {
+				send_flush_mdlog(s);
+				ceph_put_mds_session(last_session);
+				last_session = s;
+			} else {
+				ceph_put_mds_session(s);
+			}
+			dout("%s wait on %llu (want %llu)\n", __func__,
 			     req->r_tid, want_tid);
 			wait_for_completion(&req->r_safe_completion);
+
 			mutex_lock(&mdsc->mutex);
 			ceph_mdsc_put_request(req);
 			if (!nextreq)
@@ -4836,7 +4856,8 @@ static void wait_unsafe_requests(struct ceph_mds_client *mdsc, u64 want_tid)
 		req = nextreq;
 	}
 	mutex_unlock(&mdsc->mutex);
-	dout("wait_unsafe_requests done\n");
+	ceph_put_mds_session(last_session);
+	dout("%s done\n", __func__);
 }
 
 void ceph_mdsc_sync(struct ceph_mds_client *mdsc)
@@ -4865,7 +4886,7 @@ void ceph_mdsc_sync(struct ceph_mds_client *mdsc)
 	dout("sync want tid %lld flush_seq %lld\n",
 	     want_tid, want_flush);
 
-	wait_unsafe_requests(mdsc, want_tid);
+	flush_mdlog_and_wait_mdsc_unsafe_requests(mdsc, want_tid);
 	wait_caps_flush(mdsc, want_flush);
 }