1 files changed, 31 insertions, 45 deletions

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 70286737eb0a..e1a0df67b566 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -148,6 +148,8 @@
 /* 5 seconds wait to sync ending of dlm */
 #define DLM_SHUTDOWN_TIMEOUT	msecs_to_jiffies(5000)
 #define DLM_VERSION_NOT_SET	0
+#define DLM_SEND_ACK_BACK_MSG_THRESHOLD 32
+#define DLM_RECV_ACK_BACK_MSG_THRESHOLD (DLM_SEND_ACK_BACK_MSG_THRESHOLD * 8)
 
 struct midcomms_node {
 	int nodeid;
@@ -165,7 +167,7 @@ struct midcomms_node {
 #define DLM_NODE_FLAG_CLOSE	1
 #define DLM_NODE_FLAG_STOP_TX	2
 #define DLM_NODE_FLAG_STOP_RX	3
-#define DLM_NODE_ULP_DELIVERED	4
+	atomic_t ulp_delivered;
 	unsigned long flags;
 	wait_queue_head_t shutdown_wait;
 
@@ -319,6 +321,7 @@ static void midcomms_node_reset(struct midcomms_node *node)
 
 	atomic_set(&node->seq_next, DLM_SEQ_INIT);
 	atomic_set(&node->seq_send, DLM_SEQ_INIT);
+	atomic_set(&node->ulp_delivered, 0);
 	node->version = DLM_VERSION_NOT_SET;
 	node->flags = 0;
 
@@ -393,6 +396,28 @@ static int dlm_send_ack(int nodeid, uint32_t seq)
 	return 0;
 }
 
+static void dlm_send_ack_threshold(struct midcomms_node *node,
+				   uint32_t threshold)
+{
+	uint32_t oval, nval;
+	bool send_ack;
+
+	/* let only send one user trigger threshold to send ack back */
+	do {
+		oval = atomic_read(&node->ulp_delivered);
+		send_ack = (oval > threshold);
+		/* abort if threshold is not reached */
+		if (!send_ack)
+			break;
+
+		nval = 0;
+		/* try to reset ulp_delivered counter */
+	} while (atomic_cmpxchg(&node->ulp_delivered, oval, nval) != oval);
+
+	if (send_ack)
+		dlm_send_ack(node->nodeid, atomic_read(&node->seq_next));
+}
+
 static int dlm_send_fin(struct midcomms_node *node,
 			void (*ack_rcv)(struct midcomms_node *node))
 {
@@ -560,7 +585,9 @@ static void dlm_midcomms_receive_buffer(union dlm_packet *p,
 			WARN_ON_ONCE(test_bit(DLM_NODE_FLAG_STOP_RX, &node->flags));
 			dlm_receive_buffer_3_2_trace(seq, p);
 			dlm_receive_buffer(p, node->nodeid);
-			set_bit(DLM_NODE_ULP_DELIVERED, &node->flags);
+			atomic_inc(&node->ulp_delivered);
+			/* unlikely case to send ack back when we don't transmit */
+			dlm_send_ack_threshold(node, DLM_RECV_ACK_BACK_MSG_THRESHOLD);
 			break;
 		}
 	} else {
@@ -969,49 +996,6 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 	return ret;
 }
 
-void dlm_midcomms_receive_done(int nodeid)
-{
-	struct midcomms_node *node;
-	int idx;
-
-	idx = srcu_read_lock(&nodes_srcu);
-	node = nodeid2node(nodeid, 0);
-	if (!node) {
-		srcu_read_unlock(&nodes_srcu, idx);
-		return;
-	}
-
-	/* old protocol, we do nothing */
-	switch (node->version) {
-	case DLM_VERSION_3_2:
-		break;
-	default:
-		srcu_read_unlock(&nodes_srcu, idx);
-		return;
-	}
-
-	/* do nothing if we didn't delivered stateful to ulp */
-	if (!test_and_clear_bit(DLM_NODE_ULP_DELIVERED,
-				&node->flags)) {
-		srcu_read_unlock(&nodes_srcu, idx);
-		return;
-	}
-
-	spin_lock(&node->state_lock);
-	/* we only ack if state is ESTABLISHED */
-	switch (node->state) {
-	case DLM_ESTABLISHED:
-		spin_unlock(&node->state_lock);
-		dlm_send_ack(node->nodeid, atomic_read(&node->seq_next));
-		break;
-	default:
-		spin_unlock(&node->state_lock);
-		/* do nothing FIN has it's own ack send */
-		break;
-	}
-	srcu_read_unlock(&nodes_srcu, idx);
-}
-
 void dlm_midcomms_unack_msg_resend(int nodeid)
 {
 	struct midcomms_node *node;
@@ -1142,6 +1126,8 @@ struct dlm_mhandle *dlm_midcomms_get_mhandle(int nodeid, int len,
 			goto err;
 		}
 
+		/* send ack back if necessary */
+		dlm_send_ack_threshold(node, DLM_SEND_ACK_BACK_MSG_THRESHOLD);
 		break;
 	default:
 		dlm_free_mhandle(mh);