1 files changed, 52 insertions, 23 deletions

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 15810701b13e..7c7a31377f27 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -113,6 +113,7 @@ struct writequeue_entry {
 	int len;
 	int end;
 	int users;
+	int idx; /* get()/commit() idx exchange */
 	struct connection *con;
 };
 
@@ -163,21 +164,14 @@ static inline int nodeid_hash(int nodeid)
 	return nodeid & (CONN_HASH_SIZE-1);
 }
 
-static struct connection *__find_con(int nodeid)
+static struct connection *__find_con(int nodeid, int r)
 {
-	int r, idx;
 	struct connection *con;
 
-	r = nodeid_hash(nodeid);
-
-	idx = srcu_read_lock(&connections_srcu);
 	hlist_for_each_entry_rcu(con, &connection_hash[r], list) {
-		if (con->nodeid == nodeid) {
-			srcu_read_unlock(&connections_srcu, idx);
+		if (con->nodeid == nodeid)
 			return con;
-		}
 	}
-	srcu_read_unlock(&connections_srcu, idx);
 
 	return NULL;
 }
@@ -216,7 +210,8 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 	struct connection *con, *tmp;
 	int r, ret;
 
-	con = __find_con(nodeid);
+	r = nodeid_hash(nodeid);
+	con = __find_con(nodeid, r);
 	if (con || !alloc)
 		return con;
 
@@ -230,8 +225,6 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 		return NULL;
 	}
 
-	r = nodeid_hash(nodeid);
-
 	spin_lock(&connections_lock);
 	/* Because multiple workqueues/threads calls this function it can
 	 * race on multiple cpu's. Instead of locking hot path __find_con()
@@ -239,7 +232,7 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 	 * under protection of connections_lock. If this is the case we
 	 * abort our connection creation and return the existing connection.
 	 */
-	tmp = __find_con(nodeid);
+	tmp = __find_con(nodeid, r);
 	if (tmp) {
 		spin_unlock(&connections_lock);
 		kfree(con->rx_buf);
@@ -256,15 +249,13 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 /* Loop round all connections */
 static void foreach_conn(void (*conn_func)(struct connection *c))
 {
-	int i, idx;
+	int i;
 	struct connection *con;
 
-	idx = srcu_read_lock(&connections_srcu);
 	for (i = 0; i < CONN_HASH_SIZE; i++) {
 		hlist_for_each_entry_rcu(con, &connection_hash[i], list)
 			conn_func(con);
 	}
-	srcu_read_unlock(&connections_srcu, idx);
 }
 
 static struct dlm_node_addr *find_node_addr(int nodeid)
@@ -518,14 +509,21 @@ static void lowcomms_state_change(struct sock *sk)
 int dlm_lowcomms_connect_node(int nodeid)
 {
 	struct connection *con;
+	int idx;
 
 	if (nodeid == dlm_our_nodeid())
 		return 0;
 
+	idx = srcu_read_lock(&connections_srcu);
 	con = nodeid2con(nodeid, GFP_NOFS);
-	if (!con)
+	if (!con) {
+		srcu_read_unlock(&connections_srcu, idx);
 		return -ENOMEM;
+	}
+
 	lowcomms_connect_sock(con);
+	srcu_read_unlock(&connections_srcu, idx);
+
 	return 0;
 }
 
@@ -864,7 +862,7 @@ static int accept_from_sock(struct listen_connection *con)
 	int result;
 	struct sockaddr_storage peeraddr;
 	struct socket *newsock;
-	int len;
+	int len, idx;
 	int nodeid;
 	struct connection *newcon;
 	struct connection *addcon;
@@ -907,8 +905,10 @@ static int accept_from_sock(struct listen_connection *con)
 	 *  the same time and the connections cross on the wire.
 	 *  In this case we store the incoming one in "othercon"
 	 */
+	idx = srcu_read_lock(&connections_srcu);
 	newcon = nodeid2con(nodeid, GFP_NOFS);
 	if (!newcon) {
+		srcu_read_unlock(&connections_srcu, idx);
 		result = -ENOMEM;
 		goto accept_err;
 	}
@@ -924,6 +924,7 @@ static int accept_from_sock(struct listen_connection *con)
 			if (!othercon) {
 				log_print("failed to allocate incoming socket");
 				mutex_unlock(&newcon->sock_mutex);
+				srcu_read_unlock(&connections_srcu, idx);
 				result = -ENOMEM;
 				goto accept_err;
 			}
@@ -932,6 +933,7 @@ static int accept_from_sock(struct listen_connection *con)
 			if (result < 0) {
 				kfree(othercon);
 				mutex_unlock(&newcon->sock_mutex);
+				srcu_read_unlock(&connections_srcu, idx);
 				goto accept_err;
 			}
 
@@ -966,6 +968,8 @@ static int accept_from_sock(struct listen_connection *con)
 	if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
 		queue_work(recv_workqueue, &addcon->rwork);
 
+	srcu_read_unlock(&connections_srcu, idx);
+
 	return 0;
 
 accept_err:
@@ -1403,7 +1407,9 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 
 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 {
+	struct writequeue_entry *e;
 	struct connection *con;
+	int idx;
 
 	if (len > DEFAULT_BUFFER_SIZE ||
 	    len < sizeof(struct dlm_header)) {
@@ -1413,11 +1419,23 @@ void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 		return NULL;
 	}
 
+	idx = srcu_read_lock(&connections_srcu);
 	con = nodeid2con(nodeid, allocation);
-	if (!con)
+	if (!con) {
+		srcu_read_unlock(&connections_srcu, idx);
 		return NULL;
+	}
+
+	e = new_wq_entry(con, len, allocation, ppc);
+	if (!e) {
+		srcu_read_unlock(&connections_srcu, idx);
+		return NULL;
+	}
+
+	/* we assume if successful commit must called */
+	e->idx = idx;
 
-	return new_wq_entry(con, len, allocation, ppc);
+	return e;
 }
 
 void dlm_lowcomms_commit_buffer(void *mh)
@@ -1435,10 +1453,12 @@ void dlm_lowcomms_commit_buffer(void *mh)
 	spin_unlock(&con->writequeue_lock);
 
 	queue_work(send_workqueue, &con->swork);
+	srcu_read_unlock(&connections_srcu, e->idx);
 	return;
 
 out:
 	spin_unlock(&con->writequeue_lock);
+	srcu_read_unlock(&connections_srcu, e->idx);
 	return;
 }
 
@@ -1532,8 +1552,10 @@ int dlm_lowcomms_close(int nodeid)
 {
 	struct connection *con;
 	struct dlm_node_addr *na;
+	int idx;
 
 	log_print("closing connection to node %d", nodeid);
+	idx = srcu_read_lock(&connections_srcu);
 	con = nodeid2con(nodeid, 0);
 	if (con) {
 		set_bit(CF_CLOSE, &con->flags);
@@ -1542,6 +1564,7 @@ int dlm_lowcomms_close(int nodeid)
 		if (con->othercon)
 			clean_one_writequeue(con->othercon);
 	}
+	srcu_read_unlock(&connections_srcu, idx);
 
 	spin_lock(&dlm_node_addrs_spin);
 	na = find_node_addr(nodeid);
@@ -1621,6 +1644,8 @@ static void shutdown_conn(struct connection *con)
 
 void dlm_lowcomms_shutdown(void)
 {
+	int idx;
+
 	/* Set all the flags to prevent any
 	 * socket activity.
 	 */
@@ -1633,7 +1658,9 @@ void dlm_lowcomms_shutdown(void)
 
 	dlm_close_sock(&listen_con.sock);
 
+	idx = srcu_read_lock(&connections_srcu);
 	foreach_conn(shutdown_conn);
+	srcu_read_unlock(&connections_srcu, idx);
 }
 
 static void _stop_conn(struct connection *con, bool and_other)
@@ -1682,7 +1709,7 @@ static void free_conn(struct connection *con)
 
 static void work_flush(void)
 {
-	int ok, idx;
+	int ok;
 	int i;
 	struct connection *con;
 
@@ -1693,7 +1720,6 @@ static void work_flush(void)
 			flush_workqueue(recv_workqueue);
 		if (send_workqueue)
 			flush_workqueue(send_workqueue);
-		idx = srcu_read_lock(&connections_srcu);
 		for (i = 0; i < CONN_HASH_SIZE && ok; i++) {
 			hlist_for_each_entry_rcu(con, &connection_hash[i],
 						 list) {
@@ -1707,14 +1733,17 @@ static void work_flush(void)
 				}
 			}
 		}
-		srcu_read_unlock(&connections_srcu, idx);
 	} while (!ok);
 }
 
 void dlm_lowcomms_stop(void)
 {
+	int idx;
+
+	idx = srcu_read_lock(&connections_srcu);
 	work_flush();
 	foreach_conn(free_conn);
+	srcu_read_unlock(&connections_srcu, idx);
 	work_stop();
 	deinit_local();
 }