drbd: refactor use of first_peer_device()

Reduce the number of calls to first_peer_device(). Instead, call
first_peer_device() just once to assign a local variable peer_device.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 18 insertions, 12 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 25f4b6f67c21..0bf8a6082bb8 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -552,8 +552,10 @@ void conn_try_outdate_peer_async(struct drbd_connection *connection)
 }
 
 enum drbd_state_rv
-drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
+drbd_set_role(struct drbd_device *const device, enum drbd_role new_role, int force)
 {
+	struct drbd_peer_device *const peer_device = first_peer_device(device);
+	struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
 	const int max_tries = 4;
 	enum drbd_state_rv rv = SS_UNKNOWN_ERROR;
 	struct net_conf *nc;
@@ -601,7 +603,7 @@ drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
 		    device->state.disk == D_CONSISTENT && mask.pdsk == 0) {
 			D_ASSERT(device, device->state.pdsk == D_UNKNOWN);
 
-			if (conn_try_outdate_peer(first_peer_device(device)->connection)) {
+			if (conn_try_outdate_peer(connection)) {
 				val.disk = D_UP_TO_DATE;
 				mask.disk = D_MASK;
 			}
@@ -611,7 +613,7 @@ drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
 		if (rv == SS_NOTHING_TO_DO)
 			goto out;
 		if (rv == SS_PRIMARY_NOP && mask.pdsk == 0) {
-			if (!conn_try_outdate_peer(first_peer_device(device)->connection) && force) {
+			if (!conn_try_outdate_peer(connection) && force) {
 				drbd_warn(device, "Forced into split brain situation!\n");
 				mask.pdsk = D_MASK;
 				val.pdsk  = D_OUTDATED;
@@ -624,7 +626,7 @@ drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
 			   retry at most once more in this case. */
 			int timeo;
 			rcu_read_lock();
-			nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
+			nc = rcu_dereference(connection->net_conf);
 			timeo = nc ? (nc->ping_timeo + 1) * HZ / 10 : 1;
 			rcu_read_unlock();
 			schedule_timeout_interruptible(timeo);
@@ -661,7 +663,7 @@ drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
 	} else {
 		/* Called from drbd_adm_set_role only.
 		 * We are still holding the conf_update mutex. */
-		nc = first_peer_device(device)->connection->net_conf;
+		nc = connection->net_conf;
 		if (nc)
 			nc->discard_my_data = 0; /* without copy; single bit op is atomic */
 
@@ -683,8 +685,8 @@ drbd_set_role(struct drbd_device *device, enum drbd_role new_role, int force)
 	if (device->state.conn >= C_WF_REPORT_PARAMS) {
 		/* if this was forced, we should consider sync */
 		if (forced)
-			drbd_send_uuids(first_peer_device(device));
-		drbd_send_current_state(first_peer_device(device));
+			drbd_send_uuids(peer_device);
+		drbd_send_current_state(peer_device);
 	}
 
 	drbd_md_sync(device);
@@ -1433,6 +1435,8 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 {
 	struct drbd_config_context adm_ctx;
 	struct drbd_device *device;
+	struct drbd_peer_device *peer_device;
+	struct drbd_connection *connection;
 	int err;
 	enum drbd_ret_code retcode;
 	enum determine_dev_size dd;
@@ -1455,7 +1459,9 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 
 	device = adm_ctx.device;
 	mutex_lock(&adm_ctx.resource->adm_mutex);
-	conn_reconfig_start(first_peer_device(device)->connection);
+	peer_device = first_peer_device(device);
+	connection = peer_device ? peer_device->connection : NULL;
+	conn_reconfig_start(connection);
 
 	/* if you want to reconfigure, please tear down first */
 	if (device->state.disk > D_DISKLESS) {
@@ -1522,7 +1528,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 		goto fail;
 
 	rcu_read_lock();
-	nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
+	nc = rcu_dereference(connection->net_conf);
 	if (nc) {
 		if (new_disk_conf->fencing == FP_STONITH && nc->wire_protocol == DRBD_PROT_A) {
 			rcu_read_unlock();
@@ -1642,7 +1648,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 	 */
 	wait_event(device->misc_wait, !atomic_read(&device->ap_pending_cnt) || drbd_suspended(device));
 	/* and for any other previously queued work */
-	drbd_flush_workqueue(&first_peer_device(device)->connection->sender_work);
+	drbd_flush_workqueue(&connection->sender_work);
 
 	rv = _drbd_request_state(device, NS(disk, D_ATTACHING), CS_VERBOSE);
 	retcode = rv;  /* FIXME: Type mismatch. */
@@ -1838,7 +1844,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 
 	kobject_uevent(&disk_to_dev(device->vdisk)->kobj, KOBJ_CHANGE);
 	put_ldev(device);
-	conn_reconfig_done(first_peer_device(device)->connection);
+	conn_reconfig_done(connection);
 	mutex_unlock(&adm_ctx.resource->adm_mutex);
 	drbd_adm_finish(&adm_ctx, info, retcode);
 	return 0;
@@ -1849,7 +1855,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 	drbd_force_state(device, NS(disk, D_DISKLESS));
 	drbd_md_sync(device);
  fail:
-	conn_reconfig_done(first_peer_device(device)->connection);
+	conn_reconfig_done(connection);
 	if (nbc) {
 		if (nbc->backing_bdev)
 			blkdev_put(nbc->backing_bdev,