drbd: Preallocate one page per drbd_socket as a send buffer

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

drivers/block/drbd/drbd_int.h

@@ -556,27 +556,6 @@ struct p_delay_probe93 {
 
 #define DRBD_SOCKET_BUFFER_SIZE 4096
 
-union p_polymorph {
-        struct p_header           header;
-        struct p_handshake       handshake;
-        struct p_data            data;
-        struct p_block_ack       block_ack;
-        struct p_barrier         barrier;
-        struct p_barrier_ack     barrier_ack;
-        struct p_rs_param_89     rs_param_89;
-        struct p_rs_param_95     rs_param_95;
-        struct p_protocol        protocol;
-        struct p_sizes           sizes;
-        struct p_uuids           uuids;
-        struct p_state           state;
-        struct p_req_state       req_state;
-        struct p_req_state_reply req_state_reply;
-        struct p_block_req       block_req;
-	struct p_delay_probe93   delay_probe93;
-	struct p_rs_uuid         rs_uuid;
-	struct p_block_desc      block_desc;
-} __packed;
-
 /**********************************************************************/
 enum drbd_thread_state {
 	NONE,
@@ -804,7 +783,7 @@ struct drbd_socket {
 	struct socket    *socket;
 	/* this way we get our
 	 * send/receive buffers off the stack */
-	union p_polymorph sbuf;
+	void *sbuf;
 	void *rbuf;
 };
 

drivers/block/drbd/drbd_main.c

@@ -800,7 +800,7 @@ int drbd_send_sync_param(struct drbd_conf *mdev)
 		enum drbd_packet cmd =
 			apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
 
-		p = &mdev->tconn->data.sbuf.rs_param_95;
+		p = mdev->tconn->data.sbuf;
 
 		/* initialize verify_alg and csums_alg */
 		memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
@@ -2277,11 +2277,15 @@ static int drbd_alloc_socket(struct drbd_socket *socket)
 	socket->rbuf = (void *) __get_free_page(GFP_KERNEL);
 	if (!socket->rbuf)
 		return -ENOMEM;
+	socket->sbuf = (void *) __get_free_page(GFP_KERNEL);
+	if (!socket->sbuf)
+		return -ENOMEM;
 	return 0;
 }
 
 static void drbd_free_socket(struct drbd_socket *socket)
 {
+	free_page((unsigned long) socket->sbuf);
 	free_page((unsigned long) socket->rbuf);
 }
 

drivers/block/drbd/drbd_receiver.c

@@ -736,7 +736,7 @@ static struct socket *drbd_wait_for_connect(struct drbd_tconn *tconn)
 
 static int drbd_send_fp(struct drbd_tconn *tconn, struct socket *sock, enum drbd_packet cmd)
 {
-	struct p_header *h = &tconn->data.sbuf.header;
+	struct p_header *h = tconn->data.sbuf;
 
 	return !_conn_send_cmd(tconn, 0, sock, cmd, h, sizeof(*h), 0);
 }
@@ -4138,7 +4138,7 @@ static int drbd_disconnected(int vnr, void *p, void *data)
 static int drbd_send_handshake(struct drbd_tconn *tconn)
 {
 	/* ASSERT current == mdev->tconn->receiver ... */
-	struct p_handshake *p = &tconn->data.sbuf.handshake;
+	struct p_handshake *p = tconn->data.sbuf;
 	int err;
 
 	if (mutex_lock_interruptible(&tconn->data.mutex)) {

drivers/block/drbd/drbd_worker.c

@@ -1193,7 +1193,7 @@ int w_send_barrier(struct drbd_work *w, int cancel)
 {
 	struct drbd_tl_epoch *b = container_of(w, struct drbd_tl_epoch, w);
 	struct drbd_conf *mdev = w->mdev;
-	struct p_barrier *p = &mdev->tconn->data.sbuf.barrier;
+	struct p_barrier *p = mdev->tconn->data.sbuf;
 	int err = 0;
 
 	/* really avoid racing with tl_clear.  w.cb may have been referenced