IB: split struct ib_send_wr

This patch split up struct ib_send_wr so that all non-trivial verbs
use their own structure which embedds struct ib_send_wr.  This dramaticly
shrinks the size of a WR for most common operations:

sizeof(struct ib_send_wr) (old):	96

sizeof(struct ib_send_wr):		48
sizeof(struct ib_rdma_wr):		64
sizeof(struct ib_atomic_wr):		96
sizeof(struct ib_ud_wr):		88
sizeof(struct ib_fast_reg_wr):		88
sizeof(struct ib_bind_mw_wr):		96
sizeof(struct ib_sig_handover_wr):	80

And with Sagi's pending MR rework the fast registration WR will also be
down to a reasonable size:

sizeof(struct ib_fastreg_wr):		64

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> [srp, srpt]
Reviewed-by: Chuck Lever <chuck.lever@oracle.com> [sunrpc]
Tested-by: Haggai Eran <haggaie@mellanox.com>
Tested-by: Sagi Grimberg <sagig@mellanox.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
index 2542fd3..5bba176 100644
--- a/drivers/infiniband/hw/mlx4/mr.c
+++ b/drivers/infiniband/hw/mlx4/mr.c
@@ -321,21 +321,21 @@
 int mlx4_ib_bind_mw(struct ib_qp *qp, struct ib_mw *mw,
 		    struct ib_mw_bind *mw_bind)
 {
-	struct ib_send_wr  wr;
+	struct ib_bind_mw_wr  wr;
 	struct ib_send_wr *bad_wr;
 	int ret;
 
 	memset(&wr, 0, sizeof(wr));
-	wr.opcode               = IB_WR_BIND_MW;
-	wr.wr_id                = mw_bind->wr_id;
-	wr.send_flags           = mw_bind->send_flags;
-	wr.wr.bind_mw.mw        = mw;
-	wr.wr.bind_mw.bind_info = mw_bind->bind_info;
-	wr.wr.bind_mw.rkey      = ib_inc_rkey(mw->rkey);
+	wr.wr.opcode		= IB_WR_BIND_MW;
+	wr.wr.wr_id		= mw_bind->wr_id;
+	wr.wr.send_flags	= mw_bind->send_flags;
+	wr.mw			= mw;
+	wr.bind_info		= mw_bind->bind_info;
+	wr.rkey			= ib_inc_rkey(mw->rkey);
 
-	ret = mlx4_ib_post_send(qp, &wr, &bad_wr);
+	ret = mlx4_ib_post_send(qp, &wr.wr, &bad_wr);
 	if (!ret)
-		mw->rkey = wr.wr.bind_mw.rkey;
+		mw->rkey = wr.rkey;
 
 	return ret;
 }