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/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 7845fae..25f022c 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1100,54 +1100,94 @@
 		__be32		imm_data;
 		u32		invalidate_rkey;
 	} ex;
-	union {
-		struct {
-			u64	remote_addr;
-			u32	rkey;
-		} rdma;
-		struct {
-			u64	remote_addr;
-			u64	compare_add;
-			u64	swap;
-			u64	compare_add_mask;
-			u64	swap_mask;
-			u32	rkey;
-		} atomic;
-		struct {
-			struct ib_ah *ah;
-			void   *header;
-			int     hlen;
-			int     mss;
-			u32	remote_qpn;
-			u32	remote_qkey;
-			u16	pkey_index; /* valid for GSI only */
-			u8	port_num;   /* valid for DR SMPs on switch only */
-		} ud;
-		struct {
-			u64				iova_start;
-			struct ib_fast_reg_page_list   *page_list;
-			unsigned int			page_shift;
-			unsigned int			page_list_len;
-			u32				length;
-			int				access_flags;
-			u32				rkey;
-		} fast_reg;
-		struct {
-			struct ib_mw            *mw;
-			/* The new rkey for the memory window. */
-			u32                      rkey;
-			struct ib_mw_bind_info   bind_info;
-		} bind_mw;
-		struct {
-			struct ib_sig_attrs    *sig_attrs;
-			struct ib_mr	       *sig_mr;
-			int			access_flags;
-			struct ib_sge	       *prot;
-		} sig_handover;
-	} wr;
 	u32			xrc_remote_srq_num;	/* XRC TGT QPs only */
 };
 
+struct ib_rdma_wr {
+	struct ib_send_wr	wr;
+	u64			remote_addr;
+	u32			rkey;
+};
+
+static inline struct ib_rdma_wr *rdma_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_rdma_wr, wr);
+}
+
+struct ib_atomic_wr {
+	struct ib_send_wr	wr;
+	u64			remote_addr;
+	u64			compare_add;
+	u64			swap;
+	u64			compare_add_mask;
+	u64			swap_mask;
+	u32			rkey;
+};
+
+static inline struct ib_atomic_wr *atomic_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_atomic_wr, wr);
+}
+
+struct ib_ud_wr {
+	struct ib_send_wr	wr;
+	struct ib_ah		*ah;
+	void			*header;
+	int			hlen;
+	int			mss;
+	u32			remote_qpn;
+	u32			remote_qkey;
+	u16			pkey_index; /* valid for GSI only */
+	u8			port_num;   /* valid for DR SMPs on switch only */
+};
+
+static inline struct ib_ud_wr *ud_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_ud_wr, wr);
+}
+
+struct ib_fast_reg_wr {
+	struct ib_send_wr	wr;
+	u64			iova_start;
+	struct ib_fast_reg_page_list *page_list;
+	unsigned int		page_shift;
+	unsigned int		page_list_len;
+	u32			length;
+	int			access_flags;
+	u32			rkey;
+};
+
+static inline struct ib_fast_reg_wr *fast_reg_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_fast_reg_wr, wr);
+}
+
+struct ib_bind_mw_wr {
+	struct ib_send_wr	wr;
+	struct ib_mw		*mw;
+	/* The new rkey for the memory window. */
+	u32			rkey;
+	struct ib_mw_bind_info	bind_info;
+};
+
+static inline struct ib_bind_mw_wr *bind_mw_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_bind_mw_wr, wr);
+}
+
+struct ib_sig_handover_wr {
+	struct ib_send_wr	wr;
+	struct ib_sig_attrs    *sig_attrs;
+	struct ib_mr	       *sig_mr;
+	int			access_flags;
+	struct ib_sge	       *prot;
+};
+
+static inline struct ib_sig_handover_wr *sig_handover_wr(struct ib_send_wr *wr)
+{
+	return container_of(wr, struct ib_sig_handover_wr, wr);
+}
+
 struct ib_recv_wr {
 	struct ib_recv_wr      *next;
 	u64			wr_id;