IB/srp: Convert to new registration API

Instead of constructing a page list, call ib_map_mr_sg
and post a new ib_reg_wr. srp_map_finish_fr now returns
the number of sg elements registered.

Remove srp_finish_mapping since no one is calling it.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Tested-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 3608f2e..87a2a91 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -242,7 +242,6 @@
 struct srp_fr_desc {
 	struct list_head		entry;
 	struct ib_mr			*mr;
-	struct ib_fast_reg_page_list	*frpl;
 };
 
 /**
@@ -294,11 +293,17 @@
 		} gen;
 	};
 	struct srp_direct_buf  *desc;
-	u64		       *pages;
+	union {
+		u64			*pages;
+		struct scatterlist	*sg;
+	};
 	dma_addr_t		base_dma_addr;
 	u32			dma_len;
 	u32			total_len;
-	unsigned int		npages;
+	union {
+		unsigned int	npages;
+		int		sg_nents;
+	};
 	unsigned int		nmdesc;
 	unsigned int		ndesc;
 };