xprtrdma: Refactor invocations of offset_in_page()

Clean up so that offset_in_page() is invoked less often in the
most common case, which is mapping xdr->pages.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/frwr_ops.c

@@ -306,16 +306,14 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 	if (nsegs > ep->re_max_fr_depth)
 		nsegs = ep->re_max_fr_depth;
 	for (i = 0; i < nsegs;) {
-		sg_set_page(&mr->mr_sg[i],
-			    seg->mr_page,
-			    seg->mr_len,
-			    offset_in_page(seg->mr_offset));
+		sg_set_page(&mr->mr_sg[i], seg->mr_page,
+			    seg->mr_len, seg->mr_offset);
 
 		++seg;
 		++i;
 		if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
 			continue;
-		if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
+		if ((i < nsegs && seg->mr_offset) ||
 		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
 			break;
 	}

net/sunrpc/xprtrdma/rpc_rdma.c

@@ -214,7 +214,7 @@ rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
 		     unsigned int *n)
 {
 	seg->mr_page = virt_to_page(vec->iov_base);
-	seg->mr_offset = vec->iov_base;
+	seg->mr_offset = offset_in_page(vec->iov_base);
 	seg->mr_len = vec->iov_len;
 	++seg;
 	++(*n);
@@ -246,7 +246,7 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
 	page_base = offset_in_page(xdrbuf->page_base);
 	while (len) {
 		seg->mr_page = *ppages;
-		seg->mr_offset = (char *)page_base;
+		seg->mr_offset = page_base;
 		seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len);
 		len -= seg->mr_len;
 		++ppages;

net/sunrpc/xprtrdma/xprt_rdma.h

@@ -287,7 +287,7 @@ enum {
 struct rpcrdma_mr_seg {
 	u32		mr_len;		/* length of segment */
 	struct page	*mr_page;	/* underlying struct page */
-	char		*mr_offset;	/* IN: page offset, OUT: iova */
+	u64		mr_offset;	/* IN: page offset, OUT: iova */
 };
 
 /* The Send SGE array is provisioned to send a maximum size