1 files changed, 48 insertions, 57 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index f27dbfd..211ac4b 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -169,40 +169,41 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
 	return rqst->rq_rcv_buf.buflen <= ia->ri_max_inline_read;
 }
 
-/* Split "vec" on page boundaries into segments. FMR registers pages,
- * not a byte range. Other modes coalesce these segments into a single
- * MR when they can.
+/* Split @vec on page boundaries into SGEs. FMR registers pages, not
+ * a byte range. Other modes coalesce these SGEs into a single MR
+ * when they can.
+ *
+ * Returns pointer to next available SGE, and bumps the total number
+ * of SGEs consumed.
  */
-static int
-rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg, int n)
+static struct rpcrdma_mr_seg *
+rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
+		     unsigned int *n)
 {
-	size_t page_offset;
-	u32 remaining;
+	u32 remaining, page_offset;
 	char *base;
 
 	base = vec->iov_base;
 	page_offset = offset_in_page(base);
 	remaining = vec->iov_len;
-	while (remaining && n < RPCRDMA_MAX_SEGS) {
-		seg[n].mr_page = NULL;
-		seg[n].mr_offset = base;
-		seg[n].mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
-		remaining -= seg[n].mr_len;
-		base += seg[n].mr_len;
-		++n;
+	while (remaining) {
+		seg->mr_page = NULL;
+		seg->mr_offset = base;
+		seg->mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
+		remaining -= seg->mr_len;
+		base += seg->mr_len;
+		++seg;
+		++(*n);
 		page_offset = 0;
 	}
-	return n;
+	return seg;
 }
 
-/*
- * Chunk assembly from upper layer xdr_buf.
- *
- * Prepare the passed-in xdr_buf into representation as RPC/RDMA chunk
- * elements. Segments are then coalesced when registered, if possible
- * within the selected memreg mode.
+/* Convert @xdrbuf into SGEs no larger than a page each. As they
+ * are registered, these SGEs are then coalesced into RDMA segments
+ * when the selected memreg mode supports it.
  *
- * Returns positive number of segments converted, or a negative errno.
+ * Returns positive number of SGEs consumed, or a negative errno.
  */
 
 static int
@@ -210,47 +211,41 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
 		     unsigned int pos, enum rpcrdma_chunktype type,
 		     struct rpcrdma_mr_seg *seg)
 {
-	int len, n, p, page_base;
+	unsigned long page_base;
+	unsigned int len, n;
 	struct page **ppages;
 
 	n = 0;
-	if (pos == 0) {
-		n = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, n);
-		if (n == RPCRDMA_MAX_SEGS)
-			goto out_overflow;
-	}
+	if (pos == 0)
+		seg = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, &n);
 
 	len = xdrbuf->page_len;
 	ppages = xdrbuf->pages + (xdrbuf->page_base >> PAGE_SHIFT);
 	page_base = offset_in_page(xdrbuf->page_base);
-	p = 0;
-	while (len && n < RPCRDMA_MAX_SEGS) {
-		if (!ppages[p]) {
-			/* alloc the pagelist for receiving buffer */
-			ppages[p] = alloc_page(GFP_ATOMIC);
-			if (!ppages[p])
+	while (len) {
+		if (unlikely(!*ppages)) {
+			/* XXX: Certain upper layer operations do
+			 *	not provide receive buffer pages.
+			 */
+			*ppages = alloc_page(GFP_ATOMIC);
+			if (!*ppages)
 				return -EAGAIN;
 		}
-		seg[n].mr_page = ppages[p];
-		seg[n].mr_offset = (void *)(unsigned long) page_base;
-		seg[n].mr_len = min_t(u32, PAGE_SIZE - page_base, len);
-		if (seg[n].mr_len > PAGE_SIZE)
-			goto out_overflow;
-		len -= seg[n].mr_len;
+		seg->mr_page = *ppages;
+		seg->mr_offset = (char *)page_base;
+		seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len);
+		len -= seg->mr_len;
+		++ppages;
+		++seg;
 		++n;
-		++p;
-		page_base = 0;	/* page offset only applies to first page */
+		page_base = 0;
 	}
 
-	/* Message overflows the seg array */
-	if (len && n == RPCRDMA_MAX_SEGS)
-		goto out_overflow;
-
 	/* When encoding a Read chunk, the tail iovec contains an
 	 * XDR pad and may be omitted.
 	 */
 	if (type == rpcrdma_readch && r_xprt->rx_ia.ri_implicit_roundup)
-		return n;
+		goto out;
 
 	/* When encoding a Write chunk, some servers need to see an
 	 * extra segment for non-XDR-aligned Write chunks. The upper
@@ -258,19 +253,15 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
 	 * for this purpose.
 	 */
 	if (type == rpcrdma_writech && r_xprt->rx_ia.ri_implicit_roundup)
-		return n;
+		goto out;
 
-	if (xdrbuf->tail[0].iov_len) {
-		n = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, n);
-		if (n == RPCRDMA_MAX_SEGS)
-			goto out_overflow;
-	}
+	if (xdrbuf->tail[0].iov_len)
+		seg = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, &n);
 
+out:
+	if (unlikely(n > RPCRDMA_MAX_SEGS))
+		return -EIO;
 	return n;
-
-out_overflow:
-	pr_err("rpcrdma: segment array overflow\n");
-	return -EIO;
 }
 
 static inline int