SUNRPC: Optimise away unnecessary data moves in xdr_align_pages
We only have to call xdr_shrink_pagelen() if the remaining RPC
message does not fit in the page buffer length that we supplied
to xdr_align_pages().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index fbbd1c4..08f50af 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -730,21 +730,24 @@
if (xdr->nwords == 0)
return 0;
+ /* Realign pages to current pointer position */
+ iov = buf->head;
+ if (iov->iov_len > cur) {
+ xdr_shrink_bufhead(buf, iov->iov_len - cur);
+ xdr->nwords = XDR_QUADLEN(buf->len - cur);
+ }
+
if (nwords > xdr->nwords) {
nwords = xdr->nwords;
len = nwords << 2;
}
- /* Realign pages to current pointer position */
- iov = buf->head;
- if (iov->iov_len > cur)
- xdr_shrink_bufhead(buf, iov->iov_len - cur);
-
- /* Truncate page data and move it into the tail */
- if (buf->page_len > len)
- xdr_shrink_pagelen(buf, buf->page_len - len);
- else
+ if (buf->page_len <= len)
len = buf->page_len;
- xdr->nwords = XDR_QUADLEN(buf->len - cur);
+ else if (nwords < xdr->nwords) {
+ /* Truncate page data and move it into the tail */
+ xdr_shrink_pagelen(buf, buf->page_len - len);
+ xdr->nwords = XDR_QUADLEN(buf->len - cur);
+ }
return len;
}