[RFC v7 35/41] sunrpc: Allow to demand-allocate pages to encode into

[Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

When encoding large, variable-length objects such as acls into xdr_bufs,
it is easier to allocate buffer pages on demand rather than precomputing
the required buffer size.

Signed-off-by: Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 net/sunrpc/xdr.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 4439ac4..63c1c36 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -537,6 +537,15 @@ static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
 	 */
 	xdr->scratch.iov_base = xdr->p;
 	xdr->scratch.iov_len = frag1bytes;
+
+	if (!*xdr->page_ptr) {
+		struct page *page = alloc_page(GFP_NOFS);
+
+		if (!page)
+			return NULL;
+		*xdr->page_ptr = page;
+	}
+
 	p = page_address(*xdr->page_ptr);
 	/*
 	 * Note this is where the next encode will start after we've
-- 
2.4.3