SUNRPC: mark bulk read/write data in xdrbuf

Adds a flag word to the xdrbuf struct which indicates any bulk
disposition of the data. This enables RPC transport providers to
marshal it efficiently/appropriately, and may enable other
optimizations.

Signed-off-by: Tom Talpey <tmt@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index c6b53d1..0751c94 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -70,7 +70,10 @@
 
 	struct page **	pages;		/* Array of contiguous pages */
 	unsigned int	page_base,	/* Start of page data */
-			page_len;	/* Length of page data */
+			page_len,	/* Length of page data */
+			flags;		/* Flags for data disposition */
+#define XDRBUF_READ		0x01		/* target of file read */
+#define XDRBUF_WRITE		0x02		/* source of file write */
 
 	unsigned int	buflen,		/* Total length of storage buffer */
 			len;		/* Length of XDR encoded message */