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: NTom Talpey <tmt@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs2xdr.c

@@ -251,6 +251,7 @@ nfs_xdr_readargs(struct rpc_rqst *req, __be32 *p, struct nfs_readargs *args)
 	replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS_readres_sz) << 2;
 	xdr_inline_pages(&req->rq_rcv_buf, replen,
 			 args->pages, args->pgbase, count);
+	req->rq_rcv_buf.flags |= XDRBUF_READ;
 	return 0;
 }
 
@@ -313,6 +314,7 @@ nfs_xdr_writeargs(struct rpc_rqst *req, __be32 *p, struct nfs_writeargs *args)
 
 	/* Copy the page array */
 	xdr_encode_pages(sndbuf, args->pages, args->pgbase, count);
+	sndbuf->flags |= XDRBUF_WRITE;
 	return 0;
 }
 

fs/nfs/nfs3xdr.c

@@ -346,6 +346,7 @@ nfs3_xdr_readargs(struct rpc_rqst *req, __be32 *p, struct nfs_readargs *args)
 	replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS3_readres_sz) << 2;
 	xdr_inline_pages(&req->rq_rcv_buf, replen,
 			 args->pages, args->pgbase, count);
+	req->rq_rcv_buf.flags |= XDRBUF_READ;
 	return 0;
 }
 
@@ -367,6 +368,7 @@ nfs3_xdr_writeargs(struct rpc_rqst *req, __be32 *p, struct nfs_writeargs *args)
 
 	/* Copy the page array */
 	xdr_encode_pages(sndbuf, args->pages, args->pgbase, count);
+	sndbuf->flags |= XDRBUF_WRITE;
 	return 0;
 }
 

fs/nfs/nfs4xdr.c

@@ -1856,6 +1856,7 @@ static int nfs4_xdr_enc_read(struct rpc_rqst *req, __be32 *p, struct nfs_readarg
 	replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_read_sz) << 2;
 	xdr_inline_pages(&req->rq_rcv_buf, replen,
 			 args->pages, args->pgbase, args->count);
+	req->rq_rcv_buf.flags |= XDRBUF_READ;
 out:
 	return status;
 }
@@ -1932,6 +1933,7 @@ static int nfs4_xdr_enc_write(struct rpc_rqst *req, __be32 *p, struct nfs_writea
 	status = encode_write(&xdr, args);
 	if (status)
 		goto out;
+	req->rq_snd_buf.flags |= XDRBUF_WRITE;
 	status = encode_getfattr(&xdr, args->bitmask);
 out:
 	return status;

include/linux/sunrpc/xdr.h

@@ -70,7 +70,10 @@ struct xdr_buf {
 
 	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 */

net/sunrpc/clnt.c

@@ -874,6 +874,7 @@ rpc_xdr_buf_init(struct xdr_buf *buf, void *start, size_t len)
 	buf->head[0].iov_len = len;
 	buf->tail[0].iov_len = 0;
 	buf->page_len = 0;
+	buf->flags = 0;
 	buf->len = 0;
 	buf->buflen = len;
 }