NFSv4: use the (more efficient) NFSv2/v3-like XDR scheme for generating

READLINK RPC calls.

fs/nfs/nfs4proc.c

@@ -187,18 +187,6 @@ nfs4_setup_readdir(struct nfs4_compound *cp, u64 cookie, u32 *verifier,
 	kunmap_atomic(start, KM_USER0);
 }
 
-static void
-nfs4_setup_readlink(struct nfs4_compound *cp, int count, struct page **pages)
-{
-	struct nfs4_readlink *readlink = GET_OP(cp, readlink);
-
-	readlink->rl_count = count;
-	readlink->rl_pages = pages;
-
-	OPNUM(cp) = OP_READLINK;
-	cp->req_nops++;
-}
-
 static void
 renew_lease(struct nfs_server *server, unsigned long timestamp)
 {
@@ -885,16 +873,20 @@ static int nfs4_proc_access(struct inode *inode, struct rpc_cred *cred, int mode
  * Both of these changes to the XDR layer would in fact be quite
  * minor, but I decided to leave them for a subsequent patch.
  */
-static int
-nfs4_proc_readlink(struct inode *inode, struct page *page)
+static int nfs4_proc_readlink(struct inode *inode, struct page *page)
 {
-	struct nfs4_compound	compound;
-	struct nfs4_op		ops[2];
+	struct nfs4_readlink args = {
+		.fh       = NFS_FH(inode),
+		.count    = PAGE_CACHE_SIZE,
+		.pages    = &page,
+	};
+	struct rpc_message msg = {
+		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READLINK],
+		.rpc_argp = &args,
+		.rpc_resp = NULL,
+	};
 
-	nfs4_setup_compound(&compound, ops, NFS_SERVER(inode), "readlink");
-	nfs4_setup_putfh(&compound, NFS_FH(inode));
-	nfs4_setup_readlink(&compound, PAGE_CACHE_SIZE, &page);
-	return nfs4_map_errors(nfs4_call_compound(&compound, NULL, 0));
+	return nfs4_map_errors(rpc_call_sync(NFS_CLIENT(inode), &msg, 0));
 }
 
 static int

fs/nfs/nfs4xdr.c

@@ -132,6 +132,12 @@ static int nfs_stat_to_errno(int);
 #define NFS4_dec_read_sz	(compound_decode_hdr_maxsz + \
 				decode_putfh_maxsz + \
 				op_decode_hdr_maxsz + 2)
+#define NFS4_enc_readlink_sz	(compound_encode_hdr_maxsz + \
+				encode_putfh_maxsz + \
+				op_encode_hdr_maxsz)
+#define NFS4_dec_readlink_sz	(compound_decode_hdr_maxsz + \
+				decode_putfh_maxsz + \
+				op_decode_hdr_maxsz)
 #define NFS4_enc_write_sz	(compound_encode_hdr_maxsz + \
 				encode_putfh_maxsz + \
 				op_encode_hdr_maxsz + 8)
@@ -963,8 +969,7 @@ encode_readdir(struct xdr_stream *xdr, struct nfs4_readdir *readdir, struct rpc_
 	return 0;
 }
 
-static int
-encode_readlink(struct xdr_stream *xdr, struct nfs4_readlink *readlink, struct rpc_rqst *req)
+static int encode_readlink(struct xdr_stream *xdr, const struct nfs4_readlink *readlink, struct rpc_rqst *req)
 {
 	struct rpc_auth *auth = req->rq_task->tk_auth;
 	int replen;
@@ -978,7 +983,7 @@ encode_readlink(struct xdr_stream *xdr, struct nfs4_readlink *readlink, struct r
 	 *      + OP_READLINK + status  = 7
 	 */
 	replen = (RPC_REPHDRSIZE + auth->au_rslack + 7) << 2;
-	xdr_inline_pages(&req->rq_rcv_buf, replen, readlink->rl_pages, 0, readlink->rl_count);
+	xdr_inline_pages(&req->rq_rcv_buf, replen, readlink->pages, 0, readlink->count);
 	
 	return 0;
 }
@@ -1144,9 +1149,6 @@ encode_compound(struct xdr_stream *xdr, struct nfs4_compound *cp, struct rpc_rqs
 		case OP_READDIR:
 			status = encode_readdir(xdr, &cp->ops[i].u.readdir, req);
 			break;
-		case OP_READLINK:
-			status = encode_readlink(xdr, &cp->ops[i].u.readlink, req);
-			break;
 		default:
 			BUG();
 		}
@@ -1541,6 +1543,27 @@ nfs4_xdr_enc_locku(struct rpc_rqst *req, uint32_t *p, struct nfs_lockargs *args)
 	return status;
 }
 
+/*
+ * Encode a READLINK request
+ */
+static int nfs4_xdr_enc_readlink(struct rpc_rqst *req, uint32_t *p, const struct nfs4_readlink *args)
+{
+	struct xdr_stream xdr;
+	struct compound_hdr hdr = {
+		.nops = 2,
+	};
+	int status;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_compound_hdr(&xdr, &hdr);
+	status = encode_putfh(&xdr, args->fh);
+	if(status)
+		goto out;
+	status = encode_readlink(&xdr, args, req);
+out:
+	return status;
+}
+
 /*
  * Encode a READ request
  */
@@ -3018,8 +3041,7 @@ decode_readdir(struct xdr_stream *xdr, struct rpc_rqst *req, struct nfs4_readdir
 	return -errno_NFSERR_IO;
 }
 
-static int
-decode_readlink(struct xdr_stream *xdr, struct rpc_rqst *req, struct nfs4_readlink *readlink)
+static int decode_readlink(struct xdr_stream *xdr, struct rpc_rqst *req)
 {
 	struct xdr_buf *rcvbuf = &req->rq_rcv_buf;
 	struct iovec *iov = rcvbuf->head;
@@ -3220,9 +3242,6 @@ decode_compound(struct xdr_stream *xdr, struct nfs4_compound *cp, struct rpc_rqs
 		case OP_READDIR:
 			status = decode_readdir(xdr, req, &op->u.readdir);
 			break;
-		case OP_READLINK:
-			status = decode_readlink(xdr, req, &op->u.readlink);
-			break;
 		default:
 			BUG();
 			return -EIO;
@@ -3651,6 +3670,27 @@ nfs4_xdr_dec_locku(struct rpc_rqst *rqstp, uint32_t *p, struct nfs_lockres *res)
 	return status;
 }
 
+/*
+ * Decode READLINK response
+ */
+static int nfs4_xdr_dec_readlink(struct rpc_rqst *rqstp, uint32_t *p, void *res)
+{
+	struct xdr_stream xdr;
+	struct compound_hdr hdr;
+	int status;
+
+	xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
+	status = decode_compound_hdr(&xdr, &hdr);
+	if (status)
+		goto out;
+	status = decode_putfh(&xdr);
+	if (status)
+		goto out;
+	status = decode_readlink(&xdr, rqstp);
+out:
+	return status;
+}
+
 /*
  * Decode Read response
  */
@@ -3982,6 +4022,7 @@ struct rpc_procinfo	nfs4_procedures[] = {
   PROC(CREATE,		enc_create,	dec_create),
   PROC(PATHCONF,	enc_pathconf,	dec_pathconf),
   PROC(STATFS,		enc_statfs,	dec_statfs),
+  PROC(READLINK,	enc_readlink,	dec_readlink),
 };
 
 struct rpc_version		nfs_version4 = {

include/linux/nfs4.h

@@ -313,6 +313,7 @@ enum {
 	NFSPROC4_CLNT_CREATE,
 	NFSPROC4_CLNT_PATHCONF,
 	NFSPROC4_CLNT_STATFS,
+	NFSPROC4_CLNT_READLINK,
 };
 
 #endif

include/linux/nfs_xdr.h

@@ -609,8 +609,9 @@ struct nfs4_readdir {
 };
 
 struct nfs4_readlink {
-	u32				rl_count;   /* zero-copy data */
-	struct page **			rl_pages;   /* zero-copy data */
+	const struct nfs_fh *		fh;
+	u32				count;   /* zero-copy data */
+	struct page **			pages;   /* zero-copy data */
 };
 
 struct nfs4_remove_arg {