NFSv4: Try to recover from getfh failures in nfs4_xdr_dec_open

Try harder to recover the open state if the server failed to return a
filehandle.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -66,6 +66,8 @@ static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry
 static int nfs4_handle_exception(const struct nfs_server *server, int errorcode, struct nfs4_exception *exception);
 static int nfs4_wait_clnt_recover(struct rpc_clnt *clnt, struct nfs_client *clp);
 static int _nfs4_do_access(struct inode *inode, struct rpc_cred *cred, int openflags);
+static int _nfs4_proc_lookup(struct inode *dir, const struct qstr *name, struct nfs_fh *fhandle, struct nfs_fattr *fattr);
+static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr);
 
 /* Prevent leaks of NFSv4 errors into userland */
 int nfs4_map_errors(int err)
@@ -930,6 +932,9 @@ static int _nfs4_proc_open(struct nfs4_opendata *data)
 	if (status != 0 || !data->rpc_done)
 		return status;
 
+	if (o_res->fh.size == 0)
+		_nfs4_proc_lookup(dir, o_arg->name, &o_res->fh, o_res->f_attr);
+
 	if (o_arg->open_flags & O_CREAT) {
 		update_changeattr(dir, &o_res->cinfo);
 		nfs_post_op_update_inode(dir, o_res->dir_attr);
@@ -941,7 +946,7 @@ static int _nfs4_proc_open(struct nfs4_opendata *data)
 			return status;
 	}
 	if (!(o_res->f_attr->valid & NFS_ATTR_FATTR))
-		return server->nfs_client->rpc_ops->getattr(server, &o_res->fh, o_res->f_attr);
+		_nfs4_proc_getattr(server, &o_res->fh, o_res->f_attr);
 	return 0;
 }
 

fs/nfs/nfs4xdr.c

@@ -3161,11 +3161,12 @@ static int decode_getfh(struct xdr_stream *xdr, struct nfs_fh *fh)
 	uint32_t len;
 	int status;
 
+	/* Zero handle first to allow comparisons */
+	memset(fh, 0, sizeof(*fh));
+
 	status = decode_op_hdr(xdr, OP_GETFH);
 	if (status)
 		return status;
-	/* Zero handle first to allow comparisons */
-	memset(fh, 0, sizeof(*fh));
 
 	READ_BUF(4);
 	READ32(len);
@@ -4030,8 +4031,7 @@ static int nfs4_xdr_dec_open(struct rpc_rqst *rqstp, __be32 *p, struct nfs_openr
         status = decode_open(&xdr, res);
         if (status)
                 goto out;
-	status = decode_getfh(&xdr, &res->fh);
-        if (status)
+	if (decode_getfh(&xdr, &res->fh) != 0)
 		goto out;
 	if (decode_getfattr(&xdr, res->f_attr, res->server) != 0)
 		goto out;