sunrpc: fix NFSACL RPC retry on soft mount

It used to be quite awhile ago since 1b63a75 ('SUNRPC: Refactor
rpc_clone_client()'), in 2012, that `cl_timeout` was copied in so that
all mount parameters propagate to NFSACL clients. However since that
change, if mount options as follows are given:

    soft,timeo=50,retrans=16,vers=3

The resultant NFSACL client receives:

    cl_softrtry: 1
    cl_timeout: to_initval=60000, to_maxval=60000, to_increment=0, to_retries=2, to_exponential=0

These values lead to NFSACL operations not being retried under the
condition of transient network outages with soft mount. Instead, getacl
call fails after 60 seconds with EIO.

The simple fix is to pass the existing client's `cl_timeout` as the new
client timeout.

Cc: Chuck Lever <[email protected]>
Cc: Benjamin Coddington <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/T/
Fixes: 1b63a75 ('SUNRPC: Refactor rpc_clone_client()')
Signed-off-by: Dan Aloni <[email protected]>
Reviewed-by: Benjamin Coddington <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>

net/sunrpc/clnt.c

@@ -1071,6 +1071,7 @@ struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
 		.authflavor	= old->cl_auth->au_flavor,
 		.cred		= old->cl_cred,
 		.stats		= old->cl_stats,
+		.timeout	= old->cl_timeout,
 	};
 	struct rpc_clnt *clnt;
 	int err;