Return-Path: Received: from mail-yi0-f46.google.com ([209.85.218.46]:50715 "EHLO mail-yi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754072Ab1EITgx (ORCPT ); Mon, 9 May 2011 15:36:53 -0400 Received: by yia27 with SMTP id 27so1915432yia.19 for ; Mon, 09 May 2011 12:36:53 -0700 (PDT) From: Chuck Lever Subject: [PATCH 04/16] SUNRPC: Add a helper to switch the transport of the rpc_client To: trond.myklebust@netapp.com Cc: linux-nfs@vger.kernel.org Date: Mon, 09 May 2011 15:36:49 -0400 Message-ID: <20110509193649.16568.42738.stgit@matisse.1015granger.net> In-Reply-To: <20110509192522.16568.59082.stgit@matisse.1015granger.net> References: <20110509192522.16568.59082.stgit@matisse.1015granger.net> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 From: Trond Myklebust Signed-off-by: Trond Myklebust [ cel: fix whitespace ] Signed-off-by: Chuck Lever --- include/linux/sunrpc/clnt.h | 3 ++ net/sunrpc/clnt.c | 76 ++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 73 insertions(+), 6 deletions(-) diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h index 2eea0d7..d18d952 100644 --- a/include/linux/sunrpc/clnt.h +++ b/include/linux/sunrpc/clnt.h @@ -144,6 +144,9 @@ void rpc_task_release_client(struct rpc_task *); int rpc_lock_client(struct rpc_clnt *clnt, unsigned long timeout); void rpc_unlock_client(struct rpc_clnt *clnt); +int rpc_switch_client_transport(struct rpc_clnt *, + struct xprt_create *, + const struct rpc_timeout *); int rpcb_register(u32, u32, int, unsigned short); int rpcb_v4_register(const u32 program, const u32 version, diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 6479e1d..ac2d29e 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -143,12 +144,35 @@ err: return error; } +static void rpc_set_client_transport(struct rpc_clnt *clnt, + struct rpc_xprt *xprt, + const struct rpc_timeout *timeout) +{ + struct rpc_xprt *old; + + spin_lock(&clnt->cl_lock); + old = clnt->cl_xprt; + + if (!xprt_bound(xprt)) + clnt->cl_autobind = 1; + + clnt->cl_timeout = timeout; + rcu_assign_pointer(clnt->cl_xprt, xprt); + spin_unlock(&clnt->cl_lock); + + if (old != NULL) { + synchronize_rcu(); + xprt_put(old); + } +} + static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, struct rpc_xprt *xprt) { struct rpc_program *program = args->program; struct rpc_version *version; struct rpc_clnt *clnt = NULL; struct rpc_auth *auth; + const struct rpc_timeout *timeout; int err; /* sanity check the name before trying to print it */ @@ -174,7 +198,6 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru goto out_err; clnt->cl_parent = clnt; - rcu_assign_pointer(clnt->cl_xprt, xprt); clnt->cl_procinfo = version->procs; clnt->cl_maxproc = version->nrprocs; clnt->cl_protname = program->name; @@ -189,16 +212,15 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru INIT_LIST_HEAD(&clnt->cl_tasks); spin_lock_init(&clnt->cl_lock); - if (!xprt_bound(xprt)) - clnt->cl_autobind = 1; - - clnt->cl_timeout = xprt->timeout; + timeout = xprt->timeout; if (args->timeout != NULL) { memcpy(&clnt->cl_timeout_default, args->timeout, sizeof(clnt->cl_timeout_default)); - clnt->cl_timeout = &clnt->cl_timeout_default; + timeout = &clnt->cl_timeout_default; } + rpc_set_client_transport(clnt, xprt, timeout); + clnt->cl_rtt = &clnt->cl_rtt_default; rpc_init_rtt(&clnt->cl_rtt_default, clnt->cl_timeout->to_initval); clnt->cl_principal = NULL; @@ -412,6 +434,48 @@ out_no_clnt: } EXPORT_SYMBOL_GPL(rpc_clone_client); +/** + * rpc_switch_client_transport: switch the RPC transport on the fly + * @clnt: pointer to a struct rpc_clnt + * @args: pointer to the new transport arguments + * @timeout: pointer to the new timeout parameters + * + * This function allows the caller to switch the RPC transport for the + * rpc_clnt structure 'clnt' to allow it to connect to a mirrored NFS server, + * for instance. It assumes that the caller has ensured that there are no + * active tasks by using some form of locking. + */ +int rpc_switch_client_transport(struct rpc_clnt *clnt, + struct xprt_create *args, + const struct rpc_timeout *timeout) +{ + struct rpc_xprt *xprt; + struct rpc_auth *auth; + rpc_authflavor_t pseudoflavor; + + xprt = xprt_create_transport(args); + if (IS_ERR(xprt)) + return PTR_ERR(xprt); + + pseudoflavor = clnt->cl_auth->au_flavor; + + rpc_set_client_transport(clnt, xprt, timeout); + + /* + * Note: we must always create a new rpc_auth cache + * when switching to a different server! RPCSEC_GSS sessions + * in particular are between a single client and server, + * so we cannot reuse the sessions in the cache when we switch + * servers. + */ + auth = rpcauth_create(pseudoflavor, clnt); + if (IS_ERR(auth)) + return PTR_ERR(auth); + + return 0; +} +EXPORT_SYMBOL_GPL(rpc_switch_client_transport); + /* * Kill all tasks for the given client. * XXX: kill their descendants as well?