From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Add an RPC client API to redirect an rpc_clnt's transport from a
source server to a destination server during a migration event.
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
[ cel: forward ported to 3.12 ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/sunrpc/clnt.h | 4 ++
net/sunrpc/clnt.c | 107 ++++++++++++++++++++++++++++++++++++++++---
2 files changed, 104 insertions(+), 7 deletions(-)
diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 6740801..e90c543 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -134,6 +134,10 @@ void rpc_task_reset_client(struct rpc_task *task, struct rpc_clnt *clnt);
struct rpc_clnt *rpc_clone_client(struct rpc_clnt *);
struct rpc_clnt *rpc_clone_client_set_auth(struct rpc_clnt *,
rpc_authflavor_t);
+int rpc_switch_client_transport(struct rpc_clnt *,
+ struct xprt_create *,
+ const struct rpc_timeout *);
+
void rpc_shutdown_client(struct rpc_clnt *);
void rpc_release_client(struct rpc_clnt *);
void rpc_task_release_client(struct rpc_task *);
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 1aa361b..d2c8091 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -25,6 +25,7 @@
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/slab.h>
+#include <linux/rcupdate.h>
#include <linux/utsname.h>
#include <linux/workqueue.h>
#include <linux/in.h>
@@ -264,6 +265,25 @@ void rpc_clients_notifier_unregister(void)
return rpc_pipefs_notifier_unregister(&rpc_clients_block);
}
+static struct rpc_xprt *rpc_clnt_set_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);
+
+ return old;
+}
+
static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)
{
clnt->cl_nodelen = strlen(nodename);
@@ -338,7 +358,8 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
{
const struct rpc_program *program = args->program;
const struct rpc_version *version;
- struct rpc_clnt *clnt = NULL;
+ struct rpc_clnt *clnt = NULL;
+ const struct rpc_timeout *timeout;
int err;
/* sanity check the name before trying to print it */
@@ -366,7 +387,6 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
if (err)
goto out_no_clid;
- rcu_assign_pointer(clnt->cl_xprt, xprt);
clnt->cl_procinfo = version->procs;
clnt->cl_maxproc = version->nrprocs;
clnt->cl_prog = args->prognumber ? : program->number;
@@ -381,16 +401,15 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
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_clnt_set_transport(clnt, xprt, timeout);
+
clnt->cl_rtt = &clnt->cl_rtt_default;
rpc_init_rtt(&clnt->cl_rtt_default, clnt->cl_timeout->to_initval);
@@ -601,6 +620,80 @@ rpc_clone_client_set_auth(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
}
EXPORT_SYMBOL_GPL(rpc_clone_client_set_auth);
+/**
+ * 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 RPC tasks by using some form of locking.
+ *
+ * Returns zero if "clnt" is now using the new xprt. Otherwise a
+ * negative errno is returned, and "clnt" continues to use the old
+ * xprt.
+ */
+int rpc_switch_client_transport(struct rpc_clnt *clnt,
+ struct xprt_create *args,
+ const struct rpc_timeout *timeout)
+{
+ const struct rpc_timeout *old_timeo;
+ rpc_authflavor_t pseudoflavor;
+ struct rpc_xprt *xprt, *old;
+ struct rpc_clnt *parent;
+ int err;
+
+ xprt = xprt_create_transport(args);
+ if (IS_ERR(xprt)) {
+ dprintk("RPC: failed to create new xprt for clnt %p\n",
+ clnt);
+ return PTR_ERR(xprt);
+ }
+
+ pseudoflavor = clnt->cl_auth->au_flavor;
+
+ old_timeo = clnt->cl_timeout;
+ old = rpc_clnt_set_transport(clnt, xprt, timeout);
+
+ rpc_unregister_client(clnt);
+ __rpc_clnt_remove_pipedir(clnt);
+
+ /*
+ * A new transport was created. "clnt" therefore
+ * becomes the root of a new cl_parent tree. clnt's
+ * children, if it has any, still point to the old xprt.
+ */
+ parent = clnt->cl_parent;
+ clnt->cl_parent = clnt;
+
+ /*
+ * The old rpc_auth cache cannot be re-used. GSS
+ * contexts in particular are between a single
+ * client and server.
+ */
+ err = rpc_client_register(clnt, pseudoflavor, NULL);
+ if (err)
+ goto out_revert;
+
+ synchronize_rcu();
+ if (parent != clnt)
+ rpc_release_client(parent);
+ xprt_put(old);
+ dprintk("RPC: replaced xprt for clnt %p\n", clnt);
+ return 0;
+
+out_revert:
+ rpc_clnt_set_transport(clnt, old, old_timeo);
+ clnt->cl_parent = parent;
+ rpc_client_register(clnt, pseudoflavor, NULL);
+ xprt_put(xprt);
+ dprintk("RPC: failed to switch xprt for clnt %p\n", clnt);
+ return err;
+}
+EXPORT_SYMBOL_GPL(rpc_switch_client_transport);
+
/*
* Kill all tasks for the given client.
* XXX: kill their descendants as well?
--
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