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SUNRPC: Add a helper to switch the transport of an rpc_clnt

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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@netapp.com>
[ cel: forward ported to 3.12 ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2013-10-17 14:12:23 -04:00
parent d746e54522
commit 40b00b6b17
2 changed files with 104 additions and 7 deletions
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4
include/linux/sunrpc/clnt.h
View File

@ -136,6 +136,10 @@ 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 *);

107
net/sunrpc/clnt.c
View File

@ -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?