SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field
A migration event will replace the rpc_xprt used by an rpc_clnt. To
ensure this can be done safely, all references to cl_xprt must now use
a form of rcu_dereference().
Special care is taken with rpc_peeraddr2str(), which returns a pointer
to memory whose lifetime is the same as the rpc_xprt.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ cel: fix lockdep splats and layering violations ]
[ cel: forward ported to 3.4 ]
[ cel: remove rpc_max_reqs(), add rpc_net_ns() ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 1506adf..d038dc5 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1284,16 +1284,18 @@
int error;
if (clp->rpc_ops->version == 4) {
+ struct rpc_xprt *xprt;
+
+ xprt = rcu_dereference_raw(clp->cl_rpcclient->cl_xprt);
+
if (nfs4_has_session(clp)) {
- error = xprt_setup_backchannel(
- clp->cl_rpcclient->cl_xprt,
+ error = xprt_setup_backchannel(xprt,
NFS41_BC_MIN_CALLBACKS);
if (error < 0)
return error;
}
- error = nfs_callback_up(clp->cl_mvops->minor_version,
- clp->cl_rpcclient->cl_xprt);
+ error = nfs_callback_up(clp->cl_mvops->minor_version, xprt);
if (error < 0) {
dprintk("%s: failed to start callback. Error = %d\n",
__func__, error);
@@ -1678,7 +1680,7 @@
data->addrlen,
parent_client->cl_ipaddr,
data->authflavor,
- parent_server->client->cl_xprt->prot,
+ rpc_protocol(parent_server->client),
parent_server->client->cl_timeout,
parent_client->cl_mvops->minor_version,
parent_client->net);
@@ -1905,12 +1907,14 @@
if (clp->cl_cons_state != NFS_CS_READY)
return 0;
+ rcu_read_lock();
seq_printf(m, "v%u %s %s %3d %s\n",
clp->rpc_ops->version,
rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),
atomic_read(&clp->cl_count),
clp->cl_hostname);
+ rcu_read_unlock();
return 0;
}
@@ -1993,6 +1997,7 @@
(unsigned long long) server->fsid.major,
(unsigned long long) server->fsid.minor);
+ rcu_read_lock();
seq_printf(m, "v%u %s %s %-7s %-17s %s\n",
clp->rpc_ops->version,
rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
@@ -2000,6 +2005,7 @@
dev,
fsid,
nfs_server_fscache_state(server));
+ rcu_read_unlock();
return 0;
}