commit cb7323fffa85df37161f4d3be45e1f787808309c
author Stanislav Kinsbursky <skinsbursky@parallels.com> Tue Sep 18 13:37:23 2012 +0400
committer Trond Myklebust <Trond.Myklebust@netapp.com> Mon Oct 01 15:27:43 2012 -0700
tree e981d8fb5bc7d10a8118a9d2e0805a4c5fbd4545
parent 303a7ce92064c285a04c870f2dc0192fdb2968cb

lockd: create and use per-net NSM RPC clients on MON/UNMON requests

NSM RPC client can be required on NFSv3 umount, when child reaper is dying
(and destroying it's mount namespace). It means, that current nsproxy is set
to NULL already, but creation of RPC client requires UTS namespace for gaining
hostname string.

This patch creates reference-counted per-net NSM client on first monitor
request and destroys it after last unmonitor request.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/mon.c

diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index e0bc36e..e4fb3ba 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -7,7 +7,6 @@
  */
 
 #include <linux/types.h>
-#include <linux/utsname.h>
 #include <linux/kernel.h>
 #include <linux/ktime.h>
 #include <linux/slab.h>
@@ -86,7 +85,7 @@
 	return rpc_create(&args);
 }
 
-__maybe_unused static struct rpc_clnt *nsm_client_get(struct net *net)
+static struct rpc_clnt *nsm_client_get(struct net *net)
 {
 	static DEFINE_MUTEX(nsm_create_mutex);
 	struct rpc_clnt	*clnt;
@@ -113,7 +112,7 @@
 	return clnt;
 }
 
-__maybe_unused static void nsm_client_put(struct net *net)
+static void nsm_client_put(struct net *net)
 {
 	struct lockd_net *ln = net_generic(net, lockd_net_id);
 	struct rpc_clnt	*clnt = ln->nsm_clnt;
@@ -132,9 +131,8 @@
 }
 
 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
-			 struct net *net)
+			 struct rpc_clnt *clnt)
 {
-	struct rpc_clnt	*clnt;
 	int		status;
 	struct nsm_args args = {
 		.priv		= &nsm->sm_priv,
@@ -142,20 +140,14 @@
 		.vers		= 3,
 		.proc		= NLMPROC_NSM_NOTIFY,
 		.mon_name	= nsm->sm_mon_name,
-		.nodename	= utsname()->nodename,
+		.nodename	= clnt->cl_nodename,
 	};
 	struct rpc_message msg = {
 		.rpc_argp	= &args,
 		.rpc_resp	= res,
 	};
 
-	clnt = nsm_create(net);
-	if (IS_ERR(clnt)) {
-		status = PTR_ERR(clnt);
-		dprintk("lockd: failed to create NSM upcall transport, "
-				"status=%d\n", status);
-		goto out;
-	}
+	BUG_ON(clnt == NULL);
 
 	memset(res, 0, sizeof(*res));
 
@@ -166,8 +158,6 @@
 				status);
 	else
 		status = 0;
-	rpc_shutdown_client(clnt);
- out:
 	return status;
 }
 
@@ -187,6 +177,7 @@
 	struct nsm_handle *nsm = host->h_nsmhandle;
 	struct nsm_res	res;
 	int		status;
+	struct rpc_clnt *clnt;
 
 	dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 
@@ -199,7 +190,15 @@
 	 */
 	nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 
-	status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host->net);
+	clnt = nsm_client_get(host->net);
+	if (IS_ERR(clnt)) {
+		status = PTR_ERR(clnt);
+		dprintk("lockd: failed to create NSM upcall transport, "
+				"status=%d, net=%p\n", status, host->net);
+		return status;
+	}
+
+	status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, clnt);
 	if (unlikely(res.status != 0))
 		status = -EIO;
 	if (unlikely(status < 0)) {
@@ -231,9 +230,11 @@
 
 	if (atomic_read(&nsm->sm_count) == 1
 	 && nsm->sm_monitored && !nsm->sm_sticky) {
+		struct lockd_net *ln = net_generic(host->net, lockd_net_id);
+
 		dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 
-		status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host->net);
+		status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, ln->nsm_clnt);
 		if (res.status != 0)
 			status = -EIO;
 		if (status < 0)
@@ -241,6 +242,8 @@
 					nsm->sm_name);
 		else
 			nsm->sm_monitored = 0;
+
+		nsm_client_put(host->net);
 	}
 }