[PATCH 11/11] SUNRPC: sysctl table for rpc_debug introduced

[Stanislav Kinsbursky <skinsbursky@parallels.com>]

This patch provides showing of pending RPC tasks for right namespace in case of
write oparation to "rpc_debug" sysctl.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>

---
 include/linux/sunrpc/sched.h |    1 
 net/sunrpc/netns.h           |    1 
 net/sunrpc/sysctl.c          |   87 +++++++++++++++++++++++++++++++++++++-----
 3 files changed, 77 insertions(+), 12 deletions(-)

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index b16243a..02f5fce 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -244,7 +244,6 @@ int		rpciod_up(void);
 void		rpciod_down(void);
 int		__rpc_wait_for_completion_task(struct rpc_task *task, int (*)(void *));
 #ifdef RPC_DEBUG
-struct net;
 void		rpc_show_tasks(struct net *);
 #endif
 int		rpc_init_mempool(void);
diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index 23d110d..0926705 100644
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -16,6 +16,7 @@ struct sunrpc_net {
 	struct ctl_table_set sysctls;
 	struct ctl_table_header *debug_ctl_header;
 	struct ctl_table_header *xs_tunables_header;
+	struct ctl_table_header *rpc_debug_ctl_header;
 #endif
 	unsigned int xprt_udp_slot_table_entries;
 	unsigned int xprt_tcp_slot_table_entries;
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 224b075..52f6fb5 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -44,6 +44,15 @@ EXPORT_SYMBOL_GPL(nlm_debug);
 
 static ctl_table		debug_table[];
 
+static ctl_table rpc_debug_table[] = {
+	{
+		.procname	= "rpc_debug",
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+	},
+	{ }
+};
+
 struct ctl_path sunrpc_path[] = {
 	{ .procname = "sunrpc", },
 	{ },
@@ -73,6 +82,48 @@ struct ctl_table_header *register_sunrpc_sysctl(struct net *net,
 }
 EXPORT_SYMBOL_GPL(register_sunrpc_sysctl);
 
+static int proc_rpcdebug(ctl_table *table, int write,
+			 void __user *buffer, size_t *lenp, loff_t *ppos);
+
+static int register_rpc_debug_table(struct net *net)
+{
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+	struct ctl_table *table;
+
+	table = rpc_debug_table;
+	if (!net_eq(net, &init_net)) {
+		table = kmemdup(rpc_debug_table, sizeof(rpc_debug_table),
+				GFP_KERNEL);
+		if (table == NULL)
+			goto err_alloc;
+	}
+	table[0].data = net;
+	table[0].proc_handler = proc_rpcdebug;
+
+	sn->rpc_debug_ctl_header = register_sunrpc_sysctl(net, table);
+	if (sn->rpc_debug_ctl_header == NULL)
+		goto err_reg;
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static void unregister_rpc_debug_table(struct net *net)
+{
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+	struct ctl_table *table;
+
+	table = sn->rpc_debug_ctl_header->ctl_table_arg;
+	unregister_sysctl_table(sn->rpc_debug_ctl_header);
+	sn->rpc_debug_ctl_header = NULL;
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
+
 int debug_sysctl_init(struct net *net)
 {
 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
@@ -80,14 +131,23 @@ int debug_sysctl_init(struct net *net)
 	setup_sysctl_set(&sn->sysctls, NULL, NULL);
 	sn->debug_ctl_header = register_sunrpc_sysctl(net, debug_table);
 	if (sn->debug_ctl_header == NULL)
-		return -ENOMEM;
+		goto err_debug;
+	if (register_rpc_debug_table(net) < 0)
+		goto err_rpc_debug;
 	return 0;
+
+err_rpc_debug:
+	unregister_sysctl_table(sn->debug_ctl_header);
+	sn->debug_ctl_header = NULL;
+err_debug:
+	return -ENOMEM;
 }
 
 void debug_sysctl_exit(struct net *net)
 {
 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 
+	unregister_rpc_debug_table(net);
 	unregister_sysctl_table(sn->debug_ctl_header);
 	sn->debug_ctl_header = NULL;
 	WARN_ON(!list_empty(&sn->sysctls.list));
@@ -158,9 +218,6 @@ proc_dodebug(ctl_table *table, int write,
 			left--, s++;
 		if (net_eq(current->nsproxy->net_ns, &init_net))
 			*(unsigned int *) table->data = value;
-		/* Display the RPC tasks on writing to rpc_debug */
-		if (strcmp(table->procname, "rpc_debug") == 0)
-			rpc_show_tasks(&init_net);
 	} else {
 		if (!access_ok(VERIFY_WRITE, buffer, left))
 			return -EFAULT;
@@ -183,15 +240,23 @@ done:
 }
 
 
+static int
+proc_rpcdebug(ctl_table *table, int write,
+				void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int err;
+	struct ctl_table tmp = *table;
+
+	tmp.data = &rpc_debug;
+	err = proc_dodebug(&tmp, write, buffer, lenp, ppos);
+	if (!err && write)
+		/* Display the RPC tasks on writing to rpc_debug */
+		rpc_show_tasks(table->data);
+	return err;
+}
+
 static ctl_table debug_table[] = {
 	{
-		.procname	= "rpc_debug",
-		.data		= &rpc_debug,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dodebug
-	},
-	{
 		.procname	= "nfs_debug",
 		.data		= &nfs_debug,
 		.maxlen		= sizeof(int),