SUNRPC: subscribe RPC clients to pipefs notifications

This patch subscribes RPC clients to RPC pipefs notifications. RPC clients
notifier block is registering with pipefs initialization during SUNRPC module
init.
This notifier callback is responsible for RPC client PipeFS directory and GSS
pipes creation. For pipes creation and destruction two additional callbacks
were added to struct rpc_authops.
Note that no locking required in notifier callback because PipeFS superblock
pointer is passed as an argument from it's creation or destruction routine and
thus we can be sure about it's validity.

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

1 files changed, 68 insertions, 1 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 90e82c5daeb6..417074500592 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -98,8 +98,11 @@ static void rpc_unregister_client(struct rpc_clnt *clnt)
 
 static void __rpc_clnt_remove_pipedir(struct rpc_clnt *clnt)
 {
-	if (clnt->cl_path.dentry)
+	if (clnt->cl_path.dentry) {
+		if (clnt->cl_auth && clnt->cl_auth->au_ops->pipes_destroy)
+			clnt->cl_auth->au_ops->pipes_destroy(clnt->cl_auth);
 		rpc_remove_client_dir(clnt->cl_path.dentry);
+	}
 	clnt->cl_path.dentry = NULL;
 }
 
@@ -181,6 +184,70 @@ rpc_setup_pipedir(struct rpc_clnt *clnt, char *dir_name)
 	return 0;
 }
 
+static int __rpc_pipefs_event(struct rpc_clnt *clnt, unsigned long event,
+				struct super_block *sb)
+{
+	struct dentry *dentry;
+	int err = 0;
+
+	switch (event) {
+	case RPC_PIPEFS_MOUNT:
+		if (clnt->cl_program->pipe_dir_name == NULL)
+			break;
+		dentry = rpc_setup_pipedir_sb(sb, clnt,
+					      clnt->cl_program->pipe_dir_name);
+		BUG_ON(dentry == NULL);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+		clnt->cl_path.dentry = dentry;
+		if (clnt->cl_auth->au_ops->pipes_create) {
+			err = clnt->cl_auth->au_ops->pipes_create(clnt->cl_auth);
+			if (err)
+				__rpc_clnt_remove_pipedir(clnt);
+		}
+		break;
+	case RPC_PIPEFS_UMOUNT:
+		__rpc_clnt_remove_pipedir(clnt);
+		break;
+	default:
+		printk(KERN_ERR "%s: unknown event: %ld\n", __func__, event);
+		return -ENOTSUPP;
+	}
+	return err;
+}
+
+static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
+			    void *ptr)
+{
+	struct super_block *sb = ptr;
+	struct rpc_clnt *clnt;
+	int error = 0;
+	struct sunrpc_net *sn = net_generic(sb->s_fs_info, sunrpc_net_id);
+
+	spin_lock(&sn->rpc_client_lock);
+	list_for_each_entry(clnt, &sn->all_clients, cl_clients) {
+		error = __rpc_pipefs_event(clnt, event, sb);
+		if (error)
+			break;
+	}
+	spin_unlock(&sn->rpc_client_lock);
+	return error;
+}
+
+static struct notifier_block rpc_clients_block = {
+	.notifier_call	= rpc_pipefs_event,
+};
+
+int rpc_clients_notifier_register(void)
+{
+	return rpc_pipefs_notifier_register(&rpc_clients_block);
+}
+
+void rpc_clients_notifier_unregister(void)
+{
+	return rpc_pipefs_notifier_unregister(&rpc_clients_block);
+}
+
 static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, struct rpc_xprt *xprt)
 {
 	struct rpc_program	*program = args->program;