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, 13 insertions, 6 deletions

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 6dd8b96..910de41 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -937,7 +937,7 @@ struct dentry *rpc_create_client_dir(struct dentry *dentry,
 
 /**
  * rpc_remove_client_dir - Remove a directory created with rpc_create_client_dir()
- * @dentry: directory to remove
+ * @clnt: rpc client
  */
 int rpc_remove_client_dir(struct dentry *dentry)
 {
@@ -1188,17 +1188,24 @@ int register_rpc_pipefs(void)
 				init_once);
 	if (!rpc_inode_cachep)
 		return -ENOMEM;
+	err = rpc_clients_notifier_register();
+	if (err)
+		goto err_notifier;
 	err = register_filesystem(&rpc_pipe_fs_type);
-	if (err) {
-		kmem_cache_destroy(rpc_inode_cachep);
-		return err;
-	}
-
+	if (err)
+		goto err_register;
 	return 0;
+
+err_register:
+	rpc_clients_notifier_unregister();
+err_notifier:
+	kmem_cache_destroy(rpc_inode_cachep);
+	return err;
 }
 
 void unregister_rpc_pipefs(void)
 {
+	rpc_clients_notifier_unregister();
 	kmem_cache_destroy(rpc_inode_cachep);
 	unregister_filesystem(&rpc_pipe_fs_type);
 }