NFS: handle blocklayout pipe PipeFS dentry by network namespace aware routines

This patch makes blocklayout pipe dentry allocated and destroyed in network
namespace context by PipeFS network namespace aware routines.
Network namespace context is obtained from nfs_client structure.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/blocklayout/blocklayout.c

@@ -1025,10 +1025,55 @@ static const struct rpc_pipe_ops bl_upcall_ops = {
 	.destroy_msg	= bl_pipe_destroy_msg,
 };
 
+static struct dentry *nfs4blocklayout_register_sb(struct super_block *sb,
+					    struct rpc_pipe *pipe)
+{
+	struct dentry *dir, *dentry;
+
+	dir = rpc_d_lookup_sb(sb, NFS_PIPE_DIRNAME);
+	if (dir == NULL)
+		return ERR_PTR(-ENOENT);
+	dentry = rpc_mkpipe_dentry(dir, "blocklayout", NULL, pipe);
+	dput(dir);
+	return dentry;
+}
+
+static void nfs4blocklayout_unregister_sb(struct super_block *sb,
+					  struct rpc_pipe *pipe)
+{
+	if (pipe->dentry)
+		rpc_unlink(pipe->dentry);
+}
+
+static struct dentry *nfs4blocklayout_register_net(struct net *net,
+						   struct rpc_pipe *pipe)
+{
+	struct super_block *pipefs_sb;
+	struct dentry *dentry;
+
+	pipefs_sb = rpc_get_sb_net(net);
+	if (!pipefs_sb)
+		return ERR_PTR(-ENOENT);
+	dentry = nfs4blocklayout_register_sb(pipefs_sb, pipe);
+	rpc_put_sb_net(net);
+	return dentry;
+}
+
+static void nfs4blocklayout_unregister_net(struct net *net,
+					   struct rpc_pipe *pipe)
+{
+	struct super_block *pipefs_sb;
+
+	pipefs_sb = rpc_get_sb_net(net);
+	if (pipefs_sb) {
+		nfs4blocklayout_unregister_sb(pipefs_sb, pipe);
+		rpc_put_sb_net(net);
+	}
+}
+
 static int __init nfs4blocklayout_init(void)
 {
 	struct vfsmount *mnt;
-	struct path path;
 	int ret;
 
 	dprintk("%s: NFSv4 Block Layout Driver Registering...\n", __func__);
@@ -1044,21 +1089,13 @@ static int __init nfs4blocklayout_init(void)
 		ret = PTR_ERR(mnt);
 		goto out_remove;
 	}
-
-	ret = vfs_path_lookup(mnt->mnt_root,
-			      mnt,
-			      NFS_PIPE_DIRNAME, 0, &path);
-	if (ret)
-		goto out_putrpc;
-
 	bl_device_pipe = rpc_mkpipe_data(&bl_upcall_ops, 0);
-	path_put(&path);
 	if (IS_ERR(bl_device_pipe)) {
 		ret = PTR_ERR(bl_device_pipe);
 		goto out_putrpc;
 	}
-	bl_device_pipe->dentry = rpc_mkpipe_dentry(path.dentry, "blocklayout",
-						   NULL, bl_device_pipe);
+	bl_device_pipe->dentry = nfs4blocklayout_register_net(&init_net,
+							      bl_device_pipe);
 	if (IS_ERR(bl_device_pipe->dentry)) {
 		ret = PTR_ERR(bl_device_pipe->dentry);
 		goto out_destroy_pipe;
@@ -1081,7 +1118,7 @@ static void __exit nfs4blocklayout_exit(void)
 	       __func__);
 
 	pnfs_unregister_layoutdriver(&blocklayout_type);
-	rpc_unlink(bl_device_pipe->dentry);
+	nfs4blocklayout_unregister_net(&init_net, bl_device_pipe);
 	rpc_destroy_pipe_data(bl_device_pipe);
 	rpc_put_mount();
 }