From 996bc4f405d37ffd88c9b830202ee47fc7a6c449 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Thu, 24 Jan 2019 16:10:46 -0500
Subject: NFS: Create a root NFS directory in /sys/fs/nfs

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/Makefile |  3 ++-
 fs/nfs/inode.c  |  8 +++++++
 fs/nfs/sysfs.c  | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfs/sysfs.h  | 15 +++++++++++++
 4 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 fs/nfs/sysfs.c
 create mode 100644 fs/nfs/sysfs.h

diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index c587e3c4c6a6..34cdeaecccf6 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -8,7 +8,8 @@ obj-$(CONFIG_NFS_FS) += nfs.o
 CFLAGS_nfstrace.o += -I$(src)
 nfs-y 			:= client.o dir.o file.o getroot.o inode.o super.o \
 			   io.o direct.o pagelist.o read.o symlink.o unlink.o \
-			   write.o namespace.o mount_clnt.o nfstrace.o export.o
+			   write.o namespace.o mount_clnt.o nfstrace.o \
+			   export.o sysfs.o
 nfs-$(CONFIG_ROOT_NFS)	+= nfsroot.o
 nfs-$(CONFIG_SYSCTL)	+= sysctl.o
 nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 53777813ca95..8dba56491de2 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -51,6 +51,7 @@
 #include "pnfs.h"
 #include "nfs.h"
 #include "netns.h"
+#include "sysfs.h"
 
 #include "nfstrace.h"
 
@@ -2182,6 +2183,10 @@ static int __init init_nfs_fs(void)
 {
 	int err;
 
+	err = nfs_sysfs_init();
+	if (err < 0)
+		goto out10;
+
 	err = register_pernet_subsys(&nfs_net_ops);
 	if (err < 0)
 		goto out9;
@@ -2245,6 +2250,8 @@ out7:
 out8:
 	unregister_pernet_subsys(&nfs_net_ops);
 out9:
+	nfs_sysfs_exit();
+out10:
 	return err;
 }
 
@@ -2261,6 +2268,7 @@ static void __exit exit_nfs_fs(void)
 	unregister_nfs_fs();
 	nfs_fs_proc_exit();
 	nfsiod_stop();
+	nfs_sysfs_exit();
 }
 
 /* Not quite true; I just maintain it */
diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
new file mode 100644
index 000000000000..7070711ff6c5
--- /dev/null
+++ b/fs/nfs/sysfs.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Hammerspace Inc
+ */
+
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+
+#include "sysfs.h"
+
+struct kobject *nfs_client_kobj;
+static struct kset *nfs_client_kset;
+
+static void nfs_netns_object_release(struct kobject *kobj)
+{
+	kfree(kobj);
+}
+
+static const struct kobj_ns_type_operations *nfs_netns_object_child_ns_type(
+		struct kobject *kobj)
+{
+	return &net_ns_type_operations;
+}
+
+static struct kobj_type nfs_netns_object_type = {
+	.release = nfs_netns_object_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.child_ns_type = nfs_netns_object_child_ns_type,
+};
+
+static struct kobject *nfs_netns_object_alloc(const char *name,
+		struct kset *kset, struct kobject *parent)
+{
+	struct kobject *kobj;
+
+	kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
+	if (kobj) {
+		kobj->kset = kset;
+		if (kobject_init_and_add(kobj, &nfs_netns_object_type,
+					parent, "%s", name) == 0)
+			return kobj;
+		kobject_put(kobj);
+	}
+	return NULL;
+}
+
+int nfs_sysfs_init(void)
+{
+	nfs_client_kset = kset_create_and_add("nfs", NULL, fs_kobj);
+	if (!nfs_client_kset)
+		return -ENOMEM;
+	nfs_client_kobj = nfs_netns_object_alloc("net", nfs_client_kset, NULL);
+	if  (!nfs_client_kobj) {
+		kset_unregister(nfs_client_kset);
+		nfs_client_kset = NULL;
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void nfs_sysfs_exit(void)
+{
+	kobject_put(nfs_client_kobj);
+	kset_unregister(nfs_client_kset);
+}
diff --git a/fs/nfs/sysfs.h b/fs/nfs/sysfs.h
new file mode 100644
index 000000000000..666f8db2ba92
--- /dev/null
+++ b/fs/nfs/sysfs.h
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Hammerspace Inc
+ */
+
+#ifndef __NFS_SYSFS_H
+#define __NFS_SYSFS_H
+
+
+extern struct kobject *nfs_client_kobj;
+
+extern int nfs_sysfs_init(void);
+extern void nfs_sysfs_exit(void);
+
+#endif
-- 
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