/* * fs/sysfs/symlink.c - operations for initializing and mounting sysfs * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007 Tejun Heo <teheo@suse.de> * * This file is released under the GPLv2. * * Please see Documentation/filesystems/sysfs.txt for more information. */ #define DEBUG #include <linux/fs.h>#include <linux/magic.h>#include <linux/mount.h>#include <linux/init.h>#include <linux/user_namespace.h> #include "sysfs.h" static struct kernfs_root *sysfs_root;struct kernfs_node *sysfs_root_kn; static struct dentry *sysfs_mount(struct file_system_type *fs_type,	int flags, const char *dev_name, void *data){	struct dentry *root;	void *ns;	bool new_sb; 	if (!(flags & MS_KERNMOUNT)) {		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))			return ERR_PTR(-EPERM);	} 	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);	root = kernfs_mount_ns(fs_type, flags, sysfs_root,				SYSFS_MAGIC, &new_sb, ns);	if (IS_ERR(root) || !new_sb)		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);	else if (new_sb)		root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE; 	return root;} static void sysfs_kill_sb(struct super_block *sb){	void *ns = (void *)kernfs_super_ns(sb); 	kernfs_kill_sb(sb);	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);} static struct file_system_type sysfs_fs_type = {	.name		= "sysfs",	.mount		= sysfs_mount,	.kill_sb	= sysfs_kill_sb,	.fs_flags	= FS_USERNS_MOUNT,}; int __init sysfs_init(void){	int err; 	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,					NULL);	if (IS_ERR(sysfs_root))		return PTR_ERR(sysfs_root); 	sysfs_root_kn = sysfs_root->kn; 	err = register_filesystem(&sysfs_fs_type);	if (err) {		kernfs_destroy_root(sysfs_root);		return err;	} 	return 0;}