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/*
* 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/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include "sysfs.h"
struct kmem_cache *sysfs_dir_cachep;
static const struct super_operations sysfs_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.evict_inode = sysfs_evict_inode,
};
static struct kernfs_root *sysfs_root;
struct sysfs_dirent *sysfs_root_sd;
static int sysfs_fill_super(struct super_block *sb)
{
struct sysfs_super_info *info = sysfs_info(sb);
struct inode *inode;
struct dentry *root;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = SYSFS_MAGIC;
sb->s_op = &sysfs_ops;
sb->s_time_gran = 1;
/* get root inode, initialize and unlock it */
mutex_lock(&sysfs_mutex);
inode = sysfs_get_inode(sb, info->root->sd);
mutex_unlock(&sysfs_mutex);
if (!inode) {
pr_debug("sysfs: could not get root inode\n");
return -ENOMEM;
}
/* instantiate and link root dentry */
root = d_make_root(inode);
if (!root) {
pr_debug("%s: could not get root dentry!\n", __func__);
return -ENOMEM;
}
kernfs_get(info->root->sd);
root->d_fsdata = info->root->sd;
sb->s_root = root;
sb->s_d_op = &sysfs_dentry_ops;
return 0;
}
static int sysfs_test_super(struct super_block *sb, void *data)
{
struct sysfs_super_info *sb_info = sysfs_info(sb);
struct sysfs_super_info *info = data;
return sb_info->root == info->root && sb_info->ns == info->ns;
}
static int sysfs_set_super(struct super_block *sb, void *data)
{
int error;
error = set_anon_super(sb, data);
if (!error)
sb->s_fs_info = data;
return error;
}
static void free_sysfs_super_info(struct sysfs_super_info *info)
{
kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
kfree(info);
}
static struct dentry *sysfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
struct sysfs_super_info *info;
struct super_block *sb;
int error;
if (!(flags & MS_KERNMOUNT)) {
if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
return ERR_PTR(-EPERM);
if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
return ERR_PTR(-EPERM);
}
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return ERR_PTR(-ENOMEM);
info->root = sysfs_root;
info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
if (IS_ERR(sb) || sb->s_fs_info != info)
free_sysfs_super_info(info);
if (IS_ERR(sb))
return ERR_CAST(sb);
if (!sb->s_root) {
error = sysfs_fill_super(sb);
if (error) {
deactivate_locked_super(sb);
return ERR_PTR(error);
}
sb->s_flags |= MS_ACTIVE;
}
return dget(sb->s_root);
}
static void sysfs_kill_sb(struct super_block *sb)
{
struct sysfs_super_info *info = sysfs_info(sb);
struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
/*
* Remove the superblock from fs_supers/s_instances
* so we can't find it, before freeing sysfs_super_info.
*/
kill_anon_super(sb);
free_sysfs_super_info(info);
kernfs_put(root_sd);
}
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_dir_cachep = kmem_cache_create("sysfs_dir_cache",
sizeof(struct sysfs_dirent),
0, 0, NULL);
if (!sysfs_dir_cachep)
return -ENOMEM;
err = sysfs_inode_init();
if (err)
goto out_err;
sysfs_root = kernfs_create_root(NULL);
if (IS_ERR(sysfs_root)) {
err = PTR_ERR(sysfs_root);
goto out_err;
}
sysfs_root_sd = sysfs_root->sd;
err = register_filesystem(&sysfs_fs_type);
if (err)
goto out_destroy_root;
return 0;
out_destroy_root:
kernfs_destroy_root(sysfs_root);
out_err:
kmem_cache_destroy(sysfs_dir_cachep);
sysfs_dir_cachep = NULL;
return err;
}
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