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// SPDX-License-Identifier: GPL-2.0-or-later
/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* mount.c - operations for initializing and mounting configfs.
*
* Based on sysfs:
* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
*
* configfs Copyright (C) 2005 Oracle. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/fs_context.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/configfs.h>
#include "configfs_internal.h"
/* Random magic number */
#define CONFIGFS_MAGIC 0x62656570
static struct vfsmount *configfs_mount = NULL;
struct kmem_cache *configfs_dir_cachep;
static int configfs_mnt_count = 0;
static void configfs_free_inode(struct inode *inode)
{
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
free_inode_nonrcu(inode);
}
static const struct super_operations configfs_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.free_inode = configfs_free_inode,
};
static struct config_group configfs_root_group = {
.cg_item = {
.ci_namebuf = "root",
.ci_name = configfs_root_group.cg_item.ci_namebuf,
},
};
int configfs_is_root(struct config_item *item)
{
return item == &configfs_root_group.cg_item;
}
static struct configfs_dirent configfs_root = {
.s_sibling = LIST_HEAD_INIT(configfs_root.s_sibling),
.s_children = LIST_HEAD_INIT(configfs_root.s_children),
.s_element = &configfs_root_group.cg_item,
.s_type = CONFIGFS_ROOT,
.s_iattr = NULL,
};
static int configfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct inode *inode;
struct dentry *root;
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_SHIFT;
sb->s_magic = CONFIGFS_MAGIC;
sb->s_op = &configfs_ops;
sb->s_time_gran = 1;
inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
&configfs_root, sb);
if (inode) {
inode->i_op = &configfs_root_inode_operations;
inode->i_fop = &configfs_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
} else {
pr_debug("could not get root inode\n");
return -ENOMEM;
}
root = d_make_root(inode);
if (!root) {
pr_debug("%s: could not get root dentry!\n",__func__);
return -ENOMEM;
}
config_group_init(&configfs_root_group);
configfs_root_group.cg_item.ci_dentry = root;
root->d_fsdata = &configfs_root;
sb->s_root = root;
sb->s_d_op = &configfs_dentry_ops; /* the rest get that */
return 0;
}
static int configfs_get_tree(struct fs_context *fc)
{
return get_tree_single(fc, configfs_fill_super);
}
static const struct fs_context_operations configfs_context_ops = {
.get_tree = configfs_get_tree,
};
static int configfs_init_fs_context(struct fs_context *fc)
{
fc->ops = &configfs_context_ops;
return 0;
}
static struct file_system_type configfs_fs_type = {
.owner = THIS_MODULE,
.name = "configfs",
.init_fs_context = configfs_init_fs_context,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("configfs");
struct dentry *configfs_pin_fs(void)
{
int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
&configfs_mnt_count);
return err ? ERR_PTR(err) : configfs_mount->mnt_root;
}
void configfs_release_fs(void)
{
simple_release_fs(&configfs_mount, &configfs_mnt_count);
}
static int __init configfs_init(void)
{
int err = -ENOMEM;
configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
sizeof(struct configfs_dirent),
0, 0, NULL);
if (!configfs_dir_cachep)
goto out;
err = sysfs_create_mount_point(kernel_kobj, "config");
if (err)
goto out2;
err = register_filesystem(&configfs_fs_type);
if (err)
goto out3;
return 0;
out3:
pr_err("Unable to register filesystem!\n");
sysfs_remove_mount_point(kernel_kobj, "config");
out2:
kmem_cache_destroy(configfs_dir_cachep);
configfs_dir_cachep = NULL;
out:
return err;
}
static void __exit configfs_exit(void)
{
unregister_filesystem(&configfs_fs_type);
sysfs_remove_mount_point(kernel_kobj, "config");
kmem_cache_destroy(configfs_dir_cachep);
configfs_dir_cachep = NULL;
}
MODULE_AUTHOR("Oracle");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.0.2");
MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
core_initcall(configfs_init);
module_exit(configfs_exit);
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