// SPDX-License-Identifier: GPL-2.0-or-later /* * 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);