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