// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2012 Red Hat, Inc.
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* Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
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*/
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#include <linux/ctype.h>
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#include <linux/efi.h>
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#include <linux/fs.h>
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#include <linux/fs_context.h>
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#include <linux/module.h>
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#include <linux/pagemap.h>
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#include <linux/ucs2_string.h>
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#include <linux/slab.h>
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#include <linux/magic.h>
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#include "internal.h"
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LIST_HEAD(efivarfs_list);
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static void efivarfs_evict_inode(struct inode *inode)
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{
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clear_inode(inode);
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}
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static const struct super_operations efivarfs_ops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.evict_inode = efivarfs_evict_inode,
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};
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/*
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* Compare two efivarfs file names.
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*
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* An efivarfs filename is composed of two parts,
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*
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* 1. A case-sensitive variable name
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* 2. A case-insensitive GUID
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*
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* So we need to perform a case-sensitive match on part 1 and a
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* case-insensitive match on part 2.
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*/
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static int efivarfs_d_compare(const struct dentry *dentry,
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unsigned int len, const char *str,
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const struct qstr *name)
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{
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int guid = len - EFI_VARIABLE_GUID_LEN;
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if (name->len != len)
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return 1;
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/* Case-sensitive compare for the variable name */
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if (memcmp(str, name->name, guid))
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return 1;
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/* Case-insensitive compare for the GUID */
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return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
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}
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static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
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{
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unsigned long hash = init_name_hash(dentry);
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const unsigned char *s = qstr->name;
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unsigned int len = qstr->len;
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if (!efivarfs_valid_name(s, len))
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return -EINVAL;
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while (len-- > EFI_VARIABLE_GUID_LEN)
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hash = partial_name_hash(*s++, hash);
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/* GUID is case-insensitive. */
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while (len--)
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hash = partial_name_hash(tolower(*s++), hash);
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qstr->hash = end_name_hash(hash);
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return 0;
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}
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static const struct dentry_operations efivarfs_d_ops = {
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.d_compare = efivarfs_d_compare,
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.d_hash = efivarfs_d_hash,
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.d_delete = always_delete_dentry,
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};
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static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
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{
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struct dentry *d;
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struct qstr q;
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int err;
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q.name = name;
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q.len = strlen(name);
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err = efivarfs_d_hash(parent, &q);
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if (err)
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return ERR_PTR(err);
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d = d_alloc(parent, &q);
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if (d)
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return d;
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return ERR_PTR(-ENOMEM);
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}
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static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
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unsigned long name_size, void *data)
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{
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struct super_block *sb = (struct super_block *)data;
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struct efivar_entry *entry;
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struct inode *inode = NULL;
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struct dentry *dentry, *root = sb->s_root;
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unsigned long size = 0;
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char *name;
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int len;
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int err = -ENOMEM;
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bool is_removable = false;
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entry = kzalloc(sizeof(*entry), GFP_KERNEL);
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if (!entry)
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return err;
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memcpy(entry->var.VariableName, name16, name_size);
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memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
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len = ucs2_utf8size(entry->var.VariableName);
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/* name, plus '-', plus GUID, plus NUL*/
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name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
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if (!name)
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goto fail;
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ucs2_as_utf8(name, entry->var.VariableName, len);
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if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
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is_removable = true;
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name[len] = '-';
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efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
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name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
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/* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
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strreplace(name, '/', '!');
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inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
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is_removable);
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if (!inode)
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goto fail_name;
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dentry = efivarfs_alloc_dentry(root, name);
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if (IS_ERR(dentry)) {
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err = PTR_ERR(dentry);
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goto fail_inode;
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}
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efivar_entry_size(entry, &size);
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err = efivar_entry_add(entry, &efivarfs_list);
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if (err)
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goto fail_inode;
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/* copied by the above to local storage in the dentry. */
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kfree(name);
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inode_lock(inode);
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inode->i_private = entry;
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i_size_write(inode, size + sizeof(entry->var.Attributes));
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inode_unlock(inode);
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d_add(dentry, inode);
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return 0;
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fail_inode:
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iput(inode);
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fail_name:
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kfree(name);
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fail:
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kfree(entry);
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return err;
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}
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static int efivarfs_destroy(struct efivar_entry *entry, void *data)
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{
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int err = efivar_entry_remove(entry);
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if (err)
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return err;
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kfree(entry);
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return 0;
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}
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static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
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{
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struct inode *inode = NULL;
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struct dentry *root;
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int err;
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sb->s_maxbytes = MAX_LFS_FILESIZE;
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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 = EFIVARFS_MAGIC;
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sb->s_op = &efivarfs_ops;
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sb->s_d_op = &efivarfs_d_ops;
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sb->s_time_gran = 1;
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if (!efivar_supports_writes())
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sb->s_flags |= SB_RDONLY;
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inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
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if (!inode)
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return -ENOMEM;
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inode->i_op = &efivarfs_dir_inode_operations;
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root = d_make_root(inode);
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sb->s_root = root;
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if (!root)
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return -ENOMEM;
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INIT_LIST_HEAD(&efivarfs_list);
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err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
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if (err)
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__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
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return err;
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}
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static int efivarfs_get_tree(struct fs_context *fc)
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{
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return get_tree_single(fc, efivarfs_fill_super);
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}
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static const struct fs_context_operations efivarfs_context_ops = {
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.get_tree = efivarfs_get_tree,
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};
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static int efivarfs_init_fs_context(struct fs_context *fc)
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{
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fc->ops = &efivarfs_context_ops;
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return 0;
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}
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static void efivarfs_kill_sb(struct super_block *sb)
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{
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kill_litter_super(sb);
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/* Remove all entries and destroy */
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__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
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}
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static struct file_system_type efivarfs_type = {
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.owner = THIS_MODULE,
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.name = "efivarfs",
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.init_fs_context = efivarfs_init_fs_context,
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.kill_sb = efivarfs_kill_sb,
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};
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static __init int efivarfs_init(void)
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{
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if (!efivars_kobject())
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return -ENODEV;
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return register_filesystem(&efivarfs_type);
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}
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static __exit void efivarfs_exit(void)
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{
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unregister_filesystem(&efivarfs_type);
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}
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MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
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MODULE_DESCRIPTION("EFI Variable Filesystem");
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MODULE_LICENSE("GPL");
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MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
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MODULE_ALIAS_FS("efivarfs");
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module_init(efivarfs_init);
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module_exit(efivarfs_exit);
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