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278 lines
6.2 KiB
278 lines
6.2 KiB
// 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 <[email protected]> |
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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_ALIAS_FS("efivarfs"); |
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module_init(efivarfs_init); |
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module_exit(efivarfs_exit);
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