efivarfs: Move to fs/efivarfs

Now that efivarfs uses the efivar API, move it out of efivars.c and
into fs/efivarfs where it belongs. This move will eventually allow us
to enable the efivarfs code without having to also enable
CONFIG_EFI_VARS built, and vice versa.

Furthermore, things like,

    mount -t efivarfs none /sys/firmware/efi/efivars

will now work if efivarfs is built as a module without requiring the
use of MODULE_ALIAS(), which would have been necessary when the
efivarfs code was part of efivars.c.

Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Jeremy Kerr <jk@ozlabs.org>
Reviewed-by: Tom Gundersen <teg@jklm.no>
Tested-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 267 insertions, 0 deletions

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
new file mode 100644
index 000000000000..34c48f1fcdbc
--- /dev/null
+++ b/fs/efivarfs/super.c
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/ctype.h>
+#include <linux/efi.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+
+#include "internal.h"
+
+LIST_HEAD(efivarfs_list);
+
+static void efivarfs_evict_inode(struct inode *inode)
+{
+	clear_inode(inode);
+}
+
+static const struct super_operations efivarfs_ops = {
+	.statfs = simple_statfs,
+	.drop_inode = generic_delete_inode,
+	.evict_inode = efivarfs_evict_inode,
+	.show_options = generic_show_options,
+};
+
+static struct super_block *efivarfs_sb;
+
+/*
+ * Compare two efivarfs file names.
+ *
+ * An efivarfs filename is composed of two parts,
+ *
+ *	1. A case-sensitive variable name
+ *	2. A case-insensitive GUID
+ *
+ * So we need to perform a case-sensitive match on part 1 and a
+ * case-insensitive match on part 2.
+ */
+static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
+			      const struct dentry *dentry, const struct inode *inode,
+			      unsigned int len, const char *str,
+			      const struct qstr *name)
+{
+	int guid = len - EFI_VARIABLE_GUID_LEN;
+
+	if (name->len != len)
+		return 1;
+
+	/* Case-sensitive compare for the variable name */
+	if (memcmp(str, name->name, guid))
+		return 1;
+
+	/* Case-insensitive compare for the GUID */
+	return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
+}
+
+static int efivarfs_d_hash(const struct dentry *dentry,
+			   const struct inode *inode, struct qstr *qstr)
+{
+	unsigned long hash = init_name_hash();
+	const unsigned char *s = qstr->name;
+	unsigned int len = qstr->len;
+
+	if (!efivarfs_valid_name(s, len))
+		return -EINVAL;
+
+	while (len-- > EFI_VARIABLE_GUID_LEN)
+		hash = partial_name_hash(*s++, hash);
+
+	/* GUID is case-insensitive. */
+	while (len--)
+		hash = partial_name_hash(tolower(*s++), hash);
+
+	qstr->hash = end_name_hash(hash);
+	return 0;
+}
+
+/*
+ * Retaining negative dentries for an in-memory filesystem just wastes
+ * memory and lookup time: arrange for them to be deleted immediately.
+ */
+static int efivarfs_delete_dentry(const struct dentry *dentry)
+{
+	return 1;
+}
+
+static struct dentry_operations efivarfs_d_ops = {
+	.d_compare = efivarfs_d_compare,
+	.d_hash = efivarfs_d_hash,
+	.d_delete = efivarfs_delete_dentry,
+};
+
+static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
+{
+	struct dentry *d;
+	struct qstr q;
+	int err;
+
+	q.name = name;
+	q.len = strlen(name);
+
+	err = efivarfs_d_hash(NULL, NULL, &q);
+	if (err)
+		return ERR_PTR(err);
+
+	d = d_alloc(parent, &q);
+	if (d)
+		return d;
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
+			     unsigned long name_size, void *data)
+{
+	struct super_block *sb = (struct super_block *)data;
+	struct efivar_entry *entry;
+	struct inode *inode = NULL;
+	struct dentry *dentry, *root = sb->s_root;
+	unsigned long size = 0;
+	char *name;
+	int len, i;
+	int err = -ENOMEM;
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return err;
+
+	memcpy(entry->var.VariableName, name16, name_size);
+	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
+
+	len = utf16_strlen(entry->var.VariableName);
+
+	/* name, plus '-', plus GUID, plus NUL*/
+	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
+	if (!name)
+		goto fail;
+
+	for (i = 0; i < len; i++)
+		name[i] = entry->var.VariableName[i] & 0xFF;
+
+	name[len] = '-';
+
+	efi_guid_unparse(&entry->var.VendorGuid, name + len + 1);
+
+	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
+
+	inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0);
+	if (!inode)
+		goto fail_name;
+
+	dentry = efivarfs_alloc_dentry(root, name);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto fail_inode;
+	}
+
+	/* copied by the above to local storage in the dentry. */
+	kfree(name);
+
+	efivar_entry_size(entry, &size);
+	efivar_entry_add(entry, &efivarfs_list);
+
+	mutex_lock(&inode->i_mutex);
+	inode->i_private = entry;
+	i_size_write(inode, size + sizeof(entry->var.Attributes));
+	mutex_unlock(&inode->i_mutex);
+	d_add(dentry, inode);
+
+	return 0;
+
+fail_inode:
+	iput(inode);
+fail_name:
+	kfree(name);
+fail:
+	kfree(entry);
+	return err;
+}
+
+static int efivarfs_destroy(struct efivar_entry *entry, void *data)
+{
+	efivar_entry_remove(entry);
+	kfree(entry);
+	return 0;
+}
+
+static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode = NULL;
+	struct dentry *root;
+	int err;
+
+	efivarfs_sb = sb;
+
+	sb->s_maxbytes          = MAX_LFS_FILESIZE;
+	sb->s_blocksize         = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
+	sb->s_magic             = EFIVARFS_MAGIC;
+	sb->s_op                = &efivarfs_ops;
+	sb->s_d_op		= &efivarfs_d_ops;
+	sb->s_time_gran         = 1;
+
+	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
+	if (!inode)
+		return -ENOMEM;
+	inode->i_op = &efivarfs_dir_inode_operations;
+
+	root = d_make_root(inode);
+	sb->s_root = root;
+	if (!root)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&efivarfs_list);
+
+	err = efivar_init(efivarfs_callback, (void *)sb, false,
+			  true, &efivarfs_list);
+	if (err)
+		__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
+
+	return err;
+}
+
+static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
+				    int flags, const char *dev_name, void *data)
+{
+	return mount_single(fs_type, flags, data, efivarfs_fill_super);
+}
+
+static void efivarfs_kill_sb(struct super_block *sb)
+{
+	kill_litter_super(sb);
+	efivarfs_sb = NULL;
+
+	/* Remove all entries and destroy */
+	__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
+}
+
+static struct file_system_type efivarfs_type = {
+	.name    = "efivarfs",
+	.mount   = efivarfs_mount,
+	.kill_sb = efivarfs_kill_sb,
+};
+
+static __init int efivarfs_init(void)
+{
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return 0;
+
+	if (!efivars_kobject())
+		return 0;
+
+	return register_filesystem(&efivarfs_type);
+}
+
+MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
+MODULE_DESCRIPTION("EFI Variable Filesystem");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_FS("efivarfs");
+
+module_init(efivarfs_init);