5 files changed, 514 insertions, 273 deletions

diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index d57ee15874f9..cb1b6d0c3454 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -36,28 +36,41 @@ static ssize_t efivarfs_file_write(struct file *file,
 	if (IS_ERR(data))
 		return PTR_ERR(data);
 
+	inode_lock(inode);
+	if (var->removed) {
+		/*
+		 * file got removed; don't allow a set.  Caused by an
+		 * unsuccessful create or successful delete write
+		 * racing with us.
+		 */
+		bytes = -EIO;
+		goto out;
+	}
+
 	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
 					  data, &set);
-	if (!set && bytes) {
+	if (!set) {
 		if (bytes == -ENOENT)
 			bytes = -EIO;
 		goto out;
 	}
 
 	if (bytes == -ENOENT) {
-		drop_nlink(inode);
-		d_delete(file->f_path.dentry);
-		dput(file->f_path.dentry);
+		/*
+		 * zero size signals to release that the write deleted
+		 * the variable
+		 */
+		i_size_write(inode, 0);
 	} else {
-		inode_lock(inode);
 		i_size_write(inode, datasize + sizeof(attributes));
-		inode->i_mtime = current_time(inode);
-		inode_unlock(inode);
+		inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
 	}
 
 	bytes = count;
 
 out:
+	inode_unlock(inode);
+
 	kfree(data);
 
 	return bytes;
@@ -106,9 +119,36 @@ out_free:
 	return size;
 }
 
+static int efivarfs_file_release(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *var = inode->i_private;
+
+	inode_lock(inode);
+	var->removed = (--var->open_count == 0 && i_size_read(inode) == 0);
+	inode_unlock(inode);
+
+	if (var->removed)
+		simple_recursive_removal(file->f_path.dentry, NULL);
+
+	return 0;
+}
+
+static int efivarfs_file_open(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *entry = inode->i_private;
+
+	file->private_data = entry;
+
+	inode_lock(inode);
+	entry->open_count++;
+	inode_unlock(inode);
+
+	return 0;
+}
+
 const struct file_operations efivarfs_file_operations = {
-	.open	= simple_open,
-	.read	= efivarfs_file_read,
-	.write	= efivarfs_file_write,
-	.llseek	= no_llseek,
+	.open		= efivarfs_file_open,
+	.read		= efivarfs_file_read,
+	.write		= efivarfs_file_write,
+	.release	= efivarfs_file_release,
 };
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 617f3ad2485e..95dcad83da11 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -21,11 +21,15 @@ struct inode *efivarfs_get_inode(struct super_block *sb,
 				dev_t dev, bool is_removable)
 {
 	struct inode *inode = new_inode(sb);
+	struct efivarfs_fs_info *fsi = sb->s_fs_info;
+	struct efivarfs_mount_opts *opts = &fsi->mount_opts;
 
 	if (inode) {
+		inode->i_uid = opts->uid;
+		inode->i_gid = opts->gid;
 		inode->i_ino = get_next_ino();
 		inode->i_mode = mode;
-		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+		simple_inode_init_ts(inode);
 		inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
 		switch (mode & S_IFMT) {
 		case S_IFREG:
@@ -47,7 +51,7 @@ struct inode *efivarfs_get_inode(struct super_block *sb,
  *
  *	VariableName-12345678-1234-1234-1234-1234567891bc
  */
-bool efivarfs_valid_name(const char *str, int len)
+static bool efivarfs_valid_name(const char *str, int len)
 {
 	const char *s = str + len - EFI_VARIABLE_GUID_LEN;
 
@@ -70,41 +74,37 @@ bool efivarfs_valid_name(const char *str, int len)
 	return uuid_is_valid(s);
 }
 
-static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			   struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode = NULL;
 	struct efivar_entry *var;
 	int namelen, i = 0, err = 0;
 	bool is_removable = false;
+	efi_guid_t vendor;
 
 	if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
 		return -EINVAL;
 
-	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
-	if (!var)
-		return -ENOMEM;
-
 	/* length of the variable name itself: remove GUID and separator */
 	namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
 
-	err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid);
+	err = guid_parse(dentry->d_name.name + namelen + 1, &vendor);
 	if (err)
-		goto out;
-	if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) {
-		err = -EPERM;
-		goto out;
-	}
+		return err;
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return -EPERM;
 
-	if (efivar_variable_is_removable(var->var.VendorGuid,
+	if (efivar_variable_is_removable(vendor,
 					 dentry->d_name.name, namelen))
 		is_removable = true;
 
 	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
-	if (!inode) {
-		err = -ENOMEM;
-		goto out;
-	}
+	if (!inode)
+		return -ENOMEM;
+	var = efivar_entry(inode);
+
+	var->var.VendorGuid = vendor;
 
 	for (i = 0; i < namelen; i++)
 		var->var.VariableName[i] = dentry->d_name.name[i];
@@ -112,21 +112,10 @@ static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir,
 	var->var.VariableName[i] = '\0';
 
 	inode->i_private = var;
-	kmemleak_ignore(var);
 
-	err = efivar_entry_add(var, &efivarfs_list);
-	if (err)
-		goto out;
-
-	d_instantiate(dentry, inode);
-	dget(dentry);
-out:
-	if (err) {
-		kfree(var);
-		if (inode)
-			iput(inode);
-	}
-	return err;
+	d_make_persistent(dentry, inode);
+
+	return 0;
 }
 
 static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
@@ -136,9 +125,7 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
 	if (efivar_entry_delete(var))
 		return -EINVAL;
 
-	drop_nlink(d_inode(dentry));
-	dput(dentry);
-	return 0;
+	return simple_unlink(dir, dentry);
 };
 
 const struct inode_operations efivarfs_dir_inode_operations = {
@@ -148,7 +135,7 @@ const struct inode_operations efivarfs_dir_inode_operations = {
 };
 
 static int
-efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+efivarfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 {
 	unsigned int i_flags;
 	unsigned int flags = 0;
@@ -163,8 +150,8 @@ efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 }
 
 static int
-efivarfs_fileattr_set(struct user_namespace *mnt_userns,
-		      struct dentry *dentry, struct fileattr *fa)
+efivarfs_fileattr_set(struct mnt_idmap *idmap,
+		      struct dentry *dentry, struct file_kattr *fa)
 {
 	unsigned int i_flags = 0;
 
@@ -182,7 +169,24 @@ efivarfs_fileattr_set(struct user_namespace *mnt_userns,
 	return 0;
 }
 
+/* copy of simple_setattr except that it doesn't do i_size updates */
+static int efivarfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		   struct iattr *iattr)
+{
+	struct inode *inode = d_inode(dentry);
+	int error;
+
+	error = setattr_prepare(idmap, dentry, iattr);
+	if (error)
+		return error;
+
+	setattr_copy(idmap, inode, iattr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
 static const struct inode_operations efivarfs_file_inode_operations = {
 	.fileattr_get = efivarfs_fileattr_get,
 	.fileattr_set = efivarfs_fileattr_set,
+	.setattr      = efivarfs_setattr,
 };
diff --git a/fs/efivarfs/internal.h b/fs/efivarfs/internal.h
index 8ebf3a6a8aa2..f913b6824289 100644
--- a/fs/efivarfs/internal.h
+++ b/fs/efivarfs/internal.h
@@ -6,30 +6,39 @@
 #ifndef EFIVAR_FS_INTERNAL_H
 #define EFIVAR_FS_INTERNAL_H
 
-#include <linux/list.h>
 #include <linux/efi.h>
 
+struct efivarfs_mount_opts {
+	kuid_t uid;
+	kgid_t gid;
+};
+
+struct efivarfs_fs_info {
+	struct efivarfs_mount_opts mount_opts;
+	struct super_block *sb;
+	struct notifier_block nb;
+};
+
 struct efi_variable {
 	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
 	efi_guid_t    VendorGuid;
-	unsigned long DataSize;
-	__u8          Data[1024];
-	efi_status_t  Status;
-	__u32         Attributes;
-} __attribute__((packed));
+};
 
 struct efivar_entry {
 	struct efi_variable var;
-	struct list_head list;
-	struct kobject kobj;
+	struct inode vfs_inode;
+	unsigned long open_count;
+	bool removed;
 };
 
+static inline struct efivar_entry *efivar_entry(struct inode *inode)
+{
+	return container_of(inode, struct efivar_entry, vfs_inode);
+}
+
 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
-		void *data, bool duplicates, struct list_head *head);
+		void *data, bool duplicate_check);
 
-int efivar_entry_add(struct efivar_entry *entry, struct list_head *head);
-void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head);
-void efivar_entry_remove(struct efivar_entry *entry);
 int efivar_entry_delete(struct efivar_entry *entry);
 
 int efivar_entry_size(struct efivar_entry *entry, unsigned long *size);
@@ -40,21 +49,19 @@ int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
 			      unsigned long *size, void *data, bool *set);
 
-int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
-		      struct list_head *head, void *data);
 
 bool efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
 		     unsigned long data_size);
 bool efivar_variable_is_removable(efi_guid_t vendor, const char *name,
 				  size_t len);
+char *efivar_get_utf8name(const efi_char16_t *name16, efi_guid_t *vendor);
+bool efivarfs_variable_is_present(efi_char16_t *variable_name,
+				  efi_guid_t *vendor, void *data);
 
 extern const struct file_operations efivarfs_file_operations;
 extern const struct inode_operations efivarfs_dir_inode_operations;
-extern bool efivarfs_valid_name(const char *str, int len);
 extern struct inode *efivarfs_get_inode(struct super_block *sb,
 			const struct inode *dir, int mode, dev_t dev,
 			bool is_removable);
 
-extern struct list_head efivarfs_list;
-
 #endif /* EFIVAR_FS_INTERNAL_H */
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 07e82e246666..9da992925920 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -8,25 +8,131 @@
 #include <linux/efi.h>
 #include <linux/fs.h>
 #include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/module.h>
 #include <linux/pagemap.h>
 #include <linux/ucs2_string.h>
 #include <linux/slab.h>
+#include <linux/suspend.h>
 #include <linux/magic.h>
+#include <linux/statfs.h>
+#include <linux/notifier.h>
+#include <linux/printk.h>
+#include <linux/namei.h>
 
 #include "internal.h"
+#include "../internal.h"
 
-LIST_HEAD(efivarfs_list);
+static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event,
+				 void *data)
+{
+	struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb);
+
+	switch (event) {
+	case EFIVAR_OPS_RDONLY:
+		sfi->sb->s_flags |= SB_RDONLY;
+		break;
+	case EFIVAR_OPS_RDWR:
+		sfi->sb->s_flags &= ~SB_RDONLY;
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct inode *efivarfs_alloc_inode(struct super_block *sb)
+{
+	struct efivar_entry *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+
+	if (!entry)
+		return NULL;
+
+	inode_init_once(&entry->vfs_inode);
+	entry->removed = false;
 
-static void efivarfs_evict_inode(struct inode *inode)
+	return &entry->vfs_inode;
+}
+
+static void efivarfs_free_inode(struct inode *inode)
 {
-	clear_inode(inode);
+	struct efivar_entry *entry = efivar_entry(inode);
+
+	kfree(entry);
 }
 
+static int efivarfs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct super_block *sb = root->d_sb;
+	struct efivarfs_fs_info *sbi = sb->s_fs_info;
+	struct efivarfs_mount_opts *opts = &sbi->mount_opts;
+
+	if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+		seq_printf(m, ",uid=%u",
+				from_kuid_munged(&init_user_ns, opts->uid));
+	if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+		seq_printf(m, ",gid=%u",
+				from_kgid_munged(&init_user_ns, opts->gid));
+	return 0;
+}
+
+static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	const u32 attr = EFI_VARIABLE_NON_VOLATILE |
+			 EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			 EFI_VARIABLE_RUNTIME_ACCESS;
+	u64 storage_space, remaining_space, max_variable_size;
+	u64 id = huge_encode_dev(dentry->d_sb->s_dev);
+	efi_status_t status;
+
+	/* Some UEFI firmware does not implement QueryVariableInfo() */
+	storage_space = remaining_space = 0;
+	if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {
+		status = efivar_query_variable_info(attr, &storage_space,
+						    &remaining_space,
+						    &max_variable_size);
+		if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
+			pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",
+					    status);
+	}
+
+	/*
+	 * This is not a normal filesystem, so no point in pretending it has a block
+	 * size; we declare f_bsize to 1, so that we can then report the exact value
+	 * sent by EFI QueryVariableInfo in f_blocks and f_bfree
+	 */
+	buf->f_bsize	= 1;
+	buf->f_namelen	= NAME_MAX;
+	buf->f_blocks	= storage_space;
+	buf->f_bfree	= remaining_space;
+	buf->f_type	= dentry->d_sb->s_magic;
+	buf->f_fsid	= u64_to_fsid(id);
+
+	/*
+	 * In f_bavail we declare the free space that the kernel will allow writing
+	 * when the storage_paranoia x86 quirk is active. To use more, users
+	 * should boot the kernel with efi_no_storage_paranoia.
+	 */
+	if (remaining_space > efivar_reserved_space())
+		buf->f_bavail = remaining_space - efivar_reserved_space();
+	else
+		buf->f_bavail = 0;
+
+	return 0;
+}
+
+static int efivarfs_freeze_fs(struct super_block *sb);
+static int efivarfs_unfreeze_fs(struct super_block *sb);
+
 static const struct super_operations efivarfs_ops = {
-	.statfs = simple_statfs,
-	.drop_inode = generic_delete_inode,
-	.evict_inode = efivarfs_evict_inode,
+	.statfs = efivarfs_statfs,
+	.drop_inode = inode_just_drop,
+	.alloc_inode = efivarfs_alloc_inode,
+	.free_inode = efivarfs_free_inode,
+	.show_options = efivarfs_show_options,
+	.freeze_fs = efivarfs_freeze_fs,
+	.unfreeze_fs = efivarfs_unfreeze_fs,
 };
 
 /*
@@ -46,6 +152,10 @@ static int efivarfs_d_compare(const struct dentry *dentry,
 {
 	int guid = len - EFI_VARIABLE_GUID_LEN;
 
+	/* Parallel lookups may produce a temporary invalid filename */
+	if (guid <= 0)
+		return 1;
+
 	if (name->len != len)
 		return 1;
 
@@ -63,9 +173,6 @@ static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 	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);
 
@@ -80,7 +187,6 @@ static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 static const struct dentry_operations efivarfs_d_ops = {
 	.d_compare = efivarfs_d_compare,
 	.d_hash = efivarfs_d_hash,
-	.d_delete = always_delete_dentry,
 };
 
 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
@@ -103,55 +209,60 @@ static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 	return ERR_PTR(-ENOMEM);
 }
 
-static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
-			     unsigned long name_size, void *data)
+bool efivarfs_variable_is_present(efi_char16_t *variable_name,
+				  efi_guid_t *vendor, void *data)
+{
+	char *name = efivar_get_utf8name(variable_name, vendor);
+	struct super_block *sb = data;
+	struct dentry *dentry;
+
+	if (!name)
+		/*
+		 * If the allocation failed there'll already be an
+		 * error in the log (and likely a huge and growing
+		 * number of them since they system will be under
+		 * extreme memory pressure), so simply assume
+		 * collision for safety but don't add to the log
+		 * flood.
+		 */
+		return true;
+
+	dentry = try_lookup_noperm(&QSTR(name), sb->s_root);
+	kfree(name);
+	if (!IS_ERR_OR_NULL(dentry))
+		dput(dentry);
+
+	return dentry != NULL;
+}
+
+static int efivarfs_create_dentry(struct super_block *sb, efi_char16_t *name16,
+				  unsigned long name_size, efi_guid_t vendor,
+				  char *name)
 {
-	struct super_block *sb = (struct super_block *)data;
 	struct efivar_entry *entry;
-	struct inode *inode = NULL;
+	struct inode *inode;
 	struct dentry *dentry, *root = sb->s_root;
 	unsigned long size = 0;
-	char *name;
 	int len;
 	int err = -ENOMEM;
 	bool is_removable = false;
 
-	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
-		return 0;
-
-	entry = kzalloc(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 = ucs2_utf8size(entry->var.VariableName);
-
-	/* name, plus '-', plus GUID, plus NUL*/
-	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
-	if (!name)
-		goto fail;
-
-	ucs2_as_utf8(name, entry->var.VariableName, len);
+	/* length of the variable name itself: remove GUID and separator */
+	len = strlen(name) - EFI_VARIABLE_GUID_LEN - 1;
 
-	if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
+	if (efivar_variable_is_removable(vendor, name, len))
 		is_removable = true;
 
-	name[len] = '-';
-
-	efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
-
-	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
-
-	/* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
-	strreplace(name, '/', '!');
-
 	inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
 				   is_removable);
 	if (!inode)
 		goto fail_name;
 
+	entry = efivar_entry(inode);
+
+	memcpy(entry->var.VariableName, name16, name_size);
+	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
+
 	dentry = efivarfs_alloc_dentry(root, name);
 	if (IS_ERR(dentry)) {
 		err = PTR_ERR(dentry);
@@ -159,16 +270,16 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
 	}
 
 	__efivar_entry_get(entry, NULL, &size, NULL);
-	__efivar_entry_add(entry, &efivarfs_list);
 
 	/* copied by the above to local storage in the dentry. */
 	kfree(name);
 
 	inode_lock(inode);
 	inode->i_private = entry;
-	i_size_write(inode, size + sizeof(entry->var.Attributes));
+	i_size_write(inode, size + sizeof(__u32)); /* attributes + data */
 	inode_unlock(inode);
-	d_add(dentry, inode);
+	d_make_persistent(dentry, inode);
+	dput(dentry);
 
 	return 0;
 
@@ -176,20 +287,64 @@ fail_inode:
 	iput(inode);
 fail_name:
 	kfree(name);
-fail:
-	kfree(entry);
+
 	return err;
 }
 
-static int efivarfs_destroy(struct efivar_entry *entry, void *data)
+static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
+			     unsigned long name_size, void *data)
 {
-	efivar_entry_remove(entry);
-	kfree(entry);
+	struct super_block *sb = (struct super_block *)data;
+	char *name;
+
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return 0;
+
+	name = efivar_get_utf8name(name16, &vendor);
+	if (!name)
+		return -ENOMEM;
+
+	return efivarfs_create_dentry(sb, name16, name_size, vendor, name);
+}
+
+enum {
+	Opt_uid, Opt_gid,
+};
+
+static const struct fs_parameter_spec efivarfs_parameters[] = {
+	fsparam_uid("uid", Opt_uid),
+	fsparam_gid("gid", Opt_gid),
+	{},
+};
+
+static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct efivarfs_fs_info *sbi = fc->s_fs_info;
+	struct efivarfs_mount_opts *opts = &sbi->mount_opts;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, efivarfs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_uid:
+		opts->uid = result.uid;
+		break;
+	case Opt_gid:
+		opts->gid = result.gid;
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
 static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
+	struct efivarfs_fs_info *sfi = sb->s_fs_info;
 	struct inode *inode = NULL;
 	struct dentry *root;
 	int err;
@@ -199,7 +354,8 @@ static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_blocksize_bits    = PAGE_SHIFT;
 	sb->s_magic             = EFIVARFS_MAGIC;
 	sb->s_op                = &efivarfs_ops;
-	sb->s_d_op		= &efivarfs_d_ops;
+	set_default_d_op(sb, &efivarfs_d_ops);
+	sb->s_d_flags |= DCACHE_DONTCACHE;
 	sb->s_time_gran         = 1;
 
 	if (!efivar_supports_writes())
@@ -215,13 +371,13 @@ static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (!root)
 		return -ENOMEM;
 
-	INIT_LIST_HEAD(&efivarfs_list);
-
-	err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
+	sfi->sb = sb;
+	sfi->nb.notifier_call = efivarfs_ops_notifier;
+	err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);
 	if (err)
-		efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL);
+		return err;
 
-	return err;
+	return efivar_init(efivarfs_callback, sb, true);
 }
 
 static int efivarfs_get_tree(struct fs_context *fc)
@@ -229,22 +385,147 @@ static int efivarfs_get_tree(struct fs_context *fc)
 	return get_tree_single(fc, efivarfs_fill_super);
 }
 
+static int efivarfs_reconfigure(struct fs_context *fc)
+{
+	if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) {
+		pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void efivarfs_free(struct fs_context *fc)
+{
+	kfree(fc->s_fs_info);
+}
+
 static const struct fs_context_operations efivarfs_context_ops = {
 	.get_tree	= efivarfs_get_tree,
+	.parse_param	= efivarfs_parse_param,
+	.reconfigure	= efivarfs_reconfigure,
+	.free		= efivarfs_free,
 };
 
+static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
+				  unsigned long name_size, void *data)
+{
+	char *name;
+	struct super_block *sb = data;
+	struct dentry *dentry;
+	int err;
+
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return 0;
+
+	name = efivar_get_utf8name(name16, &vendor);
+	if (!name)
+		return -ENOMEM;
+
+	dentry = try_lookup_noperm(&QSTR(name), sb->s_root);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out;
+	}
+
+	if (!dentry) {
+		/* found missing entry */
+		pr_info("efivarfs: creating variable %s\n", name);
+		return efivarfs_create_dentry(sb, name16, name_size, vendor, name);
+	}
+
+	dput(dentry);
+	err = 0;
+
+ out:
+	kfree(name);
+
+	return err;
+}
+
+static struct file_system_type efivarfs_type;
+
+static int efivarfs_freeze_fs(struct super_block *sb)
+{
+	/* Nothing for us to do. */
+	return 0;
+}
+
+static int efivarfs_unfreeze_fs(struct super_block *sb)
+{
+	struct dentry *child = NULL;
+
+	/*
+	 * Unconditionally resync the variable state on a thaw request.
+	 * Given the size of efivarfs it really doesn't matter to simply
+	 * iterate through all of the entries and resync. Freeze/thaw
+	 * requests are rare enough for that to not matter and the
+	 * number of entries is pretty low too. So we really don't care.
+	 */
+	pr_info("efivarfs: resyncing variable state\n");
+	for (;;) {
+		int err;
+		unsigned long size = 0;
+		struct inode *inode;
+		struct efivar_entry *entry;
+
+		child = find_next_child(sb->s_root, child);
+		if (!child)
+			break;
+
+		inode = d_inode(child);
+		entry = efivar_entry(inode);
+
+		err = efivar_entry_size(entry, &size);
+		if (err)
+			size = 0;
+		else
+			size += sizeof(__u32);
+
+		inode_lock(inode);
+		i_size_write(inode, size);
+		inode_unlock(inode);
+
+		/* The variable doesn't exist anymore, delete it. */
+		if (!size) {
+			pr_info("efivarfs: removing variable %pd\n", child);
+			simple_recursive_removal(child, NULL);
+		}
+	}
+
+	efivar_init(efivarfs_check_missing, sb, false);
+	pr_info("efivarfs: finished resyncing variable state\n");
+	return 0;
+}
+
 static int efivarfs_init_fs_context(struct fs_context *fc)
 {
+	struct efivarfs_fs_info *sfi;
+
+	if (!efivar_is_available())
+		return -EOPNOTSUPP;
+
+	sfi = kzalloc(sizeof(*sfi), GFP_KERNEL);
+	if (!sfi)
+		return -ENOMEM;
+
+	sfi->mount_opts.uid = GLOBAL_ROOT_UID;
+	sfi->mount_opts.gid = GLOBAL_ROOT_GID;
+
+	fc->s_fs_info = sfi;
 	fc->ops = &efivarfs_context_ops;
+
 	return 0;
 }
 
 static void efivarfs_kill_sb(struct super_block *sb)
 {
-	kill_litter_super(sb);
+	struct efivarfs_fs_info *sfi = sb->s_fs_info;
 
-	/* Remove all entries and destroy */
-	efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL);
+	blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
+	kill_anon_super(sb);
+
+	kfree(sfi);
 }
 
 static struct file_system_type efivarfs_type = {
@@ -252,13 +533,12 @@ static struct file_system_type efivarfs_type = {
 	.name    = "efivarfs",
 	.init_fs_context = efivarfs_init_fs_context,
 	.kill_sb = efivarfs_kill_sb,
+	.parameters = efivarfs_parameters,
+	.fs_flags = FS_POWER_FREEZE,
 };
 
 static __init int efivarfs_init(void)
 {
-	if (!efivars_kobject())
-		return -ENODEV;
-
 	return register_filesystem(&efivarfs_type);
 }
 
diff --git a/fs/efivarfs/vars.c b/fs/efivarfs/vars.c
index 9e4f47808bd5..6edc10958ecf 100644
--- a/fs/efivarfs/vars.c
+++ b/fs/efivarfs/vars.c
@@ -22,7 +22,7 @@
 
 #include "internal.h"
 
-MODULE_IMPORT_NS(EFIVAR);
+MODULE_IMPORT_NS("EFIVAR");
 
 static bool
 validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
@@ -225,6 +225,31 @@ variable_matches(const char *var_name, size_t len, const char *match_name,
 	}
 }
 
+char *
+efivar_get_utf8name(const efi_char16_t *name16, efi_guid_t *vendor)
+{
+	int len = ucs2_utf8size(name16);
+	char *name;
+
+	/* name, plus '-', plus GUID, plus NUL*/
+	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
+	if (!name)
+		return NULL;
+
+	ucs2_as_utf8(name, name16, len);
+
+	name[len] = '-';
+
+	efi_guid_to_str(vendor, name + len + 1);
+
+	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
+
+	/* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
+	strreplace(name, '/', '!');
+
+	return name;
+}
+
 bool
 efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
 		unsigned long data_size)
@@ -288,28 +313,6 @@ efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
 	return found;
 }
 
-static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
-				struct list_head *head)
-{
-	struct efivar_entry *entry, *n;
-	unsigned long strsize1, strsize2;
-	bool found = false;
-
-	strsize1 = ucs2_strsize(variable_name, 1024);
-	list_for_each_entry_safe(entry, n, head, list) {
-		strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
-		if (strsize1 == strsize2 &&
-			!memcmp(variable_name, &(entry->var.VariableName),
-				strsize2) &&
-			!efi_guidcmp(entry->var.VendorGuid,
-				*vendor)) {
-			found = true;
-			break;
-		}
-	}
-	return found;
-}
-
 /*
  * Returns the size of variable_name, in bytes, including the
  * terminating NULL character, or variable_name_size if no NULL
@@ -361,18 +364,17 @@ static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
  * efivar_init - build the initial list of EFI variables
  * @func: callback function to invoke for every variable
  * @data: function-specific data to pass to @func
- * @duplicates: error if we encounter duplicates on @head?
- * @head: initialised head of variable list
+ * @duplicate_check: fail if a duplicate variable is found
  *
  * Get every EFI variable from the firmware and invoke @func. @func
- * should call efivar_entry_add() to build the list of variables.
+ * should populate the initial dentry and inode tree.
  *
  * Returns 0 on success, or a kernel error code on failure.
  */
 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
-		void *data, bool duplicates, struct list_head *head)
+		void *data, bool duplicate_check)
 {
-	unsigned long variable_name_size = 1024;
+	unsigned long variable_name_size = 512;
 	efi_char16_t *variable_name;
 	efi_status_t status;
 	efi_guid_t vendor_guid;
@@ -389,12 +391,14 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
 		goto free;
 
 	/*
-	 * Per EFI spec, the maximum storage allocated for both
-	 * the variable name and variable data is 1024 bytes.
+	 * A small set of old UEFI implementations reject sizes
+	 * above a certain threshold, the lowest seen in the wild
+	 * is 512.
 	 */
 
 	do {
-		variable_name_size = 1024;
+		variable_name_size = 512;
+		BUILD_BUG_ON(EFI_VAR_NAME_LEN < 512);
 
 		status = efivar_get_next_variable(&variable_name_size,
 						  variable_name,
@@ -412,9 +416,9 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
 			 * we'll ever see a different variable name,
 			 * and may end up looping here forever.
 			 */
-			if (duplicates &&
-			    variable_is_present(variable_name, &vendor_guid,
-						head)) {
+			if (duplicate_check &&
+			    efivarfs_variable_is_present(variable_name,
+							 &vendor_guid, data)) {
 				dup_variable_bug(variable_name, &vendor_guid,
 						 variable_name_size);
 				status = EFI_NOT_FOUND;
@@ -431,9 +435,13 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
 			break;
 		case EFI_NOT_FOUND:
 			break;
+		case EFI_BUFFER_TOO_SMALL:
+			pr_warn("efivars: Variable name size exceeds maximum (%lu > 512)\n",
+				variable_name_size);
+			status = EFI_NOT_FOUND;
+			break;
 		default:
-			printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
-				status);
+			pr_warn("efivars: get_next_variable: status=%lx\n", status);
 			status = EFI_NOT_FOUND;
 			break;
 		}
@@ -448,70 +456,12 @@ free:
 }
 
 /**
- * efivar_entry_add - add entry to variable list
- * @entry: entry to add to list
- * @head: list head
- *
- * Returns 0 on success, or a kernel error code on failure.
- */
-int efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
-{
-	int err;
-
-	err = efivar_lock();
-	if (err)
-		return err;
-	list_add(&entry->list, head);
-	efivar_unlock();
-
-	return 0;
-}
-
-/**
- * __efivar_entry_add - add entry to variable list
- * @entry: entry to add to list
- * @head: list head
- */
-void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
-{
-	list_add(&entry->list, head);
-}
-
-/**
- * efivar_entry_remove - remove entry from variable list
- * @entry: entry to remove from list
- *
- * Returns 0 on success, or a kernel error code on failure.
- */
-void efivar_entry_remove(struct efivar_entry *entry)
-{
-	list_del(&entry->list);
-}
-
-/*
- * efivar_entry_list_del_unlock - remove entry from variable list
- * @entry: entry to remove
- *
- * Remove @entry from the variable list and release the list lock.
- *
- * NOTE: slightly weird locking semantics here - we expect to be
- * called with the efivars lock already held, and we release it before
- * returning. This is because this function is usually called after
- * set_variable() while the lock is still held.
- */
-static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
-{
-	list_del(&entry->list);
-	efivar_unlock();
-}
-
-/**
- * efivar_entry_delete - delete variable and remove entry from list
+ * efivar_entry_delete - delete variable
  * @entry: entry containing variable to delete
  *
- * Delete the variable from the firmware and remove @entry from the
- * variable list. It is the caller's responsibility to free @entry
- * once we return.
+ * Delete the variable from the firmware. It is the caller's
+ * responsibility to free @entry (by deleting the dentry/inode) once
+ * we return.
  *
  * Returns 0 on success, -EINTR if we can't grab the semaphore,
  * converted EFI status code if set_variable() fails.
@@ -528,12 +478,10 @@ int efivar_entry_delete(struct efivar_entry *entry)
 	status = efivar_set_variable_locked(entry->var.VariableName,
 					    &entry->var.VendorGuid,
 					    0, 0, NULL, false);
-	if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
-		efivar_unlock();
+	efivar_unlock();
+	if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND))
 		return efi_status_to_err(status);
-	}
 
-	efivar_entry_list_del_unlock(entry);
 	return 0;
 }
 
@@ -627,7 +575,7 @@ int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
  * get_variable() fail.
  *
  * If the EFI variable does not exist when calling set_variable()
- * (EFI_NOT_FOUND), @entry is removed from the variable list.
+ * (EFI_NOT_FOUND).
  */
 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
 			      unsigned long *size, void *data, bool *set)
@@ -643,9 +591,8 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
 		return -EINVAL;
 
 	/*
-	 * The lock here protects the get_variable call, the conditional
-	 * set_variable call, and removal of the variable from the efivars
-	 * list (in the case of an authenticated delete).
+	 * The lock here protects the get_variable call and the
+	 * conditional set_variable call
 	 */
 	err = efivar_lock();
 	if (err)
@@ -671,10 +618,7 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
 				    &entry->var.VendorGuid,
 				    NULL, size, NULL);
 
-	if (status == EFI_NOT_FOUND)
-		efivar_entry_list_del_unlock(entry);
-	else
-		efivar_unlock();
+	efivar_unlock();
 
 	if (status && status != EFI_BUFFER_TOO_SMALL)
 		return efi_status_to_err(status);
@@ -686,37 +630,3 @@ out:
 	return err;
 
 }
-
-/**
- * efivar_entry_iter - iterate over variable list
- * @func: callback function
- * @head: head of variable list
- * @data: function-specific data to pass to callback
- *
- * Iterate over the list of EFI variables and call @func with every
- * entry on the list. It is safe for @func to remove entries in the
- * list via efivar_entry_delete() while iterating.
- *
- * Some notes for the callback function:
- *  - a non-zero return value indicates an error and terminates the loop
- *  - @func is called from atomic context
- */
-int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
-		      struct list_head *head, void *data)
-{
-	struct efivar_entry *entry, *n;
-	int err = 0;
-
-	err = efivar_lock();
-	if (err)
-		return err;
-
-	list_for_each_entry_safe(entry, n, head, list) {
-		err = func(entry, data);
-		if (err)
-			break;
-	}
-	efivar_unlock();
-
-	return err;
-}