[RFC,3/3] efivarfs: replace iterate_dir with libfs function simple_iterate_call

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 81b3c6b7e100..135b0bb9b4b5 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -393,29 +393,13 @@  static const struct fs_context_operations efivarfs_context_ops = {
 	.reconfigure	= efivarfs_reconfigure,
 };
 
-struct efivarfs_ctx {
-	struct dir_context ctx;
-	struct super_block *sb;
-	struct dentry *dentry;
-};
-
-static bool efivarfs_actor(struct dir_context *ctx, const char *name, int len,
-			   loff_t offset, u64 ino, unsigned mode)
+static bool efivarfs_iterate_callback(void *data, struct dentry *dentry)
 {
 	unsigned long size;
-	struct efivarfs_ctx *ectx = container_of(ctx, struct efivarfs_ctx, ctx);
-	struct qstr qstr = { .name = name, .len = len };
-	struct dentry *dentry = d_hash_and_lookup(ectx->sb->s_root, &qstr);
-	struct inode *inode;
-	struct efivar_entry *entry;
+	struct inode *inode = d_inode(dentry);
+	struct efivar_entry *entry = efivar_entry(inode);
 	int err;
 
-	if (IS_ERR_OR_NULL(dentry))
-		return true;
-
-	inode = d_inode(dentry);
-	entry = efivar_entry(inode);
-
 	err = efivar_entry_size(entry, &size);
 	size += sizeof(__u32);	/* attributes */
 	if (err)
@@ -426,12 +410,10 @@  static bool efivarfs_actor(struct dir_context *ctx, const char *name, int len,
 	inode_unlock(inode);
 
 	if (!size) {
-		ectx->dentry = dentry;
-		return false;
+		pr_info("efivarfs: removing variable %pd\n", dentry);
+		simple_recursive_removal(dentry, NULL);
 	}
 
-	dput(dentry);
-
 	return true;
 }
 
@@ -474,33 +456,11 @@  static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
 	return err;
 }
 
-static void efivarfs_deactivate_super_work(struct work_struct *work)
-{
-	struct super_block *s = container_of(work, struct super_block,
-					     destroy_work);
-	/*
-	 * note: here s->destroy_work is free for reuse (which
-	 * will happen in deactivate_super)
-	 */
-	deactivate_super(s);
-}
-
-static struct file_system_type efivarfs_type;
-
 static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action,
 			      void *ptr)
 {
 	struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info,
 						    pm_nb);
-	struct path path;
-	struct efivarfs_ctx ectx = {
-		.ctx = {
-			.actor	= efivarfs_actor,
-		},
-		.sb = sfi->sb,
-	};
-	struct file *file;
-	struct super_block *s = sfi->sb;
 	static bool rescan_done = true;
 
 	if (action == PM_HIBERNATION_PREPARE) {
@@ -513,64 +473,15 @@  static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action,
 	if (rescan_done)
 		return NOTIFY_DONE;
 
-	/* ensure single superblock is alive and pin it */
-	if (!atomic_inc_not_zero(&s->s_active))
-		return NOTIFY_DONE;
-
 	pr_info("efivarfs: resyncing variable state\n");
 
-	path.dentry = sfi->sb->s_root;
-
-	/*
-	 * do not add SB_KERNMOUNT which a single superblock could
-	 * expose to userspace and which also causes MNT_INTERNAL, see
-	 * below
-	 */
-	path.mnt = vfs_kern_mount(&efivarfs_type, 0,
-				  efivarfs_type.name, NULL);
-	if (IS_ERR(path.mnt)) {
-		pr_err("efivarfs: internal mount failed\n");
-		/*
-		 * We may be the last pinner of the superblock but
-		 * calling efivarfs_kill_sb from within the notifier
-		 * here would deadlock trying to unregister it
-		 */
-		INIT_WORK(&s->destroy_work, efivarfs_deactivate_super_work);
-		schedule_work(&s->destroy_work);
-		return PTR_ERR(path.mnt);
-	}
-
-	/* path.mnt now has pin on superblock, so this must be above one */
-	atomic_dec(&s->s_active);
-
-	file = kernel_file_open(&path, O_RDONLY | O_DIRECTORY | O_NOATIME,
-				current_cred());
-	/*
-	 * safe even if last put because no MNT_INTERNAL means this
-	 * will do delayed deactivate_super and not deadlock
-	 */
-	mntput(path.mnt);
-	if (IS_ERR(file))
-		return NOTIFY_DONE;
-
 	rescan_done = true;
 
 	/*
 	 * First loop over the directory and verify each entry exists,
 	 * removing it if it doesn't
 	 */
-	file->f_pos = 2;	/* skip . and .. */
-	do {
-		ectx.dentry = NULL;
-		iterate_dir(file, &ectx.ctx);
-		if (ectx.dentry) {
-			pr_info("efivarfs: removing variable %pd\n",
-				ectx.dentry);
-			simple_recursive_removal(ectx.dentry, NULL);
-			dput(ectx.dentry);
-		}
-	} while (ectx.dentry);
-	fput(file);
+	simple_iterate_call(sfi->sb->s_root, NULL, efivarfs_iterate_callback);
 
 	/*
 	 * then loop over variables, creating them if there's no matching
@@ -609,8 +520,8 @@  static void efivarfs_kill_sb(struct super_block *sb)
 	struct efivarfs_fs_info *sfi = sb->s_fs_info;
 
 	blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
-	kill_litter_super(sb);
 	unregister_pm_notifier(&sfi->pm_nb);
+	kill_litter_super(sb);
 
 	kfree(sfi);
 }