diff -drupN a/fs/sdcardfs/main.c b/fs/sdcardfs/main.c
--- a/fs/sdcardfs/main.c	1970-01-01 03:00:00.000000000 +0300
+++ b/fs/sdcardfs/main.c	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,490 @@
+/*
+ * fs/sdcardfs/main.c
+ *
+ * Copyright (c) 2013 Samsung Electronics Co. Ltd
+ *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
+ *               Sunghwan Yun, Sungjong Seo
+ *
+ * This program has been developed as a stackable file system based on
+ * the WrapFS which written by
+ *
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009     Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This file is dual licensed.  It may be redistributed and/or modified
+ * under the terms of the Apache 2.0 License OR version 2 of the GNU
+ * General Public License.
+ */
+
+#include "sdcardfs.h"
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/parser.h>
+
+enum {
+	Opt_fsuid,
+	Opt_fsgid,
+	Opt_gid,
+	Opt_debug,
+	Opt_mask,
+	Opt_multiuser,
+	Opt_userid,
+	Opt_reserved_mb,
+	Opt_gid_derivation,
+	Opt_default_normal,
+	Opt_err,
+};
+
+static const match_table_t sdcardfs_tokens = {
+	{Opt_fsuid, "fsuid=%u"},
+	{Opt_fsgid, "fsgid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_debug, "debug"},
+	{Opt_mask, "mask=%u"},
+	{Opt_userid, "userid=%d"},
+	{Opt_multiuser, "multiuser"},
+	{Opt_gid_derivation, "derive_gid"},
+	{Opt_default_normal, "default_normal"},
+	{Opt_reserved_mb, "reserved_mb=%u"},
+	{Opt_err, NULL}
+};
+
+static int parse_options(struct super_block *sb, char *options, int silent,
+				int *debug, struct sdcardfs_vfsmount_options *vfsopts,
+				struct sdcardfs_mount_options *opts)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+
+	/* by default, we use AID_MEDIA_RW as uid, gid */
+	opts->fs_low_uid = AID_MEDIA_RW;
+	opts->fs_low_gid = AID_MEDIA_RW;
+	vfsopts->mask = 0;
+	opts->multiuser = false;
+	opts->fs_user_id = 0;
+	vfsopts->gid = 0;
+	/* by default, 0MB is reserved */
+	opts->reserved_mb = 0;
+	/* by default, gid derivation is off */
+	opts->gid_derivation = false;
+	opts->default_normal = false;
+
+	*debug = 0;
+
+	if (!options)
+		return 0;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, sdcardfs_tokens, args);
+
+		switch (token) {
+		case Opt_debug:
+			*debug = 1;
+			break;
+		case Opt_fsuid:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->fs_low_uid = option;
+			break;
+		case Opt_fsgid:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->fs_low_gid = option;
+			break;
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			vfsopts->gid = option;
+			break;
+		case Opt_userid:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->fs_user_id = option;
+			break;
+		case Opt_mask:
+			if (match_int(&args[0], &option))
+				return 0;
+			vfsopts->mask = option;
+			break;
+		case Opt_multiuser:
+			opts->multiuser = true;
+			break;
+		case Opt_reserved_mb:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->reserved_mb = option;
+			break;
+		case Opt_gid_derivation:
+			opts->gid_derivation = true;
+			break;
+		case Opt_default_normal:
+			opts->default_normal = true;
+			break;
+		/* unknown option */
+		default:
+			if (!silent)
+				pr_err("Unrecognized mount option \"%s\" or missing value", p);
+			return -EINVAL;
+		}
+	}
+
+	if (*debug) {
+		pr_info("sdcardfs : options - debug:%d\n", *debug);
+		pr_info("sdcardfs : options - uid:%d\n",
+							opts->fs_low_uid);
+		pr_info("sdcardfs : options - gid:%d\n",
+							opts->fs_low_gid);
+	}
+
+	return 0;
+}
+
+int parse_options_remount(struct super_block *sb, char *options, int silent,
+				struct sdcardfs_vfsmount_options *vfsopts)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+	int debug;
+
+	if (!options)
+		return 0;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, sdcardfs_tokens, args);
+
+		switch (token) {
+		case Opt_debug:
+			debug = 1;
+			break;
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			vfsopts->gid = option;
+
+			break;
+		case Opt_mask:
+			if (match_int(&args[0], &option))
+				return 0;
+			vfsopts->mask = option;
+			break;
+		case Opt_default_normal:
+		case Opt_multiuser:
+		case Opt_userid:
+		case Opt_fsuid:
+		case Opt_fsgid:
+		case Opt_reserved_mb:
+			pr_warn("Option \"%s\" can't be changed during remount\n", p);
+			break;
+		/* unknown option */
+		default:
+			if (!silent)
+				pr_err("Unrecognized mount option \"%s\" or missing value", p);
+			return -EINVAL;
+		}
+	}
+
+	if (debug) {
+		pr_info("sdcardfs : options - debug:%d\n", debug);
+		pr_info("sdcardfs : options - gid:%d\n", vfsopts->gid);
+		pr_info("sdcardfs : options - mask:%d\n", vfsopts->mask);
+	}
+
+	return 0;
+}
+
+#if 0
+/*
+ * our custom d_alloc_root work-alike
+ *
+ * we can't use d_alloc_root if we want to use our own interpose function
+ * unchanged, so we simply call our own "fake" d_alloc_root
+ */
+static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
+{
+	struct dentry *ret = NULL;
+
+	if (sb) {
+		static const struct qstr name = {
+			.name = "/",
+			.len = 1
+		};
+
+		ret = d_alloc(NULL, &name);
+		if (ret) {
+			d_set_d_op(ret, &sdcardfs_ci_dops);
+			ret->d_sb = sb;
+			ret->d_parent = ret;
+		}
+	}
+	return ret;
+}
+#endif
+
+DEFINE_MUTEX(sdcardfs_super_list_lock);
+EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
+LIST_HEAD(sdcardfs_super_list);
+EXPORT_SYMBOL_GPL(sdcardfs_super_list);
+
+/*
+ * There is no need to lock the sdcardfs_super_info's rwsem as there is no
+ * way anyone can have a reference to the superblock at this point in time.
+ */
+static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
+		const char *dev_name, void *raw_data, int silent)
+{
+	int err = 0;
+	int debug;
+	struct super_block *lower_sb;
+	struct path lower_path;
+	struct sdcardfs_sb_info *sb_info;
+	struct sdcardfs_vfsmount_options *mnt_opt = mnt->data;
+	struct inode *inode;
+
+	pr_info("sdcardfs version 2.0\n");
+
+	if (!dev_name) {
+		pr_err("sdcardfs: read_super: missing dev_name argument\n");
+		err = -EINVAL;
+		goto out;
+	}
+
+	pr_info("sdcardfs: dev_name -> %s\n", dev_name);
+	pr_info("sdcardfs: options -> %s\n", (char *)raw_data);
+	pr_info("sdcardfs: mnt -> %p\n", mnt);
+
+	/* parse lower path */
+	err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
+			&lower_path);
+	if (err) {
+		pr_err("sdcardfs: error accessing lower directory '%s'\n", dev_name);
+		goto out;
+	}
+
+	/* allocate superblock private data */
+	sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
+	if (!SDCARDFS_SB(sb)) {
+		pr_crit("sdcardfs: read_super: out of memory\n");
+		err = -ENOMEM;
+		goto out_free;
+	}
+
+	sb_info = sb->s_fs_info;
+	/* parse options */
+	err = parse_options(sb, raw_data, silent, &debug, mnt_opt, &sb_info->options);
+	if (err) {
+		pr_err("sdcardfs: invalid options\n");
+		goto out_freesbi;
+	}
+
+	/* set the lower superblock field of upper superblock */
+	lower_sb = lower_path.dentry->d_sb;
+	atomic_inc(&lower_sb->s_active);
+	sdcardfs_set_lower_super(sb, lower_sb);
+
+	/* inherit maxbytes from lower file system */
+	sb->s_maxbytes = lower_sb->s_maxbytes;
+
+	/*
+	 * Our c/m/atime granularity is 1 ns because we may stack on file
+	 * systems whose granularity is as good.
+	 */
+	sb->s_time_gran = 1;
+
+	sb->s_magic = SDCARDFS_SUPER_MAGIC;
+	sb->s_op = &sdcardfs_sops;
+
+	/* get a new inode and allocate our root dentry */
+	inode = sdcardfs_iget(sb, d_inode(lower_path.dentry), 0);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		goto out_sput;
+	}
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root) {
+		err = -ENOMEM;
+		goto out_sput;
+	}
+	d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
+
+	/* link the upper and lower dentries */
+	sb->s_root->d_fsdata = NULL;
+	err = new_dentry_private_data(sb->s_root);
+	if (err)
+		goto out_freeroot;
+
+	/* set the lower dentries for s_root */
+	sdcardfs_set_lower_path(sb->s_root, &lower_path);
+
+	/*
+	 * No need to call interpose because we already have a positive
+	 * dentry, which was instantiated by d_make_root.  Just need to
+	 * d_rehash it.
+	 */
+	d_rehash(sb->s_root);
+
+	/* setup permission policy */
+	sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
+	mutex_lock(&sdcardfs_super_list_lock);
+	if (sb_info->options.multiuser) {
+		setup_derived_state(d_inode(sb->s_root), PERM_PRE_ROOT,
+				sb_info->options.fs_user_id, AID_ROOT);
+		snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
+	} else {
+		setup_derived_state(d_inode(sb->s_root), PERM_ROOT,
+				sb_info->options.fs_user_id, AID_ROOT);
+		snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
+	}
+	fixup_tmp_permissions(d_inode(sb->s_root));
+	sb_info->sb = sb;
+	list_add(&sb_info->list, &sdcardfs_super_list);
+	mutex_unlock(&sdcardfs_super_list_lock);
+
+	if (!silent)
+		pr_info("sdcardfs: mounted on top of %s type %s\n",
+				dev_name, lower_sb->s_type->name);
+	goto out; /* all is well */
+
+	/* no longer needed: free_dentry_private_data(sb->s_root); */
+out_freeroot:
+	dput(sb->s_root);
+	sb->s_root = NULL;
+out_sput:
+	/* drop refs we took earlier */
+	atomic_dec(&lower_sb->s_active);
+out_freesbi:
+	kfree(SDCARDFS_SB(sb));
+	sb->s_fs_info = NULL;
+out_free:
+	path_put(&lower_path);
+
+out:
+	return err;
+}
+
+struct sdcardfs_mount_private {
+	struct vfsmount *mnt;
+	const char *dev_name;
+	void *raw_data;
+};
+
+static int __sdcardfs_fill_super(
+	struct super_block *sb,
+	void *_priv, int silent)
+{
+	struct sdcardfs_mount_private *priv = _priv;
+
+	return sdcardfs_read_super(priv->mnt,
+		sb, priv->dev_name, priv->raw_data, silent);
+}
+
+static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
+		struct file_system_type *fs_type, int flags,
+			    const char *dev_name, void *raw_data)
+{
+	struct sdcardfs_mount_private priv = {
+		.mnt = mnt,
+		.dev_name = dev_name,
+		.raw_data = raw_data
+	};
+
+	return mount_nodev(fs_type, flags,
+		&priv, __sdcardfs_fill_super);
+}
+
+static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type,
+		    int flags, const char *dev_name, void *raw_data)
+{
+	WARN(1, "sdcardfs does not support mount. Use mount2.\n");
+	return ERR_PTR(-EINVAL);
+}
+
+void *sdcardfs_alloc_mnt_data(void)
+{
+	return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
+}
+
+void sdcardfs_kill_sb(struct super_block *sb)
+{
+	struct sdcardfs_sb_info *sbi;
+
+	if (sb->s_magic == SDCARDFS_SUPER_MAGIC && sb->s_fs_info) {
+		sbi = SDCARDFS_SB(sb);
+		mutex_lock(&sdcardfs_super_list_lock);
+		list_del(&sbi->list);
+		mutex_unlock(&sdcardfs_super_list_lock);
+	}
+	kill_anon_super(sb);
+}
+
+static struct file_system_type sdcardfs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= SDCARDFS_NAME,
+	.mount		= sdcardfs_mount_wrn,
+	.mount2		= sdcardfs_mount,
+	.alloc_mnt_data = sdcardfs_alloc_mnt_data,
+	.kill_sb	= sdcardfs_kill_sb,
+	.fs_flags	= 0,
+};
+MODULE_ALIAS_FS(SDCARDFS_NAME);
+
+static int __init init_sdcardfs_fs(void)
+{
+	int err;
+
+	pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
+
+	err = sdcardfs_init_inode_cache();
+	if (err)
+		goto out;
+	err = sdcardfs_init_dentry_cache();
+	if (err)
+		goto out;
+	err = packagelist_init();
+	if (err)
+		goto out;
+	err = register_filesystem(&sdcardfs_fs_type);
+out:
+	if (err) {
+		sdcardfs_destroy_inode_cache();
+		sdcardfs_destroy_dentry_cache();
+		packagelist_exit();
+	}
+	return err;
+}
+
+static void __exit exit_sdcardfs_fs(void)
+{
+	sdcardfs_destroy_inode_cache();
+	sdcardfs_destroy_dentry_cache();
+	packagelist_exit();
+	unregister_filesystem(&sdcardfs_fs_type);
+	pr_info("Completed sdcardfs module unload\n");
+}
+
+/* Original wrapfs authors */
+MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University (http://www.fsl.cs.sunysb.edu/)");
+
+/* Original sdcardfs authors */
+MODULE_AUTHOR("Woojoong Lee, Daeho Jeong, Kitae Lee, Yeongjin Gil System Memory Lab., Samsung Electronics");
+
+/* Current maintainer */
+MODULE_AUTHOR("Daniel Rosenberg, Google");
+MODULE_DESCRIPTION("Sdcardfs " SDCARDFS_VERSION);
+MODULE_LICENSE("GPL");
+
+module_init(init_sdcardfs_fs);
+module_exit(exit_sdcardfs_fs);