diff -drupN a/fs/sdcardfs/derived_perm.c b/fs/sdcardfs/derived_perm.c
--- a/fs/sdcardfs/derived_perm.c	1970-01-01 03:00:00.000000000 +0300
+++ b/fs/sdcardfs/derived_perm.c	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,472 @@
+/*
+ * fs/sdcardfs/derived_perm.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"
+
+/* copy derived state from parent inode */
+static void inherit_derived_state(struct inode *parent, struct inode *child)
+{
+	struct sdcardfs_inode_info *pi = SDCARDFS_I(parent);
+	struct sdcardfs_inode_info *ci = SDCARDFS_I(child);
+
+	ci->data->perm = PERM_INHERIT;
+	ci->data->userid = pi->data->userid;
+	ci->data->d_uid = pi->data->d_uid;
+	ci->data->under_android = pi->data->under_android;
+	ci->data->under_cache = pi->data->under_cache;
+	ci->data->under_obb = pi->data->under_obb;
+}
+
+/* helper function for derived state */
+void setup_derived_state(struct inode *inode, perm_t perm, userid_t userid,
+					uid_t uid)
+{
+	struct sdcardfs_inode_info *info = SDCARDFS_I(inode);
+
+	info->data->perm = perm;
+	info->data->userid = userid;
+	info->data->d_uid = uid;
+	info->data->under_android = false;
+	info->data->under_cache = false;
+	info->data->under_obb = false;
+}
+
+/* While renaming, there is a point where we want the path from dentry,
+ * but the name from newdentry
+ */
+void get_derived_permission_new(struct dentry *parent, struct dentry *dentry,
+				const struct qstr *name)
+{
+	struct sdcardfs_inode_info *info = SDCARDFS_I(d_inode(dentry));
+	struct sdcardfs_inode_info *parent_info = SDCARDFS_I(d_inode(parent));
+	struct sdcardfs_inode_data *parent_data = parent_info->data;
+	appid_t appid;
+	unsigned long user_num;
+	int err;
+	struct qstr q_Android = QSTR_LITERAL("Android");
+	struct qstr q_data = QSTR_LITERAL("data");
+	struct qstr q_obb = QSTR_LITERAL("obb");
+	struct qstr q_media = QSTR_LITERAL("media");
+	struct qstr q_cache = QSTR_LITERAL("cache");
+
+	/* By default, each inode inherits from its parent.
+	 * the properties are maintained on its private fields
+	 * because the inode attributes will be modified with that of
+	 * its lower inode.
+	 * These values are used by our custom permission call instead
+	 * of using the inode permissions.
+	 */
+
+	inherit_derived_state(d_inode(parent), d_inode(dentry));
+
+	/* Files don't get special labels */
+	if (!S_ISDIR(d_inode(dentry)->i_mode)) {
+		set_top(info, parent_info);
+		return;
+	}
+	/* Derive custom permissions based on parent and current node */
+	switch (parent_data->perm) {
+	case PERM_INHERIT:
+	case PERM_ANDROID_PACKAGE_CACHE:
+		set_top(info, parent_info);
+		break;
+	case PERM_PRE_ROOT:
+		/* Legacy internal layout places users at top level */
+		info->data->perm = PERM_ROOT;
+		err = kstrtoul(name->name, 10, &user_num);
+		if (err)
+			info->data->userid = 0;
+		else
+			info->data->userid = user_num;
+		break;
+	case PERM_ROOT:
+		/* Assume masked off by default. */
+		if (qstr_case_eq(name, &q_Android)) {
+			/* App-specific directories inside; let anyone traverse */
+			info->data->perm = PERM_ANDROID;
+			info->data->under_android = true;
+		} else {
+			set_top(info, parent_info);
+		}
+		break;
+	case PERM_ANDROID:
+		if (qstr_case_eq(name, &q_data)) {
+			/* App-specific directories inside; let anyone traverse */
+			info->data->perm = PERM_ANDROID_DATA;
+		} else if (qstr_case_eq(name, &q_obb)) {
+			/* App-specific directories inside; let anyone traverse */
+			info->data->perm = PERM_ANDROID_OBB;
+			info->data->under_obb = true;
+			/* Single OBB directory is always shared */
+		} else if (qstr_case_eq(name, &q_media)) {
+			/* App-specific directories inside; let anyone traverse */
+			info->data->perm = PERM_ANDROID_MEDIA;
+		} else {
+			set_top(info, parent_info);
+		}
+		break;
+	case PERM_ANDROID_OBB:
+	case PERM_ANDROID_DATA:
+	case PERM_ANDROID_MEDIA:
+		info->data->perm = PERM_ANDROID_PACKAGE;
+		appid = get_appid(name->name);
+		if (appid != 0 && !is_excluded(name->name, parent_data->userid))
+			info->data->d_uid =
+				multiuser_get_uid(parent_data->userid, appid);
+		break;
+	case PERM_ANDROID_PACKAGE:
+		if (qstr_case_eq(name, &q_cache)) {
+			info->data->perm = PERM_ANDROID_PACKAGE_CACHE;
+			info->data->under_cache = true;
+		}
+		set_top(info, parent_info);
+		break;
+	}
+}
+
+void get_derived_permission(struct dentry *parent, struct dentry *dentry)
+{
+	get_derived_permission_new(parent, dentry, &dentry->d_name);
+}
+
+static appid_t get_type(const char *name)
+{
+	const char *ext = strrchr(name, '.');
+	appid_t id;
+
+	if (ext && ext[0]) {
+		ext = &ext[1];
+		id = get_ext_gid(ext);
+		return id?:AID_MEDIA_RW;
+	}
+	return AID_MEDIA_RW;
+}
+
+void fixup_lower_ownership(struct dentry *dentry, const char *name)
+{
+	struct path path;
+	struct inode *inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+	struct sdcardfs_inode_info *info;
+	struct sdcardfs_inode_data *info_d;
+	struct sdcardfs_inode_data *info_top;
+	perm_t perm;
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+	uid_t uid = sbi->options.fs_low_uid;
+	gid_t gid = sbi->options.fs_low_gid;
+	struct iattr newattrs;
+
+	if (!sbi->options.gid_derivation)
+		return;
+
+	info = SDCARDFS_I(d_inode(dentry));
+	info_d = info->data;
+	perm = info_d->perm;
+	if (info_d->under_obb) {
+		perm = PERM_ANDROID_OBB;
+	} else if (info_d->under_cache) {
+		perm = PERM_ANDROID_PACKAGE_CACHE;
+	} else if (perm == PERM_INHERIT) {
+		info_top = top_data_get(info);
+		perm = info_top->perm;
+		data_put(info_top);
+	}
+
+	switch (perm) {
+	case PERM_ROOT:
+	case PERM_ANDROID:
+	case PERM_ANDROID_DATA:
+	case PERM_ANDROID_MEDIA:
+	case PERM_ANDROID_PACKAGE:
+	case PERM_ANDROID_PACKAGE_CACHE:
+		uid = multiuser_get_uid(info_d->userid, uid);
+		break;
+	case PERM_ANDROID_OBB:
+		uid = AID_MEDIA_OBB;
+		break;
+	case PERM_PRE_ROOT:
+	default:
+		break;
+	}
+	switch (perm) {
+	case PERM_ROOT:
+	case PERM_ANDROID:
+	case PERM_ANDROID_DATA:
+	case PERM_ANDROID_MEDIA:
+		if (S_ISDIR(d_inode(dentry)->i_mode))
+			gid = multiuser_get_uid(info_d->userid, AID_MEDIA_RW);
+		else
+			gid = multiuser_get_uid(info_d->userid, get_type(name));
+		break;
+	case PERM_ANDROID_OBB:
+		gid = AID_MEDIA_OBB;
+		break;
+	case PERM_ANDROID_PACKAGE:
+		if (uid_is_app(info_d->d_uid))
+			gid = multiuser_get_ext_gid(info_d->d_uid);
+		else
+			gid = multiuser_get_uid(info_d->userid, AID_MEDIA_RW);
+		break;
+	case PERM_ANDROID_PACKAGE_CACHE:
+		if (uid_is_app(info_d->d_uid))
+			gid = multiuser_get_ext_cache_gid(info_d->d_uid);
+		else
+			gid = multiuser_get_uid(info_d->userid, AID_MEDIA_RW);
+		break;
+	case PERM_PRE_ROOT:
+	default:
+		break;
+	}
+
+	sdcardfs_get_lower_path(dentry, &path);
+	inode = d_inode(path.dentry);
+	if (d_inode(path.dentry)->i_gid.val != gid || d_inode(path.dentry)->i_uid.val != uid) {
+retry_deleg:
+		newattrs.ia_valid = ATTR_GID | ATTR_UID | ATTR_FORCE;
+		newattrs.ia_uid = make_kuid(current_user_ns(), uid);
+		newattrs.ia_gid = make_kgid(current_user_ns(), gid);
+		if (!S_ISDIR(inode->i_mode))
+			newattrs.ia_valid |=
+				ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
+		inode_lock(inode);
+		error = security_path_chown(&path, newattrs.ia_uid, newattrs.ia_gid);
+		if (!error)
+			error = notify_change2(path.mnt, path.dentry, &newattrs, &delegated_inode);
+		inode_unlock(inode);
+		if (delegated_inode) {
+			error = break_deleg_wait(&delegated_inode);
+			if (!error)
+				goto retry_deleg;
+		}
+		if (error)
+			pr_debug("sdcardfs: Failed to touch up lower fs gid/uid for %s\n", name);
+	}
+	sdcardfs_put_lower_path(dentry, &path);
+}
+
+static int descendant_may_need_fixup(struct sdcardfs_inode_data *data,
+		struct limit_search *limit)
+{
+	if (data->perm == PERM_ROOT)
+		return (limit->flags & BY_USERID) ?
+				data->userid == limit->userid : 1;
+	if (data->perm == PERM_PRE_ROOT || data->perm == PERM_ANDROID)
+		return 1;
+	return 0;
+}
+
+static int needs_fixup(perm_t perm)
+{
+	if (perm == PERM_ANDROID_DATA || perm == PERM_ANDROID_OBB
+			|| perm == PERM_ANDROID_MEDIA)
+		return 1;
+	return 0;
+}
+
+static void __fixup_perms_recursive(struct dentry *dentry, struct limit_search *limit, int depth)
+{
+	struct dentry *child;
+	struct sdcardfs_inode_info *info;
+
+	/*
+	 * All paths will terminate their recursion on hitting PERM_ANDROID_OBB,
+	 * PERM_ANDROID_MEDIA, or PERM_ANDROID_DATA. This happens at a depth of
+	 * at most 3.
+	 */
+	WARN(depth > 3, "%s: Max expected depth exceeded!\n", __func__);
+	spin_lock_nested(&dentry->d_lock, depth);
+	if (!d_inode(dentry)) {
+		spin_unlock(&dentry->d_lock);
+		return;
+	}
+	info = SDCARDFS_I(d_inode(dentry));
+
+	if (needs_fixup(info->data->perm)) {
+		list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+			spin_lock_nested(&child->d_lock, depth + 1);
+			if (!(limit->flags & BY_NAME) || qstr_case_eq(&child->d_name, &limit->name)) {
+				if (d_inode(child)) {
+					get_derived_permission(dentry, child);
+					fixup_tmp_permissions(d_inode(child));
+					spin_unlock(&child->d_lock);
+					break;
+				}
+			}
+			spin_unlock(&child->d_lock);
+		}
+	} else if (descendant_may_need_fixup(info->data, limit)) {
+		list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+			__fixup_perms_recursive(child, limit, depth + 1);
+		}
+	}
+	spin_unlock(&dentry->d_lock);
+}
+
+void fixup_perms_recursive(struct dentry *dentry, struct limit_search *limit)
+{
+	__fixup_perms_recursive(dentry, limit, 0);
+}
+
+/* main function for updating derived permission */
+inline void update_derived_permission_lock(struct dentry *dentry)
+{
+	struct dentry *parent;
+
+	if (!dentry || !d_inode(dentry)) {
+		pr_err("sdcardfs: %s: invalid dentry\n", __func__);
+		return;
+	}
+	/* FIXME:
+	 * 1. need to check whether the dentry is updated or not
+	 * 2. remove the root dentry update
+	 */
+	if (!IS_ROOT(dentry)) {
+		parent = dget_parent(dentry);
+		if (parent) {
+			get_derived_permission(parent, dentry);
+			dput(parent);
+		}
+	}
+	fixup_tmp_permissions(d_inode(dentry));
+}
+
+int need_graft_path(struct dentry *dentry)
+{
+	int ret = 0;
+	struct dentry *parent = dget_parent(dentry);
+	struct sdcardfs_inode_info *parent_info = SDCARDFS_I(d_inode(parent));
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+	struct qstr obb = QSTR_LITERAL("obb");
+
+	if (parent_info->data->perm == PERM_ANDROID &&
+			qstr_case_eq(&dentry->d_name, &obb)) {
+
+		/* /Android/obb is the base obbpath of DERIVED_UNIFIED */
+		if (!(sbi->options.multiuser == false
+				&& parent_info->data->userid == 0)) {
+			ret = 1;
+		}
+	}
+	dput(parent);
+	return ret;
+}
+
+int is_obbpath_invalid(struct dentry *dent)
+{
+	int ret = 0;
+	struct sdcardfs_dentry_info *di = SDCARDFS_D(dent);
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dent->d_sb);
+	char *path_buf, *obbpath_s;
+	int need_put = 0;
+	struct path lower_path;
+
+	/* check the base obbpath has been changed.
+	 * this routine can check an uninitialized obb dentry as well.
+	 * regarding the uninitialized obb, refer to the sdcardfs_mkdir()
+	 */
+	spin_lock(&di->lock);
+	if (di->orig_path.dentry) {
+		if (!di->lower_path.dentry) {
+			ret = 1;
+		} else {
+			path_get(&di->lower_path);
+
+			path_buf = kmalloc(PATH_MAX, GFP_ATOMIC);
+			if (!path_buf) {
+				ret = 1;
+				pr_err("sdcardfs: fail to allocate path_buf in %s.\n", __func__);
+			} else {
+				obbpath_s = d_path(&di->lower_path, path_buf, PATH_MAX);
+				if (d_unhashed(di->lower_path.dentry) ||
+					!str_case_eq(sbi->obbpath_s, obbpath_s)) {
+					ret = 1;
+				}
+				kfree(path_buf);
+			}
+
+			pathcpy(&lower_path, &di->lower_path);
+			need_put = 1;
+		}
+	}
+	spin_unlock(&di->lock);
+	if (need_put)
+		path_put(&lower_path);
+	return ret;
+}
+
+int is_base_obbpath(struct dentry *dentry)
+{
+	int ret = 0;
+	struct dentry *parent = dget_parent(dentry);
+	struct sdcardfs_inode_info *parent_info = SDCARDFS_I(d_inode(parent));
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+	struct qstr q_obb = QSTR_LITERAL("obb");
+
+	spin_lock(&SDCARDFS_D(dentry)->lock);
+	if (sbi->options.multiuser) {
+		if (parent_info->data->perm == PERM_PRE_ROOT &&
+				qstr_case_eq(&dentry->d_name, &q_obb)) {
+			ret = 1;
+		}
+	} else  if (parent_info->data->perm == PERM_ANDROID &&
+			qstr_case_eq(&dentry->d_name, &q_obb)) {
+		ret = 1;
+	}
+	spin_unlock(&SDCARDFS_D(dentry)->lock);
+	return ret;
+}
+
+/* The lower_path will be stored to the dentry's orig_path
+ * and the base obbpath will be copyed to the lower_path variable.
+ * if an error returned, there's no change in the lower_path
+ * returns: -ERRNO if error (0: no error)
+ */
+int setup_obb_dentry(struct dentry *dentry, struct path *lower_path)
+{
+	int err = 0;
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+	struct path obbpath;
+
+	/* A local obb dentry must have its own orig_path to support rmdir
+	 * and mkdir of itself. Usually, we expect that the sbi->obbpath
+	 * is avaiable on this stage.
+	 */
+	sdcardfs_set_orig_path(dentry, lower_path);
+
+	err = kern_path(sbi->obbpath_s,
+			LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &obbpath);
+
+	if (!err) {
+		/* the obbpath base has been found */
+		pathcpy(lower_path, &obbpath);
+	} else {
+		/* if the sbi->obbpath is not available, we can optionally
+		 * setup the lower_path with its orig_path.
+		 * but, the current implementation just returns an error
+		 * because the sdcard daemon also regards this case as
+		 * a lookup fail.
+		 */
+		pr_info("sdcardfs: the sbi->obbpath is not available\n");
+	}
+	return err;
+}
+
+