diff -drupN a/fs/sdcardfs/lookup.c b/fs/sdcardfs/lookup.c
--- a/fs/sdcardfs/lookup.c	1970-01-01 03:00:00.000000000 +0300
+++ b/fs/sdcardfs/lookup.c	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,469 @@
+/*
+ * fs/sdcardfs/lookup.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/delay.h"
+
+/* The dentry cache is just so we have properly sized dentries */
+static struct kmem_cache *sdcardfs_dentry_cachep;
+
+int sdcardfs_init_dentry_cache(void)
+{
+	sdcardfs_dentry_cachep =
+		kmem_cache_create("sdcardfs_dentry",
+				  sizeof(struct sdcardfs_dentry_info),
+				  0, SLAB_RECLAIM_ACCOUNT, NULL);
+
+	return sdcardfs_dentry_cachep ? 0 : -ENOMEM;
+}
+
+void sdcardfs_destroy_dentry_cache(void)
+{
+	kmem_cache_destroy(sdcardfs_dentry_cachep);
+}
+
+void free_dentry_private_data(struct dentry *dentry)
+{
+	kmem_cache_free(sdcardfs_dentry_cachep, dentry->d_fsdata);
+	dentry->d_fsdata = NULL;
+}
+
+/* allocate new dentry private data */
+int new_dentry_private_data(struct dentry *dentry)
+{
+	struct sdcardfs_dentry_info *info = SDCARDFS_D(dentry);
+
+	/* use zalloc to init dentry_info.lower_path */
+	info = kmem_cache_zalloc(sdcardfs_dentry_cachep, GFP_ATOMIC);
+	if (!info)
+		return -ENOMEM;
+
+	spin_lock_init(&info->lock);
+	dentry->d_fsdata = info;
+
+	return 0;
+}
+
+struct inode_data {
+	struct inode *lower_inode;
+	userid_t id;
+};
+
+static int sdcardfs_inode_test(struct inode *inode, void *candidate_data/*void *candidate_lower_inode*/)
+{
+	struct inode *current_lower_inode = sdcardfs_lower_inode(inode);
+	userid_t current_userid = SDCARDFS_I(inode)->data->userid;
+
+	if (current_lower_inode == ((struct inode_data *)candidate_data)->lower_inode &&
+			current_userid == ((struct inode_data *)candidate_data)->id)
+		return 1; /* found a match */
+	else
+		return 0; /* no match */
+}
+
+static int sdcardfs_inode_set(struct inode *inode, void *lower_inode)
+{
+	/* we do actual inode initialization in sdcardfs_iget */
+	return 0;
+}
+
+struct inode *sdcardfs_iget(struct super_block *sb, struct inode *lower_inode, userid_t id)
+{
+	struct sdcardfs_inode_info *info;
+	struct inode_data data;
+	struct inode *inode; /* the new inode to return */
+
+	if (!igrab(lower_inode))
+		return ERR_PTR(-ESTALE);
+
+	data.id = id;
+	data.lower_inode = lower_inode;
+	inode = iget5_locked(sb, /* our superblock */
+			     /*
+			      * hashval: we use inode number, but we can
+			      * also use "(unsigned long)lower_inode"
+			      * instead.
+			      */
+			     lower_inode->i_ino, /* hashval */
+			     sdcardfs_inode_test, /* inode comparison function */
+			     sdcardfs_inode_set, /* inode init function */
+			     &data); /* data passed to test+set fxns */
+	if (!inode) {
+		iput(lower_inode);
+		return ERR_PTR(-ENOMEM);
+	}
+	/* if found a cached inode, then just return it (after iput) */
+	if (!(inode->i_state & I_NEW)) {
+		iput(lower_inode);
+		return inode;
+	}
+
+	/* initialize new inode */
+	info = SDCARDFS_I(inode);
+
+	inode->i_ino = lower_inode->i_ino;
+	sdcardfs_set_lower_inode(inode, lower_inode);
+
+	inode->i_version++;
+
+	/* use different set of inode ops for symlinks & directories */
+	if (S_ISDIR(lower_inode->i_mode))
+		inode->i_op = &sdcardfs_dir_iops;
+	else if (S_ISLNK(lower_inode->i_mode))
+		inode->i_op = &sdcardfs_symlink_iops;
+	else
+		inode->i_op = &sdcardfs_main_iops;
+
+	/* use different set of file ops for directories */
+	if (S_ISDIR(lower_inode->i_mode))
+		inode->i_fop = &sdcardfs_dir_fops;
+	else
+		inode->i_fop = &sdcardfs_main_fops;
+
+	inode->i_mapping->a_ops = &sdcardfs_aops;
+
+	inode->i_atime.tv_sec = 0;
+	inode->i_atime.tv_nsec = 0;
+	inode->i_mtime.tv_sec = 0;
+	inode->i_mtime.tv_nsec = 0;
+	inode->i_ctime.tv_sec = 0;
+	inode->i_ctime.tv_nsec = 0;
+
+	/* properly initialize special inodes */
+	if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
+	    S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
+		init_special_inode(inode, lower_inode->i_mode,
+				   lower_inode->i_rdev);
+
+	/* all well, copy inode attributes */
+	sdcardfs_copy_and_fix_attrs(inode, lower_inode);
+	fsstack_copy_inode_size(inode, lower_inode);
+
+	unlock_new_inode(inode);
+	return inode;
+}
+
+/*
+ * Helper interpose routine, called directly by ->lookup to handle
+ * spliced dentries.
+ */
+static struct dentry *__sdcardfs_interpose(struct dentry *dentry,
+					 struct super_block *sb,
+					 struct path *lower_path,
+					 userid_t id)
+{
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct super_block *lower_sb;
+	struct dentry *ret_dentry;
+
+	lower_inode = d_inode(lower_path->dentry);
+	lower_sb = sdcardfs_lower_super(sb);
+
+	/* check that the lower file system didn't cross a mount point */
+	if (lower_inode->i_sb != lower_sb) {
+		ret_dentry = ERR_PTR(-EXDEV);
+		goto out;
+	}
+
+	/*
+	 * We allocate our new inode below by calling sdcardfs_iget,
+	 * which will initialize some of the new inode's fields
+	 */
+
+	/* inherit lower inode number for sdcardfs's inode */
+	inode = sdcardfs_iget(sb, lower_inode, id);
+	if (IS_ERR(inode)) {
+		ret_dentry = ERR_CAST(inode);
+		goto out;
+	}
+
+	ret_dentry = d_splice_alias(inode, dentry);
+	dentry = ret_dentry ?: dentry;
+	if (!IS_ERR(dentry))
+		update_derived_permission_lock(dentry);
+out:
+	return ret_dentry;
+}
+
+/*
+ * Connect an sdcardfs inode dentry/inode with several lower ones.  This is
+ * the classic stackable file system "vnode interposition" action.
+ *
+ * @dentry: sdcardfs's dentry which interposes on lower one
+ * @sb: sdcardfs's super_block
+ * @lower_path: the lower path (caller does path_get/put)
+ */
+int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb,
+		     struct path *lower_path, userid_t id)
+{
+	struct dentry *ret_dentry;
+
+	ret_dentry = __sdcardfs_interpose(dentry, sb, lower_path, id);
+	return PTR_ERR(ret_dentry);
+}
+
+struct sdcardfs_name_data {
+	struct dir_context ctx;
+	const struct qstr *to_find;
+	char *name;
+	bool found;
+};
+
+static int sdcardfs_name_match(struct dir_context *ctx, const char *name,
+		int namelen, loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct sdcardfs_name_data *buf = container_of(ctx, struct sdcardfs_name_data, ctx);
+	struct qstr candidate = QSTR_INIT(name, namelen);
+
+	if (qstr_case_eq(buf->to_find, &candidate)) {
+		memcpy(buf->name, name, namelen);
+		buf->name[namelen] = 0;
+		buf->found = true;
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Main driver function for sdcardfs's lookup.
+ *
+ * Returns: NULL (ok), ERR_PTR if an error occurred.
+ * Fills in lower_parent_path with <dentry,mnt> on success.
+ */
+static struct dentry *__sdcardfs_lookup(struct dentry *dentry,
+		unsigned int flags, struct path *lower_parent_path, userid_t id)
+{
+	int err = 0;
+	struct vfsmount *lower_dir_mnt;
+	struct dentry *lower_dir_dentry = NULL;
+	struct dentry *lower_dentry;
+	const struct qstr *name;
+	struct path lower_path;
+	struct qstr dname;
+	struct dentry *ret_dentry = NULL;
+	struct sdcardfs_sb_info *sbi;
+
+	sbi = SDCARDFS_SB(dentry->d_sb);
+	/* must initialize dentry operations */
+	d_set_d_op(dentry, &sdcardfs_ci_dops);
+
+	if (IS_ROOT(dentry))
+		goto out;
+
+	name = &dentry->d_name;
+
+	/* now start the actual lookup procedure */
+	lower_dir_dentry = lower_parent_path->dentry;
+	lower_dir_mnt = lower_parent_path->mnt;
+
+	/* Use vfs_path_lookup to check if the dentry exists or not */
+	err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name->name, 0,
+				&lower_path);
+	/* check for other cases */
+	if (err == -ENOENT) {
+		struct file *file;
+		const struct cred *cred = current_cred();
+
+		struct sdcardfs_name_data buffer = {
+			.ctx.actor = sdcardfs_name_match,
+			.to_find = name,
+			.name = __getname(),
+			.found = false,
+		};
+
+		if (!buffer.name) {
+			err = -ENOMEM;
+			goto out;
+		}
+		file = dentry_open(lower_parent_path, O_RDONLY, cred);
+		if (IS_ERR(file)) {
+			err = PTR_ERR(file);
+			goto put_name;
+		}
+		err = iterate_dir(file, &buffer.ctx);
+		fput(file);
+		if (err)
+			goto put_name;
+
+		if (buffer.found)
+			err = vfs_path_lookup(lower_dir_dentry,
+						lower_dir_mnt,
+						buffer.name, 0,
+						&lower_path);
+		else
+			err = -ENOENT;
+put_name:
+		__putname(buffer.name);
+	}
+
+	/* no error: handle positive dentries */
+	if (!err) {
+		/* check if the dentry is an obb dentry
+		 * if true, the lower_inode must be replaced with
+		 * the inode of the graft path
+		 */
+
+		if (need_graft_path(dentry)) {
+
+			/* setup_obb_dentry()
+			 * 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)
+			 */
+			err = setup_obb_dentry(dentry, &lower_path);
+
+			if (err) {
+				/* 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: base obbpath is not available\n");
+				sdcardfs_put_reset_orig_path(dentry);
+				goto out;
+			}
+		}
+
+		sdcardfs_set_lower_path(dentry, &lower_path);
+		ret_dentry =
+			__sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id);
+		if (IS_ERR(ret_dentry)) {
+			err = PTR_ERR(ret_dentry);
+			 /* path_put underlying path on error */
+			sdcardfs_put_reset_lower_path(dentry);
+		}
+		goto out;
+	}
+
+	/*
+	 * We don't consider ENOENT an error, and we want to return a
+	 * negative dentry.
+	 */
+	if (err && err != -ENOENT)
+		goto out;
+
+	/* instatiate a new negative dentry */
+	dname.name = name->name;
+	dname.len = name->len;
+
+	/* See if the low-level filesystem might want
+	 * to use its own hash
+	 */
+	lower_dentry = d_hash_and_lookup(lower_dir_dentry, &dname);
+	if (IS_ERR(lower_dentry))
+		return lower_dentry;
+	if (!lower_dentry) {
+		/* We called vfs_path_lookup earlier, and did not get a negative
+		 * dentry then. Don't confuse the lower filesystem by forcing
+		 * one on it now...
+		 */
+		err = -ENOENT;
+		goto out;
+	}
+
+	lower_path.dentry = lower_dentry;
+	lower_path.mnt = mntget(lower_dir_mnt);
+	sdcardfs_set_lower_path(dentry, &lower_path);
+
+	/*
+	 * If the intent is to create a file, then don't return an error, so
+	 * the VFS will continue the process of making this negative dentry
+	 * into a positive one.
+	 */
+	if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
+		err = 0;
+
+out:
+	if (err)
+		return ERR_PTR(err);
+	return ret_dentry;
+}
+
+/*
+ * On success:
+ * fills dentry object appropriate values and returns NULL.
+ * On fail (== error)
+ * returns error ptr
+ *
+ * @dir : Parent inode.
+ * @dentry : Target dentry to lookup. we should set each of fields.
+ *	     (dentry->d_name is initialized already)
+ * @nd : nameidata of parent inode
+ */
+struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry,
+			     unsigned int flags)
+{
+	struct dentry *ret = NULL, *parent;
+	struct path lower_parent_path;
+	int err = 0;
+	const struct cred *saved_cred = NULL;
+
+	parent = dget_parent(dentry);
+
+	if (!check_caller_access_to_name(d_inode(parent), &dentry->d_name)) {
+		ret = ERR_PTR(-EACCES);
+		goto out_err;
+	}
+
+	/* save current_cred and override it */
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+						SDCARDFS_I(dir)->data);
+	if (!saved_cred) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_err;
+	}
+
+	sdcardfs_get_lower_path(parent, &lower_parent_path);
+
+	/* allocate dentry private data.  We free it in ->d_release */
+	err = new_dentry_private_data(dentry);
+	if (err) {
+		ret = ERR_PTR(err);
+		goto out;
+	}
+
+	ret = __sdcardfs_lookup(dentry, flags, &lower_parent_path,
+				SDCARDFS_I(dir)->data->userid);
+	if (IS_ERR(ret))
+		goto out;
+	if (ret)
+		dentry = ret;
+	if (d_inode(dentry)) {
+		fsstack_copy_attr_times(d_inode(dentry),
+					sdcardfs_lower_inode(d_inode(dentry)));
+		/* get derived permission */
+		get_derived_permission(parent, dentry);
+		fixup_tmp_permissions(d_inode(dentry));
+		fixup_lower_ownership(dentry, dentry->d_name.name);
+	}
+	/* update parent directory's atime */
+	fsstack_copy_attr_atime(d_inode(parent),
+				sdcardfs_lower_inode(d_inode(parent)));
+
+out:
+	sdcardfs_put_lower_path(parent, &lower_parent_path);
+	revert_fsids(saved_cred);
+out_err:
+	dput(parent);
+	return ret;
+}