diff -drupN a/fs/sdcardfs/file.c b/fs/sdcardfs/file.c
--- a/fs/sdcardfs/file.c	1970-01-01 03:00:00.000000000 +0300
+++ b/fs/sdcardfs/file.c	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,467 @@
+/*
+ * fs/sdcardfs/file.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"
+#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
+#include <linux/backing-dev.h>
+#endif
+
+static ssize_t sdcardfs_read(struct file *file, char __user *buf,
+			   size_t count, loff_t *ppos)
+{
+	int err;
+	struct file *lower_file;
+	struct dentry *dentry = file->f_path.dentry;
+#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
+	struct backing_dev_info *bdi;
+#endif
+
+	lower_file = sdcardfs_lower_file(file);
+
+#ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
+	if (file->f_mode & FMODE_NOACTIVE) {
+		if (!(lower_file->f_mode & FMODE_NOACTIVE)) {
+			bdi = lower_file->f_mapping->backing_dev_info;
+			lower_file->f_ra.ra_pages = bdi->ra_pages * 2;
+			spin_lock(&lower_file->f_lock);
+			lower_file->f_mode |= FMODE_NOACTIVE;
+			spin_unlock(&lower_file->f_lock);
+		}
+	}
+#endif
+
+	err = vfs_read(lower_file, buf, count, ppos);
+	/* update our inode atime upon a successful lower read */
+	if (err >= 0)
+		fsstack_copy_attr_atime(d_inode(dentry),
+					file_inode(lower_file));
+
+	return err;
+}
+
+static ssize_t sdcardfs_write(struct file *file, const char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	int err;
+	struct file *lower_file;
+	struct dentry *dentry = file->f_path.dentry;
+	struct inode *inode = d_inode(dentry);
+
+	/* check disk space */
+	if (!check_min_free_space(dentry, count, 0)) {
+		pr_err("No minimum free space.\n");
+		return -ENOSPC;
+	}
+
+	lower_file = sdcardfs_lower_file(file);
+	err = vfs_write(lower_file, buf, count, ppos);
+	/* update our inode times+sizes upon a successful lower write */
+	if (err >= 0) {
+		if (sizeof(loff_t) > sizeof(long))
+			inode_lock(inode);
+		fsstack_copy_inode_size(inode, file_inode(lower_file));
+		fsstack_copy_attr_times(inode, file_inode(lower_file));
+		if (sizeof(loff_t) > sizeof(long))
+			inode_unlock(inode);
+	}
+
+	return err;
+}
+
+static int sdcardfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	int err;
+	struct file *lower_file = NULL;
+	struct dentry *dentry = file->f_path.dentry;
+
+	lower_file = sdcardfs_lower_file(file);
+
+	lower_file->f_pos = file->f_pos;
+	err = iterate_dir(lower_file, ctx);
+	file->f_pos = lower_file->f_pos;
+	if (err >= 0)		/* copy the atime */
+		fsstack_copy_attr_atime(d_inode(dentry),
+					file_inode(lower_file));
+	return err;
+}
+
+static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
+				  unsigned long arg)
+{
+	long err = -ENOTTY;
+	struct file *lower_file;
+	const struct cred *saved_cred = NULL;
+	struct dentry *dentry = file->f_path.dentry;
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+
+	lower_file = sdcardfs_lower_file(file);
+
+	/* XXX: use vfs_ioctl if/when VFS exports it */
+	if (!lower_file || !lower_file->f_op)
+		goto out;
+
+	/* save current_cred and override it */
+	saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	if (lower_file->f_op->unlocked_ioctl)
+		err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
+
+	/* some ioctls can change inode attributes (EXT2_IOC_SETFLAGS) */
+	if (!err)
+		sdcardfs_copy_and_fix_attrs(file_inode(file),
+				      file_inode(lower_file));
+	revert_fsids(saved_cred);
+out:
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	long err = -ENOTTY;
+	struct file *lower_file;
+	const struct cred *saved_cred = NULL;
+	struct dentry *dentry = file->f_path.dentry;
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+
+	lower_file = sdcardfs_lower_file(file);
+
+	/* XXX: use vfs_ioctl if/when VFS exports it */
+	if (!lower_file || !lower_file->f_op)
+		goto out;
+
+	/* save current_cred and override it */
+	saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	if (lower_file->f_op->compat_ioctl)
+		err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
+
+	revert_fsids(saved_cred);
+out:
+	return err;
+}
+#endif
+
+static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	int err = 0;
+	bool willwrite;
+	struct file *lower_file;
+	const struct vm_operations_struct *saved_vm_ops = NULL;
+
+	/* this might be deferred to mmap's writepage */
+	willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
+
+	/*
+	 * File systems which do not implement ->writepage may use
+	 * generic_file_readonly_mmap as their ->mmap op.  If you call
+	 * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
+	 * But we cannot call the lower ->mmap op, so we can't tell that
+	 * writeable mappings won't work.  Therefore, our only choice is to
+	 * check if the lower file system supports the ->writepage, and if
+	 * not, return EINVAL (the same error that
+	 * generic_file_readonly_mmap returns in that case).
+	 */
+	lower_file = sdcardfs_lower_file(file);
+	if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
+		err = -EINVAL;
+		pr_err("sdcardfs: lower file system does not support writeable mmap\n");
+		goto out;
+	}
+
+	/*
+	 * find and save lower vm_ops.
+	 *
+	 * XXX: the VFS should have a cleaner way of finding the lower vm_ops
+	 */
+	if (!SDCARDFS_F(file)->lower_vm_ops) {
+		err = lower_file->f_op->mmap(lower_file, vma);
+		if (err) {
+			pr_err("sdcardfs: lower mmap failed %d\n", err);
+			goto out;
+		}
+		saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
+	}
+
+	/*
+	 * Next 3 lines are all I need from generic_file_mmap.  I definitely
+	 * don't want its test for ->readpage which returns -ENOEXEC.
+	 */
+	file_accessed(file);
+	vma->vm_ops = &sdcardfs_vm_ops;
+
+	file->f_mapping->a_ops = &sdcardfs_aops; /* set our aops */
+	if (!SDCARDFS_F(file)->lower_vm_ops) /* save for our ->fault */
+		SDCARDFS_F(file)->lower_vm_ops = saved_vm_ops;
+	vma->vm_private_data = file;
+	get_file(lower_file);
+	vma->vm_file = lower_file;
+
+out:
+	return err;
+}
+
+static int sdcardfs_open(struct inode *inode, struct file *file)
+{
+	int err = 0;
+	struct file *lower_file = NULL;
+	struct path lower_path;
+	struct dentry *dentry = file->f_path.dentry;
+	struct dentry *parent = dget_parent(dentry);
+	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
+	const struct cred *saved_cred = NULL;
+
+	/* don't open unhashed/deleted files */
+	if (d_unhashed(dentry)) {
+		err = -ENOENT;
+		goto out_err;
+	}
+
+	if (!check_caller_access_to_name(d_inode(parent), &dentry->d_name)) {
+		err = -EACCES;
+		goto out_err;
+	}
+
+	/* save current_cred and override it */
+	saved_cred = override_fsids(sbi, SDCARDFS_I(inode)->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out_err;
+	}
+
+	file->private_data =
+		kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL);
+	if (!SDCARDFS_F(file)) {
+		err = -ENOMEM;
+		goto out_revert_cred;
+	}
+
+	/* open lower object and link sdcardfs's file struct to lower's */
+	sdcardfs_get_lower_path(file->f_path.dentry, &lower_path);
+	lower_file = dentry_open(&lower_path, file->f_flags, current_cred());
+	path_put(&lower_path);
+	if (IS_ERR(lower_file)) {
+		err = PTR_ERR(lower_file);
+		lower_file = sdcardfs_lower_file(file);
+		if (lower_file) {
+			sdcardfs_set_lower_file(file, NULL);
+			fput(lower_file); /* fput calls dput for lower_dentry */
+		}
+	} else {
+		sdcardfs_set_lower_file(file, lower_file);
+	}
+
+	if (err)
+		kfree(SDCARDFS_F(file));
+	else
+		sdcardfs_copy_and_fix_attrs(inode, sdcardfs_lower_inode(inode));
+
+out_revert_cred:
+	revert_fsids(saved_cred);
+out_err:
+	dput(parent);
+	return err;
+}
+
+static int sdcardfs_flush(struct file *file, fl_owner_t id)
+{
+	int err = 0;
+	struct file *lower_file = NULL;
+
+	lower_file = sdcardfs_lower_file(file);
+	if (lower_file && lower_file->f_op && lower_file->f_op->flush) {
+		filemap_write_and_wait(file->f_mapping);
+		err = lower_file->f_op->flush(lower_file, id);
+	}
+
+	return err;
+}
+
+/* release all lower object references & free the file info structure */
+static int sdcardfs_file_release(struct inode *inode, struct file *file)
+{
+	struct file *lower_file;
+
+	lower_file = sdcardfs_lower_file(file);
+	if (lower_file) {
+		sdcardfs_set_lower_file(file, NULL);
+		fput(lower_file);
+	}
+
+	kfree(SDCARDFS_F(file));
+	return 0;
+}
+
+static int sdcardfs_fsync(struct file *file, loff_t start, loff_t end,
+			int datasync)
+{
+	int err;
+	struct file *lower_file;
+	struct path lower_path;
+	struct dentry *dentry = file->f_path.dentry;
+
+	err = __generic_file_fsync(file, start, end, datasync);
+	if (err)
+		goto out;
+
+	lower_file = sdcardfs_lower_file(file);
+	sdcardfs_get_lower_path(dentry, &lower_path);
+	err = vfs_fsync_range(lower_file, start, end, datasync);
+	sdcardfs_put_lower_path(dentry, &lower_path);
+out:
+	return err;
+}
+
+static int sdcardfs_fasync(int fd, struct file *file, int flag)
+{
+	int err = 0;
+	struct file *lower_file = NULL;
+
+	lower_file = sdcardfs_lower_file(file);
+	if (lower_file->f_op && lower_file->f_op->fasync)
+		err = lower_file->f_op->fasync(fd, lower_file, flag);
+
+	return err;
+}
+
+/*
+ * Sdcardfs cannot use generic_file_llseek as ->llseek, because it would
+ * only set the offset of the upper file.  So we have to implement our
+ * own method to set both the upper and lower file offsets
+ * consistently.
+ */
+static loff_t sdcardfs_file_llseek(struct file *file, loff_t offset, int whence)
+{
+	int err;
+	struct file *lower_file;
+
+	err = generic_file_llseek(file, offset, whence);
+	if (err < 0)
+		goto out;
+
+	lower_file = sdcardfs_lower_file(file);
+	err = generic_file_llseek(lower_file, offset, whence);
+
+out:
+	return err;
+}
+
+/*
+ * Sdcardfs read_iter, redirect modified iocb to lower read_iter
+ */
+ssize_t sdcardfs_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+	int err;
+	struct file *file = iocb->ki_filp, *lower_file;
+
+	lower_file = sdcardfs_lower_file(file);
+	if (!lower_file->f_op->read_iter) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	get_file(lower_file); /* prevent lower_file from being released */
+	iocb->ki_filp = lower_file;
+	err = lower_file->f_op->read_iter(iocb, iter);
+	iocb->ki_filp = file;
+	fput(lower_file);
+	/* update upper inode atime as needed */
+	if (err >= 0 || err == -EIOCBQUEUED)
+		fsstack_copy_attr_atime(file->f_path.dentry->d_inode,
+					file_inode(lower_file));
+out:
+	return err;
+}
+
+/*
+ * Sdcardfs write_iter, redirect modified iocb to lower write_iter
+ */
+ssize_t sdcardfs_write_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+	int err;
+	struct file *file = iocb->ki_filp, *lower_file;
+	struct inode *inode = file->f_path.dentry->d_inode;
+
+	lower_file = sdcardfs_lower_file(file);
+	if (!lower_file->f_op->write_iter) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	get_file(lower_file); /* prevent lower_file from being released */
+	iocb->ki_filp = lower_file;
+	err = lower_file->f_op->write_iter(iocb, iter);
+	iocb->ki_filp = file;
+	fput(lower_file);
+	/* update upper inode times/sizes as needed */
+	if (err >= 0 || err == -EIOCBQUEUED) {
+		if (sizeof(loff_t) > sizeof(long))
+			inode_lock(inode);
+		fsstack_copy_inode_size(inode, file_inode(lower_file));
+		fsstack_copy_attr_times(inode, file_inode(lower_file));
+		if (sizeof(loff_t) > sizeof(long))
+			inode_unlock(inode);
+	}
+out:
+	return err;
+}
+
+const struct file_operations sdcardfs_main_fops = {
+	.llseek		= generic_file_llseek,
+	.read		= sdcardfs_read,
+	.write		= sdcardfs_write,
+	.unlocked_ioctl	= sdcardfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= sdcardfs_compat_ioctl,
+#endif
+	.mmap		= sdcardfs_mmap,
+	.open		= sdcardfs_open,
+	.flush		= sdcardfs_flush,
+	.release	= sdcardfs_file_release,
+	.fsync		= sdcardfs_fsync,
+	.fasync		= sdcardfs_fasync,
+	.read_iter	= sdcardfs_read_iter,
+	.write_iter	= sdcardfs_write_iter,
+};
+
+/* trimmed directory options */
+const struct file_operations sdcardfs_dir_fops = {
+	.llseek		= sdcardfs_file_llseek,
+	.read		= generic_read_dir,
+	.iterate	= sdcardfs_readdir,
+	.unlocked_ioctl	= sdcardfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= sdcardfs_compat_ioctl,
+#endif
+	.open		= sdcardfs_open,
+	.release	= sdcardfs_file_release,
+	.flush		= sdcardfs_flush,
+	.fsync		= sdcardfs_fsync,
+	.fasync		= sdcardfs_fasync,
+};