include/linux/backing-file.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Common helpers for stackable filesystems and backing files.
 *
 * Copyright (C) 2023 CTERA Networks.
 */

#ifndef _LINUX_BACKING_FILE_H
#define _LINUX_BACKING_FILE_H

#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fs.h>

struct backing_file_ctx {
	const struct cred *cred;
	struct file *user_file;
	void (*accessed)(struct file *);
	void (*end_write)(struct file *);
};

struct file *backing_file_open(const struct path *user_path, int flags,
			       const struct path *real_path,
			       const struct cred *cred);
ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
			       struct kiocb *iocb, int flags,
			       struct backing_file_ctx *ctx);
ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
				struct kiocb *iocb, int flags,
				struct backing_file_ctx *ctx);
ssize_t backing_file_splice_read(struct file *in, loff_t *ppos,
				 struct pipe_inode_info *pipe, size_t len,
				 unsigned int flags,
				 struct backing_file_ctx *ctx);
ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
				  struct file *out, loff_t *ppos, size_t len,
				  unsigned int flags,
				  struct backing_file_ctx *ctx);
int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
		      struct backing_file_ctx *ctx);

#endif /* _LINUX_BACKING_FILE_H */