/*
 * loop_main.h
 *
 * Written by Theodore Ts'o, 3/29/93.
 *
 * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
 * permitted under the GNU General Public License.
 */
#ifndef _LINUX_LOOP_H
#define _LINUX_LOOP_H

#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/kthread.h>
#include <uapi/linux/loop.h>

#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#endif

#include "loop_file_fmt.h"

// See: https://www.kernel.org/doc/Documentation/admin-guide/devices.txt
#define XLOOP_MAJOR          120
#define XLOOP_CTRL_MINOR     142

/* Possible states of device */
enum {
	Lo_unbound,
	Lo_bound,
	Lo_rundown,
};

struct loop_func_table;

struct xloop_info {
	int		   lo_number;		/* ioctl r/o */
	__kernel_old_dev_t lo_device; 		/* ioctl r/o */
	unsigned long	   lo_inode; 		/* ioctl r/o */
	__kernel_old_dev_t lo_rdevice; 		/* ioctl r/o */
	int		   lo_offset;
	int		   lo_encrypt_type;
	int		   lo_encrypt_key_size; 	/* ioctl w/o */
	int		   lo_flags;			/* ioctl r/o */
	char		   lo_name[LO_NAME_SIZE];
	unsigned char	   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
	unsigned long	   lo_init[2];
	char		   reserved[4];
	int		   lo_file_fmt_type;
};

struct xloop_info64 {
	__u64		   lo_device;			/* ioctl r/o */
	__u64		   lo_inode;			/* ioctl r/o */
	__u64		   lo_rdevice;			/* ioctl r/o */
	__u64		   lo_offset;
	__u64		   lo_sizelimit;/* bytes, 0 == max available */
	__u32		   lo_number;			/* ioctl r/o */
	__u32		   lo_encrypt_type;
	__u32		   lo_encrypt_key_size;		/* ioctl w/o */
	__u32		   lo_flags;			/* ioctl r/o */
	__u8		   lo_file_name[LO_NAME_SIZE];
	__u8		   lo_crypt_name[LO_NAME_SIZE];
	__u8		   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
	__u64		   lo_init[2];
	__u32		   lo_file_fmt_type;
} __attribute__((packed));

struct loop_device {
	int		lo_number;
	atomic_t	lo_refcnt;
	loff_t		lo_offset;
	loff_t		lo_sizelimit;
	int		lo_flags;
	int		(*transfer)(struct loop_device *, int cmd,
				    struct page *raw_page, unsigned raw_off,
				    struct page *loop_page, unsigned loop_off,
				    int size, sector_t real_block);
	char		lo_file_name[LO_NAME_SIZE];
	char		lo_crypt_name[LO_NAME_SIZE];
	char		lo_encrypt_key[LO_KEY_SIZE];
	int		lo_encrypt_key_size;
	struct loop_func_table *lo_encryption;
	__u32           lo_init[2];
	kuid_t		lo_key_owner;	/* Who set the key */
	int		(*ioctl)(struct loop_device *, int cmd, 
				 unsigned long arg); 

	struct loop_file_fmt *lo_fmt;

	struct file *	lo_backing_file;
	struct block_device *lo_device;
	void		*key_data; 

	gfp_t		old_gfp_mask;

	spinlock_t		lo_lock;
	int			lo_state;
	struct kthread_worker	worker;
	struct task_struct	*worker_task;
	bool			use_dio;
	bool			sysfs_inited;

	struct request_queue	*lo_queue;
	struct blk_mq_tag_set	tag_set;
	struct gendisk		*lo_disk;

#ifdef CONFIG_DEBUG_FS
	struct dentry *lo_dbgfs_dir;
#endif
};

struct loop_cmd {
	struct kthread_work work;
	bool use_aio; /* use AIO interface to handle I/O */
	atomic_t ref; /* only for aio */
	long ret;
	struct kiocb iocb;
	struct bio_vec *bvec;
	struct cgroup_subsys_state *css;
};

/* Support for loadable transfer modules */
struct loop_func_table {
	int number;	/* filter type */ 
	int (*transfer)(struct loop_device *lo, int cmd,
			struct page *raw_page, unsigned raw_off,
			struct page *loop_page, unsigned loop_off,
			int size, sector_t real_block);
	int (*init)(struct loop_device *, const struct xloop_info64 *);
	/* release is called from loop_unregister_transfer or clr_fd */
	int (*release)(struct loop_device *); 
	int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
	struct module *owner;
}; 

int xloop_register_transfer(struct loop_func_table *funcs);
int xloop_unregister_transfer(int number);

#endif