/* SPDX-License-Identifier: GPL-2.0 */
/*
* loop_file_fmt.h
*
* File format subsystem for the loop device module.
*
* Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
*/
#ifndef _LINUX_LOOP_FILE_FMT_H
#define _LINUX_LOOP_FILE_FMT_H
#include "loop_main.h"
struct loop_file_fmt;
/**
* struct loop_file_fmt_ops - File format subsystem operations
*
* Data structure representing the file format subsystem interface.
*/
struct loop_file_fmt_ops {
/**
* @init: Initialization callback function
*/
int (*init) (struct loop_file_fmt *lo_fmt);
/**
* @exit: Release callback function
*/
void (*exit) (struct loop_file_fmt *lo_fmt);
/**
* @read: Read IO callback function
*/
int (*read) (struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* @write: Write IO callback function
*/
int (*write) (struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* @read_aio: Asynchronous read IO callback function
*/
int (*read_aio) (struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* @write_aio: Asynchronous write IO callback function
*/
int (*write_aio) (struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* @discard: Discard IO callback function
*/
int (*discard) (struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* @flush: Flush callback function
*/
int (*flush) (struct loop_file_fmt *lo_fmt);
/**
* @sector_size: Get sector size callback function
*/
loff_t (*sector_size) (struct loop_file_fmt *lo_fmt);
};
/**
* struct loop_file_fmt_driver - File format subsystem driver
*
* Data structure to implement file format drivers for the file format
* subsystem.
*/
struct loop_file_fmt_driver {
/**
* @name: Name of the file format driver
*/
const char *name;
/**
* @file_fmt_type: Loop file format type of the file format driver
*/
const u32 file_fmt_type;
/**
* @ops: Driver's implemented file format operations
*/
struct loop_file_fmt_ops *ops;
/**
* @ops: Owner of the file format driver
*/
struct module *owner;
};
/*
* states of the file format
*
* transitions:
* loop_file_fmt_init(...)
* ---> uninitialized ------------------------------> initialized
* loop_file_fmt_exit(...)
* initialized ------------------------------> uninitialized
* loop_file_fmt_read(...)
* initialized ------------------------------> initialized
* loop_file_fmt_read_aio(...)
* initialized ------------------------------> initialized
* loop_file_fmt_write(...)
* initialized ------------------------------> initialized
* loop_file_fmt_write_aio(...)
* initialized ------------------------------> initialized
* loop_file_fmt_discard(...)
* initialized ------------------------------> initialized
* loop_file_fmt_flush(...)
* initialized ------------------------------> initialized
* loop_file_fmt_sector_size(...)
* initialized ------------------------------> initialized
*
* loop_file_fmt_change(...)
* +-----------------------------------------------------------+
* | exit(...) init(...) |
* | initialized -------> uninitialized -------> initialized |
* +-----------------------------------------------------------+
*/
enum {
file_fmt_uninitialized = 0,
file_fmt_initialized
};
/**
* struct loop_file_fmt - Loop file format
*
* Data structure to use with the file format the loop file format subsystem.
*/
struct loop_file_fmt {
/**
* @file_fmt_type: Current type of the loop file format
*/
u32 file_fmt_type;
/**
* @file_fmt_state: Current state of the loop file format
*/
int file_fmt_state;
/**
* @lo: Link to a file format's loop device
*/
struct loop_device *lo;
/**
* @private_data: Optional link to a file format's driver specific data
*/
void *private_data;
};
/* subsystem functions for the driver implementation */
/**
* loop_file_fmt_register_driver - Register a loop file format driver
* @drv: File format driver
*
* Registers the specified loop file format driver @drv by the loop file format
* subsystem.
*/
extern int loop_file_fmt_register_driver(struct loop_file_fmt_driver *drv);
/**
* loop_file_fmt_unregister_driver - Unregister a loop file format driver
* @drv: File format driver
*
* Unregisters the specified loop file format driver @drv from the loop file
* format subsystem.
*/
extern void loop_file_fmt_unregister_driver(struct loop_file_fmt_driver *drv);
/* subsystem functions for subsystem usage */
/**
* loop_file_fmt_alloc - Allocate a loop file format
*
* Dynamically allocates a loop file format and returns a pointer to the
* created loop file format.
*/
extern struct loop_file_fmt *loop_file_fmt_alloc(void);
/**
* loop_file_fmt_free - Free an allocated loop file format
* @lo_fmt: Loop file format
*
* Frees the already allocated loop file format @lo_fmt.
*/
extern void loop_file_fmt_free(struct loop_file_fmt *lo_fmt);
/**
* loop_file_fmt_set_lo - Set the loop file format's loop device
* @lo_fmt: Loop file format
* @lo: Loop device
*
* The link to the loop device @lo is set in the loop file format @lo_fmt.
*/
extern int loop_file_fmt_set_lo(struct loop_file_fmt *lo_fmt,
struct loop_device *lo);
/**
* loop_file_fmt_get_lo - Get the loop file format's loop device
* @lo_fmt: Loop file format
*
* Returns a pointer to the loop device of the loop file format @lo_fmt.
*/
extern struct loop_device *loop_file_fmt_get_lo(struct loop_file_fmt *lo_fmt);
/**
* loop_file_fmt_init - Initialize a loop file format
* @lo_fmt: Loop file format
* @file_fmt_type: Type of the file format
*
* Initializes the specified loop file format @lo_fmt and sets up the correct
* file format type @file_fmt_type. Depending on @file_fmt_type, the correct
* loop file format driver is loaded in the subsystems backend. If no loop file
* format driver for the specified file format is available an error is
* returned.
*/
extern int loop_file_fmt_init(struct loop_file_fmt *lo_fmt,
u32 file_fmt_type);
/**
* loop_file_fmt_exit - Release a loop file format
* @lo_fmt: Loop file format
*
* Releases the specified loop file format @lo_fmt and all its resources.
*/
extern void loop_file_fmt_exit(struct loop_file_fmt *lo_fmt);
/**
* loop_file_fmt_read - Read IO from a loop file format
* @lo_fmt: Loop file format
* @rq: IO Request
*
* Reads IO from the file format's loop device by sending the IO read request
* @rq to the loop file format subsystem. The subsystem calls the registered
* callback function of the suitable loop file format driver.
*/
extern int loop_file_fmt_read(struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* loop_file_fmt_read_aio - Read IO from a loop file format asynchronously
* @lo_fmt: Loop file format
* @rq: IO Request
*
* Reads IO from the file format's loop device asynchronously by sending the
* IO read aio request @rq to the loop file format subsystem. The subsystem
* calls the registered callback function of the suitable loop file format
* driver.
*/
extern int loop_file_fmt_read_aio(struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* loop_file_fmt_write - Write IO to a loop file format
* @lo_fmt: Loop file format
* @rq: IO Request
*
* Write IO to the file format's loop device by sending the IO write request
* @rq to the loop file format subsystem. The subsystem calls the registered
* callback function of the suitable loop file format driver.
*/
extern int loop_file_fmt_write(struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* loop_file_fmt_write_aio - Write IO to a loop file format asynchronously
* @lo_fmt: Loop file format
* @rq: IO Request
*
* Write IO to the file format's loop device asynchronously by sending the
* IO write aio request @rq to the loop file format subsystem. The subsystem
* calls the registered callback function of the suitable loop file format
* driver.
*/
extern int loop_file_fmt_write_aio(struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* loop_file_fmt_discard - Discard IO on a loop file format
* @lo_fmt: Loop file format
* @rq: IO Request
*
* Discard IO on the file format's loop device by sending the IO discard
* request @rq to the loop file format subsystem. The subsystem calls the
* registered callback function of the suitable loop file format driver.
*/
extern int loop_file_fmt_discard(struct loop_file_fmt *lo_fmt,
struct request *rq);
/**
* loop_file_fmt_flush - Flush a loop file format
* @lo_fmt: Loop file format
*
* Flush the file format's loop device by calling the registered callback
* function of the suitable loop file format driver.
*/
extern int loop_file_fmt_flush(struct loop_file_fmt *lo_fmt);
/**
* loop_file_fmt_sector_size - Get sector size of a loop file format
* @lo_fmt: Loop file format
*
* Returns the physical sector size of the loop file format's loop device.
* If the loop file format implements a sparse disk image format, then this
* function returns the virtual sector size.
*/
extern loff_t loop_file_fmt_sector_size(struct loop_file_fmt *lo_fmt);
/**
* loop_file_fmt_change - Change the loop file format's type
* @lo_fmt: Loop file format
* @file_fmt_type_new: Loop file format type
*
* Changes the file format type of the already initialized loop file format
* @lo_fmt. Therefore, the function releases the old file format and frees all
* of its resources before the loop file format @lo_fmt is initialized and set
* up with the new file format @file_fmt_type_new.
*/
extern int loop_file_fmt_change(struct loop_file_fmt *lo_fmt,
u32 file_fmt_type_new);
/* helper functions of the subsystem */
/**
* loop_file_fmt_print_type - Convert file format type to string
* @file_fmt_type: Loop file format type
* @file_fmt_name: Loop file format type string
*
* Converts the specified numeric @file_fmt_type value into a human readable
* string stating the file format as string in @file_fmt_name.
*/
extern ssize_t loop_file_fmt_print_type(u32 file_fmt_type,
char *file_fmt_name);
#endif
