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Diffstat (limited to 'loop_file_fmt.h')
| -rw-r--r-- | loop_file_fmt.h | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/loop_file_fmt.h b/loop_file_fmt.h new file mode 100644 index 0000000..5c0e493 --- /dev/null +++ b/loop_file_fmt.h @@ -0,0 +1,351 @@ +/* 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 |