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Release 4.12 include/linux/device-mapper.h

Directory: include/linux
/*
 * Copyright (C) 2001 Sistina Software (UK) Limited.
 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the LGPL.
 */

#ifndef _LINUX_DEVICE_MAPPER_H

#define _LINUX_DEVICE_MAPPER_H

#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/math64.h>
#include <linux/ratelimit.h>

struct dm_dev;
struct dm_target;
struct dm_table;
struct mapped_device;
struct bio_vec;

/*
 * Type of table, mapped_device's mempool and request_queue
 */

enum dm_queue_mode {
	
DM_TYPE_NONE		 = 0,
	
DM_TYPE_BIO_BASED	 = 1,
	
DM_TYPE_REQUEST_BASED	 = 2,
	
DM_TYPE_MQ_REQUEST_BASED = 3,
	
DM_TYPE_DAX_BIO_BASED	 = 4,
};




typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;


union map_info {
	
void *ptr;
};

/*
 * In the constructor the target parameter will already have the
 * table, type, begin and len fields filled in.
 */

typedef int (*dm_ctr_fn) (struct dm_target *target,
			  unsigned int argc, char **argv);

/*
 * The destructor doesn't need to free the dm_target, just
 * anything hidden ti->private.
 */

typedef void (*dm_dtr_fn) (struct dm_target *ti);

/*
 * The map function must return:
 * < 0: error
 * = 0: The target will handle the io by resubmitting it later
 * = 1: simple remap complete
 * = 2: The target wants to push back the io
 */

typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);

typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
					    struct request *rq,
					    union map_info *map_context,
					    struct request **clone);

typedef void (*dm_release_clone_request_fn) (struct request *clone);

/*
 * Returns:
 * < 0 : error (currently ignored)
 * 0   : ended successfully
 * 1   : for some reason the io has still not completed (eg,
 *       multipath target might want to requeue a failed io).
 * 2   : The target wants to push back the io
 */

typedef int (*dm_endio_fn) (struct dm_target *ti,
			    struct bio *bio, int error);

typedef int (*dm_request_endio_fn) (struct dm_target *ti,
				    struct request *clone, int error,
				    union map_info *map_context);


typedef void (*dm_presuspend_fn) (struct dm_target *ti);

typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);

typedef void (*dm_postsuspend_fn) (struct dm_target *ti);

typedef int (*dm_preresume_fn) (struct dm_target *ti);

typedef void (*dm_resume_fn) (struct dm_target *ti);


typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
			      unsigned status_flags, char *result, unsigned maxlen);


typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);


typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
			    struct block_device **bdev, fmode_t *mode);

/*
 * These iteration functions are typically used to check (and combine)
 * properties of underlying devices.
 * E.g. Does at least one underlying device support flush?
 *      Does any underlying device not support WRITE_SAME?
 *
 * The callout function is called once for each contiguous section of
 * an underlying device.  State can be maintained in *data.
 * Return non-zero to stop iterating through any further devices.
 */

typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
					   struct dm_dev *dev,
					   sector_t start, sector_t len,
					   void *data);

/*
 * This function must iterate through each section of device used by the
 * target until it encounters a non-zero return code, which it then returns.
 * Returns zero if no callout returned non-zero.
 */

typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
				      iterate_devices_callout_fn fn,
				      void *data);


typedef void (*dm_io_hints_fn) (struct dm_target *ti,
				struct queue_limits *limits);

/*
 * Returns:
 *    0: The target can handle the next I/O immediately.
 *    1: The target can't handle the next I/O immediately.
 */

typedef int (*dm_busy_fn) (struct dm_target *ti);

/*
 * Returns:
 *  < 0 : error
 * >= 0 : the number of bytes accessible at the address
 */

typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
		long nr_pages, void **kaddr, pfn_t *pfn);

#define PAGE_SECTORS (PAGE_SIZE / 512)

void dm_error(const char *message);


struct dm_dev {
	
struct block_device *bdev;
	
struct dax_device *dax_dev;
	
fmode_t mode;
	
char name[16];
};

dev_t dm_get_dev_t(const char *path);

/*
 * Constructors should call these functions to ensure destination devices
 * are opened/closed correctly.
 */
int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
		  struct dm_dev **result);
void dm_put_device(struct dm_target *ti, struct dm_dev *d);

/*
 * Information about a target type
 */


struct target_type {
	
uint64_t features;
	
const char *name;
	
struct module *module;
	
unsigned version[3];
	
dm_ctr_fn ctr;
	
dm_dtr_fn dtr;
	
dm_map_fn map;
	
dm_clone_and_map_request_fn clone_and_map_rq;
	
dm_release_clone_request_fn release_clone_rq;
	
dm_endio_fn end_io;
	
dm_request_endio_fn rq_end_io;
	
dm_presuspend_fn presuspend;
	
dm_presuspend_undo_fn presuspend_undo;
	
dm_postsuspend_fn postsuspend;
	
dm_preresume_fn preresume;
	
dm_resume_fn resume;
	
dm_status_fn status;
	
dm_message_fn message;
	
dm_prepare_ioctl_fn prepare_ioctl;
	
dm_busy_fn busy;
	
dm_iterate_devices_fn iterate_devices;
	
dm_io_hints_fn io_hints;
	
dm_dax_direct_access_fn direct_access;

	/* For internal device-mapper use. */
	
struct list_head list;
};

/*
 * Target features
 */

/*
 * Any table that contains an instance of this target must have only one.
 */

#define DM_TARGET_SINGLETON		0x00000001

#define dm_target_needs_singleton(type)	((type)->features & DM_TARGET_SINGLETON)

/*
 * Indicates that a target does not support read-only devices.
 */

#define DM_TARGET_ALWAYS_WRITEABLE	0x00000002

#define dm_target_always_writeable(type) \
		((type)->features & DM_TARGET_ALWAYS_WRITEABLE)

/*
 * Any device that contains a table with an instance of this target may never
 * have tables containing any different target type.
 */

#define DM_TARGET_IMMUTABLE		0x00000004

#define dm_target_is_immutable(type)	((type)->features & DM_TARGET_IMMUTABLE)

/*
 * Indicates that a target may replace any target; even immutable targets.
 * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
 */

#define DM_TARGET_WILDCARD		0x00000008

#define dm_target_is_wildcard(type)	((type)->features & DM_TARGET_WILDCARD)

/*
 * Some targets need to be sent the same WRITE bio severals times so
 * that they can send copies of it to different devices.  This function
 * examines any supplied bio and returns the number of copies of it the
 * target requires.
 */

typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);

/*
 * A target implements own bio data integrity.
 */

#define DM_TARGET_INTEGRITY		0x00000010

#define dm_target_has_integrity(type)	((type)->features & DM_TARGET_INTEGRITY)

/*
 * A target passes integrity data to the lower device.
 */

#define DM_TARGET_PASSES_INTEGRITY	0x00000020

#define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)


struct dm_target {
	
struct dm_table *table;
	
struct target_type *type;

	/* target limits */
	
sector_t begin;
	
sector_t len;

	/* If non-zero, maximum size of I/O submitted to a target. */
	
uint32_t max_io_len;

	/*
         * A number of zero-length barrier bios that will be submitted
         * to the target for the purpose of flushing cache.
         *
         * The bio number can be accessed with dm_bio_get_target_bio_nr.
         * It is a responsibility of the target driver to remap these bios
         * to the real underlying devices.
         */
	
unsigned num_flush_bios;

	/*
         * The number of discard bios that will be submitted to the target.
         * The bio number can be accessed with dm_bio_get_target_bio_nr.
         */
	
unsigned num_discard_bios;

	/*
         * The number of WRITE SAME bios that will be submitted to the target.
         * The bio number can be accessed with dm_bio_get_target_bio_nr.
         */
	
unsigned num_write_same_bios;

	/*
         * The number of WRITE ZEROES bios that will be submitted to the target.
         * The bio number can be accessed with dm_bio_get_target_bio_nr.
         */
	
unsigned num_write_zeroes_bios;

	/*
         * The minimum number of extra bytes allocated in each io for the
         * target to use.
         */
	
unsigned per_io_data_size;

	/*
         * If defined, this function is called to find out how many
         * duplicate bios should be sent to the target when writing
         * data.
         */
	
dm_num_write_bios_fn num_write_bios;

	/* target specific data */
	
void *private;

	/* Used to provide an error string from the ctr */
	
char *error;

	/*
         * Set if this target needs to receive flushes regardless of
         * whether or not its underlying devices have support.
         */
	
bool flush_supported:1;

	/*
         * Set if this target needs to receive discards regardless of
         * whether or not its underlying devices have support.
         */
	
bool discards_supported:1;

	/*
         * Set if the target required discard bios to be split
         * on max_io_len boundary.
         */
	
bool split_discard_bios:1;
};

/* Each target can link one of these into the table */

struct dm_target_callbacks {
	
struct list_head list;
	
int (*congested_fn) (struct dm_target_callbacks *, int);
};

/*
 * For bio-based dm.
 * One of these is allocated for each bio.
 * This structure shouldn't be touched directly by target drivers.
 * It is here so that we can inline dm_per_bio_data and
 * dm_bio_from_per_bio_data
 */

struct dm_target_io {
	
struct dm_io *io;
	
struct dm_target *ti;
	
unsigned target_bio_nr;
	
unsigned *len_ptr;
	
struct bio clone;
};




static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
{
	return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
}


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Total33100.00%1100.00%






static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
{
	return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
}


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static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
{
	return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
}


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Mikulas Patocka2492.31%150.00%


Alasdair G. Kergon27.69%150.00%


Total26100.00%2100.00%



int dm_register_target(struct target_type *t);
void dm_unregister_target(struct target_type *t);

/*
 * Target argument parsing.
 */

struct dm_arg_set {
	
unsigned argc;
	
char **argv;
};

/*
 * The minimum and maximum value of a numeric argument, together with
 * the error message to use if the number is found to be outside that range.
 */

struct dm_arg {
	
unsigned min;
	
unsigned max;
	
char *error;
};

/*
 * Validate the next argument, either returning it as *value or, if invalid,
 * returning -EINVAL and setting *error.
 */
int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
		unsigned *value, char **error);

/*
 * Process the next argument as the start of a group containing between
 * arg->min and arg->max further arguments. Either return the size as
 * *num_args or, if invalid, return -EINVAL and set *error.
 */
int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
		      unsigned *num_args, char **error);

/*
 * Return the current argument and shift to the next.
 */
const char *dm_shift_arg(struct dm_arg_set *as);

/*
 * Move through num_args arguments.
 */
void dm_consume_args(struct dm_arg_set *as, unsigned num_args);

/*-----------------------------------------------------------------
 * Functions for creating and manipulating mapped devices.
 * Drop the reference with dm_put when you finish with the object.
 *---------------------------------------------------------------*/

/*
 * DM_ANY_MINOR chooses the next available minor number.
 */

#define DM_ANY_MINOR (-1)
int dm_create(int minor, struct mapped_device **md);

/*
 * Reference counting for md.
 */
struct mapped_device *dm_get_md(dev_t dev);
void dm_get(struct mapped_device *md);
int dm_hold(struct mapped_device *md);
void dm_put(struct mapped_device *md);

/*
 * An arbitrary pointer may be stored alongside a mapped device.
 */
void dm_set_mdptr(struct mapped_device *md, void *ptr);
void *dm_get_mdptr(struct mapped_device *md);

/*
 * A device can still be used while suspended, but I/O is deferred.
 */
int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
int dm_resume(struct mapped_device *md);

/*
 * Event functions.
 */
uint32_t dm_get_event_nr(struct mapped_device *md);
int dm_wait_event(struct mapped_device *md, int event_nr);
uint32_t dm_next_uevent_seq(struct mapped_device *md);
void dm_uevent_add(struct mapped_device *md, struct list_head *elist);

/*
 * Info functions.
 */
const char *dm_device_name(struct mapped_device *md);
int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
struct gendisk *dm_disk(struct mapped_device *md);
int dm_suspended(struct dm_target *ti);
int dm_noflush_suspending(struct dm_target *ti);
void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
union map_info *dm_get_rq_mapinfo(struct request *rq);

struct queue_limits *dm_get_queue_limits(struct mapped_device *md);

/*
 * Geometry functions.
 */
int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);

/*-----------------------------------------------------------------
 * Functions for manipulating device-mapper tables.
 *---------------------------------------------------------------*/

/*
 * First create an empty table.
 */
int dm_table_create(struct dm_table **result, fmode_t mode,
		    unsigned num_targets, struct mapped_device *md);

/*
 * Then call this once for each target.
 */
int dm_table_add_target(struct dm_table *t, const char *type,
			sector_t start, sector_t len, char *params);

/*
 * Target_ctr should call this if it needs to add any callbacks.
 */
void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);

/*
 * Target can use this to set the table's type.
 * Can only ever be called from a target's ctr.
 * Useful for "hybrid" target (supports both bio-based
 * and request-based).
 */
void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type);

/*
 * Finally call this to make the table ready for use.
 */
int dm_table_complete(struct dm_table *t);

/*
 * Target may require that it is never sent I/O larger than len.
 */
int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);

/*
 * Table reference counting.
 */
struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
void dm_put_live_table(struct mapped_device *md, int srcu_idx);
void dm_sync_table(struct mapped_device *md);

/*
 * Queries
 */
sector_t dm_table_get_size(struct dm_table *t);
unsigned int dm_table_get_num_targets(struct dm_table *t);
fmode_t dm_table_get_mode(struct dm_table *t);
struct mapped_device *dm_table_get_md(struct dm_table *t);

/*
 * Trigger an event.
 */
void dm_table_event(struct dm_table *t);

/*
 * Run the queue for request-based targets.
 */
void dm_table_run_md_queue_async(struct dm_table *t);

/*
 * The device must be suspended before calling this method.
 * Returns the previous table, which the caller must destroy.
 */
struct dm_table *dm_swap_table(struct mapped_device *md,
			       struct dm_table *t);

/*
 * A wrapper around vmalloc.
 */
void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);

/*-----------------------------------------------------------------
 * Macros.
 *---------------------------------------------------------------*/

#define DM_NAME "device-mapper"

#ifdef CONFIG_PRINTK
extern struct ratelimit_state dm_ratelimit_state;


#define dm_ratelimit()	__ratelimit(&dm_ratelimit_state)
#else

#define dm_ratelimit()	0
#endif


#define DMCRIT(f, arg...) \
	printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)


#define DMERR(f, arg...) \
	printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)

#define DMERR_LIMIT(f, arg...) \
	do { \
                if (dm_ratelimit())     \
                        printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
                               f "\n", ## arg); \
        } while (0)


#define DMWARN(f, arg...) \
	printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)

#define DMWARN_LIMIT(f, arg...) \
	do { \
                if (dm_ratelimit())     \
                        printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
                               f "\n", ## arg); \
        } while (0)


#define DMINFO(f, arg...) \
	printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)

#define DMINFO_LIMIT(f, arg...) \
	do { \
                if (dm_ratelimit())     \
                        printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
                               "\n", ## arg); \
        } while (0)

#ifdef CONFIG_DM_DEBUG

#  define DMDEBUG(f, arg...) \
	printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)

#  define DMDEBUG_LIMIT(f, arg...) \
	do { \
                if (dm_ratelimit())     \
                        printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
                               "\n", ## arg); \
        } while (0)
#else

#  define DMDEBUG(f, arg...) do {} while (0)

#  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
#endif


#define DMEMIT(x...) sz += ((sz >= maxlen) ? \
                          0 : scnprintf(result + sz, maxlen - sz, x))


#define SECTOR_SHIFT 9

/*
 * Definitions of return values from target end_io function.
 */

#define DM_ENDIO_DONE		0

#define DM_ENDIO_INCOMPLETE	1

#define DM_ENDIO_REQUEUE	2

/*
 * Definitions of return values from target map function.
 */

#define DM_MAPIO_SUBMITTED	0

#define DM_MAPIO_REMAPPED	1

#define DM_MAPIO_REQUEUE	DM_ENDIO_REQUEUE

#define DM_MAPIO_DELAY_REQUEUE	3

#define DM_MAPIO_KILL		4


#define dm_sector_div64(x, y)( \
{ \
        u64 _res; \
        (x) = div64_u64_rem(x, y, &_res); \
        _res; \
} \
)

/*
 * Ceiling(n / sz)
 */

#define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))


#define dm_sector_div_up(n, sz) ( \
{ \
        sector_t _r = ((n) + (sz) - 1); \
        sector_div(_r, (sz)); \
        _r; \
} \
)

/*
 * ceiling(n / size) * size
 */

#define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))


#define dm_array_too_big(fixed, obj, num) \
	((num) > (UINT_MAX - (fixed)) / (obj))

/*
 * Sector offset taken relative to the start of the target instead of
 * relative to the start of the device.
 */

#define dm_target_offset(ti, sector) ((sector) - (ti)->begin)




static inline sector_t to_sector(unsigned long n)
{
	return (n >> SECTOR_SHIFT);
}


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Alasdair G. Kergon18100.00%1100.00%


Total18100.00%1100.00%






static inline unsigned long to_bytes(sector_t n)
{
	return (n << SECTOR_SHIFT);
}


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Alasdair G. Kergon18100.00%1100.00%


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#endif	/* _LINUX_DEVICE_MAPPER_H */

Overall Contributors
PersonTokensPropCommitsCommitProp
Alasdair G. Kergon65534.91%1518.75%


Mike Snitzer33417.80%1721.25%


Mikulas Patocka24813.22%1518.75%


Alan Cox22111.78%11.25%


Kiyoshi Ueda754.00%56.25%


Milan Broz492.61%45.00%


Mike Anderson402.13%22.50%


Andrew Morton392.08%22.50%


Neil Brown382.03%11.25%


Joe Thornber371.97%33.75%


Namhyung Kim291.55%11.25%


Toshi Kani261.39%11.25%


Christoph Hellwig231.23%45.00%


Bart Van Assche211.12%11.25%


Dan J Williams160.85%22.50%


DingXiang90.48%11.25%


Cheng Renquan50.27%11.25%


Al Viro40.21%11.25%


Andi Kleen30.16%11.25%


Heinz Mauelshagen30.16%11.25%


Nikanth Karthikesan10.05%11.25%


Total1876100.00%80100.00%


Directory: include/linux



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