/*
   * 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;
  
  typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  
  union map_info {
  	void *ptr;
  	unsigned long long ll;
  };
  
  /*
   * 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_map_request_fn) (struct dm_target *ti, struct request *clone,
  				  union map_info *map_context);
  
  /*
   * 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_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_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  			    unsigned long arg);
  
  typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  			    struct bio_vec *biovec, int max_size);
  
  /*
   * 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);
  
  void dm_error(const char *message);
  
  /*
   * Combine device limits.
   */
  int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
  			 sector_t start, sector_t len, void *data);
  
  struct dm_dev {
  	struct block_device *bdev;
  	fmode_t mode;
  	char name[16];
  };
  
  /*
   * 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_map_request_fn map_rq;
  	dm_endio_fn end_io;
  	dm_request_endio_fn rq_end_io;
  	dm_presuspend_fn presuspend;
  	dm_postsuspend_fn postsuspend;
  	dm_preresume_fn preresume;
  	dm_resume_fn resume;
  	dm_status_fn status;
  	dm_message_fn message;
  	dm_ioctl_fn ioctl;
  	dm_merge_fn merge;
  	dm_busy_fn busy;
  	dm_iterate_devices_fn iterate_devices;
  	dm_io_hints_fn io_hints;
  
  	/* 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)
  
  /*
   * 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);
  
  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 minimum number of extra bytes allocated in each bio for the
  	 * target to use.  dm_per_bio_data returns the data location.
  	 */
  	unsigned per_bio_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;
  
  	/*
  	 * Set if this target does not return zeroes on discarded blocks.
  	 */
  	bool discard_zeroes_data_unsupported: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;
  	union map_info info;
  	unsigned target_bio_nr;
  	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;
  }
  
  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));
  }
  
  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;
  }
  
  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);
  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);
  union map_info *dm_get_mapinfo(struct bio *bio);
  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);
  
  /*
   * 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);
  
  /*
   * 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 "
  ", ## arg)
  
  #define DMERR(f, arg...) \
  	printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "
  ", ## arg)
  #define DMERR_LIMIT(f, arg...) \
  	do { \
  		if (dm_ratelimit())	\
  			printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
  			       f "
  ", ## arg); \
  	} while (0)
  
  #define DMWARN(f, arg...) \
  	printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "
  ", ## arg)
  #define DMWARN_LIMIT(f, arg...) \
  	do { \
  		if (dm_ratelimit())	\
  			printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
  			       f "
  ", ## arg); \
  	} while (0)
  
  #define DMINFO(f, arg...) \
  	printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "
  ", ## arg)
  #define DMINFO_LIMIT(f, arg...) \
  	do { \
  		if (dm_ratelimit())	\
  			printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
  			       "
  ", ## arg); \
  	} while (0)
  
  #ifdef CONFIG_DM_DEBUG
  #  define DMDEBUG(f, arg...) \
  	printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "
  ", ## arg)
  #  define DMDEBUG_LIMIT(f, arg...) \
  	do { \
  		if (dm_ratelimit())	\
  			printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
  			       "
  ", ## 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_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_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);
  }
  
  static inline unsigned long to_bytes(sector_t n)
  {
  	return (n << SECTOR_SHIFT);
  }
  
  /*-----------------------------------------------------------------
   * Helper for block layer and dm core operations
   *---------------------------------------------------------------*/
  void dm_dispatch_request(struct request *rq);
  void dm_requeue_unmapped_request(struct request *rq);
  void dm_kill_unmapped_request(struct request *rq, int error);
  int dm_underlying_device_busy(struct request_queue *q);
  
  #endif	/* _LINUX_DEVICE_MAPPER_H */