/*
 * 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 dm_report_zones_args;
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_DAX_BIO_BASED    = 3,
        DM_TYPE_NVME_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,
                                             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, blk_status_t *error);
typedef int (*dm_request_endio_fn) (struct dm_target *ti,
                                    struct request *clone, blk_status_t 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,
                              char *result, unsigned maxlen);

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

typedef int (*dm_report_zones_fn) (struct dm_target *ti,
                                   struct dm_report_zones_args *args,
                                   unsigned int nr_zones);

/*
 * 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);
typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i);
#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;
#if 1 /* CONFIG_BLK_DEV_ZONED */
        dm_report_zones_fn report_zones;
#endif
        dm_busy_fn busy;
        dm_iterate_devices_fn iterate_devices;
        dm_io_hints_fn io_hints;
        dm_dax_direct_access_fn direct_access;
        dm_dax_copy_iter_fn dax_copy_from_iter;
        dm_dax_copy_iter_fn dax_copy_to_iter;

        /* 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)

/*
 * 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)

/*
 * Indicates that a target supports host-managed zoned block devices.
 */
#define DM_TARGET_ZONED_HM              0x00000040
#define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)

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 secure erase bios that will be submitted to the target.
         * The bio number can be accessed with dm_bio_get_target_bio_nr.
         */
        unsigned num_secure_erase_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;

        /* 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);
};

void *dm_per_bio_data(struct bio *bio, size_t data_size);
struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size);
unsigned dm_bio_get_target_bio_nr(const struct bio *bio);

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(const 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(const 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_post_suspending(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);

#ifdef CONFIG_BLK_DEV_ZONED
struct dm_report_zones_args {
        struct dm_target *tgt;
        sector_t next_sector;

        void *orig_data;
        report_zones_cb orig_cb;
        unsigned int zone_idx;

        /* must be filled by ->report_zones before calling dm_report_zones_cb */
        sector_t start;
};
int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx, void *data);
#endif /* CONFIG_BLK_DEV_ZONED */

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);

/*
 * Destroy the table when finished.
 */
void dm_table_destroy(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);
const char *dm_table_device_name(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"

#define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"

#define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)

#define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
#define DMERR_LIMIT(fmt, ...) pr_err_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
#define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
#define DMWARN_LIMIT(fmt, ...) pr_warn_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
#define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
#define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)

#define DMDEBUG(fmt, ...) pr_debug(DM_FMT(fmt), ##__VA_ARGS__)
#define DMDEBUG_LIMIT(fmt, ...) pr_debug_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)

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

/*
 * Definitions of return values from target end_io function.
 */
#define DM_ENDIO_DONE           0
#define DM_ENDIO_INCOMPLETE     1
#define DM_ENDIO_REQUEUE        2
#define DM_ENDIO_DELAY_REQUEUE  3

/*
 * 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  DM_ENDIO_DELAY_REQUEUE
#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))

/*
 * 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);
}

#endif  /* _LINUX_DEVICE_MAPPER_H */