/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#ifndef _LINUX_DM_SPACE_MAP_H
#define _LINUX_DM_SPACE_MAP_H

#include "dm-block-manager.h"

typedef void (*dm_sm_threshold_fn)(void *context);

/*
 * struct dm_space_map keeps a record of how many times each block in a device
 * is referenced.  It needs to be fixed on disk as part of the transaction.
 */
struct dm_space_map {
        void (*destroy)(struct dm_space_map *sm);

        /*
         * You must commit before allocating the newly added space.
         */
        int (*extend)(struct dm_space_map *sm, dm_block_t extra_blocks);

        /*
         * Extensions do not appear in this count until after commit has
         * been called.
         */
        int (*get_nr_blocks)(struct dm_space_map *sm, dm_block_t *count);

        /*
         * Space maps must never allocate a block from the previous
         * transaction, in case we need to rollback.  This complicates the
         * semantics of get_nr_free(), it should return the number of blocks
         * that are available for allocation _now_.  For instance you may
         * have blocks with a zero reference count that will not be
         * available for allocation until after the next commit.
         */
        int (*get_nr_free)(struct dm_space_map *sm, dm_block_t *count);

        int (*get_count)(struct dm_space_map *sm, dm_block_t b, uint32_t *result);
        int (*count_is_more_than_one)(struct dm_space_map *sm, dm_block_t b,
                                      int *result);
        int (*set_count)(struct dm_space_map *sm, dm_block_t b, uint32_t count);

        int (*commit)(struct dm_space_map *sm);

        int (*inc_blocks)(struct dm_space_map *sm, dm_block_t b, dm_block_t e);
        int (*dec_blocks)(struct dm_space_map *sm, dm_block_t b, dm_block_t e);

        /*
         * new_block will increment the returned block.
         */
        int (*new_block)(struct dm_space_map *sm, dm_block_t *b);

        /*
         * The root contains all the information needed to fix the space map.
         * Generally this info is small, so squirrel it away in a disk block
         * along with other info.
         */
        int (*root_size)(struct dm_space_map *sm, size_t *result);
        int (*copy_root)(struct dm_space_map *sm, void *copy_to_here_le, size_t len);

        /*
         * You can register one threshold callback which is edge-triggered
         * when the free space in the space map drops below the threshold.
         */
        int (*register_threshold_callback)(struct dm_space_map *sm,
                                           dm_block_t threshold,
                                           dm_sm_threshold_fn fn,
                                           void *context);
};

/*----------------------------------------------------------------*/

static inline void dm_sm_destroy(struct dm_space_map *sm)
{
        if (sm)
                sm->destroy(sm);
}

static inline int dm_sm_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
        return sm->extend(sm, extra_blocks);
}

static inline int dm_sm_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
        return sm->get_nr_blocks(sm, count);
}

static inline int dm_sm_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
        return sm->get_nr_free(sm, count);
}

static inline int dm_sm_get_count(struct dm_space_map *sm, dm_block_t b,
                                  uint32_t *result)
{
        return sm->get_count(sm, b, result);
}

static inline int dm_sm_count_is_more_than_one(struct dm_space_map *sm,
                                               dm_block_t b, int *result)
{
        return sm->count_is_more_than_one(sm, b, result);
}

static inline int dm_sm_set_count(struct dm_space_map *sm, dm_block_t b,
                                  uint32_t count)
{
        return sm->set_count(sm, b, count);
}

static inline int dm_sm_commit(struct dm_space_map *sm)
{
        return sm->commit(sm);
}

static inline int dm_sm_inc_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e)
{
        return sm->inc_blocks(sm, b, e);
}

static inline int dm_sm_inc_block(struct dm_space_map *sm, dm_block_t b)
{
        return dm_sm_inc_blocks(sm, b, b + 1);
}

static inline int dm_sm_dec_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e)
{
        return sm->dec_blocks(sm, b, e);
}

static inline int dm_sm_dec_block(struct dm_space_map *sm, dm_block_t b)
{
        return dm_sm_dec_blocks(sm, b, b + 1);
}

static inline int dm_sm_new_block(struct dm_space_map *sm, dm_block_t *b)
{
        return sm->new_block(sm, b);
}

static inline int dm_sm_root_size(struct dm_space_map *sm, size_t *result)
{
        return sm->root_size(sm, result);
}

static inline int dm_sm_copy_root(struct dm_space_map *sm, void *copy_to_here_le, size_t len)
{
        return sm->copy_root(sm, copy_to_here_le, len);
}

static inline int dm_sm_register_threshold_callback(struct dm_space_map *sm,
                                                    dm_block_t threshold,
                                                    dm_sm_threshold_fn fn,
                                                    void *context)
{
        if (sm->register_threshold_callback)
                return sm->register_threshold_callback(sm, threshold, fn, context);

        return -EINVAL;
}


#endif  /* _LINUX_DM_SPACE_MAP_H */