/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright 2023 Red Hat
 */

#ifndef VDO_PHYSICAL_ZONE_H
#define VDO_PHYSICAL_ZONE_H

#include <linux/atomic.h>

#include "types.h"

/*
 * The type of a PBN lock.
 */
enum pbn_lock_type {
        VIO_READ_LOCK,
        VIO_WRITE_LOCK,
        VIO_BLOCK_MAP_WRITE_LOCK,
};

struct pbn_lock_implementation;

/*
 * A PBN lock.
 */
struct pbn_lock {
        /* The implementation of the lock */
        const struct pbn_lock_implementation *implementation;

        /* The number of VIOs holding or sharing this lock */
        data_vio_count_t holder_count;
        /*
         * The number of compressed block writers holding a share of this lock while they are
         * acquiring a reference to the PBN.
         */
        u8 fragment_locks;

        /* Whether the locked PBN has been provisionally referenced on behalf of the lock holder. */
        bool has_provisional_reference;

        /*
         * For read locks, the number of references that were known to be available on the locked
         * block at the time the lock was acquired.
         */
        u8 increment_limit;

        /*
         * For read locks, the number of data_vios that have tried to claim one of the available
         * increments during the lifetime of the lock. Each claim will first increment this
         * counter, so it can exceed the increment limit.
         */
        atomic_t increments_claimed;
};

struct physical_zone {
        /* Which physical zone this is */
        zone_count_t zone_number;
        /* The thread ID for this zone */
        thread_id_t thread_id;
        /* In progress operations keyed by PBN */
        struct int_map *pbn_operations;
        /* Pool of unused pbn_lock instances */
        struct pbn_lock_pool *lock_pool;
        /* The block allocator for this zone */
        struct block_allocator *allocator;
        /* The next zone from which to attempt an allocation */
        struct physical_zone *next;
};

struct physical_zones {
        /* The number of zones */
        zone_count_t zone_count;
        /* The physical zones themselves */
        struct physical_zone zones[];
};

bool __must_check vdo_is_pbn_read_lock(const struct pbn_lock *lock);
void vdo_downgrade_pbn_write_lock(struct pbn_lock *lock, bool compressed_write);
bool __must_check vdo_claim_pbn_lock_increment(struct pbn_lock *lock);

/**
 * vdo_pbn_lock_has_provisional_reference() - Check whether a PBN lock has a provisional reference.
 * @lock: The PBN lock.
 */
static inline bool vdo_pbn_lock_has_provisional_reference(struct pbn_lock *lock)
{
        return ((lock != NULL) && lock->has_provisional_reference);
}

void vdo_assign_pbn_lock_provisional_reference(struct pbn_lock *lock);
void vdo_unassign_pbn_lock_provisional_reference(struct pbn_lock *lock);

int __must_check vdo_make_physical_zones(struct vdo *vdo,
                                         struct physical_zones **zones_ptr);

void vdo_free_physical_zones(struct physical_zones *zones);

struct pbn_lock * __must_check vdo_get_physical_zone_pbn_lock(struct physical_zone *zone,
                                                              physical_block_number_t pbn);

int __must_check vdo_attempt_physical_zone_pbn_lock(struct physical_zone *zone,
                                                    physical_block_number_t pbn,
                                                    enum pbn_lock_type type,
                                                    struct pbn_lock **lock_ptr);

bool __must_check vdo_allocate_block_in_zone(struct data_vio *data_vio);

void vdo_release_physical_zone_pbn_lock(struct physical_zone *zone,
                                        physical_block_number_t locked_pbn,
                                        struct pbn_lock *lock);

void vdo_dump_physical_zone(const struct physical_zone *zone);

#endif /* VDO_PHYSICAL_ZONE_H */