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

#include "logical-zone.h"

#include "logger.h"
#include "memory-alloc.h"
#include "permassert.h"
#include "string-utils.h"

#include "action-manager.h"
#include "admin-state.h"
#include "block-map.h"
#include "completion.h"
#include "constants.h"
#include "data-vio.h"
#include "flush.h"
#include "int-map.h"
#include "physical-zone.h"
#include "vdo.h"

#define ALLOCATIONS_PER_ZONE 128

/**
 * as_logical_zone() - Convert a generic vdo_completion to a logical_zone.
 * @completion: The completion to convert.
 *
 * Return: The completion as a logical_zone.
 */
static struct logical_zone *as_logical_zone(struct vdo_completion *completion)
{
	vdo_assert_completion_type(completion, VDO_GENERATION_FLUSHED_COMPLETION);
	return container_of(completion, struct logical_zone, completion);
}

/* get_thread_id_for_zone() - Implements vdo_zone_thread_getter_fn. */
static thread_id_t get_thread_id_for_zone(void *context, zone_count_t zone_number)
{
	struct logical_zones *zones = context;

	return zones->zones[zone_number].thread_id;
}

/**
 * initialize_zone() - Initialize a logical zone.
 * @zones: The logical_zones to which this zone belongs.
 * @zone_number: The logical_zone's index.
 */
static int initialize_zone(struct logical_zones *zones, zone_count_t zone_number)
{
	int result;
	struct vdo *vdo = zones->vdo;
	struct logical_zone *zone = &zones->zones[zone_number];
	zone_count_t allocation_zone_number;

	result = vdo_int_map_create(VDO_LOCK_MAP_CAPACITY, &zone->lbn_operations);
	if (result != VDO_SUCCESS)
		return result;

	if (zone_number < vdo->thread_config.logical_zone_count - 1)
		zone->next = &zones->zones[zone_number + 1];

	vdo_initialize_completion(&zone->completion, vdo,
				  VDO_GENERATION_FLUSHED_COMPLETION);
	zone->zones = zones;
	zone->zone_number = zone_number;
	zone->thread_id = vdo->thread_config.logical_threads[zone_number];
	zone->block_map_zone = &vdo->block_map->zones[zone_number];
	INIT_LIST_HEAD(&zone->write_vios);
	vdo_set_admin_state_code(&zone->state, VDO_ADMIN_STATE_NORMAL_OPERATION);

	allocation_zone_number = zone->thread_id % vdo->thread_config.physical_zone_count;
	zone->allocation_zone = &vdo->physical_zones->zones[allocation_zone_number];

	return vdo_make_default_thread(vdo, zone->thread_id);
}

/**
 * vdo_make_logical_zones() - Create a set of logical zones.
 * @vdo: The vdo to which the zones will belong.
 * @zones_ptr: A pointer to hold the new zones.
 *
 * Return: VDO_SUCCESS or an error code.
 */
int vdo_make_logical_zones(struct vdo *vdo, struct logical_zones **zones_ptr)
{
	struct logical_zones *zones;
	int result;
	zone_count_t zone;
	zone_count_t zone_count = vdo->thread_config.logical_zone_count;

	if (zone_count == 0)
		return VDO_SUCCESS;

	result = vdo_allocate_extended(struct logical_zones, zone_count,
				       struct logical_zone, __func__, &zones);
	if (result != VDO_SUCCESS)
		return result;

	zones->vdo = vdo;
	zones->zone_count = zone_count;
	for (zone = 0; zone < zone_count; zone++) {
		result = initialize_zone(zones, zone);
		if (result != VDO_SUCCESS) {
			vdo_free_logical_zones(zones);
			return result;
		}
	}

	result = vdo_make_action_manager(zones->zone_count, get_thread_id_for_zone,
					 vdo->thread_config.admin_thread, zones, NULL,
					 vdo, &zones->manager);
	if (result != VDO_SUCCESS) {
		vdo_free_logical_zones(zones);
		return result;
	}

	*zones_ptr = zones;
	return VDO_SUCCESS;
}

/**
 * vdo_free_logical_zones() - Free a set of logical zones.
 * @zones: The set of zones to free.
 */
void vdo_free_logical_zones(struct logical_zones *zones)
{
	zone_count_t index;

	if (zones == NULL)
		return;

	vdo_free(vdo_forget(zones->manager));

	for (index = 0; index < zones->zone_count; index++)
		vdo_int_map_free(vdo_forget(zones->zones[index].lbn_operations));

	vdo_free(zones);
}

static inline void assert_on_zone_thread(struct logical_zone *zone, const char *what)
{
	VDO_ASSERT_LOG_ONLY((vdo_get_callback_thread_id() == zone->thread_id),
			    "%s() called on correct thread", what);
}

/**
 * check_for_drain_complete() - Check whether this zone has drained.
 * @zone: The zone to check.
 */
static void check_for_drain_complete(struct logical_zone *zone)
{
	if (!vdo_is_state_draining(&zone->state) || zone->notifying ||
	    !list_empty(&zone->write_vios))
		return;

	vdo_finish_draining(&zone->state);
}

/**
 * initiate_drain() - Initiate a drain.
 *
 * Implements vdo_admin_initiator_fn.
 */
static void initiate_drain(struct admin_state *state)
{
	check_for_drain_complete(container_of(state, struct logical_zone, state));
}

/**
 * drain_logical_zone() - Drain a logical zone.
 *
 * Implements vdo_zone_action_fn.
 */
static void drain_logical_zone(void *context, zone_count_t zone_number,
			       struct vdo_completion *parent)
{
	struct logical_zones *zones = context;

	vdo_start_draining(&zones->zones[zone_number].state,
			   vdo_get_current_manager_operation(zones->manager), parent,
			   initiate_drain);
}

void vdo_drain_logical_zones(struct logical_zones *zones,
			     const struct admin_state_code *operation,
			     struct vdo_completion *parent)
{
	vdo_schedule_operation(zones->manager, operation, NULL, drain_logical_zone, NULL,
			       parent);
}

/**
 * resume_logical_zone() - Resume a logical zone.
 *
 * Implements vdo_zone_action_fn.
 */
static void resume_logical_zone(void *context, zone_count_t zone_number,
				struct vdo_completion *parent)
{
	struct logical_zone *zone = &(((struct logical_zones *) context)->zones[zone_number]);

	vdo_fail_completion(parent, vdo_resume_if_quiescent(&zone->state));
}

/**
 * vdo_resume_logical_zones() - Resume a set of logical zones.
 * @zones: The logical zones to resume.
 * @parent: The object to notify when the zones have resumed.
 */
void vdo_resume_logical_zones(struct logical_zones *zones, struct vdo_completion *parent)
{
	vdo_schedule_operation(zones->manager, VDO_ADMIN_STATE_RESUMING, NULL,
			       resume_logical_zone, NULL, parent);
}

/**
 * update_oldest_active_generation() - Update the oldest active generation.
 * @zone: The zone.
 *
 * Return: true if the oldest active generation has changed.
 */
static bool update_oldest_active_generation(struct logical_zone *zone)
{
	struct data_vio *data_vio =
		list_first_entry_or_null(&zone->write_vios, struct data_vio,
					 write_entry);
	sequence_number_t oldest =
		(data_vio == NULL) ? zone->flush_generation : data_vio->flush_generation;

	if (oldest == zone->oldest_active_generation)
		return false;

	WRITE_ONCE(zone->oldest_active_generation, oldest);
	return true;
}

/**
 * vdo_increment_logical_zone_flush_generation() - Increment the flush generation in a logical
 *                                                 zone.
 * @zone: The logical zone.
 * @expected_generation: The expected value of the flush generation before the increment.
 */
void vdo_increment_logical_zone_flush_generation(struct logical_zone *zone,
						 sequence_number_t expected_generation)
{
	assert_on_zone_thread(zone, __func__);
	VDO_ASSERT_LOG_ONLY((zone->flush_generation == expected_generation),
			    "logical zone %u flush generation %llu should be %llu before increment",
			    zone->zone_number, (unsigned long long) zone->flush_generation,
			    (unsigned long long) expected_generation);

	zone->flush_generation++;
	zone->ios_in_flush_generation = 0;
	update_oldest_active_generation(zone);
}

/**
 * vdo_acquire_flush_generation_lock() - Acquire the shared lock on a flush generation by a write
 *                                       data_vio.
 * @data_vio: The data_vio.
 */
void vdo_acquire_flush_generation_lock(struct data_vio *data_vio)
{
	struct logical_zone *zone = data_vio->logical.zone;

	assert_on_zone_thread(zone, __func__);
	VDO_ASSERT_LOG_ONLY(vdo_is_state_normal(&zone->state), "vdo state is normal");

	data_vio->flush_generation = zone->flush_generation;
	list_add_tail(&data_vio->write_entry, &zone->write_vios);
	zone->ios_in_flush_generation++;
}

static void attempt_generation_complete_notification(struct vdo_completion *completion);

/**
 * notify_flusher() - Notify the flush that at least one generation no longer has active VIOs.
 * @completion: The zone completion.
 *
 * This callback is registered in attempt_generation_complete_notification().
 */
static void notify_flusher(struct vdo_completion *completion)
{
	struct logical_zone *zone = as_logical_zone(completion);

	vdo_complete_flushes(zone->zones->vdo->flusher);
	vdo_launch_completion_callback(completion,
				       attempt_generation_complete_notification,
				       zone->thread_id);
}

/**
 * attempt_generation_complete_notification() - Notify the flusher if some generation no
 *                                              longer has active VIOs.
 * @completion: The zone completion.
 */
static void attempt_generation_complete_notification(struct vdo_completion *completion)
{
	struct logical_zone *zone = as_logical_zone(completion);

	assert_on_zone_thread(zone, __func__);
	if (zone->oldest_active_generation <= zone->notification_generation) {
		zone->notifying = false;
		check_for_drain_complete(zone);
		return;
	}

	zone->notifying = true;
	zone->notification_generation = zone->oldest_active_generation;
	vdo_launch_completion_callback(&zone->completion, notify_flusher,
				       vdo_get_flusher_thread_id(zone->zones->vdo->flusher));
}

/**
 * vdo_release_flush_generation_lock() - Release the shared lock on a flush generation held by a
 *                                       write data_vio.
 * @data_vio: The data_vio whose lock is to be released.
 *
 * If there are pending flushes, and this data_vio completes the oldest generation active in this
 * zone, an attempt will be made to finish any flushes which may now be complete.
 */
void vdo_release_flush_generation_lock(struct data_vio *data_vio)
{
	struct logical_zone *zone = data_vio->logical.zone;

	assert_on_zone_thread(zone, __func__);

	if (!data_vio_has_flush_generation_lock(data_vio))
		return;

	list_del_init(&data_vio->write_entry);
	VDO_ASSERT_LOG_ONLY((zone->oldest_active_generation <= data_vio->flush_generation),
			    "data_vio releasing lock on generation %llu is not older than oldest active generation %llu",
			    (unsigned long long) data_vio->flush_generation,
			    (unsigned long long) zone->oldest_active_generation);

	if (!update_oldest_active_generation(zone) || zone->notifying)
		return;

	attempt_generation_complete_notification(&zone->completion);
}

struct physical_zone *vdo_get_next_allocation_zone(struct logical_zone *zone)
{
	if (zone->allocation_count == ALLOCATIONS_PER_ZONE) {
		zone->allocation_count = 0;
		zone->allocation_zone = zone->allocation_zone->next;
	}

	zone->allocation_count++;
	return zone->allocation_zone;
}

/**
 * vdo_dump_logical_zone() - Dump information about a logical zone to the log for debugging.
 * @zone: The zone to dump
 *
 * Context: the information is dumped in a thread-unsafe fashion.
 *
 */
void vdo_dump_logical_zone(const struct logical_zone *zone)
{
	vdo_log_info("logical_zone %u", zone->zone_number);
	vdo_log_info("  flush_generation=%llu oldest_active_generation=%llu notification_generation=%llu notifying=%s ios_in_flush_generation=%llu",
		     (unsigned long long) READ_ONCE(zone->flush_generation),
		     (unsigned long long) READ_ONCE(zone->oldest_active_generation),
		     (unsigned long long) READ_ONCE(zone->notification_generation),
		     vdo_bool_to_string(READ_ONCE(zone->notifying)),
		     (unsigned long long) READ_ONCE(zone->ios_in_flush_generation));
}