// SPDX-License-Identifier: GPL-2.0
#include <linux/vmalloc.h>
#include <linux/bitmap.h>
#include "null_blk.h"

#define CREATE_TRACE_POINTS
#include "trace.h"

#undef pr_fmt
#define pr_fmt(fmt)     "null_blk: " fmt

#define NULL_ZONE_INVALID_WP    ((sector_t)-1)

static inline sector_t mb_to_sects(unsigned long mb)
{
        return ((sector_t)mb * SZ_1M) >> SECTOR_SHIFT;
}

static inline unsigned int null_zone_no(struct nullb_device *dev, sector_t sect)
{
        return sect >> ilog2(dev->zone_size_sects);
}

static inline void null_init_zone_lock(struct nullb_device *dev,
                                       struct nullb_zone *zone)
{
        if (!dev->memory_backed)
                spin_lock_init(&zone->spinlock);
        else
                mutex_init(&zone->mutex);
}

static inline void null_lock_zone(struct nullb_device *dev,
                                  struct nullb_zone *zone)
{
        if (!dev->memory_backed)
                spin_lock_irq(&zone->spinlock);
        else
                mutex_lock(&zone->mutex);
}

static inline void null_unlock_zone(struct nullb_device *dev,
                                    struct nullb_zone *zone)
{
        if (!dev->memory_backed)
                spin_unlock_irq(&zone->spinlock);
        else
                mutex_unlock(&zone->mutex);
}

int null_init_zoned_dev(struct nullb_device *dev,
                        struct queue_limits *lim)
{
        sector_t dev_capacity_sects, zone_capacity_sects;
        struct nullb_zone *zone;
        sector_t sector = 0;
        unsigned int i;

        if (!is_power_of_2(dev->zone_size)) {
                pr_err("zone_size must be power-of-two\n");
                return -EINVAL;
        }
        if (dev->zone_size > dev->size) {
                pr_err("Zone size larger than device capacity\n");
                return -EINVAL;
        }

        if (!dev->zone_capacity)
                dev->zone_capacity = dev->zone_size;

        if (dev->zone_capacity > dev->zone_size) {
                pr_err("zone capacity (%lu MB) larger than zone size (%lu MB)\n",
                       dev->zone_capacity, dev->zone_size);
                return -EINVAL;
        }

        /*
         * If a smaller zone capacity was requested, do not allow a smaller last
         * zone at the same time as such zone configuration does not correspond
         * to any real zoned device.
         */
        if (dev->zone_capacity != dev->zone_size &&
            dev->size & (dev->zone_size - 1)) {
                pr_err("A smaller last zone is not allowed with zone capacity smaller than zone size.\n");
                return -EINVAL;
        }

        zone_capacity_sects = mb_to_sects(dev->zone_capacity);
        dev_capacity_sects = mb_to_sects(dev->size);
        dev->zone_size_sects = mb_to_sects(dev->zone_size);
        dev->nr_zones = round_up(dev_capacity_sects, dev->zone_size_sects)
                >> ilog2(dev->zone_size_sects);

        dev->zones = kvmalloc_objs(struct nullb_zone, dev->nr_zones,
                                   GFP_KERNEL | __GFP_ZERO);
        if (!dev->zones)
                return -ENOMEM;

        spin_lock_init(&dev->zone_res_lock);

        if (dev->zone_nr_conv >= dev->nr_zones) {
                dev->zone_nr_conv = dev->nr_zones - 1;
                pr_info("changed the number of conventional zones to %u",
                        dev->zone_nr_conv);
        }

        dev->zone_append_max_sectors =
                min(ALIGN_DOWN(dev->zone_append_max_sectors,
                               dev->blocksize >> SECTOR_SHIFT),
                    zone_capacity_sects);

        /* Max active zones has to be < nbr of seq zones in order to be enforceable */
        if (dev->zone_max_active >= dev->nr_zones - dev->zone_nr_conv) {
                dev->zone_max_active = 0;
                pr_info("zone_max_active limit disabled, limit >= zone count\n");
        }

        /* Max open zones has to be <= max active zones */
        if (dev->zone_max_active && dev->zone_max_open > dev->zone_max_active) {
                dev->zone_max_open = dev->zone_max_active;
                pr_info("changed the maximum number of open zones to %u\n",
                        dev->zone_max_open);
        } else if (dev->zone_max_open >= dev->nr_zones - dev->zone_nr_conv) {
                dev->zone_max_open = 0;
                pr_info("zone_max_open limit disabled, limit >= zone count\n");
        }
        dev->need_zone_res_mgmt = dev->zone_max_active || dev->zone_max_open;
        dev->imp_close_zone_no = dev->zone_nr_conv;

        for (i = 0; i <  dev->zone_nr_conv; i++) {
                zone = &dev->zones[i];

                null_init_zone_lock(dev, zone);
                zone->start = sector;
                zone->len = dev->zone_size_sects;
                zone->capacity = zone->len;
                zone->wp = zone->start + zone->len;
                zone->type = BLK_ZONE_TYPE_CONVENTIONAL;
                zone->cond = BLK_ZONE_COND_NOT_WP;

                sector += dev->zone_size_sects;
        }

        for (i = dev->zone_nr_conv; i < dev->nr_zones; i++) {
                zone = &dev->zones[i];

                null_init_zone_lock(dev, zone);
                zone->start = sector;
                if (zone->start + dev->zone_size_sects > dev_capacity_sects)
                        zone->len = dev_capacity_sects - zone->start;
                else
                        zone->len = dev->zone_size_sects;
                zone->capacity =
                        min_t(sector_t, zone->len, zone_capacity_sects);
                zone->type = BLK_ZONE_TYPE_SEQWRITE_REQ;
                if (dev->zone_full) {
                        zone->cond = BLK_ZONE_COND_FULL;
                        zone->wp = zone->start + zone->capacity;
                } else{
                        zone->cond = BLK_ZONE_COND_EMPTY;
                        zone->wp = zone->start;
                }

                sector += dev->zone_size_sects;
        }

        lim->features |= BLK_FEAT_ZONED;
        lim->chunk_sectors = dev->zone_size_sects;
        lim->max_hw_zone_append_sectors = dev->zone_append_max_sectors;
        lim->max_open_zones = dev->zone_max_open;
        lim->max_active_zones = dev->zone_max_active;
        return 0;
}

int null_register_zoned_dev(struct nullb *nullb)
{
        struct request_queue *q = nullb->q;
        struct gendisk *disk = nullb->disk;

        pr_info("%s: using %s zone append\n",
                disk->disk_name,
                queue_emulates_zone_append(q) ? "emulated" : "native");

        return blk_revalidate_disk_zones(disk);
}

void null_free_zoned_dev(struct nullb_device *dev)
{
        kvfree(dev->zones);
        dev->zones = NULL;
}

int null_report_zones(struct gendisk *disk, sector_t sector,
                unsigned int nr_zones, struct blk_report_zones_args *args)
{
        struct nullb *nullb = disk->private_data;
        struct nullb_device *dev = nullb->dev;
        unsigned int first_zone, i;
        struct nullb_zone *zone;
        struct blk_zone blkz;
        int error;

        first_zone = null_zone_no(dev, sector);
        if (first_zone >= dev->nr_zones)
                return 0;

        nr_zones = min(nr_zones, dev->nr_zones - first_zone);
        trace_nullb_report_zones(nullb, nr_zones);

        memset(&blkz, 0, sizeof(struct blk_zone));
        zone = &dev->zones[first_zone];
        for (i = 0; i < nr_zones; i++, zone++) {
                /*
                 * Stacked DM target drivers will remap the zone information by
                 * modifying the zone information passed to the report callback.
                 * So use a local copy to avoid corruption of the device zone
                 * array.
                 */
                null_lock_zone(dev, zone);
                blkz.start = zone->start;
                blkz.len = zone->len;
                blkz.wp = zone->wp;
                blkz.type = zone->type;
                blkz.cond = zone->cond;
                blkz.capacity = zone->capacity;
                null_unlock_zone(dev, zone);

                error = disk_report_zone(disk, &blkz, i, args);
                if (error)
                        return error;
        }

        return nr_zones;
}

/*
 * This is called in the case of memory backing from null_process_cmd()
 * with the target zone already locked.
 */
size_t null_zone_valid_read_len(struct nullb *nullb,
                                sector_t sector, unsigned int len)
{
        struct nullb_device *dev = nullb->dev;
        struct nullb_zone *zone = &dev->zones[null_zone_no(dev, sector)];
        unsigned int nr_sectors = DIV_ROUND_UP(len, SECTOR_SIZE);

        /* Read must be below the write pointer position */
        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL ||
            sector + nr_sectors <= zone->wp)
                return len;

        if (sector > zone->wp)
                return 0;

        return (zone->wp - sector) << SECTOR_SHIFT;
}

static void null_close_imp_open_zone(struct nullb_device *dev)
{
        struct nullb_zone *zone;
        unsigned int zno, i;

        zno = dev->imp_close_zone_no;
        if (zno >= dev->nr_zones)
                zno = dev->zone_nr_conv;

        for (i = dev->zone_nr_conv; i < dev->nr_zones; i++) {
                zone = &dev->zones[zno];
                zno++;
                if (zno >= dev->nr_zones)
                        zno = dev->zone_nr_conv;

                if (zone->cond == BLK_ZONE_COND_IMP_OPEN) {
                        dev->nr_zones_imp_open--;
                        if (zone->wp == zone->start) {
                                zone->cond = BLK_ZONE_COND_EMPTY;
                        } else {
                                zone->cond = BLK_ZONE_COND_CLOSED;
                                dev->nr_zones_closed++;
                        }
                        dev->imp_close_zone_no = zno;
                        return;
                }
        }
}

static blk_status_t null_check_active(struct nullb_device *dev)
{
        if (!dev->zone_max_active)
                return BLK_STS_OK;

        if (dev->nr_zones_exp_open + dev->nr_zones_imp_open +
                        dev->nr_zones_closed < dev->zone_max_active)
                return BLK_STS_OK;

        return BLK_STS_ZONE_ACTIVE_RESOURCE;
}

static blk_status_t null_check_open(struct nullb_device *dev)
{
        if (!dev->zone_max_open)
                return BLK_STS_OK;

        if (dev->nr_zones_exp_open + dev->nr_zones_imp_open < dev->zone_max_open)
                return BLK_STS_OK;

        if (dev->nr_zones_imp_open) {
                if (null_check_active(dev) == BLK_STS_OK) {
                        null_close_imp_open_zone(dev);
                        return BLK_STS_OK;
                }
        }

        return BLK_STS_ZONE_OPEN_RESOURCE;
}

/*
 * This function matches the manage open zone resources function in the ZBC standard,
 * with the addition of max active zones support (added in the ZNS standard).
 *
 * The function determines if a zone can transition to implicit open or explicit open,
 * while maintaining the max open zone (and max active zone) limit(s). It may close an
 * implicit open zone in order to make additional zone resources available.
 *
 * ZBC states that an implicit open zone shall be closed only if there is not
 * room within the open limit. However, with the addition of an active limit,
 * it is not certain that closing an implicit open zone will allow a new zone
 * to be opened, since we might already be at the active limit capacity.
 */
static blk_status_t null_check_zone_resources(struct nullb_device *dev,
                                              struct nullb_zone *zone)
{
        blk_status_t ret;

        switch (zone->cond) {
        case BLK_ZONE_COND_EMPTY:
                ret = null_check_active(dev);
                if (ret != BLK_STS_OK)
                        return ret;
                fallthrough;
        case BLK_ZONE_COND_CLOSED:
                return null_check_open(dev);
        default:
                /* Should never be called for other states */
                WARN_ON(1);
                return BLK_STS_IOERR;
        }
}

static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
                                    unsigned int nr_sectors, bool append)
{
        struct nullb_device *dev = cmd->nq->dev;
        unsigned int zno = null_zone_no(dev, sector);
        struct nullb_zone *zone = &dev->zones[zno];
        blk_status_t badblocks_ret = BLK_STS_OK;
        blk_status_t ret;

        trace_nullb_zone_op(cmd, zno, zone->cond);

        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL) {
                if (append)
                        return BLK_STS_IOERR;
                return null_process_cmd(cmd, REQ_OP_WRITE, sector, nr_sectors);
        }

        null_lock_zone(dev, zone);

        /*
         * Regular writes must be at the write pointer position. Zone append
         * writes are automatically issued at the write pointer and the position
         * returned using the request sector. Note that we do not check the zone
         * condition because for FULL, READONLY and OFFLINE zones, the sector
         * check against the zone write pointer will always result in failing
         * the command.
         */
        if (append) {
                if (WARN_ON_ONCE(!dev->zone_append_max_sectors) ||
                    zone->wp == NULL_ZONE_INVALID_WP) {
                        ret = BLK_STS_IOERR;
                        goto unlock_zone;
                }
                sector = zone->wp;
                blk_mq_rq_from_pdu(cmd)->__sector = sector;
        }

        if (sector != zone->wp ||
            zone->wp + nr_sectors > zone->start + zone->capacity) {
                ret = BLK_STS_IOERR;
                goto unlock_zone;
        }

        if (zone->cond == BLK_ZONE_COND_CLOSED ||
            zone->cond == BLK_ZONE_COND_EMPTY) {
                if (dev->need_zone_res_mgmt) {
                        spin_lock(&dev->zone_res_lock);

                        ret = null_check_zone_resources(dev, zone);
                        if (ret != BLK_STS_OK) {
                                spin_unlock(&dev->zone_res_lock);
                                goto unlock_zone;
                        }
                        if (zone->cond == BLK_ZONE_COND_CLOSED) {
                                dev->nr_zones_closed--;
                                dev->nr_zones_imp_open++;
                        } else if (zone->cond == BLK_ZONE_COND_EMPTY) {
                                dev->nr_zones_imp_open++;
                        }

                        spin_unlock(&dev->zone_res_lock);
                }

                zone->cond = BLK_ZONE_COND_IMP_OPEN;
        }

        if (dev->badblocks.shift != -1) {
                badblocks_ret = null_handle_badblocks(cmd, sector, &nr_sectors);
                if (badblocks_ret != BLK_STS_OK && !nr_sectors) {
                        ret = badblocks_ret;
                        goto unlock_zone;
                }
        }

        if (dev->memory_backed) {
                ret = null_handle_memory_backed(cmd, REQ_OP_WRITE, sector,
                                                nr_sectors);
                if (ret != BLK_STS_OK)
                        goto unlock_zone;
        }

        zone->wp += nr_sectors;
        if (zone->wp == zone->start + zone->capacity) {
                if (dev->need_zone_res_mgmt) {
                        spin_lock(&dev->zone_res_lock);
                        if (zone->cond == BLK_ZONE_COND_EXP_OPEN)
                                dev->nr_zones_exp_open--;
                        else if (zone->cond == BLK_ZONE_COND_IMP_OPEN)
                                dev->nr_zones_imp_open--;
                        spin_unlock(&dev->zone_res_lock);
                }
                zone->cond = BLK_ZONE_COND_FULL;
        }

        ret = badblocks_ret;

unlock_zone:
        null_unlock_zone(dev, zone);

        return ret;
}

static blk_status_t null_open_zone(struct nullb_device *dev,
                                   struct nullb_zone *zone)
{
        blk_status_t ret = BLK_STS_OK;

        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
                return BLK_STS_IOERR;

        switch (zone->cond) {
        case BLK_ZONE_COND_EXP_OPEN:
                /* Open operation on exp open is not an error */
                return BLK_STS_OK;
        case BLK_ZONE_COND_EMPTY:
        case BLK_ZONE_COND_IMP_OPEN:
        case BLK_ZONE_COND_CLOSED:
                break;
        case BLK_ZONE_COND_FULL:
        default:
                return BLK_STS_IOERR;
        }

        if (dev->need_zone_res_mgmt) {
                spin_lock(&dev->zone_res_lock);

                switch (zone->cond) {
                case BLK_ZONE_COND_EMPTY:
                        ret = null_check_zone_resources(dev, zone);
                        if (ret != BLK_STS_OK) {
                                spin_unlock(&dev->zone_res_lock);
                                return ret;
                        }
                        break;
                case BLK_ZONE_COND_IMP_OPEN:
                        dev->nr_zones_imp_open--;
                        break;
                case BLK_ZONE_COND_CLOSED:
                        ret = null_check_zone_resources(dev, zone);
                        if (ret != BLK_STS_OK) {
                                spin_unlock(&dev->zone_res_lock);
                                return ret;
                        }
                        dev->nr_zones_closed--;
                        break;
                default:
                        break;
                }

                dev->nr_zones_exp_open++;

                spin_unlock(&dev->zone_res_lock);
        }

        zone->cond = BLK_ZONE_COND_EXP_OPEN;

        return BLK_STS_OK;
}

static blk_status_t null_close_zone(struct nullb_device *dev,
                                    struct nullb_zone *zone)
{
        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
                return BLK_STS_IOERR;

        switch (zone->cond) {
        case BLK_ZONE_COND_CLOSED:
                /* close operation on closed is not an error */
                return BLK_STS_OK;
        case BLK_ZONE_COND_IMP_OPEN:
        case BLK_ZONE_COND_EXP_OPEN:
                break;
        case BLK_ZONE_COND_EMPTY:
        case BLK_ZONE_COND_FULL:
        default:
                return BLK_STS_IOERR;
        }

        if (dev->need_zone_res_mgmt) {
                spin_lock(&dev->zone_res_lock);

                switch (zone->cond) {
                case BLK_ZONE_COND_IMP_OPEN:
                        dev->nr_zones_imp_open--;
                        break;
                case BLK_ZONE_COND_EXP_OPEN:
                        dev->nr_zones_exp_open--;
                        break;
                default:
                        break;
                }

                if (zone->wp > zone->start)
                        dev->nr_zones_closed++;

                spin_unlock(&dev->zone_res_lock);
        }

        if (zone->wp == zone->start)
                zone->cond = BLK_ZONE_COND_EMPTY;
        else
                zone->cond = BLK_ZONE_COND_CLOSED;

        return BLK_STS_OK;
}

static blk_status_t null_finish_zone(struct nullb_device *dev,
                                     struct nullb_zone *zone)
{
        blk_status_t ret = BLK_STS_OK;

        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
                return BLK_STS_IOERR;

        if (dev->need_zone_res_mgmt) {
                spin_lock(&dev->zone_res_lock);

                switch (zone->cond) {
                case BLK_ZONE_COND_FULL:
                        /* Finish operation on full is not an error */
                        spin_unlock(&dev->zone_res_lock);
                        return BLK_STS_OK;
                case BLK_ZONE_COND_EMPTY:
                        ret = null_check_zone_resources(dev, zone);
                        if (ret != BLK_STS_OK) {
                                spin_unlock(&dev->zone_res_lock);
                                return ret;
                        }
                        break;
                case BLK_ZONE_COND_IMP_OPEN:
                        dev->nr_zones_imp_open--;
                        break;
                case BLK_ZONE_COND_EXP_OPEN:
                        dev->nr_zones_exp_open--;
                        break;
                case BLK_ZONE_COND_CLOSED:
                        ret = null_check_zone_resources(dev, zone);
                        if (ret != BLK_STS_OK) {
                                spin_unlock(&dev->zone_res_lock);
                                return ret;
                        }
                        dev->nr_zones_closed--;
                        break;
                default:
                        spin_unlock(&dev->zone_res_lock);
                        return BLK_STS_IOERR;
                }

                spin_unlock(&dev->zone_res_lock);
        }

        zone->cond = BLK_ZONE_COND_FULL;
        zone->wp = zone->start + zone->len;

        return BLK_STS_OK;
}

static blk_status_t null_reset_zone(struct nullb_device *dev,
                                    struct nullb_zone *zone)
{
        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
                return BLK_STS_IOERR;

        if (dev->need_zone_res_mgmt) {
                spin_lock(&dev->zone_res_lock);

                switch (zone->cond) {
                case BLK_ZONE_COND_IMP_OPEN:
                        dev->nr_zones_imp_open--;
                        break;
                case BLK_ZONE_COND_EXP_OPEN:
                        dev->nr_zones_exp_open--;
                        break;
                case BLK_ZONE_COND_CLOSED:
                        dev->nr_zones_closed--;
                        break;
                case BLK_ZONE_COND_EMPTY:
                case BLK_ZONE_COND_FULL:
                        break;
                default:
                        spin_unlock(&dev->zone_res_lock);
                        return BLK_STS_IOERR;
                }

                spin_unlock(&dev->zone_res_lock);
        }

        zone->cond = BLK_ZONE_COND_EMPTY;
        zone->wp = zone->start;

        if (dev->memory_backed)
                return null_handle_discard(dev, zone->start, zone->len);

        return BLK_STS_OK;
}

static blk_status_t null_zone_mgmt(struct nullb_cmd *cmd, enum req_op op,
                                   sector_t sector)
{
        struct nullb_device *dev = cmd->nq->dev;
        unsigned int zone_no;
        struct nullb_zone *zone;
        blk_status_t ret;
        size_t i;

        if (op == REQ_OP_ZONE_RESET_ALL) {
                for (i = dev->zone_nr_conv; i < dev->nr_zones; i++) {
                        zone = &dev->zones[i];
                        null_lock_zone(dev, zone);
                        if (zone->cond != BLK_ZONE_COND_EMPTY &&
                            zone->cond != BLK_ZONE_COND_READONLY &&
                            zone->cond != BLK_ZONE_COND_OFFLINE) {
                                null_reset_zone(dev, zone);
                                trace_nullb_zone_op(cmd, i, zone->cond);
                        }
                        null_unlock_zone(dev, zone);
                }
                return BLK_STS_OK;
        }

        zone_no = null_zone_no(dev, sector);
        zone = &dev->zones[zone_no];

        null_lock_zone(dev, zone);

        if (zone->cond == BLK_ZONE_COND_READONLY ||
            zone->cond == BLK_ZONE_COND_OFFLINE) {
                ret = BLK_STS_IOERR;
                goto unlock;
        }

        switch (op) {
        case REQ_OP_ZONE_RESET:
                ret = null_reset_zone(dev, zone);
                break;
        case REQ_OP_ZONE_OPEN:
                ret = null_open_zone(dev, zone);
                break;
        case REQ_OP_ZONE_CLOSE:
                ret = null_close_zone(dev, zone);
                break;
        case REQ_OP_ZONE_FINISH:
                ret = null_finish_zone(dev, zone);
                break;
        default:
                ret = BLK_STS_NOTSUPP;
                break;
        }

        if (ret == BLK_STS_OK)
                trace_nullb_zone_op(cmd, zone_no, zone->cond);

unlock:
        null_unlock_zone(dev, zone);

        return ret;
}

blk_status_t null_process_zoned_cmd(struct nullb_cmd *cmd, enum req_op op,
                                    sector_t sector, sector_t nr_sectors)
{
        struct nullb_device *dev;
        struct nullb_zone *zone;
        blk_status_t sts;

        switch (op) {
        case REQ_OP_WRITE:
                return null_zone_write(cmd, sector, nr_sectors, false);
        case REQ_OP_ZONE_APPEND:
                return null_zone_write(cmd, sector, nr_sectors, true);
        case REQ_OP_ZONE_RESET:
        case REQ_OP_ZONE_RESET_ALL:
        case REQ_OP_ZONE_OPEN:
        case REQ_OP_ZONE_CLOSE:
        case REQ_OP_ZONE_FINISH:
                return null_zone_mgmt(cmd, op, sector);
        default:
                dev = cmd->nq->dev;
                zone = &dev->zones[null_zone_no(dev, sector)];
                if (zone->cond == BLK_ZONE_COND_OFFLINE)
                        return BLK_STS_IOERR;

                null_lock_zone(dev, zone);
                sts = null_process_cmd(cmd, op, sector, nr_sectors);
                null_unlock_zone(dev, zone);
                return sts;
        }
}

/*
 * Set a zone in the read-only or offline condition.
 */
static void null_set_zone_cond(struct nullb_device *dev,
                               struct nullb_zone *zone, enum blk_zone_cond cond)
{
        if (WARN_ON_ONCE(cond != BLK_ZONE_COND_READONLY &&
                         cond != BLK_ZONE_COND_OFFLINE))
                return;

        null_lock_zone(dev, zone);

        /*
         * If the read-only condition is requested again to zones already in
         * read-only condition, restore back normal empty condition. Do the same
         * if the offline condition is requested for offline zones. Otherwise,
         * set the specified zone condition to the zones. Finish the zones
         * beforehand to free up zone resources.
         */
        if (zone->cond == cond) {
                zone->cond = BLK_ZONE_COND_EMPTY;
                zone->wp = zone->start;
                if (dev->memory_backed)
                        null_handle_discard(dev, zone->start, zone->len);
        } else {
                if (zone->cond != BLK_ZONE_COND_READONLY &&
                    zone->cond != BLK_ZONE_COND_OFFLINE)
                        null_finish_zone(dev, zone);
                zone->cond = cond;
                zone->wp = NULL_ZONE_INVALID_WP;
        }

        null_unlock_zone(dev, zone);
}

/*
 * Identify a zone from the sector written to configfs file. Then set zone
 * condition to the zone.
 */
ssize_t zone_cond_store(struct nullb_device *dev, const char *page,
                        size_t count, enum blk_zone_cond cond)
{
        unsigned long long sector;
        unsigned int zone_no;
        int ret;

        if (!dev->zoned) {
                pr_err("null_blk device is not zoned\n");
                return -EINVAL;
        }

        if (!dev->zones) {
                pr_err("null_blk device is not yet powered\n");
                return -EINVAL;
        }

        ret = kstrtoull(page, 0, &sector);
        if (ret < 0)
                return ret;

        zone_no = null_zone_no(dev, sector);
        if (zone_no >= dev->nr_zones) {
                pr_err("Sector out of range\n");
                return -EINVAL;
        }

        if (dev->zones[zone_no].type == BLK_ZONE_TYPE_CONVENTIONAL) {
                pr_err("Can not change condition of conventional zones\n");
                return -EINVAL;
        }

        null_set_zone_cond(dev, &dev->zones[zone_no], cond);

        return count;
}