Merge tag 'block-5.11-2021-01-10' of git://git.kernel.dk/linux-block

[linux/fpc-iii.git] / drivers / scsi / sd_zbc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * SCSI Zoned Block commands
 *
 * Copyright (C) 2014-2015 SUSE Linux GmbH
 * Written by: Hannes Reinecke <hare@suse.de>
 * Modified by: Damien Le Moal <damien.lemoal@hgst.com>
 * Modified by: Shaun Tancheff <shaun.tancheff@seagate.com>
 */

#include <linux/blkdev.h>
#include <linux/vmalloc.h>
#include <linux/sched/mm.h>
#include <linux/mutex.h>

#include <asm/unaligned.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>

#include "sd.h"

static unsigned int sd_zbc_get_zone_wp_offset(struct blk_zone *zone)
{
        if (zone->type == ZBC_ZONE_TYPE_CONV)
                return 0;

        switch (zone->cond) {
        case BLK_ZONE_COND_IMP_OPEN:
        case BLK_ZONE_COND_EXP_OPEN:
        case BLK_ZONE_COND_CLOSED:
                return zone->wp - zone->start;
        case BLK_ZONE_COND_FULL:
                return zone->len;
        case BLK_ZONE_COND_EMPTY:
        case BLK_ZONE_COND_OFFLINE:
        case BLK_ZONE_COND_READONLY:
        default:
                /*
                 * Offline and read-only zones do not have a valid
                 * write pointer. Use 0 as for an empty zone.
                 */
                return 0;
        }
}

static int sd_zbc_parse_report(struct scsi_disk *sdkp, u8 *buf,
                               unsigned int idx, report_zones_cb cb, void *data)
{
        struct scsi_device *sdp = sdkp->device;
        struct blk_zone zone = { 0 };
        int ret;

        zone.type = buf[0] & 0x0f;
        zone.cond = (buf[1] >> 4) & 0xf;
        if (buf[1] & 0x01)
                zone.reset = 1;
        if (buf[1] & 0x02)
                zone.non_seq = 1;

        zone.len = logical_to_sectors(sdp, get_unaligned_be64(&buf[8]));
        zone.capacity = zone.len;
        zone.start = logical_to_sectors(sdp, get_unaligned_be64(&buf[16]));
        zone.wp = logical_to_sectors(sdp, get_unaligned_be64(&buf[24]));
        if (zone.type != ZBC_ZONE_TYPE_CONV &&
            zone.cond == ZBC_ZONE_COND_FULL)
                zone.wp = zone.start + zone.len;

        ret = cb(&zone, idx, data);
        if (ret)
                return ret;

        if (sdkp->rev_wp_offset)
                sdkp->rev_wp_offset[idx] = sd_zbc_get_zone_wp_offset(&zone);

        return 0;
}

/**
 * sd_zbc_do_report_zones - Issue a REPORT ZONES scsi command.
 * @sdkp: The target disk
 * @buf: vmalloc-ed buffer to use for the reply
 * @buflen: the buffer size
 * @lba: Start LBA of the report
 * @partial: Do partial report
 *
 * For internal use during device validation.
 * Using partial=true can significantly speed up execution of a report zones
 * command because the disk does not have to count all possible report matching
 * zones and will only report the count of zones fitting in the command reply
 * buffer.
 */
static int sd_zbc_do_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
                                  unsigned int buflen, sector_t lba,
                                  bool partial)
{
        struct scsi_device *sdp = sdkp->device;
        const int timeout = sdp->request_queue->rq_timeout;
        struct scsi_sense_hdr sshdr;
        unsigned char cmd[16];
        unsigned int rep_len;
        int result;

        memset(cmd, 0, 16);
        cmd[0] = ZBC_IN;
        cmd[1] = ZI_REPORT_ZONES;
        put_unaligned_be64(lba, &cmd[2]);
        put_unaligned_be32(buflen, &cmd[10]);
        if (partial)
                cmd[14] = ZBC_REPORT_ZONE_PARTIAL;

        result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,
                                  buf, buflen, &sshdr,
                                  timeout, SD_MAX_RETRIES, NULL);
        if (result) {
                sd_printk(KERN_ERR, sdkp,
                          "REPORT ZONES start lba %llu failed\n", lba);
                sd_print_result(sdkp, "REPORT ZONES", result);
                if (driver_byte(result) == DRIVER_SENSE &&
                    scsi_sense_valid(&sshdr))
                        sd_print_sense_hdr(sdkp, &sshdr);
                return -EIO;
        }

        rep_len = get_unaligned_be32(&buf[0]);
        if (rep_len < 64) {
                sd_printk(KERN_ERR, sdkp,
                          "REPORT ZONES report invalid length %u\n",
                          rep_len);
                return -EIO;
        }

        return 0;
}

/**
 * Allocate a buffer for report zones reply.
 * @sdkp: The target disk
 * @nr_zones: Maximum number of zones to report
 * @buflen: Size of the buffer allocated
 *
 * Try to allocate a reply buffer for the number of requested zones.
 * The size of the buffer allocated may be smaller than requested to
 * satify the device constraint (max_hw_sectors, max_segments, etc).
 *
 * Return the address of the allocated buffer and update @buflen with
 * the size of the allocated buffer.
 */
static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp,
                                        unsigned int nr_zones, size_t *buflen)
{
        struct request_queue *q = sdkp->disk->queue;
        size_t bufsize;
        void *buf;

        /*
         * Report zone buffer size should be at most 64B times the number of
         * zones requested plus the 64B reply header, but should be at least
         * SECTOR_SIZE for ATA devices.
         * Make sure that this size does not exceed the hardware capabilities.
         * Furthermore, since the report zone command cannot be split, make
         * sure that the allocated buffer can always be mapped by limiting the
         * number of pages allocated to the HBA max segments limit.
         */
        nr_zones = min(nr_zones, sdkp->nr_zones);
        bufsize = roundup((nr_zones + 1) * 64, SECTOR_SIZE);
        bufsize = min_t(size_t, bufsize,
                        queue_max_hw_sectors(q) << SECTOR_SHIFT);
        bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);

        while (bufsize >= SECTOR_SIZE) {
                buf = __vmalloc(bufsize,
                                GFP_KERNEL | __GFP_ZERO | __GFP_NORETRY);
                if (buf) {
                        *buflen = bufsize;
                        return buf;
                }
                bufsize >>= 1;
        }

        return NULL;
}

/**
 * sd_zbc_zone_sectors - Get the device zone size in number of 512B sectors.
 * @sdkp: The target disk
 */
static inline sector_t sd_zbc_zone_sectors(struct scsi_disk *sdkp)
{
        return logical_to_sectors(sdkp->device, sdkp->zone_blocks);
}

int sd_zbc_report_zones(struct gendisk *disk, sector_t sector,
                        unsigned int nr_zones, report_zones_cb cb, void *data)
{
        struct scsi_disk *sdkp = scsi_disk(disk);
        sector_t capacity = logical_to_sectors(sdkp->device, sdkp->capacity);
        unsigned int nr, i;
        unsigned char *buf;
        size_t offset, buflen = 0;
        int zone_idx = 0;
        int ret;

        if (!sd_is_zoned(sdkp))
                /* Not a zoned device */
                return -EOPNOTSUPP;

        if (!capacity)
                /* Device gone or invalid */
                return -ENODEV;

        buf = sd_zbc_alloc_report_buffer(sdkp, nr_zones, &buflen);
        if (!buf)
                return -ENOMEM;

        while (zone_idx < nr_zones && sector < capacity) {
                ret = sd_zbc_do_report_zones(sdkp, buf, buflen,
                                sectors_to_logical(sdkp->device, sector), true);
                if (ret)
                        goto out;

                offset = 0;
                nr = min(nr_zones, get_unaligned_be32(&buf[0]) / 64);
                if (!nr)
                        break;

                for (i = 0; i < nr && zone_idx < nr_zones; i++) {
                        offset += 64;
                        ret = sd_zbc_parse_report(sdkp, buf + offset, zone_idx,
                                                  cb, data);
                        if (ret)
                                goto out;
                        zone_idx++;
                }

                sector += sd_zbc_zone_sectors(sdkp) * i;
        }

        ret = zone_idx;
out:
        kvfree(buf);
        return ret;
}

static blk_status_t sd_zbc_cmnd_checks(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        sector_t sector = blk_rq_pos(rq);

        if (!sd_is_zoned(sdkp))
                /* Not a zoned device */
                return BLK_STS_IOERR;

        if (sdkp->device->changed)
                return BLK_STS_IOERR;

        if (sector & (sd_zbc_zone_sectors(sdkp) - 1))
                /* Unaligned request */
                return BLK_STS_IOERR;

        return BLK_STS_OK;
}

#define SD_ZBC_INVALID_WP_OFST  (~0u)
#define SD_ZBC_UPDATING_WP_OFST (SD_ZBC_INVALID_WP_OFST - 1)

static int sd_zbc_update_wp_offset_cb(struct blk_zone *zone, unsigned int idx,
                                    void *data)
{
        struct scsi_disk *sdkp = data;

        lockdep_assert_held(&sdkp->zones_wp_offset_lock);

        sdkp->zones_wp_offset[idx] = sd_zbc_get_zone_wp_offset(zone);

        return 0;
}

static void sd_zbc_update_wp_offset_workfn(struct work_struct *work)
{
        struct scsi_disk *sdkp;
        unsigned int zno;
        int ret;

        sdkp = container_of(work, struct scsi_disk, zone_wp_offset_work);

        spin_lock_bh(&sdkp->zones_wp_offset_lock);
        for (zno = 0; zno < sdkp->nr_zones; zno++) {
                if (sdkp->zones_wp_offset[zno] != SD_ZBC_UPDATING_WP_OFST)
                        continue;

                spin_unlock_bh(&sdkp->zones_wp_offset_lock);
                ret = sd_zbc_do_report_zones(sdkp, sdkp->zone_wp_update_buf,
                                             SD_BUF_SIZE,
                                             zno * sdkp->zone_blocks, true);
                spin_lock_bh(&sdkp->zones_wp_offset_lock);
                if (!ret)
                        sd_zbc_parse_report(sdkp, sdkp->zone_wp_update_buf + 64,
                                            zno, sd_zbc_update_wp_offset_cb,
                                            sdkp);
        }
        spin_unlock_bh(&sdkp->zones_wp_offset_lock);

        scsi_device_put(sdkp->device);
}

/**
 * sd_zbc_prepare_zone_append() - Prepare an emulated ZONE_APPEND command.
 * @cmd: the command to setup
 * @lba: the LBA to patch
 * @nr_blocks: the number of LBAs to be written
 *
 * Called from sd_setup_read_write_cmnd() for REQ_OP_ZONE_APPEND.
 * @sd_zbc_prepare_zone_append() handles the necessary zone wrote locking and
 * patching of the lba for an emulated ZONE_APPEND command.
 *
 * In case the cached write pointer offset is %SD_ZBC_INVALID_WP_OFST it will
 * schedule a REPORT ZONES command and return BLK_STS_IOERR.
 */
blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd, sector_t *lba,
                                        unsigned int nr_blocks)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        unsigned int wp_offset, zno = blk_rq_zone_no(rq);
        blk_status_t ret;

        ret = sd_zbc_cmnd_checks(cmd);
        if (ret != BLK_STS_OK)
                return ret;

        if (!blk_rq_zone_is_seq(rq))
                return BLK_STS_IOERR;

        /* Unlock of the write lock will happen in sd_zbc_complete() */
        if (!blk_req_zone_write_trylock(rq))
                return BLK_STS_ZONE_RESOURCE;

        spin_lock_bh(&sdkp->zones_wp_offset_lock);
        wp_offset = sdkp->zones_wp_offset[zno];
        switch (wp_offset) {
        case SD_ZBC_INVALID_WP_OFST:
                /*
                 * We are about to schedule work to update a zone write pointer
                 * offset, which will cause the zone append command to be
                 * requeued. So make sure that the scsi device does not go away
                 * while the work is being processed.
                 */
                if (scsi_device_get(sdkp->device)) {
                        ret = BLK_STS_IOERR;
                        break;
                }
                sdkp->zones_wp_offset[zno] = SD_ZBC_UPDATING_WP_OFST;
                schedule_work(&sdkp->zone_wp_offset_work);
                fallthrough;
        case SD_ZBC_UPDATING_WP_OFST:
                ret = BLK_STS_DEV_RESOURCE;
                break;
        default:
                wp_offset = sectors_to_logical(sdkp->device, wp_offset);
                if (wp_offset + nr_blocks > sdkp->zone_blocks) {
                        ret = BLK_STS_IOERR;
                        break;
                }

                *lba += wp_offset;
        }
        spin_unlock_bh(&sdkp->zones_wp_offset_lock);
        if (ret)
                blk_req_zone_write_unlock(rq);
        return ret;
}

/**
 * sd_zbc_setup_zone_mgmt_cmnd - Prepare a zone ZBC_OUT command. The operations
 *                      can be RESET WRITE POINTER, OPEN, CLOSE or FINISH.
 * @cmd: the command to setup
 * @op: Operation to be performed
 * @all: All zones control
 *
 * Called from sd_init_command() for REQ_OP_ZONE_RESET, REQ_OP_ZONE_RESET_ALL,
 * REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE or REQ_OP_ZONE_FINISH requests.
 */
blk_status_t sd_zbc_setup_zone_mgmt_cmnd(struct scsi_cmnd *cmd,
                                         unsigned char op, bool all)
{
        struct request *rq = cmd->request;
        sector_t sector = blk_rq_pos(rq);
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        sector_t block = sectors_to_logical(sdkp->device, sector);
        blk_status_t ret;

        ret = sd_zbc_cmnd_checks(cmd);
        if (ret != BLK_STS_OK)
                return ret;

        cmd->cmd_len = 16;
        memset(cmd->cmnd, 0, cmd->cmd_len);
        cmd->cmnd[0] = ZBC_OUT;
        cmd->cmnd[1] = op;
        if (all)
                cmd->cmnd[14] = 0x1;
        else
                put_unaligned_be64(block, &cmd->cmnd[2]);

        rq->timeout = SD_TIMEOUT;
        cmd->sc_data_direction = DMA_NONE;
        cmd->transfersize = 0;
        cmd->allowed = 0;

        return BLK_STS_OK;
}

static bool sd_zbc_need_zone_wp_update(struct request *rq)
{
        switch (req_op(rq)) {
        case REQ_OP_ZONE_APPEND:
        case REQ_OP_ZONE_FINISH:
        case REQ_OP_ZONE_RESET:
        case REQ_OP_ZONE_RESET_ALL:
                return true;
        case REQ_OP_WRITE:
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_WRITE_SAME:
                return blk_rq_zone_is_seq(rq);
        default:
                return false;
        }
}

/**
 * sd_zbc_zone_wp_update - Update cached zone write pointer upon cmd completion
 * @cmd: Completed command
 * @good_bytes: Command reply bytes
 *
 * Called from sd_zbc_complete() to handle the update of the cached zone write
 * pointer value in case an update is needed.
 */
static unsigned int sd_zbc_zone_wp_update(struct scsi_cmnd *cmd,
                                          unsigned int good_bytes)
{
        int result = cmd->result;
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        unsigned int zno = blk_rq_zone_no(rq);
        enum req_opf op = req_op(rq);

        /*
         * If we got an error for a command that needs updating the write
         * pointer offset cache, we must mark the zone wp offset entry as
         * invalid to force an update from disk the next time a zone append
         * command is issued.
         */
        spin_lock_bh(&sdkp->zones_wp_offset_lock);

        if (result && op != REQ_OP_ZONE_RESET_ALL) {
                if (op == REQ_OP_ZONE_APPEND) {
                        /* Force complete completion (no retry) */
                        good_bytes = 0;
                        scsi_set_resid(cmd, blk_rq_bytes(rq));
                }

                /*
                 * Force an update of the zone write pointer offset on
                 * the next zone append access.
                 */
                if (sdkp->zones_wp_offset[zno] != SD_ZBC_UPDATING_WP_OFST)
                        sdkp->zones_wp_offset[zno] = SD_ZBC_INVALID_WP_OFST;
                goto unlock_wp_offset;
        }

        switch (op) {
        case REQ_OP_ZONE_APPEND:
                rq->__sector += sdkp->zones_wp_offset[zno];
                fallthrough;
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_WRITE_SAME:
        case REQ_OP_WRITE:
                if (sdkp->zones_wp_offset[zno] < sd_zbc_zone_sectors(sdkp))
                        sdkp->zones_wp_offset[zno] +=
                                                good_bytes >> SECTOR_SHIFT;
                break;
        case REQ_OP_ZONE_RESET:
                sdkp->zones_wp_offset[zno] = 0;
                break;
        case REQ_OP_ZONE_FINISH:
                sdkp->zones_wp_offset[zno] = sd_zbc_zone_sectors(sdkp);
                break;
        case REQ_OP_ZONE_RESET_ALL:
                memset(sdkp->zones_wp_offset, 0,
                       sdkp->nr_zones * sizeof(unsigned int));
                break;
        default:
                break;
        }

unlock_wp_offset:
        spin_unlock_bh(&sdkp->zones_wp_offset_lock);

        return good_bytes;
}

/**
 * sd_zbc_complete - ZBC command post processing.
 * @cmd: Completed command
 * @good_bytes: Command reply bytes
 * @sshdr: command sense header
 *
 * Called from sd_done() to handle zone commands errors and updates to the
 * device queue zone write pointer offset cahce.
 */
unsigned int sd_zbc_complete(struct scsi_cmnd *cmd, unsigned int good_bytes,
                     struct scsi_sense_hdr *sshdr)
{
        int result = cmd->result;
        struct request *rq = cmd->request;

        if (op_is_zone_mgmt(req_op(rq)) &&
            result &&
            sshdr->sense_key == ILLEGAL_REQUEST &&
            sshdr->asc == 0x24) {
                /*
                 * INVALID FIELD IN CDB error: a zone management command was
                 * attempted on a conventional zone. Nothing to worry about,
                 * so be quiet about the error.
                 */
                rq->rq_flags |= RQF_QUIET;
        } else if (sd_zbc_need_zone_wp_update(rq))
                good_bytes = sd_zbc_zone_wp_update(cmd, good_bytes);

        if (req_op(rq) == REQ_OP_ZONE_APPEND)
                blk_req_zone_write_unlock(rq);

        return good_bytes;
}

/**
 * sd_zbc_check_zoned_characteristics - Check zoned block device characteristics
 * @sdkp: Target disk
 * @buf: Buffer where to store the VPD page data
 *
 * Read VPD page B6, get information and check that reads are unconstrained.
 */
static int sd_zbc_check_zoned_characteristics(struct scsi_disk *sdkp,
                                              unsigned char *buf)
{

        if (scsi_get_vpd_page(sdkp->device, 0xb6, buf, 64)) {
                sd_printk(KERN_NOTICE, sdkp,
                          "Read zoned characteristics VPD page failed\n");
                return -ENODEV;
        }

        if (sdkp->device->type != TYPE_ZBC) {
                /* Host-aware */
                sdkp->urswrz = 1;
                sdkp->zones_optimal_open = get_unaligned_be32(&buf[8]);
                sdkp->zones_optimal_nonseq = get_unaligned_be32(&buf[12]);
                sdkp->zones_max_open = 0;
        } else {
                /* Host-managed */
                sdkp->urswrz = buf[4] & 1;
                sdkp->zones_optimal_open = 0;
                sdkp->zones_optimal_nonseq = 0;
                sdkp->zones_max_open = get_unaligned_be32(&buf[16]);
        }

        /*
         * Check for unconstrained reads: host-managed devices with
         * constrained reads (drives failing read after write pointer)
         * are not supported.
         */
        if (!sdkp->urswrz) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                          "constrained reads devices are not supported\n");
                return -ENODEV;
        }

        return 0;
}

/**
 * sd_zbc_check_capacity - Check the device capacity
 * @sdkp: Target disk
 * @buf: command buffer
 * @zblocks: zone size in number of blocks
 *
 * Get the device zone size and check that the device capacity as reported
 * by READ CAPACITY matches the max_lba value (plus one) of the report zones
 * command reply for devices with RC_BASIS == 0.
 *
 * Returns 0 upon success or an error code upon failure.
 */
static int sd_zbc_check_capacity(struct scsi_disk *sdkp, unsigned char *buf,
                                 u32 *zblocks)
{
        u64 zone_blocks;
        sector_t max_lba;
        unsigned char *rec;
        int ret;

        /* Do a report zone to get max_lba and the size of the first zone */
        ret = sd_zbc_do_report_zones(sdkp, buf, SD_BUF_SIZE, 0, false);
        if (ret)
                return ret;

        if (sdkp->rc_basis == 0) {
                /* The max_lba field is the capacity of this device */
                max_lba = get_unaligned_be64(&buf[8]);
                if (sdkp->capacity != max_lba + 1) {
                        if (sdkp->first_scan)
                                sd_printk(KERN_WARNING, sdkp,
                                        "Changing capacity from %llu to max LBA+1 %llu\n",
                                        (unsigned long long)sdkp->capacity,
                                        (unsigned long long)max_lba + 1);
                        sdkp->capacity = max_lba + 1;
                }
        }

        /* Get the size of the first reported zone */
        rec = buf + 64;
        zone_blocks = get_unaligned_be64(&rec[8]);
        if (logical_to_sectors(sdkp->device, zone_blocks) > UINT_MAX) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Zone size too large\n");
                return -EFBIG;
        }

        *zblocks = zone_blocks;

        return 0;
}

static void sd_zbc_print_zones(struct scsi_disk *sdkp)
{
        if (!sd_is_zoned(sdkp) || !sdkp->capacity)
                return;

        if (sdkp->capacity & (sdkp->zone_blocks - 1))
                sd_printk(KERN_NOTICE, sdkp,
                          "%u zones of %u logical blocks + 1 runt zone\n",
                          sdkp->nr_zones - 1,
                          sdkp->zone_blocks);
        else
                sd_printk(KERN_NOTICE, sdkp,
                          "%u zones of %u logical blocks\n",
                          sdkp->nr_zones,
                          sdkp->zone_blocks);
}

static int sd_zbc_init_disk(struct scsi_disk *sdkp)
{
        sdkp->zones_wp_offset = NULL;
        spin_lock_init(&sdkp->zones_wp_offset_lock);
        sdkp->rev_wp_offset = NULL;
        mutex_init(&sdkp->rev_mutex);
        INIT_WORK(&sdkp->zone_wp_offset_work, sd_zbc_update_wp_offset_workfn);
        sdkp->zone_wp_update_buf = kzalloc(SD_BUF_SIZE, GFP_KERNEL);
        if (!sdkp->zone_wp_update_buf)
                return -ENOMEM;

        return 0;
}

void sd_zbc_release_disk(struct scsi_disk *sdkp)
{
        kvfree(sdkp->zones_wp_offset);
        sdkp->zones_wp_offset = NULL;
        kfree(sdkp->zone_wp_update_buf);
        sdkp->zone_wp_update_buf = NULL;
}

static void sd_zbc_revalidate_zones_cb(struct gendisk *disk)
{
        struct scsi_disk *sdkp = scsi_disk(disk);

        swap(sdkp->zones_wp_offset, sdkp->rev_wp_offset);
}

int sd_zbc_revalidate_zones(struct scsi_disk *sdkp)
{
        struct gendisk *disk = sdkp->disk;
        struct request_queue *q = disk->queue;
        u32 zone_blocks = sdkp->rev_zone_blocks;
        unsigned int nr_zones = sdkp->rev_nr_zones;
        u32 max_append;
        int ret = 0;

        /*
         * For all zoned disks, initialize zone append emulation data if not
         * already done. This is necessary also for host-aware disks used as
         * regular disks due to the presence of partitions as these partitions
         * may be deleted and the disk zoned model changed back from
         * BLK_ZONED_NONE to BLK_ZONED_HA.
         */
        if (sd_is_zoned(sdkp) && !sdkp->zone_wp_update_buf) {
                ret = sd_zbc_init_disk(sdkp);
                if (ret)
                        return ret;
        }

        /*
         * There is nothing to do for regular disks, including host-aware disks
         * that have partitions.
         */
        if (!blk_queue_is_zoned(q))
                return 0;

        /*
         * Make sure revalidate zones are serialized to ensure exclusive
         * updates of the scsi disk data.
         */
        mutex_lock(&sdkp->rev_mutex);

        if (sdkp->zone_blocks == zone_blocks &&
            sdkp->nr_zones == nr_zones &&
            disk->queue->nr_zones == nr_zones)
                goto unlock;

        sdkp->zone_blocks = zone_blocks;
        sdkp->nr_zones = nr_zones;
        sdkp->rev_wp_offset = kvcalloc(nr_zones, sizeof(u32), GFP_NOIO);
        if (!sdkp->rev_wp_offset) {
                ret = -ENOMEM;
                goto unlock;
        }

        ret = blk_revalidate_disk_zones(disk, sd_zbc_revalidate_zones_cb);

        kvfree(sdkp->rev_wp_offset);
        sdkp->rev_wp_offset = NULL;

        if (ret) {
                sdkp->zone_blocks = 0;
                sdkp->nr_zones = 0;
                sdkp->capacity = 0;
                goto unlock;
        }

        max_append = min_t(u32, logical_to_sectors(sdkp->device, zone_blocks),
                           q->limits.max_segments << (PAGE_SHIFT - 9));
        max_append = min_t(u32, max_append, queue_max_hw_sectors(q));

        blk_queue_max_zone_append_sectors(q, max_append);

        sd_zbc_print_zones(sdkp);

unlock:
        mutex_unlock(&sdkp->rev_mutex);

        return ret;
}

int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
{
        struct gendisk *disk = sdkp->disk;
        struct request_queue *q = disk->queue;
        unsigned int nr_zones;
        u32 zone_blocks = 0;
        int ret;

        if (!sd_is_zoned(sdkp))
                /*
                 * Device managed or normal SCSI disk,
                 * no special handling required
                 */
                return 0;

        /* Check zoned block device characteristics (unconstrained reads) */
        ret = sd_zbc_check_zoned_characteristics(sdkp, buf);
        if (ret)
                goto err;

        /* Check the device capacity reported by report zones */
        ret = sd_zbc_check_capacity(sdkp, buf, &zone_blocks);
        if (ret != 0)
                goto err;

        /* The drive satisfies the kernel restrictions: set it up */
        blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
        blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
        if (sdkp->zones_max_open == U32_MAX)
                blk_queue_max_open_zones(q, 0);
        else
                blk_queue_max_open_zones(q, sdkp->zones_max_open);
        blk_queue_max_active_zones(q, 0);
        nr_zones = round_up(sdkp->capacity, zone_blocks) >> ilog2(zone_blocks);

        /* READ16/WRITE16 is mandatory for ZBC disks */
        sdkp->device->use_16_for_rw = 1;
        sdkp->device->use_10_for_rw = 0;

        sdkp->rev_nr_zones = nr_zones;
        sdkp->rev_zone_blocks = zone_blocks;

        return 0;

err:
        sdkp->capacity = 0;

        return ret;
}