// SPDX-License-Identifier: GPL-2.0-only
//#define DEBUG
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#include <linux/string_helpers.h>
#include <linux/idr.h>
#include <linux/blk-mq.h>
#include <linux/numa.h>
#include <linux/vmalloc.h>
#include <uapi/linux/virtio_ring.h>

#define PART_BITS 4
#define VQ_NAME_LEN 16
#define MAX_DISCARD_SEGMENTS 256u

/* The maximum number of sg elements that fit into a virtqueue */
#define VIRTIO_BLK_MAX_SG_ELEMS 32768

#ifdef CONFIG_ARCH_NO_SG_CHAIN
#define VIRTIO_BLK_INLINE_SG_CNT        0
#else
#define VIRTIO_BLK_INLINE_SG_CNT        2
#endif

static unsigned int num_request_queues;
module_param(num_request_queues, uint, 0644);
MODULE_PARM_DESC(num_request_queues,
                 "Limit the number of request queues to use for blk device. "
                 "0 for no limit. "
                 "Values > nr_cpu_ids truncated to nr_cpu_ids.");

static unsigned int poll_queues;
module_param(poll_queues, uint, 0644);
MODULE_PARM_DESC(poll_queues, "The number of dedicated virtqueues for polling I/O");

static int major;
static DEFINE_IDA(vd_index_ida);

static struct workqueue_struct *virtblk_wq;

struct virtio_blk_vq {
        struct virtqueue *vq;
        spinlock_t lock;
        char name[VQ_NAME_LEN];
} ____cacheline_aligned_in_smp;

struct virtio_blk {
        /*
         * This mutex must be held by anything that may run after
         * virtblk_remove() sets vblk->vdev to NULL.
         *
         * blk-mq, virtqueue processing, and sysfs attribute code paths are
         * shut down before vblk->vdev is set to NULL and therefore do not need
         * to hold this mutex.
         */
        struct mutex vdev_mutex;
        struct virtio_device *vdev;

        /* The disk structure for the kernel. */
        struct gendisk *disk;

        /* Block layer tags. */
        struct blk_mq_tag_set tag_set;

        /* Process context for config space updates */
        struct work_struct config_work;

        /* Ida index - used to track minor number allocations. */
        int index;

        /* num of vqs */
        int num_vqs;
        int io_queues[HCTX_MAX_TYPES];
        struct virtio_blk_vq *vqs;

        /* For zoned device */
        unsigned int zone_sectors;
};

struct virtblk_req {
        /* Out header */
        struct virtio_blk_outhdr out_hdr;

        /* In header */
        union {
                u8 status;

                /*
                 * The zone append command has an extended in header.
                 * The status field in zone_append_in_hdr must always
                 * be the last byte.
                 */
                struct {
                        __virtio64 sector;
                        u8 status;
                } zone_append;
        } in_hdr;

        size_t in_hdr_len;

        struct sg_table sg_table;
        struct scatterlist sg[];
};

static inline blk_status_t virtblk_result(u8 status)
{
        switch (status) {
        case VIRTIO_BLK_S_OK:
                return BLK_STS_OK;
        case VIRTIO_BLK_S_UNSUPP:
                return BLK_STS_NOTSUPP;
        case VIRTIO_BLK_S_ZONE_OPEN_RESOURCE:
                return BLK_STS_ZONE_OPEN_RESOURCE;
        case VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE:
                return BLK_STS_ZONE_ACTIVE_RESOURCE;
        case VIRTIO_BLK_S_IOERR:
        case VIRTIO_BLK_S_ZONE_UNALIGNED_WP:
        default:
                return BLK_STS_IOERR;
        }
}

static inline struct virtio_blk_vq *get_virtio_blk_vq(struct blk_mq_hw_ctx *hctx)
{
        struct virtio_blk *vblk = hctx->queue->queuedata;
        struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];

        return vq;
}

static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr)
{
        struct scatterlist out_hdr, in_hdr, *sgs[3];
        unsigned int num_out = 0, num_in = 0;

        sg_init_one(&out_hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
        sgs[num_out++] = &out_hdr;

        if (vbr->sg_table.nents) {
                if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
                        sgs[num_out++] = vbr->sg_table.sgl;
                else
                        sgs[num_out + num_in++] = vbr->sg_table.sgl;
        }

        sg_init_one(&in_hdr, &vbr->in_hdr.status, vbr->in_hdr_len);
        sgs[num_out + num_in++] = &in_hdr;

        return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
}

static int virtblk_setup_discard_write_zeroes_erase(struct request *req, bool unmap)
{
        unsigned short segments = blk_rq_nr_discard_segments(req);
        unsigned short n = 0;
        struct virtio_blk_discard_write_zeroes *range;
        struct bio *bio;
        u32 flags = 0;

        if (unmap)
                flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;

        range = kmalloc_objs(*range, segments, GFP_ATOMIC);
        if (!range)
                return -ENOMEM;

        /*
         * Single max discard segment means multi-range discard isn't
         * supported, and block layer only runs contiguity merge like
         * normal RW request. So we can't reply on bio for retrieving
         * each range info.
         */
        if (queue_max_discard_segments(req->q) == 1) {
                range[0].flags = cpu_to_le32(flags);
                range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req));
                range[0].sector = cpu_to_le64(blk_rq_pos(req));
                n = 1;
        } else {
                __rq_for_each_bio(bio, req) {
                        u64 sector = bio->bi_iter.bi_sector;
                        u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;

                        range[n].flags = cpu_to_le32(flags);
                        range[n].num_sectors = cpu_to_le32(num_sectors);
                        range[n].sector = cpu_to_le64(sector);
                        n++;
                }
        }

        WARN_ON_ONCE(n != segments);

        bvec_set_virt(&req->special_vec, range, sizeof(*range) * segments);
        req->rq_flags |= RQF_SPECIAL_PAYLOAD;

        return 0;
}

static void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr)
{
        if (blk_rq_nr_phys_segments(req))
                sg_free_table_chained(&vbr->sg_table,
                                      VIRTIO_BLK_INLINE_SG_CNT);
}

static int virtblk_map_data(struct blk_mq_hw_ctx *hctx, struct request *req,
                struct virtblk_req *vbr)
{
        int err;

        if (!blk_rq_nr_phys_segments(req))
                return 0;

        vbr->sg_table.sgl = vbr->sg;
        err = sg_alloc_table_chained(&vbr->sg_table,
                                     blk_rq_nr_phys_segments(req),
                                     vbr->sg_table.sgl,
                                     VIRTIO_BLK_INLINE_SG_CNT);
        if (unlikely(err))
                return -ENOMEM;

        return blk_rq_map_sg(req, vbr->sg_table.sgl);
}

static void virtblk_cleanup_cmd(struct request *req)
{
        if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
                kfree(bvec_virt(&req->special_vec));
}

static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
                                      struct request *req,
                                      struct virtblk_req *vbr)
{
        size_t in_hdr_len = sizeof(vbr->in_hdr.status);
        bool unmap = false;
        u32 type;
        u64 sector = 0;

        if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) && op_is_zone_mgmt(req_op(req)))
                return BLK_STS_NOTSUPP;

        /* Set fields for all request types */
        vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));

        switch (req_op(req)) {
        case REQ_OP_READ:
                type = VIRTIO_BLK_T_IN;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_WRITE:
                type = VIRTIO_BLK_T_OUT;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_FLUSH:
                type = VIRTIO_BLK_T_FLUSH;
                break;
        case REQ_OP_DISCARD:
                type = VIRTIO_BLK_T_DISCARD;
                break;
        case REQ_OP_WRITE_ZEROES:
                type = VIRTIO_BLK_T_WRITE_ZEROES;
                unmap = !(req->cmd_flags & REQ_NOUNMAP);
                break;
        case REQ_OP_SECURE_ERASE:
                type = VIRTIO_BLK_T_SECURE_ERASE;
                break;
        case REQ_OP_ZONE_OPEN:
                type = VIRTIO_BLK_T_ZONE_OPEN;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_ZONE_CLOSE:
                type = VIRTIO_BLK_T_ZONE_CLOSE;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_ZONE_FINISH:
                type = VIRTIO_BLK_T_ZONE_FINISH;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_ZONE_APPEND:
                type = VIRTIO_BLK_T_ZONE_APPEND;
                sector = blk_rq_pos(req);
                in_hdr_len = sizeof(vbr->in_hdr.zone_append);
                break;
        case REQ_OP_ZONE_RESET:
                type = VIRTIO_BLK_T_ZONE_RESET;
                sector = blk_rq_pos(req);
                break;
        case REQ_OP_ZONE_RESET_ALL:
                type = VIRTIO_BLK_T_ZONE_RESET_ALL;
                break;
        case REQ_OP_DRV_IN:
                /*
                 * Out header has already been prepared by the caller (virtblk_get_id()
                 * or virtblk_submit_zone_report()), nothing to do here.
                 */
                return 0;
        default:
                WARN_ON_ONCE(1);
                return BLK_STS_IOERR;
        }

        /* Set fields for non-REQ_OP_DRV_IN request types */
        vbr->in_hdr_len = in_hdr_len;
        vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
        vbr->out_hdr.sector = cpu_to_virtio64(vdev, sector);

        if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES ||
            type == VIRTIO_BLK_T_SECURE_ERASE) {
                if (virtblk_setup_discard_write_zeroes_erase(req, unmap))
                        return BLK_STS_RESOURCE;
        }

        return 0;
}

/*
 * The status byte is always the last byte of the virtblk request
 * in-header. This helper fetches its value for all in-header formats
 * that are currently defined.
 */
static inline u8 virtblk_vbr_status(struct virtblk_req *vbr)
{
        return *((u8 *)&vbr->in_hdr + vbr->in_hdr_len - 1);
}

static inline void virtblk_request_done(struct request *req)
{
        struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
        blk_status_t status = virtblk_result(virtblk_vbr_status(vbr));
        struct virtio_blk *vblk = req->mq_hctx->queue->queuedata;

        virtblk_unmap_data(req, vbr);
        virtblk_cleanup_cmd(req);

        if (req_op(req) == REQ_OP_ZONE_APPEND)
                req->__sector = virtio64_to_cpu(vblk->vdev,
                                                vbr->in_hdr.zone_append.sector);

        blk_mq_end_request(req, status);
}

static void virtblk_done(struct virtqueue *vq)
{
        struct virtio_blk *vblk = vq->vdev->priv;
        bool req_done = false;
        int qid = vq->index;
        struct virtblk_req *vbr;
        unsigned long flags;
        unsigned int len;

        spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
        do {
                virtqueue_disable_cb(vq);
                while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
                        struct request *req = blk_mq_rq_from_pdu(vbr);

                        if (likely(!blk_should_fake_timeout(req->q)))
                                blk_mq_complete_request(req);
                        req_done = true;
                }
        } while (!virtqueue_enable_cb(vq));

        /* In case queue is stopped waiting for more buffers. */
        if (req_done)
                blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
        spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
}

static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
{
        struct virtio_blk *vblk = hctx->queue->queuedata;
        struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
        bool kick;

        spin_lock_irq(&vq->lock);
        kick = virtqueue_kick_prepare(vq->vq);
        spin_unlock_irq(&vq->lock);

        if (kick)
                virtqueue_notify(vq->vq);
}

static blk_status_t virtblk_fail_to_queue(struct request *req, int rc)
{
        virtblk_cleanup_cmd(req);
        switch (rc) {
        case -ENOSPC:
                return BLK_STS_DEV_RESOURCE;
        case -ENOMEM:
                return BLK_STS_RESOURCE;
        default:
                return BLK_STS_IOERR;
        }
}

static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx,
                                        struct virtio_blk *vblk,
                                        struct request *req,
                                        struct virtblk_req *vbr)
{
        blk_status_t status;
        int num;

        status = virtblk_setup_cmd(vblk->vdev, req, vbr);
        if (unlikely(status))
                return status;

        num = virtblk_map_data(hctx, req, vbr);
        if (unlikely(num < 0))
                return virtblk_fail_to_queue(req, -ENOMEM);
        vbr->sg_table.nents = num;

        blk_mq_start_request(req);

        return BLK_STS_OK;
}

static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
                           const struct blk_mq_queue_data *bd)
{
        struct virtio_blk *vblk = hctx->queue->queuedata;
        struct request *req = bd->rq;
        struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
        unsigned long flags;
        int qid = hctx->queue_num;
        bool notify = false;
        blk_status_t status;
        int err;

        status = virtblk_prep_rq(hctx, vblk, req, vbr);
        if (unlikely(status))
                return status;

        spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
        err = virtblk_add_req(vblk->vqs[qid].vq, vbr);
        if (err) {
                virtqueue_kick(vblk->vqs[qid].vq);
                /* Don't stop the queue if -ENOMEM: we may have failed to
                 * bounce the buffer due to global resource outage.
                 */
                if (err == -ENOSPC)
                        blk_mq_stop_hw_queue(hctx);
                spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
                virtblk_unmap_data(req, vbr);
                return virtblk_fail_to_queue(req, err);
        }

        if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
                notify = true;
        spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);

        if (notify)
                virtqueue_notify(vblk->vqs[qid].vq);
        return BLK_STS_OK;
}

static bool virtblk_prep_rq_batch(struct request *req)
{
        struct virtio_blk *vblk = req->mq_hctx->queue->queuedata;
        struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);

        return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK;
}

static void virtblk_add_req_batch(struct virtio_blk_vq *vq,
                struct rq_list *rqlist)
{
        struct request *req;
        unsigned long flags;
        bool kick;

        spin_lock_irqsave(&vq->lock, flags);

        while ((req = rq_list_pop(rqlist))) {
                struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
                int err;

                err = virtblk_add_req(vq->vq, vbr);
                if (err) {
                        virtblk_unmap_data(req, vbr);
                        virtblk_cleanup_cmd(req);
                        blk_mq_requeue_request(req, true);
                }
        }

        kick = virtqueue_kick_prepare(vq->vq);
        spin_unlock_irqrestore(&vq->lock, flags);

        if (kick)
                virtqueue_notify(vq->vq);
}

static void virtio_queue_rqs(struct rq_list *rqlist)
{
        struct rq_list submit_list = { };
        struct rq_list requeue_list = { };
        struct virtio_blk_vq *vq = NULL;
        struct request *req;

        while ((req = rq_list_pop(rqlist))) {
                struct virtio_blk_vq *this_vq = get_virtio_blk_vq(req->mq_hctx);

                if (vq && vq != this_vq)
                        virtblk_add_req_batch(vq, &submit_list);
                vq = this_vq;

                if (virtblk_prep_rq_batch(req))
                        rq_list_add_tail(&submit_list, req);
                else
                        rq_list_add_tail(&requeue_list, req);
        }

        if (vq)
                virtblk_add_req_batch(vq, &submit_list);
        *rqlist = requeue_list;
}

#ifdef CONFIG_BLK_DEV_ZONED
static void *virtblk_alloc_report_buffer(struct virtio_blk *vblk,
                                          unsigned int nr_zones,
                                          size_t *buflen)
{
        struct request_queue *q = vblk->disk->queue;
        size_t bufsize;
        void *buf;

        nr_zones = min_t(unsigned int, nr_zones,
                         get_capacity(vblk->disk) >> ilog2(vblk->zone_sectors));

        bufsize = sizeof(struct virtio_blk_zone_report) +
                nr_zones * sizeof(struct virtio_blk_zone_descriptor);
        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 >= sizeof(struct virtio_blk_zone_report)) {
                buf = __vmalloc(bufsize, GFP_KERNEL | __GFP_NORETRY);
                if (buf) {
                        *buflen = bufsize;
                        return buf;
                }
                bufsize >>= 1;
        }

        return NULL;
}

static int virtblk_submit_zone_report(struct virtio_blk *vblk,
                                       char *report_buf, size_t report_len,
                                       sector_t sector)
{
        struct request_queue *q = vblk->disk->queue;
        struct request *req;
        struct virtblk_req *vbr;
        int err;

        req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
        if (IS_ERR(req))
                return PTR_ERR(req);

        vbr = blk_mq_rq_to_pdu(req);
        vbr->in_hdr_len = sizeof(vbr->in_hdr.status);
        vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_ZONE_REPORT);
        vbr->out_hdr.sector = cpu_to_virtio64(vblk->vdev, sector);

        err = blk_rq_map_kern(req, report_buf, report_len, GFP_KERNEL);
        if (err)
                goto out;

        blk_execute_rq(req, false);
        err = blk_status_to_errno(virtblk_result(vbr->in_hdr.status));
out:
        blk_mq_free_request(req);
        return err;
}

static int virtblk_parse_zone(struct virtio_blk *vblk,
                               struct virtio_blk_zone_descriptor *entry,
                               unsigned int idx,
                               struct blk_report_zones_args *args)
{
        struct blk_zone zone = { };

        zone.start = virtio64_to_cpu(vblk->vdev, entry->z_start);
        if (zone.start + vblk->zone_sectors <= get_capacity(vblk->disk))
                zone.len = vblk->zone_sectors;
        else
                zone.len = get_capacity(vblk->disk) - zone.start;
        zone.capacity = virtio64_to_cpu(vblk->vdev, entry->z_cap);
        zone.wp = virtio64_to_cpu(vblk->vdev, entry->z_wp);

        switch (entry->z_type) {
        case VIRTIO_BLK_ZT_SWR:
                zone.type = BLK_ZONE_TYPE_SEQWRITE_REQ;
                break;
        case VIRTIO_BLK_ZT_SWP:
                zone.type = BLK_ZONE_TYPE_SEQWRITE_PREF;
                break;
        case VIRTIO_BLK_ZT_CONV:
                zone.type = BLK_ZONE_TYPE_CONVENTIONAL;
                break;
        default:
                dev_err(&vblk->vdev->dev, "zone %llu: invalid type %#x\n",
                        zone.start, entry->z_type);
                return -EIO;
        }

        switch (entry->z_state) {
        case VIRTIO_BLK_ZS_EMPTY:
                zone.cond = BLK_ZONE_COND_EMPTY;
                break;
        case VIRTIO_BLK_ZS_CLOSED:
                zone.cond = BLK_ZONE_COND_CLOSED;
                break;
        case VIRTIO_BLK_ZS_FULL:
                zone.cond = BLK_ZONE_COND_FULL;
                zone.wp = zone.start + zone.len;
                break;
        case VIRTIO_BLK_ZS_EOPEN:
                zone.cond = BLK_ZONE_COND_EXP_OPEN;
                break;
        case VIRTIO_BLK_ZS_IOPEN:
                zone.cond = BLK_ZONE_COND_IMP_OPEN;
                break;
        case VIRTIO_BLK_ZS_NOT_WP:
                zone.cond = BLK_ZONE_COND_NOT_WP;
                break;
        case VIRTIO_BLK_ZS_RDONLY:
                zone.cond = BLK_ZONE_COND_READONLY;
                zone.wp = ULONG_MAX;
                break;
        case VIRTIO_BLK_ZS_OFFLINE:
                zone.cond = BLK_ZONE_COND_OFFLINE;
                zone.wp = ULONG_MAX;
                break;
        default:
                dev_err(&vblk->vdev->dev, "zone %llu: invalid condition %#x\n",
                        zone.start, entry->z_state);
                return -EIO;
        }

        /*
         * The callback below checks the validity of the reported
         * entry data, no need to further validate it here.
         */
        return disk_report_zone(vblk->disk, &zone, idx, args);
}

static int virtblk_report_zones(struct gendisk *disk, sector_t sector,
                                 unsigned int nr_zones,
                                 struct blk_report_zones_args *args)
{
        struct virtio_blk *vblk = disk->private_data;
        struct virtio_blk_zone_report *report;
        unsigned long long nz, i;
        size_t buflen;
        unsigned int zone_idx = 0;
        int ret;

        if (WARN_ON_ONCE(!vblk->zone_sectors))
                return -EOPNOTSUPP;

        report = virtblk_alloc_report_buffer(vblk, nr_zones, &buflen);
        if (!report)
                return -ENOMEM;

        mutex_lock(&vblk->vdev_mutex);

        if (!vblk->vdev) {
                ret = -ENXIO;
                goto fail_report;
        }

        while (zone_idx < nr_zones && sector < get_capacity(vblk->disk)) {
                memset(report, 0, buflen);

                ret = virtblk_submit_zone_report(vblk, (char *)report,
                                                 buflen, sector);
                if (ret)
                        goto fail_report;

                nz = min_t(u64, virtio64_to_cpu(vblk->vdev, report->nr_zones),
                           nr_zones);
                if (!nz)
                        break;

                for (i = 0; i < nz && zone_idx < nr_zones; i++) {
                        ret = virtblk_parse_zone(vblk, &report->zones[i],
                                                 zone_idx, args);
                        if (ret)
                                goto fail_report;

                        sector = virtio64_to_cpu(vblk->vdev,
                                                 report->zones[i].z_start) +
                                 vblk->zone_sectors;
                        zone_idx++;
                }
        }

        if (zone_idx > 0)
                ret = zone_idx;
        else
                ret = -EINVAL;
fail_report:
        mutex_unlock(&vblk->vdev_mutex);
        kvfree(report);
        return ret;
}

static int virtblk_read_zoned_limits(struct virtio_blk *vblk,
                struct queue_limits *lim)
{
        struct virtio_device *vdev = vblk->vdev;
        u32 v, wg;

        dev_dbg(&vdev->dev, "probing host-managed zoned device\n");

        lim->features |= BLK_FEAT_ZONED;

        virtio_cread(vdev, struct virtio_blk_config,
                     zoned.max_open_zones, &v);
        lim->max_open_zones = v;
        dev_dbg(&vdev->dev, "max open zones = %u\n", v);

        virtio_cread(vdev, struct virtio_blk_config,
                     zoned.max_active_zones, &v);
        lim->max_active_zones = v;
        dev_dbg(&vdev->dev, "max active zones = %u\n", v);

        virtio_cread(vdev, struct virtio_blk_config,
                     zoned.write_granularity, &wg);
        if (!wg) {
                dev_warn(&vdev->dev, "zero write granularity reported\n");
                return -ENODEV;
        }
        lim->physical_block_size = wg;
        lim->io_min = wg;

        dev_dbg(&vdev->dev, "write granularity = %u\n", wg);

        /*
         * virtio ZBD specification doesn't require zones to be a power of
         * two sectors in size, but the code in this driver expects that.
         */
        virtio_cread(vdev, struct virtio_blk_config, zoned.zone_sectors,
                     &vblk->zone_sectors);
        if (vblk->zone_sectors == 0 || !is_power_of_2(vblk->zone_sectors)) {
                dev_err(&vdev->dev,
                        "zoned device with non power of two zone size %u\n",
                        vblk->zone_sectors);
                return -ENODEV;
        }
        lim->chunk_sectors = vblk->zone_sectors;
        dev_dbg(&vdev->dev, "zone sectors = %u\n", vblk->zone_sectors);

        if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
                dev_warn(&vblk->vdev->dev,
                         "ignoring negotiated F_DISCARD for zoned device\n");
                lim->max_hw_discard_sectors = 0;
        }

        virtio_cread(vdev, struct virtio_blk_config,
                     zoned.max_append_sectors, &v);
        if (!v) {
                dev_warn(&vdev->dev, "zero max_append_sectors reported\n");
                return -ENODEV;
        }
        if ((v << SECTOR_SHIFT) < wg) {
                dev_err(&vdev->dev,
                        "write granularity %u exceeds max_append_sectors %u limit\n",
                        wg, v);
                return -ENODEV;
        }
        lim->max_hw_zone_append_sectors = v;
        dev_dbg(&vdev->dev, "max append sectors = %u\n", v);

        return 0;
}
#else
/*
 * Zoned block device support is not configured in this kernel, host-managed
 * zoned devices can't be supported.
 */
#define virtblk_report_zones       NULL
static inline int virtblk_read_zoned_limits(struct virtio_blk *vblk,
                struct queue_limits *lim)
{
        dev_err(&vblk->vdev->dev,
                "virtio_blk: zoned devices are not supported");
        return -EOPNOTSUPP;
}
#endif /* CONFIG_BLK_DEV_ZONED */

/* return id (s/n) string for *disk to *id_str
 */
static int virtblk_get_id(struct gendisk *disk, char *id_str)
{
        struct virtio_blk *vblk = disk->private_data;
        struct request_queue *q = vblk->disk->queue;
        struct request *req;
        struct virtblk_req *vbr;
        int err;

        req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
        if (IS_ERR(req))
                return PTR_ERR(req);

        vbr = blk_mq_rq_to_pdu(req);
        vbr->in_hdr_len = sizeof(vbr->in_hdr.status);
        vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_GET_ID);
        vbr->out_hdr.sector = 0;

        err = blk_rq_map_kern(req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
        if (err)
                goto out;

        blk_execute_rq(req, false);
        err = blk_status_to_errno(virtblk_result(vbr->in_hdr.status));
out:
        blk_mq_free_request(req);
        return err;
}

/* We provide getgeo only to please some old bootloader/partitioning tools */
static int virtblk_getgeo(struct gendisk *disk, struct hd_geometry *geo)
{
        struct virtio_blk *vblk = disk->private_data;
        int ret = 0;

        mutex_lock(&vblk->vdev_mutex);

        if (!vblk->vdev) {
                ret = -ENXIO;
                goto out;
        }

        /* see if the host passed in geometry config */
        if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
                virtio_cread(vblk->vdev, struct virtio_blk_config,
                             geometry.cylinders, &geo->cylinders);
                virtio_cread(vblk->vdev, struct virtio_blk_config,
                             geometry.heads, &geo->heads);
                virtio_cread(vblk->vdev, struct virtio_blk_config,
                             geometry.sectors, &geo->sectors);
        } else {
                /* some standard values, similar to sd */
                geo->heads = 1 << 6;
                geo->sectors = 1 << 5;
                geo->cylinders = get_capacity(disk) >> 11;
        }
out:
        mutex_unlock(&vblk->vdev_mutex);
        return ret;
}

static void virtblk_free_disk(struct gendisk *disk)
{
        struct virtio_blk *vblk = disk->private_data;

        ida_free(&vd_index_ida, vblk->index);
        mutex_destroy(&vblk->vdev_mutex);
        kfree(vblk);
}

static const struct block_device_operations virtblk_fops = {
        .owner          = THIS_MODULE,
        .getgeo         = virtblk_getgeo,
        .free_disk      = virtblk_free_disk,
        .report_zones   = virtblk_report_zones,
};

static int index_to_minor(int index)
{
        return index << PART_BITS;
}

static int minor_to_index(int minor)
{
        return minor >> PART_BITS;
}

static ssize_t serial_show(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct gendisk *disk = dev_to_disk(dev);
        int err;

        /* sysfs gives us a PAGE_SIZE buffer */
        BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);

        buf[VIRTIO_BLK_ID_BYTES] = '\0';
        err = virtblk_get_id(disk, buf);
        if (!err)
                return strlen(buf);

        if (err == -EIO) /* Unsupported? Make it empty. */
                return 0;

        return err;
}

static DEVICE_ATTR_RO(serial);

/* The queue's logical block size must be set before calling this */
static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
{
        struct virtio_device *vdev = vblk->vdev;
        struct request_queue *q = vblk->disk->queue;
        char cap_str_2[10], cap_str_10[10];
        unsigned long long nblocks;
        u64 capacity;

        /* Host must always specify the capacity. */
        virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);

        nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);

        string_get_size(nblocks, queue_logical_block_size(q),
                        STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
        string_get_size(nblocks, queue_logical_block_size(q),
                        STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));

        dev_notice(&vdev->dev,
                   "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
                   vblk->disk->disk_name,
                   resize ? "new size: " : "",
                   nblocks,
                   queue_logical_block_size(q),
                   cap_str_10,
                   cap_str_2);

        set_capacity_and_notify(vblk->disk, capacity);
}

static void virtblk_config_changed_work(struct work_struct *work)
{
        struct virtio_blk *vblk =
                container_of(work, struct virtio_blk, config_work);

        virtblk_update_capacity(vblk, true);
}

static void virtblk_config_changed(struct virtio_device *vdev)
{
        struct virtio_blk *vblk = vdev->priv;

        queue_work(virtblk_wq, &vblk->config_work);
}

static int init_vq(struct virtio_blk *vblk)
{
        int err;
        unsigned short i;
        struct virtqueue_info *vqs_info;
        struct virtqueue **vqs;
        unsigned short num_vqs;
        unsigned short num_poll_vqs;
        struct virtio_device *vdev = vblk->vdev;
        struct irq_affinity desc = { 0, };

        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
                                   struct virtio_blk_config, num_queues,
                                   &num_vqs);
        if (err)
                num_vqs = 1;

        if (!err && !num_vqs) {
                dev_err(&vdev->dev, "MQ advertised but zero queues reported\n");
                return -EINVAL;
        }

        num_vqs = blk_mq_num_possible_queues(
                        min_not_zero(num_request_queues, num_vqs));

        num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1);

        vblk->io_queues[HCTX_TYPE_DEFAULT] = num_vqs - num_poll_vqs;
        vblk->io_queues[HCTX_TYPE_READ] = 0;
        vblk->io_queues[HCTX_TYPE_POLL] = num_poll_vqs;

        dev_info(&vdev->dev, "%d/%d/%d default/read/poll queues\n",
                                vblk->io_queues[HCTX_TYPE_DEFAULT],
                                vblk->io_queues[HCTX_TYPE_READ],
                                vblk->io_queues[HCTX_TYPE_POLL]);

        vblk->vqs = kmalloc_objs(*vblk->vqs, num_vqs);
        if (!vblk->vqs)
                return -ENOMEM;

        vqs_info = kzalloc_objs(*vqs_info, num_vqs);
        vqs = kmalloc_objs(*vqs, num_vqs);
        if (!vqs_info || !vqs) {
                err = -ENOMEM;
                goto out;
        }

        for (i = 0; i < num_vqs - num_poll_vqs; i++) {
                vqs_info[i].callback = virtblk_done;
                snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%u", i);
                vqs_info[i].name = vblk->vqs[i].name;
        }

        for (; i < num_vqs; i++) {
                snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req_poll.%u", i);
                vqs_info[i].name = vblk->vqs[i].name;
        }

        /* Discover virtqueues and write information to configuration.  */
        err = virtio_find_vqs(vdev, num_vqs, vqs, vqs_info, &desc);
        if (err)
                goto out;

        for (i = 0; i < num_vqs; i++) {
                spin_lock_init(&vblk->vqs[i].lock);
                vblk->vqs[i].vq = vqs[i];
        }
        vblk->num_vqs = num_vqs;

out:
        kfree(vqs);
        kfree(vqs_info);
        if (err) {
                kfree(vblk->vqs);
                /*
                 * Set to NULL to prevent freeing vqs again during freezing.
                 */
                vblk->vqs = NULL;
        }
        return err;
}

/*
 * Legacy naming scheme used for virtio devices.  We are stuck with it for
 * virtio blk but don't ever use it for any new driver.
 */
static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
{
        const int base = 'z' - 'a' + 1;
        char *begin = buf + strlen(prefix);
        char *end = buf + buflen;
        char *p;
        int unit;

        p = end - 1;
        *p = '\0';
        unit = base;
        do {
                if (p == begin)
                        return -EINVAL;
                *--p = 'a' + (index % unit);
                index = (index / unit) - 1;
        } while (index >= 0);

        memmove(begin, p, end - p);
        memcpy(buf, prefix, strlen(prefix));

        return 0;
}

static int virtblk_get_cache_mode(struct virtio_device *vdev)
{
        u8 writeback;
        int err;

        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
                                   struct virtio_blk_config, wce,
                                   &writeback);

        /*
         * If WCE is not configurable and flush is not available,
         * assume no writeback cache is in use.
         */
        if (err)
                writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);

        return writeback;
}

static const char *const virtblk_cache_types[] = {
        "write through", "write back"
};

static ssize_t
cache_type_store(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t count)
{
        struct gendisk *disk = dev_to_disk(dev);
        struct virtio_blk *vblk = disk->private_data;
        struct virtio_device *vdev = vblk->vdev;
        struct queue_limits lim;
        int i;

        BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
        i = sysfs_match_string(virtblk_cache_types, buf);
        if (i < 0)
                return i;

        virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);

        lim = queue_limits_start_update(disk->queue);
        if (virtblk_get_cache_mode(vdev))
                lim.features |= BLK_FEAT_WRITE_CACHE;
        else
                lim.features &= ~BLK_FEAT_WRITE_CACHE;
        i = queue_limits_commit_update_frozen(disk->queue, &lim);
        if (i)
                return i;
        return count;
}

static ssize_t
cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct gendisk *disk = dev_to_disk(dev);
        struct virtio_blk *vblk = disk->private_data;
        u8 writeback = virtblk_get_cache_mode(vblk->vdev);

        BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
        return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
}

static DEVICE_ATTR_RW(cache_type);

static struct attribute *virtblk_attrs[] = {
        &dev_attr_serial.attr,
        &dev_attr_cache_type.attr,
        NULL,
};

static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
                struct attribute *a, int n)
{
        struct device *dev = kobj_to_dev(kobj);
        struct gendisk *disk = dev_to_disk(dev);
        struct virtio_blk *vblk = disk->private_data;
        struct virtio_device *vdev = vblk->vdev;

        if (a == &dev_attr_cache_type.attr &&
            !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
                return S_IRUGO;

        return a->mode;
}

static const struct attribute_group virtblk_attr_group = {
        .attrs = virtblk_attrs,
        .is_visible = virtblk_attrs_are_visible,
};

static const struct attribute_group *virtblk_attr_groups[] = {
        &virtblk_attr_group,
        NULL,
};

static void virtblk_map_queues(struct blk_mq_tag_set *set)
{
        struct virtio_blk *vblk = set->driver_data;
        int i, qoff;

        for (i = 0, qoff = 0; i < set->nr_maps; i++) {
                struct blk_mq_queue_map *map = &set->map[i];

                map->nr_queues = vblk->io_queues[i];
                map->queue_offset = qoff;
                qoff += map->nr_queues;

                if (map->nr_queues == 0)
                        continue;

                /*
                 * Regular queues have interrupts and hence CPU affinity is
                 * defined by the core virtio code, but polling queues have
                 * no interrupts so we let the block layer assign CPU affinity.
                 */
                if (i == HCTX_TYPE_POLL)
                        blk_mq_map_queues(&set->map[i]);
                else
                        blk_mq_map_hw_queues(&set->map[i],
                                             &vblk->vdev->dev, 0);
        }
}

static void virtblk_complete_batch(struct io_comp_batch *iob)
{
        struct request *req;

        rq_list_for_each(&iob->req_list, req) {
                virtblk_unmap_data(req, blk_mq_rq_to_pdu(req));
                virtblk_cleanup_cmd(req);
        }
        blk_mq_end_request_batch(iob);
}

static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
{
        struct virtio_blk *vblk = hctx->queue->queuedata;
        struct virtio_blk_vq *vq = get_virtio_blk_vq(hctx);
        struct virtblk_req *vbr;
        unsigned long flags;
        unsigned int len;
        int found = 0;

        spin_lock_irqsave(&vq->lock, flags);

        while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) {
                struct request *req = blk_mq_rq_from_pdu(vbr);
                u8 status = virtblk_vbr_status(vbr);

                found++;
                if (!blk_mq_complete_request_remote(req) &&
                    !blk_mq_add_to_batch(req, iob, status != VIRTIO_BLK_S_OK,
                                         virtblk_complete_batch))
                        virtblk_request_done(req);
        }

        if (found)
                blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);

        spin_unlock_irqrestore(&vq->lock, flags);

        return found;
}

static const struct blk_mq_ops virtio_mq_ops = {
        .queue_rq       = virtio_queue_rq,
        .queue_rqs      = virtio_queue_rqs,
        .commit_rqs     = virtio_commit_rqs,
        .complete       = virtblk_request_done,
        .map_queues     = virtblk_map_queues,
        .poll           = virtblk_poll,
};

static unsigned int virtblk_queue_depth;
module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);

static int virtblk_read_limits(struct virtio_blk *vblk,
                struct queue_limits *lim)
{
        struct virtio_device *vdev = vblk->vdev;
        u32 v, max_size, sg_elems, opt_io_size;
        u32 max_discard_segs = 0;
        u32 discard_granularity = 0;
        u16 min_io_size;
        u8 physical_block_exp, alignment_offset;
        size_t max_dma_size;
        int err;

        /* We need to know how many segments before we allocate. */
        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
                                   struct virtio_blk_config, seg_max,
                                   &sg_elems);

        /* We need at least one SG element, whatever they say. */
        if (err || !sg_elems)
                sg_elems = 1;

        /* Prevent integer overflows and honor max vq size */
        sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);

        /* We can handle whatever the host told us to handle. */
        lim->max_segments = sg_elems;

        /* No real sector limit. */
        lim->max_hw_sectors = UINT_MAX;

        max_dma_size = virtio_max_dma_size(vdev);
        max_size = max_dma_size > U32_MAX ? U32_MAX : max_dma_size;

        /* Host can optionally specify maximum segment size and number of
         * segments. */
        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
                                   struct virtio_blk_config, size_max, &v);
        if (!err)
                max_size = min(max_size, v);

        lim->max_segment_size = max_size;

        /* Host can optionally specify the block size of the device */
        virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
                                   struct virtio_blk_config, blk_size,
                                   &lim->logical_block_size);

        /* Use topology information if available */
        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
                                   struct virtio_blk_config, physical_block_exp,
                                   &physical_block_exp);
        if (!err && physical_block_exp)
                lim->physical_block_size =
                        lim->logical_block_size * (1 << physical_block_exp);

        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
                                   struct virtio_blk_config, alignment_offset,
                                   &alignment_offset);
        if (!err && alignment_offset)
                lim->alignment_offset =
                        lim->logical_block_size * alignment_offset;

        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
                                   struct virtio_blk_config, min_io_size,
                                   &min_io_size);
        if (!err && min_io_size)
                lim->io_min = lim->logical_block_size * min_io_size;

        err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
                                   struct virtio_blk_config, opt_io_size,
                                   &opt_io_size);
        if (!err && opt_io_size)
                lim->io_opt = lim->logical_block_size * opt_io_size;

        if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
                virtio_cread(vdev, struct virtio_blk_config,
                             discard_sector_alignment, &discard_granularity);

                virtio_cread(vdev, struct virtio_blk_config,
                             max_discard_sectors, &v);
                lim->max_hw_discard_sectors = v ? v : UINT_MAX;

                virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
                             &max_discard_segs);
        }

        if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
                virtio_cread(vdev, struct virtio_blk_config,
                             max_write_zeroes_sectors, &v);
                lim->max_write_zeroes_sectors = v ? v : UINT_MAX;
        }

        /* The discard and secure erase limits are combined since the Linux
         * block layer uses the same limit for both commands.
         *
         * If both VIRTIO_BLK_F_SECURE_ERASE and VIRTIO_BLK_F_DISCARD features
         * are negotiated, we will use the minimum between the limits.
         *
         * discard sector alignment is set to the minimum between discard_sector_alignment
         * and secure_erase_sector_alignment.
         *
         * max discard sectors is set to the minimum between max_discard_seg and
         * max_secure_erase_seg.
         */
        if (virtio_has_feature(vdev, VIRTIO_BLK_F_SECURE_ERASE)) {

                virtio_cread(vdev, struct virtio_blk_config,
                             secure_erase_sector_alignment, &v);

                /* secure_erase_sector_alignment should not be zero, the device should set a
                 * valid number of sectors.
                 */
                if (!v) {
                        dev_err(&vdev->dev,
                                "virtio_blk: secure_erase_sector_alignment can't be 0\n");
                        return -EINVAL;
                }

                discard_granularity = min_not_zero(discard_granularity, v);

                virtio_cread(vdev, struct virtio_blk_config,
                             max_secure_erase_sectors, &v);

                /* max_secure_erase_sectors should not be zero, the device should set a
                 * valid number of sectors.
                 */
                if (!v) {
                        dev_err(&vdev->dev,
                                "virtio_blk: max_secure_erase_sectors can't be 0\n");
                        return -EINVAL;
                }

                lim->max_secure_erase_sectors = v;

                virtio_cread(vdev, struct virtio_blk_config,
                             max_secure_erase_seg, &v);

                /* max_secure_erase_seg should not be zero, the device should set a
                 * valid number of segments
                 */
                if (!v) {
                        dev_err(&vdev->dev,
                                "virtio_blk: max_secure_erase_seg can't be 0\n");
                        return -EINVAL;
                }

                max_discard_segs = min_not_zero(max_discard_segs, v);
        }

        if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD) ||
            virtio_has_feature(vdev, VIRTIO_BLK_F_SECURE_ERASE)) {
                /* max_discard_seg and discard_granularity will be 0 only
                 * if max_discard_seg and discard_sector_alignment fields in the virtio
                 * config are 0 and VIRTIO_BLK_F_SECURE_ERASE feature is not negotiated.
                 * In this case, we use default values.
                 */
                if (!max_discard_segs)
                        max_discard_segs = sg_elems;

                lim->max_discard_segments =
                        min(max_discard_segs, MAX_DISCARD_SEGMENTS);

                if (discard_granularity)
                        lim->discard_granularity =
                                discard_granularity << SECTOR_SHIFT;
                else
                        lim->discard_granularity = lim->logical_block_size;
        }

        if (virtio_has_feature(vdev, VIRTIO_BLK_F_ZONED)) {
                u8 model;

                virtio_cread(vdev, struct virtio_blk_config, zoned.model, &model);
                switch (model) {
                case VIRTIO_BLK_Z_NONE:
                case VIRTIO_BLK_Z_HA:
                        /* treat host-aware devices as non-zoned */
                        return 0;
                case VIRTIO_BLK_Z_HM:
                        err = virtblk_read_zoned_limits(vblk, lim);
                        if (err)
                                return err;
                        break;
                default:
                        dev_err(&vdev->dev, "unsupported zone model %d\n", model);
                        return -EINVAL;
                }
        }

        return 0;
}

static int virtblk_probe(struct virtio_device *vdev)
{
        struct virtio_blk *vblk;
        struct queue_limits lim = {
                .features               = BLK_FEAT_ROTATIONAL,
                .logical_block_size     = SECTOR_SIZE,
        };
        int err, index;
        unsigned int queue_depth;

        if (!vdev->config->get) {
                dev_err(&vdev->dev, "%s failure: config access disabled\n",
                        __func__);
                return -EINVAL;
        }

        err = ida_alloc_range(&vd_index_ida, 0,
                              minor_to_index(1 << MINORBITS) - 1, GFP_KERNEL);
        if (err < 0)
                goto out;
        index = err;

        vdev->priv = vblk = kmalloc_obj(*vblk);
        if (!vblk) {
                err = -ENOMEM;
                goto out_free_index;
        }

        mutex_init(&vblk->vdev_mutex);

        vblk->vdev = vdev;

        INIT_WORK(&vblk->config_work, virtblk_config_changed_work);

        err = init_vq(vblk);
        if (err)
                goto out_free_vblk;

        /* Default queue sizing is to fill the ring. */
        if (!virtblk_queue_depth) {
                queue_depth = vblk->vqs[0].vq->num_free;
                /* ... but without indirect descs, we use 2 descs per req */
                if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
                        queue_depth /= 2;
        } else {
                queue_depth = virtblk_queue_depth;
        }

        memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
        vblk->tag_set.ops = &virtio_mq_ops;
        vblk->tag_set.queue_depth = queue_depth;
        vblk->tag_set.numa_node = NUMA_NO_NODE;
        vblk->tag_set.cmd_size =
                sizeof(struct virtblk_req) +
                sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT;
        vblk->tag_set.driver_data = vblk;
        vblk->tag_set.nr_hw_queues = vblk->num_vqs;
        vblk->tag_set.nr_maps = 1;
        if (vblk->io_queues[HCTX_TYPE_POLL])
                vblk->tag_set.nr_maps = 3;

        err = blk_mq_alloc_tag_set(&vblk->tag_set);
        if (err)
                goto out_free_vq;

        err = virtblk_read_limits(vblk, &lim);
        if (err)
                goto out_free_tags;

        if (virtblk_get_cache_mode(vdev))
                lim.features |= BLK_FEAT_WRITE_CACHE;

        vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, &lim, vblk);
        if (IS_ERR(vblk->disk)) {
                err = PTR_ERR(vblk->disk);
                goto out_free_tags;
        }

        virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);

        vblk->disk->major = major;
        vblk->disk->first_minor = index_to_minor(index);
        vblk->disk->minors = 1 << PART_BITS;
        vblk->disk->private_data = vblk;
        vblk->disk->fops = &virtblk_fops;
        vblk->index = index;

        /* If disk is read-only in the host, the guest should obey */
        if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
                set_disk_ro(vblk->disk, 1);

        virtblk_update_capacity(vblk, false);
        virtio_device_ready(vdev);

        /*
         * All steps that follow use the VQs therefore they need to be
         * placed after the virtio_device_ready() call above.
         */
        if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
            (lim.features & BLK_FEAT_ZONED)) {
                err = blk_revalidate_disk_zones(vblk->disk);
                if (err)
                        goto out_cleanup_disk;
        }

        err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
        if (err)
                goto out_cleanup_disk;

        return 0;

out_cleanup_disk:
        put_disk(vblk->disk);
out_free_tags:
        blk_mq_free_tag_set(&vblk->tag_set);
out_free_vq:
        vdev->config->del_vqs(vdev);
        kfree(vblk->vqs);
out_free_vblk:
        kfree(vblk);
out_free_index:
        ida_free(&vd_index_ida, index);
out:
        return err;
}

static void virtblk_remove(struct virtio_device *vdev)
{
        struct virtio_blk *vblk = vdev->priv;

        /* Make sure no work handler is accessing the device. */
        flush_work(&vblk->config_work);

        del_gendisk(vblk->disk);
        blk_mq_free_tag_set(&vblk->tag_set);

        mutex_lock(&vblk->vdev_mutex);

        /* Stop all the virtqueues. */
        virtio_reset_device(vdev);

        /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
        vblk->vdev = NULL;

        vdev->config->del_vqs(vdev);
        kfree(vblk->vqs);

        mutex_unlock(&vblk->vdev_mutex);

        put_disk(vblk->disk);
}

static int virtblk_freeze_priv(struct virtio_device *vdev)
{
        struct virtio_blk *vblk = vdev->priv;
        struct request_queue *q = vblk->disk->queue;
        unsigned int memflags;

        /* Ensure no requests in virtqueues before deleting vqs. */
        memflags = blk_mq_freeze_queue(q);
        blk_mq_quiesce_queue_nowait(q);
        blk_mq_unfreeze_queue(q, memflags);

        /* Ensure we don't receive any more interrupts */
        virtio_reset_device(vdev);

        /* Make sure no work handler is accessing the device. */
        flush_work(&vblk->config_work);

        vdev->config->del_vqs(vdev);
        kfree(vblk->vqs);
        /*
         * Set to NULL to prevent freeing vqs again after a failed vqs
         * allocation during resume. Note that kfree() already handles NULL
         * pointers safely.
         */
        vblk->vqs = NULL;

        return 0;
}

static int virtblk_restore_priv(struct virtio_device *vdev)
{
        struct virtio_blk *vblk = vdev->priv;
        int ret;

        ret = init_vq(vdev->priv);
        if (ret)
                return ret;

        virtio_device_ready(vdev);
        blk_mq_unquiesce_queue(vblk->disk->queue);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int virtblk_freeze(struct virtio_device *vdev)
{
        return virtblk_freeze_priv(vdev);
}

static int virtblk_restore(struct virtio_device *vdev)
{
        return virtblk_restore_priv(vdev);
}
#endif

static int virtblk_reset_prepare(struct virtio_device *vdev)
{
        return virtblk_freeze_priv(vdev);
}

static int virtblk_reset_done(struct virtio_device *vdev)
{
        return virtblk_restore_priv(vdev);
}

static const struct virtio_device_id id_table[] = {
        { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
        { 0 },
};

static unsigned int features_legacy[] = {
        VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
        VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
        VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
        VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
        VIRTIO_BLK_F_SECURE_ERASE,
}
;
static unsigned int features[] = {
        VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
        VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
        VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
        VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
        VIRTIO_BLK_F_SECURE_ERASE, VIRTIO_BLK_F_ZONED,
};

static struct virtio_driver virtio_blk = {
        .feature_table                  = features,
        .feature_table_size             = ARRAY_SIZE(features),
        .feature_table_legacy           = features_legacy,
        .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
        .driver.name                    = KBUILD_MODNAME,
        .id_table                       = id_table,
        .probe                          = virtblk_probe,
        .remove                         = virtblk_remove,
        .config_changed                 = virtblk_config_changed,
#ifdef CONFIG_PM_SLEEP
        .freeze                         = virtblk_freeze,
        .restore                        = virtblk_restore,
#endif
        .reset_prepare                  = virtblk_reset_prepare,
        .reset_done                     = virtblk_reset_done,
};

static int __init virtio_blk_init(void)
{
        int error;

        virtblk_wq = alloc_workqueue("virtio-blk", WQ_PERCPU, 0);
        if (!virtblk_wq)
                return -ENOMEM;

        major = register_blkdev(0, "virtblk");
        if (major < 0) {
                error = major;
                goto out_destroy_workqueue;
        }

        error = register_virtio_driver(&virtio_blk);
        if (error)
                goto out_unregister_blkdev;
        return 0;

out_unregister_blkdev:
        unregister_blkdev(major, "virtblk");
out_destroy_workqueue:
        destroy_workqueue(virtblk_wq);
        return error;
}

static void __exit virtio_blk_fini(void)
{
        unregister_virtio_driver(&virtio_blk);
        unregister_blkdev(major, "virtblk");
        destroy_workqueue(virtblk_wq);
}
module_init(virtio_blk_init);
module_exit(virtio_blk_fini);

MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio block driver");
MODULE_LICENSE("GPL");