virtio_blk.c 23.1 KB
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//#define DEBUG
#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/blkdev.h>
#include <linux/hdreg.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/virtio.h>
#include <linux/virtio_blk.h>
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#include <linux/scatterlist.h>
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#include <linux/string_helpers.h>
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#include <scsi/scsi_cmnd.h>
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#include <linux/idr.h>
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#include <linux/blk-mq.h>
#include <linux/numa.h>
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#define PART_BITS 4
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#define VQ_NAME_LEN 16
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static int major;
static DEFINE_IDA(vd_index_ida);

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

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struct virtio_blk {
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	struct virtio_device *vdev;

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

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

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

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	/* What host tells us, plus 2 for header & tailer. */
	unsigned int sg_elems;

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	/* Ida index - used to track minor number allocations. */
	int index;
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	/* num of vqs */
	int num_vqs;
	struct virtio_blk_vq *vqs;
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};

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struct virtblk_req {
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	struct scsi_request sreq;	/* for SCSI passthrough */
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	struct request *req;
	struct virtio_blk_outhdr out_hdr;
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	struct virtio_scsi_inhdr in_hdr;
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	u8 status;
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	u8 sense[SCSI_SENSE_BUFFERSIZE];
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	struct scatterlist sg[];
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};

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static inline int virtblk_result(struct virtblk_req *vbr)
{
	switch (vbr->status) {
	case VIRTIO_BLK_S_OK:
		return 0;
	case VIRTIO_BLK_S_UNSUPP:
		return -ENOTTY;
	default:
		return -EIO;
	}
}

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static int __virtblk_add_req(struct virtqueue *vq,
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			     struct virtblk_req *vbr,
			     struct scatterlist *data_sg,
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			     bool have_data)
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{
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	struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
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	unsigned int num_out = 0, num_in = 0;
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	__virtio32 type = vbr->out_hdr.type & ~cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT);
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	sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
	sgs[num_out++] = &hdr;

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	/*
	 * If this is a packet command we need a couple of additional headers.
	 * Behind the normal outhdr we put a segment with the scsi command
	 * block, and before the normal inhdr we put the sense data and the
	 * inhdr with additional status information.
	 */
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	if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
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		sg_init_one(&cmd, vbr->sreq.cmd, vbr->sreq.cmd_len);
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		sgs[num_out++] = &cmd;
	}

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

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	if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
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		sg_init_one(&sense, vbr->sense, SCSI_SENSE_BUFFERSIZE);
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		sgs[num_out + num_in++] = &sense;
		sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
		sgs[num_out + num_in++] = &inhdr;
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	}

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

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

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static inline void virtblk_request_done(struct request *req)
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{
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	struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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	struct virtio_blk *vblk = req->q->queuedata;
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	int error = virtblk_result(vbr);

	if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
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		scsi_req(req)->resid_len =
			virtio32_to_cpu(vblk->vdev, vbr->in_hdr.residual);
		vbr->sreq.sense_len =
			virtio32_to_cpu(vblk->vdev, vbr->in_hdr.sense_len);
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		req->errors = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.errors);
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	} else if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
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		req->errors = (error != 0);
	}

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	blk_mq_end_request(req, error);
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}

static void virtblk_done(struct virtqueue *vq)
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{
	struct virtio_blk *vblk = vq->vdev->priv;
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	bool req_done = false;
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	int qid = vq->index;
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	struct virtblk_req *vbr;
	unsigned long flags;
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	unsigned int len;
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	spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
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	do {
		virtqueue_disable_cb(vq);
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		while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
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			blk_mq_complete_request(vbr->req, vbr->req->errors);
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			req_done = true;
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		}
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		if (unlikely(virtqueue_is_broken(vq)))
			break;
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	} while (!virtqueue_enable_cb(vq));
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	/* In case queue is stopped waiting for more buffers. */
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	if (req_done)
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		blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
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	spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
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}

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static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
			   const struct blk_mq_queue_data *bd)
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{
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	struct virtio_blk *vblk = hctx->queue->queuedata;
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	struct request *req = bd->rq;
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	struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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	unsigned long flags;
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	unsigned int num;
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	int qid = hctx->queue_num;
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	int err;
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	bool notify = false;
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	BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
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	vbr->req = req;
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	if (req_op(req) == REQ_OP_FLUSH) {
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		vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_FLUSH);
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		vbr->out_hdr.sector = 0;
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		vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
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	} else {
		switch (req->cmd_type) {
		case REQ_TYPE_FS:
			vbr->out_hdr.type = 0;
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			vbr->out_hdr.sector = cpu_to_virtio64(vblk->vdev, blk_rq_pos(vbr->req));
			vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
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			break;
		case REQ_TYPE_BLOCK_PC:
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			vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_SCSI_CMD);
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			vbr->out_hdr.sector = 0;
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			vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
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			break;
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		case REQ_TYPE_DRV_PRIV:
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			vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_GET_ID);
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			vbr->out_hdr.sector = 0;
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			vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
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			break;
		default:
			/* We don't put anything else in the queue. */
			BUG();
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		}
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	}

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	blk_mq_start_request(req);

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	num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
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	if (num) {
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		if (rq_data_dir(vbr->req) == WRITE)
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			vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_OUT);
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		else
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			vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_IN);
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	}

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	spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
	err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
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	if (err) {
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		virtqueue_kick(vblk->vqs[qid].vq);
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		blk_mq_stop_hw_queue(hctx);
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		spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
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		/* Out of mem doesn't actually happen, since we fall back
		 * to direct descriptors */
		if (err == -ENOMEM || err == -ENOSPC)
			return BLK_MQ_RQ_QUEUE_BUSY;
		return BLK_MQ_RQ_QUEUE_ERROR;
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	}

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

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/* 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;
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	struct request_queue *q = vblk->disk->queue;
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	struct request *req;
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	int err;
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	req = blk_get_request(q, READ, GFP_KERNEL);
	if (IS_ERR(req))
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		return PTR_ERR(req);
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	req->cmd_type = REQ_TYPE_DRV_PRIV;
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	err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
	if (err)
		goto out;

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	err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
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out:
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	blk_put_request(req);
	return err;
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}

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static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
			     unsigned int cmd, unsigned long data)
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{
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	struct gendisk *disk = bdev->bd_disk;
	struct virtio_blk *vblk = disk->private_data;

	/*
	 * Only allow the generic SCSI ioctls if the host can support it.
	 */
	if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
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		return -ENOTTY;
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	return scsi_cmd_blk_ioctl(bdev, mode, cmd,
				  (void __user *)data);
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}

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

	/* see if the host passed in geometry config */
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	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);
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	} else {
		/* some standard values, similar to sd */
		geo->heads = 1 << 6;
		geo->sectors = 1 << 5;
		geo->cylinders = get_capacity(bd->bd_disk) >> 11;
	}
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	return 0;
}

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static const struct block_device_operations virtblk_fops = {
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	.ioctl  = virtblk_ioctl,
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	.owner  = THIS_MODULE,
	.getgeo = virtblk_getgeo,
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};

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

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

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static ssize_t virtblk_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;
}
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static DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
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static void virtblk_config_changed_work(struct work_struct *work)
{
	struct virtio_blk *vblk =
		container_of(work, struct virtio_blk, config_work);
	struct virtio_device *vdev = vblk->vdev;
	struct request_queue *q = vblk->disk->queue;
	char cap_str_2[10], cap_str_10[10];
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	char *envp[] = { "RESIZE=1", NULL };
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	u64 capacity;
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	/* Host must always specify the capacity. */
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	virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
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	/* If capacity is too big, truncate with warning. */
	if ((sector_t)capacity != capacity) {
		dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
			 (unsigned long long)capacity);
		capacity = (sector_t)-1;
	}

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	string_get_size(capacity, queue_logical_block_size(q),
			STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
	string_get_size(capacity, queue_logical_block_size(q),
			STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
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	dev_notice(&vdev->dev,
		  "new size: %llu %d-byte logical blocks (%s/%s)\n",
		  (unsigned long long)capacity,
		  queue_logical_block_size(q),
		  cap_str_10, cap_str_2);

	set_capacity(vblk->disk, capacity);
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	revalidate_disk(vblk->disk);
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	kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
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}

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

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

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static int init_vq(struct virtio_blk *vblk)
{
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	int err;
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	int i;
	vq_callback_t **callbacks;
	const char **names;
	struct virtqueue **vqs;
	unsigned short num_vqs;
	struct virtio_device *vdev = vblk->vdev;

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

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	vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
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	if (!vblk->vqs)
		return -ENOMEM;
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	names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
	callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
	vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
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	if (!names || !callbacks || !vqs) {
		err = -ENOMEM;
		goto out;
	}
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	for (i = 0; i < num_vqs; i++) {
		callbacks[i] = virtblk_done;
		snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
		names[i] = vblk->vqs[i].name;
	}

	/* Discover virtqueues and write information to configuration.  */
	err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
	if (err)
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		goto out;
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	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;

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out:
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	kfree(vqs);
	kfree(callbacks);
	kfree(names);
	if (err)
		kfree(vblk->vqs);
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	return err;
}

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/*
 * 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;
}

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

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	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
				   struct virtio_blk_config, wce,
				   &writeback);
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	/*
	 * If WCE is not configurable and flush is not available,
	 * assume no writeback cache is in use.
	 */
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	if (err)
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		writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
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	return writeback;
}

static void virtblk_update_cache_mode(struct virtio_device *vdev)
{
	u8 writeback = virtblk_get_cache_mode(vdev);
	struct virtio_blk *vblk = vdev->priv;

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	blk_queue_write_cache(vblk->disk->queue, writeback, false);
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	revalidate_disk(vblk->disk);
}

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

static ssize_t
virtblk_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;
	int i;

	BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
	for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
		if (sysfs_streq(buf, virtblk_cache_types[i]))
			break;

	if (i < 0)
		return -EINVAL;

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	virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
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	virtblk_update_cache_mode(vdev);
	return count;
}

static ssize_t
virtblk_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 snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
}

static const struct device_attribute dev_attr_cache_type_ro =
	__ATTR(cache_type, S_IRUGO,
	       virtblk_cache_type_show, NULL);
static const struct device_attribute dev_attr_cache_type_rw =
	__ATTR(cache_type, S_IRUGO|S_IWUSR,
	       virtblk_cache_type_show, virtblk_cache_type_store);

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static int virtblk_init_request(void *data, struct request *rq,
		unsigned int hctx_idx, unsigned int request_idx,
		unsigned int numa_node)
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{
	struct virtio_blk *vblk = data;
	struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);

543
	vbr->sreq.sense = vbr->sense;
544 545 546 547
	sg_init_table(vbr->sg, vblk->sg_elems);
	return 0;
}

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static struct blk_mq_ops virtio_mq_ops = {
	.queue_rq	= virtio_queue_rq,
550
	.complete	= virtblk_request_done,
551
	.init_request	= virtblk_init_request,
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};

554 555
static unsigned int virtblk_queue_depth;
module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
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557
static int virtblk_probe(struct virtio_device *vdev)
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{
	struct virtio_blk *vblk;
560
	struct request_queue *q;
561
	int err, index;
562

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	u64 cap;
564 565 566
	u32 v, blk_size, sg_elems, opt_io_size;
	u16 min_io_size;
	u8 physical_block_exp, alignment_offset;
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568 569 570 571 572 573
	if (!vdev->config->get) {
		dev_err(&vdev->dev, "%s failure: config access disabled\n",
			__func__);
		return -EINVAL;
	}

574 575 576 577 578
	err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
			     GFP_KERNEL);
	if (err < 0)
		goto out;
	index = err;
579

580
	/* We need to know how many segments before we allocate. */
581 582 583
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
				   struct virtio_blk_config, seg_max,
				   &sg_elems);
584 585 586

	/* We need at least one SG element, whatever they say. */
	if (err || !sg_elems)
587 588 589 590
		sg_elems = 1;

	/* We need an extra sg elements at head and tail. */
	sg_elems += 2;
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	vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
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	if (!vblk) {
		err = -ENOMEM;
594
		goto out_free_index;
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	}

	vblk->vdev = vdev;
598
	vblk->sg_elems = sg_elems;
599

600
	INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
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602 603
	err = init_vq(vblk);
	if (err)
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		goto out_free_vblk;

	/* FIXME: How many partitions?  How long is a piece of string? */
607
	vblk->disk = alloc_disk(1 << PART_BITS);
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	if (!vblk->disk) {
		err = -ENOMEM;
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		goto out_free_vq;
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	}

613
	/* Default queue sizing is to fill the ring. */
614
	if (!virtblk_queue_depth) {
615
		virtblk_queue_depth = vblk->vqs[0].vq->num_free;
616 617
		/* ... but without indirect descs, we use 2 descs per req */
		if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
618
			virtblk_queue_depth /= 2;
619
	}
620 621 622 623 624 625 626

	memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
	vblk->tag_set.ops = &virtio_mq_ops;
	vblk->tag_set.queue_depth = virtblk_queue_depth;
	vblk->tag_set.numa_node = NUMA_NO_NODE;
	vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
	vblk->tag_set.cmd_size =
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		sizeof(struct virtblk_req) +
		sizeof(struct scatterlist) * sg_elems;
629
	vblk->tag_set.driver_data = vblk;
630
	vblk->tag_set.nr_hw_queues = vblk->num_vqs;
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632 633 634 635
	err = blk_mq_alloc_tag_set(&vblk->tag_set);
	if (err)
		goto out_put_disk;

636
	q = blk_mq_init_queue(&vblk->tag_set);
637
	if (IS_ERR(q)) {
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		err = -ENOMEM;
639
		goto out_free_tags;
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	}
641
	vblk->disk->queue = q;
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643
	q->queuedata = vblk;
644

645
	virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
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	vblk->disk->major = major;
648
	vblk->disk->first_minor = index_to_minor(index);
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	vblk->disk->private_data = vblk;
	vblk->disk->fops = &virtblk_fops;
651
	vblk->disk->flags |= GENHD_FL_EXT_DEVT;
652
	vblk->index = index;
653

654
	/* configure queue flush support */
655
	virtblk_update_cache_mode(vdev);
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	/* 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);

661
	/* Host must always specify the capacity. */
662
	virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
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	/* If capacity is too big, truncate with warning. */
	if ((sector_t)cap != cap) {
		dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
			 (unsigned long long)cap);
		cap = (sector_t)-1;
	}
	set_capacity(vblk->disk, cap);

672
	/* We can handle whatever the host told us to handle. */
673
	blk_queue_max_segments(q, vblk->sg_elems-2);
674

675
	/* No need to bounce any requests */
676
	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
677

678
	/* No real sector limit. */
679
	blk_queue_max_hw_sectors(q, -1U);
680

681 682
	/* Host can optionally specify maximum segment size and number of
	 * segments. */
683 684
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
				   struct virtio_blk_config, size_max, &v);
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	if (!err)
686
		blk_queue_max_segment_size(q, v);
687
	else
688
		blk_queue_max_segment_size(q, -1U);
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690
	/* Host can optionally specify the block size of the device */
691 692 693
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
				   struct virtio_blk_config, blk_size,
				   &blk_size);
694
	if (!err)
695 696 697 698 699
		blk_queue_logical_block_size(q, blk_size);
	else
		blk_size = queue_logical_block_size(q);

	/* Use topology information if available */
700 701 702
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
				   struct virtio_blk_config, physical_block_exp,
				   &physical_block_exp);
703 704 705 706
	if (!err && physical_block_exp)
		blk_queue_physical_block_size(q,
				blk_size * (1 << physical_block_exp));

707 708 709
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
				   struct virtio_blk_config, alignment_offset,
				   &alignment_offset);
710 711 712
	if (!err && alignment_offset)
		blk_queue_alignment_offset(q, blk_size * alignment_offset);

713 714 715
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
				   struct virtio_blk_config, min_io_size,
				   &min_io_size);
716 717 718
	if (!err && min_io_size)
		blk_queue_io_min(q, blk_size * min_io_size);

719 720 721
	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
				   struct virtio_blk_config, opt_io_size,
				   &opt_io_size);
722 723 724
	if (!err && opt_io_size)
		blk_queue_io_opt(q, blk_size * opt_io_size);

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	virtio_device_ready(vdev);

727
	device_add_disk(&vdev->dev, vblk->disk);
728 729 730 731
	err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
	if (err)
		goto out_del_disk;

732 733 734 735 736 737 738 739
	if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
		err = device_create_file(disk_to_dev(vblk->disk),
					 &dev_attr_cache_type_rw);
	else
		err = device_create_file(disk_to_dev(vblk->disk),
					 &dev_attr_cache_type_ro);
	if (err)
		goto out_del_disk;
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	return 0;

742 743 744
out_del_disk:
	del_gendisk(vblk->disk);
	blk_cleanup_queue(vblk->disk->queue);
745 746
out_free_tags:
	blk_mq_free_tag_set(&vblk->tag_set);
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out_put_disk:
	put_disk(vblk->disk);
out_free_vq:
750
	vdev->config->del_vqs(vdev);
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out_free_vblk:
	kfree(vblk);
753 754
out_free_index:
	ida_simple_remove(&vd_index_ida, index);
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out:
	return err;
}

759
static void virtblk_remove(struct virtio_device *vdev)
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{
	struct virtio_blk *vblk = vdev->priv;
762
	int index = vblk->index;
763
	int refc;
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765 766
	/* Make sure no work handler is accessing the device. */
	flush_work(&vblk->config_work);
767

768
	del_gendisk(vblk->disk);
769
	blk_cleanup_queue(vblk->disk->queue);
770

771 772
	blk_mq_free_tag_set(&vblk->tag_set);

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	/* Stop all the virtqueues. */
	vdev->config->reset(vdev);

776
	refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
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	put_disk(vblk->disk);
778
	vdev->config->del_vqs(vdev);
779
	kfree(vblk->vqs);
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	kfree(vblk);
781 782 783 784

	/* Only free device id if we don't have any users */
	if (refc == 1)
		ida_simple_remove(&vd_index_ida, index);
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}

787
#ifdef CONFIG_PM_SLEEP
788 789 790 791 792 793 794
static int virtblk_freeze(struct virtio_device *vdev)
{
	struct virtio_blk *vblk = vdev->priv;

	/* Ensure we don't receive any more interrupts */
	vdev->config->reset(vdev);

795
	/* Make sure no work handler is accessing the device. */
796 797
	flush_work(&vblk->config_work);

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	blk_mq_stop_hw_queues(vblk->disk->queue);
799 800 801 802 803 804 805 806 807 808 809

	vdev->config->del_vqs(vdev);
	return 0;
}

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

	ret = init_vq(vdev->priv);
810 811 812 813
	if (ret)
		return ret;

	virtio_device_ready(vdev);
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815 816
	blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
	return 0;
817 818 819
}
#endif

820
static const struct virtio_device_id id_table[] = {
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	{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
	{ 0 },
};

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static unsigned int features_legacy[] = {
826 827
	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_SCSI,
828
	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
829
	VIRTIO_BLK_F_MQ,
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}
;
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,
835
	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
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	VIRTIO_BLK_F_MQ,
837 838
};

839
static struct virtio_driver virtio_blk = {
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840 841 842 843 844 845 846 847 848 849
	.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,
	.driver.owner			= THIS_MODULE,
	.id_table			= id_table,
	.probe				= virtblk_probe,
	.remove				= virtblk_remove,
	.config_changed			= virtblk_config_changed,
850
#ifdef CONFIG_PM_SLEEP
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	.freeze				= virtblk_freeze,
	.restore			= virtblk_restore,
853
#endif
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};

static int __init init(void)
{
858 859 860 861 862 863
	int error;

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

864
	major = register_blkdev(0, "virtblk");
865 866 867 868 869 870 871 872 873 874 875 876 877 878 879
	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;
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}

static void __exit fini(void)
{
	unregister_virtio_driver(&virtio_blk);
885
	unregister_blkdev(major, "virtblk");
886
	destroy_workqueue(virtblk_wq);
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}
module_init(init);
module_exit(fini);

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