309 lines
7.1 KiB
C
309 lines
7.1 KiB
C
![]() |
//#define DEBUG
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#include <linux/spinlock.h>
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#include <linux/blkdev.h>
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#include <linux/hdreg.h>
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#include <linux/virtio.h>
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#include <linux/virtio_blk.h>
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#include <linux/virtio_blk.h>
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static unsigned char virtblk_index = 'a';
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struct virtio_blk
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{
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spinlock_t lock;
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struct virtio_device *vdev;
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struct virtqueue *vq;
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/* The disk structure for the kernel. */
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struct gendisk *disk;
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/* Request tracking. */
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struct list_head reqs;
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mempool_t *pool;
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/* Scatterlist: can be too big for stack. */
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struct scatterlist sg[3+MAX_PHYS_SEGMENTS];
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};
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struct virtblk_req
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{
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struct list_head list;
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struct request *req;
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struct virtio_blk_outhdr out_hdr;
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struct virtio_blk_inhdr in_hdr;
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};
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static bool blk_done(struct virtqueue *vq)
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{
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struct virtio_blk *vblk = vq->vdev->priv;
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struct virtblk_req *vbr;
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unsigned int len;
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unsigned long flags;
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spin_lock_irqsave(&vblk->lock, flags);
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while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
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int uptodate;
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switch (vbr->in_hdr.status) {
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case VIRTIO_BLK_S_OK:
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uptodate = 1;
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break;
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case VIRTIO_BLK_S_UNSUPP:
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uptodate = -ENOTTY;
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break;
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default:
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uptodate = 0;
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break;
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}
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end_dequeued_request(vbr->req, uptodate);
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list_del(&vbr->list);
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mempool_free(vbr, vblk->pool);
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}
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/* In case queue is stopped waiting for more buffers. */
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blk_start_queue(vblk->disk->queue);
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spin_unlock_irqrestore(&vblk->lock, flags);
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return true;
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}
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static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
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struct request *req)
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{
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unsigned long num, out, in;
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struct virtblk_req *vbr;
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vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
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if (!vbr)
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/* When another request finishes we'll try again. */
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return false;
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vbr->req = req;
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if (blk_fs_request(vbr->req)) {
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vbr->out_hdr.type = 0;
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vbr->out_hdr.sector = vbr->req->sector;
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vbr->out_hdr.ioprio = vbr->req->ioprio;
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} else if (blk_pc_request(vbr->req)) {
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vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
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vbr->out_hdr.sector = 0;
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vbr->out_hdr.ioprio = vbr->req->ioprio;
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} else {
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/* We don't put anything else in the queue. */
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BUG();
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}
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if (blk_barrier_rq(vbr->req))
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vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
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/* We have to zero this, otherwise blk_rq_map_sg gets upset. */
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memset(vblk->sg, 0, sizeof(vblk->sg));
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sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
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num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
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sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
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if (rq_data_dir(vbr->req) == WRITE) {
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vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
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out = 1 + num;
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in = 1;
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} else {
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vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
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out = 1;
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in = 1 + num;
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}
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if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
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mempool_free(vbr, vblk->pool);
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return false;
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}
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list_add_tail(&vbr->list, &vblk->reqs);
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return true;
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}
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static void do_virtblk_request(struct request_queue *q)
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{
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struct virtio_blk *vblk = NULL;
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struct request *req;
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unsigned int issued = 0;
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while ((req = elv_next_request(q)) != NULL) {
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vblk = req->rq_disk->private_data;
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BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
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/* If this request fails, stop queue and wait for something to
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finish to restart it. */
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if (!do_req(q, vblk, req)) {
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blk_stop_queue(q);
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break;
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}
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blkdev_dequeue_request(req);
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issued++;
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}
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if (issued)
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vblk->vq->vq_ops->kick(vblk->vq);
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}
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static int virtblk_ioctl(struct inode *inode, struct file *filp,
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unsigned cmd, unsigned long data)
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{
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return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
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inode->i_bdev->bd_disk, cmd,
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(void __user *)data);
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}
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static struct block_device_operations virtblk_fops = {
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.ioctl = virtblk_ioctl,
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.owner = THIS_MODULE,
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};
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static int virtblk_probe(struct virtio_device *vdev)
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{
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struct virtio_blk *vblk;
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int err, major;
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void *token;
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unsigned int len;
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u64 cap;
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u32 v;
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vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
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if (!vblk) {
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err = -ENOMEM;
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goto out;
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}
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INIT_LIST_HEAD(&vblk->reqs);
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spin_lock_init(&vblk->lock);
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vblk->vdev = vdev;
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/* We expect one virtqueue, for output. */
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vblk->vq = vdev->config->find_vq(vdev, blk_done);
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if (IS_ERR(vblk->vq)) {
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err = PTR_ERR(vblk->vq);
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goto out_free_vblk;
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}
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vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
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if (!vblk->pool) {
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err = -ENOMEM;
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goto out_free_vq;
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}
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major = register_blkdev(0, "virtblk");
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if (major < 0) {
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err = major;
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goto out_mempool;
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}
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/* FIXME: How many partitions? How long is a piece of string? */
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vblk->disk = alloc_disk(1 << 4);
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if (!vblk->disk) {
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err = -ENOMEM;
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goto out_unregister_blkdev;
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}
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vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
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if (!vblk->disk->queue) {
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err = -ENOMEM;
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goto out_put_disk;
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}
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sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
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vblk->disk->major = major;
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vblk->disk->first_minor = 0;
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vblk->disk->private_data = vblk;
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vblk->disk->fops = &virtblk_fops;
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/* If barriers are supported, tell block layer that queue is ordered */
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token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len);
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if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))
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blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
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err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap);
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if (err) {
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dev_err(&vdev->dev, "Bad/missing capacity in config\n");
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goto out_put_disk;
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}
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/* If capacity is too big, truncate with warning. */
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if ((sector_t)cap != cap) {
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dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
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(unsigned long long)cap);
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cap = (sector_t)-1;
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}
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set_capacity(vblk->disk, cap);
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err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v);
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if (!err)
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blk_queue_max_segment_size(vblk->disk->queue, v);
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else if (err != -ENOENT) {
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dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");
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goto out_put_disk;
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}
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err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v);
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if (!err)
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blk_queue_max_hw_segments(vblk->disk->queue, v);
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else if (err != -ENOENT) {
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dev_err(&vdev->dev, "Bad SEG_MAX in config\n");
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goto out_put_disk;
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}
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add_disk(vblk->disk);
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return 0;
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out_put_disk:
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put_disk(vblk->disk);
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out_unregister_blkdev:
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unregister_blkdev(major, "virtblk");
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out_mempool:
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mempool_destroy(vblk->pool);
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out_free_vq:
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vdev->config->del_vq(vblk->vq);
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out_free_vblk:
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kfree(vblk);
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out:
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return err;
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}
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static void virtblk_remove(struct virtio_device *vdev)
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{
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struct virtio_blk *vblk = vdev->priv;
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int major = vblk->disk->major;
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BUG_ON(!list_empty(&vblk->reqs));
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blk_cleanup_queue(vblk->disk->queue);
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put_disk(vblk->disk);
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unregister_blkdev(major, "virtblk");
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mempool_destroy(vblk->pool);
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kfree(vblk);
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}
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
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{ 0 },
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};
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static struct virtio_driver virtio_blk = {
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.driver.name = KBUILD_MODNAME,
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.driver.owner = THIS_MODULE,
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.id_table = id_table,
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.probe = virtblk_probe,
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.remove = __devexit_p(virtblk_remove),
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};
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static int __init init(void)
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{
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return register_virtio_driver(&virtio_blk);
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}
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static void __exit fini(void)
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{
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unregister_virtio_driver(&virtio_blk);
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}
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module_init(init);
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module_exit(fini);
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MODULE_DEVICE_TABLE(virtio, id_table);
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MODULE_DESCRIPTION("Virtio block driver");
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MODULE_LICENSE("GPL");
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