| //#define DEBUG |
| #include <linux/spinlock.h> |
| #include <linux/blkdev.h> |
| #include <linux/hdreg.h> |
| #include <linux/virtio.h> |
| #include <linux/virtio_blk.h> |
| #include <linux/scatterlist.h> |
| |
| #define PART_BITS 4 |
| |
| static int major, index; |
| |
| struct virtio_blk |
| { |
| spinlock_t lock; |
| |
| struct virtio_device *vdev; |
| struct virtqueue *vq; |
| |
| /* The disk structure for the kernel. */ |
| struct gendisk *disk; |
| |
| /* Request tracking. */ |
| struct list_head reqs; |
| |
| mempool_t *pool; |
| |
| /* What host tells us, plus 2 for header & tailer. */ |
| unsigned int sg_elems; |
| |
| /* Scatterlist: can be too big for stack. */ |
| struct scatterlist sg[/*sg_elems*/]; |
| }; |
| |
| struct virtblk_req |
| { |
| struct list_head list; |
| struct request *req; |
| struct virtio_blk_outhdr out_hdr; |
| u8 status; |
| }; |
| |
| static void blk_done(struct virtqueue *vq) |
| { |
| struct virtio_blk *vblk = vq->vdev->priv; |
| struct virtblk_req *vbr; |
| unsigned int len; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&vblk->lock, flags); |
| while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { |
| int error; |
| switch (vbr->status) { |
| case VIRTIO_BLK_S_OK: |
| error = 0; |
| break; |
| case VIRTIO_BLK_S_UNSUPP: |
| error = -ENOTTY; |
| break; |
| default: |
| error = -EIO; |
| break; |
| } |
| |
| __blk_end_request_all(vbr->req, error); |
| list_del(&vbr->list); |
| mempool_free(vbr, vblk->pool); |
| } |
| /* In case queue is stopped waiting for more buffers. */ |
| blk_start_queue(vblk->disk->queue); |
| spin_unlock_irqrestore(&vblk->lock, flags); |
| } |
| |
| static bool do_req(struct request_queue *q, struct virtio_blk *vblk, |
| struct request *req) |
| { |
| unsigned long num, out, in; |
| struct virtblk_req *vbr; |
| |
| vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); |
| if (!vbr) |
| /* When another request finishes we'll try again. */ |
| return false; |
| |
| vbr->req = req; |
| if (blk_fs_request(vbr->req)) { |
| vbr->out_hdr.type = 0; |
| vbr->out_hdr.sector = blk_rq_pos(vbr->req); |
| vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); |
| } else if (blk_pc_request(vbr->req)) { |
| vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; |
| vbr->out_hdr.sector = 0; |
| vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); |
| } else { |
| /* We don't put anything else in the queue. */ |
| BUG(); |
| } |
| |
| if (blk_barrier_rq(vbr->req)) |
| vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; |
| |
| sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); |
| num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); |
| sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status)); |
| |
| if (rq_data_dir(vbr->req) == WRITE) { |
| vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; |
| out = 1 + num; |
| in = 1; |
| } else { |
| vbr->out_hdr.type |= VIRTIO_BLK_T_IN; |
| out = 1; |
| in = 1 + num; |
| } |
| |
| if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { |
| mempool_free(vbr, vblk->pool); |
| return false; |
| } |
| |
| list_add_tail(&vbr->list, &vblk->reqs); |
| return true; |
| } |
| |
| static void do_virtblk_request(struct request_queue *q) |
| { |
| struct virtio_blk *vblk = NULL; |
| struct request *req; |
| unsigned int issued = 0; |
| |
| while ((req = elv_next_request(q)) != NULL) { |
| vblk = req->rq_disk->private_data; |
| BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); |
| |
| /* If this request fails, stop queue and wait for something to |
| finish to restart it. */ |
| if (!do_req(q, vblk, req)) { |
| blk_stop_queue(q); |
| break; |
| } |
| blkdev_dequeue_request(req); |
| issued++; |
| } |
| |
| if (issued) |
| vblk->vq->vq_ops->kick(vblk->vq); |
| } |
| |
| static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, |
| unsigned cmd, unsigned long data) |
| { |
| return scsi_cmd_ioctl(bdev->bd_disk->queue, |
| bdev->bd_disk, mode, cmd, |
| (void __user *)data); |
| } |
| |
| /* We provide getgeo only to please some old bootloader/partitioning tools */ |
| static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) |
| { |
| struct virtio_blk *vblk = bd->bd_disk->private_data; |
| struct virtio_blk_geometry vgeo; |
| int err; |
| |
| /* see if the host passed in geometry config */ |
| err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, |
| offsetof(struct virtio_blk_config, geometry), |
| &vgeo); |
| |
| if (!err) { |
| geo->heads = vgeo.heads; |
| geo->sectors = vgeo.sectors; |
| geo->cylinders = vgeo.cylinders; |
| } else { |
| /* some standard values, similar to sd */ |
| geo->heads = 1 << 6; |
| geo->sectors = 1 << 5; |
| geo->cylinders = get_capacity(bd->bd_disk) >> 11; |
| } |
| return 0; |
| } |
| |
| static struct block_device_operations virtblk_fops = { |
| .locked_ioctl = virtblk_ioctl, |
| .owner = THIS_MODULE, |
| .getgeo = virtblk_getgeo, |
| }; |
| |
| static int index_to_minor(int index) |
| { |
| return index << PART_BITS; |
| } |
| |
| static int virtblk_probe(struct virtio_device *vdev) |
| { |
| struct virtio_blk *vblk; |
| int err; |
| u64 cap; |
| u32 v; |
| u32 blk_size, sg_elems; |
| |
| if (index_to_minor(index) >= 1 << MINORBITS) |
| return -ENOSPC; |
| |
| /* We need to know how many segments before we allocate. */ |
| err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, |
| offsetof(struct virtio_blk_config, seg_max), |
| &sg_elems); |
| if (err) |
| sg_elems = 1; |
| |
| /* We need an extra sg elements at head and tail. */ |
| sg_elems += 2; |
| vdev->priv = vblk = kmalloc(sizeof(*vblk) + |
| sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); |
| if (!vblk) { |
| err = -ENOMEM; |
| goto out; |
| } |
| |
| INIT_LIST_HEAD(&vblk->reqs); |
| spin_lock_init(&vblk->lock); |
| vblk->vdev = vdev; |
| vblk->sg_elems = sg_elems; |
| sg_init_table(vblk->sg, vblk->sg_elems); |
| |
| /* We expect one virtqueue, for output. */ |
| vblk->vq = vdev->config->find_vq(vdev, 0, blk_done); |
| if (IS_ERR(vblk->vq)) { |
| err = PTR_ERR(vblk->vq); |
| goto out_free_vblk; |
| } |
| |
| vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); |
| if (!vblk->pool) { |
| err = -ENOMEM; |
| goto out_free_vq; |
| } |
| |
| /* FIXME: How many partitions? How long is a piece of string? */ |
| vblk->disk = alloc_disk(1 << PART_BITS); |
| if (!vblk->disk) { |
| err = -ENOMEM; |
| goto out_mempool; |
| } |
| |
| vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); |
| if (!vblk->disk->queue) { |
| err = -ENOMEM; |
| goto out_put_disk; |
| } |
| |
| queue_flag_set_unlocked(QUEUE_FLAG_VIRT, vblk->disk->queue); |
| |
| if (index < 26) { |
| sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); |
| } else if (index < (26 + 1) * 26) { |
| sprintf(vblk->disk->disk_name, "vd%c%c", |
| 'a' + index / 26 - 1, 'a' + index % 26); |
| } else { |
| const unsigned int m1 = (index / 26 - 1) / 26 - 1; |
| const unsigned int m2 = (index / 26 - 1) % 26; |
| const unsigned int m3 = index % 26; |
| sprintf(vblk->disk->disk_name, "vd%c%c%c", |
| 'a' + m1, 'a' + m2, 'a' + m3); |
| } |
| |
| vblk->disk->major = major; |
| vblk->disk->first_minor = index_to_minor(index); |
| vblk->disk->private_data = vblk; |
| vblk->disk->fops = &virtblk_fops; |
| vblk->disk->driverfs_dev = &vdev->dev; |
| index++; |
| |
| /* If barriers are supported, tell block layer that queue is ordered */ |
| if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) |
| blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); |
| |
| /* 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); |
| |
| /* Host must always specify the capacity. */ |
| vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), |
| &cap, sizeof(cap)); |
| |
| /* 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); |
| |
| /* We can handle whatever the host told us to handle. */ |
| blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); |
| blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); |
| |
| /* No real sector limit. */ |
| blk_queue_max_sectors(vblk->disk->queue, -1U); |
| |
| /* Host can optionally specify maximum segment size and number of |
| * segments. */ |
| err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, |
| offsetof(struct virtio_blk_config, size_max), |
| &v); |
| if (!err) |
| blk_queue_max_segment_size(vblk->disk->queue, v); |
| else |
| blk_queue_max_segment_size(vblk->disk->queue, -1U); |
| |
| /* Host can optionally specify the block size of the device */ |
| err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, |
| offsetof(struct virtio_blk_config, blk_size), |
| &blk_size); |
| if (!err) |
| blk_queue_hardsect_size(vblk->disk->queue, blk_size); |
| |
| add_disk(vblk->disk); |
| return 0; |
| |
| out_put_disk: |
| put_disk(vblk->disk); |
| out_mempool: |
| mempool_destroy(vblk->pool); |
| out_free_vq: |
| vdev->config->del_vq(vblk->vq); |
| out_free_vblk: |
| kfree(vblk); |
| out: |
| return err; |
| } |
| |
| static void virtblk_remove(struct virtio_device *vdev) |
| { |
| struct virtio_blk *vblk = vdev->priv; |
| |
| /* Nothing should be pending. */ |
| BUG_ON(!list_empty(&vblk->reqs)); |
| |
| /* Stop all the virtqueues. */ |
| vdev->config->reset(vdev); |
| |
| del_gendisk(vblk->disk); |
| blk_cleanup_queue(vblk->disk->queue); |
| put_disk(vblk->disk); |
| mempool_destroy(vblk->pool); |
| vdev->config->del_vq(vblk->vq); |
| kfree(vblk); |
| } |
| |
| static struct virtio_device_id id_table[] = { |
| { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, |
| { 0 }, |
| }; |
| |
| static unsigned int features[] = { |
| VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, |
| VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, |
| }; |
| |
| static struct virtio_driver virtio_blk = { |
| .feature_table = features, |
| .feature_table_size = ARRAY_SIZE(features), |
| .driver.name = KBUILD_MODNAME, |
| .driver.owner = THIS_MODULE, |
| .id_table = id_table, |
| .probe = virtblk_probe, |
| .remove = __devexit_p(virtblk_remove), |
| }; |
| |
| static int __init init(void) |
| { |
| major = register_blkdev(0, "virtblk"); |
| if (major < 0) |
| return major; |
| return register_virtio_driver(&virtio_blk); |
| } |
| |
| static void __exit fini(void) |
| { |
| unregister_blkdev(major, "virtblk"); |
| unregister_virtio_driver(&virtio_blk); |
| } |
| module_init(init); |
| module_exit(fini); |
| |
| MODULE_DEVICE_TABLE(virtio, id_table); |
| MODULE_DESCRIPTION("Virtio block driver"); |
| MODULE_LICENSE("GPL"); |