//#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 VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS) static unsigned char virtblk_index = 'a'; 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; /* Scatterlist: can be too big for stack. */ struct scatterlist sg[VIRTIO_MAX_SG]; }; struct virtblk_req { struct list_head list; struct request *req; struct virtio_blk_outhdr out_hdr; struct virtio_blk_inhdr in_hdr; }; static bool 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 uptodate; switch (vbr->in_hdr.status) { case VIRTIO_BLK_S_OK: uptodate = 1; break; case VIRTIO_BLK_S_UNSUPP: uptodate = -ENOTTY; break; default: uptodate = 0; break; } end_dequeued_request(vbr->req, uptodate); 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); return true; } 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 = vbr->req->sector; vbr->out_hdr.ioprio = vbr->req->ioprio; } 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 = vbr->req->ioprio; } 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; /* This init could be done at vblk creation time */ sg_init_table(vblk->sg, VIRTIO_MAX_SG); 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->in_hdr, sizeof(vbr->in_hdr)); 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 > ARRAY_SIZE(vblk->sg)); /* 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 inode *inode, struct file *filp, unsigned cmd, unsigned long data) { return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue, inode->i_bdev->bd_disk, cmd, (void __user *)data); } static struct block_device_operations virtblk_fops = { .ioctl = virtblk_ioctl, .owner = THIS_MODULE, }; static int virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk; int err, major; void *token; unsigned int len; u64 cap; u32 v; vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); if (!vblk) { err = -ENOMEM; goto out; } INIT_LIST_HEAD(&vblk->reqs); spin_lock_init(&vblk->lock); vblk->vdev = vdev; /* We expect one virtqueue, for output. */ vblk->vq = vdev->config->find_vq(vdev, 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; } major = register_blkdev(0, "virtblk"); if (major < 0) { err = major; goto out_mempool; } /* FIXME: How many partitions? How long is a piece of string? */ vblk->disk = alloc_disk(1 << 4); if (!vblk->disk) { err = -ENOMEM; goto out_unregister_blkdev; } vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); if (!vblk->disk->queue) { err = -ENOMEM; goto out_put_disk; } sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++); vblk->disk->major = major; vblk->disk->first_minor = 0; vblk->disk->private_data = vblk; vblk->disk->fops = &virtblk_fops; /* If barriers are supported, tell block layer that queue is ordered */ token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len); if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER)) blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap); if (err) { dev_err(&vdev->dev, "Bad/missing capacity in config\n"); goto out_cleanup_queue; } /* 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); err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v); if (!err) blk_queue_max_segment_size(vblk->disk->queue, v); else if (err != -ENOENT) { dev_err(&vdev->dev, "Bad SIZE_MAX in config\n"); goto out_cleanup_queue; } err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v); if (!err) blk_queue_max_hw_segments(vblk->disk->queue, v); else if (err != -ENOENT) { dev_err(&vdev->dev, "Bad SEG_MAX in config\n"); goto out_cleanup_queue; } add_disk(vblk->disk); return 0; out_cleanup_queue: blk_cleanup_queue(vblk->disk->queue); out_put_disk: put_disk(vblk->disk); out_unregister_blkdev: unregister_blkdev(major, "virtblk"); 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; int major = vblk->disk->major; BUG_ON(!list_empty(&vblk->reqs)); blk_cleanup_queue(vblk->disk->queue); put_disk(vblk->disk); unregister_blkdev(major, "virtblk"); mempool_destroy(vblk->pool); /* There should be nothing in the queue now, so no need to shutdown */ vdev->config->del_vq(vblk->vq); kfree(vblk); } static struct virtio_device_id id_table[] = { { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, { 0 }, }; static struct virtio_driver virtio_blk = { .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) { return register_virtio_driver(&virtio_blk); } static void __exit fini(void) { 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");