//#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/virtio.h> #include <linux/virtio_blk.h> #include <linux/scatterlist.h> #include <linux/string_helpers.h> #include <scsi/scsi_cmnd.h> #include <linux/idr.h> #include <linux/blk-mq.h> #include <linux/numa.h> #define PART_BITS 4 static int major; static DEFINE_IDA(vd_index_ida); static struct workqueue_struct *virtblk_wq; struct virtio_blk { struct virtio_device *vdev; struct virtqueue *vq; spinlock_t vq_lock; /* 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; /* Lock for config space updates */ struct mutex config_lock; /* enable config space updates */ bool config_enable; /* What host tells us, plus 2 for header & tailer. */ unsigned int sg_elems; /* Ida index - used to track minor number allocations. */ int index; }; struct virtblk_req { struct request *req; struct virtio_blk_outhdr out_hdr; struct virtio_scsi_inhdr in_hdr; u8 status; struct scatterlist sg[]; }; 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; } } static int __virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr, struct scatterlist *data_sg, bool have_data) { struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6]; unsigned int num_out = 0, num_in = 0; int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT; sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr)); sgs[num_out++] = &hdr; /* * 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. */ if (type == VIRTIO_BLK_T_SCSI_CMD) { sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len); sgs[num_out++] = &cmd; } if (have_data) { if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT) sgs[num_out++] = data_sg; else sgs[num_out + num_in++] = data_sg; } if (type == VIRTIO_BLK_T_SCSI_CMD) { sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE); sgs[num_out + num_in++] = &sense; sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr)); sgs[num_out + num_in++] = &inhdr; } 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); } static inline void virtblk_request_done(struct request *req) { struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); int error = virtblk_result(vbr); if (req->cmd_type == REQ_TYPE_BLOCK_PC) { req->resid_len = vbr->in_hdr.residual; req->sense_len = vbr->in_hdr.sense_len; req->errors = vbr->in_hdr.errors; } else if (req->cmd_type == REQ_TYPE_SPECIAL) { req->errors = (error != 0); } blk_mq_end_io(req, error); } static void virtblk_done(struct virtqueue *vq) { struct virtio_blk *vblk = vq->vdev->priv; bool req_done = false; struct virtblk_req *vbr; unsigned long flags; unsigned int len; spin_lock_irqsave(&vblk->vq_lock, flags); do { virtqueue_disable_cb(vq); while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { blk_mq_complete_request(vbr->req); req_done = true; } if (unlikely(virtqueue_is_broken(vq))) break; } 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->vq_lock, flags); } static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) { struct virtio_blk *vblk = hctx->queue->queuedata; struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); unsigned long flags; unsigned int num; const bool last = (req->cmd_flags & REQ_END) != 0; int err; bool notify = false; BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); vbr->req = req; if (req->cmd_flags & REQ_FLUSH) { vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; vbr->out_hdr.sector = 0; vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); } else { switch (req->cmd_type) { case REQ_TYPE_FS: vbr->out_hdr.type = 0; vbr->out_hdr.sector = blk_rq_pos(vbr->req); vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); break; case REQ_TYPE_BLOCK_PC: vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; vbr->out_hdr.sector = 0; vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); break; case REQ_TYPE_SPECIAL: vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID; vbr->out_hdr.sector = 0; vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); break; default: /* We don't put anything else in the queue. */ BUG(); } } num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg); if (num) { if (rq_data_dir(vbr->req) == WRITE) vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; else vbr->out_hdr.type |= VIRTIO_BLK_T_IN; } spin_lock_irqsave(&vblk->vq_lock, flags); err = __virtblk_add_req(vblk->vq, vbr, vbr->sg, num); if (err) { virtqueue_kick(vblk->vq); blk_mq_stop_hw_queue(hctx); spin_unlock_irqrestore(&vblk->vq_lock, flags); /* 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; } if (last && virtqueue_kick_prepare(vblk->vq)) notify = true; spin_unlock_irqrestore(&vblk->vq_lock, flags); if (notify) virtqueue_notify(vblk->vq); return BLK_MQ_RQ_QUEUE_OK; } /* 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 *req; struct bio *bio; int err; bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL); if (IS_ERR(bio)) return PTR_ERR(bio); req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); if (IS_ERR(req)) { bio_put(bio); return PTR_ERR(req); } req->cmd_type = REQ_TYPE_SPECIAL; err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); blk_put_request(req); return err; } static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long data) { 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)) return -ENOTTY; return scsi_cmd_blk_ioctl(bdev, 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; /* 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(bd->bd_disk) >> 11; } return 0; } static const struct block_device_operations virtblk_fops = { .ioctl = virtblk_ioctl, .owner = THIS_MODULE, .getgeo = virtblk_getgeo, }; 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 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; } DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 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]; char *envp[] = { "RESIZE=1", NULL }; u64 capacity, size; mutex_lock(&vblk->config_lock); if (!vblk->config_enable) goto done; /* Host must always specify the capacity. */ virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity); /* 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; } size = capacity * queue_logical_block_size(q); string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2)); string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10)); 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); revalidate_disk(vblk->disk); kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp); done: mutex_unlock(&vblk->config_lock); } 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 = 0; /* We expect one virtqueue, for output. */ vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests"); if (IS_ERR(vblk->vq)) err = PTR_ERR(vblk->vq); 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 (err) writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE); 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; if (writeback) blk_queue_flush(vblk->disk->queue, REQ_FLUSH); else blk_queue_flush(vblk->disk->queue, 0); 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; virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i); 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); static int virtblk_init_request(void *data, struct request *rq, unsigned int hctx_idx, unsigned int request_idx, unsigned int numa_node) { struct virtio_blk *vblk = data; struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq); sg_init_table(vbr->sg, vblk->sg_elems); return 0; } static struct blk_mq_ops virtio_mq_ops = { .queue_rq = virtio_queue_rq, .map_queue = blk_mq_map_queue, .complete = virtblk_request_done, .init_request = virtblk_init_request, }; static unsigned int virtblk_queue_depth; module_param_named(queue_depth, virtblk_queue_depth, uint, 0444); static int virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk; struct request_queue *q; int err, index; u64 cap; u32 v, blk_size, sg_elems, opt_io_size; u16 min_io_size; u8 physical_block_exp, alignment_offset; err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS), GFP_KERNEL); if (err < 0) goto out; index = 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; /* We need an extra sg elements at head and tail. */ sg_elems += 2; vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); if (!vblk) { err = -ENOMEM; goto out_free_index; } vblk->vdev = vdev; vblk->sg_elems = sg_elems; mutex_init(&vblk->config_lock); INIT_WORK(&vblk->config_work, virtblk_config_changed_work); vblk->config_enable = true; err = init_vq(vblk); if (err) goto out_free_vblk; spin_lock_init(&vblk->vq_lock); /* 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_free_vq; } /* Default queue sizing is to fill the ring. */ if (!virtblk_queue_depth) { virtblk_queue_depth = vblk->vq->num_free; /* ... but without indirect descs, we use 2 descs per req */ if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) virtblk_queue_depth /= 2; } memset(&vblk->tag_set, 0, sizeof(vblk->tag_set)); vblk->tag_set.ops = &virtio_mq_ops; vblk->tag_set.nr_hw_queues = 1; 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 = sizeof(struct virtblk_req) + sizeof(struct scatterlist) * sg_elems; vblk->tag_set.driver_data = vblk; err = blk_mq_alloc_tag_set(&vblk->tag_set); if (err) goto out_put_disk; q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set); if (!q) { err = -ENOMEM; goto out_free_tags; } q->queuedata = vblk; 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->private_data = vblk; vblk->disk->fops = &virtblk_fops; vblk->disk->driverfs_dev = &vdev->dev; vblk->index = index; /* configure queue flush support */ virtblk_update_cache_mode(vdev); /* 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. */ virtio_cread(vdev, struct virtio_blk_config, capacity, &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_segments(q, vblk->sg_elems-2); /* No need to bounce any requests */ blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); /* No real sector limit. */ blk_queue_max_hw_sectors(q, -1U); /* 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) blk_queue_max_segment_size(q, v); else blk_queue_max_segment_size(q, -1U); /* Host can optionally specify the block size of the device */ err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE, struct virtio_blk_config, blk_size, &blk_size); if (!err) blk_queue_logical_block_size(q, blk_size); else blk_size = queue_logical_block_size(q); /* 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) blk_queue_physical_block_size(q, blk_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) blk_queue_alignment_offset(q, blk_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) blk_queue_io_min(q, blk_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) blk_queue_io_opt(q, blk_size * opt_io_size); add_disk(vblk->disk); err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); if (err) goto out_del_disk; 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; return 0; out_del_disk: del_gendisk(vblk->disk); blk_cleanup_queue(vblk->disk->queue); out_free_tags: blk_mq_free_tag_set(&vblk->tag_set); out_put_disk: put_disk(vblk->disk); out_free_vq: vdev->config->del_vqs(vdev); out_free_vblk: kfree(vblk); out_free_index: ida_simple_remove(&vd_index_ida, index); out: return err; } static void virtblk_remove(struct virtio_device *vdev) { struct virtio_blk *vblk = vdev->priv; int index = vblk->index; int refc; /* Prevent config work handler from accessing the device. */ mutex_lock(&vblk->config_lock); vblk->config_enable = false; mutex_unlock(&vblk->config_lock); del_gendisk(vblk->disk); blk_cleanup_queue(vblk->disk->queue); blk_mq_free_tag_set(&vblk->tag_set); /* Stop all the virtqueues. */ vdev->config->reset(vdev); flush_work(&vblk->config_work); refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount); put_disk(vblk->disk); vdev->config->del_vqs(vdev); kfree(vblk); /* Only free device id if we don't have any users */ if (refc == 1) ida_simple_remove(&vd_index_ida, index); } #ifdef CONFIG_PM_SLEEP 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); /* Prevent config work handler from accessing the device. */ mutex_lock(&vblk->config_lock); vblk->config_enable = false; mutex_unlock(&vblk->config_lock); flush_work(&vblk->config_work); blk_mq_stop_hw_queues(vblk->disk->queue); vdev->config->del_vqs(vdev); return 0; } static int virtblk_restore(struct virtio_device *vdev) { struct virtio_blk *vblk = vdev->priv; int ret; vblk->config_enable = true; ret = init_vq(vdev->priv); if (!ret) blk_mq_start_stopped_hw_queues(vblk->disk->queue, true); return ret; } #endif static const struct virtio_device_id id_table[] = { { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, { 0 }, }; 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_SCSI, VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE }; 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 = virtblk_remove, .config_changed = virtblk_config_changed, #ifdef CONFIG_PM_SLEEP .freeze = virtblk_freeze, .restore = virtblk_restore, #endif }; static int __init init(void) { int error; virtblk_wq = alloc_workqueue("virtio-blk", 0, 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 fini(void) { unregister_blkdev(major, "virtblk"); unregister_virtio_driver(&virtio_blk); destroy_workqueue(virtblk_wq); } module_init(init); module_exit(fini); MODULE_DEVICE_TABLE(virtio, id_table); MODULE_DESCRIPTION("Virtio block driver"); MODULE_LICENSE("GPL");