//#define DEBUG #include #include #include #include #include #include #include #include #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; struct virtio_scsi_inhdr in_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 = virtqueue_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; } switch (vbr->req->cmd_type) { case REQ_TYPE_BLOCK_PC: vbr->req->resid_len = vbr->in_hdr.residual; vbr->req->sense_len = vbr->in_hdr.sense_len; vbr->req->errors = vbr->in_hdr.errors; break; case REQ_TYPE_SPECIAL: vbr->req->errors = (error != 0); break; default: 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 = 0, in = 0; 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 (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(); } } sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->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 before the normal inhdr. */ if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) { sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96); sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, sizeof(vbr->in_hdr)); } sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, sizeof(vbr->status)); if (num) { if (rq_data_dir(vbr->req) == WRITE) { vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; out += num; } else { vbr->out_hdr.type |= VIRTIO_BLK_T_IN; in += num; } } if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 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 = q->queuedata; struct request *req; unsigned int issued = 0; while ((req = blk_peek_request(q)) != NULL) { 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; } blk_start_request(req); issued++; } if (issued) virtqueue_kick(vblk->vq); } /* 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; 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; return blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); } static int virtblk_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned 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_ioctl(disk->queue, disk, mode, cmd, (void __user *)data); } static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long param) { int ret; lock_kernel(); ret = virtblk_locked_ioctl(bdev, mode, cmd, param); unlock_kernel(); return ret; } /* 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 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 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 int __devinit virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk; struct request_queue *q; int err; u64 cap; u32 v, blk_size, sg_elems, opt_io_size; u16 min_io_size; u8 physical_block_exp, alignment_offset; 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); /* 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) + 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 = virtio_find_single_vq(vdev, blk_done, "requests"); 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; } q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); if (!q) { err = -ENOMEM; goto out_put_disk; } q->queuedata = vblk; 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++; /* configure queue flush support */ if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) blk_queue_flush(q, REQ_FLUSH); /* 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_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_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, offsetof(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_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, offsetof(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_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, offsetof(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_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, offsetof(struct virtio_blk_config, alignment_offset), &alignment_offset); if (!err && alignment_offset) blk_queue_alignment_offset(q, blk_size * alignment_offset); err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, offsetof(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_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, offsetof(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; return 0; out_del_disk: del_gendisk(vblk->disk); blk_cleanup_queue(vblk->disk->queue); out_put_disk: put_disk(vblk->disk); out_mempool: mempool_destroy(vblk->pool); out_free_vq: vdev->config->del_vqs(vdev); out_free_vblk: kfree(vblk); out: return err; } static void __devexit 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_vqs(vdev); kfree(vblk); } 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_FLUSH, VIRTIO_BLK_F_TOPOLOGY }; /* * virtio_blk causes spurious section mismatch warning by * simultaneously referring to a __devinit and a __devexit function. * Use __refdata to avoid this warning. */ static struct virtio_driver __refdata 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");