drivers/block/virtio_blk.c

   1 //#define DEBUG
   2 #include <linux/spinlock.h>
   3 #include <linux/slab.h>
   4 #include <linux/blkdev.h>
   5 #include <linux/hdreg.h>
   6 #include <linux/module.h>
   7 #include <linux/mutex.h>
   8 #include <linux/virtio.h>
   9 #include <linux/virtio_blk.h>
  10 #include <linux/scatterlist.h>
  11 #include <linux/string_helpers.h>
  12 #include <scsi/scsi_cmnd.h>
  13 #include <linux/idr.h>
  14
  15 #define PART_BITS 4
  16
  17 static int major;
  18 static DEFINE_IDA(vd_index_ida);
  19
  20 struct workqueue_struct *virtblk_wq;
  21
  22 struct virtio_blk
  23 {
  24         struct virtio_device *vdev;
  25         struct virtqueue *vq;
  26
  27         /* The disk structure for the kernel. */
  28         struct gendisk *disk;
  29
  30         mempool_t *pool;
  31
  32         /* Process context for config space updates */
  33         struct work_struct config_work;
  34
  35         /* Lock for config space updates */
  36         struct mutex config_lock;
  37
  38         /* enable config space updates */
  39         bool config_enable;
  40
  41         /* What host tells us, plus 2 for header & tailer. */
  42         unsigned int sg_elems;
  43
  44         /* Ida index - used to track minor number allocations. */
  45         int index;
  46
  47         /* Scatterlist: can be too big for stack. */
  48         struct scatterlist sg[/*sg_elems*/];
  49 };
  50
  51 struct virtblk_req
  52 {
  53         struct request *req;
  54         struct virtio_blk_outhdr out_hdr;
  55         struct virtio_scsi_inhdr in_hdr;
  56         u8 status;
  57 };
  58
  59 static void blk_done(struct virtqueue *vq)
  60 {
  61         struct virtio_blk *vblk = vq->vdev->priv;
  62         struct virtblk_req *vbr;
  63         unsigned int len;
  64         unsigned long flags;
  65
  66         spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
  67         while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
  68                 int error;
  69
  70                 switch (vbr->status) {
  71                 case VIRTIO_BLK_S_OK:
  72                         error = 0;
  73                         break;
  74                 case VIRTIO_BLK_S_UNSUPP:
  75                         error = -ENOTTY;
  76                         break;
  77                 default:
  78                         error = -EIO;
  79                         break;
  80                 }
  81
  82                 switch (vbr->req->cmd_type) {
  83                 case REQ_TYPE_BLOCK_PC:
  84                         vbr->req->resid_len = vbr->in_hdr.residual;
  85                         vbr->req->sense_len = vbr->in_hdr.sense_len;
  86                         vbr->req->errors = vbr->in_hdr.errors;
  87                         break;
  88                 case REQ_TYPE_SPECIAL:
  89                         vbr->req->errors = (error != 0);
  90                         break;
  91                 default:
  92                         break;
  93                 }
  94
  95                 __blk_end_request_all(vbr->req, error);
  96                 mempool_free(vbr, vblk->pool);
  97         }
  98         /* In case queue is stopped waiting for more buffers. */
  99         blk_start_queue(vblk->disk->queue);
 100         spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
 101 }
 102
 103 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
 104                    struct request *req)
 105 {
 106         unsigned long num, out = 0, in = 0;
 107         struct virtblk_req *vbr;
 108
 109         vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
 110         if (!vbr)
 111                 /* When another request finishes we'll try again. */
 112                 return false;
 113
 114         vbr->req = req;
 115
 116         if (req->cmd_flags & REQ_FLUSH) {
 117                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
 118                 vbr->out_hdr.sector = 0;
 119                 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 120         } else {
 121                 switch (req->cmd_type) {
 122                 case REQ_TYPE_FS:
 123                         vbr->out_hdr.type = 0;
 124                         vbr->out_hdr.sector = blk_rq_pos(vbr->req);
 125                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 126                         break;
 127                 case REQ_TYPE_BLOCK_PC:
 128                         vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
 129                         vbr->out_hdr.sector = 0;
 130                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 131                         break;
 132                 case REQ_TYPE_SPECIAL:
 133                         vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
 134                         vbr->out_hdr.sector = 0;
 135                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 136                         break;
 137                 default:
 138                         /* We don't put anything else in the queue. */
 139                         BUG();
 140                 }
 141         }
 142
 143         sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
 144
 145         /*
 146          * If this is a packet command we need a couple of additional headers.
 147          * Behind the normal outhdr we put a segment with the scsi command
 148          * block, and before the normal inhdr we put the sense data and the
 149          * inhdr with additional status information before the normal inhdr.
 150          */
 151         if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
 152                 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
 153
 154         num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
 155
 156         if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
 157                 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
 158                 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
 159                            sizeof(vbr->in_hdr));
 160         }
 161
 162         sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
 163                    sizeof(vbr->status));
 164
 165         if (num) {
 166                 if (rq_data_dir(vbr->req) == WRITE) {
 167                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
 168                         out += num;
 169                 } else {
 170                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
 171                         in += num;
 172                 }
 173         }
 174
 175         if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) {
 176                 mempool_free(vbr, vblk->pool);
 177                 return false;
 178         }
 179
 180         return true;
 181 }
 182
 183 static void do_virtblk_request(struct request_queue *q)
 184 {
 185         struct virtio_blk *vblk = q->queuedata;
 186         struct request *req;
 187         unsigned int issued = 0;
 188
 189         while ((req = blk_peek_request(q)) != NULL) {
 190                 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
 191
 192                 /* If this request fails, stop queue and wait for something to
 193                    finish to restart it. */
 194                 if (!do_req(q, vblk, req)) {
 195                         blk_stop_queue(q);
 196                         break;
 197                 }
 198                 blk_start_request(req);
 199                 issued++;
 200         }
 201
 202         if (issued)
 203                 virtqueue_kick(vblk->vq);
 204 }
 205
 206 /* return id (s/n) string for *disk to *id_str
 207  */
 208 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 209 {
 210         struct virtio_blk *vblk = disk->private_data;
 211         struct request *req;
 212         struct bio *bio;
 213         int err;
 214
 215         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
 216                            GFP_KERNEL);
 217         if (IS_ERR(bio))
 218                 return PTR_ERR(bio);
 219
 220         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
 221         if (IS_ERR(req)) {
 222                 bio_put(bio);
 223                 return PTR_ERR(req);
 224         }
 225
 226         req->cmd_type = REQ_TYPE_SPECIAL;
 227         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
 228         blk_put_request(req);
 229
 230         return err;
 231 }
 232
 233 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 234                              unsigned int cmd, unsigned long data)
 235 {
 236         struct gendisk *disk = bdev->bd_disk;
 237         struct virtio_blk *vblk = disk->private_data;
 238
 239         /*
 240          * Only allow the generic SCSI ioctls if the host can support it.
 241          */
 242         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
 243                 return -ENOTTY;
 244
 245         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
 246                                   (void __user *)data);
 247 }
 248
 249 /* We provide getgeo only to please some old bootloader/partitioning tools */
 250 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 251 {
 252         struct virtio_blk *vblk = bd->bd_disk->private_data;
 253         struct virtio_blk_geometry vgeo;
 254         int err;
 255
 256         /* see if the host passed in geometry config */
 257         err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
 258                                 offsetof(struct virtio_blk_config, geometry),
 259                                 &vgeo);
 260
 261         if (!err) {
 262                 geo->heads = vgeo.heads;
 263                 geo->sectors = vgeo.sectors;
 264                 geo->cylinders = vgeo.cylinders;
 265         } else {
 266                 /* some standard values, similar to sd */
 267                 geo->heads = 1 << 6;
 268                 geo->sectors = 1 << 5;
 269                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 270         }
 271         return 0;
 272 }
 273
 274 static const struct block_device_operations virtblk_fops = {
 275         .ioctl  = virtblk_ioctl,
 276         .owner  = THIS_MODULE,
 277         .getgeo = virtblk_getgeo,
 278 };
 279
 280 static int index_to_minor(int index)
 281 {
 282         return index << PART_BITS;
 283 }
 284
 285 static int minor_to_index(int minor)
 286 {
 287         return minor >> PART_BITS;
 288 }
 289
 290 static ssize_t virtblk_serial_show(struct device *dev,
 291                                 struct device_attribute *attr, char *buf)
 292 {
 293         struct gendisk *disk = dev_to_disk(dev);
 294         int err;
 295
 296         /* sysfs gives us a PAGE_SIZE buffer */
 297         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 298
 299         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 300         err = virtblk_get_id(disk, buf);
 301         if (!err)
 302                 return strlen(buf);
 303
 304         if (err == -EIO) /* Unsupported? Make it empty. */
 305                 return 0;
 306
 307         return err;
 308 }
 309 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
 310
 311 static void virtblk_config_changed_work(struct work_struct *work)
 312 {
 313         struct virtio_blk *vblk =
 314                 container_of(work, struct virtio_blk, config_work);
 315         struct virtio_device *vdev = vblk->vdev;
 316         struct request_queue *q = vblk->disk->queue;
 317         char cap_str_2[10], cap_str_10[10];
 318         u64 capacity, size;
 319
 320         mutex_lock(&vblk->config_lock);
 321         if (!vblk->config_enable)
 322                 goto done;
 323
 324         /* Host must always specify the capacity. */
 325         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 326                           &capacity, sizeof(capacity));
 327
 328         /* If capacity is too big, truncate with warning. */
 329         if ((sector_t)capacity != capacity) {
 330                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 331                          (unsigned long long)capacity);
 332                 capacity = (sector_t)-1;
 333         }
 334
 335         size = capacity * queue_logical_block_size(q);
 336         string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 337         string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 338
 339         dev_notice(&vdev->dev,
 340                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
 341                   (unsigned long long)capacity,
 342                   queue_logical_block_size(q),
 343                   cap_str_10, cap_str_2);
 344
 345         set_capacity(vblk->disk, capacity);
 346         revalidate_disk(vblk->disk);
 347 done:
 348         mutex_unlock(&vblk->config_lock);
 349 }
 350
 351 static void virtblk_config_changed(struct virtio_device *vdev)
 352 {
 353         struct virtio_blk *vblk = vdev->priv;
 354
 355         queue_work(virtblk_wq, &vblk->config_work);
 356 }
 357
 358 static int init_vq(struct virtio_blk *vblk)
 359 {
 360         int err = 0;
 361
 362         /* We expect one virtqueue, for output. */
 363         vblk->vq = virtio_find_single_vq(vblk->vdev, blk_done, "requests");
 364         if (IS_ERR(vblk->vq))
 365                 err = PTR_ERR(vblk->vq);
 366
 367         return err;
 368 }
 369
 370 /*
 371  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 372  * virtio blk but don't ever use it for any new driver.
 373  */
 374 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 375 {
 376         const int base = 'z' - 'a' + 1;
 377         char *begin = buf + strlen(prefix);
 378         char *end = buf + buflen;
 379         char *p;
 380         int unit;
 381
 382         p = end - 1;
 383         *p = '\0';
 384         unit = base;
 385         do {
 386                 if (p == begin)
 387                         return -EINVAL;
 388                 *--p = 'a' + (index % unit);
 389                 index = (index / unit) - 1;
 390         } while (index >= 0);
 391
 392         memmove(begin, p, end - p);
 393         memcpy(buf, prefix, strlen(prefix));
 394
 395         return 0;
 396 }
 397
 398 static int __devinit virtblk_probe(struct virtio_device *vdev)
 399 {
 400         struct virtio_blk *vblk;
 401         struct request_queue *q;
 402         int err, index;
 403         u64 cap;
 404         u32 v, blk_size, sg_elems, opt_io_size;
 405         u16 min_io_size;
 406         u8 physical_block_exp, alignment_offset;
 407
 408         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 409                              GFP_KERNEL);
 410         if (err < 0)
 411                 goto out;
 412         index = err;
 413
 414         /* We need to know how many segments before we allocate. */
 415         err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
 416                                 offsetof(struct virtio_blk_config, seg_max),
 417                                 &sg_elems);
 418
 419         /* We need at least one SG element, whatever they say. */
 420         if (err || !sg_elems)
 421                 sg_elems = 1;
 422
 423         /* We need an extra sg elements at head and tail. */
 424         sg_elems += 2;
 425         vdev->priv = vblk = kmalloc(sizeof(*vblk) +
 426                                     sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
 427         if (!vblk) {
 428                 err = -ENOMEM;
 429                 goto out_free_index;
 430         }
 431
 432         vblk->vdev = vdev;
 433         vblk->sg_elems = sg_elems;
 434         sg_init_table(vblk->sg, vblk->sg_elems);
 435         mutex_init(&vblk->config_lock);
 436         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 437         vblk->config_enable = true;
 438
 439         err = init_vq(vblk);
 440         if (err)
 441                 goto out_free_vblk;
 442
 443         vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
 444         if (!vblk->pool) {
 445                 err = -ENOMEM;
 446                 goto out_free_vq;
 447         }
 448
 449         /* FIXME: How many partitions?  How long is a piece of string? */
 450         vblk->disk = alloc_disk(1 << PART_BITS);
 451         if (!vblk->disk) {
 452                 err = -ENOMEM;
 453                 goto out_mempool;
 454         }
 455
 456         q = vblk->disk->queue = blk_init_queue(do_virtblk_request, NULL);
 457         if (!q) {
 458                 err = -ENOMEM;
 459                 goto out_put_disk;
 460         }
 461
 462         q->queuedata = vblk;
 463
 464         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 465
 466         vblk->disk->major = major;
 467         vblk->disk->first_minor = index_to_minor(index);
 468         vblk->disk->private_data = vblk;
 469         vblk->disk->fops = &virtblk_fops;
 470         vblk->disk->driverfs_dev = &vdev->dev;
 471         vblk->index = index;
 472
 473         /* configure queue flush support */
 474         if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
 475                 blk_queue_flush(q, REQ_FLUSH);
 476
 477         /* If disk is read-only in the host, the guest should obey */
 478         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 479                 set_disk_ro(vblk->disk, 1);
 480
 481         /* Host must always specify the capacity. */
 482         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 483                           &cap, sizeof(cap));
 484
 485         /* If capacity is too big, truncate with warning. */
 486         if ((sector_t)cap != cap) {
 487                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 488                          (unsigned long long)cap);
 489                 cap = (sector_t)-1;
 490         }
 491         set_capacity(vblk->disk, cap);
 492
 493         /* We can handle whatever the host told us to handle. */
 494         blk_queue_max_segments(q, vblk->sg_elems-2);
 495
 496         /* No need to bounce any requests */
 497         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
 498
 499         /* No real sector limit. */
 500         blk_queue_max_hw_sectors(q, -1U);
 501
 502         /* Host can optionally specify maximum segment size and number of
 503          * segments. */
 504         err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
 505                                 offsetof(struct virtio_blk_config, size_max),
 506                                 &v);
 507         if (!err)
 508                 blk_queue_max_segment_size(q, v);
 509         else
 510                 blk_queue_max_segment_size(q, -1U);
 511
 512         /* Host can optionally specify the block size of the device */
 513         err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
 514                                 offsetof(struct virtio_blk_config, blk_size),
 515                                 &blk_size);
 516         if (!err)
 517                 blk_queue_logical_block_size(q, blk_size);
 518         else
 519                 blk_size = queue_logical_block_size(q);
 520
 521         /* Use topology information if available */
 522         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 523                         offsetof(struct virtio_blk_config, physical_block_exp),
 524                         &physical_block_exp);
 525         if (!err && physical_block_exp)
 526                 blk_queue_physical_block_size(q,
 527                                 blk_size * (1 << physical_block_exp));
 528
 529         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 530                         offsetof(struct virtio_blk_config, alignment_offset),
 531                         &alignment_offset);
 532         if (!err && alignment_offset)
 533                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
 534
 535         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 536                         offsetof(struct virtio_blk_config, min_io_size),
 537                         &min_io_size);
 538         if (!err && min_io_size)
 539                 blk_queue_io_min(q, blk_size * min_io_size);
 540
 541         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 542                         offsetof(struct virtio_blk_config, opt_io_size),
 543                         &opt_io_size);
 544         if (!err && opt_io_size)
 545                 blk_queue_io_opt(q, blk_size * opt_io_size);
 546
 547
 548         add_disk(vblk->disk);
 549         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
 550         if (err)
 551                 goto out_del_disk;
 552
 553         return 0;
 554
 555 out_del_disk:
 556         del_gendisk(vblk->disk);
 557         blk_cleanup_queue(vblk->disk->queue);
 558 out_put_disk:
 559         put_disk(vblk->disk);
 560 out_mempool:
 561         mempool_destroy(vblk->pool);
 562 out_free_vq:
 563         vdev->config->del_vqs(vdev);
 564 out_free_vblk:
 565         kfree(vblk);
 566 out_free_index:
 567         ida_simple_remove(&vd_index_ida, index);
 568 out:
 569         return err;
 570 }
 571
 572 static void __devexit virtblk_remove(struct virtio_device *vdev)
 573 {
 574         struct virtio_blk *vblk = vdev->priv;
 575         int index = vblk->index;
 576         int refc;
 577
 578         /* Prevent config work handler from accessing the device. */
 579         mutex_lock(&vblk->config_lock);
 580         vblk->config_enable = false;
 581         mutex_unlock(&vblk->config_lock);
 582
 583         del_gendisk(vblk->disk);
 584         blk_cleanup_queue(vblk->disk->queue);
 585
 586         /* Stop all the virtqueues. */
 587         vdev->config->reset(vdev);
 588
 589         flush_work(&vblk->config_work);
 590
 591         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
 592         put_disk(vblk->disk);
 593         mempool_destroy(vblk->pool);
 594         vdev->config->del_vqs(vdev);
 595         kfree(vblk);
 596
 597         /* Only free device id if we don't have any users */
 598         if (refc == 1)
 599                 ida_simple_remove(&vd_index_ida, index);
 600 }
 601
 602 #ifdef CONFIG_PM
 603 static int virtblk_freeze(struct virtio_device *vdev)
 604 {
 605         struct virtio_blk *vblk = vdev->priv;
 606
 607         /* Ensure we don't receive any more interrupts */
 608         vdev->config->reset(vdev);
 609
 610         /* Prevent config work handler from accessing the device. */
 611         mutex_lock(&vblk->config_lock);
 612         vblk->config_enable = false;
 613         mutex_unlock(&vblk->config_lock);
 614
 615         flush_work(&vblk->config_work);
 616
 617         spin_lock_irq(vblk->disk->queue->queue_lock);
 618         blk_stop_queue(vblk->disk->queue);
 619         spin_unlock_irq(vblk->disk->queue->queue_lock);
 620         blk_sync_queue(vblk->disk->queue);
 621
 622         vdev->config->del_vqs(vdev);
 623         return 0;
 624 }
 625
 626 static int virtblk_restore(struct virtio_device *vdev)
 627 {
 628         struct virtio_blk *vblk = vdev->priv;
 629         int ret;
 630
 631         vblk->config_enable = true;
 632         ret = init_vq(vdev->priv);
 633         if (!ret) {
 634                 spin_lock_irq(vblk->disk->queue->queue_lock);
 635                 blk_start_queue(vblk->disk->queue);
 636                 spin_unlock_irq(vblk->disk->queue->queue_lock);
 637         }
 638         return ret;
 639 }
 640 #endif
 641
 642 static const struct virtio_device_id id_table[] = {
 643         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 644         { 0 },
 645 };
 646
 647 static unsigned int features[] = {
 648         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
 649         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
 650         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
 651 };
 652
 653 /*
 654  * virtio_blk causes spurious section mismatch warning by
 655  * simultaneously referring to a __devinit and a __devexit function.
 656  * Use __refdata to avoid this warning.
 657  */
 658 static struct virtio_driver __refdata virtio_blk = {
 659         .feature_table          = features,
 660         .feature_table_size     = ARRAY_SIZE(features),
 661         .driver.name            = KBUILD_MODNAME,
 662         .driver.owner           = THIS_MODULE,
 663         .id_table               = id_table,
 664         .probe                  = virtblk_probe,
 665         .remove                 = __devexit_p(virtblk_remove),
 666         .config_changed         = virtblk_config_changed,
 667 #ifdef CONFIG_PM
 668         .freeze                 = virtblk_freeze,
 669         .restore                = virtblk_restore,
 670 #endif
 671 };
 672
 673 static int __init init(void)
 674 {
 675         int error;
 676
 677         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
 678         if (!virtblk_wq)
 679                 return -ENOMEM;
 680
 681         major = register_blkdev(0, "virtblk");
 682         if (major < 0) {
 683                 error = major;
 684                 goto out_destroy_workqueue;
 685         }
 686
 687         error = register_virtio_driver(&virtio_blk);
 688         if (error)
 689                 goto out_unregister_blkdev;
 690         return 0;
 691
 692 out_unregister_blkdev:
 693         unregister_blkdev(major, "virtblk");
 694 out_destroy_workqueue:
 695         destroy_workqueue(virtblk_wq);
 696         return error;
 697 }
 698
 699 static void __exit fini(void)
 700 {
 701         unregister_blkdev(major, "virtblk");
 702         unregister_virtio_driver(&virtio_blk);
 703         destroy_workqueue(virtblk_wq);
 704 }
 705 module_init(init);
 706 module_exit(fini);
 707
 708 MODULE_DEVICE_TABLE(virtio, id_table);
 709 MODULE_DESCRIPTION("Virtio block driver");
 710 MODULE_LICENSE("GPL");