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         spinlock_t lock;
  25
  26         struct virtio_device *vdev;
  27         struct virtqueue *vq;
  28
  29         /* The disk structure for the kernel. */
  30         struct gendisk *disk;
  31
  32         /* Request tracking. */
  33         struct list_head reqs;
  34
  35         mempool_t *pool;
  36
  37         /* Process context for config space updates */
  38         struct work_struct config_work;
  39
  40         /* Lock for config space updates */
  41         struct mutex config_lock;
  42
  43         /* enable config space updates */
  44         bool config_enable;
  45
  46         /* What host tells us, plus 2 for header & tailer. */
  47         unsigned int sg_elems;
  48
  49         /* Ida index - used to track minor number allocations. */
  50         int index;
  51
  52         /* Scatterlist: can be too big for stack. */
  53         struct scatterlist sg[/*sg_elems*/];
  54 };
  55
  56 struct virtblk_req
  57 {
  58         struct list_head list;
  59         struct request *req;
  60         struct virtio_blk_outhdr out_hdr;
  61         struct virtio_scsi_inhdr in_hdr;
  62         u8 status;
  63 };
  64
  65 static void blk_done(struct virtqueue *vq)
  66 {
  67         struct virtio_blk *vblk = vq->vdev->priv;
  68         struct virtblk_req *vbr;
  69         unsigned int len;
  70         unsigned long flags;
  71
  72         spin_lock_irqsave(&vblk->lock, flags);
  73         while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
  74                 int error;
  75
  76                 switch (vbr->status) {
  77                 case VIRTIO_BLK_S_OK:
  78                         error = 0;
  79                         break;
  80                 case VIRTIO_BLK_S_UNSUPP:
  81                         error = -ENOTTY;
  82                         break;
  83                 default:
  84                         error = -EIO;
  85                         break;
  86                 }
  87
  88                 switch (vbr->req->cmd_type) {
  89                 case REQ_TYPE_BLOCK_PC:
  90                         vbr->req->resid_len = vbr->in_hdr.residual;
  91                         vbr->req->sense_len = vbr->in_hdr.sense_len;
  92                         vbr->req->errors = vbr->in_hdr.errors;
  93                         break;
  94                 case REQ_TYPE_SPECIAL:
  95                         vbr->req->errors = (error != 0);
  96                         break;
  97                 default:
  98                         break;
  99                 }
 100
 101                 __blk_end_request_all(vbr->req, error);
 102                 list_del(&vbr->list);
 103                 mempool_free(vbr, vblk->pool);
 104         }
 105         /* In case queue is stopped waiting for more buffers. */
 106         blk_start_queue(vblk->disk->queue);
 107         spin_unlock_irqrestore(&vblk->lock, flags);
 108 }
 109
 110 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
 111                    struct request *req)
 112 {
 113         unsigned long num, out = 0, in = 0;
 114         struct virtblk_req *vbr;
 115
 116         vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
 117         if (!vbr)
 118                 /* When another request finishes we'll try again. */
 119                 return false;
 120
 121         vbr->req = req;
 122
 123         if (req->cmd_flags & REQ_FLUSH) {
 124                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
 125                 vbr->out_hdr.sector = 0;
 126                 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 127         } else {
 128                 switch (req->cmd_type) {
 129                 case REQ_TYPE_FS:
 130                         vbr->out_hdr.type = 0;
 131                         vbr->out_hdr.sector = blk_rq_pos(vbr->req);
 132                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 133                         break;
 134                 case REQ_TYPE_BLOCK_PC:
 135                         vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
 136                         vbr->out_hdr.sector = 0;
 137                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 138                         break;
 139                 case REQ_TYPE_SPECIAL:
 140                         vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
 141                         vbr->out_hdr.sector = 0;
 142                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 143                         break;
 144                 default:
 145                         /* We don't put anything else in the queue. */
 146                         BUG();
 147                 }
 148         }
 149
 150         sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
 151
 152         /*
 153          * If this is a packet command we need a couple of additional headers.
 154          * Behind the normal outhdr we put a segment with the scsi command
 155          * block, and before the normal inhdr we put the sense data and the
 156          * inhdr with additional status information before the normal inhdr.
 157          */
 158         if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
 159                 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
 160
 161         num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
 162
 163         if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
 164                 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
 165                 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
 166                            sizeof(vbr->in_hdr));
 167         }
 168
 169         sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
 170                    sizeof(vbr->status));
 171
 172         if (num) {
 173                 if (rq_data_dir(vbr->req) == WRITE) {
 174                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
 175                         out += num;
 176                 } else {
 177                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
 178                         in += num;
 179                 }
 180         }
 181
 182         if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) {
 183                 mempool_free(vbr, vblk->pool);
 184                 return false;
 185         }
 186
 187         list_add_tail(&vbr->list, &vblk->reqs);
 188         return true;
 189 }
 190
 191 static void do_virtblk_request(struct request_queue *q)
 192 {
 193         struct virtio_blk *vblk = q->queuedata;
 194         struct request *req;
 195         unsigned int issued = 0;
 196
 197         while ((req = blk_peek_request(q)) != NULL) {
 198                 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
 199
 200                 /* If this request fails, stop queue and wait for something to
 201                    finish to restart it. */
 202                 if (!do_req(q, vblk, req)) {
 203                         blk_stop_queue(q);
 204                         break;
 205                 }
 206                 blk_start_request(req);
 207                 issued++;
 208         }
 209
 210         if (issued)
 211                 virtqueue_kick(vblk->vq);
 212 }
 213
 214 /* return id (s/n) string for *disk to *id_str
 215  */
 216 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 217 {
 218         struct virtio_blk *vblk = disk->private_data;
 219         struct request *req;
 220         struct bio *bio;
 221         int err;
 222
 223         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
 224                            GFP_KERNEL);
 225         if (IS_ERR(bio))
 226                 return PTR_ERR(bio);
 227
 228         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
 229         if (IS_ERR(req)) {
 230                 bio_put(bio);
 231                 return PTR_ERR(req);
 232         }
 233
 234         req->cmd_type = REQ_TYPE_SPECIAL;
 235         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
 236         blk_put_request(req);
 237
 238         return err;
 239 }
 240
 241 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 242                              unsigned int cmd, unsigned long data)
 243 {
 244         struct gendisk *disk = bdev->bd_disk;
 245         struct virtio_blk *vblk = disk->private_data;
 246
 247         /*
 248          * Only allow the generic SCSI ioctls if the host can support it.
 249          */
 250         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
 251                 return -ENOTTY;
 252
 253         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
 254                                   (void __user *)data);
 255 }
 256
 257 /* We provide getgeo only to please some old bootloader/partitioning tools */
 258 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 259 {
 260         struct virtio_blk *vblk = bd->bd_disk->private_data;
 261         struct virtio_blk_geometry vgeo;
 262         int err;
 263
 264         /* see if the host passed in geometry config */
 265         err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
 266                                 offsetof(struct virtio_blk_config, geometry),
 267                                 &vgeo);
 268
 269         if (!err) {
 270                 geo->heads = vgeo.heads;
 271                 geo->sectors = vgeo.sectors;
 272                 geo->cylinders = vgeo.cylinders;
 273         } else {
 274                 /* some standard values, similar to sd */
 275                 geo->heads = 1 << 6;
 276                 geo->sectors = 1 << 5;
 277                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 278         }
 279         return 0;
 280 }
 281
 282 static const struct block_device_operations virtblk_fops = {
 283         .ioctl  = virtblk_ioctl,
 284         .owner  = THIS_MODULE,
 285         .getgeo = virtblk_getgeo,
 286 };
 287
 288 static int index_to_minor(int index)
 289 {
 290         return index << PART_BITS;
 291 }
 292
 293 static int minor_to_index(int minor)
 294 {
 295         return minor >> PART_BITS;
 296 }
 297
 298 static ssize_t virtblk_serial_show(struct device *dev,
 299                                 struct device_attribute *attr, char *buf)
 300 {
 301         struct gendisk *disk = dev_to_disk(dev);
 302         int err;
 303
 304         /* sysfs gives us a PAGE_SIZE buffer */
 305         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 306
 307         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 308         err = virtblk_get_id(disk, buf);
 309         if (!err)
 310                 return strlen(buf);
 311
 312         if (err == -EIO) /* Unsupported? Make it empty. */
 313                 return 0;
 314
 315         return err;
 316 }
 317 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
 318
 319 static void virtblk_config_changed_work(struct work_struct *work)
 320 {
 321         struct virtio_blk *vblk =
 322                 container_of(work, struct virtio_blk, config_work);
 323         struct virtio_device *vdev = vblk->vdev;
 324         struct request_queue *q = vblk->disk->queue;
 325         char cap_str_2[10], cap_str_10[10];
 326         u64 capacity, size;
 327
 328         mutex_lock(&vblk->config_lock);
 329         if (!vblk->config_enable)
 330                 goto done;
 331
 332         /* Host must always specify the capacity. */
 333         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 334                           &capacity, sizeof(capacity));
 335
 336         /* If capacity is too big, truncate with warning. */
 337         if ((sector_t)capacity != capacity) {
 338                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 339                          (unsigned long long)capacity);
 340                 capacity = (sector_t)-1;
 341         }
 342
 343         size = capacity * queue_logical_block_size(q);
 344         string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 345         string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 346
 347         dev_notice(&vdev->dev,
 348                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
 349                   (unsigned long long)capacity,
 350                   queue_logical_block_size(q),
 351                   cap_str_10, cap_str_2);
 352
 353         set_capacity(vblk->disk, capacity);
 354         revalidate_disk(vblk->disk);
 355 done:
 356         mutex_unlock(&vblk->config_lock);
 357 }
 358
 359 static void virtblk_config_changed(struct virtio_device *vdev)
 360 {
 361         struct virtio_blk *vblk = vdev->priv;
 362
 363         queue_work(virtblk_wq, &vblk->config_work);
 364 }
 365
 366 static int init_vq(struct virtio_blk *vblk)
 367 {
 368         int err = 0;
 369
 370         /* We expect one virtqueue, for output. */
 371         vblk->vq = virtio_find_single_vq(vblk->vdev, blk_done, "requests");
 372         if (IS_ERR(vblk->vq))
 373                 err = PTR_ERR(vblk->vq);
 374
 375         return err;
 376 }
 377
 378 /*
 379  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 380  * virtio blk but don't ever use it for any new driver.
 381  */
 382 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 383 {
 384         const int base = 'z' - 'a' + 1;
 385         char *begin = buf + strlen(prefix);
 386         char *end = buf + buflen;
 387         char *p;
 388         int unit;
 389
 390         p = end - 1;
 391         *p = '\0';
 392         unit = base;
 393         do {
 394                 if (p == begin)
 395                         return -EINVAL;
 396                 *--p = 'a' + (index % unit);
 397                 index = (index / unit) - 1;
 398         } while (index >= 0);
 399
 400         memmove(begin, p, end - p);
 401         memcpy(buf, prefix, strlen(prefix));
 402
 403         return 0;
 404 }
 405
 406 static int __devinit virtblk_probe(struct virtio_device *vdev)
 407 {
 408         struct virtio_blk *vblk;
 409         struct request_queue *q;
 410         int err, index;
 411         u64 cap;
 412         u32 v, blk_size, sg_elems, opt_io_size;
 413         u16 min_io_size;
 414         u8 physical_block_exp, alignment_offset;
 415
 416         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 417                              GFP_KERNEL);
 418         if (err < 0)
 419                 goto out;
 420         index = err;
 421
 422         /* We need to know how many segments before we allocate. */
 423         err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
 424                                 offsetof(struct virtio_blk_config, seg_max),
 425                                 &sg_elems);
 426
 427         /* We need at least one SG element, whatever they say. */
 428         if (err || !sg_elems)
 429                 sg_elems = 1;
 430
 431         /* We need an extra sg elements at head and tail. */
 432         sg_elems += 2;
 433         vdev->priv = vblk = kmalloc(sizeof(*vblk) +
 434                                     sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
 435         if (!vblk) {
 436                 err = -ENOMEM;
 437                 goto out_free_index;
 438         }
 439
 440         INIT_LIST_HEAD(&vblk->reqs);
 441         spin_lock_init(&vblk->lock);
 442         vblk->vdev = vdev;
 443         vblk->sg_elems = sg_elems;
 444         sg_init_table(vblk->sg, vblk->sg_elems);
 445         mutex_init(&vblk->config_lock);
 446         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 447         vblk->config_enable = true;
 448
 449         err = init_vq(vblk);
 450         if (err)
 451                 goto out_free_vblk;
 452
 453         vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
 454         if (!vblk->pool) {
 455                 err = -ENOMEM;
 456                 goto out_free_vq;
 457         }
 458
 459         /* FIXME: How many partitions?  How long is a piece of string? */
 460         vblk->disk = alloc_disk(1 << PART_BITS);
 461         if (!vblk->disk) {
 462                 err = -ENOMEM;
 463                 goto out_mempool;
 464         }
 465
 466         q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
 467         if (!q) {
 468                 err = -ENOMEM;
 469                 goto out_put_disk;
 470         }
 471
 472         q->queuedata = vblk;
 473
 474         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 475
 476         vblk->disk->major = major;
 477         vblk->disk->first_minor = index_to_minor(index);
 478         vblk->disk->private_data = vblk;
 479         vblk->disk->fops = &virtblk_fops;
 480         vblk->disk->driverfs_dev = &vdev->dev;
 481         vblk->index = index;
 482
 483         /* configure queue flush support */
 484         if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
 485                 blk_queue_flush(q, REQ_FLUSH);
 486
 487         /* If disk is read-only in the host, the guest should obey */
 488         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 489                 set_disk_ro(vblk->disk, 1);
 490
 491         /* Host must always specify the capacity. */
 492         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 493                           &cap, sizeof(cap));
 494
 495         /* If capacity is too big, truncate with warning. */
 496         if ((sector_t)cap != cap) {
 497                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 498                          (unsigned long long)cap);
 499                 cap = (sector_t)-1;
 500         }
 501         set_capacity(vblk->disk, cap);
 502
 503         /* We can handle whatever the host told us to handle. */
 504         blk_queue_max_segments(q, vblk->sg_elems-2);
 505
 506         /* No need to bounce any requests */
 507         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
 508
 509         /* No real sector limit. */
 510         blk_queue_max_hw_sectors(q, -1U);
 511
 512         /* Host can optionally specify maximum segment size and number of
 513          * segments. */
 514         err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
 515                                 offsetof(struct virtio_blk_config, size_max),
 516                                 &v);
 517         if (!err)
 518                 blk_queue_max_segment_size(q, v);
 519         else
 520                 blk_queue_max_segment_size(q, -1U);
 521
 522         /* Host can optionally specify the block size of the device */
 523         err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
 524                                 offsetof(struct virtio_blk_config, blk_size),
 525                                 &blk_size);
 526         if (!err)
 527                 blk_queue_logical_block_size(q, blk_size);
 528         else
 529                 blk_size = queue_logical_block_size(q);
 530
 531         /* Use topology information if available */
 532         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 533                         offsetof(struct virtio_blk_config, physical_block_exp),
 534                         &physical_block_exp);
 535         if (!err && physical_block_exp)
 536                 blk_queue_physical_block_size(q,
 537                                 blk_size * (1 << physical_block_exp));
 538
 539         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 540                         offsetof(struct virtio_blk_config, alignment_offset),
 541                         &alignment_offset);
 542         if (!err && alignment_offset)
 543                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
 544
 545         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 546                         offsetof(struct virtio_blk_config, min_io_size),
 547                         &min_io_size);
 548         if (!err && min_io_size)
 549                 blk_queue_io_min(q, blk_size * min_io_size);
 550
 551         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 552                         offsetof(struct virtio_blk_config, opt_io_size),
 553                         &opt_io_size);
 554         if (!err && opt_io_size)
 555                 blk_queue_io_opt(q, blk_size * opt_io_size);
 556
 557
 558         add_disk(vblk->disk);
 559         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
 560         if (err)
 561                 goto out_del_disk;
 562
 563         return 0;
 564
 565 out_del_disk:
 566         del_gendisk(vblk->disk);
 567         blk_cleanup_queue(vblk->disk->queue);
 568 out_put_disk:
 569         put_disk(vblk->disk);
 570 out_mempool:
 571         mempool_destroy(vblk->pool);
 572 out_free_vq:
 573         vdev->config->del_vqs(vdev);
 574 out_free_vblk:
 575         kfree(vblk);
 576 out_free_index:
 577         ida_simple_remove(&vd_index_ida, index);
 578 out:
 579         return err;
 580 }
 581
 582 static void __devexit virtblk_remove(struct virtio_device *vdev)
 583 {
 584         struct virtio_blk *vblk = vdev->priv;
 585         int index = vblk->index;
 586
 587         /* Prevent config work handler from accessing the device. */
 588         mutex_lock(&vblk->config_lock);
 589         vblk->config_enable = false;
 590         mutex_unlock(&vblk->config_lock);
 591
 592         /* Nothing should be pending. */
 593         BUG_ON(!list_empty(&vblk->reqs));
 594
 595         /* Stop all the virtqueues. */
 596         vdev->config->reset(vdev);
 597
 598         flush_work(&vblk->config_work);
 599
 600         del_gendisk(vblk->disk);
 601         blk_cleanup_queue(vblk->disk->queue);
 602         put_disk(vblk->disk);
 603         mempool_destroy(vblk->pool);
 604         vdev->config->del_vqs(vdev);
 605         kfree(vblk);
 606         ida_simple_remove(&vd_index_ida, index);
 607 }
 608
 609 #ifdef CONFIG_PM
 610 static int virtblk_freeze(struct virtio_device *vdev)
 611 {
 612         struct virtio_blk *vblk = vdev->priv;
 613
 614         /* Ensure we don't receive any more interrupts */
 615         vdev->config->reset(vdev);
 616
 617         /* Prevent config work handler from accessing the device. */
 618         mutex_lock(&vblk->config_lock);
 619         vblk->config_enable = false;
 620         mutex_unlock(&vblk->config_lock);
 621
 622         flush_work(&vblk->config_work);
 623
 624         spin_lock_irq(vblk->disk->queue->queue_lock);
 625         blk_stop_queue(vblk->disk->queue);
 626         spin_unlock_irq(vblk->disk->queue->queue_lock);
 627         blk_sync_queue(vblk->disk->queue);
 628
 629         vdev->config->del_vqs(vdev);
 630         return 0;
 631 }
 632
 633 static int virtblk_restore(struct virtio_device *vdev)
 634 {
 635         struct virtio_blk *vblk = vdev->priv;
 636         int ret;
 637
 638         vblk->config_enable = true;
 639         ret = init_vq(vdev->priv);
 640         if (!ret) {
 641                 spin_lock_irq(vblk->disk->queue->queue_lock);
 642                 blk_start_queue(vblk->disk->queue);
 643                 spin_unlock_irq(vblk->disk->queue->queue_lock);
 644         }
 645         return ret;
 646 }
 647 #endif
 648
 649 static const struct virtio_device_id id_table[] = {
 650         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 651         { 0 },
 652 };
 653
 654 static unsigned int features[] = {
 655         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
 656         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
 657         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
 658 };
 659
 660 /*
 661  * virtio_blk causes spurious section mismatch warning by
 662  * simultaneously referring to a __devinit and a __devexit function.
 663  * Use __refdata to avoid this warning.
 664  */
 665 static struct virtio_driver __refdata virtio_blk = {
 666         .feature_table          = features,
 667         .feature_table_size     = ARRAY_SIZE(features),
 668         .driver.name            = KBUILD_MODNAME,
 669         .driver.owner           = THIS_MODULE,
 670         .id_table               = id_table,
 671         .probe                  = virtblk_probe,
 672         .remove                 = __devexit_p(virtblk_remove),
 673         .config_changed         = virtblk_config_changed,
 674 #ifdef CONFIG_PM
 675         .freeze                 = virtblk_freeze,
 676         .restore                = virtblk_restore,
 677 #endif
 678 };
 679
 680 static int __init init(void)
 681 {
 682         int error;
 683
 684         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
 685         if (!virtblk_wq)
 686                 return -ENOMEM;
 687
 688         major = register_blkdev(0, "virtblk");
 689         if (major < 0) {
 690                 error = major;
 691                 goto out_destroy_workqueue;
 692         }
 693
 694         error = register_virtio_driver(&virtio_blk);
 695         if (error)
 696                 goto out_unregister_blkdev;
 697         return 0;
 698
 699 out_unregister_blkdev:
 700         unregister_blkdev(major, "virtblk");
 701 out_destroy_workqueue:
 702         destroy_workqueue(virtblk_wq);
 703         return error;
 704 }
 705
 706 static void __exit fini(void)
 707 {
 708         unregister_blkdev(major, "virtblk");
 709         unregister_virtio_driver(&virtio_blk);
 710         destroy_workqueue(virtblk_wq);
 711 }
 712 module_init(init);
 713 module_exit(fini);
 714
 715 MODULE_DEVICE_TABLE(virtio, id_table);
 716 MODULE_DESCRIPTION("Virtio block driver");
 717 MODULE_LICENSE("GPL");