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 bool use_bio;
  18 module_param(use_bio, bool, S_IRUGO);
  19
  20 static int major;
  21 static DEFINE_IDA(vd_index_ida);
  22
  23 static struct workqueue_struct *virtblk_wq;
  24
  25 struct virtio_blk
  26 {
  27         struct virtio_device *vdev;
  28         struct virtqueue *vq;
  29         wait_queue_head_t queue_wait;
  30
  31         /* The disk structure for the kernel. */
  32         struct gendisk *disk;
  33
  34         mempool_t *pool;
  35
  36         /* Process context for config space updates */
  37         struct work_struct config_work;
  38
  39         /* Lock for config space updates */
  40         struct mutex config_lock;
  41
  42         /* enable config space updates */
  43         bool config_enable;
  44
  45         /* What host tells us, plus 2 for header & tailer. */
  46         unsigned int sg_elems;
  47
  48         /* Ida index - used to track minor number allocations. */
  49         int index;
  50
  51         /* Scatterlist: can be too big for stack. */
  52         struct scatterlist sg[/*sg_elems*/];
  53 };
  54
  55 struct virtblk_req
  56 {
  57         struct request *req;
  58         struct bio *bio;
  59         struct virtio_blk_outhdr out_hdr;
  60         struct virtio_scsi_inhdr in_hdr;
  61         struct work_struct work;
  62         struct virtio_blk *vblk;
  63         int flags;
  64         u8 status;
  65         struct scatterlist sg[];
  66 };
  67
  68 enum {
  69         VBLK_IS_FLUSH           = 1,
  70         VBLK_REQ_FLUSH          = 2,
  71         VBLK_REQ_DATA           = 4,
  72         VBLK_REQ_FUA            = 8,
  73 };
  74
  75 static inline int virtblk_result(struct virtblk_req *vbr)
  76 {
  77         switch (vbr->status) {
  78         case VIRTIO_BLK_S_OK:
  79                 return 0;
  80         case VIRTIO_BLK_S_UNSUPP:
  81                 return -ENOTTY;
  82         default:
  83                 return -EIO;
  84         }
  85 }
  86
  87 static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
  88                                                     gfp_t gfp_mask)
  89 {
  90         struct virtblk_req *vbr;
  91
  92         vbr = mempool_alloc(vblk->pool, gfp_mask);
  93         if (!vbr)
  94                 return NULL;
  95
  96         vbr->vblk = vblk;
  97         if (use_bio)
  98                 sg_init_table(vbr->sg, vblk->sg_elems);
  99
 100         return vbr;
 101 }
 102
 103 static int __virtblk_add_req(struct virtqueue *vq,
 104                              struct virtblk_req *vbr,
 105                              struct scatterlist *data_sg,
 106                              bool have_data)
 107 {
 108         struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
 109         unsigned int num_out = 0, num_in = 0;
 110         int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
 111
 112         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 113         sgs[num_out++] = &hdr;
 114
 115         /*
 116          * If this is a packet command we need a couple of additional headers.
 117          * Behind the normal outhdr we put a segment with the scsi command
 118          * block, and before the normal inhdr we put the sense data and the
 119          * inhdr with additional status information.
 120          */
 121         if (type == VIRTIO_BLK_T_SCSI_CMD) {
 122                 sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
 123                 sgs[num_out++] = &cmd;
 124         }
 125
 126         if (have_data) {
 127                 if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
 128                         sgs[num_out++] = data_sg;
 129                 else
 130                         sgs[num_out + num_in++] = data_sg;
 131         }
 132
 133         if (type == VIRTIO_BLK_T_SCSI_CMD) {
 134                 sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
 135                 sgs[num_out + num_in++] = &sense;
 136                 sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
 137                 sgs[num_out + num_in++] = &inhdr;
 138         }
 139
 140         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
 141         sgs[num_out + num_in++] = &status;
 142
 143         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 144 }
 145
 146 static void virtblk_add_req(struct virtblk_req *vbr, bool have_data)
 147 {
 148         struct virtio_blk *vblk = vbr->vblk;
 149         DEFINE_WAIT(wait);
 150         int ret;
 151
 152         spin_lock_irq(vblk->disk->queue->queue_lock);
 153         while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, vbr->sg,
 154                                                  have_data)) < 0)) {
 155                 prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
 156                                           TASK_UNINTERRUPTIBLE);
 157
 158                 spin_unlock_irq(vblk->disk->queue->queue_lock);
 159                 io_schedule();
 160                 spin_lock_irq(vblk->disk->queue->queue_lock);
 161
 162                 finish_wait(&vblk->queue_wait, &wait);
 163         }
 164
 165         virtqueue_kick(vblk->vq);
 166         spin_unlock_irq(vblk->disk->queue->queue_lock);
 167 }
 168
 169 static void virtblk_bio_send_flush(struct virtblk_req *vbr)
 170 {
 171         vbr->flags |= VBLK_IS_FLUSH;
 172         vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
 173         vbr->out_hdr.sector = 0;
 174         vbr->out_hdr.ioprio = 0;
 175
 176         virtblk_add_req(vbr, false);
 177 }
 178
 179 static void virtblk_bio_send_data(struct virtblk_req *vbr)
 180 {
 181         struct virtio_blk *vblk = vbr->vblk;
 182         struct bio *bio = vbr->bio;
 183         bool have_data;
 184
 185         vbr->flags &= ~VBLK_IS_FLUSH;
 186         vbr->out_hdr.type = 0;
 187         vbr->out_hdr.sector = bio->bi_sector;
 188         vbr->out_hdr.ioprio = bio_prio(bio);
 189
 190         if (blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg)) {
 191                 have_data = true;
 192                 if (bio->bi_rw & REQ_WRITE)
 193                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
 194                 else
 195                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
 196         } else
 197                 have_data = false;
 198
 199         virtblk_add_req(vbr, have_data);
 200 }
 201
 202 static void virtblk_bio_send_data_work(struct work_struct *work)
 203 {
 204         struct virtblk_req *vbr;
 205
 206         vbr = container_of(work, struct virtblk_req, work);
 207
 208         virtblk_bio_send_data(vbr);
 209 }
 210
 211 static void virtblk_bio_send_flush_work(struct work_struct *work)
 212 {
 213         struct virtblk_req *vbr;
 214
 215         vbr = container_of(work, struct virtblk_req, work);
 216
 217         virtblk_bio_send_flush(vbr);
 218 }
 219
 220 static inline void virtblk_request_done(struct virtblk_req *vbr)
 221 {
 222         struct virtio_blk *vblk = vbr->vblk;
 223         struct request *req = vbr->req;
 224         int error = virtblk_result(vbr);
 225
 226         if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
 227                 req->resid_len = vbr->in_hdr.residual;
 228                 req->sense_len = vbr->in_hdr.sense_len;
 229                 req->errors = vbr->in_hdr.errors;
 230         } else if (req->cmd_type == REQ_TYPE_SPECIAL) {
 231                 req->errors = (error != 0);
 232         }
 233
 234         __blk_end_request_all(req, error);
 235         mempool_free(vbr, vblk->pool);
 236 }
 237
 238 static inline void virtblk_bio_flush_done(struct virtblk_req *vbr)
 239 {
 240         struct virtio_blk *vblk = vbr->vblk;
 241
 242         if (vbr->flags & VBLK_REQ_DATA) {
 243                 /* Send out the actual write data */
 244                 INIT_WORK(&vbr->work, virtblk_bio_send_data_work);
 245                 queue_work(virtblk_wq, &vbr->work);
 246         } else {
 247                 bio_endio(vbr->bio, virtblk_result(vbr));
 248                 mempool_free(vbr, vblk->pool);
 249         }
 250 }
 251
 252 static inline void virtblk_bio_data_done(struct virtblk_req *vbr)
 253 {
 254         struct virtio_blk *vblk = vbr->vblk;
 255
 256         if (unlikely(vbr->flags & VBLK_REQ_FUA)) {
 257                 /* Send out a flush before end the bio */
 258                 vbr->flags &= ~VBLK_REQ_DATA;
 259                 INIT_WORK(&vbr->work, virtblk_bio_send_flush_work);
 260                 queue_work(virtblk_wq, &vbr->work);
 261         } else {
 262                 bio_endio(vbr->bio, virtblk_result(vbr));
 263                 mempool_free(vbr, vblk->pool);
 264         }
 265 }
 266
 267 static inline void virtblk_bio_done(struct virtblk_req *vbr)
 268 {
 269         if (unlikely(vbr->flags & VBLK_IS_FLUSH))
 270                 virtblk_bio_flush_done(vbr);
 271         else
 272                 virtblk_bio_data_done(vbr);
 273 }
 274
 275 static void virtblk_done(struct virtqueue *vq)
 276 {
 277         struct virtio_blk *vblk = vq->vdev->priv;
 278         bool bio_done = false, req_done = false;
 279         struct virtblk_req *vbr;
 280         unsigned long flags;
 281         unsigned int len;
 282
 283         spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
 284         do {
 285                 virtqueue_disable_cb(vq);
 286                 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
 287                         if (vbr->bio) {
 288                                 virtblk_bio_done(vbr);
 289                                 bio_done = true;
 290                         } else {
 291                                 virtblk_request_done(vbr);
 292                                 req_done = true;
 293                         }
 294                 }
 295         } while (!virtqueue_enable_cb(vq));
 296         /* In case queue is stopped waiting for more buffers. */
 297         if (req_done)
 298                 blk_start_queue(vblk->disk->queue);
 299         spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
 300
 301         if (bio_done)
 302                 wake_up(&vblk->queue_wait);
 303 }
 304
 305 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
 306                    struct request *req)
 307 {
 308         unsigned int num;
 309         struct virtblk_req *vbr;
 310
 311         vbr = virtblk_alloc_req(vblk, GFP_ATOMIC);
 312         if (!vbr)
 313                 /* When another request finishes we'll try again. */
 314                 return false;
 315
 316         vbr->req = req;
 317         vbr->bio = NULL;
 318         if (req->cmd_flags & REQ_FLUSH) {
 319                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
 320                 vbr->out_hdr.sector = 0;
 321                 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 322         } else {
 323                 switch (req->cmd_type) {
 324                 case REQ_TYPE_FS:
 325                         vbr->out_hdr.type = 0;
 326                         vbr->out_hdr.sector = blk_rq_pos(vbr->req);
 327                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 328                         break;
 329                 case REQ_TYPE_BLOCK_PC:
 330                         vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
 331                         vbr->out_hdr.sector = 0;
 332                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 333                         break;
 334                 case REQ_TYPE_SPECIAL:
 335                         vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
 336                         vbr->out_hdr.sector = 0;
 337                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
 338                         break;
 339                 default:
 340                         /* We don't put anything else in the queue. */
 341                         BUG();
 342                 }
 343         }
 344
 345         num = blk_rq_map_sg(q, vbr->req, vblk->sg);
 346         if (num) {
 347                 if (rq_data_dir(vbr->req) == WRITE)
 348                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
 349                 else
 350                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
 351         }
 352
 353         if (__virtblk_add_req(vblk->vq, vbr, vblk->sg, num) < 0) {
 354                 mempool_free(vbr, vblk->pool);
 355                 return false;
 356         }
 357
 358         return true;
 359 }
 360
 361 static void virtblk_request(struct request_queue *q)
 362 {
 363         struct virtio_blk *vblk = q->queuedata;
 364         struct request *req;
 365         unsigned int issued = 0;
 366
 367         while ((req = blk_peek_request(q)) != NULL) {
 368                 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
 369
 370                 /* If this request fails, stop queue and wait for something to
 371                    finish to restart it. */
 372                 if (!do_req(q, vblk, req)) {
 373                         blk_stop_queue(q);
 374                         break;
 375                 }
 376                 blk_start_request(req);
 377                 issued++;
 378         }
 379
 380         if (issued)
 381                 virtqueue_kick(vblk->vq);
 382 }
 383
 384 static void virtblk_make_request(struct request_queue *q, struct bio *bio)
 385 {
 386         struct virtio_blk *vblk = q->queuedata;
 387         struct virtblk_req *vbr;
 388
 389         BUG_ON(bio->bi_phys_segments + 2 > vblk->sg_elems);
 390
 391         vbr = virtblk_alloc_req(vblk, GFP_NOIO);
 392         if (!vbr) {
 393                 bio_endio(bio, -ENOMEM);
 394                 return;
 395         }
 396
 397         vbr->bio = bio;
 398         vbr->flags = 0;
 399         if (bio->bi_rw & REQ_FLUSH)
 400                 vbr->flags |= VBLK_REQ_FLUSH;
 401         if (bio->bi_rw & REQ_FUA)
 402                 vbr->flags |= VBLK_REQ_FUA;
 403         if (bio->bi_size)
 404                 vbr->flags |= VBLK_REQ_DATA;
 405
 406         if (unlikely(vbr->flags & VBLK_REQ_FLUSH))
 407                 virtblk_bio_send_flush(vbr);
 408         else
 409                 virtblk_bio_send_data(vbr);
 410 }
 411
 412 /* return id (s/n) string for *disk to *id_str
 413  */
 414 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 415 {
 416         struct virtio_blk *vblk = disk->private_data;
 417         struct request *req;
 418         struct bio *bio;
 419         int err;
 420
 421         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
 422                            GFP_KERNEL);
 423         if (IS_ERR(bio))
 424                 return PTR_ERR(bio);
 425
 426         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
 427         if (IS_ERR(req)) {
 428                 bio_put(bio);
 429                 return PTR_ERR(req);
 430         }
 431
 432         req->cmd_type = REQ_TYPE_SPECIAL;
 433         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
 434         blk_put_request(req);
 435
 436         return err;
 437 }
 438
 439 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 440                              unsigned int cmd, unsigned long data)
 441 {
 442         struct gendisk *disk = bdev->bd_disk;
 443         struct virtio_blk *vblk = disk->private_data;
 444
 445         /*
 446          * Only allow the generic SCSI ioctls if the host can support it.
 447          */
 448         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
 449                 return -ENOTTY;
 450
 451         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
 452                                   (void __user *)data);
 453 }
 454
 455 /* We provide getgeo only to please some old bootloader/partitioning tools */
 456 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 457 {
 458         struct virtio_blk *vblk = bd->bd_disk->private_data;
 459         struct virtio_blk_geometry vgeo;
 460         int err;
 461
 462         /* see if the host passed in geometry config */
 463         err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
 464                                 offsetof(struct virtio_blk_config, geometry),
 465                                 &vgeo);
 466
 467         if (!err) {
 468                 geo->heads = vgeo.heads;
 469                 geo->sectors = vgeo.sectors;
 470                 geo->cylinders = vgeo.cylinders;
 471         } else {
 472                 /* some standard values, similar to sd */
 473                 geo->heads = 1 << 6;
 474                 geo->sectors = 1 << 5;
 475                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 476         }
 477         return 0;
 478 }
 479
 480 static const struct block_device_operations virtblk_fops = {
 481         .ioctl  = virtblk_ioctl,
 482         .owner  = THIS_MODULE,
 483         .getgeo = virtblk_getgeo,
 484 };
 485
 486 static int index_to_minor(int index)
 487 {
 488         return index << PART_BITS;
 489 }
 490
 491 static int minor_to_index(int minor)
 492 {
 493         return minor >> PART_BITS;
 494 }
 495
 496 static ssize_t virtblk_serial_show(struct device *dev,
 497                                 struct device_attribute *attr, char *buf)
 498 {
 499         struct gendisk *disk = dev_to_disk(dev);
 500         int err;
 501
 502         /* sysfs gives us a PAGE_SIZE buffer */
 503         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 504
 505         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 506         err = virtblk_get_id(disk, buf);
 507         if (!err)
 508                 return strlen(buf);
 509
 510         if (err == -EIO) /* Unsupported? Make it empty. */
 511                 return 0;
 512
 513         return err;
 514 }
 515 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
 516
 517 static void virtblk_config_changed_work(struct work_struct *work)
 518 {
 519         struct virtio_blk *vblk =
 520                 container_of(work, struct virtio_blk, config_work);
 521         struct virtio_device *vdev = vblk->vdev;
 522         struct request_queue *q = vblk->disk->queue;
 523         char cap_str_2[10], cap_str_10[10];
 524         char *envp[] = { "RESIZE=1", NULL };
 525         u64 capacity, size;
 526
 527         mutex_lock(&vblk->config_lock);
 528         if (!vblk->config_enable)
 529                 goto done;
 530
 531         /* Host must always specify the capacity. */
 532         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 533                           &capacity, sizeof(capacity));
 534
 535         /* If capacity is too big, truncate with warning. */
 536         if ((sector_t)capacity != capacity) {
 537                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 538                          (unsigned long long)capacity);
 539                 capacity = (sector_t)-1;
 540         }
 541
 542         size = capacity * queue_logical_block_size(q);
 543         string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 544         string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 545
 546         dev_notice(&vdev->dev,
 547                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
 548                   (unsigned long long)capacity,
 549                   queue_logical_block_size(q),
 550                   cap_str_10, cap_str_2);
 551
 552         set_capacity(vblk->disk, capacity);
 553         revalidate_disk(vblk->disk);
 554         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
 555 done:
 556         mutex_unlock(&vblk->config_lock);
 557 }
 558
 559 static void virtblk_config_changed(struct virtio_device *vdev)
 560 {
 561         struct virtio_blk *vblk = vdev->priv;
 562
 563         queue_work(virtblk_wq, &vblk->config_work);
 564 }
 565
 566 static int init_vq(struct virtio_blk *vblk)
 567 {
 568         int err = 0;
 569
 570         /* We expect one virtqueue, for output. */
 571         vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests");
 572         if (IS_ERR(vblk->vq))
 573                 err = PTR_ERR(vblk->vq);
 574
 575         return err;
 576 }
 577
 578 /*
 579  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 580  * virtio blk but don't ever use it for any new driver.
 581  */
 582 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 583 {
 584         const int base = 'z' - 'a' + 1;
 585         char *begin = buf + strlen(prefix);
 586         char *end = buf + buflen;
 587         char *p;
 588         int unit;
 589
 590         p = end - 1;
 591         *p = '\0';
 592         unit = base;
 593         do {
 594                 if (p == begin)
 595                         return -EINVAL;
 596                 *--p = 'a' + (index % unit);
 597                 index = (index / unit) - 1;
 598         } while (index >= 0);
 599
 600         memmove(begin, p, end - p);
 601         memcpy(buf, prefix, strlen(prefix));
 602
 603         return 0;
 604 }
 605
 606 static int virtblk_get_cache_mode(struct virtio_device *vdev)
 607 {
 608         u8 writeback;
 609         int err;
 610
 611         err = virtio_config_val(vdev, VIRTIO_BLK_F_CONFIG_WCE,
 612                                 offsetof(struct virtio_blk_config, wce),
 613                                 &writeback);
 614         if (err)
 615                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
 616
 617         return writeback;
 618 }
 619
 620 static void virtblk_update_cache_mode(struct virtio_device *vdev)
 621 {
 622         u8 writeback = virtblk_get_cache_mode(vdev);
 623         struct virtio_blk *vblk = vdev->priv;
 624
 625         if (writeback)
 626                 blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
 627         else
 628                 blk_queue_flush(vblk->disk->queue, 0);
 629
 630         revalidate_disk(vblk->disk);
 631 }
 632
 633 static const char *const virtblk_cache_types[] = {
 634         "write through", "write back"
 635 };
 636
 637 static ssize_t
 638 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
 639                          const char *buf, size_t count)
 640 {
 641         struct gendisk *disk = dev_to_disk(dev);
 642         struct virtio_blk *vblk = disk->private_data;
 643         struct virtio_device *vdev = vblk->vdev;
 644         int i;
 645         u8 writeback;
 646
 647         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
 648         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
 649                 if (sysfs_streq(buf, virtblk_cache_types[i]))
 650                         break;
 651
 652         if (i < 0)
 653                 return -EINVAL;
 654
 655         writeback = i;
 656         vdev->config->set(vdev,
 657                           offsetof(struct virtio_blk_config, wce),
 658                           &writeback, sizeof(writeback));
 659
 660         virtblk_update_cache_mode(vdev);
 661         return count;
 662 }
 663
 664 static ssize_t
 665 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
 666                          char *buf)
 667 {
 668         struct gendisk *disk = dev_to_disk(dev);
 669         struct virtio_blk *vblk = disk->private_data;
 670         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
 671
 672         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
 673         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
 674 }
 675
 676 static const struct device_attribute dev_attr_cache_type_ro =
 677         __ATTR(cache_type, S_IRUGO,
 678                virtblk_cache_type_show, NULL);
 679 static const struct device_attribute dev_attr_cache_type_rw =
 680         __ATTR(cache_type, S_IRUGO|S_IWUSR,
 681                virtblk_cache_type_show, virtblk_cache_type_store);
 682
 683 static int virtblk_probe(struct virtio_device *vdev)
 684 {
 685         struct virtio_blk *vblk;
 686         struct request_queue *q;
 687         int err, index;
 688         int pool_size;
 689
 690         u64 cap;
 691         u32 v, blk_size, sg_elems, opt_io_size;
 692         u16 min_io_size;
 693         u8 physical_block_exp, alignment_offset;
 694
 695         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 696                              GFP_KERNEL);
 697         if (err < 0)
 698                 goto out;
 699         index = err;
 700
 701         /* We need to know how many segments before we allocate. */
 702         err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
 703                                 offsetof(struct virtio_blk_config, seg_max),
 704                                 &sg_elems);
 705
 706         /* We need at least one SG element, whatever they say. */
 707         if (err || !sg_elems)
 708                 sg_elems = 1;
 709
 710         /* We need an extra sg elements at head and tail. */
 711         sg_elems += 2;
 712         vdev->priv = vblk = kmalloc(sizeof(*vblk) +
 713                                     sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
 714         if (!vblk) {
 715                 err = -ENOMEM;
 716                 goto out_free_index;
 717         }
 718
 719         init_waitqueue_head(&vblk->queue_wait);
 720         vblk->vdev = vdev;
 721         vblk->sg_elems = sg_elems;
 722         sg_init_table(vblk->sg, vblk->sg_elems);
 723         mutex_init(&vblk->config_lock);
 724
 725         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 726         vblk->config_enable = true;
 727
 728         err = init_vq(vblk);
 729         if (err)
 730                 goto out_free_vblk;
 731
 732         pool_size = sizeof(struct virtblk_req);
 733         if (use_bio)
 734                 pool_size += sizeof(struct scatterlist) * sg_elems;
 735         vblk->pool = mempool_create_kmalloc_pool(1, pool_size);
 736         if (!vblk->pool) {
 737                 err = -ENOMEM;
 738                 goto out_free_vq;
 739         }
 740
 741         /* FIXME: How many partitions?  How long is a piece of string? */
 742         vblk->disk = alloc_disk(1 << PART_BITS);
 743         if (!vblk->disk) {
 744                 err = -ENOMEM;
 745                 goto out_mempool;
 746         }
 747
 748         q = vblk->disk->queue = blk_init_queue(virtblk_request, NULL);
 749         if (!q) {
 750                 err = -ENOMEM;
 751                 goto out_put_disk;
 752         }
 753
 754         if (use_bio)
 755                 blk_queue_make_request(q, virtblk_make_request);
 756         q->queuedata = vblk;
 757
 758         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 759
 760         vblk->disk->major = major;
 761         vblk->disk->first_minor = index_to_minor(index);
 762         vblk->disk->private_data = vblk;
 763         vblk->disk->fops = &virtblk_fops;
 764         vblk->disk->driverfs_dev = &vdev->dev;
 765         vblk->index = index;
 766
 767         /* configure queue flush support */
 768         virtblk_update_cache_mode(vdev);
 769
 770         /* If disk is read-only in the host, the guest should obey */
 771         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 772                 set_disk_ro(vblk->disk, 1);
 773
 774         /* Host must always specify the capacity. */
 775         vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
 776                           &cap, sizeof(cap));
 777
 778         /* If capacity is too big, truncate with warning. */
 779         if ((sector_t)cap != cap) {
 780                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 781                          (unsigned long long)cap);
 782                 cap = (sector_t)-1;
 783         }
 784         set_capacity(vblk->disk, cap);
 785
 786         /* We can handle whatever the host told us to handle. */
 787         blk_queue_max_segments(q, vblk->sg_elems-2);
 788
 789         /* No need to bounce any requests */
 790         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
 791
 792         /* No real sector limit. */
 793         blk_queue_max_hw_sectors(q, -1U);
 794
 795         /* Host can optionally specify maximum segment size and number of
 796          * segments. */
 797         err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
 798                                 offsetof(struct virtio_blk_config, size_max),
 799                                 &v);
 800         if (!err)
 801                 blk_queue_max_segment_size(q, v);
 802         else
 803                 blk_queue_max_segment_size(q, -1U);
 804
 805         /* Host can optionally specify the block size of the device */
 806         err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
 807                                 offsetof(struct virtio_blk_config, blk_size),
 808                                 &blk_size);
 809         if (!err)
 810                 blk_queue_logical_block_size(q, blk_size);
 811         else
 812                 blk_size = queue_logical_block_size(q);
 813
 814         /* Use topology information if available */
 815         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 816                         offsetof(struct virtio_blk_config, physical_block_exp),
 817                         &physical_block_exp);
 818         if (!err && physical_block_exp)
 819                 blk_queue_physical_block_size(q,
 820                                 blk_size * (1 << physical_block_exp));
 821
 822         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 823                         offsetof(struct virtio_blk_config, alignment_offset),
 824                         &alignment_offset);
 825         if (!err && alignment_offset)
 826                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
 827
 828         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 829                         offsetof(struct virtio_blk_config, min_io_size),
 830                         &min_io_size);
 831         if (!err && min_io_size)
 832                 blk_queue_io_min(q, blk_size * min_io_size);
 833
 834         err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
 835                         offsetof(struct virtio_blk_config, opt_io_size),
 836                         &opt_io_size);
 837         if (!err && opt_io_size)
 838                 blk_queue_io_opt(q, blk_size * opt_io_size);
 839
 840         add_disk(vblk->disk);
 841         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
 842         if (err)
 843                 goto out_del_disk;
 844
 845         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
 846                 err = device_create_file(disk_to_dev(vblk->disk),
 847                                          &dev_attr_cache_type_rw);
 848         else
 849                 err = device_create_file(disk_to_dev(vblk->disk),
 850                                          &dev_attr_cache_type_ro);
 851         if (err)
 852                 goto out_del_disk;
 853         return 0;
 854
 855 out_del_disk:
 856         del_gendisk(vblk->disk);
 857         blk_cleanup_queue(vblk->disk->queue);
 858 out_put_disk:
 859         put_disk(vblk->disk);
 860 out_mempool:
 861         mempool_destroy(vblk->pool);
 862 out_free_vq:
 863         vdev->config->del_vqs(vdev);
 864 out_free_vblk:
 865         kfree(vblk);
 866 out_free_index:
 867         ida_simple_remove(&vd_index_ida, index);
 868 out:
 869         return err;
 870 }
 871
 872 static void virtblk_remove(struct virtio_device *vdev)
 873 {
 874         struct virtio_blk *vblk = vdev->priv;
 875         int index = vblk->index;
 876         int refc;
 877
 878         /* Prevent config work handler from accessing the device. */
 879         mutex_lock(&vblk->config_lock);
 880         vblk->config_enable = false;
 881         mutex_unlock(&vblk->config_lock);
 882
 883         del_gendisk(vblk->disk);
 884         blk_cleanup_queue(vblk->disk->queue);
 885
 886         /* Stop all the virtqueues. */
 887         vdev->config->reset(vdev);
 888
 889         flush_work(&vblk->config_work);
 890
 891         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
 892         put_disk(vblk->disk);
 893         mempool_destroy(vblk->pool);
 894         vdev->config->del_vqs(vdev);
 895         kfree(vblk);
 896
 897         /* Only free device id if we don't have any users */
 898         if (refc == 1)
 899                 ida_simple_remove(&vd_index_ida, index);
 900 }
 901
 902 #ifdef CONFIG_PM
 903 static int virtblk_freeze(struct virtio_device *vdev)
 904 {
 905         struct virtio_blk *vblk = vdev->priv;
 906
 907         /* Ensure we don't receive any more interrupts */
 908         vdev->config->reset(vdev);
 909
 910         /* Prevent config work handler from accessing the device. */
 911         mutex_lock(&vblk->config_lock);
 912         vblk->config_enable = false;
 913         mutex_unlock(&vblk->config_lock);
 914
 915         flush_work(&vblk->config_work);
 916
 917         spin_lock_irq(vblk->disk->queue->queue_lock);
 918         blk_stop_queue(vblk->disk->queue);
 919         spin_unlock_irq(vblk->disk->queue->queue_lock);
 920         blk_sync_queue(vblk->disk->queue);
 921
 922         vdev->config->del_vqs(vdev);
 923         return 0;
 924 }
 925
 926 static int virtblk_restore(struct virtio_device *vdev)
 927 {
 928         struct virtio_blk *vblk = vdev->priv;
 929         int ret;
 930
 931         vblk->config_enable = true;
 932         ret = init_vq(vdev->priv);
 933         if (!ret) {
 934                 spin_lock_irq(vblk->disk->queue->queue_lock);
 935                 blk_start_queue(vblk->disk->queue);
 936                 spin_unlock_irq(vblk->disk->queue->queue_lock);
 937         }
 938         return ret;
 939 }
 940 #endif
 941
 942 static const struct virtio_device_id id_table[] = {
 943         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 944         { 0 },
 945 };
 946
 947 static unsigned int features[] = {
 948         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
 949         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
 950         VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE
 951 };
 952
 953 static struct virtio_driver virtio_blk = {
 954         .feature_table          = features,
 955         .feature_table_size     = ARRAY_SIZE(features),
 956         .driver.name            = KBUILD_MODNAME,
 957         .driver.owner           = THIS_MODULE,
 958         .id_table               = id_table,
 959         .probe                  = virtblk_probe,
 960         .remove                 = virtblk_remove,
 961         .config_changed         = virtblk_config_changed,
 962 #ifdef CONFIG_PM
 963         .freeze                 = virtblk_freeze,
 964         .restore                = virtblk_restore,
 965 #endif
 966 };
 967
 968 static int __init init(void)
 969 {
 970         int error;
 971
 972         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
 973         if (!virtblk_wq)
 974                 return -ENOMEM;
 975
 976         major = register_blkdev(0, "virtblk");
 977         if (major < 0) {
 978                 error = major;
 979                 goto out_destroy_workqueue;
 980         }
 981
 982         error = register_virtio_driver(&virtio_blk);
 983         if (error)
 984                 goto out_unregister_blkdev;
 985         return 0;
 986
 987 out_unregister_blkdev:
 988         unregister_blkdev(major, "virtblk");
 989 out_destroy_workqueue:
 990         destroy_workqueue(virtblk_wq);
 991         return error;
 992 }
 993
 994 static void __exit fini(void)
 995 {
 996         unregister_blkdev(major, "virtblk");
 997         unregister_virtio_driver(&virtio_blk);
 998         destroy_workqueue(virtblk_wq);
 999 }
1000 module_init(init);
1001 module_exit(fini);
1002
1003 MODULE_DEVICE_TABLE(virtio, id_table);
1004 MODULE_DESCRIPTION("Virtio block driver");
1005 MODULE_LICENSE("GPL");