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/virtio.h> 8 #include <linux/virtio_blk.h> 9 #include <linux/scatterlist.h> 10 #include <linux/string_helpers.h> 11 #include <scsi/scsi_cmnd.h> 12 13 #define PART_BITS 4 14 15 static int major, index; 16 struct workqueue_struct *virtblk_wq; 17 18 struct virtio_blk 19 { 20 spinlock_t lock; 21 22 struct virtio_device *vdev; 23 struct virtqueue *vq; 24 25 /* The disk structure for the kernel. */ 26 struct gendisk *disk; 27 28 /* Request tracking. */ 29 struct list_head reqs; 30 31 mempool_t *pool; 32 33 /* Process context for config space updates */ 34 struct work_struct config_work; 35 36 /* What host tells us, plus 2 for header & tailer. */ 37 unsigned int sg_elems; 38 39 /* Scatterlist: can be too big for stack. */ 40 struct scatterlist sg[/*sg_elems*/]; 41 }; 42 43 struct virtblk_req 44 { 45 struct list_head list; 46 struct request *req; 47 struct virtio_blk_outhdr out_hdr; 48 struct virtio_scsi_inhdr in_hdr; 49 u8 status; 50 }; 51 52 static void blk_done(struct virtqueue *vq) 53 { 54 struct virtio_blk *vblk = vq->vdev->priv; 55 struct virtblk_req *vbr; 56 unsigned int len; 57 unsigned long flags; 58 59 spin_lock_irqsave(&vblk->lock, flags); 60 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { 61 int error; 62 63 switch (vbr->status) { 64 case VIRTIO_BLK_S_OK: 65 error = 0; 66 break; 67 case VIRTIO_BLK_S_UNSUPP: 68 error = -ENOTTY; 69 break; 70 default: 71 error = -EIO; 72 break; 73 } 74 75 switch (vbr->req->cmd_type) { 76 case REQ_TYPE_BLOCK_PC: 77 vbr->req->resid_len = vbr->in_hdr.residual; 78 vbr->req->sense_len = vbr->in_hdr.sense_len; 79 vbr->req->errors = vbr->in_hdr.errors; 80 break; 81 case REQ_TYPE_SPECIAL: 82 vbr->req->errors = (error != 0); 83 break; 84 default: 85 break; 86 } 87 88 __blk_end_request_all(vbr->req, error); 89 list_del(&vbr->list); 90 mempool_free(vbr, vblk->pool); 91 } 92 /* In case queue is stopped waiting for more buffers. */ 93 blk_start_queue(vblk->disk->queue); 94 spin_unlock_irqrestore(&vblk->lock, flags); 95 } 96 97 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 98 struct request *req) 99 { 100 unsigned long num, out = 0, in = 0; 101 struct virtblk_req *vbr; 102 103 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 104 if (!vbr) 105 /* When another request finishes we'll try again. */ 106 return false; 107 108 vbr->req = req; 109 110 if (req->cmd_flags & REQ_FLUSH) { 111 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; 112 vbr->out_hdr.sector = 0; 113 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 114 } else { 115 switch (req->cmd_type) { 116 case REQ_TYPE_FS: 117 vbr->out_hdr.type = 0; 118 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 119 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 120 break; 121 case REQ_TYPE_BLOCK_PC: 122 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 123 vbr->out_hdr.sector = 0; 124 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 125 break; 126 case REQ_TYPE_SPECIAL: 127 vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID; 128 vbr->out_hdr.sector = 0; 129 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 130 break; 131 default: 132 /* We don't put anything else in the queue. */ 133 BUG(); 134 } 135 } 136 137 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 138 139 /* 140 * If this is a packet command we need a couple of additional headers. 141 * Behind the normal outhdr we put a segment with the scsi command 142 * block, and before the normal inhdr we put the sense data and the 143 * inhdr with additional status information before the normal inhdr. 144 */ 145 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) 146 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 147 148 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 149 150 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) { 151 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE); 152 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 153 sizeof(vbr->in_hdr)); 154 } 155 156 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 157 sizeof(vbr->status)); 158 159 if (num) { 160 if (rq_data_dir(vbr->req) == WRITE) { 161 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 162 out += num; 163 } else { 164 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 165 in += num; 166 } 167 } 168 169 if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 170 mempool_free(vbr, vblk->pool); 171 return false; 172 } 173 174 list_add_tail(&vbr->list, &vblk->reqs); 175 return true; 176 } 177 178 static void do_virtblk_request(struct request_queue *q) 179 { 180 struct virtio_blk *vblk = q->queuedata; 181 struct request *req; 182 unsigned int issued = 0; 183 184 while ((req = blk_peek_request(q)) != NULL) { 185 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 186 187 /* If this request fails, stop queue and wait for something to 188 finish to restart it. */ 189 if (!do_req(q, vblk, req)) { 190 blk_stop_queue(q); 191 break; 192 } 193 blk_start_request(req); 194 issued++; 195 } 196 197 if (issued) 198 virtqueue_kick(vblk->vq); 199 } 200 201 /* return id (s/n) string for *disk to *id_str 202 */ 203 static int virtblk_get_id(struct gendisk *disk, char *id_str) 204 { 205 struct virtio_blk *vblk = disk->private_data; 206 struct request *req; 207 struct bio *bio; 208 int err; 209 210 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, 211 GFP_KERNEL); 212 if (IS_ERR(bio)) 213 return PTR_ERR(bio); 214 215 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); 216 if (IS_ERR(req)) { 217 bio_put(bio); 218 return PTR_ERR(req); 219 } 220 221 req->cmd_type = REQ_TYPE_SPECIAL; 222 err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); 223 blk_put_request(req); 224 225 return err; 226 } 227 228 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 229 unsigned int cmd, unsigned long data) 230 { 231 struct gendisk *disk = bdev->bd_disk; 232 struct virtio_blk *vblk = disk->private_data; 233 234 /* 235 * Only allow the generic SCSI ioctls if the host can support it. 236 */ 237 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 238 return -ENOTTY; 239 240 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 241 (void __user *)data); 242 } 243 244 /* We provide getgeo only to please some old bootloader/partitioning tools */ 245 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 246 { 247 struct virtio_blk *vblk = bd->bd_disk->private_data; 248 struct virtio_blk_geometry vgeo; 249 int err; 250 251 /* see if the host passed in geometry config */ 252 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 253 offsetof(struct virtio_blk_config, geometry), 254 &vgeo); 255 256 if (!err) { 257 geo->heads = vgeo.heads; 258 geo->sectors = vgeo.sectors; 259 geo->cylinders = vgeo.cylinders; 260 } else { 261 /* some standard values, similar to sd */ 262 geo->heads = 1 << 6; 263 geo->sectors = 1 << 5; 264 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 265 } 266 return 0; 267 } 268 269 static const struct block_device_operations virtblk_fops = { 270 .ioctl = virtblk_ioctl, 271 .owner = THIS_MODULE, 272 .getgeo = virtblk_getgeo, 273 }; 274 275 static int index_to_minor(int index) 276 { 277 return index << PART_BITS; 278 } 279 280 static ssize_t virtblk_serial_show(struct device *dev, 281 struct device_attribute *attr, char *buf) 282 { 283 struct gendisk *disk = dev_to_disk(dev); 284 int err; 285 286 /* sysfs gives us a PAGE_SIZE buffer */ 287 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 288 289 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 290 err = virtblk_get_id(disk, buf); 291 if (!err) 292 return strlen(buf); 293 294 if (err == -EIO) /* Unsupported? Make it empty. */ 295 return 0; 296 297 return err; 298 } 299 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 300 301 static void virtblk_config_changed_work(struct work_struct *work) 302 { 303 struct virtio_blk *vblk = 304 container_of(work, struct virtio_blk, config_work); 305 struct virtio_device *vdev = vblk->vdev; 306 struct request_queue *q = vblk->disk->queue; 307 char cap_str_2[10], cap_str_10[10]; 308 u64 capacity, size; 309 310 /* Host must always specify the capacity. */ 311 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 312 &capacity, sizeof(capacity)); 313 314 /* If capacity is too big, truncate with warning. */ 315 if ((sector_t)capacity != capacity) { 316 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 317 (unsigned long long)capacity); 318 capacity = (sector_t)-1; 319 } 320 321 size = capacity * queue_logical_block_size(q); 322 string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2)); 323 string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10)); 324 325 dev_notice(&vdev->dev, 326 "new size: %llu %d-byte logical blocks (%s/%s)\n", 327 (unsigned long long)capacity, 328 queue_logical_block_size(q), 329 cap_str_10, cap_str_2); 330 331 set_capacity(vblk->disk, capacity); 332 } 333 334 static void virtblk_config_changed(struct virtio_device *vdev) 335 { 336 struct virtio_blk *vblk = vdev->priv; 337 338 queue_work(virtblk_wq, &vblk->config_work); 339 } 340 341 static int __devinit virtblk_probe(struct virtio_device *vdev) 342 { 343 struct virtio_blk *vblk; 344 struct request_queue *q; 345 int err; 346 u64 cap; 347 u32 v, blk_size, sg_elems, opt_io_size; 348 u16 min_io_size; 349 u8 physical_block_exp, alignment_offset; 350 351 if (index_to_minor(index) >= 1 << MINORBITS) 352 return -ENOSPC; 353 354 /* We need to know how many segments before we allocate. */ 355 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 356 offsetof(struct virtio_blk_config, seg_max), 357 &sg_elems); 358 359 /* We need at least one SG element, whatever they say. */ 360 if (err || !sg_elems) 361 sg_elems = 1; 362 363 /* We need an extra sg elements at head and tail. */ 364 sg_elems += 2; 365 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 366 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 367 if (!vblk) { 368 err = -ENOMEM; 369 goto out; 370 } 371 372 INIT_LIST_HEAD(&vblk->reqs); 373 spin_lock_init(&vblk->lock); 374 vblk->vdev = vdev; 375 vblk->sg_elems = sg_elems; 376 sg_init_table(vblk->sg, vblk->sg_elems); 377 INIT_WORK(&vblk->config_work, virtblk_config_changed_work); 378 379 /* We expect one virtqueue, for output. */ 380 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 381 if (IS_ERR(vblk->vq)) { 382 err = PTR_ERR(vblk->vq); 383 goto out_free_vblk; 384 } 385 386 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 387 if (!vblk->pool) { 388 err = -ENOMEM; 389 goto out_free_vq; 390 } 391 392 /* FIXME: How many partitions? How long is a piece of string? */ 393 vblk->disk = alloc_disk(1 << PART_BITS); 394 if (!vblk->disk) { 395 err = -ENOMEM; 396 goto out_mempool; 397 } 398 399 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 400 if (!q) { 401 err = -ENOMEM; 402 goto out_put_disk; 403 } 404 405 q->queuedata = vblk; 406 407 if (index < 26) { 408 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 409 } else if (index < (26 + 1) * 26) { 410 sprintf(vblk->disk->disk_name, "vd%c%c", 411 'a' + index / 26 - 1, 'a' + index % 26); 412 } else { 413 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 414 const unsigned int m2 = (index / 26 - 1) % 26; 415 const unsigned int m3 = index % 26; 416 sprintf(vblk->disk->disk_name, "vd%c%c%c", 417 'a' + m1, 'a' + m2, 'a' + m3); 418 } 419 420 vblk->disk->major = major; 421 vblk->disk->first_minor = index_to_minor(index); 422 vblk->disk->private_data = vblk; 423 vblk->disk->fops = &virtblk_fops; 424 vblk->disk->driverfs_dev = &vdev->dev; 425 index++; 426 427 /* configure queue flush support */ 428 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) 429 blk_queue_flush(q, REQ_FLUSH); 430 431 /* If disk is read-only in the host, the guest should obey */ 432 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 433 set_disk_ro(vblk->disk, 1); 434 435 /* Host must always specify the capacity. */ 436 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 437 &cap, sizeof(cap)); 438 439 /* If capacity is too big, truncate with warning. */ 440 if ((sector_t)cap != cap) { 441 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 442 (unsigned long long)cap); 443 cap = (sector_t)-1; 444 } 445 set_capacity(vblk->disk, cap); 446 447 /* We can handle whatever the host told us to handle. */ 448 blk_queue_max_segments(q, vblk->sg_elems-2); 449 450 /* No need to bounce any requests */ 451 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); 452 453 /* No real sector limit. */ 454 blk_queue_max_hw_sectors(q, -1U); 455 456 /* Host can optionally specify maximum segment size and number of 457 * segments. */ 458 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 459 offsetof(struct virtio_blk_config, size_max), 460 &v); 461 if (!err) 462 blk_queue_max_segment_size(q, v); 463 else 464 blk_queue_max_segment_size(q, -1U); 465 466 /* Host can optionally specify the block size of the device */ 467 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 468 offsetof(struct virtio_blk_config, blk_size), 469 &blk_size); 470 if (!err) 471 blk_queue_logical_block_size(q, blk_size); 472 else 473 blk_size = queue_logical_block_size(q); 474 475 /* Use topology information if available */ 476 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 477 offsetof(struct virtio_blk_config, physical_block_exp), 478 &physical_block_exp); 479 if (!err && physical_block_exp) 480 blk_queue_physical_block_size(q, 481 blk_size * (1 << physical_block_exp)); 482 483 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 484 offsetof(struct virtio_blk_config, alignment_offset), 485 &alignment_offset); 486 if (!err && alignment_offset) 487 blk_queue_alignment_offset(q, blk_size * alignment_offset); 488 489 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 490 offsetof(struct virtio_blk_config, min_io_size), 491 &min_io_size); 492 if (!err && min_io_size) 493 blk_queue_io_min(q, blk_size * min_io_size); 494 495 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 496 offsetof(struct virtio_blk_config, opt_io_size), 497 &opt_io_size); 498 if (!err && opt_io_size) 499 blk_queue_io_opt(q, blk_size * opt_io_size); 500 501 502 add_disk(vblk->disk); 503 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); 504 if (err) 505 goto out_del_disk; 506 507 return 0; 508 509 out_del_disk: 510 del_gendisk(vblk->disk); 511 blk_cleanup_queue(vblk->disk->queue); 512 out_put_disk: 513 put_disk(vblk->disk); 514 out_mempool: 515 mempool_destroy(vblk->pool); 516 out_free_vq: 517 vdev->config->del_vqs(vdev); 518 out_free_vblk: 519 kfree(vblk); 520 out: 521 return err; 522 } 523 524 static void __devexit virtblk_remove(struct virtio_device *vdev) 525 { 526 struct virtio_blk *vblk = vdev->priv; 527 528 flush_work(&vblk->config_work); 529 530 /* Nothing should be pending. */ 531 BUG_ON(!list_empty(&vblk->reqs)); 532 533 /* Stop all the virtqueues. */ 534 vdev->config->reset(vdev); 535 536 del_gendisk(vblk->disk); 537 blk_cleanup_queue(vblk->disk->queue); 538 put_disk(vblk->disk); 539 mempool_destroy(vblk->pool); 540 vdev->config->del_vqs(vdev); 541 kfree(vblk); 542 } 543 544 static const struct virtio_device_id id_table[] = { 545 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 546 { 0 }, 547 }; 548 549 static unsigned int features[] = { 550 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, 551 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, 552 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY 553 }; 554 555 /* 556 * virtio_blk causes spurious section mismatch warning by 557 * simultaneously referring to a __devinit and a __devexit function. 558 * Use __refdata to avoid this warning. 559 */ 560 static struct virtio_driver __refdata virtio_blk = { 561 .feature_table = features, 562 .feature_table_size = ARRAY_SIZE(features), 563 .driver.name = KBUILD_MODNAME, 564 .driver.owner = THIS_MODULE, 565 .id_table = id_table, 566 .probe = virtblk_probe, 567 .remove = __devexit_p(virtblk_remove), 568 .config_changed = virtblk_config_changed, 569 }; 570 571 static int __init init(void) 572 { 573 int error; 574 575 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0); 576 if (!virtblk_wq) 577 return -ENOMEM; 578 579 major = register_blkdev(0, "virtblk"); 580 if (major < 0) { 581 error = major; 582 goto out_destroy_workqueue; 583 } 584 585 error = register_virtio_driver(&virtio_blk); 586 if (error) 587 goto out_unregister_blkdev; 588 return 0; 589 590 out_unregister_blkdev: 591 unregister_blkdev(major, "virtblk"); 592 out_destroy_workqueue: 593 destroy_workqueue(virtblk_wq); 594 return error; 595 } 596 597 static void __exit fini(void) 598 { 599 unregister_blkdev(major, "virtblk"); 600 unregister_virtio_driver(&virtio_blk); 601 destroy_workqueue(virtblk_wq); 602 } 603 module_init(init); 604 module_exit(fini); 605 606 MODULE_DEVICE_TABLE(virtio, id_table); 607 MODULE_DESCRIPTION("Virtio block driver"); 608 MODULE_LICENSE("GPL"); 609