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 #include <linux/idr.h> 13 14 #define PART_BITS 4 15 16 static int major; 17 static DEFINE_IDA(vd_index_ida); 18 19 struct workqueue_struct *virtblk_wq; 20 21 struct virtio_blk 22 { 23 spinlock_t lock; 24 25 struct virtio_device *vdev; 26 struct virtqueue *vq; 27 28 /* The disk structure for the kernel. */ 29 struct gendisk *disk; 30 31 /* Request tracking. */ 32 struct list_head reqs; 33 34 mempool_t *pool; 35 36 /* Process context for config space updates */ 37 struct work_struct config_work; 38 39 /* What host tells us, plus 2 for header & tailer. */ 40 unsigned int sg_elems; 41 42 /* Ida index - used to track minor number allocations. */ 43 int index; 44 45 /* Scatterlist: can be too big for stack. */ 46 struct scatterlist sg[/*sg_elems*/]; 47 }; 48 49 struct virtblk_req 50 { 51 struct list_head list; 52 struct request *req; 53 struct virtio_blk_outhdr out_hdr; 54 struct virtio_scsi_inhdr in_hdr; 55 u8 status; 56 }; 57 58 static void blk_done(struct virtqueue *vq) 59 { 60 struct virtio_blk *vblk = vq->vdev->priv; 61 struct virtblk_req *vbr; 62 unsigned int len; 63 unsigned long flags; 64 65 spin_lock_irqsave(&vblk->lock, flags); 66 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { 67 int error; 68 69 switch (vbr->status) { 70 case VIRTIO_BLK_S_OK: 71 error = 0; 72 break; 73 case VIRTIO_BLK_S_UNSUPP: 74 error = -ENOTTY; 75 break; 76 default: 77 error = -EIO; 78 break; 79 } 80 81 switch (vbr->req->cmd_type) { 82 case REQ_TYPE_BLOCK_PC: 83 vbr->req->resid_len = vbr->in_hdr.residual; 84 vbr->req->sense_len = vbr->in_hdr.sense_len; 85 vbr->req->errors = vbr->in_hdr.errors; 86 break; 87 case REQ_TYPE_SPECIAL: 88 vbr->req->errors = (error != 0); 89 break; 90 default: 91 break; 92 } 93 94 __blk_end_request_all(vbr->req, error); 95 list_del(&vbr->list); 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->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) < 0) { 176 mempool_free(vbr, vblk->pool); 177 return false; 178 } 179 180 list_add_tail(&vbr->list, &vblk->reqs); 181 return true; 182 } 183 184 static void do_virtblk_request(struct request_queue *q) 185 { 186 struct virtio_blk *vblk = q->queuedata; 187 struct request *req; 188 unsigned int issued = 0; 189 190 while ((req = blk_peek_request(q)) != NULL) { 191 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 192 193 /* If this request fails, stop queue and wait for something to 194 finish to restart it. */ 195 if (!do_req(q, vblk, req)) { 196 blk_stop_queue(q); 197 break; 198 } 199 blk_start_request(req); 200 issued++; 201 } 202 203 if (issued) 204 virtqueue_kick(vblk->vq); 205 } 206 207 /* return id (s/n) string for *disk to *id_str 208 */ 209 static int virtblk_get_id(struct gendisk *disk, char *id_str) 210 { 211 struct virtio_blk *vblk = disk->private_data; 212 struct request *req; 213 struct bio *bio; 214 int err; 215 216 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, 217 GFP_KERNEL); 218 if (IS_ERR(bio)) 219 return PTR_ERR(bio); 220 221 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); 222 if (IS_ERR(req)) { 223 bio_put(bio); 224 return PTR_ERR(req); 225 } 226 227 req->cmd_type = REQ_TYPE_SPECIAL; 228 err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); 229 blk_put_request(req); 230 231 return err; 232 } 233 234 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 235 unsigned int cmd, unsigned long data) 236 { 237 struct gendisk *disk = bdev->bd_disk; 238 struct virtio_blk *vblk = disk->private_data; 239 240 /* 241 * Only allow the generic SCSI ioctls if the host can support it. 242 */ 243 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 244 return -ENOTTY; 245 246 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 247 (void __user *)data); 248 } 249 250 /* We provide getgeo only to please some old bootloader/partitioning tools */ 251 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 252 { 253 struct virtio_blk *vblk = bd->bd_disk->private_data; 254 struct virtio_blk_geometry vgeo; 255 int err; 256 257 /* see if the host passed in geometry config */ 258 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 259 offsetof(struct virtio_blk_config, geometry), 260 &vgeo); 261 262 if (!err) { 263 geo->heads = vgeo.heads; 264 geo->sectors = vgeo.sectors; 265 geo->cylinders = vgeo.cylinders; 266 } else { 267 /* some standard values, similar to sd */ 268 geo->heads = 1 << 6; 269 geo->sectors = 1 << 5; 270 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 271 } 272 return 0; 273 } 274 275 static const struct block_device_operations virtblk_fops = { 276 .ioctl = virtblk_ioctl, 277 .owner = THIS_MODULE, 278 .getgeo = virtblk_getgeo, 279 }; 280 281 static int index_to_minor(int index) 282 { 283 return index << PART_BITS; 284 } 285 286 static int minor_to_index(int minor) 287 { 288 return minor >> PART_BITS; 289 } 290 291 static ssize_t virtblk_serial_show(struct device *dev, 292 struct device_attribute *attr, char *buf) 293 { 294 struct gendisk *disk = dev_to_disk(dev); 295 int err; 296 297 /* sysfs gives us a PAGE_SIZE buffer */ 298 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 299 300 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 301 err = virtblk_get_id(disk, buf); 302 if (!err) 303 return strlen(buf); 304 305 if (err == -EIO) /* Unsupported? Make it empty. */ 306 return 0; 307 308 return err; 309 } 310 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 311 312 static void virtblk_config_changed_work(struct work_struct *work) 313 { 314 struct virtio_blk *vblk = 315 container_of(work, struct virtio_blk, config_work); 316 struct virtio_device *vdev = vblk->vdev; 317 struct request_queue *q = vblk->disk->queue; 318 char cap_str_2[10], cap_str_10[10]; 319 u64 capacity, size; 320 321 /* Host must always specify the capacity. */ 322 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 323 &capacity, sizeof(capacity)); 324 325 /* If capacity is too big, truncate with warning. */ 326 if ((sector_t)capacity != capacity) { 327 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 328 (unsigned long long)capacity); 329 capacity = (sector_t)-1; 330 } 331 332 size = capacity * queue_logical_block_size(q); 333 string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2)); 334 string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10)); 335 336 dev_notice(&vdev->dev, 337 "new size: %llu %d-byte logical blocks (%s/%s)\n", 338 (unsigned long long)capacity, 339 queue_logical_block_size(q), 340 cap_str_10, cap_str_2); 341 342 set_capacity(vblk->disk, capacity); 343 } 344 345 static void virtblk_config_changed(struct virtio_device *vdev) 346 { 347 struct virtio_blk *vblk = vdev->priv; 348 349 queue_work(virtblk_wq, &vblk->config_work); 350 } 351 352 static int __devinit virtblk_probe(struct virtio_device *vdev) 353 { 354 struct virtio_blk *vblk; 355 struct request_queue *q; 356 int err, index; 357 u64 cap; 358 u32 v, blk_size, sg_elems, opt_io_size; 359 u16 min_io_size; 360 u8 physical_block_exp, alignment_offset; 361 362 err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS), 363 GFP_KERNEL); 364 if (err < 0) 365 goto out; 366 index = err; 367 368 /* We need to know how many segments before we allocate. */ 369 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 370 offsetof(struct virtio_blk_config, seg_max), 371 &sg_elems); 372 373 /* We need at least one SG element, whatever they say. */ 374 if (err || !sg_elems) 375 sg_elems = 1; 376 377 /* We need an extra sg elements at head and tail. */ 378 sg_elems += 2; 379 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 380 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 381 if (!vblk) { 382 err = -ENOMEM; 383 goto out_free_index; 384 } 385 386 INIT_LIST_HEAD(&vblk->reqs); 387 spin_lock_init(&vblk->lock); 388 vblk->vdev = vdev; 389 vblk->sg_elems = sg_elems; 390 sg_init_table(vblk->sg, vblk->sg_elems); 391 INIT_WORK(&vblk->config_work, virtblk_config_changed_work); 392 393 /* We expect one virtqueue, for output. */ 394 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 395 if (IS_ERR(vblk->vq)) { 396 err = PTR_ERR(vblk->vq); 397 goto out_free_vblk; 398 } 399 400 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 401 if (!vblk->pool) { 402 err = -ENOMEM; 403 goto out_free_vq; 404 } 405 406 /* FIXME: How many partitions? How long is a piece of string? */ 407 vblk->disk = alloc_disk(1 << PART_BITS); 408 if (!vblk->disk) { 409 err = -ENOMEM; 410 goto out_mempool; 411 } 412 413 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 414 if (!q) { 415 err = -ENOMEM; 416 goto out_put_disk; 417 } 418 419 q->queuedata = vblk; 420 421 if (index < 26) { 422 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 423 } else if (index < (26 + 1) * 26) { 424 sprintf(vblk->disk->disk_name, "vd%c%c", 425 'a' + index / 26 - 1, 'a' + index % 26); 426 } else { 427 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 428 const unsigned int m2 = (index / 26 - 1) % 26; 429 const unsigned int m3 = index % 26; 430 sprintf(vblk->disk->disk_name, "vd%c%c%c", 431 'a' + m1, 'a' + m2, 'a' + m3); 432 } 433 434 vblk->disk->major = major; 435 vblk->disk->first_minor = index_to_minor(index); 436 vblk->disk->private_data = vblk; 437 vblk->disk->fops = &virtblk_fops; 438 vblk->disk->driverfs_dev = &vdev->dev; 439 vblk->index = index; 440 441 /* configure queue flush support */ 442 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) 443 blk_queue_flush(q, REQ_FLUSH); 444 445 /* If disk is read-only in the host, the guest should obey */ 446 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 447 set_disk_ro(vblk->disk, 1); 448 449 /* Host must always specify the capacity. */ 450 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 451 &cap, sizeof(cap)); 452 453 /* If capacity is too big, truncate with warning. */ 454 if ((sector_t)cap != cap) { 455 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 456 (unsigned long long)cap); 457 cap = (sector_t)-1; 458 } 459 set_capacity(vblk->disk, cap); 460 461 /* We can handle whatever the host told us to handle. */ 462 blk_queue_max_segments(q, vblk->sg_elems-2); 463 464 /* No need to bounce any requests */ 465 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); 466 467 /* No real sector limit. */ 468 blk_queue_max_hw_sectors(q, -1U); 469 470 /* Host can optionally specify maximum segment size and number of 471 * segments. */ 472 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 473 offsetof(struct virtio_blk_config, size_max), 474 &v); 475 if (!err) 476 blk_queue_max_segment_size(q, v); 477 else 478 blk_queue_max_segment_size(q, -1U); 479 480 /* Host can optionally specify the block size of the device */ 481 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 482 offsetof(struct virtio_blk_config, blk_size), 483 &blk_size); 484 if (!err) 485 blk_queue_logical_block_size(q, blk_size); 486 else 487 blk_size = queue_logical_block_size(q); 488 489 /* Use topology information if available */ 490 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 491 offsetof(struct virtio_blk_config, physical_block_exp), 492 &physical_block_exp); 493 if (!err && physical_block_exp) 494 blk_queue_physical_block_size(q, 495 blk_size * (1 << physical_block_exp)); 496 497 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 498 offsetof(struct virtio_blk_config, alignment_offset), 499 &alignment_offset); 500 if (!err && alignment_offset) 501 blk_queue_alignment_offset(q, blk_size * alignment_offset); 502 503 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 504 offsetof(struct virtio_blk_config, min_io_size), 505 &min_io_size); 506 if (!err && min_io_size) 507 blk_queue_io_min(q, blk_size * min_io_size); 508 509 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 510 offsetof(struct virtio_blk_config, opt_io_size), 511 &opt_io_size); 512 if (!err && opt_io_size) 513 blk_queue_io_opt(q, blk_size * opt_io_size); 514 515 516 add_disk(vblk->disk); 517 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); 518 if (err) 519 goto out_del_disk; 520 521 return 0; 522 523 out_del_disk: 524 del_gendisk(vblk->disk); 525 blk_cleanup_queue(vblk->disk->queue); 526 out_put_disk: 527 put_disk(vblk->disk); 528 out_mempool: 529 mempool_destroy(vblk->pool); 530 out_free_vq: 531 vdev->config->del_vqs(vdev); 532 out_free_vblk: 533 kfree(vblk); 534 out_free_index: 535 ida_simple_remove(&vd_index_ida, index); 536 out: 537 return err; 538 } 539 540 static void __devexit virtblk_remove(struct virtio_device *vdev) 541 { 542 struct virtio_blk *vblk = vdev->priv; 543 int index = vblk->index; 544 545 flush_work(&vblk->config_work); 546 547 /* Nothing should be pending. */ 548 BUG_ON(!list_empty(&vblk->reqs)); 549 550 /* Stop all the virtqueues. */ 551 vdev->config->reset(vdev); 552 553 del_gendisk(vblk->disk); 554 blk_cleanup_queue(vblk->disk->queue); 555 put_disk(vblk->disk); 556 mempool_destroy(vblk->pool); 557 vdev->config->del_vqs(vdev); 558 kfree(vblk); 559 ida_simple_remove(&vd_index_ida, index); 560 } 561 562 static const struct virtio_device_id id_table[] = { 563 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 564 { 0 }, 565 }; 566 567 static unsigned int features[] = { 568 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, 569 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, 570 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY 571 }; 572 573 /* 574 * virtio_blk causes spurious section mismatch warning by 575 * simultaneously referring to a __devinit and a __devexit function. 576 * Use __refdata to avoid this warning. 577 */ 578 static struct virtio_driver __refdata virtio_blk = { 579 .feature_table = features, 580 .feature_table_size = ARRAY_SIZE(features), 581 .driver.name = KBUILD_MODNAME, 582 .driver.owner = THIS_MODULE, 583 .id_table = id_table, 584 .probe = virtblk_probe, 585 .remove = __devexit_p(virtblk_remove), 586 .config_changed = virtblk_config_changed, 587 }; 588 589 static int __init init(void) 590 { 591 int error; 592 593 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0); 594 if (!virtblk_wq) 595 return -ENOMEM; 596 597 major = register_blkdev(0, "virtblk"); 598 if (major < 0) { 599 error = major; 600 goto out_destroy_workqueue; 601 } 602 603 error = register_virtio_driver(&virtio_blk); 604 if (error) 605 goto out_unregister_blkdev; 606 return 0; 607 608 out_unregister_blkdev: 609 unregister_blkdev(major, "virtblk"); 610 out_destroy_workqueue: 611 destroy_workqueue(virtblk_wq); 612 return error; 613 } 614 615 static void __exit fini(void) 616 { 617 unregister_blkdev(major, "virtblk"); 618 unregister_virtio_driver(&virtio_blk); 619 destroy_workqueue(virtblk_wq); 620 } 621 module_init(init); 622 module_exit(fini); 623 624 MODULE_DEVICE_TABLE(virtio, id_table); 625 MODULE_DESCRIPTION("Virtio block driver"); 626 MODULE_LICENSE("GPL"); 627