1 //#define DEBUG 2 #include <linux/spinlock.h> 3 #include <linux/slab.h> 4 #include <linux/blkdev.h> 5 #include <linux/smp_lock.h> 6 #include <linux/hdreg.h> 7 #include <linux/virtio.h> 8 #include <linux/virtio_blk.h> 9 #include <linux/scatterlist.h> 10 11 #define PART_BITS 4 12 13 static int major, index; 14 15 struct virtio_blk 16 { 17 spinlock_t lock; 18 19 struct virtio_device *vdev; 20 struct virtqueue *vq; 21 22 /* The disk structure for the kernel. */ 23 struct gendisk *disk; 24 25 /* Request tracking. */ 26 struct list_head reqs; 27 28 mempool_t *pool; 29 30 /* What host tells us, plus 2 for header & tailer. */ 31 unsigned int sg_elems; 32 33 /* Scatterlist: can be too big for stack. */ 34 struct scatterlist sg[/*sg_elems*/]; 35 }; 36 37 struct virtblk_req 38 { 39 struct list_head list; 40 struct request *req; 41 struct virtio_blk_outhdr out_hdr; 42 struct virtio_scsi_inhdr in_hdr; 43 u8 status; 44 }; 45 46 static void blk_done(struct virtqueue *vq) 47 { 48 struct virtio_blk *vblk = vq->vdev->priv; 49 struct virtblk_req *vbr; 50 unsigned int len; 51 unsigned long flags; 52 53 spin_lock_irqsave(&vblk->lock, flags); 54 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { 55 int error; 56 57 switch (vbr->status) { 58 case VIRTIO_BLK_S_OK: 59 error = 0; 60 break; 61 case VIRTIO_BLK_S_UNSUPP: 62 error = -ENOTTY; 63 break; 64 default: 65 error = -EIO; 66 break; 67 } 68 69 switch (vbr->req->cmd_type) { 70 case REQ_TYPE_BLOCK_PC: 71 vbr->req->resid_len = vbr->in_hdr.residual; 72 vbr->req->sense_len = vbr->in_hdr.sense_len; 73 vbr->req->errors = vbr->in_hdr.errors; 74 break; 75 case REQ_TYPE_SPECIAL: 76 vbr->req->errors = (error != 0); 77 break; 78 default: 79 break; 80 } 81 82 __blk_end_request_all(vbr->req, error); 83 list_del(&vbr->list); 84 mempool_free(vbr, vblk->pool); 85 } 86 /* In case queue is stopped waiting for more buffers. */ 87 blk_start_queue(vblk->disk->queue); 88 spin_unlock_irqrestore(&vblk->lock, flags); 89 } 90 91 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 92 struct request *req) 93 { 94 unsigned long num, out = 0, in = 0; 95 struct virtblk_req *vbr; 96 97 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 98 if (!vbr) 99 /* When another request finishes we'll try again. */ 100 return false; 101 102 vbr->req = req; 103 104 if (req->cmd_flags & REQ_FLUSH) { 105 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; 106 vbr->out_hdr.sector = 0; 107 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 108 } else { 109 switch (req->cmd_type) { 110 case REQ_TYPE_FS: 111 vbr->out_hdr.type = 0; 112 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 113 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 114 break; 115 case REQ_TYPE_BLOCK_PC: 116 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 117 vbr->out_hdr.sector = 0; 118 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 119 break; 120 case REQ_TYPE_SPECIAL: 121 vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID; 122 vbr->out_hdr.sector = 0; 123 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 124 break; 125 default: 126 /* We don't put anything else in the queue. */ 127 BUG(); 128 } 129 } 130 131 if (vbr->req->cmd_flags & REQ_HARDBARRIER) 132 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 133 134 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 135 136 /* 137 * If this is a packet command we need a couple of additional headers. 138 * Behind the normal outhdr we put a segment with the scsi command 139 * block, and before the normal inhdr we put the sense data and the 140 * inhdr with additional status information before the normal inhdr. 141 */ 142 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) 143 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 144 145 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 146 147 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) { 148 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96); 149 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 150 sizeof(vbr->in_hdr)); 151 } 152 153 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 154 sizeof(vbr->status)); 155 156 if (num) { 157 if (rq_data_dir(vbr->req) == WRITE) { 158 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 159 out += num; 160 } else { 161 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 162 in += num; 163 } 164 } 165 166 if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 167 mempool_free(vbr, vblk->pool); 168 return false; 169 } 170 171 list_add_tail(&vbr->list, &vblk->reqs); 172 return true; 173 } 174 175 static void do_virtblk_request(struct request_queue *q) 176 { 177 struct virtio_blk *vblk = q->queuedata; 178 struct request *req; 179 unsigned int issued = 0; 180 181 while ((req = blk_peek_request(q)) != NULL) { 182 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 183 184 /* If this request fails, stop queue and wait for something to 185 finish to restart it. */ 186 if (!do_req(q, vblk, req)) { 187 blk_stop_queue(q); 188 break; 189 } 190 blk_start_request(req); 191 issued++; 192 } 193 194 if (issued) 195 virtqueue_kick(vblk->vq); 196 } 197 198 /* return id (s/n) string for *disk to *id_str 199 */ 200 static int virtblk_get_id(struct gendisk *disk, char *id_str) 201 { 202 struct virtio_blk *vblk = disk->private_data; 203 struct request *req; 204 struct bio *bio; 205 int err; 206 207 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, 208 GFP_KERNEL); 209 if (IS_ERR(bio)) 210 return PTR_ERR(bio); 211 212 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); 213 if (IS_ERR(req)) { 214 bio_put(bio); 215 return PTR_ERR(req); 216 } 217 218 req->cmd_type = REQ_TYPE_SPECIAL; 219 err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); 220 blk_put_request(req); 221 222 return err; 223 } 224 225 static int virtblk_locked_ioctl(struct block_device *bdev, fmode_t mode, 226 unsigned cmd, unsigned long data) 227 { 228 struct gendisk *disk = bdev->bd_disk; 229 struct virtio_blk *vblk = disk->private_data; 230 231 /* 232 * Only allow the generic SCSI ioctls if the host can support it. 233 */ 234 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 235 return -ENOTTY; 236 237 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 238 (void __user *)data); 239 } 240 241 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 242 unsigned int cmd, unsigned long param) 243 { 244 int ret; 245 246 lock_kernel(); 247 ret = virtblk_locked_ioctl(bdev, mode, cmd, param); 248 unlock_kernel(); 249 250 return ret; 251 } 252 253 /* We provide getgeo only to please some old bootloader/partitioning tools */ 254 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 255 { 256 struct virtio_blk *vblk = bd->bd_disk->private_data; 257 struct virtio_blk_geometry vgeo; 258 int err; 259 260 /* see if the host passed in geometry config */ 261 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 262 offsetof(struct virtio_blk_config, geometry), 263 &vgeo); 264 265 if (!err) { 266 geo->heads = vgeo.heads; 267 geo->sectors = vgeo.sectors; 268 geo->cylinders = vgeo.cylinders; 269 } else { 270 /* some standard values, similar to sd */ 271 geo->heads = 1 << 6; 272 geo->sectors = 1 << 5; 273 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 274 } 275 return 0; 276 } 277 278 static const struct block_device_operations virtblk_fops = { 279 .ioctl = virtblk_ioctl, 280 .owner = THIS_MODULE, 281 .getgeo = virtblk_getgeo, 282 }; 283 284 static int index_to_minor(int index) 285 { 286 return index << PART_BITS; 287 } 288 289 static ssize_t virtblk_serial_show(struct device *dev, 290 struct device_attribute *attr, char *buf) 291 { 292 struct gendisk *disk = dev_to_disk(dev); 293 int err; 294 295 /* sysfs gives us a PAGE_SIZE buffer */ 296 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 297 298 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 299 err = virtblk_get_id(disk, buf); 300 if (!err) 301 return strlen(buf); 302 303 if (err == -EIO) /* Unsupported? Make it empty. */ 304 return 0; 305 306 return err; 307 } 308 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 309 310 static int __devinit virtblk_probe(struct virtio_device *vdev) 311 { 312 struct virtio_blk *vblk; 313 struct request_queue *q; 314 int err; 315 u64 cap; 316 u32 v, blk_size, sg_elems, opt_io_size; 317 u16 min_io_size; 318 u8 physical_block_exp, alignment_offset; 319 320 if (index_to_minor(index) >= 1 << MINORBITS) 321 return -ENOSPC; 322 323 /* We need to know how many segments before we allocate. */ 324 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 325 offsetof(struct virtio_blk_config, seg_max), 326 &sg_elems); 327 328 /* We need at least one SG element, whatever they say. */ 329 if (err || !sg_elems) 330 sg_elems = 1; 331 332 /* We need an extra sg elements at head and tail. */ 333 sg_elems += 2; 334 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 335 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 336 if (!vblk) { 337 err = -ENOMEM; 338 goto out; 339 } 340 341 INIT_LIST_HEAD(&vblk->reqs); 342 spin_lock_init(&vblk->lock); 343 vblk->vdev = vdev; 344 vblk->sg_elems = sg_elems; 345 sg_init_table(vblk->sg, vblk->sg_elems); 346 347 /* We expect one virtqueue, for output. */ 348 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 349 if (IS_ERR(vblk->vq)) { 350 err = PTR_ERR(vblk->vq); 351 goto out_free_vblk; 352 } 353 354 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 355 if (!vblk->pool) { 356 err = -ENOMEM; 357 goto out_free_vq; 358 } 359 360 /* FIXME: How many partitions? How long is a piece of string? */ 361 vblk->disk = alloc_disk(1 << PART_BITS); 362 if (!vblk->disk) { 363 err = -ENOMEM; 364 goto out_mempool; 365 } 366 367 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 368 if (!q) { 369 err = -ENOMEM; 370 goto out_put_disk; 371 } 372 373 q->queuedata = vblk; 374 375 if (index < 26) { 376 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 377 } else if (index < (26 + 1) * 26) { 378 sprintf(vblk->disk->disk_name, "vd%c%c", 379 'a' + index / 26 - 1, 'a' + index % 26); 380 } else { 381 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 382 const unsigned int m2 = (index / 26 - 1) % 26; 383 const unsigned int m3 = index % 26; 384 sprintf(vblk->disk->disk_name, "vd%c%c%c", 385 'a' + m1, 'a' + m2, 'a' + m3); 386 } 387 388 vblk->disk->major = major; 389 vblk->disk->first_minor = index_to_minor(index); 390 vblk->disk->private_data = vblk; 391 vblk->disk->fops = &virtblk_fops; 392 vblk->disk->driverfs_dev = &vdev->dev; 393 index++; 394 395 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) { 396 /* 397 * If the FLUSH feature is supported we do have support for 398 * flushing a volatile write cache on the host. Use that 399 * to implement write barrier support. 400 */ 401 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH); 402 } else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) { 403 /* 404 * If the BARRIER feature is supported the host expects us 405 * to order request by tags. This implies there is not 406 * volatile write cache on the host, and that the host 407 * never re-orders outstanding I/O. This feature is not 408 * useful for real life scenarious and deprecated. 409 */ 410 blk_queue_ordered(q, QUEUE_ORDERED_TAG); 411 } else { 412 /* 413 * If the FLUSH feature is not supported we must assume that 414 * the host does not perform any kind of volatile write 415 * caching. We still need to drain the queue to provider 416 * proper barrier semantics. 417 */ 418 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN); 419 } 420 421 /* If disk is read-only in the host, the guest should obey */ 422 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 423 set_disk_ro(vblk->disk, 1); 424 425 /* Host must always specify the capacity. */ 426 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 427 &cap, sizeof(cap)); 428 429 /* If capacity is too big, truncate with warning. */ 430 if ((sector_t)cap != cap) { 431 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 432 (unsigned long long)cap); 433 cap = (sector_t)-1; 434 } 435 set_capacity(vblk->disk, cap); 436 437 /* We can handle whatever the host told us to handle. */ 438 blk_queue_max_segments(q, vblk->sg_elems-2); 439 440 /* No need to bounce any requests */ 441 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); 442 443 /* No real sector limit. */ 444 blk_queue_max_hw_sectors(q, -1U); 445 446 /* Host can optionally specify maximum segment size and number of 447 * segments. */ 448 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 449 offsetof(struct virtio_blk_config, size_max), 450 &v); 451 if (!err) 452 blk_queue_max_segment_size(q, v); 453 else 454 blk_queue_max_segment_size(q, -1U); 455 456 /* Host can optionally specify the block size of the device */ 457 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 458 offsetof(struct virtio_blk_config, blk_size), 459 &blk_size); 460 if (!err) 461 blk_queue_logical_block_size(q, blk_size); 462 else 463 blk_size = queue_logical_block_size(q); 464 465 /* Use topology information if available */ 466 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 467 offsetof(struct virtio_blk_config, physical_block_exp), 468 &physical_block_exp); 469 if (!err && physical_block_exp) 470 blk_queue_physical_block_size(q, 471 blk_size * (1 << physical_block_exp)); 472 473 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 474 offsetof(struct virtio_blk_config, alignment_offset), 475 &alignment_offset); 476 if (!err && alignment_offset) 477 blk_queue_alignment_offset(q, blk_size * alignment_offset); 478 479 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 480 offsetof(struct virtio_blk_config, min_io_size), 481 &min_io_size); 482 if (!err && min_io_size) 483 blk_queue_io_min(q, blk_size * min_io_size); 484 485 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 486 offsetof(struct virtio_blk_config, opt_io_size), 487 &opt_io_size); 488 if (!err && opt_io_size) 489 blk_queue_io_opt(q, blk_size * opt_io_size); 490 491 492 add_disk(vblk->disk); 493 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); 494 if (err) 495 goto out_del_disk; 496 497 return 0; 498 499 out_del_disk: 500 del_gendisk(vblk->disk); 501 blk_cleanup_queue(vblk->disk->queue); 502 out_put_disk: 503 put_disk(vblk->disk); 504 out_mempool: 505 mempool_destroy(vblk->pool); 506 out_free_vq: 507 vdev->config->del_vqs(vdev); 508 out_free_vblk: 509 kfree(vblk); 510 out: 511 return err; 512 } 513 514 static void __devexit virtblk_remove(struct virtio_device *vdev) 515 { 516 struct virtio_blk *vblk = vdev->priv; 517 518 /* Nothing should be pending. */ 519 BUG_ON(!list_empty(&vblk->reqs)); 520 521 /* Stop all the virtqueues. */ 522 vdev->config->reset(vdev); 523 524 del_gendisk(vblk->disk); 525 blk_cleanup_queue(vblk->disk->queue); 526 put_disk(vblk->disk); 527 mempool_destroy(vblk->pool); 528 vdev->config->del_vqs(vdev); 529 kfree(vblk); 530 } 531 532 static const struct virtio_device_id id_table[] = { 533 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 534 { 0 }, 535 }; 536 537 static unsigned int features[] = { 538 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 539 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 540 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY 541 }; 542 543 /* 544 * virtio_blk causes spurious section mismatch warning by 545 * simultaneously referring to a __devinit and a __devexit function. 546 * Use __refdata to avoid this warning. 547 */ 548 static struct virtio_driver __refdata virtio_blk = { 549 .feature_table = features, 550 .feature_table_size = ARRAY_SIZE(features), 551 .driver.name = KBUILD_MODNAME, 552 .driver.owner = THIS_MODULE, 553 .id_table = id_table, 554 .probe = virtblk_probe, 555 .remove = __devexit_p(virtblk_remove), 556 }; 557 558 static int __init init(void) 559 { 560 major = register_blkdev(0, "virtblk"); 561 if (major < 0) 562 return major; 563 return register_virtio_driver(&virtio_blk); 564 } 565 566 static void __exit fini(void) 567 { 568 unregister_blkdev(major, "virtblk"); 569 unregister_virtio_driver(&virtio_blk); 570 } 571 module_init(init); 572 module_exit(fini); 573 574 MODULE_DEVICE_TABLE(virtio, id_table); 575 MODULE_DESCRIPTION("Virtio block driver"); 576 MODULE_LICENSE("GPL"); 577