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; 205 206 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, 207 GFP_KERNEL); 208 if (IS_ERR(bio)) 209 return PTR_ERR(bio); 210 211 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); 212 if (IS_ERR(req)) { 213 bio_put(bio); 214 return PTR_ERR(req); 215 } 216 217 req->cmd_type = REQ_TYPE_SPECIAL; 218 return blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); 219 } 220 221 static int virtblk_locked_ioctl(struct block_device *bdev, fmode_t mode, 222 unsigned cmd, unsigned long data) 223 { 224 struct gendisk *disk = bdev->bd_disk; 225 struct virtio_blk *vblk = disk->private_data; 226 227 /* 228 * Only allow the generic SCSI ioctls if the host can support it. 229 */ 230 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 231 return -ENOTTY; 232 233 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 234 (void __user *)data); 235 } 236 237 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 238 unsigned int cmd, unsigned long param) 239 { 240 int ret; 241 242 lock_kernel(); 243 ret = virtblk_locked_ioctl(bdev, mode, cmd, param); 244 unlock_kernel(); 245 246 return ret; 247 } 248 249 /* We provide getgeo only to please some old bootloader/partitioning tools */ 250 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 251 { 252 struct virtio_blk *vblk = bd->bd_disk->private_data; 253 struct virtio_blk_geometry vgeo; 254 int err; 255 256 /* see if the host passed in geometry config */ 257 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 258 offsetof(struct virtio_blk_config, geometry), 259 &vgeo); 260 261 if (!err) { 262 geo->heads = vgeo.heads; 263 geo->sectors = vgeo.sectors; 264 geo->cylinders = vgeo.cylinders; 265 } else { 266 /* some standard values, similar to sd */ 267 geo->heads = 1 << 6; 268 geo->sectors = 1 << 5; 269 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 270 } 271 return 0; 272 } 273 274 static const struct block_device_operations virtblk_fops = { 275 .ioctl = virtblk_ioctl, 276 .owner = THIS_MODULE, 277 .getgeo = virtblk_getgeo, 278 }; 279 280 static int index_to_minor(int index) 281 { 282 return index << PART_BITS; 283 } 284 285 static ssize_t virtblk_serial_show(struct device *dev, 286 struct device_attribute *attr, char *buf) 287 { 288 struct gendisk *disk = dev_to_disk(dev); 289 int err; 290 291 /* sysfs gives us a PAGE_SIZE buffer */ 292 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 293 294 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 295 err = virtblk_get_id(disk, buf); 296 if (!err) 297 return strlen(buf); 298 299 if (err == -EIO) /* Unsupported? Make it empty. */ 300 return 0; 301 302 return err; 303 } 304 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 305 306 static int __devinit virtblk_probe(struct virtio_device *vdev) 307 { 308 struct virtio_blk *vblk; 309 struct request_queue *q; 310 int err; 311 u64 cap; 312 u32 v, blk_size, sg_elems, opt_io_size; 313 u16 min_io_size; 314 u8 physical_block_exp, alignment_offset; 315 316 if (index_to_minor(index) >= 1 << MINORBITS) 317 return -ENOSPC; 318 319 /* We need to know how many segments before we allocate. */ 320 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 321 offsetof(struct virtio_blk_config, seg_max), 322 &sg_elems); 323 324 /* We need at least one SG element, whatever they say. */ 325 if (err || !sg_elems) 326 sg_elems = 1; 327 328 /* We need an extra sg elements at head and tail. */ 329 sg_elems += 2; 330 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 331 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 332 if (!vblk) { 333 err = -ENOMEM; 334 goto out; 335 } 336 337 INIT_LIST_HEAD(&vblk->reqs); 338 spin_lock_init(&vblk->lock); 339 vblk->vdev = vdev; 340 vblk->sg_elems = sg_elems; 341 sg_init_table(vblk->sg, vblk->sg_elems); 342 343 /* We expect one virtqueue, for output. */ 344 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 345 if (IS_ERR(vblk->vq)) { 346 err = PTR_ERR(vblk->vq); 347 goto out_free_vblk; 348 } 349 350 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 351 if (!vblk->pool) { 352 err = -ENOMEM; 353 goto out_free_vq; 354 } 355 356 /* FIXME: How many partitions? How long is a piece of string? */ 357 vblk->disk = alloc_disk(1 << PART_BITS); 358 if (!vblk->disk) { 359 err = -ENOMEM; 360 goto out_mempool; 361 } 362 363 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 364 if (!q) { 365 err = -ENOMEM; 366 goto out_put_disk; 367 } 368 369 q->queuedata = vblk; 370 371 if (index < 26) { 372 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 373 } else if (index < (26 + 1) * 26) { 374 sprintf(vblk->disk->disk_name, "vd%c%c", 375 'a' + index / 26 - 1, 'a' + index % 26); 376 } else { 377 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 378 const unsigned int m2 = (index / 26 - 1) % 26; 379 const unsigned int m3 = index % 26; 380 sprintf(vblk->disk->disk_name, "vd%c%c%c", 381 'a' + m1, 'a' + m2, 'a' + m3); 382 } 383 384 vblk->disk->major = major; 385 vblk->disk->first_minor = index_to_minor(index); 386 vblk->disk->private_data = vblk; 387 vblk->disk->fops = &virtblk_fops; 388 vblk->disk->driverfs_dev = &vdev->dev; 389 index++; 390 391 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) { 392 /* 393 * If the FLUSH feature is supported we do have support for 394 * flushing a volatile write cache on the host. Use that 395 * to implement write barrier support. 396 */ 397 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH); 398 } else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) { 399 /* 400 * If the BARRIER feature is supported the host expects us 401 * to order request by tags. This implies there is not 402 * volatile write cache on the host, and that the host 403 * never re-orders outstanding I/O. This feature is not 404 * useful for real life scenarious and deprecated. 405 */ 406 blk_queue_ordered(q, QUEUE_ORDERED_TAG); 407 } else { 408 /* 409 * If the FLUSH feature is not supported we must assume that 410 * the host does not perform any kind of volatile write 411 * caching. We still need to drain the queue to provider 412 * proper barrier semantics. 413 */ 414 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN); 415 } 416 417 /* If disk is read-only in the host, the guest should obey */ 418 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 419 set_disk_ro(vblk->disk, 1); 420 421 /* Host must always specify the capacity. */ 422 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 423 &cap, sizeof(cap)); 424 425 /* If capacity is too big, truncate with warning. */ 426 if ((sector_t)cap != cap) { 427 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 428 (unsigned long long)cap); 429 cap = (sector_t)-1; 430 } 431 set_capacity(vblk->disk, cap); 432 433 /* We can handle whatever the host told us to handle. */ 434 blk_queue_max_segments(q, vblk->sg_elems-2); 435 436 /* No need to bounce any requests */ 437 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); 438 439 /* No real sector limit. */ 440 blk_queue_max_hw_sectors(q, -1U); 441 442 /* Host can optionally specify maximum segment size and number of 443 * segments. */ 444 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 445 offsetof(struct virtio_blk_config, size_max), 446 &v); 447 if (!err) 448 blk_queue_max_segment_size(q, v); 449 else 450 blk_queue_max_segment_size(q, -1U); 451 452 /* Host can optionally specify the block size of the device */ 453 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 454 offsetof(struct virtio_blk_config, blk_size), 455 &blk_size); 456 if (!err) 457 blk_queue_logical_block_size(q, blk_size); 458 else 459 blk_size = queue_logical_block_size(q); 460 461 /* Use topology information if available */ 462 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 463 offsetof(struct virtio_blk_config, physical_block_exp), 464 &physical_block_exp); 465 if (!err && physical_block_exp) 466 blk_queue_physical_block_size(q, 467 blk_size * (1 << physical_block_exp)); 468 469 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 470 offsetof(struct virtio_blk_config, alignment_offset), 471 &alignment_offset); 472 if (!err && alignment_offset) 473 blk_queue_alignment_offset(q, blk_size * alignment_offset); 474 475 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 476 offsetof(struct virtio_blk_config, min_io_size), 477 &min_io_size); 478 if (!err && min_io_size) 479 blk_queue_io_min(q, blk_size * min_io_size); 480 481 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 482 offsetof(struct virtio_blk_config, opt_io_size), 483 &opt_io_size); 484 if (!err && opt_io_size) 485 blk_queue_io_opt(q, blk_size * opt_io_size); 486 487 488 add_disk(vblk->disk); 489 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); 490 if (err) 491 goto out_del_disk; 492 493 return 0; 494 495 out_del_disk: 496 del_gendisk(vblk->disk); 497 blk_cleanup_queue(vblk->disk->queue); 498 out_put_disk: 499 put_disk(vblk->disk); 500 out_mempool: 501 mempool_destroy(vblk->pool); 502 out_free_vq: 503 vdev->config->del_vqs(vdev); 504 out_free_vblk: 505 kfree(vblk); 506 out: 507 return err; 508 } 509 510 static void __devexit virtblk_remove(struct virtio_device *vdev) 511 { 512 struct virtio_blk *vblk = vdev->priv; 513 514 /* Nothing should be pending. */ 515 BUG_ON(!list_empty(&vblk->reqs)); 516 517 /* Stop all the virtqueues. */ 518 vdev->config->reset(vdev); 519 520 del_gendisk(vblk->disk); 521 blk_cleanup_queue(vblk->disk->queue); 522 put_disk(vblk->disk); 523 mempool_destroy(vblk->pool); 524 vdev->config->del_vqs(vdev); 525 kfree(vblk); 526 } 527 528 static const struct virtio_device_id id_table[] = { 529 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 530 { 0 }, 531 }; 532 533 static unsigned int features[] = { 534 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 535 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 536 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY 537 }; 538 539 /* 540 * virtio_blk causes spurious section mismatch warning by 541 * simultaneously referring to a __devinit and a __devexit function. 542 * Use __refdata to avoid this warning. 543 */ 544 static struct virtio_driver __refdata virtio_blk = { 545 .feature_table = features, 546 .feature_table_size = ARRAY_SIZE(features), 547 .driver.name = KBUILD_MODNAME, 548 .driver.owner = THIS_MODULE, 549 .id_table = id_table, 550 .probe = virtblk_probe, 551 .remove = __devexit_p(virtblk_remove), 552 }; 553 554 static int __init init(void) 555 { 556 major = register_blkdev(0, "virtblk"); 557 if (major < 0) 558 return major; 559 return register_virtio_driver(&virtio_blk); 560 } 561 562 static void __exit fini(void) 563 { 564 unregister_blkdev(major, "virtblk"); 565 unregister_virtio_driver(&virtio_blk); 566 } 567 module_init(init); 568 module_exit(fini); 569 570 MODULE_DEVICE_TABLE(virtio, id_table); 571 MODULE_DESCRIPTION("Virtio block driver"); 572 MODULE_LICENSE("GPL"); 573