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