1 //#define DEBUG 2 #include <linux/spinlock.h> 3 #include <linux/blkdev.h> 4 #include <linux/hdreg.h> 5 #include <linux/virtio.h> 6 #include <linux/virtio_ids.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 = vblk->vq->vq_ops->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 if (blk_pc_request(vbr->req)) { 69 vbr->req->resid_len = vbr->in_hdr.residual; 70 vbr->req->sense_len = vbr->in_hdr.sense_len; 71 vbr->req->errors = vbr->in_hdr.errors; 72 } 73 74 __blk_end_request_all(vbr->req, error); 75 list_del(&vbr->list); 76 mempool_free(vbr, vblk->pool); 77 } 78 /* In case queue is stopped waiting for more buffers. */ 79 blk_start_queue(vblk->disk->queue); 80 spin_unlock_irqrestore(&vblk->lock, flags); 81 } 82 83 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 84 struct request *req) 85 { 86 unsigned long num, out = 0, in = 0; 87 struct virtblk_req *vbr; 88 89 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 90 if (!vbr) 91 /* When another request finishes we'll try again. */ 92 return false; 93 94 vbr->req = req; 95 switch (req->cmd_type) { 96 case REQ_TYPE_FS: 97 vbr->out_hdr.type = 0; 98 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 99 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 100 break; 101 case REQ_TYPE_BLOCK_PC: 102 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 103 vbr->out_hdr.sector = 0; 104 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 105 break; 106 case REQ_TYPE_LINUX_BLOCK: 107 if (req->cmd[0] == REQ_LB_OP_FLUSH) { 108 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; 109 vbr->out_hdr.sector = 0; 110 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 111 break; 112 } 113 /*FALLTHRU*/ 114 default: 115 /* We don't put anything else in the queue. */ 116 BUG(); 117 } 118 119 if (blk_barrier_rq(vbr->req)) 120 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 121 122 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 123 124 /* 125 * If this is a packet command we need a couple of additional headers. 126 * Behind the normal outhdr we put a segment with the scsi command 127 * block, and before the normal inhdr we put the sense data and the 128 * inhdr with additional status information before the normal inhdr. 129 */ 130 if (blk_pc_request(vbr->req)) 131 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 132 133 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 134 135 if (blk_pc_request(vbr->req)) { 136 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96); 137 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 138 sizeof(vbr->in_hdr)); 139 } 140 141 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 142 sizeof(vbr->status)); 143 144 if (num) { 145 if (rq_data_dir(vbr->req) == WRITE) { 146 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 147 out += num; 148 } else { 149 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 150 in += num; 151 } 152 } 153 154 if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 155 mempool_free(vbr, vblk->pool); 156 return false; 157 } 158 159 list_add_tail(&vbr->list, &vblk->reqs); 160 return true; 161 } 162 163 static void do_virtblk_request(struct request_queue *q) 164 { 165 struct virtio_blk *vblk = q->queuedata; 166 struct request *req; 167 unsigned int issued = 0; 168 169 while ((req = blk_peek_request(q)) != NULL) { 170 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 171 172 /* If this request fails, stop queue and wait for something to 173 finish to restart it. */ 174 if (!do_req(q, vblk, req)) { 175 blk_stop_queue(q); 176 break; 177 } 178 blk_start_request(req); 179 issued++; 180 } 181 182 if (issued) 183 vblk->vq->vq_ops->kick(vblk->vq); 184 } 185 186 /* return ATA identify data 187 */ 188 static int virtblk_identify(struct gendisk *disk, void *argp) 189 { 190 struct virtio_blk *vblk = disk->private_data; 191 void *opaque; 192 int err = -ENOMEM; 193 194 opaque = kmalloc(VIRTIO_BLK_ID_BYTES, GFP_KERNEL); 195 if (!opaque) 196 goto out; 197 198 err = virtio_config_buf(vblk->vdev, VIRTIO_BLK_F_IDENTIFY, 199 offsetof(struct virtio_blk_config, identify), opaque, 200 VIRTIO_BLK_ID_BYTES); 201 202 if (err) 203 goto out_kfree; 204 205 if (copy_to_user(argp, opaque, VIRTIO_BLK_ID_BYTES)) 206 err = -EFAULT; 207 208 out_kfree: 209 kfree(opaque); 210 out: 211 return err; 212 } 213 214 static void virtblk_prepare_flush(struct request_queue *q, struct request *req) 215 { 216 req->cmd_type = REQ_TYPE_LINUX_BLOCK; 217 req->cmd[0] = REQ_LB_OP_FLUSH; 218 } 219 220 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 221 unsigned cmd, unsigned long data) 222 { 223 struct gendisk *disk = bdev->bd_disk; 224 struct virtio_blk *vblk = disk->private_data; 225 void __user *argp = (void __user *)data; 226 227 if (cmd == HDIO_GET_IDENTITY) 228 return virtblk_identify(disk, argp); 229 230 /* 231 * Only allow the generic SCSI ioctls if the host can support it. 232 */ 233 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 234 return -ENOTTY; 235 236 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, argp); 237 } 238 239 /* We provide getgeo only to please some old bootloader/partitioning tools */ 240 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 241 { 242 struct virtio_blk *vblk = bd->bd_disk->private_data; 243 struct virtio_blk_geometry vgeo; 244 int err; 245 246 /* see if the host passed in geometry config */ 247 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 248 offsetof(struct virtio_blk_config, geometry), 249 &vgeo); 250 251 if (!err) { 252 geo->heads = vgeo.heads; 253 geo->sectors = vgeo.sectors; 254 geo->cylinders = vgeo.cylinders; 255 } else { 256 /* some standard values, similar to sd */ 257 geo->heads = 1 << 6; 258 geo->sectors = 1 << 5; 259 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 260 } 261 return 0; 262 } 263 264 static const struct block_device_operations virtblk_fops = { 265 .locked_ioctl = virtblk_ioctl, 266 .owner = THIS_MODULE, 267 .getgeo = virtblk_getgeo, 268 }; 269 270 static int index_to_minor(int index) 271 { 272 return index << PART_BITS; 273 } 274 275 static int __devinit virtblk_probe(struct virtio_device *vdev) 276 { 277 struct virtio_blk *vblk; 278 int err; 279 u64 cap; 280 u32 v; 281 u32 blk_size, sg_elems; 282 283 if (index_to_minor(index) >= 1 << MINORBITS) 284 return -ENOSPC; 285 286 /* We need to know how many segments before we allocate. */ 287 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 288 offsetof(struct virtio_blk_config, seg_max), 289 &sg_elems); 290 if (err) 291 sg_elems = 1; 292 293 /* We need an extra sg elements at head and tail. */ 294 sg_elems += 2; 295 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 296 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 297 if (!vblk) { 298 err = -ENOMEM; 299 goto out; 300 } 301 302 INIT_LIST_HEAD(&vblk->reqs); 303 spin_lock_init(&vblk->lock); 304 vblk->vdev = vdev; 305 vblk->sg_elems = sg_elems; 306 sg_init_table(vblk->sg, vblk->sg_elems); 307 308 /* We expect one virtqueue, for output. */ 309 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 310 if (IS_ERR(vblk->vq)) { 311 err = PTR_ERR(vblk->vq); 312 goto out_free_vblk; 313 } 314 315 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 316 if (!vblk->pool) { 317 err = -ENOMEM; 318 goto out_free_vq; 319 } 320 321 /* FIXME: How many partitions? How long is a piece of string? */ 322 vblk->disk = alloc_disk(1 << PART_BITS); 323 if (!vblk->disk) { 324 err = -ENOMEM; 325 goto out_mempool; 326 } 327 328 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 329 if (!vblk->disk->queue) { 330 err = -ENOMEM; 331 goto out_put_disk; 332 } 333 334 vblk->disk->queue->queuedata = vblk; 335 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, vblk->disk->queue); 336 337 if (index < 26) { 338 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 339 } else if (index < (26 + 1) * 26) { 340 sprintf(vblk->disk->disk_name, "vd%c%c", 341 'a' + index / 26 - 1, 'a' + index % 26); 342 } else { 343 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 344 const unsigned int m2 = (index / 26 - 1) % 26; 345 const unsigned int m3 = index % 26; 346 sprintf(vblk->disk->disk_name, "vd%c%c%c", 347 'a' + m1, 'a' + m2, 'a' + m3); 348 } 349 350 vblk->disk->major = major; 351 vblk->disk->first_minor = index_to_minor(index); 352 vblk->disk->private_data = vblk; 353 vblk->disk->fops = &virtblk_fops; 354 vblk->disk->driverfs_dev = &vdev->dev; 355 index++; 356 357 /* If barriers are supported, tell block layer that queue is ordered */ 358 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) 359 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH, 360 virtblk_prepare_flush); 361 else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) 362 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); 363 364 /* If disk is read-only in the host, the guest should obey */ 365 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 366 set_disk_ro(vblk->disk, 1); 367 368 /* Host must always specify the capacity. */ 369 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 370 &cap, sizeof(cap)); 371 372 /* If capacity is too big, truncate with warning. */ 373 if ((sector_t)cap != cap) { 374 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 375 (unsigned long long)cap); 376 cap = (sector_t)-1; 377 } 378 set_capacity(vblk->disk, cap); 379 380 /* We can handle whatever the host told us to handle. */ 381 blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); 382 blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); 383 384 /* No need to bounce any requests */ 385 blk_queue_bounce_limit(vblk->disk->queue, BLK_BOUNCE_ANY); 386 387 /* No real sector limit. */ 388 blk_queue_max_sectors(vblk->disk->queue, -1U); 389 390 /* Host can optionally specify maximum segment size and number of 391 * segments. */ 392 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 393 offsetof(struct virtio_blk_config, size_max), 394 &v); 395 if (!err) 396 blk_queue_max_segment_size(vblk->disk->queue, v); 397 else 398 blk_queue_max_segment_size(vblk->disk->queue, -1U); 399 400 /* Host can optionally specify the block size of the device */ 401 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 402 offsetof(struct virtio_blk_config, blk_size), 403 &blk_size); 404 if (!err) 405 blk_queue_logical_block_size(vblk->disk->queue, blk_size); 406 407 add_disk(vblk->disk); 408 return 0; 409 410 out_put_disk: 411 put_disk(vblk->disk); 412 out_mempool: 413 mempool_destroy(vblk->pool); 414 out_free_vq: 415 vdev->config->del_vqs(vdev); 416 out_free_vblk: 417 kfree(vblk); 418 out: 419 return err; 420 } 421 422 static void __devexit virtblk_remove(struct virtio_device *vdev) 423 { 424 struct virtio_blk *vblk = vdev->priv; 425 426 /* Nothing should be pending. */ 427 BUG_ON(!list_empty(&vblk->reqs)); 428 429 /* Stop all the virtqueues. */ 430 vdev->config->reset(vdev); 431 432 del_gendisk(vblk->disk); 433 blk_cleanup_queue(vblk->disk->queue); 434 put_disk(vblk->disk); 435 mempool_destroy(vblk->pool); 436 vdev->config->del_vqs(vdev); 437 kfree(vblk); 438 } 439 440 static struct virtio_device_id id_table[] = { 441 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 442 { 0 }, 443 }; 444 445 static unsigned int features[] = { 446 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 447 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 448 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_IDENTIFY, VIRTIO_BLK_F_FLUSH 449 }; 450 451 /* 452 * virtio_blk causes spurious section mismatch warning by 453 * simultaneously referring to a __devinit and a __devexit function. 454 * Use __refdata to avoid this warning. 455 */ 456 static struct virtio_driver __refdata virtio_blk = { 457 .feature_table = features, 458 .feature_table_size = ARRAY_SIZE(features), 459 .driver.name = KBUILD_MODNAME, 460 .driver.owner = THIS_MODULE, 461 .id_table = id_table, 462 .probe = virtblk_probe, 463 .remove = __devexit_p(virtblk_remove), 464 }; 465 466 static int __init init(void) 467 { 468 major = register_blkdev(0, "virtblk"); 469 if (major < 0) 470 return major; 471 return register_virtio_driver(&virtio_blk); 472 } 473 474 static void __exit fini(void) 475 { 476 unregister_blkdev(major, "virtblk"); 477 unregister_virtio_driver(&virtio_blk); 478 } 479 module_init(init); 480 module_exit(fini); 481 482 MODULE_DEVICE_TABLE(virtio, id_table); 483 MODULE_DESCRIPTION("Virtio block driver"); 484 MODULE_LICENSE("GPL"); 485