1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2018 Red Hat, Inc. 4 * 5 * This is a test "dust" device, which fails reads on specified 6 * sectors, emulating the behavior of a hard disk drive sending 7 * a "Read Medium Error" sense. 8 * 9 */ 10 11 #include <linux/device-mapper.h> 12 #include <linux/module.h> 13 #include <linux/rbtree.h> 14 15 #define DM_MSG_PREFIX "dust" 16 17 struct badblock { 18 struct rb_node node; 19 sector_t bb; 20 unsigned char wr_fail_cnt; 21 }; 22 23 struct dust_device { 24 struct dm_dev *dev; 25 struct rb_root badblocklist; 26 unsigned long long badblock_count; 27 spinlock_t dust_lock; 28 unsigned int blksz; 29 int sect_per_block_shift; 30 unsigned int sect_per_block; 31 sector_t start; 32 bool fail_read_on_bb:1; 33 bool quiet_mode:1; 34 }; 35 36 static struct badblock *dust_rb_search(struct rb_root *root, sector_t blk) 37 { 38 struct rb_node *node = root->rb_node; 39 40 while (node) { 41 struct badblock *bblk = rb_entry(node, struct badblock, node); 42 43 if (bblk->bb > blk) 44 node = node->rb_left; 45 else if (bblk->bb < blk) 46 node = node->rb_right; 47 else 48 return bblk; 49 } 50 51 return NULL; 52 } 53 54 static bool dust_rb_insert(struct rb_root *root, struct badblock *new) 55 { 56 struct badblock *bblk; 57 struct rb_node **link = &root->rb_node, *parent = NULL; 58 sector_t value = new->bb; 59 60 while (*link) { 61 parent = *link; 62 bblk = rb_entry(parent, struct badblock, node); 63 64 if (bblk->bb > value) 65 link = &(*link)->rb_left; 66 else if (bblk->bb < value) 67 link = &(*link)->rb_right; 68 else 69 return false; 70 } 71 72 rb_link_node(&new->node, parent, link); 73 rb_insert_color(&new->node, root); 74 75 return true; 76 } 77 78 static int dust_remove_block(struct dust_device *dd, unsigned long long block) 79 { 80 struct badblock *bblock; 81 unsigned long flags; 82 83 spin_lock_irqsave(&dd->dust_lock, flags); 84 bblock = dust_rb_search(&dd->badblocklist, block); 85 86 if (bblock == NULL) { 87 if (!dd->quiet_mode) { 88 DMERR("%s: block %llu not found in badblocklist", 89 __func__, block); 90 } 91 spin_unlock_irqrestore(&dd->dust_lock, flags); 92 return -EINVAL; 93 } 94 95 rb_erase(&bblock->node, &dd->badblocklist); 96 dd->badblock_count--; 97 if (!dd->quiet_mode) 98 DMINFO("%s: badblock removed at block %llu", __func__, block); 99 kfree(bblock); 100 spin_unlock_irqrestore(&dd->dust_lock, flags); 101 102 return 0; 103 } 104 105 static int dust_add_block(struct dust_device *dd, unsigned long long block, 106 unsigned char wr_fail_cnt) 107 { 108 struct badblock *bblock; 109 unsigned long flags; 110 111 bblock = kmalloc(sizeof(*bblock), GFP_KERNEL); 112 if (bblock == NULL) { 113 if (!dd->quiet_mode) 114 DMERR("%s: badblock allocation failed", __func__); 115 return -ENOMEM; 116 } 117 118 spin_lock_irqsave(&dd->dust_lock, flags); 119 bblock->bb = block; 120 bblock->wr_fail_cnt = wr_fail_cnt; 121 if (!dust_rb_insert(&dd->badblocklist, bblock)) { 122 if (!dd->quiet_mode) { 123 DMERR("%s: block %llu already in badblocklist", 124 __func__, block); 125 } 126 spin_unlock_irqrestore(&dd->dust_lock, flags); 127 kfree(bblock); 128 return -EINVAL; 129 } 130 131 dd->badblock_count++; 132 if (!dd->quiet_mode) { 133 DMINFO("%s: badblock added at block %llu with write fail count %hhu", 134 __func__, block, wr_fail_cnt); 135 } 136 spin_unlock_irqrestore(&dd->dust_lock, flags); 137 138 return 0; 139 } 140 141 static int dust_query_block(struct dust_device *dd, unsigned long long block) 142 { 143 struct badblock *bblock; 144 unsigned long flags; 145 146 spin_lock_irqsave(&dd->dust_lock, flags); 147 bblock = dust_rb_search(&dd->badblocklist, block); 148 if (bblock != NULL) 149 DMINFO("%s: block %llu found in badblocklist", __func__, block); 150 else 151 DMINFO("%s: block %llu not found in badblocklist", __func__, block); 152 spin_unlock_irqrestore(&dd->dust_lock, flags); 153 154 return 0; 155 } 156 157 static int __dust_map_read(struct dust_device *dd, sector_t thisblock) 158 { 159 struct badblock *bblk = dust_rb_search(&dd->badblocklist, thisblock); 160 161 if (bblk) 162 return DM_MAPIO_KILL; 163 164 return DM_MAPIO_REMAPPED; 165 } 166 167 static int dust_map_read(struct dust_device *dd, sector_t thisblock, 168 bool fail_read_on_bb) 169 { 170 unsigned long flags; 171 int r = DM_MAPIO_REMAPPED; 172 173 if (fail_read_on_bb) { 174 thisblock >>= dd->sect_per_block_shift; 175 spin_lock_irqsave(&dd->dust_lock, flags); 176 r = __dust_map_read(dd, thisblock); 177 spin_unlock_irqrestore(&dd->dust_lock, flags); 178 } 179 180 return r; 181 } 182 183 static int __dust_map_write(struct dust_device *dd, sector_t thisblock) 184 { 185 struct badblock *bblk = dust_rb_search(&dd->badblocklist, thisblock); 186 187 if (bblk && bblk->wr_fail_cnt > 0) { 188 bblk->wr_fail_cnt--; 189 return DM_MAPIO_KILL; 190 } 191 192 if (bblk) { 193 rb_erase(&bblk->node, &dd->badblocklist); 194 dd->badblock_count--; 195 kfree(bblk); 196 if (!dd->quiet_mode) { 197 sector_div(thisblock, dd->sect_per_block); 198 DMINFO("block %llu removed from badblocklist by write", 199 (unsigned long long)thisblock); 200 } 201 } 202 203 return DM_MAPIO_REMAPPED; 204 } 205 206 static int dust_map_write(struct dust_device *dd, sector_t thisblock, 207 bool fail_read_on_bb) 208 { 209 unsigned long flags; 210 int ret = DM_MAPIO_REMAPPED; 211 212 if (fail_read_on_bb) { 213 thisblock >>= dd->sect_per_block_shift; 214 spin_lock_irqsave(&dd->dust_lock, flags); 215 ret = __dust_map_write(dd, thisblock); 216 spin_unlock_irqrestore(&dd->dust_lock, flags); 217 } 218 219 return ret; 220 } 221 222 static int dust_map(struct dm_target *ti, struct bio *bio) 223 { 224 struct dust_device *dd = ti->private; 225 int r; 226 227 bio_set_dev(bio, dd->dev->bdev); 228 bio->bi_iter.bi_sector = dd->start + dm_target_offset(ti, bio->bi_iter.bi_sector); 229 230 if (bio_data_dir(bio) == READ) 231 r = dust_map_read(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb); 232 else 233 r = dust_map_write(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb); 234 235 return r; 236 } 237 238 static bool __dust_clear_badblocks(struct rb_root *tree, 239 unsigned long long count) 240 { 241 struct rb_node *node = NULL, *nnode = NULL; 242 243 nnode = rb_first(tree); 244 if (nnode == NULL) { 245 BUG_ON(count != 0); 246 return false; 247 } 248 249 while (nnode) { 250 node = nnode; 251 nnode = rb_next(node); 252 rb_erase(node, tree); 253 count--; 254 kfree(node); 255 } 256 BUG_ON(count != 0); 257 BUG_ON(tree->rb_node != NULL); 258 259 return true; 260 } 261 262 static int dust_clear_badblocks(struct dust_device *dd) 263 { 264 unsigned long flags; 265 struct rb_root badblocklist; 266 unsigned long long badblock_count; 267 268 spin_lock_irqsave(&dd->dust_lock, flags); 269 badblocklist = dd->badblocklist; 270 badblock_count = dd->badblock_count; 271 dd->badblocklist = RB_ROOT; 272 dd->badblock_count = 0; 273 spin_unlock_irqrestore(&dd->dust_lock, flags); 274 275 if (!__dust_clear_badblocks(&badblocklist, badblock_count)) 276 DMINFO("%s: no badblocks found", __func__); 277 else 278 DMINFO("%s: badblocks cleared", __func__); 279 280 return 0; 281 } 282 283 /* 284 * Target parameters: 285 * 286 * <device_path> <offset> <blksz> 287 * 288 * device_path: path to the block device 289 * offset: offset to data area from start of device_path 290 * blksz: block size (minimum 512, maximum 1073741824, must be a power of 2) 291 */ 292 static int dust_ctr(struct dm_target *ti, unsigned int argc, char **argv) 293 { 294 struct dust_device *dd; 295 unsigned long long tmp; 296 char dummy; 297 unsigned int blksz; 298 unsigned int sect_per_block; 299 sector_t DUST_MAX_BLKSZ_SECTORS = 2097152; 300 sector_t max_block_sectors = min(ti->len, DUST_MAX_BLKSZ_SECTORS); 301 302 if (argc != 3) { 303 ti->error = "Invalid argument count"; 304 return -EINVAL; 305 } 306 307 if (kstrtouint(argv[2], 10, &blksz) || !blksz) { 308 ti->error = "Invalid block size parameter"; 309 return -EINVAL; 310 } 311 312 if (blksz < 512) { 313 ti->error = "Block size must be at least 512"; 314 return -EINVAL; 315 } 316 317 if (!is_power_of_2(blksz)) { 318 ti->error = "Block size must be a power of 2"; 319 return -EINVAL; 320 } 321 322 if (to_sector(blksz) > max_block_sectors) { 323 ti->error = "Block size is too large"; 324 return -EINVAL; 325 } 326 327 sect_per_block = (blksz >> SECTOR_SHIFT); 328 329 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) { 330 ti->error = "Invalid device offset sector"; 331 return -EINVAL; 332 } 333 334 dd = kzalloc(sizeof(struct dust_device), GFP_KERNEL); 335 if (dd == NULL) { 336 ti->error = "Cannot allocate context"; 337 return -ENOMEM; 338 } 339 340 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dd->dev)) { 341 ti->error = "Device lookup failed"; 342 kfree(dd); 343 return -EINVAL; 344 } 345 346 dd->sect_per_block = sect_per_block; 347 dd->blksz = blksz; 348 dd->start = tmp; 349 350 dd->sect_per_block_shift = __ffs(sect_per_block); 351 352 /* 353 * Whether to fail a read on a "bad" block. 354 * Defaults to false; enabled later by message. 355 */ 356 dd->fail_read_on_bb = false; 357 358 /* 359 * Initialize bad block list rbtree. 360 */ 361 dd->badblocklist = RB_ROOT; 362 dd->badblock_count = 0; 363 spin_lock_init(&dd->dust_lock); 364 365 dd->quiet_mode = false; 366 367 BUG_ON(dm_set_target_max_io_len(ti, dd->sect_per_block) != 0); 368 369 ti->num_discard_bios = 1; 370 ti->num_flush_bios = 1; 371 ti->private = dd; 372 373 return 0; 374 } 375 376 static void dust_dtr(struct dm_target *ti) 377 { 378 struct dust_device *dd = ti->private; 379 380 __dust_clear_badblocks(&dd->badblocklist, dd->badblock_count); 381 dm_put_device(ti, dd->dev); 382 kfree(dd); 383 } 384 385 static int dust_message(struct dm_target *ti, unsigned int argc, char **argv, 386 char *result_buf, unsigned int maxlen) 387 { 388 struct dust_device *dd = ti->private; 389 sector_t size = i_size_read(dd->dev->bdev->bd_inode) >> SECTOR_SHIFT; 390 bool invalid_msg = false; 391 int r = -EINVAL; 392 unsigned long long tmp, block; 393 unsigned char wr_fail_cnt; 394 unsigned int tmp_ui; 395 unsigned long flags; 396 char dummy; 397 398 if (argc == 1) { 399 if (!strcasecmp(argv[0], "addbadblock") || 400 !strcasecmp(argv[0], "removebadblock") || 401 !strcasecmp(argv[0], "queryblock")) { 402 DMERR("%s requires an additional argument", argv[0]); 403 } else if (!strcasecmp(argv[0], "disable")) { 404 DMINFO("disabling read failures on bad sectors"); 405 dd->fail_read_on_bb = false; 406 r = 0; 407 } else if (!strcasecmp(argv[0], "enable")) { 408 DMINFO("enabling read failures on bad sectors"); 409 dd->fail_read_on_bb = true; 410 r = 0; 411 } else if (!strcasecmp(argv[0], "countbadblocks")) { 412 spin_lock_irqsave(&dd->dust_lock, flags); 413 DMINFO("countbadblocks: %llu badblock(s) found", 414 dd->badblock_count); 415 spin_unlock_irqrestore(&dd->dust_lock, flags); 416 r = 0; 417 } else if (!strcasecmp(argv[0], "clearbadblocks")) { 418 r = dust_clear_badblocks(dd); 419 } else if (!strcasecmp(argv[0], "quiet")) { 420 if (!dd->quiet_mode) 421 dd->quiet_mode = true; 422 else 423 dd->quiet_mode = false; 424 r = 0; 425 } else { 426 invalid_msg = true; 427 } 428 } else if (argc == 2) { 429 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) 430 return r; 431 432 block = tmp; 433 sector_div(size, dd->sect_per_block); 434 if (block > size) { 435 DMERR("selected block value out of range"); 436 return r; 437 } 438 439 if (!strcasecmp(argv[0], "addbadblock")) 440 r = dust_add_block(dd, block, 0); 441 else if (!strcasecmp(argv[0], "removebadblock")) 442 r = dust_remove_block(dd, block); 443 else if (!strcasecmp(argv[0], "queryblock")) 444 r = dust_query_block(dd, block); 445 else 446 invalid_msg = true; 447 448 } else if (argc == 3) { 449 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) 450 return r; 451 452 if (sscanf(argv[2], "%u%c", &tmp_ui, &dummy) != 1) 453 return r; 454 455 block = tmp; 456 if (tmp_ui > 255) { 457 DMERR("selected write fail count out of range"); 458 return r; 459 } 460 wr_fail_cnt = tmp_ui; 461 sector_div(size, dd->sect_per_block); 462 if (block > size) { 463 DMERR("selected block value out of range"); 464 return r; 465 } 466 467 if (!strcasecmp(argv[0], "addbadblock")) 468 r = dust_add_block(dd, block, wr_fail_cnt); 469 else 470 invalid_msg = true; 471 472 } else 473 DMERR("invalid number of arguments '%d'", argc); 474 475 if (invalid_msg) 476 DMERR("unrecognized message '%s' received", argv[0]); 477 478 return r; 479 } 480 481 static void dust_status(struct dm_target *ti, status_type_t type, 482 unsigned int status_flags, char *result, unsigned int maxlen) 483 { 484 struct dust_device *dd = ti->private; 485 unsigned int sz = 0; 486 487 switch (type) { 488 case STATUSTYPE_INFO: 489 DMEMIT("%s %s %s", dd->dev->name, 490 dd->fail_read_on_bb ? "fail_read_on_bad_block" : "bypass", 491 dd->quiet_mode ? "quiet" : "verbose"); 492 break; 493 494 case STATUSTYPE_TABLE: 495 DMEMIT("%s %llu %u", dd->dev->name, 496 (unsigned long long)dd->start, dd->blksz); 497 break; 498 } 499 } 500 501 static int dust_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 502 { 503 struct dust_device *dd = ti->private; 504 struct dm_dev *dev = dd->dev; 505 506 *bdev = dev->bdev; 507 508 /* 509 * Only pass ioctls through if the device sizes match exactly. 510 */ 511 if (dd->start || 512 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 513 return 1; 514 515 return 0; 516 } 517 518 static int dust_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, 519 void *data) 520 { 521 struct dust_device *dd = ti->private; 522 523 return fn(ti, dd->dev, dd->start, ti->len, data); 524 } 525 526 static struct target_type dust_target = { 527 .name = "dust", 528 .version = {1, 0, 0}, 529 .module = THIS_MODULE, 530 .ctr = dust_ctr, 531 .dtr = dust_dtr, 532 .iterate_devices = dust_iterate_devices, 533 .map = dust_map, 534 .message = dust_message, 535 .status = dust_status, 536 .prepare_ioctl = dust_prepare_ioctl, 537 }; 538 539 static int __init dm_dust_init(void) 540 { 541 int r = dm_register_target(&dust_target); 542 543 if (r < 0) 544 DMERR("dm_register_target failed %d", r); 545 546 return r; 547 } 548 549 static void __exit dm_dust_exit(void) 550 { 551 dm_unregister_target(&dust_target); 552 } 553 554 module_init(dm_dust_init); 555 module_exit(dm_dust_exit); 556 557 MODULE_DESCRIPTION(DM_NAME " dust test target"); 558 MODULE_AUTHOR("Bryan Gurney <dm-devel@redhat.com>"); 559 MODULE_LICENSE("GPL"); 560