drivers/md/dm-dust.c

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