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