drivers/md/dm-flakey.c

   1 /*
   2  * Copyright (C) 2003 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/device-mapper.h>
   9
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/blkdev.h>
  13 #include <linux/bio.h>
  14 #include <linux/slab.h>
  15
  16 #define DM_MSG_PREFIX "flakey"
  17
  18 #define all_corrupt_bio_flags_match(bio, fc)    \
  19         (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
  20
  21 /*
  22  * Flakey: Used for testing only, simulates intermittent,
  23  * catastrophic device failure.
  24  */
  25 struct flakey_c {
  26         struct dm_dev *dev;
  27         unsigned long start_time;
  28         sector_t start;
  29         unsigned int up_interval;
  30         unsigned int down_interval;
  31         unsigned long flags;
  32         unsigned int corrupt_bio_byte;
  33         unsigned int corrupt_bio_rw;
  34         unsigned int corrupt_bio_value;
  35         blk_opf_t corrupt_bio_flags;
  36 };
  37
  38 enum feature_flag_bits {
  39         DROP_WRITES,
  40         ERROR_WRITES
  41 };
  42
  43 struct per_bio_data {
  44         bool bio_submitted;
  45 };
  46
  47 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
  48                           struct dm_target *ti)
  49 {
  50         int r;
  51         unsigned int argc;
  52         const char *arg_name;
  53
  54         static const struct dm_arg _args[] = {
  55                 {0, 6, "Invalid number of feature args"},
  56                 {1, UINT_MAX, "Invalid corrupt bio byte"},
  57                 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
  58                 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
  59         };
  60
  61         /* No feature arguments supplied. */
  62         if (!as->argc)
  63                 return 0;
  64
  65         r = dm_read_arg_group(_args, as, &argc, &ti->error);
  66         if (r)
  67                 return r;
  68
  69         while (argc) {
  70                 arg_name = dm_shift_arg(as);
  71                 argc--;
  72
  73                 if (!arg_name) {
  74                         ti->error = "Insufficient feature arguments";
  75                         return -EINVAL;
  76                 }
  77
  78                 /*
  79                  * drop_writes
  80                  */
  81                 if (!strcasecmp(arg_name, "drop_writes")) {
  82                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
  83                                 ti->error = "Feature drop_writes duplicated";
  84                                 return -EINVAL;
  85                         } else if (test_bit(ERROR_WRITES, &fc->flags)) {
  86                                 ti->error = "Feature drop_writes conflicts with feature error_writes";
  87                                 return -EINVAL;
  88                         }
  89
  90                         continue;
  91                 }
  92
  93                 /*
  94                  * error_writes
  95                  */
  96                 if (!strcasecmp(arg_name, "error_writes")) {
  97                         if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
  98                                 ti->error = "Feature error_writes duplicated";
  99                                 return -EINVAL;
 100
 101                         } else if (test_bit(DROP_WRITES, &fc->flags)) {
 102                                 ti->error = "Feature error_writes conflicts with feature drop_writes";
 103                                 return -EINVAL;
 104                         }
 105
 106                         continue;
 107                 }
 108
 109                 /*
 110                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
 111                  */
 112                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
 113                         if (!argc) {
 114                                 ti->error = "Feature corrupt_bio_byte requires parameters";
 115                                 return -EINVAL;
 116                         }
 117
 118                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
 119                         if (r)
 120                                 return r;
 121                         argc--;
 122
 123                         /*
 124                          * Direction r or w?
 125                          */
 126                         arg_name = dm_shift_arg(as);
 127                         if (!strcasecmp(arg_name, "w"))
 128                                 fc->corrupt_bio_rw = WRITE;
 129                         else if (!strcasecmp(arg_name, "r"))
 130                                 fc->corrupt_bio_rw = READ;
 131                         else {
 132                                 ti->error = "Invalid corrupt bio direction (r or w)";
 133                                 return -EINVAL;
 134                         }
 135                         argc--;
 136
 137                         /*
 138                          * Value of byte (0-255) to write in place of correct one.
 139                          */
 140                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
 141                         if (r)
 142                                 return r;
 143                         argc--;
 144
 145                         /*
 146                          * Only corrupt bios with these flags set.
 147                          */
 148                         BUILD_BUG_ON(sizeof(fc->corrupt_bio_flags) !=
 149                                      sizeof(unsigned int));
 150                         r = dm_read_arg(_args + 3, as,
 151                                 (__force unsigned int *)&fc->corrupt_bio_flags,
 152                                 &ti->error);
 153                         if (r)
 154                                 return r;
 155                         argc--;
 156
 157                         continue;
 158                 }
 159
 160                 ti->error = "Unrecognised flakey feature requested";
 161                 return -EINVAL;
 162         }
 163
 164         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 165                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 166                 return -EINVAL;
 167
 168         } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 169                 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 170                 return -EINVAL;
 171         }
 172
 173         return 0;
 174 }
 175
 176 /*
 177  * Construct a flakey mapping:
 178  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 179  *
 180  *   Feature args:
 181  *     [drop_writes]
 182  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 183  *
 184  *   Nth_byte starts from 1 for the first byte.
 185  *   Direction is r for READ or w for WRITE.
 186  *   bio_flags is ignored if 0.
 187  */
 188 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 189 {
 190         static const struct dm_arg _args[] = {
 191                 {0, UINT_MAX, "Invalid up interval"},
 192                 {0, UINT_MAX, "Invalid down interval"},
 193         };
 194
 195         int r;
 196         struct flakey_c *fc;
 197         unsigned long long tmpll;
 198         struct dm_arg_set as;
 199         const char *devname;
 200         char dummy;
 201
 202         as.argc = argc;
 203         as.argv = argv;
 204
 205         if (argc < 4) {
 206                 ti->error = "Invalid argument count";
 207                 return -EINVAL;
 208         }
 209
 210         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 211         if (!fc) {
 212                 ti->error = "Cannot allocate context";
 213                 return -ENOMEM;
 214         }
 215         fc->start_time = jiffies;
 216
 217         devname = dm_shift_arg(&as);
 218
 219         r = -EINVAL;
 220         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
 221                 ti->error = "Invalid device sector";
 222                 goto bad;
 223         }
 224         fc->start = tmpll;
 225
 226         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 227         if (r)
 228                 goto bad;
 229
 230         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 231         if (r)
 232                 goto bad;
 233
 234         if (!(fc->up_interval + fc->down_interval)) {
 235                 ti->error = "Total (up + down) interval is zero";
 236                 r = -EINVAL;
 237                 goto bad;
 238         }
 239
 240         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 241                 ti->error = "Interval overflow";
 242                 r = -EINVAL;
 243                 goto bad;
 244         }
 245
 246         r = parse_features(&as, fc, ti);
 247         if (r)
 248                 goto bad;
 249
 250         r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
 251         if (r) {
 252                 ti->error = "Device lookup failed";
 253                 goto bad;
 254         }
 255
 256         ti->num_flush_bios = 1;
 257         ti->num_discard_bios = 1;
 258         ti->per_io_data_size = sizeof(struct per_bio_data);
 259         ti->private = fc;
 260         return 0;
 261
 262 bad:
 263         kfree(fc);
 264         return r;
 265 }
 266
 267 static void flakey_dtr(struct dm_target *ti)
 268 {
 269         struct flakey_c *fc = ti->private;
 270
 271         dm_put_device(ti, fc->dev);
 272         kfree(fc);
 273 }
 274
 275 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 276 {
 277         struct flakey_c *fc = ti->private;
 278
 279         return fc->start + dm_target_offset(ti, bi_sector);
 280 }
 281
 282 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 283 {
 284         struct flakey_c *fc = ti->private;
 285
 286         bio_set_dev(bio, fc->dev->bdev);
 287         bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
 288 }
 289
 290 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 291 {
 292         unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
 293
 294         struct bvec_iter iter;
 295         struct bio_vec bvec;
 296
 297         if (!bio_has_data(bio))
 298                 return;
 299
 300         /*
 301          * Overwrite the Nth byte of the bio's data, on whichever page
 302          * it falls.
 303          */
 304         bio_for_each_segment(bvec, bio, iter) {
 305                 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
 306                         char *segment;
 307                         struct page *page = bio_iter_page(bio, iter);
 308                         if (unlikely(page == ZERO_PAGE(0)))
 309                                 break;
 310                         segment = bvec_kmap_local(&bvec);
 311                         segment[corrupt_bio_byte] = fc->corrupt_bio_value;
 312                         kunmap_local(segment);
 313                         DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 314                                 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
 315                                 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 316                                 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
 317                                 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 318                         break;
 319                 }
 320                 corrupt_bio_byte -= bio_iter_len(bio, iter);
 321         }
 322 }
 323
 324 static int flakey_map(struct dm_target *ti, struct bio *bio)
 325 {
 326         struct flakey_c *fc = ti->private;
 327         unsigned int elapsed;
 328         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 329         pb->bio_submitted = false;
 330
 331         if (op_is_zone_mgmt(bio_op(bio)))
 332                 goto map_bio;
 333
 334         /* Are we alive ? */
 335         elapsed = (jiffies - fc->start_time) / HZ;
 336         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 337                 /*
 338                  * Flag this bio as submitted while down.
 339                  */
 340                 pb->bio_submitted = true;
 341
 342                 /*
 343                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
 344                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
 345                  */
 346                 if (bio_data_dir(bio) == READ) {
 347                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 348                             !test_bit(ERROR_WRITES, &fc->flags))
 349                                 return DM_MAPIO_KILL;
 350                         goto map_bio;
 351                 }
 352
 353                 /*
 354                  * Drop or error writes?
 355                  */
 356                 if (test_bit(DROP_WRITES, &fc->flags)) {
 357                         bio_endio(bio);
 358                         return DM_MAPIO_SUBMITTED;
 359                 }
 360                 else if (test_bit(ERROR_WRITES, &fc->flags)) {
 361                         bio_io_error(bio);
 362                         return DM_MAPIO_SUBMITTED;
 363                 }
 364
 365                 /*
 366                  * Corrupt matching writes.
 367                  */
 368                 if (fc->corrupt_bio_byte) {
 369                         if (fc->corrupt_bio_rw == WRITE) {
 370                                 if (all_corrupt_bio_flags_match(bio, fc))
 371                                         corrupt_bio_data(bio, fc);
 372                         }
 373                         goto map_bio;
 374                 }
 375
 376                 /*
 377                  * By default, error all I/O.
 378                  */
 379                 return DM_MAPIO_KILL;
 380         }
 381
 382 map_bio:
 383         flakey_map_bio(ti, bio);
 384
 385         return DM_MAPIO_REMAPPED;
 386 }
 387
 388 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 389                          blk_status_t *error)
 390 {
 391         struct flakey_c *fc = ti->private;
 392         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 393
 394         if (op_is_zone_mgmt(bio_op(bio)))
 395                 return DM_ENDIO_DONE;
 396
 397         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 398                 if (fc->corrupt_bio_byte) {
 399                         if ((fc->corrupt_bio_rw == READ) &&
 400                             all_corrupt_bio_flags_match(bio, fc)) {
 401                                 /*
 402                                  * Corrupt successful matching READs while in down state.
 403                                  */
 404                                 corrupt_bio_data(bio, fc);
 405                         }
 406                 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
 407                            !test_bit(ERROR_WRITES, &fc->flags)) {
 408                         /*
 409                          * Error read during the down_interval if drop_writes
 410                          * and error_writes were not configured.
 411                          */
 412                         *error = BLK_STS_IOERR;
 413                 }
 414         }
 415
 416         return DM_ENDIO_DONE;
 417 }
 418
 419 static void flakey_status(struct dm_target *ti, status_type_t type,
 420                           unsigned int status_flags, char *result, unsigned int maxlen)
 421 {
 422         unsigned int sz = 0;
 423         struct flakey_c *fc = ti->private;
 424         unsigned int drop_writes, error_writes;
 425
 426         switch (type) {
 427         case STATUSTYPE_INFO:
 428                 result[0] = '\0';
 429                 break;
 430
 431         case STATUSTYPE_TABLE:
 432                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 433                        (unsigned long long)fc->start, fc->up_interval,
 434                        fc->down_interval);
 435
 436                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 437                 error_writes = test_bit(ERROR_WRITES, &fc->flags);
 438                 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
 439
 440                 if (drop_writes)
 441                         DMEMIT("drop_writes ");
 442                 else if (error_writes)
 443                         DMEMIT("error_writes ");
 444
 445                 if (fc->corrupt_bio_byte)
 446                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 447                                fc->corrupt_bio_byte,
 448                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 449                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 450
 451                 break;
 452
 453         case STATUSTYPE_IMA:
 454                 result[0] = '\0';
 455                 break;
 456         }
 457 }
 458
 459 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 460 {
 461         struct flakey_c *fc = ti->private;
 462
 463         *bdev = fc->dev->bdev;
 464
 465         /*
 466          * Only pass ioctls through if the device sizes match exactly.
 467          */
 468         if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
 469                 return 1;
 470         return 0;
 471 }
 472
 473 #ifdef CONFIG_BLK_DEV_ZONED
 474 static int flakey_report_zones(struct dm_target *ti,
 475                 struct dm_report_zones_args *args, unsigned int nr_zones)
 476 {
 477         struct flakey_c *fc = ti->private;
 478
 479         return dm_report_zones(fc->dev->bdev, fc->start,
 480                                flakey_map_sector(ti, args->next_sector),
 481                                args, nr_zones);
 482 }
 483 #else
 484 #define flakey_report_zones NULL
 485 #endif
 486
 487 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 488 {
 489         struct flakey_c *fc = ti->private;
 490
 491         return fn(ti, fc->dev, fc->start, ti->len, data);
 492 }
 493
 494 static struct target_type flakey_target = {
 495         .name   = "flakey",
 496         .version = {1, 5, 0},
 497         .features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
 498         .report_zones = flakey_report_zones,
 499         .module = THIS_MODULE,
 500         .ctr    = flakey_ctr,
 501         .dtr    = flakey_dtr,
 502         .map    = flakey_map,
 503         .end_io = flakey_end_io,
 504         .status = flakey_status,
 505         .prepare_ioctl = flakey_prepare_ioctl,
 506         .iterate_devices = flakey_iterate_devices,
 507 };
 508
 509 static int __init dm_flakey_init(void)
 510 {
 511         int r = dm_register_target(&flakey_target);
 512
 513         if (r < 0)
 514                 DMERR("register failed %d", r);
 515
 516         return r;
 517 }
 518
 519 static void __exit dm_flakey_exit(void)
 520 {
 521         dm_unregister_target(&flakey_target);
 522 }
 523
 524 /* Module hooks */
 525 module_init(dm_flakey_init);
 526 module_exit(dm_flakey_exit);
 527
 528 MODULE_DESCRIPTION(DM_NAME " flakey target");
 529 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 530 MODULE_LICENSE("GPL");