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 up_interval;
  30         unsigned down_interval;
  31         unsigned long flags;
  32         unsigned corrupt_bio_byte;
  33         unsigned corrupt_bio_rw;
  34         unsigned corrupt_bio_value;
  35         unsigned 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 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 (arg_name && !strcasecmp(arg_name, "w"))
 128                                 fc->corrupt_bio_rw = WRITE;
 129                         else if (arg_name && !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                         r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
 149                         if (r)
 150                                 return r;
 151                         argc--;
 152
 153                         continue;
 154                 }
 155
 156                 ti->error = "Unrecognised flakey feature requested";
 157                 return -EINVAL;
 158         }
 159
 160         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 161                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 162                 return -EINVAL;
 163
 164         } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 165                 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 166                 return -EINVAL;
 167         }
 168
 169         return 0;
 170 }
 171
 172 /*
 173  * Construct a flakey mapping:
 174  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 175  *
 176  *   Feature args:
 177  *     [drop_writes]
 178  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 179  *
 180  *   Nth_byte starts from 1 for the first byte.
 181  *   Direction is r for READ or w for WRITE.
 182  *   bio_flags is ignored if 0.
 183  */
 184 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 185 {
 186         static const struct dm_arg _args[] = {
 187                 {0, UINT_MAX, "Invalid up interval"},
 188                 {0, UINT_MAX, "Invalid down interval"},
 189         };
 190
 191         int r;
 192         struct flakey_c *fc;
 193         unsigned long long tmpll;
 194         struct dm_arg_set as;
 195         const char *devname;
 196         char dummy;
 197
 198         as.argc = argc;
 199         as.argv = argv;
 200
 201         if (argc < 4) {
 202                 ti->error = "Invalid argument count";
 203                 return -EINVAL;
 204         }
 205
 206         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 207         if (!fc) {
 208                 ti->error = "Cannot allocate context";
 209                 return -ENOMEM;
 210         }
 211         fc->start_time = jiffies;
 212
 213         devname = dm_shift_arg(&as);
 214
 215         r = -EINVAL;
 216         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
 217                 ti->error = "Invalid device sector";
 218                 goto bad;
 219         }
 220         fc->start = tmpll;
 221
 222         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 223         if (r)
 224                 goto bad;
 225
 226         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 227         if (r)
 228                 goto bad;
 229
 230         if (!(fc->up_interval + fc->down_interval)) {
 231                 ti->error = "Total (up + down) interval is zero";
 232                 r = -EINVAL;
 233                 goto bad;
 234         }
 235
 236         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 237                 ti->error = "Interval overflow";
 238                 r = -EINVAL;
 239                 goto bad;
 240         }
 241
 242         r = parse_features(&as, fc, ti);
 243         if (r)
 244                 goto bad;
 245
 246         r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
 247         if (r) {
 248                 ti->error = "Device lookup failed";
 249                 goto bad;
 250         }
 251
 252         ti->num_flush_bios = 1;
 253         ti->num_discard_bios = 1;
 254         ti->per_io_data_size = sizeof(struct per_bio_data);
 255         ti->private = fc;
 256         return 0;
 257
 258 bad:
 259         kfree(fc);
 260         return r;
 261 }
 262
 263 static void flakey_dtr(struct dm_target *ti)
 264 {
 265         struct flakey_c *fc = ti->private;
 266
 267         dm_put_device(ti, fc->dev);
 268         kfree(fc);
 269 }
 270
 271 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 272 {
 273         struct flakey_c *fc = ti->private;
 274
 275         return fc->start + dm_target_offset(ti, bi_sector);
 276 }
 277
 278 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 279 {
 280         struct flakey_c *fc = ti->private;
 281
 282         bio_set_dev(bio, fc->dev->bdev);
 283         if (bio_sectors(bio) || op_is_zone_mgmt(bio_op(bio)))
 284                 bio->bi_iter.bi_sector =
 285                         flakey_map_sector(ti, bio->bi_iter.bi_sector);
 286 }
 287
 288 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 289 {
 290         unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
 291
 292         struct bvec_iter iter;
 293         struct bio_vec bvec;
 294
 295         if (!bio_has_data(bio))
 296                 return;
 297
 298         /*
 299          * Overwrite the Nth byte of the bio's data, on whichever page
 300          * it falls.
 301          */
 302         bio_for_each_segment(bvec, bio, iter) {
 303                 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
 304                         char *segment;
 305                         struct page *page = bio_iter_page(bio, iter);
 306                         if (unlikely(page == ZERO_PAGE(0)))
 307                                 break;
 308                         segment = (page_address(page) + bio_iter_offset(bio, iter));
 309                         segment[corrupt_bio_byte] = fc->corrupt_bio_value;
 310                         DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 311                                 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
 312                                 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 313                                 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
 314                                 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 315                         break;
 316                 }
 317                 corrupt_bio_byte -= bio_iter_len(bio, iter);
 318         }
 319 }
 320
 321 static int flakey_map(struct dm_target *ti, struct bio *bio)
 322 {
 323         struct flakey_c *fc = ti->private;
 324         unsigned elapsed;
 325         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 326         pb->bio_submitted = false;
 327
 328         if (op_is_zone_mgmt(bio_op(bio)))
 329                 goto map_bio;
 330
 331         /* Are we alive ? */
 332         elapsed = (jiffies - fc->start_time) / HZ;
 333         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 334                 /*
 335                  * Flag this bio as submitted while down.
 336                  */
 337                 pb->bio_submitted = true;
 338
 339                 /*
 340                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
 341                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
 342                  */
 343                 if (bio_data_dir(bio) == READ) {
 344                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 345                             !test_bit(ERROR_WRITES, &fc->flags))
 346                                 return DM_MAPIO_KILL;
 347                         goto map_bio;
 348                 }
 349
 350                 /*
 351                  * Drop or error writes?
 352                  */
 353                 if (test_bit(DROP_WRITES, &fc->flags)) {
 354                         bio_endio(bio);
 355                         return DM_MAPIO_SUBMITTED;
 356                 }
 357                 else if (test_bit(ERROR_WRITES, &fc->flags)) {
 358                         bio_io_error(bio);
 359                         return DM_MAPIO_SUBMITTED;
 360                 }
 361
 362                 /*
 363                  * Corrupt matching writes.
 364                  */
 365                 if (fc->corrupt_bio_byte) {
 366                         if (fc->corrupt_bio_rw == WRITE) {
 367                                 if (all_corrupt_bio_flags_match(bio, fc))
 368                                         corrupt_bio_data(bio, fc);
 369                         }
 370                         goto map_bio;
 371                 }
 372
 373                 /*
 374                  * By default, error all I/O.
 375                  */
 376                 return DM_MAPIO_KILL;
 377         }
 378
 379 map_bio:
 380         flakey_map_bio(ti, bio);
 381
 382         return DM_MAPIO_REMAPPED;
 383 }
 384
 385 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 386                          blk_status_t *error)
 387 {
 388         struct flakey_c *fc = ti->private;
 389         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 390
 391         if (op_is_zone_mgmt(bio_op(bio)))
 392                 return DM_ENDIO_DONE;
 393
 394         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 395                 if (fc->corrupt_bio_byte) {
 396                         if ((fc->corrupt_bio_rw == READ) &&
 397                             all_corrupt_bio_flags_match(bio, fc)) {
 398                                 /*
 399                                  * Corrupt successful matching READs while in down state.
 400                                  */
 401                                 corrupt_bio_data(bio, fc);
 402                         }
 403                 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
 404                            !test_bit(ERROR_WRITES, &fc->flags)) {
 405                         /*
 406                          * Error read during the down_interval if drop_writes
 407                          * and error_writes were not configured.
 408                          */
 409                         *error = BLK_STS_IOERR;
 410                 }
 411         }
 412
 413         return DM_ENDIO_DONE;
 414 }
 415
 416 static void flakey_status(struct dm_target *ti, status_type_t type,
 417                           unsigned status_flags, char *result, unsigned maxlen)
 418 {
 419         unsigned sz = 0;
 420         struct flakey_c *fc = ti->private;
 421         unsigned drop_writes, error_writes;
 422
 423         switch (type) {
 424         case STATUSTYPE_INFO:
 425                 result[0] = '\0';
 426                 break;
 427
 428         case STATUSTYPE_TABLE:
 429                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 430                        (unsigned long long)fc->start, fc->up_interval,
 431                        fc->down_interval);
 432
 433                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 434                 error_writes = test_bit(ERROR_WRITES, &fc->flags);
 435                 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
 436
 437                 if (drop_writes)
 438                         DMEMIT("drop_writes ");
 439                 else if (error_writes)
 440                         DMEMIT("error_writes ");
 441
 442                 if (fc->corrupt_bio_byte)
 443                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 444                                fc->corrupt_bio_byte,
 445                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 446                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 447
 448                 break;
 449         }
 450 }
 451
 452 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 453 {
 454         struct flakey_c *fc = ti->private;
 455
 456         *bdev = fc->dev->bdev;
 457
 458         /*
 459          * Only pass ioctls through if the device sizes match exactly.
 460          */
 461         if (fc->start ||
 462             ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
 463                 return 1;
 464         return 0;
 465 }
 466
 467 #ifdef CONFIG_BLK_DEV_ZONED
 468 static int flakey_report_zones(struct dm_target *ti,
 469                 struct dm_report_zones_args *args, unsigned int nr_zones)
 470 {
 471         struct flakey_c *fc = ti->private;
 472         sector_t sector = flakey_map_sector(ti, args->next_sector);
 473
 474         args->start = fc->start;
 475         return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
 476                                    dm_report_zones_cb, args);
 477 }
 478 #endif
 479
 480 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 481 {
 482         struct flakey_c *fc = ti->private;
 483
 484         return fn(ti, fc->dev, fc->start, ti->len, data);
 485 }
 486
 487 static struct target_type flakey_target = {
 488         .name   = "flakey",
 489         .version = {1, 5, 0},
 490 #ifdef CONFIG_BLK_DEV_ZONED
 491         .features = DM_TARGET_ZONED_HM,
 492         .report_zones = flakey_report_zones,
 493 #endif
 494         .module = THIS_MODULE,
 495         .ctr    = flakey_ctr,
 496         .dtr    = flakey_dtr,
 497         .map    = flakey_map,
 498         .end_io = flakey_end_io,
 499         .status = flakey_status,
 500         .prepare_ioctl = flakey_prepare_ioctl,
 501         .iterate_devices = flakey_iterate_devices,
 502 };
 503
 504 static int __init dm_flakey_init(void)
 505 {
 506         int r = dm_register_target(&flakey_target);
 507
 508         if (r < 0)
 509                 DMERR("register failed %d", r);
 510
 511         return r;
 512 }
 513
 514 static void __exit dm_flakey_exit(void)
 515 {
 516         dm_unregister_target(&flakey_target);
 517 }
 518
 519 /* Module hooks */
 520 module_init(dm_flakey_init);
 521 module_exit(dm_flakey_exit);
 522
 523 MODULE_DESCRIPTION(DM_NAME " flakey target");
 524 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 525 MODULE_LICENSE("GPL");