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 (!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                         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         bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
 284 }
 285
 286 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 287 {
 288         unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
 289
 290         struct bvec_iter iter;
 291         struct bio_vec bvec;
 292
 293         if (!bio_has_data(bio))
 294                 return;
 295
 296         /*
 297          * Overwrite the Nth byte of the bio's data, on whichever page
 298          * it falls.
 299          */
 300         bio_for_each_segment(bvec, bio, iter) {
 301                 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
 302                         char *segment = (page_address(bio_iter_page(bio, iter))
 303                                          + bio_iter_offset(bio, iter));
 304                         segment[corrupt_bio_byte] = fc->corrupt_bio_value;
 305                         DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 306                                 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
 307                                 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 308                                 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
 309                                 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 310                         break;
 311                 }
 312                 corrupt_bio_byte -= bio_iter_len(bio, iter);
 313         }
 314 }
 315
 316 static int flakey_map(struct dm_target *ti, struct bio *bio)
 317 {
 318         struct flakey_c *fc = ti->private;
 319         unsigned elapsed;
 320         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 321         pb->bio_submitted = false;
 322
 323         if (op_is_zone_mgmt(bio_op(bio)))
 324                 goto map_bio;
 325
 326         /* Are we alive ? */
 327         elapsed = (jiffies - fc->start_time) / HZ;
 328         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 329                 /*
 330                  * Flag this bio as submitted while down.
 331                  */
 332                 pb->bio_submitted = true;
 333
 334                 /*
 335                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
 336                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
 337                  */
 338                 if (bio_data_dir(bio) == READ) {
 339                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 340                             !test_bit(ERROR_WRITES, &fc->flags))
 341                                 return DM_MAPIO_KILL;
 342                         goto map_bio;
 343                 }
 344
 345                 /*
 346                  * Drop or error writes?
 347                  */
 348                 if (test_bit(DROP_WRITES, &fc->flags)) {
 349                         bio_endio(bio);
 350                         return DM_MAPIO_SUBMITTED;
 351                 }
 352                 else if (test_bit(ERROR_WRITES, &fc->flags)) {
 353                         bio_io_error(bio);
 354                         return DM_MAPIO_SUBMITTED;
 355                 }
 356
 357                 /*
 358                  * Corrupt matching writes.
 359                  */
 360                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
 361                         if (all_corrupt_bio_flags_match(bio, fc))
 362                                 corrupt_bio_data(bio, fc);
 363                         goto map_bio;
 364                 }
 365
 366                 /*
 367                  * By default, error all I/O.
 368                  */
 369                 return DM_MAPIO_KILL;
 370         }
 371
 372 map_bio:
 373         flakey_map_bio(ti, bio);
 374
 375         return DM_MAPIO_REMAPPED;
 376 }
 377
 378 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 379                          blk_status_t *error)
 380 {
 381         struct flakey_c *fc = ti->private;
 382         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 383
 384         if (op_is_zone_mgmt(bio_op(bio)))
 385                 return DM_ENDIO_DONE;
 386
 387         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 388                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
 389                     all_corrupt_bio_flags_match(bio, fc)) {
 390                         /*
 391                          * Corrupt successful matching READs while in down state.
 392                          */
 393                         corrupt_bio_data(bio, fc);
 394
 395                 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
 396                            !test_bit(ERROR_WRITES, &fc->flags)) {
 397                         /*
 398                          * Error read during the down_interval if drop_writes
 399                          * and error_writes were not configured.
 400                          */
 401                         *error = BLK_STS_IOERR;
 402                 }
 403         }
 404
 405         return DM_ENDIO_DONE;
 406 }
 407
 408 static void flakey_status(struct dm_target *ti, status_type_t type,
 409                           unsigned status_flags, char *result, unsigned maxlen)
 410 {
 411         unsigned sz = 0;
 412         struct flakey_c *fc = ti->private;
 413         unsigned drop_writes, error_writes;
 414
 415         switch (type) {
 416         case STATUSTYPE_INFO:
 417                 result[0] = '\0';
 418                 break;
 419
 420         case STATUSTYPE_TABLE:
 421                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 422                        (unsigned long long)fc->start, fc->up_interval,
 423                        fc->down_interval);
 424
 425                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 426                 error_writes = test_bit(ERROR_WRITES, &fc->flags);
 427                 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
 428
 429                 if (drop_writes)
 430                         DMEMIT("drop_writes ");
 431                 else if (error_writes)
 432                         DMEMIT("error_writes ");
 433
 434                 if (fc->corrupt_bio_byte)
 435                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 436                                fc->corrupt_bio_byte,
 437                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 438                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 439
 440                 break;
 441
 442         case STATUSTYPE_IMA:
 443                 result[0] = '\0';
 444                 break;
 445         }
 446 }
 447
 448 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 449 {
 450         struct flakey_c *fc = ti->private;
 451
 452         *bdev = fc->dev->bdev;
 453
 454         /*
 455          * Only pass ioctls through if the device sizes match exactly.
 456          */
 457         if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
 458                 return 1;
 459         return 0;
 460 }
 461
 462 #ifdef CONFIG_BLK_DEV_ZONED
 463 static int flakey_report_zones(struct dm_target *ti,
 464                 struct dm_report_zones_args *args, unsigned int nr_zones)
 465 {
 466         struct flakey_c *fc = ti->private;
 467
 468         return dm_report_zones(fc->dev->bdev, fc->start,
 469                                flakey_map_sector(ti, args->next_sector),
 470                                args, nr_zones);
 471 }
 472 #else
 473 #define flakey_report_zones NULL
 474 #endif
 475
 476 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 477 {
 478         struct flakey_c *fc = ti->private;
 479
 480         return fn(ti, fc->dev, fc->start, ti->len, data);
 481 }
 482
 483 static struct target_type flakey_target = {
 484         .name   = "flakey",
 485         .version = {1, 5, 0},
 486         .features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
 487         .report_zones = flakey_report_zones,
 488         .module = THIS_MODULE,
 489         .ctr    = flakey_ctr,
 490         .dtr    = flakey_dtr,
 491         .map    = flakey_map,
 492         .end_io = flakey_end_io,
 493         .status = flakey_status,
 494         .prepare_ioctl = flakey_prepare_ioctl,
 495         .iterate_devices = flakey_iterate_devices,
 496 };
 497
 498 static int __init dm_flakey_init(void)
 499 {
 500         int r = dm_register_target(&flakey_target);
 501
 502         if (r < 0)
 503                 DMERR("register failed %d", r);
 504
 505         return r;
 506 }
 507
 508 static void __exit dm_flakey_exit(void)
 509 {
 510         dm_unregister_target(&flakey_target);
 511 }
 512
 513 /* Module hooks */
 514 module_init(dm_flakey_init);
 515 module_exit(dm_flakey_exit);
 516
 517 MODULE_DESCRIPTION(DM_NAME " flakey target");
 518 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 519 MODULE_LICENSE("GPL");