drivers/md/dm-flakey.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2003 Sistina Software (UK) Limited.
   4  * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
   5  *
   6  * This file is released under the GPL.
   7  */
   8
   9 #include <linux/device-mapper.h>
  10
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/bio.h>
  15 #include <linux/slab.h>
  16
  17 #define DM_MSG_PREFIX "flakey"
  18
  19 #define all_corrupt_bio_flags_match(bio, fc)    \
  20         (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
  21
  22 /*
  23  * Flakey: Used for testing only, simulates intermittent,
  24  * catastrophic device failure.
  25  */
  26 struct flakey_c {
  27         struct dm_dev *dev;
  28         unsigned long start_time;
  29         sector_t start;
  30         unsigned int up_interval;
  31         unsigned int down_interval;
  32         unsigned long flags;
  33         unsigned int corrupt_bio_byte;
  34         unsigned int corrupt_bio_rw;
  35         unsigned int corrupt_bio_value;
  36         blk_opf_t corrupt_bio_flags;
  37 };
  38
  39 enum feature_flag_bits {
  40         DROP_WRITES,
  41         ERROR_WRITES
  42 };
  43
  44 struct per_bio_data {
  45         bool bio_submitted;
  46 };
  47
  48 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
  49                           struct dm_target *ti)
  50 {
  51         int r;
  52         unsigned int argc;
  53         const char *arg_name;
  54
  55         static const struct dm_arg _args[] = {
  56                 {0, 6, "Invalid number of feature args"},
  57                 {1, UINT_MAX, "Invalid corrupt bio byte"},
  58                 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
  59                 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
  60         };
  61
  62         /* No feature arguments supplied. */
  63         if (!as->argc)
  64                 return 0;
  65
  66         r = dm_read_arg_group(_args, as, &argc, &ti->error);
  67         if (r)
  68                 return r;
  69
  70         while (argc) {
  71                 arg_name = dm_shift_arg(as);
  72                 argc--;
  73
  74                 if (!arg_name) {
  75                         ti->error = "Insufficient feature arguments";
  76                         return -EINVAL;
  77                 }
  78
  79                 /*
  80                  * drop_writes
  81                  */
  82                 if (!strcasecmp(arg_name, "drop_writes")) {
  83                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
  84                                 ti->error = "Feature drop_writes duplicated";
  85                                 return -EINVAL;
  86                         } else if (test_bit(ERROR_WRITES, &fc->flags)) {
  87                                 ti->error = "Feature drop_writes conflicts with feature error_writes";
  88                                 return -EINVAL;
  89                         }
  90
  91                         continue;
  92                 }
  93
  94                 /*
  95                  * error_writes
  96                  */
  97                 if (!strcasecmp(arg_name, "error_writes")) {
  98                         if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
  99                                 ti->error = "Feature error_writes duplicated";
 100                                 return -EINVAL;
 101
 102                         } else if (test_bit(DROP_WRITES, &fc->flags)) {
 103                                 ti->error = "Feature error_writes conflicts with feature drop_writes";
 104                                 return -EINVAL;
 105                         }
 106
 107                         continue;
 108                 }
 109
 110                 /*
 111                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
 112                  */
 113                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
 114                         if (!argc) {
 115                                 ti->error = "Feature corrupt_bio_byte requires parameters";
 116                                 return -EINVAL;
 117                         }
 118
 119                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
 120                         if (r)
 121                                 return r;
 122                         argc--;
 123
 124                         /*
 125                          * Direction r or w?
 126                          */
 127                         arg_name = dm_shift_arg(as);
 128                         if (!strcasecmp(arg_name, "w"))
 129                                 fc->corrupt_bio_rw = WRITE;
 130                         else if (!strcasecmp(arg_name, "r"))
 131                                 fc->corrupt_bio_rw = READ;
 132                         else {
 133                                 ti->error = "Invalid corrupt bio direction (r or w)";
 134                                 return -EINVAL;
 135                         }
 136                         argc--;
 137
 138                         /*
 139                          * Value of byte (0-255) to write in place of correct one.
 140                          */
 141                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
 142                         if (r)
 143                                 return r;
 144                         argc--;
 145
 146                         /*
 147                          * Only corrupt bios with these flags set.
 148                          */
 149                         BUILD_BUG_ON(sizeof(fc->corrupt_bio_flags) !=
 150                                      sizeof(unsigned int));
 151                         r = dm_read_arg(_args + 3, as,
 152                                 (__force unsigned int *)&fc->corrupt_bio_flags,
 153                                 &ti->error);
 154                         if (r)
 155                                 return r;
 156                         argc--;
 157
 158                         continue;
 159                 }
 160
 161                 ti->error = "Unrecognised flakey feature requested";
 162                 return -EINVAL;
 163         }
 164
 165         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 166                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 167                 return -EINVAL;
 168
 169         } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 170                 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 171                 return -EINVAL;
 172         }
 173
 174         return 0;
 175 }
 176
 177 /*
 178  * Construct a flakey mapping:
 179  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 180  *
 181  *   Feature args:
 182  *     [drop_writes]
 183  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 184  *
 185  *   Nth_byte starts from 1 for the first byte.
 186  *   Direction is r for READ or w for WRITE.
 187  *   bio_flags is ignored if 0.
 188  */
 189 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 190 {
 191         static const struct dm_arg _args[] = {
 192                 {0, UINT_MAX, "Invalid up interval"},
 193                 {0, UINT_MAX, "Invalid down interval"},
 194         };
 195
 196         int r;
 197         struct flakey_c *fc;
 198         unsigned long long tmpll;
 199         struct dm_arg_set as;
 200         const char *devname;
 201         char dummy;
 202
 203         as.argc = argc;
 204         as.argv = argv;
 205
 206         if (argc < 4) {
 207                 ti->error = "Invalid argument count";
 208                 return -EINVAL;
 209         }
 210
 211         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 212         if (!fc) {
 213                 ti->error = "Cannot allocate context";
 214                 return -ENOMEM;
 215         }
 216         fc->start_time = jiffies;
 217
 218         devname = dm_shift_arg(&as);
 219
 220         r = -EINVAL;
 221         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
 222                 ti->error = "Invalid device sector";
 223                 goto bad;
 224         }
 225         fc->start = tmpll;
 226
 227         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 228         if (r)
 229                 goto bad;
 230
 231         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 232         if (r)
 233                 goto bad;
 234
 235         if (!(fc->up_interval + fc->down_interval)) {
 236                 ti->error = "Total (up + down) interval is zero";
 237                 r = -EINVAL;
 238                 goto bad;
 239         }
 240
 241         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 242                 ti->error = "Interval overflow";
 243                 r = -EINVAL;
 244                 goto bad;
 245         }
 246
 247         r = parse_features(&as, fc, ti);
 248         if (r)
 249                 goto bad;
 250
 251         r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
 252         if (r) {
 253                 ti->error = "Device lookup failed";
 254                 goto bad;
 255         }
 256
 257         ti->num_flush_bios = 1;
 258         ti->num_discard_bios = 1;
 259         ti->per_io_data_size = sizeof(struct per_bio_data);
 260         ti->private = fc;
 261         return 0;
 262
 263 bad:
 264         kfree(fc);
 265         return r;
 266 }
 267
 268 static void flakey_dtr(struct dm_target *ti)
 269 {
 270         struct flakey_c *fc = ti->private;
 271
 272         dm_put_device(ti, fc->dev);
 273         kfree(fc);
 274 }
 275
 276 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 277 {
 278         struct flakey_c *fc = ti->private;
 279
 280         return fc->start + dm_target_offset(ti, bi_sector);
 281 }
 282
 283 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 284 {
 285         struct flakey_c *fc = ti->private;
 286
 287         bio_set_dev(bio, fc->dev->bdev);
 288         bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
 289 }
 290
 291 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 292 {
 293         unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
 294
 295         struct bvec_iter iter;
 296         struct bio_vec bvec;
 297
 298         if (!bio_has_data(bio))
 299                 return;
 300
 301         /*
 302          * Overwrite the Nth byte of the bio's data, on whichever page
 303          * it falls.
 304          */
 305         bio_for_each_segment(bvec, bio, iter) {
 306                 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
 307                         char *segment;
 308                         struct page *page = bio_iter_page(bio, iter);
 309                         if (unlikely(page == ZERO_PAGE(0)))
 310                                 break;
 311                         segment = bvec_kmap_local(&bvec);
 312                         segment[corrupt_bio_byte] = fc->corrupt_bio_value;
 313                         kunmap_local(segment);
 314                         DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 315                                 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
 316                                 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 317                                 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
 318                                 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 319                         break;
 320                 }
 321                 corrupt_bio_byte -= bio_iter_len(bio, iter);
 322         }
 323 }
 324
 325 static int flakey_map(struct dm_target *ti, struct bio *bio)
 326 {
 327         struct flakey_c *fc = ti->private;
 328         unsigned int elapsed;
 329         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 330
 331         pb->bio_submitted = false;
 332
 333         if (op_is_zone_mgmt(bio_op(bio)))
 334                 goto map_bio;
 335
 336         /* Are we alive ? */
 337         elapsed = (jiffies - fc->start_time) / HZ;
 338         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 339                 /*
 340                  * Flag this bio as submitted while down.
 341                  */
 342                 pb->bio_submitted = true;
 343
 344                 /*
 345                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
 346                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
 347                  */
 348                 if (bio_data_dir(bio) == READ) {
 349                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 350                             !test_bit(ERROR_WRITES, &fc->flags))
 351                                 return DM_MAPIO_KILL;
 352                         goto map_bio;
 353                 }
 354
 355                 /*
 356                  * Drop or error writes?
 357                  */
 358                 if (test_bit(DROP_WRITES, &fc->flags)) {
 359                         bio_endio(bio);
 360                         return DM_MAPIO_SUBMITTED;
 361                 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
 362                         bio_io_error(bio);
 363                         return DM_MAPIO_SUBMITTED;
 364                 }
 365
 366                 /*
 367                  * Corrupt matching writes.
 368                  */
 369                 if (fc->corrupt_bio_byte) {
 370                         if (fc->corrupt_bio_rw == WRITE) {
 371                                 if (all_corrupt_bio_flags_match(bio, fc))
 372                                         corrupt_bio_data(bio, fc);
 373                         }
 374                         goto map_bio;
 375                 }
 376
 377                 /*
 378                  * By default, error all I/O.
 379                  */
 380                 return DM_MAPIO_KILL;
 381         }
 382
 383 map_bio:
 384         flakey_map_bio(ti, bio);
 385
 386         return DM_MAPIO_REMAPPED;
 387 }
 388
 389 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 390                          blk_status_t *error)
 391 {
 392         struct flakey_c *fc = ti->private;
 393         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 394
 395         if (op_is_zone_mgmt(bio_op(bio)))
 396                 return DM_ENDIO_DONE;
 397
 398         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 399                 if (fc->corrupt_bio_byte) {
 400                         if ((fc->corrupt_bio_rw == READ) &&
 401                             all_corrupt_bio_flags_match(bio, fc)) {
 402                                 /*
 403                                  * Corrupt successful matching READs while in down state.
 404                                  */
 405                                 corrupt_bio_data(bio, fc);
 406                         }
 407                 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
 408                            !test_bit(ERROR_WRITES, &fc->flags)) {
 409                         /*
 410                          * Error read during the down_interval if drop_writes
 411                          * and error_writes were not configured.
 412                          */
 413                         *error = BLK_STS_IOERR;
 414                 }
 415         }
 416
 417         return DM_ENDIO_DONE;
 418 }
 419
 420 static void flakey_status(struct dm_target *ti, status_type_t type,
 421                           unsigned int status_flags, char *result, unsigned int maxlen)
 422 {
 423         unsigned int sz = 0;
 424         struct flakey_c *fc = ti->private;
 425         unsigned int drop_writes, error_writes;
 426
 427         switch (type) {
 428         case STATUSTYPE_INFO:
 429                 result[0] = '\0';
 430                 break;
 431
 432         case STATUSTYPE_TABLE:
 433                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 434                        (unsigned long long)fc->start, fc->up_interval,
 435                        fc->down_interval);
 436
 437                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 438                 error_writes = test_bit(ERROR_WRITES, &fc->flags);
 439                 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
 440
 441                 if (drop_writes)
 442                         DMEMIT("drop_writes ");
 443                 else if (error_writes)
 444                         DMEMIT("error_writes ");
 445
 446                 if (fc->corrupt_bio_byte)
 447                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 448                                fc->corrupt_bio_byte,
 449                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 450                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 451
 452                 break;
 453
 454         case STATUSTYPE_IMA:
 455                 result[0] = '\0';
 456                 break;
 457         }
 458 }
 459
 460 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 461 {
 462         struct flakey_c *fc = ti->private;
 463
 464         *bdev = fc->dev->bdev;
 465
 466         /*
 467          * Only pass ioctls through if the device sizes match exactly.
 468          */
 469         if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
 470                 return 1;
 471         return 0;
 472 }
 473
 474 #ifdef CONFIG_BLK_DEV_ZONED
 475 static int flakey_report_zones(struct dm_target *ti,
 476                 struct dm_report_zones_args *args, unsigned int nr_zones)
 477 {
 478         struct flakey_c *fc = ti->private;
 479
 480         return dm_report_zones(fc->dev->bdev, fc->start,
 481                                flakey_map_sector(ti, args->next_sector),
 482                                args, nr_zones);
 483 }
 484 #else
 485 #define flakey_report_zones NULL
 486 #endif
 487
 488 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 489 {
 490         struct flakey_c *fc = ti->private;
 491
 492         return fn(ti, fc->dev, fc->start, ti->len, data);
 493 }
 494
 495 static struct target_type flakey_target = {
 496         .name   = "flakey",
 497         .version = {1, 5, 0},
 498         .features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
 499         .report_zones = flakey_report_zones,
 500         .module = THIS_MODULE,
 501         .ctr    = flakey_ctr,
 502         .dtr    = flakey_dtr,
 503         .map    = flakey_map,
 504         .end_io = flakey_end_io,
 505         .status = flakey_status,
 506         .prepare_ioctl = flakey_prepare_ioctl,
 507         .iterate_devices = flakey_iterate_devices,
 508 };
 509
 510 static int __init dm_flakey_init(void)
 511 {
 512         int r = dm_register_target(&flakey_target);
 513
 514         if (r < 0)
 515                 DMERR("register failed %d", r);
 516
 517         return r;
 518 }
 519
 520 static void __exit dm_flakey_exit(void)
 521 {
 522         dm_unregister_target(&flakey_target);
 523 }
 524
 525 /* Module hooks */
 526 module_init(dm_flakey_init);
 527 module_exit(dm_flakey_exit);
 528
 529 MODULE_DESCRIPTION(DM_NAME " flakey target");
 530 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 531 MODULE_LICENSE("GPL");