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