linux/drivers/md/dm-flakey.c
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   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 */
  25struct 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
  38enum feature_flag_bits {
  39        DROP_WRITES,
  40        ERROR_WRITES
  41};
  42
  43struct per_bio_data {
  44        bool bio_submitted;
  45};
  46
  47static 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 */
 184static 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
 258bad:
 259        kfree(fc);
 260        return r;
 261}
 262
 263static 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
 271static 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
 278static 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
 288static 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 = (page_address(bio_iter_page(bio, iter))
 305                                         + bio_iter_offset(bio, iter));
 306                        segment[corrupt_bio_byte] = fc->corrupt_bio_value;
 307                        DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 308                                "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
 309                                bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 310                                (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
 311                                (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
 312                        break;
 313                }
 314                corrupt_bio_byte -= bio_iter_len(bio, iter);
 315        }
 316}
 317
 318static int flakey_map(struct dm_target *ti, struct bio *bio)
 319{
 320        struct flakey_c *fc = ti->private;
 321        unsigned elapsed;
 322        struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 323        pb->bio_submitted = false;
 324
 325        if (op_is_zone_mgmt(bio_op(bio)))
 326                goto map_bio;
 327
 328        /* Are we alive ? */
 329        elapsed = (jiffies - fc->start_time) / HZ;
 330        if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 331                /*
 332                 * Flag this bio as submitted while down.
 333                 */
 334                pb->bio_submitted = true;
 335
 336                /*
 337                 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
 338                 * Otherwise, flakey_end_io() will decide if the reads should be modified.
 339                 */
 340                if (bio_data_dir(bio) == READ) {
 341                        if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 342                            !test_bit(ERROR_WRITES, &fc->flags))
 343                                return DM_MAPIO_KILL;
 344                        goto map_bio;
 345                }
 346
 347                /*
 348                 * Drop or error writes?
 349                 */
 350                if (test_bit(DROP_WRITES, &fc->flags)) {
 351                        bio_endio(bio);
 352                        return DM_MAPIO_SUBMITTED;
 353                }
 354                else if (test_bit(ERROR_WRITES, &fc->flags)) {
 355                        bio_io_error(bio);
 356                        return DM_MAPIO_SUBMITTED;
 357                }
 358
 359                /*
 360                 * Corrupt matching writes.
 361                 */
 362                if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
 363                        if (all_corrupt_bio_flags_match(bio, fc))
 364                                corrupt_bio_data(bio, fc);
 365                        goto map_bio;
 366                }
 367
 368                /*
 369                 * By default, error all I/O.
 370                 */
 371                return DM_MAPIO_KILL;
 372        }
 373
 374map_bio:
 375        flakey_map_bio(ti, bio);
 376
 377        return DM_MAPIO_REMAPPED;
 378}
 379
 380static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 381                         blk_status_t *error)
 382{
 383        struct flakey_c *fc = ti->private;
 384        struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 385
 386        if (op_is_zone_mgmt(bio_op(bio)))
 387                return DM_ENDIO_DONE;
 388
 389        if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 390                if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
 391                    all_corrupt_bio_flags_match(bio, fc)) {
 392                        /*
 393                         * Corrupt successful matching READs while in down state.
 394                         */
 395                        corrupt_bio_data(bio, fc);
 396
 397                } else if (!test_bit(DROP_WRITES, &fc->flags) &&
 398                           !test_bit(ERROR_WRITES, &fc->flags)) {
 399                        /*
 400                         * Error read during the down_interval if drop_writes
 401                         * and error_writes were not configured.
 402                         */
 403                        *error = BLK_STS_IOERR;
 404                }
 405        }
 406
 407        return DM_ENDIO_DONE;
 408}
 409
 410static void flakey_status(struct dm_target *ti, status_type_t type,
 411                          unsigned status_flags, char *result, unsigned maxlen)
 412{
 413        unsigned sz = 0;
 414        struct flakey_c *fc = ti->private;
 415        unsigned drop_writes, error_writes;
 416
 417        switch (type) {
 418        case STATUSTYPE_INFO:
 419                result[0] = '\0';
 420                break;
 421
 422        case STATUSTYPE_TABLE:
 423                DMEMIT("%s %llu %u %u ", fc->dev->name,
 424                       (unsigned long long)fc->start, fc->up_interval,
 425                       fc->down_interval);
 426
 427                drop_writes = test_bit(DROP_WRITES, &fc->flags);
 428                error_writes = test_bit(ERROR_WRITES, &fc->flags);
 429                DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
 430
 431                if (drop_writes)
 432                        DMEMIT("drop_writes ");
 433                else if (error_writes)
 434                        DMEMIT("error_writes ");
 435
 436                if (fc->corrupt_bio_byte)
 437                        DMEMIT("corrupt_bio_byte %u %c %u %u ",
 438                               fc->corrupt_bio_byte,
 439                               (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 440                               fc->corrupt_bio_value, fc->corrupt_bio_flags);
 441
 442                break;
 443        }
 444}
 445
 446static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 447{
 448        struct flakey_c *fc = ti->private;
 449
 450        *bdev = fc->dev->bdev;
 451
 452        /*
 453         * Only pass ioctls through if the device sizes match exactly.
 454         */
 455        if (fc->start ||
 456            ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
 457                return 1;
 458        return 0;
 459}
 460
 461#ifdef CONFIG_BLK_DEV_ZONED
 462static int flakey_report_zones(struct dm_target *ti,
 463                struct dm_report_zones_args *args, unsigned int nr_zones)
 464{
 465        struct flakey_c *fc = ti->private;
 466        sector_t sector = flakey_map_sector(ti, args->next_sector);
 467
 468        args->start = fc->start;
 469        return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
 470                                   dm_report_zones_cb, args);
 471}
 472#endif
 473
 474static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 475{
 476        struct flakey_c *fc = ti->private;
 477
 478        return fn(ti, fc->dev, fc->start, ti->len, data);
 479}
 480
 481static struct target_type flakey_target = {
 482        .name   = "flakey",
 483        .version = {1, 5, 0},
 484#ifdef CONFIG_BLK_DEV_ZONED
 485        .features = DM_TARGET_ZONED_HM,
 486        .report_zones = flakey_report_zones,
 487#endif
 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
 498static 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
 508static void __exit dm_flakey_exit(void)
 509{
 510        dm_unregister_target(&flakey_target);
 511}
 512
 513/* Module hooks */
 514module_init(dm_flakey_init);
 515module_exit(dm_flakey_exit);
 516
 517MODULE_DESCRIPTION(DM_NAME " flakey target");
 518MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 519MODULE_LICENSE("GPL");
 520