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