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_rw & (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 };
  41
  42 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
  43                           struct dm_target *ti)
  44 {
  45         int r;
  46         unsigned argc;
  47         const char *arg_name;
  48
  49         static struct dm_arg _args[] = {
  50                 {0, 6, "Invalid number of feature args"},
  51                 {1, UINT_MAX, "Invalid corrupt bio byte"},
  52                 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
  53                 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
  54         };
  55
  56         /* No feature arguments supplied. */
  57         if (!as->argc)
  58                 return 0;
  59
  60         r = dm_read_arg_group(_args, as, &argc, &ti->error);
  61         if (r)
  62                 return r;
  63
  64         while (argc) {
  65                 arg_name = dm_shift_arg(as);
  66                 argc--;
  67
  68                 /*
  69                  * drop_writes
  70                  */
  71                 if (!strcasecmp(arg_name, "drop_writes")) {
  72                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
  73                                 ti->error = "Feature drop_writes duplicated";
  74                                 return -EINVAL;
  75                         }
  76
  77                         continue;
  78                 }
  79
  80                 /*
  81                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
  82                  */
  83                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
  84                         if (!argc) {
  85                                 ti->error = "Feature corrupt_bio_byte requires parameters";
  86                                 return -EINVAL;
  87                         }
  88
  89                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
  90                         if (r)
  91                                 return r;
  92                         argc--;
  93
  94                         /*
  95                          * Direction r or w?
  96                          */
  97                         arg_name = dm_shift_arg(as);
  98                         if (!strcasecmp(arg_name, "w"))
  99                                 fc->corrupt_bio_rw = WRITE;
 100                         else if (!strcasecmp(arg_name, "r"))
 101                                 fc->corrupt_bio_rw = READ;
 102                         else {
 103                                 ti->error = "Invalid corrupt bio direction (r or w)";
 104                                 return -EINVAL;
 105                         }
 106                         argc--;
 107
 108                         /*
 109                          * Value of byte (0-255) to write in place of correct one.
 110                          */
 111                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
 112                         if (r)
 113                                 return r;
 114                         argc--;
 115
 116                         /*
 117                          * Only corrupt bios with these flags set.
 118                          */
 119                         r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
 120                         if (r)
 121                                 return r;
 122                         argc--;
 123
 124                         continue;
 125                 }
 126
 127                 ti->error = "Unrecognised flakey feature requested";
 128                 return -EINVAL;
 129         }
 130
 131         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 132                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 133                 return -EINVAL;
 134         }
 135
 136         return 0;
 137 }
 138
 139 /*
 140  * Construct a flakey mapping:
 141  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 142  *
 143  *   Feature args:
 144  *     [drop_writes]
 145  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 146  *
 147  *   Nth_byte starts from 1 for the first byte.
 148  *   Direction is r for READ or w for WRITE.
 149  *   bio_flags is ignored if 0.
 150  */
 151 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 152 {
 153         static struct dm_arg _args[] = {
 154                 {0, UINT_MAX, "Invalid up interval"},
 155                 {0, UINT_MAX, "Invalid down interval"},
 156         };
 157
 158         int r;
 159         struct flakey_c *fc;
 160         unsigned long long tmpll;
 161         struct dm_arg_set as;
 162         const char *devname;
 163         char dummy;
 164
 165         as.argc = argc;
 166         as.argv = argv;
 167
 168         if (argc < 4) {
 169                 ti->error = "Invalid argument count";
 170                 return -EINVAL;
 171         }
 172
 173         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 174         if (!fc) {
 175                 ti->error = "Cannot allocate linear context";
 176                 return -ENOMEM;
 177         }
 178         fc->start_time = jiffies;
 179
 180         devname = dm_shift_arg(&as);
 181
 182         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
 183                 ti->error = "Invalid device sector";
 184                 goto bad;
 185         }
 186         fc->start = tmpll;
 187
 188         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 189         if (r)
 190                 goto bad;
 191
 192         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 193         if (r)
 194                 goto bad;
 195
 196         if (!(fc->up_interval + fc->down_interval)) {
 197                 ti->error = "Total (up + down) interval is zero";
 198                 goto bad;
 199         }
 200
 201         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 202                 ti->error = "Interval overflow";
 203                 goto bad;
 204         }
 205
 206         r = parse_features(&as, fc, ti);
 207         if (r)
 208                 goto bad;
 209
 210         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
 211                 ti->error = "Device lookup failed";
 212                 goto bad;
 213         }
 214
 215         ti->num_flush_requests = 1;
 216         ti->num_discard_requests = 1;
 217         ti->private = fc;
 218         return 0;
 219
 220 bad:
 221         kfree(fc);
 222         return -EINVAL;
 223 }
 224
 225 static void flakey_dtr(struct dm_target *ti)
 226 {
 227         struct flakey_c *fc = ti->private;
 228
 229         dm_put_device(ti, fc->dev);
 230         kfree(fc);
 231 }
 232
 233 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 234 {
 235         struct flakey_c *fc = ti->private;
 236
 237         return fc->start + dm_target_offset(ti, bi_sector);
 238 }
 239
 240 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 241 {
 242         struct flakey_c *fc = ti->private;
 243
 244         bio->bi_bdev = fc->dev->bdev;
 245         if (bio_sectors(bio))
 246                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
 247 }
 248
 249 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 250 {
 251         unsigned bio_bytes = bio_cur_bytes(bio);
 252         char *data = bio_data(bio);
 253
 254         /*
 255          * Overwrite the Nth byte of the data returned.
 256          */
 257         if (data && bio_bytes >= fc->corrupt_bio_byte) {
 258                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
 259
 260                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 261                         "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
 262                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 263                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
 264                         bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
 265         }
 266 }
 267
 268 static int flakey_map(struct dm_target *ti, struct bio *bio,
 269                       union map_info *map_context)
 270 {
 271         struct flakey_c *fc = ti->private;
 272         unsigned elapsed;
 273
 274         /* Are we alive ? */
 275         elapsed = (jiffies - fc->start_time) / HZ;
 276         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 277                 /*
 278                  * Flag this bio as submitted while down.
 279                  */
 280                 map_context->ll = 1;
 281
 282                 /*
 283                  * Map reads as normal.
 284                  */
 285                 if (bio_data_dir(bio) == READ)
 286                         goto map_bio;
 287
 288                 /*
 289                  * Drop writes?
 290                  */
 291                 if (test_bit(DROP_WRITES, &fc->flags)) {
 292                         bio_endio(bio, 0);
 293                         return DM_MAPIO_SUBMITTED;
 294                 }
 295
 296                 /*
 297                  * Corrupt matching writes.
 298                  */
 299                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
 300                         if (all_corrupt_bio_flags_match(bio, fc))
 301                                 corrupt_bio_data(bio, fc);
 302                         goto map_bio;
 303                 }
 304
 305                 /*
 306                  * By default, error all I/O.
 307                  */
 308                 return -EIO;
 309         }
 310
 311 map_bio:
 312         flakey_map_bio(ti, bio);
 313
 314         return DM_MAPIO_REMAPPED;
 315 }
 316
 317 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 318                          int error, union map_info *map_context)
 319 {
 320         struct flakey_c *fc = ti->private;
 321         unsigned bio_submitted_while_down = map_context->ll;
 322
 323         /*
 324          * Corrupt successful READs while in down state.
 325          * If flags were specified, only corrupt those that match.
 326          */
 327         if (fc->corrupt_bio_byte && !error && bio_submitted_while_down &&
 328             (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
 329             all_corrupt_bio_flags_match(bio, fc))
 330                 corrupt_bio_data(bio, fc);
 331
 332         return error;
 333 }
 334
 335 static int flakey_status(struct dm_target *ti, status_type_t type,
 336                          char *result, unsigned int maxlen)
 337 {
 338         unsigned sz = 0;
 339         struct flakey_c *fc = ti->private;
 340         unsigned drop_writes;
 341
 342         switch (type) {
 343         case STATUSTYPE_INFO:
 344                 result[0] = '\0';
 345                 break;
 346
 347         case STATUSTYPE_TABLE:
 348                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 349                        (unsigned long long)fc->start, fc->up_interval,
 350                        fc->down_interval);
 351
 352                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 353                 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
 354
 355                 if (drop_writes)
 356                         DMEMIT("drop_writes ");
 357
 358                 if (fc->corrupt_bio_byte)
 359                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 360                                fc->corrupt_bio_byte,
 361                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 362                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 363
 364                 break;
 365         }
 366         return 0;
 367 }
 368
 369 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 370 {
 371         struct flakey_c *fc = ti->private;
 372         struct dm_dev *dev = fc->dev;
 373         int r = 0;
 374
 375         /*
 376          * Only pass ioctls through if the device sizes match exactly.
 377          */
 378         if (fc->start ||
 379             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 380                 r = scsi_verify_blk_ioctl(NULL, cmd);
 381
 382         return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 383 }
 384
 385 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 386                         struct bio_vec *biovec, int max_size)
 387 {
 388         struct flakey_c *fc = ti->private;
 389         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
 390
 391         if (!q->merge_bvec_fn)
 392                 return max_size;
 393
 394         bvm->bi_bdev = fc->dev->bdev;
 395         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
 396
 397         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 398 }
 399
 400 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 401 {
 402         struct flakey_c *fc = ti->private;
 403
 404         return fn(ti, fc->dev, fc->start, ti->len, data);
 405 }
 406
 407 static struct target_type flakey_target = {
 408         .name   = "flakey",
 409         .version = {1, 2, 0},
 410         .module = THIS_MODULE,
 411         .ctr    = flakey_ctr,
 412         .dtr    = flakey_dtr,
 413         .map    = flakey_map,
 414         .end_io = flakey_end_io,
 415         .status = flakey_status,
 416         .ioctl  = flakey_ioctl,
 417         .merge  = flakey_merge,
 418         .iterate_devices = flakey_iterate_devices,
 419 };
 420
 421 static int __init dm_flakey_init(void)
 422 {
 423         int r = dm_register_target(&flakey_target);
 424
 425         if (r < 0)
 426                 DMERR("register failed %d", r);
 427
 428         return r;
 429 }
 430
 431 static void __exit dm_flakey_exit(void)
 432 {
 433         dm_unregister_target(&flakey_target);
 434 }
 435
 436 /* Module hooks */
 437 module_init(dm_flakey_init);
 438 module_exit(dm_flakey_exit);
 439
 440 MODULE_DESCRIPTION(DM_NAME " flakey target");
 441 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 442 MODULE_LICENSE("GPL");