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
 164         as.argc = argc;
 165         as.argv = argv;
 166
 167         if (argc < 4) {
 168                 ti->error = "Invalid argument count";
 169                 return -EINVAL;
 170         }
 171
 172         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 173         if (!fc) {
 174                 ti->error = "Cannot allocate linear context";
 175                 return -ENOMEM;
 176         }
 177         fc->start_time = jiffies;
 178
 179         devname = dm_shift_arg(&as);
 180
 181         if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
 182                 ti->error = "Invalid device sector";
 183                 goto bad;
 184         }
 185         fc->start = tmpll;
 186
 187         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 188         if (r)
 189                 goto bad;
 190
 191         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 192         if (r)
 193                 goto bad;
 194
 195         if (!(fc->up_interval + fc->down_interval)) {
 196                 ti->error = "Total (up + down) interval is zero";
 197                 goto bad;
 198         }
 199
 200         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 201                 ti->error = "Interval overflow";
 202                 goto bad;
 203         }
 204
 205         r = parse_features(&as, fc, ti);
 206         if (r)
 207                 goto bad;
 208
 209         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
 210                 ti->error = "Device lookup failed";
 211                 goto bad;
 212         }
 213
 214         ti->num_flush_requests = 1;
 215         ti->num_discard_requests = 1;
 216         ti->private = fc;
 217         return 0;
 218
 219 bad:
 220         kfree(fc);
 221         return -EINVAL;
 222 }
 223
 224 static void flakey_dtr(struct dm_target *ti)
 225 {
 226         struct flakey_c *fc = ti->private;
 227
 228         dm_put_device(ti, fc->dev);
 229         kfree(fc);
 230 }
 231
 232 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 233 {
 234         struct flakey_c *fc = ti->private;
 235
 236         return fc->start + dm_target_offset(ti, bi_sector);
 237 }
 238
 239 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 240 {
 241         struct flakey_c *fc = ti->private;
 242
 243         bio->bi_bdev = fc->dev->bdev;
 244         if (bio_sectors(bio))
 245                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
 246 }
 247
 248 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 249 {
 250         unsigned bio_bytes = bio_cur_bytes(bio);
 251         char *data = bio_data(bio);
 252
 253         /*
 254          * Overwrite the Nth byte of the data returned.
 255          */
 256         if (data && bio_bytes >= fc->corrupt_bio_byte) {
 257                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
 258
 259                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 260                         "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
 261                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 262                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
 263                         bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
 264         }
 265 }
 266
 267 static int flakey_map(struct dm_target *ti, struct bio *bio,
 268                       union map_info *map_context)
 269 {
 270         struct flakey_c *fc = ti->private;
 271         unsigned elapsed;
 272
 273         /* Are we alive ? */
 274         elapsed = (jiffies - fc->start_time) / HZ;
 275         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 276                 /*
 277                  * Flag this bio as submitted while down.
 278                  */
 279                 map_context->ll = 1;
 280
 281                 /*
 282                  * Map reads as normal.
 283                  */
 284                 if (bio_data_dir(bio) == READ)
 285                         goto map_bio;
 286
 287                 /*
 288                  * Drop writes?
 289                  */
 290                 if (test_bit(DROP_WRITES, &fc->flags)) {
 291                         bio_endio(bio, 0);
 292                         return DM_MAPIO_SUBMITTED;
 293                 }
 294
 295                 /*
 296                  * Corrupt matching writes.
 297                  */
 298                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
 299                         if (all_corrupt_bio_flags_match(bio, fc))
 300                                 corrupt_bio_data(bio, fc);
 301                         goto map_bio;
 302                 }
 303
 304                 /*
 305                  * By default, error all I/O.
 306                  */
 307                 return -EIO;
 308         }
 309
 310 map_bio:
 311         flakey_map_bio(ti, bio);
 312
 313         return DM_MAPIO_REMAPPED;
 314 }
 315
 316 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 317                          int error, union map_info *map_context)
 318 {
 319         struct flakey_c *fc = ti->private;
 320         unsigned bio_submitted_while_down = map_context->ll;
 321
 322         /*
 323          * Corrupt successful READs while in down state.
 324          * If flags were specified, only corrupt those that match.
 325          */
 326         if (!error && bio_submitted_while_down &&
 327             (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
 328             all_corrupt_bio_flags_match(bio, fc))
 329                 corrupt_bio_data(bio, fc);
 330
 331         return error;
 332 }
 333
 334 static int flakey_status(struct dm_target *ti, status_type_t type,
 335                          char *result, unsigned int maxlen)
 336 {
 337         unsigned sz = 0;
 338         struct flakey_c *fc = ti->private;
 339         unsigned drop_writes;
 340
 341         switch (type) {
 342         case STATUSTYPE_INFO:
 343                 result[0] = '\0';
 344                 break;
 345
 346         case STATUSTYPE_TABLE:
 347                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 348                        (unsigned long long)fc->start, fc->up_interval,
 349                        fc->down_interval);
 350
 351                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 352                 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
 353
 354                 if (drop_writes)
 355                         DMEMIT("drop_writes ");
 356
 357                 if (fc->corrupt_bio_byte)
 358                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 359                                fc->corrupt_bio_byte,
 360                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 361                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 362
 363                 break;
 364         }
 365         return 0;
 366 }
 367
 368 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 369 {
 370         struct flakey_c *fc = ti->private;
 371
 372         return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
 373 }
 374
 375 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 376                         struct bio_vec *biovec, int max_size)
 377 {
 378         struct flakey_c *fc = ti->private;
 379         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
 380
 381         if (!q->merge_bvec_fn)
 382                 return max_size;
 383
 384         bvm->bi_bdev = fc->dev->bdev;
 385         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
 386
 387         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 388 }
 389
 390 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 391 {
 392         struct flakey_c *fc = ti->private;
 393
 394         return fn(ti, fc->dev, fc->start, ti->len, data);
 395 }
 396
 397 static struct target_type flakey_target = {
 398         .name   = "flakey",
 399         .version = {1, 2, 0},
 400         .module = THIS_MODULE,
 401         .ctr    = flakey_ctr,
 402         .dtr    = flakey_dtr,
 403         .map    = flakey_map,
 404         .end_io = flakey_end_io,
 405         .status = flakey_status,
 406         .ioctl  = flakey_ioctl,
 407         .merge  = flakey_merge,
 408         .iterate_devices = flakey_iterate_devices,
 409 };
 410
 411 static int __init dm_flakey_init(void)
 412 {
 413         int r = dm_register_target(&flakey_target);
 414
 415         if (r < 0)
 416                 DMERR("register failed %d", r);
 417
 418         return r;
 419 }
 420
 421 static void __exit dm_flakey_exit(void)
 422 {
 423         dm_unregister_target(&flakey_target);
 424 }
 425
 426 /* Module hooks */
 427 module_init(dm_flakey_init);
 428 module_exit(dm_flakey_exit);
 429
 430 MODULE_DESCRIPTION(DM_NAME " flakey target");
 431 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 432 MODULE_LICENSE("GPL");