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