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 struct per_bio_data {
  43         bool bio_submitted;
  44 };
  45
  46 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
  47                           struct dm_target *ti)
  48 {
  49         int r;
  50         unsigned argc;
  51         const char *arg_name;
  52
  53         static struct dm_arg _args[] = {
  54                 {0, 6, "Invalid number of feature args"},
  55                 {1, UINT_MAX, "Invalid corrupt bio byte"},
  56                 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
  57                 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
  58         };
  59
  60         /* No feature arguments supplied. */
  61         if (!as->argc)
  62                 return 0;
  63
  64         r = dm_read_arg_group(_args, as, &argc, &ti->error);
  65         if (r)
  66                 return r;
  67
  68         while (argc) {
  69                 arg_name = dm_shift_arg(as);
  70                 argc--;
  71
  72                 /*
  73                  * drop_writes
  74                  */
  75                 if (!strcasecmp(arg_name, "drop_writes")) {
  76                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
  77                                 ti->error = "Feature drop_writes duplicated";
  78                                 return -EINVAL;
  79                         }
  80
  81                         continue;
  82                 }
  83
  84                 /*
  85                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
  86                  */
  87                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
  88                         if (!argc) {
  89                                 ti->error = "Feature corrupt_bio_byte requires parameters";
  90                                 return -EINVAL;
  91                         }
  92
  93                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
  94                         if (r)
  95                                 return r;
  96                         argc--;
  97
  98                         /*
  99                          * Direction r or w?
 100                          */
 101                         arg_name = dm_shift_arg(as);
 102                         if (!strcasecmp(arg_name, "w"))
 103                                 fc->corrupt_bio_rw = WRITE;
 104                         else if (!strcasecmp(arg_name, "r"))
 105                                 fc->corrupt_bio_rw = READ;
 106                         else {
 107                                 ti->error = "Invalid corrupt bio direction (r or w)";
 108                                 return -EINVAL;
 109                         }
 110                         argc--;
 111
 112                         /*
 113                          * Value of byte (0-255) to write in place of correct one.
 114                          */
 115                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
 116                         if (r)
 117                                 return r;
 118                         argc--;
 119
 120                         /*
 121                          * Only corrupt bios with these flags set.
 122                          */
 123                         r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
 124                         if (r)
 125                                 return r;
 126                         argc--;
 127
 128                         continue;
 129                 }
 130
 131                 ti->error = "Unrecognised flakey feature requested";
 132                 return -EINVAL;
 133         }
 134
 135         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
 136                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
 137                 return -EINVAL;
 138         }
 139
 140         return 0;
 141 }
 142
 143 /*
 144  * Construct a flakey mapping:
 145  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 146  *
 147  *   Feature args:
 148  *     [drop_writes]
 149  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 150  *
 151  *   Nth_byte starts from 1 for the first byte.
 152  *   Direction is r for READ or w for WRITE.
 153  *   bio_flags is ignored if 0.
 154  */
 155 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 156 {
 157         static struct dm_arg _args[] = {
 158                 {0, UINT_MAX, "Invalid up interval"},
 159                 {0, UINT_MAX, "Invalid down interval"},
 160         };
 161
 162         int r;
 163         struct flakey_c *fc;
 164         unsigned long long tmpll;
 165         struct dm_arg_set as;
 166         const char *devname;
 167         char dummy;
 168
 169         as.argc = argc;
 170         as.argv = argv;
 171
 172         if (argc < 4) {
 173                 ti->error = "Invalid argument count";
 174                 return -EINVAL;
 175         }
 176
 177         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 178         if (!fc) {
 179                 ti->error = "Cannot allocate linear context";
 180                 return -ENOMEM;
 181         }
 182         fc->start_time = jiffies;
 183
 184         devname = dm_shift_arg(&as);
 185
 186         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
 187                 ti->error = "Invalid device sector";
 188                 goto bad;
 189         }
 190         fc->start = tmpll;
 191
 192         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 193         if (r)
 194                 goto bad;
 195
 196         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 197         if (r)
 198                 goto bad;
 199
 200         if (!(fc->up_interval + fc->down_interval)) {
 201                 ti->error = "Total (up + down) interval is zero";
 202                 goto bad;
 203         }
 204
 205         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 206                 ti->error = "Interval overflow";
 207                 goto bad;
 208         }
 209
 210         r = parse_features(&as, fc, ti);
 211         if (r)
 212                 goto bad;
 213
 214         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
 215                 ti->error = "Device lookup failed";
 216                 goto bad;
 217         }
 218
 219         ti->num_flush_requests = 1;
 220         ti->num_discard_requests = 1;
 221         ti->per_bio_data_size = sizeof(struct per_bio_data);
 222         ti->private = fc;
 223         return 0;
 224
 225 bad:
 226         kfree(fc);
 227         return -EINVAL;
 228 }
 229
 230 static void flakey_dtr(struct dm_target *ti)
 231 {
 232         struct flakey_c *fc = ti->private;
 233
 234         dm_put_device(ti, fc->dev);
 235         kfree(fc);
 236 }
 237
 238 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 239 {
 240         struct flakey_c *fc = ti->private;
 241
 242         return fc->start + dm_target_offset(ti, bi_sector);
 243 }
 244
 245 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 246 {
 247         struct flakey_c *fc = ti->private;
 248
 249         bio->bi_bdev = fc->dev->bdev;
 250         if (bio_sectors(bio))
 251                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
 252 }
 253
 254 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
 255 {
 256         unsigned bio_bytes = bio_cur_bytes(bio);
 257         char *data = bio_data(bio);
 258
 259         /*
 260          * Overwrite the Nth byte of the data returned.
 261          */
 262         if (data && bio_bytes >= fc->corrupt_bio_byte) {
 263                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
 264
 265                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
 266                         "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
 267                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
 268                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
 269                         bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
 270         }
 271 }
 272
 273 static int flakey_map(struct dm_target *ti, struct bio *bio)
 274 {
 275         struct flakey_c *fc = ti->private;
 276         unsigned elapsed;
 277         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 278         pb->bio_submitted = false;
 279
 280         /* Are we alive ? */
 281         elapsed = (jiffies - fc->start_time) / HZ;
 282         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
 283                 /*
 284                  * Flag this bio as submitted while down.
 285                  */
 286                 pb->bio_submitted = true;
 287
 288                 /*
 289                  * Map reads as normal.
 290                  */
 291                 if (bio_data_dir(bio) == READ)
 292                         goto map_bio;
 293
 294                 /*
 295                  * Drop writes?
 296                  */
 297                 if (test_bit(DROP_WRITES, &fc->flags)) {
 298                         bio_endio(bio, 0);
 299                         return DM_MAPIO_SUBMITTED;
 300                 }
 301
 302                 /*
 303                  * Corrupt matching writes.
 304                  */
 305                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
 306                         if (all_corrupt_bio_flags_match(bio, fc))
 307                                 corrupt_bio_data(bio, fc);
 308                         goto map_bio;
 309                 }
 310
 311                 /*
 312                  * By default, error all I/O.
 313                  */
 314                 return -EIO;
 315         }
 316
 317 map_bio:
 318         flakey_map_bio(ti, bio);
 319
 320         return DM_MAPIO_REMAPPED;
 321 }
 322
 323 static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
 324 {
 325         struct flakey_c *fc = ti->private;
 326         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 327
 328         /*
 329          * Corrupt successful READs while in down state.
 330          * If flags were specified, only corrupt those that match.
 331          */
 332         if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
 333             (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
 334             all_corrupt_bio_flags_match(bio, fc))
 335                 corrupt_bio_data(bio, fc);
 336
 337         return error;
 338 }
 339
 340 static int flakey_status(struct dm_target *ti, status_type_t type,
 341                          unsigned status_flags, char *result, unsigned maxlen)
 342 {
 343         unsigned sz = 0;
 344         struct flakey_c *fc = ti->private;
 345         unsigned drop_writes;
 346
 347         switch (type) {
 348         case STATUSTYPE_INFO:
 349                 result[0] = '\0';
 350                 break;
 351
 352         case STATUSTYPE_TABLE:
 353                 DMEMIT("%s %llu %u %u ", fc->dev->name,
 354                        (unsigned long long)fc->start, fc->up_interval,
 355                        fc->down_interval);
 356
 357                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
 358                 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
 359
 360                 if (drop_writes)
 361                         DMEMIT("drop_writes ");
 362
 363                 if (fc->corrupt_bio_byte)
 364                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
 365                                fc->corrupt_bio_byte,
 366                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
 367                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
 368
 369                 break;
 370         }
 371         return 0;
 372 }
 373
 374 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 375 {
 376         struct flakey_c *fc = ti->private;
 377         struct dm_dev *dev = fc->dev;
 378         int r = 0;
 379
 380         /*
 381          * Only pass ioctls through if the device sizes match exactly.
 382          */
 383         if (fc->start ||
 384             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
 385                 r = scsi_verify_blk_ioctl(NULL, cmd);
 386
 387         return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 388 }
 389
 390 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 391                         struct bio_vec *biovec, int max_size)
 392 {
 393         struct flakey_c *fc = ti->private;
 394         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
 395
 396         if (!q->merge_bvec_fn)
 397                 return max_size;
 398
 399         bvm->bi_bdev = fc->dev->bdev;
 400         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
 401
 402         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 403 }
 404
 405 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 406 {
 407         struct flakey_c *fc = ti->private;
 408
 409         return fn(ti, fc->dev, fc->start, ti->len, data);
 410 }
 411
 412 static struct target_type flakey_target = {
 413         .name   = "flakey",
 414         .version = {1, 3, 0},
 415         .module = THIS_MODULE,
 416         .ctr    = flakey_ctr,
 417         .dtr    = flakey_dtr,
 418         .map    = flakey_map,
 419         .end_io = flakey_end_io,
 420         .status = flakey_status,
 421         .ioctl  = flakey_ioctl,
 422         .merge  = flakey_merge,
 423         .iterate_devices = flakey_iterate_devices,
 424 };
 425
 426 static int __init dm_flakey_init(void)
 427 {
 428         int r = dm_register_target(&flakey_target);
 429
 430         if (r < 0)
 431                 DMERR("register failed %d", r);
 432
 433         return r;
 434 }
 435
 436 static void __exit dm_flakey_exit(void)
 437 {
 438         dm_unregister_target(&flakey_target);
 439 }
 440
 441 /* Module hooks */
 442 module_init(dm_flakey_init);
 443 module_exit(dm_flakey_exit);
 444
 445 MODULE_DESCRIPTION(DM_NAME " flakey target");
 446 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 447 MODULE_LICENSE("GPL");