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 const 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 if (!arg_name) { 74 ti->error = "Insufficient feature arguments"; 75 return -EINVAL; 76 } 77 78 /* 79 * drop_writes 80 */ 81 if (!strcasecmp(arg_name, "drop_writes")) { 82 if (test_and_set_bit(DROP_WRITES, &fc->flags)) { 83 ti->error = "Feature drop_writes duplicated"; 84 return -EINVAL; 85 } else if (test_bit(ERROR_WRITES, &fc->flags)) { 86 ti->error = "Feature drop_writes conflicts with feature error_writes"; 87 return -EINVAL; 88 } 89 90 continue; 91 } 92 93 /* 94 * error_writes 95 */ 96 if (!strcasecmp(arg_name, "error_writes")) { 97 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) { 98 ti->error = "Feature error_writes duplicated"; 99 return -EINVAL; 100 101 } else if (test_bit(DROP_WRITES, &fc->flags)) { 102 ti->error = "Feature error_writes conflicts with feature drop_writes"; 103 return -EINVAL; 104 } 105 106 continue; 107 } 108 109 /* 110 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags> 111 */ 112 if (!strcasecmp(arg_name, "corrupt_bio_byte")) { 113 if (!argc) { 114 ti->error = "Feature corrupt_bio_byte requires parameters"; 115 return -EINVAL; 116 } 117 118 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error); 119 if (r) 120 return r; 121 argc--; 122 123 /* 124 * Direction r or w? 125 */ 126 arg_name = dm_shift_arg(as); 127 if (!strcasecmp(arg_name, "w")) 128 fc->corrupt_bio_rw = WRITE; 129 else if (!strcasecmp(arg_name, "r")) 130 fc->corrupt_bio_rw = READ; 131 else { 132 ti->error = "Invalid corrupt bio direction (r or w)"; 133 return -EINVAL; 134 } 135 argc--; 136 137 /* 138 * Value of byte (0-255) to write in place of correct one. 139 */ 140 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error); 141 if (r) 142 return r; 143 argc--; 144 145 /* 146 * Only corrupt bios with these flags set. 147 */ 148 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error); 149 if (r) 150 return r; 151 argc--; 152 153 continue; 154 } 155 156 ti->error = "Unrecognised flakey feature requested"; 157 return -EINVAL; 158 } 159 160 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) { 161 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set"; 162 return -EINVAL; 163 164 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) { 165 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set"; 166 return -EINVAL; 167 } 168 169 return 0; 170 } 171 172 /* 173 * Construct a flakey mapping: 174 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*] 175 * 176 * Feature args: 177 * [drop_writes] 178 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>] 179 * 180 * Nth_byte starts from 1 for the first byte. 181 * Direction is r for READ or w for WRITE. 182 * bio_flags is ignored if 0. 183 */ 184 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv) 185 { 186 static const struct dm_arg _args[] = { 187 {0, UINT_MAX, "Invalid up interval"}, 188 {0, UINT_MAX, "Invalid down interval"}, 189 }; 190 191 int r; 192 struct flakey_c *fc; 193 unsigned long long tmpll; 194 struct dm_arg_set as; 195 const char *devname; 196 char dummy; 197 198 as.argc = argc; 199 as.argv = argv; 200 201 if (argc < 4) { 202 ti->error = "Invalid argument count"; 203 return -EINVAL; 204 } 205 206 fc = kzalloc(sizeof(*fc), GFP_KERNEL); 207 if (!fc) { 208 ti->error = "Cannot allocate context"; 209 return -ENOMEM; 210 } 211 fc->start_time = jiffies; 212 213 devname = dm_shift_arg(&as); 214 215 r = -EINVAL; 216 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) { 217 ti->error = "Invalid device sector"; 218 goto bad; 219 } 220 fc->start = tmpll; 221 222 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error); 223 if (r) 224 goto bad; 225 226 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error); 227 if (r) 228 goto bad; 229 230 if (!(fc->up_interval + fc->down_interval)) { 231 ti->error = "Total (up + down) interval is zero"; 232 r = -EINVAL; 233 goto bad; 234 } 235 236 if (fc->up_interval + fc->down_interval < fc->up_interval) { 237 ti->error = "Interval overflow"; 238 r = -EINVAL; 239 goto bad; 240 } 241 242 r = parse_features(&as, fc, ti); 243 if (r) 244 goto bad; 245 246 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev); 247 if (r) { 248 ti->error = "Device lookup failed"; 249 goto bad; 250 } 251 252 ti->num_flush_bios = 1; 253 ti->num_discard_bios = 1; 254 ti->per_io_data_size = sizeof(struct per_bio_data); 255 ti->private = fc; 256 return 0; 257 258 bad: 259 kfree(fc); 260 return r; 261 } 262 263 static void flakey_dtr(struct dm_target *ti) 264 { 265 struct flakey_c *fc = ti->private; 266 267 dm_put_device(ti, fc->dev); 268 kfree(fc); 269 } 270 271 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector) 272 { 273 struct flakey_c *fc = ti->private; 274 275 return fc->start + dm_target_offset(ti, bi_sector); 276 } 277 278 static void flakey_map_bio(struct dm_target *ti, struct bio *bio) 279 { 280 struct flakey_c *fc = ti->private; 281 282 bio_set_dev(bio, fc->dev->bdev); 283 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) 284 bio->bi_iter.bi_sector = 285 flakey_map_sector(ti, bio->bi_iter.bi_sector); 286 } 287 288 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc) 289 { 290 unsigned bio_bytes = bio_cur_bytes(bio); 291 char *data = bio_data(bio); 292 293 /* 294 * Overwrite the Nth byte of the data returned. 295 */ 296 if (data && bio_bytes >= fc->corrupt_bio_byte) { 297 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value; 298 299 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u " 300 "(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n", 301 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte, 302 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf, 303 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes); 304 } 305 } 306 307 static int flakey_map(struct dm_target *ti, struct bio *bio) 308 { 309 struct flakey_c *fc = ti->private; 310 unsigned elapsed; 311 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 312 pb->bio_submitted = false; 313 314 /* Do not fail reset zone */ 315 if (bio_op(bio) == REQ_OP_ZONE_RESET) 316 goto map_bio; 317 318 /* We need to remap reported zones, so remember the BIO iter */ 319 if (bio_op(bio) == REQ_OP_ZONE_REPORT) 320 goto map_bio; 321 322 /* Are we alive ? */ 323 elapsed = (jiffies - fc->start_time) / HZ; 324 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) { 325 /* 326 * Flag this bio as submitted while down. 327 */ 328 pb->bio_submitted = true; 329 330 /* 331 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set. 332 * Otherwise, flakey_end_io() will decide if the reads should be modified. 333 */ 334 if (bio_data_dir(bio) == READ) { 335 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) && 336 !test_bit(ERROR_WRITES, &fc->flags)) 337 return DM_MAPIO_KILL; 338 goto map_bio; 339 } 340 341 /* 342 * Drop or error writes? 343 */ 344 if (test_bit(DROP_WRITES, &fc->flags)) { 345 bio_endio(bio); 346 return DM_MAPIO_SUBMITTED; 347 } 348 else if (test_bit(ERROR_WRITES, &fc->flags)) { 349 bio_io_error(bio); 350 return DM_MAPIO_SUBMITTED; 351 } 352 353 /* 354 * Corrupt matching writes. 355 */ 356 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) { 357 if (all_corrupt_bio_flags_match(bio, fc)) 358 corrupt_bio_data(bio, fc); 359 goto map_bio; 360 } 361 362 /* 363 * By default, error all I/O. 364 */ 365 return DM_MAPIO_KILL; 366 } 367 368 map_bio: 369 flakey_map_bio(ti, bio); 370 371 return DM_MAPIO_REMAPPED; 372 } 373 374 static int flakey_end_io(struct dm_target *ti, struct bio *bio, 375 blk_status_t *error) 376 { 377 struct flakey_c *fc = ti->private; 378 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 379 380 if (bio_op(bio) == REQ_OP_ZONE_RESET) 381 return DM_ENDIO_DONE; 382 383 if (bio_op(bio) == REQ_OP_ZONE_REPORT) { 384 dm_remap_zone_report(ti, bio, fc->start); 385 return DM_ENDIO_DONE; 386 } 387 388 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) { 389 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) && 390 all_corrupt_bio_flags_match(bio, fc)) { 391 /* 392 * Corrupt successful matching READs while in down state. 393 */ 394 corrupt_bio_data(bio, fc); 395 396 } else if (!test_bit(DROP_WRITES, &fc->flags) && 397 !test_bit(ERROR_WRITES, &fc->flags)) { 398 /* 399 * Error read during the down_interval if drop_writes 400 * and error_writes were not configured. 401 */ 402 *error = BLK_STS_IOERR; 403 } 404 } 405 406 return DM_ENDIO_DONE; 407 } 408 409 static void flakey_status(struct dm_target *ti, status_type_t type, 410 unsigned status_flags, char *result, unsigned maxlen) 411 { 412 unsigned sz = 0; 413 struct flakey_c *fc = ti->private; 414 unsigned drop_writes, error_writes; 415 416 switch (type) { 417 case STATUSTYPE_INFO: 418 result[0] = '\0'; 419 break; 420 421 case STATUSTYPE_TABLE: 422 DMEMIT("%s %llu %u %u ", fc->dev->name, 423 (unsigned long long)fc->start, fc->up_interval, 424 fc->down_interval); 425 426 drop_writes = test_bit(DROP_WRITES, &fc->flags); 427 error_writes = test_bit(ERROR_WRITES, &fc->flags); 428 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5); 429 430 if (drop_writes) 431 DMEMIT("drop_writes "); 432 else if (error_writes) 433 DMEMIT("error_writes "); 434 435 if (fc->corrupt_bio_byte) 436 DMEMIT("corrupt_bio_byte %u %c %u %u ", 437 fc->corrupt_bio_byte, 438 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r', 439 fc->corrupt_bio_value, fc->corrupt_bio_flags); 440 441 break; 442 } 443 } 444 445 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 446 { 447 struct flakey_c *fc = ti->private; 448 449 *bdev = fc->dev->bdev; 450 451 /* 452 * Only pass ioctls through if the device sizes match exactly. 453 */ 454 if (fc->start || 455 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT) 456 return 1; 457 return 0; 458 } 459 460 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) 461 { 462 struct flakey_c *fc = ti->private; 463 464 return fn(ti, fc->dev, fc->start, ti->len, data); 465 } 466 467 static struct target_type flakey_target = { 468 .name = "flakey", 469 .version = {1, 5, 0}, 470 .features = DM_TARGET_ZONED_HM, 471 .module = THIS_MODULE, 472 .ctr = flakey_ctr, 473 .dtr = flakey_dtr, 474 .map = flakey_map, 475 .end_io = flakey_end_io, 476 .status = flakey_status, 477 .prepare_ioctl = flakey_prepare_ioctl, 478 .iterate_devices = flakey_iterate_devices, 479 }; 480 481 static int __init dm_flakey_init(void) 482 { 483 int r = dm_register_target(&flakey_target); 484 485 if (r < 0) 486 DMERR("register failed %d", r); 487 488 return r; 489 } 490 491 static void __exit dm_flakey_exit(void) 492 { 493 dm_unregister_target(&flakey_target); 494 } 495 496 /* Module hooks */ 497 module_init(dm_flakey_init); 498 module_exit(dm_flakey_exit); 499 500 MODULE_DESCRIPTION(DM_NAME " flakey target"); 501 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); 502 MODULE_LICENSE("GPL"); 503