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