1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2015 Google, Inc. 4 * 5 * Author: Sami Tolvanen <samitolvanen@google.com> 6 */ 7 8 #include "dm-verity-fec.h" 9 #include <linux/math64.h> 10 11 #define DM_MSG_PREFIX "verity-fec" 12 13 /* 14 * If error correction has been configured, returns true. 15 */ 16 bool verity_fec_is_enabled(struct dm_verity *v) 17 { 18 return v->fec && v->fec->dev; 19 } 20 21 /* 22 * Return a pointer to dm_verity_fec_io after dm_verity_io and its variable 23 * length fields. 24 */ 25 static inline struct dm_verity_fec_io *fec_io(struct dm_verity_io *io) 26 { 27 return (struct dm_verity_fec_io *) 28 ((char *)io + io->v->ti->per_io_data_size - sizeof(struct dm_verity_fec_io)); 29 } 30 31 /* 32 * Return an interleaved offset for a byte in RS block. 33 */ 34 static inline u64 fec_interleave(struct dm_verity *v, u64 offset) 35 { 36 u32 mod; 37 38 mod = do_div(offset, v->fec->rsn); 39 return offset + mod * (v->fec->rounds << v->data_dev_block_bits); 40 } 41 42 /* 43 * Decode an RS block using Reed-Solomon. 44 */ 45 static int fec_decode_rs8(struct dm_verity *v, struct dm_verity_fec_io *fio, 46 u8 *data, u8 *fec, int neras) 47 { 48 int i; 49 uint16_t par[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN]; 50 51 for (i = 0; i < v->fec->roots; i++) 52 par[i] = fec[i]; 53 54 return decode_rs8(fio->rs, data, par, v->fec->rsn, NULL, neras, 55 fio->erasures, 0, NULL); 56 } 57 58 /* 59 * Read error-correcting codes for the requested RS block. Returns a pointer 60 * to the data block. Caller is responsible for releasing buf. 61 */ 62 static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index, 63 unsigned int *offset, struct dm_buffer **buf, 64 unsigned short ioprio) 65 { 66 u64 position, block, rem; 67 u8 *res; 68 69 position = (index + rsb) * v->fec->roots; 70 block = div64_u64_rem(position, v->fec->io_size, &rem); 71 *offset = (unsigned int)rem; 72 73 res = dm_bufio_read_with_ioprio(v->fec->bufio, block, buf, ioprio); 74 if (IS_ERR(res)) { 75 DMERR("%s: FEC %llu: parity read failed (block %llu): %ld", 76 v->data_dev->name, (unsigned long long)rsb, 77 (unsigned long long)block, PTR_ERR(res)); 78 *buf = NULL; 79 } 80 81 return res; 82 } 83 84 /* Loop over each preallocated buffer slot. */ 85 #define fec_for_each_prealloc_buffer(__i) \ 86 for (__i = 0; __i < DM_VERITY_FEC_BUF_PREALLOC; __i++) 87 88 /* Loop over each extra buffer slot. */ 89 #define fec_for_each_extra_buffer(io, __i) \ 90 for (__i = DM_VERITY_FEC_BUF_PREALLOC; __i < DM_VERITY_FEC_BUF_MAX; __i++) 91 92 /* Loop over each allocated buffer. */ 93 #define fec_for_each_buffer(io, __i) \ 94 for (__i = 0; __i < (io)->nbufs; __i++) 95 96 /* Loop over each RS block in each allocated buffer. */ 97 #define fec_for_each_buffer_rs_block(io, __i, __j) \ 98 fec_for_each_buffer(io, __i) \ 99 for (__j = 0; __j < 1 << DM_VERITY_FEC_BUF_RS_BITS; __j++) 100 101 /* 102 * Return a pointer to the current RS block when called inside 103 * fec_for_each_buffer_rs_block. 104 */ 105 static inline u8 *fec_buffer_rs_block(struct dm_verity *v, 106 struct dm_verity_fec_io *fio, 107 unsigned int i, unsigned int j) 108 { 109 return &fio->bufs[i][j * v->fec->rsn]; 110 } 111 112 /* 113 * Return an index to the current RS block when called inside 114 * fec_for_each_buffer_rs_block. 115 */ 116 static inline unsigned int fec_buffer_rs_index(unsigned int i, unsigned int j) 117 { 118 return (i << DM_VERITY_FEC_BUF_RS_BITS) + j; 119 } 120 121 /* 122 * Decode all RS blocks from buffers and copy corrected bytes into fio->output 123 * starting from block_offset. 124 */ 125 static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 126 struct dm_verity_fec_io *fio, u64 rsb, int byte_index, 127 unsigned int block_offset, int neras) 128 { 129 int r, corrected = 0, res; 130 struct dm_buffer *buf; 131 unsigned int n, i, offset; 132 u8 *par, *block; 133 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 134 135 par = fec_read_parity(v, rsb, block_offset, &offset, &buf, bio_prio(bio)); 136 if (IS_ERR(par)) 137 return PTR_ERR(par); 138 139 /* 140 * Decode the RS blocks we have in bufs. Each RS block results in 141 * one corrected target byte and consumes fec->roots parity bytes. 142 */ 143 fec_for_each_buffer_rs_block(fio, n, i) { 144 block = fec_buffer_rs_block(v, fio, n, i); 145 res = fec_decode_rs8(v, fio, block, &par[offset], neras); 146 if (res < 0) { 147 r = res; 148 goto error; 149 } 150 151 corrected += res; 152 fio->output[block_offset] = block[byte_index]; 153 154 block_offset++; 155 if (block_offset >= 1 << v->data_dev_block_bits) 156 goto done; 157 158 /* read the next block when we run out of parity bytes */ 159 offset += v->fec->roots; 160 if (offset >= v->fec->io_size) { 161 dm_bufio_release(buf); 162 163 par = fec_read_parity(v, rsb, block_offset, &offset, &buf, bio_prio(bio)); 164 if (IS_ERR(par)) 165 return PTR_ERR(par); 166 } 167 } 168 done: 169 r = corrected; 170 error: 171 dm_bufio_release(buf); 172 173 if (r < 0 && neras) 174 DMERR_LIMIT("%s: FEC %llu: failed to correct: %d", 175 v->data_dev->name, (unsigned long long)rsb, r); 176 else if (r > 0) 177 DMWARN_LIMIT("%s: FEC %llu: corrected %d errors", 178 v->data_dev->name, (unsigned long long)rsb, r); 179 180 return r; 181 } 182 183 /* 184 * Locate data block erasures using verity hashes. 185 */ 186 static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io, 187 u8 *want_digest, u8 *data) 188 { 189 if (unlikely(verity_hash(v, io, data, 1 << v->data_dev_block_bits, 190 verity_io_real_digest(v, io), true))) 191 return 0; 192 193 return memcmp(verity_io_real_digest(v, io), want_digest, 194 v->digest_size) != 0; 195 } 196 197 /* 198 * Read data blocks that are part of the RS block and deinterleave as much as 199 * fits into buffers. Check for erasure locations if @neras is non-NULL. 200 */ 201 static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, 202 u64 rsb, u64 target, unsigned int block_offset, 203 int *neras) 204 { 205 bool is_zero; 206 int i, j, target_index = -1; 207 struct dm_buffer *buf; 208 struct dm_bufio_client *bufio; 209 struct dm_verity_fec_io *fio = fec_io(io); 210 u64 block, ileaved; 211 u8 *bbuf, *rs_block; 212 u8 want_digest[HASH_MAX_DIGESTSIZE]; 213 unsigned int n, k; 214 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 215 216 if (neras) 217 *neras = 0; 218 219 if (WARN_ON(v->digest_size > sizeof(want_digest))) 220 return -EINVAL; 221 222 /* 223 * read each of the rsn data blocks that are part of the RS block, and 224 * interleave contents to available bufs 225 */ 226 for (i = 0; i < v->fec->rsn; i++) { 227 ileaved = fec_interleave(v, rsb * v->fec->rsn + i); 228 229 /* 230 * target is the data block we want to correct, target_index is 231 * the index of this block within the rsn RS blocks 232 */ 233 if (ileaved == target) 234 target_index = i; 235 236 block = ileaved >> v->data_dev_block_bits; 237 bufio = v->fec->data_bufio; 238 239 if (block >= v->data_blocks) { 240 block -= v->data_blocks; 241 242 /* 243 * blocks outside the area were assumed to contain 244 * zeros when encoding data was generated 245 */ 246 if (unlikely(block >= v->fec->hash_blocks)) 247 continue; 248 249 block += v->hash_start; 250 bufio = v->bufio; 251 } 252 253 bbuf = dm_bufio_read_with_ioprio(bufio, block, &buf, bio_prio(bio)); 254 if (IS_ERR(bbuf)) { 255 DMWARN_LIMIT("%s: FEC %llu: read failed (%llu): %ld", 256 v->data_dev->name, 257 (unsigned long long)rsb, 258 (unsigned long long)block, PTR_ERR(bbuf)); 259 260 /* assume the block is corrupted */ 261 if (neras && *neras <= v->fec->roots) 262 fio->erasures[(*neras)++] = i; 263 264 continue; 265 } 266 267 /* locate erasures if the block is on the data device */ 268 if (bufio == v->fec->data_bufio && 269 verity_hash_for_block(v, io, block, want_digest, 270 &is_zero) == 0) { 271 /* skip known zero blocks entirely */ 272 if (is_zero) 273 goto done; 274 275 /* 276 * skip if we have already found the theoretical 277 * maximum number (i.e. fec->roots) of erasures 278 */ 279 if (neras && *neras <= v->fec->roots && 280 fec_is_erasure(v, io, want_digest, bbuf)) 281 fio->erasures[(*neras)++] = i; 282 } 283 284 /* 285 * deinterleave and copy the bytes that fit into bufs, 286 * starting from block_offset 287 */ 288 fec_for_each_buffer_rs_block(fio, n, j) { 289 k = fec_buffer_rs_index(n, j) + block_offset; 290 291 if (k >= 1 << v->data_dev_block_bits) 292 goto done; 293 294 rs_block = fec_buffer_rs_block(v, fio, n, j); 295 rs_block[i] = bbuf[k]; 296 } 297 done: 298 dm_bufio_release(buf); 299 } 300 301 return target_index; 302 } 303 304 /* 305 * Allocate RS control structure and FEC buffers from preallocated mempools, 306 * and attempt to allocate as many extra buffers as available. 307 */ 308 static int fec_alloc_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 309 { 310 unsigned int n; 311 312 if (!fio->rs) 313 fio->rs = mempool_alloc(&v->fec->rs_pool, GFP_NOIO); 314 315 fec_for_each_prealloc_buffer(n) { 316 if (fio->bufs[n]) 317 continue; 318 319 fio->bufs[n] = mempool_alloc(&v->fec->prealloc_pool, GFP_NOWAIT); 320 if (unlikely(!fio->bufs[n])) { 321 DMERR("failed to allocate FEC buffer"); 322 return -ENOMEM; 323 } 324 } 325 326 /* try to allocate the maximum number of buffers */ 327 fec_for_each_extra_buffer(fio, n) { 328 if (fio->bufs[n]) 329 continue; 330 331 fio->bufs[n] = mempool_alloc(&v->fec->extra_pool, GFP_NOWAIT); 332 /* we can manage with even one buffer if necessary */ 333 if (unlikely(!fio->bufs[n])) 334 break; 335 } 336 fio->nbufs = n; 337 338 if (!fio->output) 339 fio->output = mempool_alloc(&v->fec->output_pool, GFP_NOIO); 340 341 return 0; 342 } 343 344 /* 345 * Initialize buffers and clear erasures. fec_read_bufs() assumes buffers are 346 * zeroed before deinterleaving. 347 */ 348 static void fec_init_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 349 { 350 unsigned int n; 351 352 fec_for_each_buffer(fio, n) 353 memset(fio->bufs[n], 0, v->fec->rsn << DM_VERITY_FEC_BUF_RS_BITS); 354 355 memset(fio->erasures, 0, sizeof(fio->erasures)); 356 } 357 358 /* 359 * Decode all RS blocks in a single data block and return the target block 360 * (indicated by @offset) in fio->output. If @use_erasures is non-zero, uses 361 * hashes to locate erasures. 362 */ 363 static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io, 364 struct dm_verity_fec_io *fio, u64 rsb, u64 offset, 365 bool use_erasures) 366 { 367 int r, neras = 0; 368 unsigned int pos; 369 370 r = fec_alloc_bufs(v, fio); 371 if (unlikely(r < 0)) 372 return r; 373 374 for (pos = 0; pos < 1 << v->data_dev_block_bits; ) { 375 fec_init_bufs(v, fio); 376 377 r = fec_read_bufs(v, io, rsb, offset, pos, 378 use_erasures ? &neras : NULL); 379 if (unlikely(r < 0)) 380 return r; 381 382 r = fec_decode_bufs(v, io, fio, rsb, r, pos, neras); 383 if (r < 0) 384 return r; 385 386 pos += fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS; 387 } 388 389 /* Always re-validate the corrected block against the expected hash */ 390 r = verity_hash(v, io, fio->output, 1 << v->data_dev_block_bits, 391 verity_io_real_digest(v, io), true); 392 if (unlikely(r < 0)) 393 return r; 394 395 if (memcmp(verity_io_real_digest(v, io), verity_io_want_digest(v, io), 396 v->digest_size)) { 397 DMERR_LIMIT("%s: FEC %llu: failed to correct (%d erasures)", 398 v->data_dev->name, (unsigned long long)rsb, neras); 399 return -EILSEQ; 400 } 401 402 return 0; 403 } 404 405 /* Correct errors in a block. Copies corrected block to dest. */ 406 int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 407 enum verity_block_type type, sector_t block, u8 *dest) 408 { 409 int r; 410 struct dm_verity_fec_io *fio = fec_io(io); 411 u64 offset, res, rsb; 412 413 if (!verity_fec_is_enabled(v)) 414 return -EOPNOTSUPP; 415 416 if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) { 417 DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name); 418 return -EIO; 419 } 420 421 fio->level++; 422 423 if (type == DM_VERITY_BLOCK_TYPE_METADATA) 424 block = block - v->hash_start + v->data_blocks; 425 426 /* 427 * For RS(M, N), the continuous FEC data is divided into blocks of N 428 * bytes. Since block size may not be divisible by N, the last block 429 * is zero padded when decoding. 430 * 431 * Each byte of the block is covered by a different RS(M, N) code, 432 * and each code is interleaved over N blocks to make it less likely 433 * that bursty corruption will leave us in unrecoverable state. 434 */ 435 436 offset = block << v->data_dev_block_bits; 437 res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits); 438 439 /* 440 * The base RS block we can feed to the interleaver to find out all 441 * blocks required for decoding. 442 */ 443 rsb = offset - res * (v->fec->rounds << v->data_dev_block_bits); 444 445 /* 446 * Locating erasures is slow, so attempt to recover the block without 447 * them first. Do a second attempt with erasures if the corruption is 448 * bad enough. 449 */ 450 r = fec_decode_rsb(v, io, fio, rsb, offset, false); 451 if (r < 0) { 452 r = fec_decode_rsb(v, io, fio, rsb, offset, true); 453 if (r < 0) 454 goto done; 455 } 456 457 memcpy(dest, fio->output, 1 << v->data_dev_block_bits); 458 459 done: 460 fio->level--; 461 return r; 462 } 463 464 /* 465 * Clean up per-bio data. 466 */ 467 void verity_fec_finish_io(struct dm_verity_io *io) 468 { 469 unsigned int n; 470 struct dm_verity_fec *f = io->v->fec; 471 struct dm_verity_fec_io *fio = fec_io(io); 472 473 if (!verity_fec_is_enabled(io->v)) 474 return; 475 476 mempool_free(fio->rs, &f->rs_pool); 477 478 fec_for_each_prealloc_buffer(n) 479 mempool_free(fio->bufs[n], &f->prealloc_pool); 480 481 fec_for_each_extra_buffer(fio, n) 482 mempool_free(fio->bufs[n], &f->extra_pool); 483 484 mempool_free(fio->output, &f->output_pool); 485 } 486 487 /* 488 * Initialize per-bio data. 489 */ 490 void verity_fec_init_io(struct dm_verity_io *io) 491 { 492 struct dm_verity_fec_io *fio = fec_io(io); 493 494 if (!verity_fec_is_enabled(io->v)) 495 return; 496 497 fio->rs = NULL; 498 memset(fio->bufs, 0, sizeof(fio->bufs)); 499 fio->nbufs = 0; 500 fio->output = NULL; 501 fio->level = 0; 502 } 503 504 /* 505 * Append feature arguments and values to the status table. 506 */ 507 unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, 508 char *result, unsigned int maxlen) 509 { 510 if (!verity_fec_is_enabled(v)) 511 return sz; 512 513 DMEMIT(" " DM_VERITY_OPT_FEC_DEV " %s " 514 DM_VERITY_OPT_FEC_BLOCKS " %llu " 515 DM_VERITY_OPT_FEC_START " %llu " 516 DM_VERITY_OPT_FEC_ROOTS " %d", 517 v->fec->dev->name, 518 (unsigned long long)v->fec->blocks, 519 (unsigned long long)v->fec->start, 520 v->fec->roots); 521 522 return sz; 523 } 524 525 void verity_fec_dtr(struct dm_verity *v) 526 { 527 struct dm_verity_fec *f = v->fec; 528 529 if (!verity_fec_is_enabled(v)) 530 goto out; 531 532 mempool_exit(&f->rs_pool); 533 mempool_exit(&f->prealloc_pool); 534 mempool_exit(&f->extra_pool); 535 mempool_exit(&f->output_pool); 536 kmem_cache_destroy(f->cache); 537 538 if (f->data_bufio) 539 dm_bufio_client_destroy(f->data_bufio); 540 if (f->bufio) 541 dm_bufio_client_destroy(f->bufio); 542 543 if (f->dev) 544 dm_put_device(v->ti, f->dev); 545 out: 546 kfree(f); 547 v->fec = NULL; 548 } 549 550 static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data) 551 { 552 struct dm_verity *v = pool_data; 553 554 return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask); 555 } 556 557 static void fec_rs_free(void *element, void *pool_data) 558 { 559 struct rs_control *rs = element; 560 561 if (rs) 562 free_rs(rs); 563 } 564 565 bool verity_is_fec_opt_arg(const char *arg_name) 566 { 567 return (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV) || 568 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS) || 569 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_START) || 570 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)); 571 } 572 573 int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 574 unsigned int *argc, const char *arg_name) 575 { 576 int r; 577 struct dm_target *ti = v->ti; 578 const char *arg_value; 579 unsigned long long num_ll; 580 unsigned char num_c; 581 char dummy; 582 583 if (!*argc) { 584 ti->error = "FEC feature arguments require a value"; 585 return -EINVAL; 586 } 587 588 arg_value = dm_shift_arg(as); 589 (*argc)--; 590 591 if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV)) { 592 r = dm_get_device(ti, arg_value, BLK_OPEN_READ, &v->fec->dev); 593 if (r) { 594 ti->error = "FEC device lookup failed"; 595 return r; 596 } 597 598 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS)) { 599 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 600 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 601 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 602 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 603 return -EINVAL; 604 } 605 v->fec->blocks = num_ll; 606 607 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_START)) { 608 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 609 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) >> 610 (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 611 ti->error = "Invalid " DM_VERITY_OPT_FEC_START; 612 return -EINVAL; 613 } 614 v->fec->start = num_ll; 615 616 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) { 617 if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c || 618 num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) || 619 num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) { 620 ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS; 621 return -EINVAL; 622 } 623 v->fec->roots = num_c; 624 625 } else { 626 ti->error = "Unrecognized verity FEC feature request"; 627 return -EINVAL; 628 } 629 630 return 0; 631 } 632 633 /* 634 * Allocate dm_verity_fec for v->fec. Must be called before verity_fec_ctr. 635 */ 636 int verity_fec_ctr_alloc(struct dm_verity *v) 637 { 638 struct dm_verity_fec *f; 639 640 f = kzalloc(sizeof(struct dm_verity_fec), GFP_KERNEL); 641 if (!f) { 642 v->ti->error = "Cannot allocate FEC structure"; 643 return -ENOMEM; 644 } 645 v->fec = f; 646 647 return 0; 648 } 649 650 /* 651 * Validate arguments and preallocate memory. Must be called after arguments 652 * have been parsed using verity_fec_parse_opt_args. 653 */ 654 int verity_fec_ctr(struct dm_verity *v) 655 { 656 struct dm_verity_fec *f = v->fec; 657 struct dm_target *ti = v->ti; 658 u64 hash_blocks, fec_blocks; 659 int ret; 660 661 if (!verity_fec_is_enabled(v)) { 662 verity_fec_dtr(v); 663 return 0; 664 } 665 666 /* 667 * FEC is computed over data blocks, possible metadata, and 668 * hash blocks. In other words, FEC covers total of fec_blocks 669 * blocks consisting of the following: 670 * 671 * data blocks | hash blocks | metadata (optional) 672 * 673 * We allow metadata after hash blocks to support a use case 674 * where all data is stored on the same device and FEC covers 675 * the entire area. 676 * 677 * If metadata is included, we require it to be available on the 678 * hash device after the hash blocks. 679 */ 680 681 hash_blocks = v->hash_blocks - v->hash_start; 682 683 /* 684 * Require matching block sizes for data and hash devices for 685 * simplicity. 686 */ 687 if (v->data_dev_block_bits != v->hash_dev_block_bits) { 688 ti->error = "Block sizes must match to use FEC"; 689 return -EINVAL; 690 } 691 692 if (!f->roots) { 693 ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS; 694 return -EINVAL; 695 } 696 f->rsn = DM_VERITY_FEC_RSM - f->roots; 697 698 if (!f->blocks) { 699 ti->error = "Missing " DM_VERITY_OPT_FEC_BLOCKS; 700 return -EINVAL; 701 } 702 703 f->rounds = f->blocks; 704 if (sector_div(f->rounds, f->rsn)) 705 f->rounds++; 706 707 /* 708 * Due to optional metadata, f->blocks can be larger than 709 * data_blocks and hash_blocks combined. 710 */ 711 if (f->blocks < v->data_blocks + hash_blocks || !f->rounds) { 712 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 713 return -EINVAL; 714 } 715 716 /* 717 * Metadata is accessed through the hash device, so we require 718 * it to be large enough. 719 */ 720 f->hash_blocks = f->blocks - v->data_blocks; 721 if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) { 722 ti->error = "Hash device is too small for " 723 DM_VERITY_OPT_FEC_BLOCKS; 724 return -E2BIG; 725 } 726 727 if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1)) 728 f->io_size = 1 << v->data_dev_block_bits; 729 else 730 f->io_size = v->fec->roots << SECTOR_SHIFT; 731 732 f->bufio = dm_bufio_client_create(f->dev->bdev, 733 f->io_size, 734 1, 0, NULL, NULL, 0); 735 if (IS_ERR(f->bufio)) { 736 ti->error = "Cannot initialize FEC bufio client"; 737 return PTR_ERR(f->bufio); 738 } 739 740 dm_bufio_set_sector_offset(f->bufio, f->start << (v->data_dev_block_bits - SECTOR_SHIFT)); 741 742 fec_blocks = div64_u64(f->rounds * f->roots, v->fec->roots << SECTOR_SHIFT); 743 if (dm_bufio_get_device_size(f->bufio) < fec_blocks) { 744 ti->error = "FEC device is too small"; 745 return -E2BIG; 746 } 747 748 f->data_bufio = dm_bufio_client_create(v->data_dev->bdev, 749 1 << v->data_dev_block_bits, 750 1, 0, NULL, NULL, 0); 751 if (IS_ERR(f->data_bufio)) { 752 ti->error = "Cannot initialize FEC data bufio client"; 753 return PTR_ERR(f->data_bufio); 754 } 755 756 if (dm_bufio_get_device_size(f->data_bufio) < v->data_blocks) { 757 ti->error = "Data device is too small"; 758 return -E2BIG; 759 } 760 761 /* Preallocate an rs_control structure for each worker thread */ 762 ret = mempool_init(&f->rs_pool, num_online_cpus(), fec_rs_alloc, 763 fec_rs_free, (void *) v); 764 if (ret) { 765 ti->error = "Cannot allocate RS pool"; 766 return ret; 767 } 768 769 f->cache = kmem_cache_create("dm_verity_fec_buffers", 770 f->rsn << DM_VERITY_FEC_BUF_RS_BITS, 771 0, 0, NULL); 772 if (!f->cache) { 773 ti->error = "Cannot create FEC buffer cache"; 774 return -ENOMEM; 775 } 776 777 /* Preallocate DM_VERITY_FEC_BUF_PREALLOC buffers for each thread */ 778 ret = mempool_init_slab_pool(&f->prealloc_pool, num_online_cpus() * 779 DM_VERITY_FEC_BUF_PREALLOC, 780 f->cache); 781 if (ret) { 782 ti->error = "Cannot allocate FEC buffer prealloc pool"; 783 return ret; 784 } 785 786 ret = mempool_init_slab_pool(&f->extra_pool, 0, f->cache); 787 if (ret) { 788 ti->error = "Cannot allocate FEC buffer extra pool"; 789 return ret; 790 } 791 792 /* Preallocate an output buffer for each thread */ 793 ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(), 794 1 << v->data_dev_block_bits); 795 if (ret) { 796 ti->error = "Cannot allocate FEC output pool"; 797 return ret; 798 } 799 800 /* Reserve space for our per-bio data */ 801 ti->per_io_data_size += sizeof(struct dm_verity_fec_io); 802 803 return 0; 804 } 805