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 *) verity_io_digest_end(io->v, io); 28 } 29 30 /* 31 * Return an interleaved offset for a byte in RS block. 32 */ 33 static inline u64 fec_interleave(struct dm_verity *v, u64 offset) 34 { 35 u32 mod; 36 37 mod = do_div(offset, v->fec->rsn); 38 return offset + mod * (v->fec->rounds << v->data_dev_block_bits); 39 } 40 41 /* 42 * Decode an RS block using Reed-Solomon. 43 */ 44 static int fec_decode_rs8(struct dm_verity *v, struct dm_verity_fec_io *fio, 45 u8 *data, u8 *fec, int neras) 46 { 47 int i; 48 uint16_t par[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN]; 49 50 for (i = 0; i < v->fec->roots; i++) 51 par[i] = fec[i]; 52 53 return decode_rs8(fio->rs, data, par, v->fec->rsn, NULL, neras, 54 fio->erasures, 0, NULL); 55 } 56 57 /* 58 * Read error-correcting codes for the requested RS block. Returns a pointer 59 * to the data block. Caller is responsible for releasing buf. 60 */ 61 static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index, 62 unsigned *offset, struct dm_buffer **buf) 63 { 64 u64 position, block, rem; 65 u8 *res; 66 67 position = (index + rsb) * v->fec->roots; 68 block = div64_u64_rem(position, v->fec->io_size, &rem); 69 *offset = (unsigned)rem; 70 71 res = dm_bufio_read(v->fec->bufio, block, buf); 72 if (IS_ERR(res)) { 73 DMERR("%s: FEC %llu: parity read failed (block %llu): %ld", 74 v->data_dev->name, (unsigned long long)rsb, 75 (unsigned long long)block, PTR_ERR(res)); 76 *buf = NULL; 77 } 78 79 return res; 80 } 81 82 /* Loop over each preallocated buffer slot. */ 83 #define fec_for_each_prealloc_buffer(__i) \ 84 for (__i = 0; __i < DM_VERITY_FEC_BUF_PREALLOC; __i++) 85 86 /* Loop over each extra buffer slot. */ 87 #define fec_for_each_extra_buffer(io, __i) \ 88 for (__i = DM_VERITY_FEC_BUF_PREALLOC; __i < DM_VERITY_FEC_BUF_MAX; __i++) 89 90 /* Loop over each allocated buffer. */ 91 #define fec_for_each_buffer(io, __i) \ 92 for (__i = 0; __i < (io)->nbufs; __i++) 93 94 /* Loop over each RS block in each allocated buffer. */ 95 #define fec_for_each_buffer_rs_block(io, __i, __j) \ 96 fec_for_each_buffer(io, __i) \ 97 for (__j = 0; __j < 1 << DM_VERITY_FEC_BUF_RS_BITS; __j++) 98 99 /* 100 * Return a pointer to the current RS block when called inside 101 * fec_for_each_buffer_rs_block. 102 */ 103 static inline u8 *fec_buffer_rs_block(struct dm_verity *v, 104 struct dm_verity_fec_io *fio, 105 unsigned i, unsigned j) 106 { 107 return &fio->bufs[i][j * v->fec->rsn]; 108 } 109 110 /* 111 * Return an index to the current RS block when called inside 112 * fec_for_each_buffer_rs_block. 113 */ 114 static inline unsigned fec_buffer_rs_index(unsigned i, unsigned j) 115 { 116 return (i << DM_VERITY_FEC_BUF_RS_BITS) + j; 117 } 118 119 /* 120 * Decode all RS blocks from buffers and copy corrected bytes into fio->output 121 * starting from block_offset. 122 */ 123 static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio, 124 u64 rsb, int byte_index, unsigned block_offset, 125 int neras) 126 { 127 int r, corrected = 0, res; 128 struct dm_buffer *buf; 129 unsigned n, i, offset; 130 u8 *par, *block; 131 132 par = fec_read_parity(v, rsb, block_offset, &offset, &buf); 133 if (IS_ERR(par)) 134 return PTR_ERR(par); 135 136 /* 137 * Decode the RS blocks we have in bufs. Each RS block results in 138 * one corrected target byte and consumes fec->roots parity bytes. 139 */ 140 fec_for_each_buffer_rs_block(fio, n, i) { 141 block = fec_buffer_rs_block(v, fio, n, i); 142 res = fec_decode_rs8(v, fio, block, &par[offset], neras); 143 if (res < 0) { 144 r = res; 145 goto error; 146 } 147 148 corrected += res; 149 fio->output[block_offset] = block[byte_index]; 150 151 block_offset++; 152 if (block_offset >= 1 << v->data_dev_block_bits) 153 goto done; 154 155 /* read the next block when we run out of parity bytes */ 156 offset += v->fec->roots; 157 if (offset >= v->fec->io_size) { 158 dm_bufio_release(buf); 159 160 par = fec_read_parity(v, rsb, block_offset, &offset, &buf); 161 if (IS_ERR(par)) 162 return PTR_ERR(par); 163 } 164 } 165 done: 166 r = corrected; 167 error: 168 dm_bufio_release(buf); 169 170 if (r < 0 && neras) 171 DMERR_LIMIT("%s: FEC %llu: failed to correct: %d", 172 v->data_dev->name, (unsigned long long)rsb, r); 173 else if (r > 0) 174 DMWARN_LIMIT("%s: FEC %llu: corrected %d errors", 175 v->data_dev->name, (unsigned long long)rsb, r); 176 177 return r; 178 } 179 180 /* 181 * Locate data block erasures using verity hashes. 182 */ 183 static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io, 184 u8 *want_digest, u8 *data) 185 { 186 if (unlikely(verity_hash(v, verity_io_hash_req(v, io), 187 data, 1 << v->data_dev_block_bits, 188 verity_io_real_digest(v, io)))) 189 return 0; 190 191 return memcmp(verity_io_real_digest(v, io), want_digest, 192 v->digest_size) != 0; 193 } 194 195 /* 196 * Read data blocks that are part of the RS block and deinterleave as much as 197 * fits into buffers. Check for erasure locations if @neras is non-NULL. 198 */ 199 static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, 200 u64 rsb, u64 target, unsigned block_offset, 201 int *neras) 202 { 203 bool is_zero; 204 int i, j, target_index = -1; 205 struct dm_buffer *buf; 206 struct dm_bufio_client *bufio; 207 struct dm_verity_fec_io *fio = fec_io(io); 208 u64 block, ileaved; 209 u8 *bbuf, *rs_block; 210 u8 want_digest[HASH_MAX_DIGESTSIZE]; 211 unsigned n, k; 212 213 if (neras) 214 *neras = 0; 215 216 if (WARN_ON(v->digest_size > sizeof(want_digest))) 217 return -EINVAL; 218 219 /* 220 * read each of the rsn data blocks that are part of the RS block, and 221 * interleave contents to available bufs 222 */ 223 for (i = 0; i < v->fec->rsn; i++) { 224 ileaved = fec_interleave(v, rsb * v->fec->rsn + i); 225 226 /* 227 * target is the data block we want to correct, target_index is 228 * the index of this block within the rsn RS blocks 229 */ 230 if (ileaved == target) 231 target_index = i; 232 233 block = ileaved >> v->data_dev_block_bits; 234 bufio = v->fec->data_bufio; 235 236 if (block >= v->data_blocks) { 237 block -= v->data_blocks; 238 239 /* 240 * blocks outside the area were assumed to contain 241 * zeros when encoding data was generated 242 */ 243 if (unlikely(block >= v->fec->hash_blocks)) 244 continue; 245 246 block += v->hash_start; 247 bufio = v->bufio; 248 } 249 250 bbuf = dm_bufio_read(bufio, block, &buf); 251 if (IS_ERR(bbuf)) { 252 DMWARN_LIMIT("%s: FEC %llu: read failed (%llu): %ld", 253 v->data_dev->name, 254 (unsigned long long)rsb, 255 (unsigned long long)block, PTR_ERR(bbuf)); 256 257 /* assume the block is corrupted */ 258 if (neras && *neras <= v->fec->roots) 259 fio->erasures[(*neras)++] = i; 260 261 continue; 262 } 263 264 /* locate erasures if the block is on the data device */ 265 if (bufio == v->fec->data_bufio && 266 verity_hash_for_block(v, io, block, want_digest, 267 &is_zero) == 0) { 268 /* skip known zero blocks entirely */ 269 if (is_zero) 270 goto done; 271 272 /* 273 * skip if we have already found the theoretical 274 * maximum number (i.e. fec->roots) of erasures 275 */ 276 if (neras && *neras <= v->fec->roots && 277 fec_is_erasure(v, io, want_digest, bbuf)) 278 fio->erasures[(*neras)++] = i; 279 } 280 281 /* 282 * deinterleave and copy the bytes that fit into bufs, 283 * starting from block_offset 284 */ 285 fec_for_each_buffer_rs_block(fio, n, j) { 286 k = fec_buffer_rs_index(n, j) + block_offset; 287 288 if (k >= 1 << v->data_dev_block_bits) 289 goto done; 290 291 rs_block = fec_buffer_rs_block(v, fio, n, j); 292 rs_block[i] = bbuf[k]; 293 } 294 done: 295 dm_bufio_release(buf); 296 } 297 298 return target_index; 299 } 300 301 /* 302 * Allocate RS control structure and FEC buffers from preallocated mempools, 303 * and attempt to allocate as many extra buffers as available. 304 */ 305 static int fec_alloc_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 306 { 307 unsigned n; 308 309 if (!fio->rs) 310 fio->rs = mempool_alloc(&v->fec->rs_pool, GFP_NOIO); 311 312 fec_for_each_prealloc_buffer(n) { 313 if (fio->bufs[n]) 314 continue; 315 316 fio->bufs[n] = mempool_alloc(&v->fec->prealloc_pool, GFP_NOWAIT); 317 if (unlikely(!fio->bufs[n])) { 318 DMERR("failed to allocate FEC buffer"); 319 return -ENOMEM; 320 } 321 } 322 323 /* try to allocate the maximum number of buffers */ 324 fec_for_each_extra_buffer(fio, n) { 325 if (fio->bufs[n]) 326 continue; 327 328 fio->bufs[n] = mempool_alloc(&v->fec->extra_pool, GFP_NOWAIT); 329 /* we can manage with even one buffer if necessary */ 330 if (unlikely(!fio->bufs[n])) 331 break; 332 } 333 fio->nbufs = n; 334 335 if (!fio->output) 336 fio->output = mempool_alloc(&v->fec->output_pool, GFP_NOIO); 337 338 return 0; 339 } 340 341 /* 342 * Initialize buffers and clear erasures. fec_read_bufs() assumes buffers are 343 * zeroed before deinterleaving. 344 */ 345 static void fec_init_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 346 { 347 unsigned n; 348 349 fec_for_each_buffer(fio, n) 350 memset(fio->bufs[n], 0, v->fec->rsn << DM_VERITY_FEC_BUF_RS_BITS); 351 352 memset(fio->erasures, 0, sizeof(fio->erasures)); 353 } 354 355 /* 356 * Decode all RS blocks in a single data block and return the target block 357 * (indicated by @offset) in fio->output. If @use_erasures is non-zero, uses 358 * hashes to locate erasures. 359 */ 360 static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io, 361 struct dm_verity_fec_io *fio, u64 rsb, u64 offset, 362 bool use_erasures) 363 { 364 int r, neras = 0; 365 unsigned pos; 366 367 r = fec_alloc_bufs(v, fio); 368 if (unlikely(r < 0)) 369 return r; 370 371 for (pos = 0; pos < 1 << v->data_dev_block_bits; ) { 372 fec_init_bufs(v, fio); 373 374 r = fec_read_bufs(v, io, rsb, offset, pos, 375 use_erasures ? &neras : NULL); 376 if (unlikely(r < 0)) 377 return r; 378 379 r = fec_decode_bufs(v, fio, rsb, r, pos, neras); 380 if (r < 0) 381 return r; 382 383 pos += fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS; 384 } 385 386 /* Always re-validate the corrected block against the expected hash */ 387 r = verity_hash(v, verity_io_hash_req(v, io), fio->output, 388 1 << v->data_dev_block_bits, 389 verity_io_real_digest(v, io)); 390 if (unlikely(r < 0)) 391 return r; 392 393 if (memcmp(verity_io_real_digest(v, io), verity_io_want_digest(v, io), 394 v->digest_size)) { 395 DMERR_LIMIT("%s: FEC %llu: failed to correct (%d erasures)", 396 v->data_dev->name, (unsigned long long)rsb, neras); 397 return -EILSEQ; 398 } 399 400 return 0; 401 } 402 403 static int fec_bv_copy(struct dm_verity *v, struct dm_verity_io *io, u8 *data, 404 size_t len) 405 { 406 struct dm_verity_fec_io *fio = fec_io(io); 407 408 memcpy(data, &fio->output[fio->output_pos], len); 409 fio->output_pos += len; 410 411 return 0; 412 } 413 414 /* 415 * Correct errors in a block. Copies corrected block to dest if non-NULL, 416 * otherwise to a bio_vec starting from iter. 417 */ 418 int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 419 enum verity_block_type type, sector_t block, u8 *dest, 420 struct bvec_iter *iter) 421 { 422 int r; 423 struct dm_verity_fec_io *fio = fec_io(io); 424 u64 offset, res, rsb; 425 426 if (!verity_fec_is_enabled(v)) 427 return -EOPNOTSUPP; 428 429 if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) { 430 DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name); 431 return -EIO; 432 } 433 434 fio->level++; 435 436 if (type == DM_VERITY_BLOCK_TYPE_METADATA) 437 block = block - v->hash_start + v->data_blocks; 438 439 /* 440 * For RS(M, N), the continuous FEC data is divided into blocks of N 441 * bytes. Since block size may not be divisible by N, the last block 442 * is zero padded when decoding. 443 * 444 * Each byte of the block is covered by a different RS(M, N) code, 445 * and each code is interleaved over N blocks to make it less likely 446 * that bursty corruption will leave us in unrecoverable state. 447 */ 448 449 offset = block << v->data_dev_block_bits; 450 res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits); 451 452 /* 453 * The base RS block we can feed to the interleaver to find out all 454 * blocks required for decoding. 455 */ 456 rsb = offset - res * (v->fec->rounds << v->data_dev_block_bits); 457 458 /* 459 * Locating erasures is slow, so attempt to recover the block without 460 * them first. Do a second attempt with erasures if the corruption is 461 * bad enough. 462 */ 463 r = fec_decode_rsb(v, io, fio, rsb, offset, false); 464 if (r < 0) { 465 r = fec_decode_rsb(v, io, fio, rsb, offset, true); 466 if (r < 0) 467 goto done; 468 } 469 470 if (dest) 471 memcpy(dest, fio->output, 1 << v->data_dev_block_bits); 472 else if (iter) { 473 fio->output_pos = 0; 474 r = verity_for_bv_block(v, io, iter, fec_bv_copy); 475 } 476 477 done: 478 fio->level--; 479 return r; 480 } 481 482 /* 483 * Clean up per-bio data. 484 */ 485 void verity_fec_finish_io(struct dm_verity_io *io) 486 { 487 unsigned n; 488 struct dm_verity_fec *f = io->v->fec; 489 struct dm_verity_fec_io *fio = fec_io(io); 490 491 if (!verity_fec_is_enabled(io->v)) 492 return; 493 494 mempool_free(fio->rs, &f->rs_pool); 495 496 fec_for_each_prealloc_buffer(n) 497 mempool_free(fio->bufs[n], &f->prealloc_pool); 498 499 fec_for_each_extra_buffer(fio, n) 500 mempool_free(fio->bufs[n], &f->extra_pool); 501 502 mempool_free(fio->output, &f->output_pool); 503 } 504 505 /* 506 * Initialize per-bio data. 507 */ 508 void verity_fec_init_io(struct dm_verity_io *io) 509 { 510 struct dm_verity_fec_io *fio = fec_io(io); 511 512 if (!verity_fec_is_enabled(io->v)) 513 return; 514 515 fio->rs = NULL; 516 memset(fio->bufs, 0, sizeof(fio->bufs)); 517 fio->nbufs = 0; 518 fio->output = NULL; 519 fio->level = 0; 520 } 521 522 /* 523 * Append feature arguments and values to the status table. 524 */ 525 unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz, 526 char *result, unsigned maxlen) 527 { 528 if (!verity_fec_is_enabled(v)) 529 return sz; 530 531 DMEMIT(" " DM_VERITY_OPT_FEC_DEV " %s " 532 DM_VERITY_OPT_FEC_BLOCKS " %llu " 533 DM_VERITY_OPT_FEC_START " %llu " 534 DM_VERITY_OPT_FEC_ROOTS " %d", 535 v->fec->dev->name, 536 (unsigned long long)v->fec->blocks, 537 (unsigned long long)v->fec->start, 538 v->fec->roots); 539 540 return sz; 541 } 542 543 void verity_fec_dtr(struct dm_verity *v) 544 { 545 struct dm_verity_fec *f = v->fec; 546 547 if (!verity_fec_is_enabled(v)) 548 goto out; 549 550 mempool_exit(&f->rs_pool); 551 mempool_exit(&f->prealloc_pool); 552 mempool_exit(&f->extra_pool); 553 mempool_exit(&f->output_pool); 554 kmem_cache_destroy(f->cache); 555 556 if (f->data_bufio) 557 dm_bufio_client_destroy(f->data_bufio); 558 if (f->bufio) 559 dm_bufio_client_destroy(f->bufio); 560 561 if (f->dev) 562 dm_put_device(v->ti, f->dev); 563 out: 564 kfree(f); 565 v->fec = NULL; 566 } 567 568 static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data) 569 { 570 struct dm_verity *v = (struct dm_verity *)pool_data; 571 572 return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask); 573 } 574 575 static void fec_rs_free(void *element, void *pool_data) 576 { 577 struct rs_control *rs = (struct rs_control *)element; 578 579 if (rs) 580 free_rs(rs); 581 } 582 583 bool verity_is_fec_opt_arg(const char *arg_name) 584 { 585 return (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV) || 586 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS) || 587 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_START) || 588 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)); 589 } 590 591 int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 592 unsigned *argc, const char *arg_name) 593 { 594 int r; 595 struct dm_target *ti = v->ti; 596 const char *arg_value; 597 unsigned long long num_ll; 598 unsigned char num_c; 599 char dummy; 600 601 if (!*argc) { 602 ti->error = "FEC feature arguments require a value"; 603 return -EINVAL; 604 } 605 606 arg_value = dm_shift_arg(as); 607 (*argc)--; 608 609 if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV)) { 610 r = dm_get_device(ti, arg_value, FMODE_READ, &v->fec->dev); 611 if (r) { 612 ti->error = "FEC device lookup failed"; 613 return r; 614 } 615 616 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS)) { 617 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 618 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 619 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 620 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 621 return -EINVAL; 622 } 623 v->fec->blocks = num_ll; 624 625 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_START)) { 626 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 627 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) >> 628 (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 629 ti->error = "Invalid " DM_VERITY_OPT_FEC_START; 630 return -EINVAL; 631 } 632 v->fec->start = num_ll; 633 634 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) { 635 if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c || 636 num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) || 637 num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) { 638 ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS; 639 return -EINVAL; 640 } 641 v->fec->roots = num_c; 642 643 } else { 644 ti->error = "Unrecognized verity FEC feature request"; 645 return -EINVAL; 646 } 647 648 return 0; 649 } 650 651 /* 652 * Allocate dm_verity_fec for v->fec. Must be called before verity_fec_ctr. 653 */ 654 int verity_fec_ctr_alloc(struct dm_verity *v) 655 { 656 struct dm_verity_fec *f; 657 658 f = kzalloc(sizeof(struct dm_verity_fec), GFP_KERNEL); 659 if (!f) { 660 v->ti->error = "Cannot allocate FEC structure"; 661 return -ENOMEM; 662 } 663 v->fec = f; 664 665 return 0; 666 } 667 668 /* 669 * Validate arguments and preallocate memory. Must be called after arguments 670 * have been parsed using verity_fec_parse_opt_args. 671 */ 672 int verity_fec_ctr(struct dm_verity *v) 673 { 674 struct dm_verity_fec *f = v->fec; 675 struct dm_target *ti = v->ti; 676 u64 hash_blocks, fec_blocks; 677 int ret; 678 679 if (!verity_fec_is_enabled(v)) { 680 verity_fec_dtr(v); 681 return 0; 682 } 683 684 /* 685 * FEC is computed over data blocks, possible metadata, and 686 * hash blocks. In other words, FEC covers total of fec_blocks 687 * blocks consisting of the following: 688 * 689 * data blocks | hash blocks | metadata (optional) 690 * 691 * We allow metadata after hash blocks to support a use case 692 * where all data is stored on the same device and FEC covers 693 * the entire area. 694 * 695 * If metadata is included, we require it to be available on the 696 * hash device after the hash blocks. 697 */ 698 699 hash_blocks = v->hash_blocks - v->hash_start; 700 701 /* 702 * Require matching block sizes for data and hash devices for 703 * simplicity. 704 */ 705 if (v->data_dev_block_bits != v->hash_dev_block_bits) { 706 ti->error = "Block sizes must match to use FEC"; 707 return -EINVAL; 708 } 709 710 if (!f->roots) { 711 ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS; 712 return -EINVAL; 713 } 714 f->rsn = DM_VERITY_FEC_RSM - f->roots; 715 716 if (!f->blocks) { 717 ti->error = "Missing " DM_VERITY_OPT_FEC_BLOCKS; 718 return -EINVAL; 719 } 720 721 f->rounds = f->blocks; 722 if (sector_div(f->rounds, f->rsn)) 723 f->rounds++; 724 725 /* 726 * Due to optional metadata, f->blocks can be larger than 727 * data_blocks and hash_blocks combined. 728 */ 729 if (f->blocks < v->data_blocks + hash_blocks || !f->rounds) { 730 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 731 return -EINVAL; 732 } 733 734 /* 735 * Metadata is accessed through the hash device, so we require 736 * it to be large enough. 737 */ 738 f->hash_blocks = f->blocks - v->data_blocks; 739 if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) { 740 ti->error = "Hash device is too small for " 741 DM_VERITY_OPT_FEC_BLOCKS; 742 return -E2BIG; 743 } 744 745 if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1)) 746 f->io_size = 1 << v->data_dev_block_bits; 747 else 748 f->io_size = v->fec->roots << SECTOR_SHIFT; 749 750 f->bufio = dm_bufio_client_create(f->dev->bdev, 751 f->io_size, 752 1, 0, NULL, NULL); 753 if (IS_ERR(f->bufio)) { 754 ti->error = "Cannot initialize FEC bufio client"; 755 return PTR_ERR(f->bufio); 756 } 757 758 dm_bufio_set_sector_offset(f->bufio, f->start << (v->data_dev_block_bits - SECTOR_SHIFT)); 759 760 fec_blocks = div64_u64(f->rounds * f->roots, v->fec->roots << SECTOR_SHIFT); 761 if (dm_bufio_get_device_size(f->bufio) < fec_blocks) { 762 ti->error = "FEC device is too small"; 763 return -E2BIG; 764 } 765 766 f->data_bufio = dm_bufio_client_create(v->data_dev->bdev, 767 1 << v->data_dev_block_bits, 768 1, 0, NULL, NULL); 769 if (IS_ERR(f->data_bufio)) { 770 ti->error = "Cannot initialize FEC data bufio client"; 771 return PTR_ERR(f->data_bufio); 772 } 773 774 if (dm_bufio_get_device_size(f->data_bufio) < v->data_blocks) { 775 ti->error = "Data device is too small"; 776 return -E2BIG; 777 } 778 779 /* Preallocate an rs_control structure for each worker thread */ 780 ret = mempool_init(&f->rs_pool, num_online_cpus(), fec_rs_alloc, 781 fec_rs_free, (void *) v); 782 if (ret) { 783 ti->error = "Cannot allocate RS pool"; 784 return ret; 785 } 786 787 f->cache = kmem_cache_create("dm_verity_fec_buffers", 788 f->rsn << DM_VERITY_FEC_BUF_RS_BITS, 789 0, 0, NULL); 790 if (!f->cache) { 791 ti->error = "Cannot create FEC buffer cache"; 792 return -ENOMEM; 793 } 794 795 /* Preallocate DM_VERITY_FEC_BUF_PREALLOC buffers for each thread */ 796 ret = mempool_init_slab_pool(&f->prealloc_pool, num_online_cpus() * 797 DM_VERITY_FEC_BUF_PREALLOC, 798 f->cache); 799 if (ret) { 800 ti->error = "Cannot allocate FEC buffer prealloc pool"; 801 return ret; 802 } 803 804 ret = mempool_init_slab_pool(&f->extra_pool, 0, f->cache); 805 if (ret) { 806 ti->error = "Cannot allocate FEC buffer extra pool"; 807 return ret; 808 } 809 810 /* Preallocate an output buffer for each thread */ 811 ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(), 812 1 << v->data_dev_block_bits); 813 if (ret) { 814 ti->error = "Cannot allocate FEC output pool"; 815 return ret; 816 } 817 818 /* Reserve space for our per-bio data */ 819 ti->per_io_data_size += sizeof(struct dm_verity_fec_io); 820 821 return 0; 822 } 823