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 */ 16bool 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 */ 25static 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 */ 34static 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 */ 45static 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 */ 62static 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 */ 105static 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 */ 116static 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 */ 125static 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 } 168done: 169 r = corrected; 170error: 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 */ 186static 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, verity_io_hash_req(v, io), 190 data, 1 << v->data_dev_block_bits, 191 verity_io_real_digest(v, io), true))) 192 return 0; 193 194 return memcmp(verity_io_real_digest(v, io), want_digest, 195 v->digest_size) != 0; 196} 197 198/* 199 * Read data blocks that are part of the RS block and deinterleave as much as 200 * fits into buffers. Check for erasure locations if @neras is non-NULL. 201 */ 202static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, 203 u64 rsb, u64 target, unsigned int block_offset, 204 int *neras) 205{ 206 bool is_zero; 207 int i, j, target_index = -1; 208 struct dm_buffer *buf; 209 struct dm_bufio_client *bufio; 210 struct dm_verity_fec_io *fio = fec_io(io); 211 u64 block, ileaved; 212 u8 *bbuf, *rs_block; 213 u8 want_digest[HASH_MAX_DIGESTSIZE]; 214 unsigned int n, k; 215 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 216 217 if (neras) 218 *neras = 0; 219 220 if (WARN_ON(v->digest_size > sizeof(want_digest))) 221 return -EINVAL; 222 223 /* 224 * read each of the rsn data blocks that are part of the RS block, and 225 * interleave contents to available bufs 226 */ 227 for (i = 0; i < v->fec->rsn; i++) { 228 ileaved = fec_interleave(v, rsb * v->fec->rsn + i); 229 230 /* 231 * target is the data block we want to correct, target_index is 232 * the index of this block within the rsn RS blocks 233 */ 234 if (ileaved == target) 235 target_index = i; 236 237 block = ileaved >> v->data_dev_block_bits; 238 bufio = v->fec->data_bufio; 239 240 if (block >= v->data_blocks) { 241 block -= v->data_blocks; 242 243 /* 244 * blocks outside the area were assumed to contain 245 * zeros when encoding data was generated 246 */ 247 if (unlikely(block >= v->fec->hash_blocks)) 248 continue; 249 250 block += v->hash_start; 251 bufio = v->bufio; 252 } 253 254 bbuf = dm_bufio_read_with_ioprio(bufio, block, &buf, bio_prio(bio)); 255 if (IS_ERR(bbuf)) { 256 DMWARN_LIMIT("%s: FEC %llu: read failed (%llu): %ld", 257 v->data_dev->name, 258 (unsigned long long)rsb, 259 (unsigned long long)block, PTR_ERR(bbuf)); 260 261 /* assume the block is corrupted */ 262 if (neras && *neras <= v->fec->roots) 263 fio->erasures[(*neras)++] = i; 264 265 continue; 266 } 267 268 /* locate erasures if the block is on the data device */ 269 if (bufio == v->fec->data_bufio && 270 verity_hash_for_block(v, io, block, want_digest, 271 &is_zero) == 0) { 272 /* skip known zero blocks entirely */ 273 if (is_zero) 274 goto done; 275 276 /* 277 * skip if we have already found the theoretical 278 * maximum number (i.e. fec->roots) of erasures 279 */ 280 if (neras && *neras <= v->fec->roots && 281 fec_is_erasure(v, io, want_digest, bbuf)) 282 fio->erasures[(*neras)++] = i; 283 } 284 285 /* 286 * deinterleave and copy the bytes that fit into bufs, 287 * starting from block_offset 288 */ 289 fec_for_each_buffer_rs_block(fio, n, j) { 290 k = fec_buffer_rs_index(n, j) + block_offset; 291 292 if (k >= 1 << v->data_dev_block_bits) 293 goto done; 294 295 rs_block = fec_buffer_rs_block(v, fio, n, j); 296 rs_block[i] = bbuf[k]; 297 } 298done: 299 dm_bufio_release(buf); 300 } 301 302 return target_index; 303} 304 305/* 306 * Allocate RS control structure and FEC buffers from preallocated mempools, 307 * and attempt to allocate as many extra buffers as available. 308 */ 309static int fec_alloc_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 310{ 311 unsigned int n; 312 313 if (!fio->rs) 314 fio->rs = mempool_alloc(&v->fec->rs_pool, GFP_NOIO); 315 316 fec_for_each_prealloc_buffer(n) { 317 if (fio->bufs[n]) 318 continue; 319 320 fio->bufs[n] = mempool_alloc(&v->fec->prealloc_pool, GFP_NOWAIT); 321 if (unlikely(!fio->bufs[n])) { 322 DMERR("failed to allocate FEC buffer"); 323 return -ENOMEM; 324 } 325 } 326 327 /* try to allocate the maximum number of buffers */ 328 fec_for_each_extra_buffer(fio, n) { 329 if (fio->bufs[n]) 330 continue; 331 332 fio->bufs[n] = mempool_alloc(&v->fec->extra_pool, GFP_NOWAIT); 333 /* we can manage with even one buffer if necessary */ 334 if (unlikely(!fio->bufs[n])) 335 break; 336 } 337 fio->nbufs = n; 338 339 if (!fio->output) 340 fio->output = mempool_alloc(&v->fec->output_pool, GFP_NOIO); 341 342 return 0; 343} 344 345/* 346 * Initialize buffers and clear erasures. fec_read_bufs() assumes buffers are 347 * zeroed before deinterleaving. 348 */ 349static void fec_init_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio) 350{ 351 unsigned int n; 352 353 fec_for_each_buffer(fio, n) 354 memset(fio->bufs[n], 0, v->fec->rsn << DM_VERITY_FEC_BUF_RS_BITS); 355 356 memset(fio->erasures, 0, sizeof(fio->erasures)); 357} 358 359/* 360 * Decode all RS blocks in a single data block and return the target block 361 * (indicated by @offset) in fio->output. If @use_erasures is non-zero, uses 362 * hashes to locate erasures. 363 */ 364static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io, 365 struct dm_verity_fec_io *fio, u64 rsb, u64 offset, 366 bool use_erasures) 367{ 368 int r, neras = 0; 369 unsigned int pos; 370 371 r = fec_alloc_bufs(v, fio); 372 if (unlikely(r < 0)) 373 return r; 374 375 for (pos = 0; pos < 1 << v->data_dev_block_bits; ) { 376 fec_init_bufs(v, fio); 377 378 r = fec_read_bufs(v, io, rsb, offset, pos, 379 use_erasures ? &neras : NULL); 380 if (unlikely(r < 0)) 381 return r; 382 383 r = fec_decode_bufs(v, io, fio, rsb, r, pos, neras); 384 if (r < 0) 385 return r; 386 387 pos += fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS; 388 } 389 390 /* Always re-validate the corrected block against the expected hash */ 391 r = verity_hash(v, verity_io_hash_req(v, io), fio->output, 392 1 << v->data_dev_block_bits, 393 verity_io_real_digest(v, io), true); 394 if (unlikely(r < 0)) 395 return r; 396 397 if (memcmp(verity_io_real_digest(v, io), verity_io_want_digest(v, io), 398 v->digest_size)) { 399 DMERR_LIMIT("%s: FEC %llu: failed to correct (%d erasures)", 400 v->data_dev->name, (unsigned long long)rsb, neras); 401 return -EILSEQ; 402 } 403 404 return 0; 405} 406 407static int fec_bv_copy(struct dm_verity *v, struct dm_verity_io *io, u8 *data, 408 size_t len) 409{ 410 struct dm_verity_fec_io *fio = fec_io(io); 411 412 memcpy(data, &fio->output[fio->output_pos], len); 413 fio->output_pos += len; 414 415 return 0; 416} 417 418/* 419 * Correct errors in a block. Copies corrected block to dest if non-NULL, 420 * otherwise to a bio_vec starting from iter. 421 */ 422int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 423 enum verity_block_type type, sector_t block, u8 *dest, 424 struct bvec_iter *iter) 425{ 426 int r; 427 struct dm_verity_fec_io *fio = fec_io(io); 428 u64 offset, res, rsb; 429 430 if (!verity_fec_is_enabled(v)) 431 return -EOPNOTSUPP; 432 433 if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) { 434 DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name); 435 return -EIO; 436 } 437 438 fio->level++; 439 440 if (type == DM_VERITY_BLOCK_TYPE_METADATA) 441 block = block - v->hash_start + v->data_blocks; 442 443 /* 444 * For RS(M, N), the continuous FEC data is divided into blocks of N 445 * bytes. Since block size may not be divisible by N, the last block 446 * is zero padded when decoding. 447 * 448 * Each byte of the block is covered by a different RS(M, N) code, 449 * and each code is interleaved over N blocks to make it less likely 450 * that bursty corruption will leave us in unrecoverable state. 451 */ 452 453 offset = block << v->data_dev_block_bits; 454 res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits); 455 456 /* 457 * The base RS block we can feed to the interleaver to find out all 458 * blocks required for decoding. 459 */ 460 rsb = offset - res * (v->fec->rounds << v->data_dev_block_bits); 461 462 /* 463 * Locating erasures is slow, so attempt to recover the block without 464 * them first. Do a second attempt with erasures if the corruption is 465 * bad enough. 466 */ 467 r = fec_decode_rsb(v, io, fio, rsb, offset, false); 468 if (r < 0) { 469 r = fec_decode_rsb(v, io, fio, rsb, offset, true); 470 if (r < 0) 471 goto done; 472 } 473 474 if (dest) 475 memcpy(dest, fio->output, 1 << v->data_dev_block_bits); 476 else if (iter) { 477 fio->output_pos = 0; 478 r = verity_for_bv_block(v, io, iter, fec_bv_copy); 479 } 480 481done: 482 fio->level--; 483 return r; 484} 485 486/* 487 * Clean up per-bio data. 488 */ 489void verity_fec_finish_io(struct dm_verity_io *io) 490{ 491 unsigned int n; 492 struct dm_verity_fec *f = io->v->fec; 493 struct dm_verity_fec_io *fio = fec_io(io); 494 495 if (!verity_fec_is_enabled(io->v)) 496 return; 497 498 mempool_free(fio->rs, &f->rs_pool); 499 500 fec_for_each_prealloc_buffer(n) 501 mempool_free(fio->bufs[n], &f->prealloc_pool); 502 503 fec_for_each_extra_buffer(fio, n) 504 mempool_free(fio->bufs[n], &f->extra_pool); 505 506 mempool_free(fio->output, &f->output_pool); 507} 508 509/* 510 * Initialize per-bio data. 511 */ 512void verity_fec_init_io(struct dm_verity_io *io) 513{ 514 struct dm_verity_fec_io *fio = fec_io(io); 515 516 if (!verity_fec_is_enabled(io->v)) 517 return; 518 519 fio->rs = NULL; 520 memset(fio->bufs, 0, sizeof(fio->bufs)); 521 fio->nbufs = 0; 522 fio->output = NULL; 523 fio->level = 0; 524} 525 526/* 527 * Append feature arguments and values to the status table. 528 */ 529unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, 530 char *result, unsigned int maxlen) 531{ 532 if (!verity_fec_is_enabled(v)) 533 return sz; 534 535 DMEMIT(" " DM_VERITY_OPT_FEC_DEV " %s " 536 DM_VERITY_OPT_FEC_BLOCKS " %llu " 537 DM_VERITY_OPT_FEC_START " %llu " 538 DM_VERITY_OPT_FEC_ROOTS " %d", 539 v->fec->dev->name, 540 (unsigned long long)v->fec->blocks, 541 (unsigned long long)v->fec->start, 542 v->fec->roots); 543 544 return sz; 545} 546 547void verity_fec_dtr(struct dm_verity *v) 548{ 549 struct dm_verity_fec *f = v->fec; 550 551 if (!verity_fec_is_enabled(v)) 552 goto out; 553 554 mempool_exit(&f->rs_pool); 555 mempool_exit(&f->prealloc_pool); 556 mempool_exit(&f->extra_pool); 557 mempool_exit(&f->output_pool); 558 kmem_cache_destroy(f->cache); 559 560 if (f->data_bufio) 561 dm_bufio_client_destroy(f->data_bufio); 562 if (f->bufio) 563 dm_bufio_client_destroy(f->bufio); 564 565 if (f->dev) 566 dm_put_device(v->ti, f->dev); 567out: 568 kfree(f); 569 v->fec = NULL; 570} 571 572static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data) 573{ 574 struct dm_verity *v = pool_data; 575 576 return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask); 577} 578 579static void fec_rs_free(void *element, void *pool_data) 580{ 581 struct rs_control *rs = element; 582 583 if (rs) 584 free_rs(rs); 585} 586 587bool verity_is_fec_opt_arg(const char *arg_name) 588{ 589 return (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV) || 590 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS) || 591 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_START) || 592 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)); 593} 594 595int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 596 unsigned int *argc, const char *arg_name) 597{ 598 int r; 599 struct dm_target *ti = v->ti; 600 const char *arg_value; 601 unsigned long long num_ll; 602 unsigned char num_c; 603 char dummy; 604 605 if (!*argc) { 606 ti->error = "FEC feature arguments require a value"; 607 return -EINVAL; 608 } 609 610 arg_value = dm_shift_arg(as); 611 (*argc)--; 612 613 if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV)) { 614 r = dm_get_device(ti, arg_value, BLK_OPEN_READ, &v->fec->dev); 615 if (r) { 616 ti->error = "FEC device lookup failed"; 617 return r; 618 } 619 620 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS)) { 621 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 622 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 623 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 624 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 625 return -EINVAL; 626 } 627 v->fec->blocks = num_ll; 628 629 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_START)) { 630 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 || 631 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) >> 632 (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) { 633 ti->error = "Invalid " DM_VERITY_OPT_FEC_START; 634 return -EINVAL; 635 } 636 v->fec->start = num_ll; 637 638 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) { 639 if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c || 640 num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) || 641 num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) { 642 ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS; 643 return -EINVAL; 644 } 645 v->fec->roots = num_c; 646 647 } else { 648 ti->error = "Unrecognized verity FEC feature request"; 649 return -EINVAL; 650 } 651 652 return 0; 653} 654 655/* 656 * Allocate dm_verity_fec for v->fec. Must be called before verity_fec_ctr. 657 */ 658int verity_fec_ctr_alloc(struct dm_verity *v) 659{ 660 struct dm_verity_fec *f; 661 662 f = kzalloc(sizeof(struct dm_verity_fec), GFP_KERNEL); 663 if (!f) { 664 v->ti->error = "Cannot allocate FEC structure"; 665 return -ENOMEM; 666 } 667 v->fec = f; 668 669 return 0; 670} 671 672/* 673 * Validate arguments and preallocate memory. Must be called after arguments 674 * have been parsed using verity_fec_parse_opt_args. 675 */ 676int verity_fec_ctr(struct dm_verity *v) 677{ 678 struct dm_verity_fec *f = v->fec; 679 struct dm_target *ti = v->ti; 680 u64 hash_blocks, fec_blocks; 681 int ret; 682 683 if (!verity_fec_is_enabled(v)) { 684 verity_fec_dtr(v); 685 return 0; 686 } 687 688 /* 689 * FEC is computed over data blocks, possible metadata, and 690 * hash blocks. In other words, FEC covers total of fec_blocks 691 * blocks consisting of the following: 692 * 693 * data blocks | hash blocks | metadata (optional) 694 * 695 * We allow metadata after hash blocks to support a use case 696 * where all data is stored on the same device and FEC covers 697 * the entire area. 698 * 699 * If metadata is included, we require it to be available on the 700 * hash device after the hash blocks. 701 */ 702 703 hash_blocks = v->hash_blocks - v->hash_start; 704 705 /* 706 * Require matching block sizes for data and hash devices for 707 * simplicity. 708 */ 709 if (v->data_dev_block_bits != v->hash_dev_block_bits) { 710 ti->error = "Block sizes must match to use FEC"; 711 return -EINVAL; 712 } 713 714 if (!f->roots) { 715 ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS; 716 return -EINVAL; 717 } 718 f->rsn = DM_VERITY_FEC_RSM - f->roots; 719 720 if (!f->blocks) { 721 ti->error = "Missing " DM_VERITY_OPT_FEC_BLOCKS; 722 return -EINVAL; 723 } 724 725 f->rounds = f->blocks; 726 if (sector_div(f->rounds, f->rsn)) 727 f->rounds++; 728 729 /* 730 * Due to optional metadata, f->blocks can be larger than 731 * data_blocks and hash_blocks combined. 732 */ 733 if (f->blocks < v->data_blocks + hash_blocks || !f->rounds) { 734 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS; 735 return -EINVAL; 736 } 737 738 /* 739 * Metadata is accessed through the hash device, so we require 740 * it to be large enough. 741 */ 742 f->hash_blocks = f->blocks - v->data_blocks; 743 if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) { 744 ti->error = "Hash device is too small for " 745 DM_VERITY_OPT_FEC_BLOCKS; 746 return -E2BIG; 747 } 748 749 if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1)) 750 f->io_size = 1 << v->data_dev_block_bits; 751 else 752 f->io_size = v->fec->roots << SECTOR_SHIFT; 753 754 f->bufio = dm_bufio_client_create(f->dev->bdev, 755 f->io_size, 756 1, 0, NULL, NULL, 0); 757 if (IS_ERR(f->bufio)) { 758 ti->error = "Cannot initialize FEC bufio client"; 759 return PTR_ERR(f->bufio); 760 } 761 762 dm_bufio_set_sector_offset(f->bufio, f->start << (v->data_dev_block_bits - SECTOR_SHIFT)); 763 764 fec_blocks = div64_u64(f->rounds * f->roots, v->fec->roots << SECTOR_SHIFT); 765 if (dm_bufio_get_device_size(f->bufio) < fec_blocks) { 766 ti->error = "FEC device is too small"; 767 return -E2BIG; 768 } 769 770 f->data_bufio = dm_bufio_client_create(v->data_dev->bdev, 771 1 << v->data_dev_block_bits, 772 1, 0, NULL, NULL, 0); 773 if (IS_ERR(f->data_bufio)) { 774 ti->error = "Cannot initialize FEC data bufio client"; 775 return PTR_ERR(f->data_bufio); 776 } 777 778 if (dm_bufio_get_device_size(f->data_bufio) < v->data_blocks) { 779 ti->error = "Data device is too small"; 780 return -E2BIG; 781 } 782 783 /* Preallocate an rs_control structure for each worker thread */ 784 ret = mempool_init(&f->rs_pool, num_online_cpus(), fec_rs_alloc, 785 fec_rs_free, (void *) v); 786 if (ret) { 787 ti->error = "Cannot allocate RS pool"; 788 return ret; 789 } 790 791 f->cache = kmem_cache_create("dm_verity_fec_buffers", 792 f->rsn << DM_VERITY_FEC_BUF_RS_BITS, 793 0, 0, NULL); 794 if (!f->cache) { 795 ti->error = "Cannot create FEC buffer cache"; 796 return -ENOMEM; 797 } 798 799 /* Preallocate DM_VERITY_FEC_BUF_PREALLOC buffers for each thread */ 800 ret = mempool_init_slab_pool(&f->prealloc_pool, num_online_cpus() * 801 DM_VERITY_FEC_BUF_PREALLOC, 802 f->cache); 803 if (ret) { 804 ti->error = "Cannot allocate FEC buffer prealloc pool"; 805 return ret; 806 } 807 808 ret = mempool_init_slab_pool(&f->extra_pool, 0, f->cache); 809 if (ret) { 810 ti->error = "Cannot allocate FEC buffer extra pool"; 811 return ret; 812 } 813 814 /* Preallocate an output buffer for each thread */ 815 ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(), 816 1 << v->data_dev_block_bits); 817 if (ret) { 818 ti->error = "Cannot allocate FEC output pool"; 819 return ret; 820 } 821 822 /* Reserve space for our per-bio data */ 823 ti->per_io_data_size += sizeof(struct dm_verity_fec_io); 824 825 return 0; 826} 827