fs/erofs/zmap.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 #include "internal.h"
   3
   4 static int z_erofs_do_map_blocks(struct erofs_inode *vi,
   5                                  struct erofs_map_blocks *map,
   6                                  int flags);
   7
   8 int z_erofs_fill_inode(struct erofs_inode *vi)
   9 {
  10         if (!erofs_sb_has_big_pcluster() &&
  11             !erofs_sb_has_ztailpacking() && !erofs_sb_has_fragments() &&
  12             vi->datalayout == EROFS_INODE_COMPRESSED_FULL) {
  13                 vi->z_advise = 0;
  14                 vi->z_algorithmtype[0] = 0;
  15                 vi->z_algorithmtype[1] = 0;
  16                 vi->z_logical_clusterbits = sbi.blkszbits;
  17
  18                 vi->flags |= EROFS_I_Z_INITED;
  19         }
  20         return 0;
  21 }
  22
  23 static int z_erofs_fill_inode_lazy(struct erofs_inode *vi)
  24 {
  25         int ret;
  26         erofs_off_t pos;
  27         struct z_erofs_map_header *h;
  28         char buf[sizeof(struct z_erofs_map_header)];
  29
  30         if (vi->flags & EROFS_I_Z_INITED)
  31                 return 0;
  32
  33         pos = round_up(iloc(vi->nid) + vi->inode_isize + vi->xattr_isize, 8);
  34         ret = erofs_dev_read(0, buf, pos, sizeof(buf));
  35         if (ret < 0)
  36                 return -EIO;
  37
  38         h = (struct z_erofs_map_header *)buf;
  39         /*
  40          * if the highest bit of the 8-byte map header is set, the whole file
  41          * is stored in the packed inode. The rest bits keeps z_fragmentoff.
  42          */
  43         if (h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT) {
  44                 vi->z_advise = Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
  45                 vi->fragmentoff = le64_to_cpu(*(__le64 *)h) ^ (1ULL << 63);
  46                 vi->z_tailextent_headlcn = 0;
  47                 goto out;
  48         }
  49
  50         vi->z_advise = le16_to_cpu(h->h_advise);
  51         vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
  52         vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
  53
  54         if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX) {
  55                 erofs_err("unknown compression format %u for nid %llu",
  56                           vi->z_algorithmtype[0], (unsigned long long)vi->nid);
  57                 return -EOPNOTSUPP;
  58         }
  59
  60         vi->z_logical_clusterbits = sbi.blkszbits + (h->h_clusterbits & 7);
  61         if (vi->datalayout == EROFS_INODE_COMPRESSED_COMPACT &&
  62             !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
  63             !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
  64                 erofs_err("big pcluster head1/2 of compact indexes should be consistent for nid %llu",
  65                           vi->nid * 1ULL);
  66                 return -EFSCORRUPTED;
  67         }
  68
  69         if (vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER) {
  70                 struct erofs_map_blocks map = { .index = UINT_MAX };
  71
  72                 vi->idata_size = le16_to_cpu(h->h_idata_size);
  73                 ret = z_erofs_do_map_blocks(vi, &map,
  74                                             EROFS_GET_BLOCKS_FINDTAIL);
  75                 if (!map.m_plen ||
  76                     erofs_blkoff(map.m_pa) + map.m_plen > erofs_blksiz()) {
  77                         erofs_err("invalid tail-packing pclustersize %llu",
  78                                   map.m_plen | 0ULL);
  79                         return -EFSCORRUPTED;
  80                 }
  81                 if (ret < 0)
  82                         return ret;
  83         }
  84         if (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER &&
  85             !(h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT)) {
  86                 struct erofs_map_blocks map = { .index = UINT_MAX };
  87
  88                 vi->fragmentoff = le32_to_cpu(h->h_fragmentoff);
  89                 ret = z_erofs_do_map_blocks(vi, &map,
  90                                             EROFS_GET_BLOCKS_FINDTAIL);
  91                 if (ret < 0)
  92                         return ret;
  93         }
  94 out:
  95         vi->flags |= EROFS_I_Z_INITED;
  96         return 0;
  97 }
  98
  99 struct z_erofs_maprecorder {
 100         struct erofs_inode *inode;
 101         struct erofs_map_blocks *map;
 102         void *kaddr;
 103
 104         unsigned long lcn;
 105         /* compression extent information gathered */
 106         u8  type, headtype;
 107         u16 clusterofs;
 108         u16 delta[2];
 109         erofs_blk_t pblk, compressedblks;
 110         erofs_off_t nextpackoff;
 111         bool partialref;
 112 };
 113
 114 static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
 115                                   erofs_blk_t eblk)
 116 {
 117         int ret;
 118         struct erofs_map_blocks *const map = m->map;
 119         char *mpage = map->mpage;
 120
 121         if (map->index == eblk)
 122                 return 0;
 123
 124         ret = erofs_blk_read(mpage, eblk, 1);
 125         if (ret < 0)
 126                 return -EIO;
 127
 128         map->index = eblk;
 129
 130         return 0;
 131 }
 132
 133 static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 134                                          unsigned long lcn)
 135 {
 136         struct erofs_inode *const vi = m->inode;
 137         const erofs_off_t ibase = iloc(vi->nid);
 138         const erofs_off_t pos = Z_EROFS_FULL_INDEX_ALIGN(ibase +
 139                         vi->inode_isize + vi->xattr_isize) +
 140                 lcn * sizeof(struct z_erofs_lcluster_index);
 141         struct z_erofs_lcluster_index *di;
 142         unsigned int advise, type;
 143         int err;
 144
 145         err = z_erofs_reload_indexes(m, erofs_blknr(pos));
 146         if (err)
 147                 return err;
 148
 149         m->nextpackoff = pos + sizeof(struct z_erofs_lcluster_index);
 150         m->lcn = lcn;
 151         di = m->kaddr + erofs_blkoff(pos);
 152
 153         advise = le16_to_cpu(di->di_advise);
 154         type = (advise >> Z_EROFS_LI_LCLUSTER_TYPE_BIT) &
 155                 ((1 << Z_EROFS_LI_LCLUSTER_TYPE_BITS) - 1);
 156         switch (type) {
 157         case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
 158                 m->clusterofs = 1 << vi->z_logical_clusterbits;
 159                 m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
 160                 if (m->delta[0] & Z_EROFS_LI_D0_CBLKCNT) {
 161                         if (!(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
 162                                 DBG_BUGON(1);
 163                                 return -EFSCORRUPTED;
 164                         }
 165                         m->compressedblks = m->delta[0] &
 166                                 ~Z_EROFS_LI_D0_CBLKCNT;
 167                         m->delta[0] = 1;
 168                 }
 169                 m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
 170                 break;
 171         case Z_EROFS_LCLUSTER_TYPE_PLAIN:
 172         case Z_EROFS_LCLUSTER_TYPE_HEAD1:
 173                 if (advise & Z_EROFS_LI_PARTIAL_REF)
 174                         m->partialref = true;
 175                 m->clusterofs = le16_to_cpu(di->di_clusterofs);
 176                 m->pblk = le32_to_cpu(di->di_u.blkaddr);
 177                 break;
 178         default:
 179                 DBG_BUGON(1);
 180                 return -EOPNOTSUPP;
 181         }
 182         m->type = type;
 183         return 0;
 184 }
 185
 186 static unsigned int decode_compactedbits(unsigned int lobits,
 187                                          unsigned int lomask,
 188                                          u8 *in, unsigned int pos, u8 *type)
 189 {
 190         const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
 191         const unsigned int lo = v & lomask;
 192
 193         *type = (v >> lobits) & 3;
 194         return lo;
 195 }
 196
 197 static int get_compacted_la_distance(unsigned int lclusterbits,
 198                                      unsigned int encodebits,
 199                                      unsigned int vcnt, u8 *in, int i)
 200 {
 201         const unsigned int lomask = (1 << lclusterbits) - 1;
 202         unsigned int lo, d1 = 0;
 203         u8 type;
 204
 205         DBG_BUGON(i >= vcnt);
 206
 207         do {
 208                 lo = decode_compactedbits(lclusterbits, lomask,
 209                                           in, encodebits * i, &type);
 210
 211                 if (type != Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 212                         return d1;
 213                 ++d1;
 214         } while (++i < vcnt);
 215
 216         /* vcnt - 1 (Z_EROFS_LCLUSTER_TYPE_NONHEAD) item */
 217         if (!(lo & Z_EROFS_LI_D0_CBLKCNT))
 218                 d1 += lo - 1;
 219         return d1;
 220 }
 221
 222 static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 223                                   unsigned int amortizedshift,
 224                                   erofs_off_t pos, bool lookahead)
 225 {
 226         struct erofs_inode *const vi = m->inode;
 227         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 228         const unsigned int lomask = (1 << lclusterbits) - 1;
 229         unsigned int vcnt, base, lo, encodebits, nblk, eofs;
 230         int i;
 231         u8 *in, type;
 232         bool big_pcluster;
 233
 234         if (1 << amortizedshift == 4)
 235                 vcnt = 2;
 236         else if (1 << amortizedshift == 2 && lclusterbits == 12)
 237                 vcnt = 16;
 238         else
 239                 return -EOPNOTSUPP;
 240
 241         /* it doesn't equal to round_up(..) */
 242         m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
 243                          (vcnt << amortizedshift);
 244         big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
 245         encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
 246         eofs = erofs_blkoff(pos);
 247         base = round_down(eofs, vcnt << amortizedshift);
 248         in = m->kaddr + base;
 249
 250         i = (eofs - base) >> amortizedshift;
 251
 252         lo = decode_compactedbits(lclusterbits, lomask,
 253                                   in, encodebits * i, &type);
 254         m->type = type;
 255         if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 256                 m->clusterofs = 1 << lclusterbits;
 257
 258                 /* figure out lookahead_distance: delta[1] if needed */
 259                 if (lookahead)
 260                         m->delta[1] = get_compacted_la_distance(lclusterbits,
 261                                                                 encodebits, vcnt, in, i);
 262                 if (lo & Z_EROFS_LI_D0_CBLKCNT) {
 263                         if (!big_pcluster) {
 264                                 DBG_BUGON(1);
 265                                 return -EFSCORRUPTED;
 266                         }
 267                         m->compressedblks = lo & ~Z_EROFS_LI_D0_CBLKCNT;
 268                         m->delta[0] = 1;
 269                         return 0;
 270                 } else if (i + 1 != (int)vcnt) {
 271                         m->delta[0] = lo;
 272                         return 0;
 273                 }
 274                 /*
 275                  * since the last lcluster in the pack is special,
 276                  * of which lo saves delta[1] rather than delta[0].
 277                  * Hence, get delta[0] by the previous lcluster indirectly.
 278                  */
 279                 lo = decode_compactedbits(lclusterbits, lomask,
 280                                           in, encodebits * (i - 1), &type);
 281                 if (type != Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 282                         lo = 0;
 283                 else if (lo & Z_EROFS_LI_D0_CBLKCNT)
 284                         lo = 1;
 285                 m->delta[0] = lo + 1;
 286                 return 0;
 287         }
 288         m->clusterofs = lo;
 289         m->delta[0] = 0;
 290         /* figout out blkaddr (pblk) for HEAD lclusters */
 291         if (!big_pcluster) {
 292                 nblk = 1;
 293                 while (i > 0) {
 294                         --i;
 295                         lo = decode_compactedbits(lclusterbits, lomask,
 296                                                   in, encodebits * i, &type);
 297                         if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD)
 298                                 i -= lo;
 299
 300                         if (i >= 0)
 301                                 ++nblk;
 302                 }
 303         } else {
 304                 nblk = 0;
 305                 while (i > 0) {
 306                         --i;
 307                         lo = decode_compactedbits(lclusterbits, lomask,
 308                                                   in, encodebits * i, &type);
 309                         if (type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 310                                 if (lo & Z_EROFS_LI_D0_CBLKCNT) {
 311                                         --i;
 312                                         nblk += lo & ~Z_EROFS_LI_D0_CBLKCNT;
 313                                         continue;
 314                                 }
 315                                 if (lo <= 1) {
 316                                         DBG_BUGON(1);
 317                                         /* --i; ++nblk; continue; */
 318                                         return -EFSCORRUPTED;
 319                                 }
 320                                 i -= lo - 2;
 321                                 continue;
 322                         }
 323                         ++nblk;
 324                 }
 325         }
 326         in += (vcnt << amortizedshift) - sizeof(__le32);
 327         m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
 328         return 0;
 329 }
 330
 331 static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 332                                             unsigned long lcn, bool lookahead)
 333 {
 334         struct erofs_inode *const vi = m->inode;
 335         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 336         const erofs_off_t ebase = round_up(iloc(vi->nid) + vi->inode_isize +
 337                                            vi->xattr_isize, 8) +
 338                 sizeof(struct z_erofs_map_header);
 339         const unsigned int totalidx = BLK_ROUND_UP(vi->i_size);
 340         unsigned int compacted_4b_initial, compacted_2b;
 341         unsigned int amortizedshift;
 342         erofs_off_t pos;
 343         int err;
 344
 345         if (lclusterbits != 12)
 346                 return -EOPNOTSUPP;
 347
 348         if (lcn >= totalidx)
 349                 return -EINVAL;
 350
 351         m->lcn = lcn;
 352         /* used to align to 32-byte (compacted_2b) alignment */
 353         compacted_4b_initial = (32 - ebase % 32) / 4;
 354         if (compacted_4b_initial == 32 / 4)
 355                 compacted_4b_initial = 0;
 356
 357         if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&
 358             compacted_4b_initial < totalidx)
 359                 compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
 360         else
 361                 compacted_2b = 0;
 362
 363         pos = ebase;
 364         if (lcn < compacted_4b_initial) {
 365                 amortizedshift = 2;
 366                 goto out;
 367         }
 368         pos += compacted_4b_initial * 4;
 369         lcn -= compacted_4b_initial;
 370
 371         if (lcn < compacted_2b) {
 372                 amortizedshift = 1;
 373                 goto out;
 374         }
 375         pos += compacted_2b * 2;
 376         lcn -= compacted_2b;
 377         amortizedshift = 2;
 378 out:
 379         pos += lcn * (1 << amortizedshift);
 380         err = z_erofs_reload_indexes(m, erofs_blknr(pos));
 381         if (err)
 382                 return err;
 383         return unpack_compacted_index(m, amortizedshift, pos, lookahead);
 384 }
 385
 386 static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 387                                           unsigned int lcn, bool lookahead)
 388 {
 389         const unsigned int datamode = m->inode->datalayout;
 390
 391         if (datamode == EROFS_INODE_COMPRESSED_FULL)
 392                 return legacy_load_cluster_from_disk(m, lcn);
 393
 394         if (datamode == EROFS_INODE_COMPRESSED_COMPACT)
 395                 return compacted_load_cluster_from_disk(m, lcn, lookahead);
 396
 397         return -EINVAL;
 398 }
 399
 400 static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 401                                    unsigned int lookback_distance)
 402 {
 403         struct erofs_inode *const vi = m->inode;
 404         struct erofs_map_blocks *const map = m->map;
 405         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 406         unsigned long lcn = m->lcn;
 407         int err;
 408
 409         if (lcn < lookback_distance) {
 410                 erofs_err("bogus lookback distance @ nid %llu",
 411                           (unsigned long long)vi->nid);
 412                 DBG_BUGON(1);
 413                 return -EFSCORRUPTED;
 414         }
 415
 416         /* load extent head logical cluster if needed */
 417         lcn -= lookback_distance;
 418         err = z_erofs_load_cluster_from_disk(m, lcn, false);
 419         if (err)
 420                 return err;
 421
 422         switch (m->type) {
 423         case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
 424                 if (!m->delta[0]) {
 425                         erofs_err("invalid lookback distance 0 @ nid %llu",
 426                                   (unsigned long long)vi->nid);
 427                         DBG_BUGON(1);
 428                         return -EFSCORRUPTED;
 429                 }
 430                 return z_erofs_extent_lookback(m, m->delta[0]);
 431         case Z_EROFS_LCLUSTER_TYPE_PLAIN:
 432         case Z_EROFS_LCLUSTER_TYPE_HEAD1:
 433                 m->headtype = m->type;
 434                 map->m_la = (lcn << lclusterbits) | m->clusterofs;
 435                 break;
 436         default:
 437                 erofs_err("unknown type %u @ lcn %lu of nid %llu",
 438                           m->type, lcn, (unsigned long long)vi->nid);
 439                 DBG_BUGON(1);
 440                 return -EOPNOTSUPP;
 441         }
 442         return 0;
 443 }
 444
 445 static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 446                                             unsigned int initial_lcn)
 447 {
 448         struct erofs_inode *const vi = m->inode;
 449         struct erofs_map_blocks *const map = m->map;
 450         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 451         unsigned long lcn;
 452         int err;
 453
 454         DBG_BUGON(m->type != Z_EROFS_LCLUSTER_TYPE_PLAIN &&
 455                   m->type != Z_EROFS_LCLUSTER_TYPE_HEAD1);
 456
 457         if (m->headtype == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
 458             !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) {
 459                 map->m_plen = 1 << lclusterbits;
 460                 return 0;
 461         }
 462
 463         lcn = m->lcn + 1;
 464         if (m->compressedblks)
 465                 goto out;
 466
 467         err = z_erofs_load_cluster_from_disk(m, lcn, false);
 468         if (err)
 469                 return err;
 470
 471         /*
 472          * If the 1st NONHEAD lcluster has already been handled initially w/o
 473          * valid compressedblks, which means at least it mustn't be CBLKCNT, or
 474          * an internal implemenatation error is detected.
 475          *
 476          * The following code can also handle it properly anyway, but let's
 477          * BUG_ON in the debugging mode only for developers to notice that.
 478          */
 479         DBG_BUGON(lcn == initial_lcn &&
 480                   m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD);
 481
 482         switch (m->type) {
 483         case Z_EROFS_LCLUSTER_TYPE_PLAIN:
 484         case Z_EROFS_LCLUSTER_TYPE_HEAD1:
 485                 /*
 486                  * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
 487                  * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
 488                  */
 489                 m->compressedblks = 1 << (lclusterbits - sbi.blkszbits);
 490                 break;
 491         case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
 492                 if (m->delta[0] != 1)
 493                         goto err_bonus_cblkcnt;
 494                 if (m->compressedblks)
 495                         break;
 496                 /* fallthrough */
 497         default:
 498                 erofs_err("cannot found CBLKCNT @ lcn %lu of nid %llu",
 499                           lcn, vi->nid | 0ULL);
 500                 DBG_BUGON(1);
 501                 return -EFSCORRUPTED;
 502         }
 503 out:
 504         map->m_plen = m->compressedblks << sbi.blkszbits;
 505         return 0;
 506 err_bonus_cblkcnt:
 507         erofs_err("bogus CBLKCNT @ lcn %lu of nid %llu",
 508                   lcn, vi->nid | 0ULL);
 509         DBG_BUGON(1);
 510         return -EFSCORRUPTED;
 511 }
 512
 513 static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 514 {
 515         struct erofs_inode *const vi = m->inode;
 516         struct erofs_map_blocks *map = m->map;
 517         unsigned int lclusterbits = vi->z_logical_clusterbits;
 518         u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
 519         int err;
 520
 521         do {
 522                 /* handle the last EOF pcluster (no next HEAD lcluster) */
 523                 if ((lcn << lclusterbits) >= vi->i_size) {
 524                         map->m_llen = vi->i_size - map->m_la;
 525                         return 0;
 526                 }
 527
 528                 err = z_erofs_load_cluster_from_disk(m, lcn, true);
 529                 if (err)
 530                         return err;
 531
 532                 if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 533                         DBG_BUGON(!m->delta[1] &&
 534                                   m->clusterofs != 1 << lclusterbits);
 535                 } else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
 536                            m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1) {
 537                         /* go on until the next HEAD lcluster */
 538                         if (lcn != headlcn)
 539                                 break;
 540                         m->delta[1] = 1;
 541                 } else {
 542                         erofs_err("unknown type %u @ lcn %llu of nid %llu",
 543                                   m->type, lcn | 0ULL,
 544                                   (unsigned long long)vi->nid);
 545                         DBG_BUGON(1);
 546                         return -EOPNOTSUPP;
 547                 }
 548                 lcn += m->delta[1];
 549         } while (m->delta[1]);
 550
 551         map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
 552         return 0;
 553 }
 554
 555 static int z_erofs_do_map_blocks(struct erofs_inode *vi,
 556                                  struct erofs_map_blocks *map,
 557                                  int flags)
 558 {
 559         bool ztailpacking = vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER;
 560         bool fragment = vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
 561         struct z_erofs_maprecorder m = {
 562                 .inode = vi,
 563                 .map = map,
 564                 .kaddr = map->mpage,
 565         };
 566         int err = 0;
 567         unsigned int lclusterbits, endoff;
 568         unsigned long initial_lcn;
 569         unsigned long long ofs, end;
 570
 571         lclusterbits = vi->z_logical_clusterbits;
 572         ofs = flags & EROFS_GET_BLOCKS_FINDTAIL ? vi->i_size - 1 : map->m_la;
 573         initial_lcn = ofs >> lclusterbits;
 574         endoff = ofs & ((1 << lclusterbits) - 1);
 575
 576         err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
 577         if (err)
 578                 goto out;
 579
 580         if (ztailpacking && (flags & EROFS_GET_BLOCKS_FINDTAIL))
 581                 vi->z_idataoff = m.nextpackoff;
 582
 583         map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
 584         end = (m.lcn + 1ULL) << lclusterbits;
 585         switch (m.type) {
 586         case Z_EROFS_LCLUSTER_TYPE_PLAIN:
 587         case Z_EROFS_LCLUSTER_TYPE_HEAD1:
 588                 if (endoff >= m.clusterofs) {
 589                         m.headtype = m.type;
 590                         map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
 591                         break;
 592                 }
 593                 /* m.lcn should be >= 1 if endoff < m.clusterofs */
 594                 if (!m.lcn) {
 595                         erofs_err("invalid logical cluster 0 at nid %llu",
 596                                   (unsigned long long)vi->nid);
 597                         err = -EFSCORRUPTED;
 598                         goto out;
 599                 }
 600                 end = (m.lcn << lclusterbits) | m.clusterofs;
 601                 map->m_flags |= EROFS_MAP_FULL_MAPPED;
 602                 m.delta[0] = 1;
 603                 /* fallthrough */
 604         case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
 605                 /* get the correspoinding first chunk */
 606                 err = z_erofs_extent_lookback(&m, m.delta[0]);
 607                 if (err)
 608                         goto out;
 609                 break;
 610         default:
 611                 erofs_err("unknown type %u @ offset %llu of nid %llu",
 612                           m.type, ofs, (unsigned long long)vi->nid);
 613                 err = -EOPNOTSUPP;
 614                 goto out;
 615         }
 616         if (m.partialref)
 617                 map->m_flags |= EROFS_MAP_PARTIAL_REF;
 618         map->m_llen = end - map->m_la;
 619         if (flags & EROFS_GET_BLOCKS_FINDTAIL) {
 620                 vi->z_tailextent_headlcn = m.lcn;
 621                 /* for non-compact indexes, fragmentoff is 64 bits */
 622                 if (fragment && vi->datalayout == EROFS_INODE_COMPRESSED_FULL)
 623                         vi->fragmentoff |= (u64)m.pblk << 32;
 624         }
 625         if (ztailpacking && m.lcn == vi->z_tailextent_headlcn) {
 626                 map->m_flags |= EROFS_MAP_META;
 627                 map->m_pa = vi->z_idataoff;
 628                 map->m_plen = vi->z_idata_size;
 629         } else if (fragment && m.lcn == vi->z_tailextent_headlcn) {
 630                 map->m_flags |= EROFS_MAP_FRAGMENT;
 631         } else {
 632                 map->m_pa = erofs_pos(m.pblk);
 633                 err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
 634                 if (err)
 635                         goto out;
 636         }
 637
 638         if (m.headtype == Z_EROFS_LCLUSTER_TYPE_PLAIN) {
 639                 if (map->m_llen > map->m_plen) {
 640                         DBG_BUGON(1);
 641                         err = -EFSCORRUPTED;
 642                         goto out;
 643                 }
 644                 if (vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER)
 645                         map->m_algorithmformat =
 646                                 Z_EROFS_COMPRESSION_INTERLACED;
 647                 else
 648                         map->m_algorithmformat =
 649                                 Z_EROFS_COMPRESSION_SHIFTED;
 650         } else {
 651                 map->m_algorithmformat = vi->z_algorithmtype[0];
 652         }
 653
 654         if (flags & EROFS_GET_BLOCKS_FIEMAP) {
 655                 err = z_erofs_get_extent_decompressedlen(&m);
 656                 if (!err)
 657                         map->m_flags |= EROFS_MAP_FULL_MAPPED;
 658         }
 659
 660 out:
 661         erofs_dbg("m_la %" PRIu64 " m_pa %" PRIu64 " m_llen %" PRIu64 " m_plen %" PRIu64 " m_flags 0%o",
 662                   map->m_la, map->m_pa,
 663                   map->m_llen, map->m_plen, map->m_flags);
 664         return err;
 665 }
 666
 667 int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 668                             struct erofs_map_blocks *map,
 669                             int flags)
 670 {
 671         int err = 0;
 672
 673         /* when trying to read beyond EOF, leave it unmapped */
 674         if (map->m_la >= vi->i_size) {
 675                 map->m_llen = map->m_la + 1 - vi->i_size;
 676                 map->m_la = vi->i_size;
 677                 map->m_flags = 0;
 678                 goto out;
 679         }
 680
 681         err = z_erofs_fill_inode_lazy(vi);
 682         if (err)
 683                 goto out;
 684
 685         if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
 686             !vi->z_tailextent_headlcn) {
 687                 map->m_la = 0;
 688                 map->m_llen = vi->i_size;
 689                 map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED |
 690                                 EROFS_MAP_FRAGMENT;
 691                 goto out;
 692         }
 693
 694         err = z_erofs_do_map_blocks(vi, map, flags);
 695 out:
 696         DBG_BUGON(err < 0 && err != -ENOMEM);
 697         return err;
 698 }