fs/erofs/zmap.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2018-2019 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  */
   6 #include "internal.h"
   7 #include <asm/unaligned.h>
   8 #include <trace/events/erofs.h>
   9
  10 static int z_erofs_do_map_blocks(struct inode *inode,
  11                                  struct erofs_map_blocks *map,
  12                                  int flags);
  13
  14 int z_erofs_fill_inode(struct inode *inode)
  15 {
  16         struct erofs_inode *const vi = EROFS_I(inode);
  17         struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
  18
  19         if (!erofs_sb_has_big_pcluster(sbi) &&
  20             !erofs_sb_has_ztailpacking(sbi) && !erofs_sb_has_fragments(sbi) &&
  21             vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
  22                 vi->z_advise = 0;
  23                 vi->z_algorithmtype[0] = 0;
  24                 vi->z_algorithmtype[1] = 0;
  25                 vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
  26                 set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
  27         }
  28         inode->i_mapping->a_ops = &z_erofs_aops;
  29         return 0;
  30 }
  31
  32 static int z_erofs_fill_inode_lazy(struct inode *inode)
  33 {
  34         struct erofs_inode *const vi = EROFS_I(inode);
  35         struct super_block *const sb = inode->i_sb;
  36         int err, headnr;
  37         erofs_off_t pos;
  38         struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
  39         void *kaddr;
  40         struct z_erofs_map_header *h;
  41
  42         if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) {
  43                 /*
  44                  * paired with smp_mb() at the end of the function to ensure
  45                  * fields will only be observed after the bit is set.
  46                  */
  47                 smp_mb();
  48                 return 0;
  49         }
  50
  51         if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE))
  52                 return -ERESTARTSYS;
  53
  54         err = 0;
  55         if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
  56                 goto out_unlock;
  57
  58         pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
  59                     vi->xattr_isize, 8);
  60         kaddr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos), EROFS_KMAP);
  61         if (IS_ERR(kaddr)) {
  62                 err = PTR_ERR(kaddr);
  63                 goto out_unlock;
  64         }
  65
  66         h = kaddr + erofs_blkoff(pos);
  67         /*
  68          * if the highest bit of the 8-byte map header is set, the whole file
  69          * is stored in the packed inode. The rest bits keeps z_fragmentoff.
  70          */
  71         if (h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT) {
  72                 vi->z_advise = Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
  73                 vi->z_fragmentoff = le64_to_cpu(*(__le64 *)h) ^ (1ULL << 63);
  74                 vi->z_tailextent_headlcn = 0;
  75                 goto done;
  76         }
  77         vi->z_advise = le16_to_cpu(h->h_advise);
  78         vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
  79         vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
  80
  81         headnr = 0;
  82         if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX ||
  83             vi->z_algorithmtype[++headnr] >= Z_EROFS_COMPRESSION_MAX) {
  84                 erofs_err(sb, "unknown HEAD%u format %u for nid %llu, please upgrade kernel",
  85                           headnr + 1, vi->z_algorithmtype[headnr], vi->nid);
  86                 err = -EOPNOTSUPP;
  87                 goto out_put_metabuf;
  88         }
  89
  90         vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7);
  91         if (!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
  92             vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
  93                             Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
  94                 erofs_err(sb, "per-inode big pcluster without sb feature for nid %llu",
  95                           vi->nid);
  96                 err = -EFSCORRUPTED;
  97                 goto out_put_metabuf;
  98         }
  99         if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION &&
 100             !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
 101             !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
 102                 erofs_err(sb, "big pcluster head1/2 of compact indexes should be consistent for nid %llu",
 103                           vi->nid);
 104                 err = -EFSCORRUPTED;
 105                 goto out_put_metabuf;
 106         }
 107
 108         if (vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER) {
 109                 struct erofs_map_blocks map = {
 110                         .buf = __EROFS_BUF_INITIALIZER
 111                 };
 112
 113                 vi->z_idata_size = le16_to_cpu(h->h_idata_size);
 114                 err = z_erofs_do_map_blocks(inode, &map,
 115                                             EROFS_GET_BLOCKS_FINDTAIL);
 116                 erofs_put_metabuf(&map.buf);
 117
 118                 if (!map.m_plen ||
 119                     erofs_blkoff(map.m_pa) + map.m_plen > EROFS_BLKSIZ) {
 120                         erofs_err(sb, "invalid tail-packing pclustersize %llu",
 121                                   map.m_plen);
 122                         err = -EFSCORRUPTED;
 123                 }
 124                 if (err < 0)
 125                         goto out_put_metabuf;
 126         }
 127
 128         if (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER &&
 129             !(h->h_clusterbits >> Z_EROFS_FRAGMENT_INODE_BIT)) {
 130                 struct erofs_map_blocks map = {
 131                         .buf = __EROFS_BUF_INITIALIZER
 132                 };
 133
 134                 vi->z_fragmentoff = le32_to_cpu(h->h_fragmentoff);
 135                 err = z_erofs_do_map_blocks(inode, &map,
 136                                             EROFS_GET_BLOCKS_FINDTAIL);
 137                 erofs_put_metabuf(&map.buf);
 138                 if (err < 0)
 139                         goto out_put_metabuf;
 140         }
 141 done:
 142         /* paired with smp_mb() at the beginning of the function */
 143         smp_mb();
 144         set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
 145 out_put_metabuf:
 146         erofs_put_metabuf(&buf);
 147 out_unlock:
 148         clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
 149         return err;
 150 }
 151
 152 struct z_erofs_maprecorder {
 153         struct inode *inode;
 154         struct erofs_map_blocks *map;
 155         void *kaddr;
 156
 157         unsigned long lcn;
 158         /* compression extent information gathered */
 159         u8  type, headtype;
 160         u16 clusterofs;
 161         u16 delta[2];
 162         erofs_blk_t pblk, compressedblks;
 163         erofs_off_t nextpackoff;
 164         bool partialref;
 165 };
 166
 167 static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 168                                          unsigned long lcn)
 169 {
 170         struct inode *const inode = m->inode;
 171         struct erofs_inode *const vi = EROFS_I(inode);
 172         const erofs_off_t ibase = iloc(EROFS_I_SB(inode), vi->nid);
 173         const erofs_off_t pos =
 174                 Z_EROFS_VLE_LEGACY_INDEX_ALIGN(ibase + vi->inode_isize +
 175                                                vi->xattr_isize) +
 176                 lcn * sizeof(struct z_erofs_vle_decompressed_index);
 177         struct z_erofs_vle_decompressed_index *di;
 178         unsigned int advise, type;
 179
 180         m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
 181                                       erofs_blknr(pos), EROFS_KMAP_ATOMIC);
 182         if (IS_ERR(m->kaddr))
 183                 return PTR_ERR(m->kaddr);
 184
 185         m->nextpackoff = pos + sizeof(struct z_erofs_vle_decompressed_index);
 186         m->lcn = lcn;
 187         di = m->kaddr + erofs_blkoff(pos);
 188
 189         advise = le16_to_cpu(di->di_advise);
 190         type = (advise >> Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT) &
 191                 ((1 << Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) - 1);
 192         switch (type) {
 193         case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 194                 m->clusterofs = 1 << vi->z_logical_clusterbits;
 195                 m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
 196                 if (m->delta[0] & Z_EROFS_VLE_DI_D0_CBLKCNT) {
 197                         if (!(vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
 198                                         Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
 199                                 DBG_BUGON(1);
 200                                 return -EFSCORRUPTED;
 201                         }
 202                         m->compressedblks = m->delta[0] &
 203                                 ~Z_EROFS_VLE_DI_D0_CBLKCNT;
 204                         m->delta[0] = 1;
 205                 }
 206                 m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
 207                 break;
 208         case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 209         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
 210         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
 211                 if (advise & Z_EROFS_VLE_DI_PARTIAL_REF)
 212                         m->partialref = true;
 213                 m->clusterofs = le16_to_cpu(di->di_clusterofs);
 214                 m->pblk = le32_to_cpu(di->di_u.blkaddr);
 215                 break;
 216         default:
 217                 DBG_BUGON(1);
 218                 return -EOPNOTSUPP;
 219         }
 220         m->type = type;
 221         return 0;
 222 }
 223
 224 static unsigned int decode_compactedbits(unsigned int lobits,
 225                                          unsigned int lomask,
 226                                          u8 *in, unsigned int pos, u8 *type)
 227 {
 228         const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
 229         const unsigned int lo = v & lomask;
 230
 231         *type = (v >> lobits) & 3;
 232         return lo;
 233 }
 234
 235 static int get_compacted_la_distance(unsigned int lclusterbits,
 236                                      unsigned int encodebits,
 237                                      unsigned int vcnt, u8 *in, int i)
 238 {
 239         const unsigned int lomask = (1 << lclusterbits) - 1;
 240         unsigned int lo, d1 = 0;
 241         u8 type;
 242
 243         DBG_BUGON(i >= vcnt);
 244
 245         do {
 246                 lo = decode_compactedbits(lclusterbits, lomask,
 247                                           in, encodebits * i, &type);
 248
 249                 if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
 250                         return d1;
 251                 ++d1;
 252         } while (++i < vcnt);
 253
 254         /* vcnt - 1 (Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) item */
 255         if (!(lo & Z_EROFS_VLE_DI_D0_CBLKCNT))
 256                 d1 += lo - 1;
 257         return d1;
 258 }
 259
 260 static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 261                                   unsigned int amortizedshift,
 262                                   erofs_off_t pos, bool lookahead)
 263 {
 264         struct erofs_inode *const vi = EROFS_I(m->inode);
 265         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 266         const unsigned int lomask = (1 << lclusterbits) - 1;
 267         unsigned int vcnt, base, lo, encodebits, nblk, eofs;
 268         int i;
 269         u8 *in, type;
 270         bool big_pcluster;
 271
 272         if (1 << amortizedshift == 4)
 273                 vcnt = 2;
 274         else if (1 << amortizedshift == 2 && lclusterbits == 12)
 275                 vcnt = 16;
 276         else
 277                 return -EOPNOTSUPP;
 278
 279         /* it doesn't equal to round_up(..) */
 280         m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
 281                          (vcnt << amortizedshift);
 282         big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
 283         encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
 284         eofs = erofs_blkoff(pos);
 285         base = round_down(eofs, vcnt << amortizedshift);
 286         in = m->kaddr + base;
 287
 288         i = (eofs - base) >> amortizedshift;
 289
 290         lo = decode_compactedbits(lclusterbits, lomask,
 291                                   in, encodebits * i, &type);
 292         m->type = type;
 293         if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
 294                 m->clusterofs = 1 << lclusterbits;
 295
 296                 /* figure out lookahead_distance: delta[1] if needed */
 297                 if (lookahead)
 298                         m->delta[1] = get_compacted_la_distance(lclusterbits,
 299                                                 encodebits, vcnt, in, i);
 300                 if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
 301                         if (!big_pcluster) {
 302                                 DBG_BUGON(1);
 303                                 return -EFSCORRUPTED;
 304                         }
 305                         m->compressedblks = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
 306                         m->delta[0] = 1;
 307                         return 0;
 308                 } else if (i + 1 != (int)vcnt) {
 309                         m->delta[0] = lo;
 310                         return 0;
 311                 }
 312                 /*
 313                  * since the last lcluster in the pack is special,
 314                  * of which lo saves delta[1] rather than delta[0].
 315                  * Hence, get delta[0] by the previous lcluster indirectly.
 316                  */
 317                 lo = decode_compactedbits(lclusterbits, lomask,
 318                                           in, encodebits * (i - 1), &type);
 319                 if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
 320                         lo = 0;
 321                 else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT)
 322                         lo = 1;
 323                 m->delta[0] = lo + 1;
 324                 return 0;
 325         }
 326         m->clusterofs = lo;
 327         m->delta[0] = 0;
 328         /* figout out blkaddr (pblk) for HEAD lclusters */
 329         if (!big_pcluster) {
 330                 nblk = 1;
 331                 while (i > 0) {
 332                         --i;
 333                         lo = decode_compactedbits(lclusterbits, lomask,
 334                                                   in, encodebits * i, &type);
 335                         if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
 336                                 i -= lo;
 337
 338                         if (i >= 0)
 339                                 ++nblk;
 340                 }
 341         } else {
 342                 nblk = 0;
 343                 while (i > 0) {
 344                         --i;
 345                         lo = decode_compactedbits(lclusterbits, lomask,
 346                                                   in, encodebits * i, &type);
 347                         if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
 348                                 if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
 349                                         --i;
 350                                         nblk += lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
 351                                         continue;
 352                                 }
 353                                 /* bigpcluster shouldn't have plain d0 == 1 */
 354                                 if (lo <= 1) {
 355                                         DBG_BUGON(1);
 356                                         return -EFSCORRUPTED;
 357                                 }
 358                                 i -= lo - 2;
 359                                 continue;
 360                         }
 361                         ++nblk;
 362                 }
 363         }
 364         in += (vcnt << amortizedshift) - sizeof(__le32);
 365         m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
 366         return 0;
 367 }
 368
 369 static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 370                                             unsigned long lcn, bool lookahead)
 371 {
 372         struct inode *const inode = m->inode;
 373         struct erofs_inode *const vi = EROFS_I(inode);
 374         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 375         const erofs_off_t ebase = ALIGN(iloc(EROFS_I_SB(inode), vi->nid) +
 376                                         vi->inode_isize + vi->xattr_isize, 8) +
 377                 sizeof(struct z_erofs_map_header);
 378         const unsigned int totalidx = DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
 379         unsigned int compacted_4b_initial, compacted_2b;
 380         unsigned int amortizedshift;
 381         erofs_off_t pos;
 382
 383         if (lclusterbits != 12)
 384                 return -EOPNOTSUPP;
 385
 386         if (lcn >= totalidx)
 387                 return -EINVAL;
 388
 389         m->lcn = lcn;
 390         /* used to align to 32-byte (compacted_2b) alignment */
 391         compacted_4b_initial = (32 - ebase % 32) / 4;
 392         if (compacted_4b_initial == 32 / 4)
 393                 compacted_4b_initial = 0;
 394
 395         if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&
 396             compacted_4b_initial < totalidx)
 397                 compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
 398         else
 399                 compacted_2b = 0;
 400
 401         pos = ebase;
 402         if (lcn < compacted_4b_initial) {
 403                 amortizedshift = 2;
 404                 goto out;
 405         }
 406         pos += compacted_4b_initial * 4;
 407         lcn -= compacted_4b_initial;
 408
 409         if (lcn < compacted_2b) {
 410                 amortizedshift = 1;
 411                 goto out;
 412         }
 413         pos += compacted_2b * 2;
 414         lcn -= compacted_2b;
 415         amortizedshift = 2;
 416 out:
 417         pos += lcn * (1 << amortizedshift);
 418         m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
 419                                       erofs_blknr(pos), EROFS_KMAP_ATOMIC);
 420         if (IS_ERR(m->kaddr))
 421                 return PTR_ERR(m->kaddr);
 422         return unpack_compacted_index(m, amortizedshift, pos, lookahead);
 423 }
 424
 425 static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
 426                                           unsigned int lcn, bool lookahead)
 427 {
 428         const unsigned int datamode = EROFS_I(m->inode)->datalayout;
 429
 430         if (datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
 431                 return legacy_load_cluster_from_disk(m, lcn);
 432
 433         if (datamode == EROFS_INODE_FLAT_COMPRESSION)
 434                 return compacted_load_cluster_from_disk(m, lcn, lookahead);
 435
 436         return -EINVAL;
 437 }
 438
 439 static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 440                                    unsigned int lookback_distance)
 441 {
 442         struct erofs_inode *const vi = EROFS_I(m->inode);
 443         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 444
 445         while (m->lcn >= lookback_distance) {
 446                 unsigned long lcn = m->lcn - lookback_distance;
 447                 int err;
 448
 449                 /* load extent head logical cluster if needed */
 450                 err = z_erofs_load_cluster_from_disk(m, lcn, false);
 451                 if (err)
 452                         return err;
 453
 454                 switch (m->type) {
 455                 case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 456                         if (!m->delta[0]) {
 457                                 erofs_err(m->inode->i_sb,
 458                                           "invalid lookback distance 0 @ nid %llu",
 459                                           vi->nid);
 460                                 DBG_BUGON(1);
 461                                 return -EFSCORRUPTED;
 462                         }
 463                         lookback_distance = m->delta[0];
 464                         continue;
 465                 case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 466                 case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
 467                 case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
 468                         m->headtype = m->type;
 469                         m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
 470                         return 0;
 471                 default:
 472                         erofs_err(m->inode->i_sb,
 473                                   "unknown type %u @ lcn %lu of nid %llu",
 474                                   m->type, lcn, vi->nid);
 475                         DBG_BUGON(1);
 476                         return -EOPNOTSUPP;
 477                 }
 478         }
 479
 480         erofs_err(m->inode->i_sb, "bogus lookback distance @ nid %llu",
 481                   vi->nid);
 482         DBG_BUGON(1);
 483         return -EFSCORRUPTED;
 484 }
 485
 486 static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 487                                             unsigned int initial_lcn)
 488 {
 489         struct erofs_inode *const vi = EROFS_I(m->inode);
 490         struct erofs_map_blocks *const map = m->map;
 491         const unsigned int lclusterbits = vi->z_logical_clusterbits;
 492         unsigned long lcn;
 493         int err;
 494
 495         DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
 496                   m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 &&
 497                   m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD2);
 498         DBG_BUGON(m->type != m->headtype);
 499
 500         if (m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
 501             ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1) &&
 502              !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) ||
 503             ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) &&
 504              !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
 505                 map->m_plen = 1ULL << lclusterbits;
 506                 return 0;
 507         }
 508         lcn = m->lcn + 1;
 509         if (m->compressedblks)
 510                 goto out;
 511
 512         err = z_erofs_load_cluster_from_disk(m, lcn, false);
 513         if (err)
 514                 return err;
 515
 516         /*
 517          * If the 1st NONHEAD lcluster has already been handled initially w/o
 518          * valid compressedblks, which means at least it mustn't be CBLKCNT, or
 519          * an internal implemenatation error is detected.
 520          *
 521          * The following code can also handle it properly anyway, but let's
 522          * BUG_ON in the debugging mode only for developers to notice that.
 523          */
 524         DBG_BUGON(lcn == initial_lcn &&
 525                   m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD);
 526
 527         switch (m->type) {
 528         case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 529         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
 530         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
 531                 /*
 532                  * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
 533                  * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
 534                  */
 535                 m->compressedblks = 1 << (lclusterbits - LOG_BLOCK_SIZE);
 536                 break;
 537         case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 538                 if (m->delta[0] != 1)
 539                         goto err_bonus_cblkcnt;
 540                 if (m->compressedblks)
 541                         break;
 542                 fallthrough;
 543         default:
 544                 erofs_err(m->inode->i_sb,
 545                           "cannot found CBLKCNT @ lcn %lu of nid %llu",
 546                           lcn, vi->nid);
 547                 DBG_BUGON(1);
 548                 return -EFSCORRUPTED;
 549         }
 550 out:
 551         map->m_plen = (u64)m->compressedblks << LOG_BLOCK_SIZE;
 552         return 0;
 553 err_bonus_cblkcnt:
 554         erofs_err(m->inode->i_sb,
 555                   "bogus CBLKCNT @ lcn %lu of nid %llu",
 556                   lcn, vi->nid);
 557         DBG_BUGON(1);
 558         return -EFSCORRUPTED;
 559 }
 560
 561 static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 562 {
 563         struct inode *inode = m->inode;
 564         struct erofs_inode *vi = EROFS_I(inode);
 565         struct erofs_map_blocks *map = m->map;
 566         unsigned int lclusterbits = vi->z_logical_clusterbits;
 567         u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
 568         int err;
 569
 570         do {
 571                 /* handle the last EOF pcluster (no next HEAD lcluster) */
 572                 if ((lcn << lclusterbits) >= inode->i_size) {
 573                         map->m_llen = inode->i_size - map->m_la;
 574                         return 0;
 575                 }
 576
 577                 err = z_erofs_load_cluster_from_disk(m, lcn, true);
 578                 if (err)
 579                         return err;
 580
 581                 if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
 582                         DBG_BUGON(!m->delta[1] &&
 583                                   m->clusterofs != 1 << lclusterbits);
 584                 } else if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
 585                            m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 ||
 586                            m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
 587                         /* go on until the next HEAD lcluster */
 588                         if (lcn != headlcn)
 589                                 break;
 590                         m->delta[1] = 1;
 591                 } else {
 592                         erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of nid %llu",
 593                                   m->type, lcn, vi->nid);
 594                         DBG_BUGON(1);
 595                         return -EOPNOTSUPP;
 596                 }
 597                 lcn += m->delta[1];
 598         } while (m->delta[1]);
 599
 600         map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
 601         return 0;
 602 }
 603
 604 static int z_erofs_do_map_blocks(struct inode *inode,
 605                                  struct erofs_map_blocks *map,
 606                                  int flags)
 607 {
 608         struct erofs_inode *const vi = EROFS_I(inode);
 609         bool ztailpacking = vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER;
 610         bool fragment = vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER;
 611         struct z_erofs_maprecorder m = {
 612                 .inode = inode,
 613                 .map = map,
 614         };
 615         int err = 0;
 616         unsigned int lclusterbits, endoff;
 617         unsigned long initial_lcn;
 618         unsigned long long ofs, end;
 619
 620         lclusterbits = vi->z_logical_clusterbits;
 621         ofs = flags & EROFS_GET_BLOCKS_FINDTAIL ? inode->i_size - 1 : map->m_la;
 622         initial_lcn = ofs >> lclusterbits;
 623         endoff = ofs & ((1 << lclusterbits) - 1);
 624
 625         err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
 626         if (err)
 627                 goto unmap_out;
 628
 629         if (ztailpacking && (flags & EROFS_GET_BLOCKS_FINDTAIL))
 630                 vi->z_idataoff = m.nextpackoff;
 631
 632         map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
 633         end = (m.lcn + 1ULL) << lclusterbits;
 634
 635         switch (m.type) {
 636         case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 637         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
 638         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
 639                 if (endoff >= m.clusterofs) {
 640                         m.headtype = m.type;
 641                         map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
 642                         /*
 643                          * For ztailpacking files, in order to inline data more
 644                          * effectively, special EOF lclusters are now supported
 645                          * which can have three parts at most.
 646                          */
 647                         if (ztailpacking && end > inode->i_size)
 648                                 end = inode->i_size;
 649                         break;
 650                 }
 651                 /* m.lcn should be >= 1 if endoff < m.clusterofs */
 652                 if (!m.lcn) {
 653                         erofs_err(inode->i_sb,
 654                                   "invalid logical cluster 0 at nid %llu",
 655                                   vi->nid);
 656                         err = -EFSCORRUPTED;
 657                         goto unmap_out;
 658                 }
 659                 end = (m.lcn << lclusterbits) | m.clusterofs;
 660                 map->m_flags |= EROFS_MAP_FULL_MAPPED;
 661                 m.delta[0] = 1;
 662                 fallthrough;
 663         case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
 664                 /* get the corresponding first chunk */
 665                 err = z_erofs_extent_lookback(&m, m.delta[0]);
 666                 if (err)
 667                         goto unmap_out;
 668                 break;
 669         default:
 670                 erofs_err(inode->i_sb,
 671                           "unknown type %u @ offset %llu of nid %llu",
 672                           m.type, ofs, vi->nid);
 673                 err = -EOPNOTSUPP;
 674                 goto unmap_out;
 675         }
 676         if (m.partialref)
 677                 map->m_flags |= EROFS_MAP_PARTIAL_REF;
 678         map->m_llen = end - map->m_la;
 679
 680         if (flags & EROFS_GET_BLOCKS_FINDTAIL) {
 681                 vi->z_tailextent_headlcn = m.lcn;
 682                 /* for non-compact indexes, fragmentoff is 64 bits */
 683                 if (fragment &&
 684                     vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
 685                         vi->z_fragmentoff |= (u64)m.pblk << 32;
 686         }
 687         if (ztailpacking && m.lcn == vi->z_tailextent_headlcn) {
 688                 map->m_flags |= EROFS_MAP_META;
 689                 map->m_pa = vi->z_idataoff;
 690                 map->m_plen = vi->z_idata_size;
 691         } else if (fragment && m.lcn == vi->z_tailextent_headlcn) {
 692                 map->m_flags |= EROFS_MAP_FRAGMENT;
 693         } else {
 694                 map->m_pa = blknr_to_addr(m.pblk);
 695                 err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
 696                 if (err)
 697                         goto unmap_out;
 698         }
 699
 700         if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN) {
 701                 if (map->m_llen > map->m_plen) {
 702                         DBG_BUGON(1);
 703                         err = -EFSCORRUPTED;
 704                         goto unmap_out;
 705                 }
 706                 if (vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER)
 707                         map->m_algorithmformat =
 708                                 Z_EROFS_COMPRESSION_INTERLACED;
 709                 else
 710                         map->m_algorithmformat =
 711                                 Z_EROFS_COMPRESSION_SHIFTED;
 712         } else if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
 713                 map->m_algorithmformat = vi->z_algorithmtype[1];
 714         } else {
 715                 map->m_algorithmformat = vi->z_algorithmtype[0];
 716         }
 717
 718         if ((flags & EROFS_GET_BLOCKS_FIEMAP) ||
 719             ((flags & EROFS_GET_BLOCKS_READMORE) &&
 720              map->m_algorithmformat == Z_EROFS_COMPRESSION_LZMA &&
 721              map->m_llen >= EROFS_BLKSIZ)) {
 722                 err = z_erofs_get_extent_decompressedlen(&m);
 723                 if (!err)
 724                         map->m_flags |= EROFS_MAP_FULL_MAPPED;
 725         }
 726
 727 unmap_out:
 728         erofs_unmap_metabuf(&m.map->buf);
 729         erofs_dbg("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
 730                   __func__, map->m_la, map->m_pa,
 731                   map->m_llen, map->m_plen, map->m_flags);
 732         return err;
 733 }
 734
 735 int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
 736                             int flags)
 737 {
 738         struct erofs_inode *const vi = EROFS_I(inode);
 739         int err = 0;
 740
 741         trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
 742
 743         /* when trying to read beyond EOF, leave it unmapped */
 744         if (map->m_la >= inode->i_size) {
 745                 map->m_llen = map->m_la + 1 - inode->i_size;
 746                 map->m_la = inode->i_size;
 747                 map->m_flags = 0;
 748                 goto out;
 749         }
 750
 751         err = z_erofs_fill_inode_lazy(inode);
 752         if (err)
 753                 goto out;
 754
 755         if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
 756             !vi->z_tailextent_headlcn) {
 757                 map->m_la = 0;
 758                 map->m_llen = inode->i_size;
 759                 map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED |
 760                                 EROFS_MAP_FRAGMENT;
 761                 goto out;
 762         }
 763
 764         err = z_erofs_do_map_blocks(inode, map, flags);
 765 out:
 766         trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
 767
 768         /* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
 769         DBG_BUGON(err < 0 && err != -ENOMEM);
 770         return err;
 771 }
 772
 773 static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
 774                                 loff_t length, unsigned int flags,
 775                                 struct iomap *iomap, struct iomap *srcmap)
 776 {
 777         int ret;
 778         struct erofs_map_blocks map = { .m_la = offset };
 779
 780         ret = z_erofs_map_blocks_iter(inode, &map, EROFS_GET_BLOCKS_FIEMAP);
 781         erofs_put_metabuf(&map.buf);
 782         if (ret < 0)
 783                 return ret;
 784
 785         iomap->bdev = inode->i_sb->s_bdev;
 786         iomap->offset = map.m_la;
 787         iomap->length = map.m_llen;
 788         if (map.m_flags & EROFS_MAP_MAPPED) {
 789                 iomap->type = IOMAP_MAPPED;
 790                 iomap->addr = map.m_flags & EROFS_MAP_FRAGMENT ?
 791                               IOMAP_NULL_ADDR : map.m_pa;
 792         } else {
 793                 iomap->type = IOMAP_HOLE;
 794                 iomap->addr = IOMAP_NULL_ADDR;
 795                 /*
 796                  * No strict rule on how to describe extents for post EOF, yet
 797                  * we need to do like below. Otherwise, iomap itself will get
 798                  * into an endless loop on post EOF.
 799                  *
 800                  * Calculate the effective offset by subtracting extent start
 801                  * (map.m_la) from the requested offset, and add it to length.
 802                  * (NB: offset >= map.m_la always)
 803                  */
 804                 if (iomap->offset >= inode->i_size)
 805                         iomap->length = length + offset - map.m_la;
 806         }
 807         iomap->flags = 0;
 808         return 0;
 809 }
 810
 811 const struct iomap_ops z_erofs_iomap_report_ops = {
 812         .iomap_begin = z_erofs_iomap_begin_report,
 813 };