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