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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2018-2019 HUAWEI, Inc.
0004  *             https://www.huawei.com/
0005  */
0006 #include "internal.h"
0007 #include <asm/unaligned.h>
0008 #include <trace/events/erofs.h>
0009 
0010 static int z_erofs_do_map_blocks(struct inode *inode,
0011                  struct erofs_map_blocks *map,
0012                  int flags);
0013 
0014 int z_erofs_fill_inode(struct inode *inode)
0015 {
0016     struct erofs_inode *const vi = EROFS_I(inode);
0017     struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
0018 
0019     if (!erofs_sb_has_big_pcluster(sbi) &&
0020         !erofs_sb_has_ztailpacking(sbi) &&
0021         vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY) {
0022         vi->z_advise = 0;
0023         vi->z_algorithmtype[0] = 0;
0024         vi->z_algorithmtype[1] = 0;
0025         vi->z_logical_clusterbits = LOG_BLOCK_SIZE;
0026         set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
0027     }
0028     inode->i_mapping->a_ops = &z_erofs_aops;
0029     return 0;
0030 }
0031 
0032 static int z_erofs_fill_inode_lazy(struct inode *inode)
0033 {
0034     struct erofs_inode *const vi = EROFS_I(inode);
0035     struct super_block *const sb = inode->i_sb;
0036     int err, headnr;
0037     erofs_off_t pos;
0038     struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
0039     void *kaddr;
0040     struct z_erofs_map_header *h;
0041 
0042     if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) {
0043         /*
0044          * paired with smp_mb() at the end of the function to ensure
0045          * fields will only be observed after the bit is set.
0046          */
0047         smp_mb();
0048         return 0;
0049     }
0050 
0051     if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_Z_BIT, TASK_KILLABLE))
0052         return -ERESTARTSYS;
0053 
0054     err = 0;
0055     if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags))
0056         goto out_unlock;
0057 
0058     DBG_BUGON(!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
0059           !erofs_sb_has_ztailpacking(EROFS_SB(sb)) &&
0060           vi->datalayout == EROFS_INODE_FLAT_COMPRESSION_LEGACY);
0061 
0062     pos = ALIGN(iloc(EROFS_SB(sb), vi->nid) + vi->inode_isize +
0063             vi->xattr_isize, 8);
0064     kaddr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos),
0065                    EROFS_KMAP_ATOMIC);
0066     if (IS_ERR(kaddr)) {
0067         err = PTR_ERR(kaddr);
0068         goto out_unlock;
0069     }
0070 
0071     h = kaddr + erofs_blkoff(pos);
0072     vi->z_advise = le16_to_cpu(h->h_advise);
0073     vi->z_algorithmtype[0] = h->h_algorithmtype & 15;
0074     vi->z_algorithmtype[1] = h->h_algorithmtype >> 4;
0075 
0076     headnr = 0;
0077     if (vi->z_algorithmtype[0] >= Z_EROFS_COMPRESSION_MAX ||
0078         vi->z_algorithmtype[++headnr] >= Z_EROFS_COMPRESSION_MAX) {
0079         erofs_err(sb, "unknown HEAD%u format %u for nid %llu, please upgrade kernel",
0080               headnr + 1, vi->z_algorithmtype[headnr], vi->nid);
0081         err = -EOPNOTSUPP;
0082         goto unmap_done;
0083     }
0084 
0085     vi->z_logical_clusterbits = LOG_BLOCK_SIZE + (h->h_clusterbits & 7);
0086     if (!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
0087         vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
0088                 Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
0089         erofs_err(sb, "per-inode big pcluster without sb feature for nid %llu",
0090               vi->nid);
0091         err = -EFSCORRUPTED;
0092         goto unmap_done;
0093     }
0094     if (vi->datalayout == EROFS_INODE_FLAT_COMPRESSION &&
0095         !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
0096         !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2)) {
0097         erofs_err(sb, "big pcluster head1/2 of compact indexes should be consistent for nid %llu",
0098               vi->nid);
0099         err = -EFSCORRUPTED;
0100         goto unmap_done;
0101     }
0102 unmap_done:
0103     erofs_put_metabuf(&buf);
0104     if (err)
0105         goto out_unlock;
0106 
0107     if (vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER) {
0108         struct erofs_map_blocks map = {
0109             .buf = __EROFS_BUF_INITIALIZER
0110         };
0111 
0112         vi->z_idata_size = le16_to_cpu(h->h_idata_size);
0113         err = z_erofs_do_map_blocks(inode, &map,
0114                         EROFS_GET_BLOCKS_FINDTAIL);
0115         erofs_put_metabuf(&map.buf);
0116 
0117         if (!map.m_plen ||
0118             erofs_blkoff(map.m_pa) + map.m_plen > EROFS_BLKSIZ) {
0119             erofs_err(sb, "invalid tail-packing pclustersize %llu",
0120                   map.m_plen);
0121             err = -EFSCORRUPTED;
0122         }
0123         if (err < 0)
0124             goto out_unlock;
0125     }
0126     /* paired with smp_mb() at the beginning of the function */
0127     smp_mb();
0128     set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
0129 out_unlock:
0130     clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
0131     return err;
0132 }
0133 
0134 struct z_erofs_maprecorder {
0135     struct inode *inode;
0136     struct erofs_map_blocks *map;
0137     void *kaddr;
0138 
0139     unsigned long lcn;
0140     /* compression extent information gathered */
0141     u8  type, headtype;
0142     u16 clusterofs;
0143     u16 delta[2];
0144     erofs_blk_t pblk, compressedblks;
0145     erofs_off_t nextpackoff;
0146 };
0147 
0148 static int z_erofs_reload_indexes(struct z_erofs_maprecorder *m,
0149                   erofs_blk_t eblk)
0150 {
0151     struct super_block *const sb = m->inode->i_sb;
0152 
0153     m->kaddr = erofs_read_metabuf(&m->map->buf, sb, eblk,
0154                       EROFS_KMAP_ATOMIC);
0155     if (IS_ERR(m->kaddr))
0156         return PTR_ERR(m->kaddr);
0157     return 0;
0158 }
0159 
0160 static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m,
0161                      unsigned long lcn)
0162 {
0163     struct inode *const inode = m->inode;
0164     struct erofs_inode *const vi = EROFS_I(inode);
0165     const erofs_off_t ibase = iloc(EROFS_I_SB(inode), vi->nid);
0166     const erofs_off_t pos =
0167         Z_EROFS_VLE_LEGACY_INDEX_ALIGN(ibase + vi->inode_isize +
0168                            vi->xattr_isize) +
0169         lcn * sizeof(struct z_erofs_vle_decompressed_index);
0170     struct z_erofs_vle_decompressed_index *di;
0171     unsigned int advise, type;
0172     int err;
0173 
0174     err = z_erofs_reload_indexes(m, erofs_blknr(pos));
0175     if (err)
0176         return err;
0177 
0178     m->nextpackoff = pos + sizeof(struct z_erofs_vle_decompressed_index);
0179     m->lcn = lcn;
0180     di = m->kaddr + erofs_blkoff(pos);
0181 
0182     advise = le16_to_cpu(di->di_advise);
0183     type = (advise >> Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT) &
0184         ((1 << Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) - 1);
0185     switch (type) {
0186     case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
0187         m->clusterofs = 1 << vi->z_logical_clusterbits;
0188         m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
0189         if (m->delta[0] & Z_EROFS_VLE_DI_D0_CBLKCNT) {
0190             if (!(vi->z_advise & (Z_EROFS_ADVISE_BIG_PCLUSTER_1 |
0191                     Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
0192                 DBG_BUGON(1);
0193                 return -EFSCORRUPTED;
0194             }
0195             m->compressedblks = m->delta[0] &
0196                 ~Z_EROFS_VLE_DI_D0_CBLKCNT;
0197             m->delta[0] = 1;
0198         }
0199         m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
0200         break;
0201     case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
0202     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
0203     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
0204         m->clusterofs = le16_to_cpu(di->di_clusterofs);
0205         m->pblk = le32_to_cpu(di->di_u.blkaddr);
0206         break;
0207     default:
0208         DBG_BUGON(1);
0209         return -EOPNOTSUPP;
0210     }
0211     m->type = type;
0212     return 0;
0213 }
0214 
0215 static unsigned int decode_compactedbits(unsigned int lobits,
0216                      unsigned int lomask,
0217                      u8 *in, unsigned int pos, u8 *type)
0218 {
0219     const unsigned int v = get_unaligned_le32(in + pos / 8) >> (pos & 7);
0220     const unsigned int lo = v & lomask;
0221 
0222     *type = (v >> lobits) & 3;
0223     return lo;
0224 }
0225 
0226 static int get_compacted_la_distance(unsigned int lclusterbits,
0227                      unsigned int encodebits,
0228                      unsigned int vcnt, u8 *in, int i)
0229 {
0230     const unsigned int lomask = (1 << lclusterbits) - 1;
0231     unsigned int lo, d1 = 0;
0232     u8 type;
0233 
0234     DBG_BUGON(i >= vcnt);
0235 
0236     do {
0237         lo = decode_compactedbits(lclusterbits, lomask,
0238                       in, encodebits * i, &type);
0239 
0240         if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
0241             return d1;
0242         ++d1;
0243     } while (++i < vcnt);
0244 
0245     /* vcnt - 1 (Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) item */
0246     if (!(lo & Z_EROFS_VLE_DI_D0_CBLKCNT))
0247         d1 += lo - 1;
0248     return d1;
0249 }
0250 
0251 static int unpack_compacted_index(struct z_erofs_maprecorder *m,
0252                   unsigned int amortizedshift,
0253                   erofs_off_t pos, bool lookahead)
0254 {
0255     struct erofs_inode *const vi = EROFS_I(m->inode);
0256     const unsigned int lclusterbits = vi->z_logical_clusterbits;
0257     const unsigned int lomask = (1 << lclusterbits) - 1;
0258     unsigned int vcnt, base, lo, encodebits, nblk, eofs;
0259     int i;
0260     u8 *in, type;
0261     bool big_pcluster;
0262 
0263     if (1 << amortizedshift == 4)
0264         vcnt = 2;
0265     else if (1 << amortizedshift == 2 && lclusterbits == 12)
0266         vcnt = 16;
0267     else
0268         return -EOPNOTSUPP;
0269 
0270     /* it doesn't equal to round_up(..) */
0271     m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
0272              (vcnt << amortizedshift);
0273     big_pcluster = vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1;
0274     encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
0275     eofs = erofs_blkoff(pos);
0276     base = round_down(eofs, vcnt << amortizedshift);
0277     in = m->kaddr + base;
0278 
0279     i = (eofs - base) >> amortizedshift;
0280 
0281     lo = decode_compactedbits(lclusterbits, lomask,
0282                   in, encodebits * i, &type);
0283     m->type = type;
0284     if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
0285         m->clusterofs = 1 << lclusterbits;
0286 
0287         /* figure out lookahead_distance: delta[1] if needed */
0288         if (lookahead)
0289             m->delta[1] = get_compacted_la_distance(lclusterbits,
0290                         encodebits, vcnt, in, i);
0291         if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
0292             if (!big_pcluster) {
0293                 DBG_BUGON(1);
0294                 return -EFSCORRUPTED;
0295             }
0296             m->compressedblks = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
0297             m->delta[0] = 1;
0298             return 0;
0299         } else if (i + 1 != (int)vcnt) {
0300             m->delta[0] = lo;
0301             return 0;
0302         }
0303         /*
0304          * since the last lcluster in the pack is special,
0305          * of which lo saves delta[1] rather than delta[0].
0306          * Hence, get delta[0] by the previous lcluster indirectly.
0307          */
0308         lo = decode_compactedbits(lclusterbits, lomask,
0309                       in, encodebits * (i - 1), &type);
0310         if (type != Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
0311             lo = 0;
0312         else if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT)
0313             lo = 1;
0314         m->delta[0] = lo + 1;
0315         return 0;
0316     }
0317     m->clusterofs = lo;
0318     m->delta[0] = 0;
0319     /* figout out blkaddr (pblk) for HEAD lclusters */
0320     if (!big_pcluster) {
0321         nblk = 1;
0322         while (i > 0) {
0323             --i;
0324             lo = decode_compactedbits(lclusterbits, lomask,
0325                           in, encodebits * i, &type);
0326             if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD)
0327                 i -= lo;
0328 
0329             if (i >= 0)
0330                 ++nblk;
0331         }
0332     } else {
0333         nblk = 0;
0334         while (i > 0) {
0335             --i;
0336             lo = decode_compactedbits(lclusterbits, lomask,
0337                           in, encodebits * i, &type);
0338             if (type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
0339                 if (lo & Z_EROFS_VLE_DI_D0_CBLKCNT) {
0340                     --i;
0341                     nblk += lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;
0342                     continue;
0343                 }
0344                 /* bigpcluster shouldn't have plain d0 == 1 */
0345                 if (lo <= 1) {
0346                     DBG_BUGON(1);
0347                     return -EFSCORRUPTED;
0348                 }
0349                 i -= lo - 2;
0350                 continue;
0351             }
0352             ++nblk;
0353         }
0354     }
0355     in += (vcnt << amortizedshift) - sizeof(__le32);
0356     m->pblk = le32_to_cpu(*(__le32 *)in) + nblk;
0357     return 0;
0358 }
0359 
0360 static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m,
0361                         unsigned long lcn, bool lookahead)
0362 {
0363     struct inode *const inode = m->inode;
0364     struct erofs_inode *const vi = EROFS_I(inode);
0365     const unsigned int lclusterbits = vi->z_logical_clusterbits;
0366     const erofs_off_t ebase = ALIGN(iloc(EROFS_I_SB(inode), vi->nid) +
0367                     vi->inode_isize + vi->xattr_isize, 8) +
0368         sizeof(struct z_erofs_map_header);
0369     const unsigned int totalidx = DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
0370     unsigned int compacted_4b_initial, compacted_2b;
0371     unsigned int amortizedshift;
0372     erofs_off_t pos;
0373     int err;
0374 
0375     if (lclusterbits != 12)
0376         return -EOPNOTSUPP;
0377 
0378     if (lcn >= totalidx)
0379         return -EINVAL;
0380 
0381     m->lcn = lcn;
0382     /* used to align to 32-byte (compacted_2b) alignment */
0383     compacted_4b_initial = (32 - ebase % 32) / 4;
0384     if (compacted_4b_initial == 32 / 4)
0385         compacted_4b_initial = 0;
0386 
0387     if ((vi->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) &&
0388         compacted_4b_initial < totalidx)
0389         compacted_2b = rounddown(totalidx - compacted_4b_initial, 16);
0390     else
0391         compacted_2b = 0;
0392 
0393     pos = ebase;
0394     if (lcn < compacted_4b_initial) {
0395         amortizedshift = 2;
0396         goto out;
0397     }
0398     pos += compacted_4b_initial * 4;
0399     lcn -= compacted_4b_initial;
0400 
0401     if (lcn < compacted_2b) {
0402         amortizedshift = 1;
0403         goto out;
0404     }
0405     pos += compacted_2b * 2;
0406     lcn -= compacted_2b;
0407     amortizedshift = 2;
0408 out:
0409     pos += lcn * (1 << amortizedshift);
0410     err = z_erofs_reload_indexes(m, erofs_blknr(pos));
0411     if (err)
0412         return err;
0413     return unpack_compacted_index(m, amortizedshift, pos, lookahead);
0414 }
0415 
0416 static int z_erofs_load_cluster_from_disk(struct z_erofs_maprecorder *m,
0417                       unsigned int lcn, bool lookahead)
0418 {
0419     const unsigned int datamode = EROFS_I(m->inode)->datalayout;
0420 
0421     if (datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY)
0422         return legacy_load_cluster_from_disk(m, lcn);
0423 
0424     if (datamode == EROFS_INODE_FLAT_COMPRESSION)
0425         return compacted_load_cluster_from_disk(m, lcn, lookahead);
0426 
0427     return -EINVAL;
0428 }
0429 
0430 static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
0431                    unsigned int lookback_distance)
0432 {
0433     struct erofs_inode *const vi = EROFS_I(m->inode);
0434     const unsigned int lclusterbits = vi->z_logical_clusterbits;
0435 
0436     while (m->lcn >= lookback_distance) {
0437         unsigned long lcn = m->lcn - lookback_distance;
0438         int err;
0439 
0440         /* load extent head logical cluster if needed */
0441         err = z_erofs_load_cluster_from_disk(m, lcn, false);
0442         if (err)
0443             return err;
0444 
0445         switch (m->type) {
0446         case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
0447             if (!m->delta[0]) {
0448                 erofs_err(m->inode->i_sb,
0449                       "invalid lookback distance 0 @ nid %llu",
0450                       vi->nid);
0451                 DBG_BUGON(1);
0452                 return -EFSCORRUPTED;
0453             }
0454             lookback_distance = m->delta[0];
0455             continue;
0456         case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
0457         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
0458         case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
0459             m->headtype = m->type;
0460             m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
0461             return 0;
0462         default:
0463             erofs_err(m->inode->i_sb,
0464                   "unknown type %u @ lcn %lu of nid %llu",
0465                   m->type, lcn, vi->nid);
0466             DBG_BUGON(1);
0467             return -EOPNOTSUPP;
0468         }
0469     }
0470 
0471     erofs_err(m->inode->i_sb, "bogus lookback distance @ nid %llu",
0472           vi->nid);
0473     DBG_BUGON(1);
0474     return -EFSCORRUPTED;
0475 }
0476 
0477 static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
0478                         unsigned int initial_lcn)
0479 {
0480     struct erofs_inode *const vi = EROFS_I(m->inode);
0481     struct erofs_map_blocks *const map = m->map;
0482     const unsigned int lclusterbits = vi->z_logical_clusterbits;
0483     unsigned long lcn;
0484     int err;
0485 
0486     DBG_BUGON(m->type != Z_EROFS_VLE_CLUSTER_TYPE_PLAIN &&
0487           m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 &&
0488           m->type != Z_EROFS_VLE_CLUSTER_TYPE_HEAD2);
0489     DBG_BUGON(m->type != m->headtype);
0490 
0491     if (m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
0492         ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1) &&
0493          !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) ||
0494         ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) &&
0495          !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
0496         map->m_plen = 1ULL << lclusterbits;
0497         return 0;
0498     }
0499     lcn = m->lcn + 1;
0500     if (m->compressedblks)
0501         goto out;
0502 
0503     err = z_erofs_load_cluster_from_disk(m, lcn, false);
0504     if (err)
0505         return err;
0506 
0507     /*
0508      * If the 1st NONHEAD lcluster has already been handled initially w/o
0509      * valid compressedblks, which means at least it mustn't be CBLKCNT, or
0510      * an internal implemenatation error is detected.
0511      *
0512      * The following code can also handle it properly anyway, but let's
0513      * BUG_ON in the debugging mode only for developers to notice that.
0514      */
0515     DBG_BUGON(lcn == initial_lcn &&
0516           m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD);
0517 
0518     switch (m->type) {
0519     case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
0520     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
0521     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
0522         /*
0523          * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
0524          * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.
0525          */
0526         m->compressedblks = 1 << (lclusterbits - LOG_BLOCK_SIZE);
0527         break;
0528     case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
0529         if (m->delta[0] != 1)
0530             goto err_bonus_cblkcnt;
0531         if (m->compressedblks)
0532             break;
0533         fallthrough;
0534     default:
0535         erofs_err(m->inode->i_sb,
0536               "cannot found CBLKCNT @ lcn %lu of nid %llu",
0537               lcn, vi->nid);
0538         DBG_BUGON(1);
0539         return -EFSCORRUPTED;
0540     }
0541 out:
0542     map->m_plen = (u64)m->compressedblks << LOG_BLOCK_SIZE;
0543     return 0;
0544 err_bonus_cblkcnt:
0545     erofs_err(m->inode->i_sb,
0546           "bogus CBLKCNT @ lcn %lu of nid %llu",
0547           lcn, vi->nid);
0548     DBG_BUGON(1);
0549     return -EFSCORRUPTED;
0550 }
0551 
0552 static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
0553 {
0554     struct inode *inode = m->inode;
0555     struct erofs_inode *vi = EROFS_I(inode);
0556     struct erofs_map_blocks *map = m->map;
0557     unsigned int lclusterbits = vi->z_logical_clusterbits;
0558     u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
0559     int err;
0560 
0561     do {
0562         /* handle the last EOF pcluster (no next HEAD lcluster) */
0563         if ((lcn << lclusterbits) >= inode->i_size) {
0564             map->m_llen = inode->i_size - map->m_la;
0565             return 0;
0566         }
0567 
0568         err = z_erofs_load_cluster_from_disk(m, lcn, true);
0569         if (err)
0570             return err;
0571 
0572         if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD) {
0573             DBG_BUGON(!m->delta[1] &&
0574                   m->clusterofs != 1 << lclusterbits);
0575         } else if (m->type == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN ||
0576                m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD1 ||
0577                m->type == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
0578             /* go on until the next HEAD lcluster */
0579             if (lcn != headlcn)
0580                 break;
0581             m->delta[1] = 1;
0582         } else {
0583             erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of nid %llu",
0584                   m->type, lcn, vi->nid);
0585             DBG_BUGON(1);
0586             return -EOPNOTSUPP;
0587         }
0588         lcn += m->delta[1];
0589     } while (m->delta[1]);
0590 
0591     map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
0592     return 0;
0593 }
0594 
0595 static int z_erofs_do_map_blocks(struct inode *inode,
0596                  struct erofs_map_blocks *map,
0597                  int flags)
0598 {
0599     struct erofs_inode *const vi = EROFS_I(inode);
0600     bool ztailpacking = vi->z_advise & Z_EROFS_ADVISE_INLINE_PCLUSTER;
0601     struct z_erofs_maprecorder m = {
0602         .inode = inode,
0603         .map = map,
0604     };
0605     int err = 0;
0606     unsigned int lclusterbits, endoff;
0607     unsigned long initial_lcn;
0608     unsigned long long ofs, end;
0609 
0610     lclusterbits = vi->z_logical_clusterbits;
0611     ofs = flags & EROFS_GET_BLOCKS_FINDTAIL ? inode->i_size - 1 : map->m_la;
0612     initial_lcn = ofs >> lclusterbits;
0613     endoff = ofs & ((1 << lclusterbits) - 1);
0614 
0615     err = z_erofs_load_cluster_from_disk(&m, initial_lcn, false);
0616     if (err)
0617         goto unmap_out;
0618 
0619     if (ztailpacking && (flags & EROFS_GET_BLOCKS_FINDTAIL))
0620         vi->z_idataoff = m.nextpackoff;
0621 
0622     map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_ENCODED;
0623     end = (m.lcn + 1ULL) << lclusterbits;
0624 
0625     switch (m.type) {
0626     case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
0627     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD1:
0628     case Z_EROFS_VLE_CLUSTER_TYPE_HEAD2:
0629         if (endoff >= m.clusterofs) {
0630             m.headtype = m.type;
0631             map->m_la = (m.lcn << lclusterbits) | m.clusterofs;
0632             /*
0633              * For ztailpacking files, in order to inline data more
0634              * effectively, special EOF lclusters are now supported
0635              * which can have three parts at most.
0636              */
0637             if (ztailpacking && end > inode->i_size)
0638                 end = inode->i_size;
0639             break;
0640         }
0641         /* m.lcn should be >= 1 if endoff < m.clusterofs */
0642         if (!m.lcn) {
0643             erofs_err(inode->i_sb,
0644                   "invalid logical cluster 0 at nid %llu",
0645                   vi->nid);
0646             err = -EFSCORRUPTED;
0647             goto unmap_out;
0648         }
0649         end = (m.lcn << lclusterbits) | m.clusterofs;
0650         map->m_flags |= EROFS_MAP_FULL_MAPPED;
0651         m.delta[0] = 1;
0652         fallthrough;
0653     case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
0654         /* get the corresponding first chunk */
0655         err = z_erofs_extent_lookback(&m, m.delta[0]);
0656         if (err)
0657             goto unmap_out;
0658         break;
0659     default:
0660         erofs_err(inode->i_sb,
0661               "unknown type %u @ offset %llu of nid %llu",
0662               m.type, ofs, vi->nid);
0663         err = -EOPNOTSUPP;
0664         goto unmap_out;
0665     }
0666 
0667     map->m_llen = end - map->m_la;
0668 
0669     if (flags & EROFS_GET_BLOCKS_FINDTAIL)
0670         vi->z_tailextent_headlcn = m.lcn;
0671     if (ztailpacking && m.lcn == vi->z_tailextent_headlcn) {
0672         map->m_flags |= EROFS_MAP_META;
0673         map->m_pa = vi->z_idataoff;
0674         map->m_plen = vi->z_idata_size;
0675     } else {
0676         map->m_pa = blknr_to_addr(m.pblk);
0677         err = z_erofs_get_extent_compressedlen(&m, initial_lcn);
0678         if (err)
0679             goto out;
0680     }
0681 
0682     if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN)
0683         map->m_algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
0684     else if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2)
0685         map->m_algorithmformat = vi->z_algorithmtype[1];
0686     else
0687         map->m_algorithmformat = vi->z_algorithmtype[0];
0688 
0689     if ((flags & EROFS_GET_BLOCKS_FIEMAP) ||
0690         ((flags & EROFS_GET_BLOCKS_READMORE) &&
0691          map->m_algorithmformat == Z_EROFS_COMPRESSION_LZMA &&
0692          map->m_llen >= EROFS_BLKSIZ)) {
0693         err = z_erofs_get_extent_decompressedlen(&m);
0694         if (!err)
0695             map->m_flags |= EROFS_MAP_FULL_MAPPED;
0696     }
0697 unmap_out:
0698     erofs_unmap_metabuf(&m.map->buf);
0699 
0700 out:
0701     erofs_dbg("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
0702           __func__, map->m_la, map->m_pa,
0703           map->m_llen, map->m_plen, map->m_flags);
0704 
0705     return err;
0706 }
0707 
0708 int z_erofs_map_blocks_iter(struct inode *inode,
0709                 struct erofs_map_blocks *map,
0710                 int flags)
0711 {
0712     int err = 0;
0713 
0714     trace_z_erofs_map_blocks_iter_enter(inode, map, flags);
0715 
0716     /* when trying to read beyond EOF, leave it unmapped */
0717     if (map->m_la >= inode->i_size) {
0718         map->m_llen = map->m_la + 1 - inode->i_size;
0719         map->m_la = inode->i_size;
0720         map->m_flags = 0;
0721         goto out;
0722     }
0723 
0724     err = z_erofs_fill_inode_lazy(inode);
0725     if (err)
0726         goto out;
0727 
0728     err = z_erofs_do_map_blocks(inode, map, flags);
0729 out:
0730     trace_z_erofs_map_blocks_iter_exit(inode, map, flags, err);
0731 
0732     /* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
0733     DBG_BUGON(err < 0 && err != -ENOMEM);
0734     return err;
0735 }
0736 
0737 static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
0738                 loff_t length, unsigned int flags,
0739                 struct iomap *iomap, struct iomap *srcmap)
0740 {
0741     int ret;
0742     struct erofs_map_blocks map = { .m_la = offset };
0743 
0744     ret = z_erofs_map_blocks_iter(inode, &map, EROFS_GET_BLOCKS_FIEMAP);
0745     erofs_put_metabuf(&map.buf);
0746     if (ret < 0)
0747         return ret;
0748 
0749     iomap->bdev = inode->i_sb->s_bdev;
0750     iomap->offset = map.m_la;
0751     iomap->length = map.m_llen;
0752     if (map.m_flags & EROFS_MAP_MAPPED) {
0753         iomap->type = IOMAP_MAPPED;
0754         iomap->addr = map.m_pa;
0755     } else {
0756         iomap->type = IOMAP_HOLE;
0757         iomap->addr = IOMAP_NULL_ADDR;
0758         /*
0759          * No strict rule how to describe extents for post EOF, yet
0760          * we need do like below. Otherwise, iomap itself will get
0761          * into an endless loop on post EOF.
0762          */
0763         if (iomap->offset >= inode->i_size)
0764             iomap->length = length + map.m_la - offset;
0765     }
0766     iomap->flags = 0;
0767     return 0;
0768 }
0769 
0770 const struct iomap_ops z_erofs_iomap_report_ops = {
0771     .iomap_begin = z_erofs_iomap_begin_report,
0772 };
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