fs/erofs/decompressor.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2019 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  * Copyright (C) 2024 Alibaba Cloud
   6  */
   7 #include "compress.h"
   8 #include <linux/lz4.h>
   9
  10 #define LZ4_MAX_DISTANCE_PAGES  (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
  11
  12 struct z_erofs_lz4_decompress_ctx {
  13         struct z_erofs_decompress_req *rq;
  14         /* # of encoded, decoded pages */
  15         unsigned int inpages, outpages;
  16         /* decoded block total length (used for in-place decompression) */
  17         unsigned int oend;
  18 };
  19
  20 static int z_erofs_load_lz4_config(struct super_block *sb,
  21                             struct erofs_super_block *dsb, void *data, int size)
  22 {
  23         struct erofs_sb_info *sbi = EROFS_SB(sb);
  24         struct z_erofs_lz4_cfgs *lz4 = data;
  25         u16 distance;
  26
  27         if (lz4) {
  28                 if (size < sizeof(struct z_erofs_lz4_cfgs)) {
  29                         erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
  30                         return -EINVAL;
  31                 }
  32                 distance = le16_to_cpu(lz4->max_distance);
  33
  34                 sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
  35                 if (!sbi->lz4.max_pclusterblks) {
  36                         sbi->lz4.max_pclusterblks = 1;  /* reserved case */
  37                 } else if (sbi->lz4.max_pclusterblks >
  38                            erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) {
  39                         erofs_err(sb, "too large lz4 pclusterblks %u",
  40                                   sbi->lz4.max_pclusterblks);
  41                         return -EINVAL;
  42                 }
  43         } else {
  44                 distance = le16_to_cpu(dsb->u1.lz4_max_distance);
  45                 sbi->lz4.max_pclusterblks = 1;
  46         }
  47
  48         sbi->lz4.max_distance_pages = distance ?
  49                                         DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
  50                                         LZ4_MAX_DISTANCE_PAGES;
  51         return z_erofs_gbuf_growsize(sbi->lz4.max_pclusterblks);
  52 }
  53
  54 /*
  55  * Fill all gaps with bounce pages if it's a sparse page list. Also check if
  56  * all physical pages are consecutive, which can be seen for moderate CR.
  57  */
  58 static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
  59                                         struct page **pagepool)
  60 {
  61         struct z_erofs_decompress_req *rq = ctx->rq;
  62         struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
  63         unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
  64                                            BITS_PER_LONG)] = { 0 };
  65         unsigned int lz4_max_distance_pages =
  66                                 EROFS_SB(rq->sb)->lz4.max_distance_pages;
  67         void *kaddr = NULL;
  68         unsigned int i, j, top;
  69
  70         top = 0;
  71         for (i = j = 0; i < ctx->outpages; ++i, ++j) {
  72                 struct page *const page = rq->out[i];
  73                 struct page *victim;
  74
  75                 if (j >= lz4_max_distance_pages)
  76                         j = 0;
  77
  78                 /* 'valid' bounced can only be tested after a complete round */
  79                 if (!rq->fillgaps && test_bit(j, bounced)) {
  80                         DBG_BUGON(i < lz4_max_distance_pages);
  81                         DBG_BUGON(top >= lz4_max_distance_pages);
  82                         availables[top++] = rq->out[i - lz4_max_distance_pages];
  83                 }
  84
  85                 if (page) {
  86                         __clear_bit(j, bounced);
  87                         if (!PageHighMem(page)) {
  88                                 if (!i) {
  89                                         kaddr = page_address(page);
  90                                         continue;
  91                                 }
  92                                 if (kaddr &&
  93                                     kaddr + PAGE_SIZE == page_address(page)) {
  94                                         kaddr += PAGE_SIZE;
  95                                         continue;
  96                                 }
  97                         }
  98                         kaddr = NULL;
  99                         continue;
 100                 }
 101                 kaddr = NULL;
 102                 __set_bit(j, bounced);
 103
 104                 if (top) {
 105                         victim = availables[--top];
 106                 } else {
 107                         victim = __erofs_allocpage(pagepool, rq->gfp, true);
 108                         if (!victim)
 109                                 return -ENOMEM;
 110                         set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
 111                 }
 112                 rq->out[i] = victim;
 113         }
 114         return kaddr ? 1 : 0;
 115 }
 116
 117 static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
 118                         void *inpage, void *out, unsigned int *inputmargin,
 119                         int *maptype, bool may_inplace)
 120 {
 121         struct z_erofs_decompress_req *rq = ctx->rq;
 122         unsigned int omargin, total, i;
 123         struct page **in;
 124         void *src, *tmp;
 125
 126         if (rq->inplace_io) {
 127                 omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
 128                 if (rq->partial_decoding || !may_inplace ||
 129                     omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
 130                         goto docopy;
 131
 132                 for (i = 0; i < ctx->inpages; ++i)
 133                         if (rq->out[ctx->outpages - ctx->inpages + i] !=
 134                             rq->in[i])
 135                                 goto docopy;
 136                 kunmap_local(inpage);
 137                 *maptype = 3;
 138                 return out + ((ctx->outpages - ctx->inpages) << PAGE_SHIFT);
 139         }
 140
 141         if (ctx->inpages <= 1) {
 142                 *maptype = 0;
 143                 return inpage;
 144         }
 145         kunmap_local(inpage);
 146         src = erofs_vm_map_ram(rq->in, ctx->inpages);
 147         if (!src)
 148                 return ERR_PTR(-ENOMEM);
 149         *maptype = 1;
 150         return src;
 151
 152 docopy:
 153         /* Or copy compressed data which can be overlapped to per-CPU buffer */
 154         in = rq->in;
 155         src = z_erofs_get_gbuf(ctx->inpages);
 156         if (!src) {
 157                 DBG_BUGON(1);
 158                 kunmap_local(inpage);
 159                 return ERR_PTR(-EFAULT);
 160         }
 161
 162         tmp = src;
 163         total = rq->inputsize;
 164         while (total) {
 165                 unsigned int page_copycnt =
 166                         min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
 167
 168                 if (!inpage)
 169                         inpage = kmap_local_page(*in);
 170                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 171                 kunmap_local(inpage);
 172                 inpage = NULL;
 173                 tmp += page_copycnt;
 174                 total -= page_copycnt;
 175                 ++in;
 176                 *inputmargin = 0;
 177         }
 178         *maptype = 2;
 179         return src;
 180 }
 181
 182 /*
 183  * Get the exact inputsize with zero_padding feature.
 184  *  - For LZ4, it should work if zero_padding feature is on (5.3+);
 185  *  - For MicroLZMA, it'd be enabled all the time.
 186  */
 187 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 188                          unsigned int padbufsize)
 189 {
 190         const char *padend;
 191
 192         padend = memchr_inv(padbuf, 0, padbufsize);
 193         if (!padend)
 194                 return -EFSCORRUPTED;
 195         rq->inputsize -= padend - padbuf;
 196         rq->pageofs_in += padend - padbuf;
 197         return 0;
 198 }
 199
 200 static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
 201                                       u8 *dst)
 202 {
 203         struct z_erofs_decompress_req *rq = ctx->rq;
 204         bool support_0padding = false, may_inplace = false;
 205         unsigned int inputmargin;
 206         u8 *out, *headpage, *src;
 207         int ret, maptype;
 208
 209         DBG_BUGON(*rq->in == NULL);
 210         headpage = kmap_local_page(*rq->in);
 211
 212         /* LZ4 decompression inplace is only safe if zero_padding is enabled */
 213         if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 214                 support_0padding = true;
 215                 ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 216                                 min_t(unsigned int, rq->inputsize,
 217                                       rq->sb->s_blocksize - rq->pageofs_in));
 218                 if (ret) {
 219                         kunmap_local(headpage);
 220                         return ret;
 221                 }
 222                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 223                                 (rq->sb->s_blocksize - 1));
 224         }
 225
 226         inputmargin = rq->pageofs_in;
 227         src = z_erofs_lz4_handle_overlap(ctx, headpage, dst, &inputmargin,
 228                                          &maptype, may_inplace);
 229         if (IS_ERR(src))
 230                 return PTR_ERR(src);
 231
 232         out = dst + rq->pageofs_out;
 233         /* legacy format could compress extra data in a pcluster. */
 234         if (rq->partial_decoding || !support_0padding)
 235                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 236                                 rq->inputsize, rq->outputsize, rq->outputsize);
 237         else
 238                 ret = LZ4_decompress_safe(src + inputmargin, out,
 239                                           rq->inputsize, rq->outputsize);
 240
 241         if (ret != rq->outputsize) {
 242                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 243                           ret, rq->inputsize, inputmargin, rq->outputsize);
 244                 if (ret >= 0)
 245                         memset(out + ret, 0, rq->outputsize - ret);
 246                 ret = -EFSCORRUPTED;
 247         } else {
 248                 ret = 0;
 249         }
 250
 251         if (maptype == 0) {
 252                 kunmap_local(headpage);
 253         } else if (maptype == 1) {
 254                 vm_unmap_ram(src, ctx->inpages);
 255         } else if (maptype == 2) {
 256                 z_erofs_put_gbuf(src);
 257         } else if (maptype != 3) {
 258                 DBG_BUGON(1);
 259                 return -EFAULT;
 260         }
 261         return ret;
 262 }
 263
 264 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 265                                   struct page **pagepool)
 266 {
 267         struct z_erofs_lz4_decompress_ctx ctx;
 268         unsigned int dst_maptype;
 269         void *dst;
 270         int ret;
 271
 272         ctx.rq = rq;
 273         ctx.oend = rq->pageofs_out + rq->outputsize;
 274         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 275         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 276
 277         /* one optimized fast path only for non bigpcluster cases yet */
 278         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 279                 DBG_BUGON(!*rq->out);
 280                 dst = kmap_local_page(*rq->out);
 281                 dst_maptype = 0;
 282                 goto dstmap_out;
 283         }
 284
 285         /* general decoding path which can be used for all cases */
 286         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 287         if (ret < 0) {
 288                 return ret;
 289         } else if (ret > 0) {
 290                 dst = page_address(*rq->out);
 291                 dst_maptype = 1;
 292         } else {
 293                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 294                 if (!dst)
 295                         return -ENOMEM;
 296                 dst_maptype = 2;
 297         }
 298
 299 dstmap_out:
 300         ret = z_erofs_lz4_decompress_mem(&ctx, dst);
 301         if (!dst_maptype)
 302                 kunmap_local(dst);
 303         else if (dst_maptype == 2)
 304                 vm_unmap_ram(dst, ctx.outpages);
 305         return ret;
 306 }
 307
 308 static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 309                                    struct page **pagepool)
 310 {
 311         const unsigned int nrpages_in =
 312                 PAGE_ALIGN(rq->pageofs_in + rq->inputsize) >> PAGE_SHIFT;
 313         const unsigned int nrpages_out =
 314                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 315         const unsigned int bs = rq->sb->s_blocksize;
 316         unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
 317         u8 *kin;
 318
 319         if (rq->outputsize > rq->inputsize)
 320                 return -EOPNOTSUPP;
 321         if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
 322                 cur = bs - (rq->pageofs_out & (bs - 1));
 323                 pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
 324                 cur = min(cur, rq->outputsize);
 325                 if (cur && rq->out[0]) {
 326                         kin = kmap_local_page(rq->in[nrpages_in - 1]);
 327                         if (rq->out[0] == rq->in[nrpages_in - 1]) {
 328                                 memmove(kin + rq->pageofs_out, kin + pi, cur);
 329                                 flush_dcache_page(rq->out[0]);
 330                         } else {
 331                                 memcpy_to_page(rq->out[0], rq->pageofs_out,
 332                                                kin + pi, cur);
 333                         }
 334                         kunmap_local(kin);
 335                 }
 336                 rq->outputsize -= cur;
 337         }
 338
 339         for (; rq->outputsize; rq->pageofs_in = 0, cur += PAGE_SIZE, ni++) {
 340                 insz = min(PAGE_SIZE - rq->pageofs_in, rq->outputsize);
 341                 rq->outputsize -= insz;
 342                 if (!rq->in[ni])
 343                         continue;
 344                 kin = kmap_local_page(rq->in[ni]);
 345                 pi = 0;
 346                 do {
 347                         no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT;
 348                         po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
 349                         DBG_BUGON(no >= nrpages_out);
 350                         cnt = min(insz - pi, PAGE_SIZE - po);
 351                         if (rq->out[no] == rq->in[ni]) {
 352                                 memmove(kin + po,
 353                                         kin + rq->pageofs_in + pi, cnt);
 354                                 flush_dcache_page(rq->out[no]);
 355                         } else if (rq->out[no]) {
 356                                 memcpy_to_page(rq->out[no], po,
 357                                                kin + rq->pageofs_in + pi, cnt);
 358                         }
 359                         pi += cnt;
 360                 } while (pi < insz);
 361                 kunmap_local(kin);
 362         }
 363         DBG_BUGON(ni > nrpages_in);
 364         return 0;
 365 }
 366
 367 int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
 368                                void **src, struct page **pgpl)
 369 {
 370         struct z_erofs_decompress_req *rq = dctx->rq;
 371         struct super_block *sb = rq->sb;
 372         struct page **pgo, *tmppage;
 373         unsigned int j;
 374
 375         if (!dctx->avail_out) {
 376                 if (++dctx->no >= dctx->outpages || !rq->outputsize) {
 377                         erofs_err(sb, "insufficient space for decompressed data");
 378                         return -EFSCORRUPTED;
 379                 }
 380
 381                 if (dctx->kout)
 382                         kunmap_local(dctx->kout);
 383                 dctx->avail_out = min(rq->outputsize, PAGE_SIZE - rq->pageofs_out);
 384                 rq->outputsize -= dctx->avail_out;
 385                 pgo = &rq->out[dctx->no];
 386                 if (!*pgo && rq->fillgaps) {            /* deduped */
 387                         *pgo = erofs_allocpage(pgpl, rq->gfp);
 388                         if (!*pgo) {
 389                                 dctx->kout = NULL;
 390                                 return -ENOMEM;
 391                         }
 392                         set_page_private(*pgo, Z_EROFS_SHORTLIVED_PAGE);
 393                 }
 394                 if (*pgo) {
 395                         dctx->kout = kmap_local_page(*pgo);
 396                         *dst = dctx->kout + rq->pageofs_out;
 397                 } else {
 398                         *dst = dctx->kout = NULL;
 399                 }
 400                 rq->pageofs_out = 0;
 401         }
 402
 403         if (dctx->inbuf_pos == dctx->inbuf_sz && rq->inputsize) {
 404                 if (++dctx->ni >= dctx->inpages) {
 405                         erofs_err(sb, "invalid compressed data");
 406                         return -EFSCORRUPTED;
 407                 }
 408                 if (dctx->kout) /* unlike kmap(), take care of the orders */
 409                         kunmap_local(dctx->kout);
 410                 kunmap_local(dctx->kin);
 411
 412                 dctx->inbuf_sz = min_t(u32, rq->inputsize, PAGE_SIZE);
 413                 rq->inputsize -= dctx->inbuf_sz;
 414                 dctx->kin = kmap_local_page(rq->in[dctx->ni]);
 415                 *src = dctx->kin;
 416                 dctx->bounced = false;
 417                 if (dctx->kout) {
 418                         j = (u8 *)*dst - dctx->kout;
 419                         dctx->kout = kmap_local_page(rq->out[dctx->no]);
 420                         *dst = dctx->kout + j;
 421                 }
 422                 dctx->inbuf_pos = 0;
 423         }
 424
 425         /*
 426          * Handle overlapping: Use the given bounce buffer if the input data is
 427          * under processing; Or utilize short-lived pages from the on-stack page
 428          * pool, where pages are shared among the same request.  Note that only
 429          * a few inplace I/O pages need to be doubled.
 430          */
 431         if (!dctx->bounced && rq->out[dctx->no] == rq->in[dctx->ni]) {
 432                 memcpy(dctx->bounce, *src, dctx->inbuf_sz);
 433                 *src = dctx->bounce;
 434                 dctx->bounced = true;
 435         }
 436
 437         for (j = dctx->ni + 1; j < dctx->inpages; ++j) {
 438                 if (rq->out[dctx->no] != rq->in[j])
 439                         continue;
 440                 tmppage = erofs_allocpage(pgpl, rq->gfp);
 441                 if (!tmppage)
 442                         return -ENOMEM;
 443                 set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
 444                 copy_highpage(tmppage, rq->in[j]);
 445                 rq->in[j] = tmppage;
 446         }
 447         return 0;
 448 }
 449
 450 const struct z_erofs_decompressor *z_erofs_decomp[] = {
 451         [Z_EROFS_COMPRESSION_SHIFTED] = &(const struct z_erofs_decompressor) {
 452                 .decompress = z_erofs_transform_plain,
 453                 .name = "shifted"
 454         },
 455         [Z_EROFS_COMPRESSION_INTERLACED] = &(const struct z_erofs_decompressor) {
 456                 .decompress = z_erofs_transform_plain,
 457                 .name = "interlaced"
 458         },
 459         [Z_EROFS_COMPRESSION_LZ4] = &(const struct z_erofs_decompressor) {
 460                 .config = z_erofs_load_lz4_config,
 461                 .decompress = z_erofs_lz4_decompress,
 462                 .init = z_erofs_gbuf_init,
 463                 .exit = z_erofs_gbuf_exit,
 464                 .name = "lz4"
 465         },
 466 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 467         [Z_EROFS_COMPRESSION_LZMA] = &z_erofs_lzma_decomp,
 468 #endif
 469 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 470         [Z_EROFS_COMPRESSION_DEFLATE] = &z_erofs_deflate_decomp,
 471 #endif
 472 #ifdef CONFIG_EROFS_FS_ZIP_ZSTD
 473         [Z_EROFS_COMPRESSION_ZSTD] = &z_erofs_zstd_decomp,
 474 #endif
 475 };
 476
 477 int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
 478 {
 479         struct erofs_sb_info *sbi = EROFS_SB(sb);
 480         struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 481         unsigned int algs, alg;
 482         erofs_off_t offset;
 483         int size, ret = 0;
 484
 485         if (!erofs_sb_has_compr_cfgs(sbi)) {
 486                 sbi->available_compr_algs = 1 << Z_EROFS_COMPRESSION_LZ4;
 487                 return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
 488         }
 489
 490         sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
 491         if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
 492                 erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
 493                           sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
 494                 return -EOPNOTSUPP;
 495         }
 496
 497         erofs_init_metabuf(&buf, sb);
 498         offset = EROFS_SUPER_OFFSET + sbi->sb_size;
 499         alg = 0;
 500         for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
 501                 const struct z_erofs_decompressor *dec = z_erofs_decomp[alg];
 502                 void *data;
 503
 504                 if (!(algs & 1))
 505                         continue;
 506
 507                 data = erofs_read_metadata(sb, &buf, &offset, &size);
 508                 if (IS_ERR(data)) {
 509                         ret = PTR_ERR(data);
 510                         break;
 511                 }
 512
 513                 if (alg < Z_EROFS_COMPRESSION_MAX && dec && dec->config) {
 514                         ret = dec->config(sb, dsb, data, size);
 515                 } else {
 516                         erofs_err(sb, "algorithm %d isn't enabled on this kernel",
 517                                   alg);
 518                         ret = -EOPNOTSUPP;
 519                 }
 520                 kfree(data);
 521                 if (ret)
 522                         break;
 523         }
 524         erofs_put_metabuf(&buf);
 525         return ret;
 526 }
 527
 528 int __init z_erofs_init_decompressor(void)
 529 {
 530         int i, err;
 531
 532         for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
 533                 err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
 534                 if (err) {
 535                         while (i--)
 536                                 if (z_erofs_decomp[i])
 537                                         z_erofs_decomp[i]->exit();
 538                         return err;
 539                 }
 540         }
 541         return 0;
 542 }
 543
 544 void z_erofs_exit_decompressor(void)
 545 {
 546         int i;
 547
 548         for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i)
 549                 if (z_erofs_decomp[i])
 550                         z_erofs_decomp[i]->exit();
 551 }