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  */
   6 #include "compress.h"
   7 #include <linux/lz4.h>
   8
   9 #ifndef LZ4_DISTANCE_MAX        /* history window size */
  10 #define LZ4_DISTANCE_MAX 65535  /* set to maximum value by default */
  11 #endif
  12
  13 #define LZ4_MAX_DISTANCE_PAGES  (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
  14 #ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
  15 #define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize)  (((srcsize) >> 8) + 32)
  16 #endif
  17
  18 struct z_erofs_lz4_decompress_ctx {
  19         struct z_erofs_decompress_req *rq;
  20         /* # of encoded, decoded pages */
  21         unsigned int inpages, outpages;
  22         /* decoded block total length (used for in-place decompression) */
  23         unsigned int oend;
  24 };
  25
  26 static int z_erofs_load_lz4_config(struct super_block *sb,
  27                             struct erofs_super_block *dsb, void *data, int size)
  28 {
  29         struct erofs_sb_info *sbi = EROFS_SB(sb);
  30         struct z_erofs_lz4_cfgs *lz4 = data;
  31         u16 distance;
  32
  33         if (lz4) {
  34                 if (size < sizeof(struct z_erofs_lz4_cfgs)) {
  35                         erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
  36                         return -EINVAL;
  37                 }
  38                 distance = le16_to_cpu(lz4->max_distance);
  39
  40                 sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
  41                 if (!sbi->lz4.max_pclusterblks) {
  42                         sbi->lz4.max_pclusterblks = 1;  /* reserved case */
  43                 } else if (sbi->lz4.max_pclusterblks >
  44                            erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) {
  45                         erofs_err(sb, "too large lz4 pclusterblks %u",
  46                                   sbi->lz4.max_pclusterblks);
  47                         return -EINVAL;
  48                 }
  49         } else {
  50                 distance = le16_to_cpu(dsb->u1.lz4_max_distance);
  51                 sbi->lz4.max_pclusterblks = 1;
  52         }
  53
  54         sbi->lz4.max_distance_pages = distance ?
  55                                         DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
  56                                         LZ4_MAX_DISTANCE_PAGES;
  57         return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
  58 }
  59
  60 /*
  61  * Fill all gaps with bounce pages if it's a sparse page list. Also check if
  62  * all physical pages are consecutive, which can be seen for moderate CR.
  63  */
  64 static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
  65                                         struct page **pagepool)
  66 {
  67         struct z_erofs_decompress_req *rq = ctx->rq;
  68         struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
  69         unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
  70                                            BITS_PER_LONG)] = { 0 };
  71         unsigned int lz4_max_distance_pages =
  72                                 EROFS_SB(rq->sb)->lz4.max_distance_pages;
  73         void *kaddr = NULL;
  74         unsigned int i, j, top;
  75
  76         top = 0;
  77         for (i = j = 0; i < ctx->outpages; ++i, ++j) {
  78                 struct page *const page = rq->out[i];
  79                 struct page *victim;
  80
  81                 if (j >= lz4_max_distance_pages)
  82                         j = 0;
  83
  84                 /* 'valid' bounced can only be tested after a complete round */
  85                 if (!rq->fillgaps && test_bit(j, bounced)) {
  86                         DBG_BUGON(i < lz4_max_distance_pages);
  87                         DBG_BUGON(top >= lz4_max_distance_pages);
  88                         availables[top++] = rq->out[i - lz4_max_distance_pages];
  89                 }
  90
  91                 if (page) {
  92                         __clear_bit(j, bounced);
  93                         if (!PageHighMem(page)) {
  94                                 if (!i) {
  95                                         kaddr = page_address(page);
  96                                         continue;
  97                                 }
  98                                 if (kaddr &&
  99                                     kaddr + PAGE_SIZE == page_address(page)) {
 100                                         kaddr += PAGE_SIZE;
 101                                         continue;
 102                                 }
 103                         }
 104                         kaddr = NULL;
 105                         continue;
 106                 }
 107                 kaddr = NULL;
 108                 __set_bit(j, bounced);
 109
 110                 if (top) {
 111                         victim = availables[--top];
 112                         get_page(victim);
 113                 } else {
 114                         victim = erofs_allocpage(pagepool, rq->gfp);
 115                         if (!victim)
 116                                 return -ENOMEM;
 117                         set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
 118                 }
 119                 rq->out[i] = victim;
 120         }
 121         return kaddr ? 1 : 0;
 122 }
 123
 124 static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
 125                         void *inpage, void *out, unsigned int *inputmargin,
 126                         int *maptype, bool may_inplace)
 127 {
 128         struct z_erofs_decompress_req *rq = ctx->rq;
 129         unsigned int omargin, total, i;
 130         struct page **in;
 131         void *src, *tmp;
 132
 133         if (rq->inplace_io) {
 134                 omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
 135                 if (rq->partial_decoding || !may_inplace ||
 136                     omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
 137                         goto docopy;
 138
 139                 for (i = 0; i < ctx->inpages; ++i)
 140                         if (rq->out[ctx->outpages - ctx->inpages + i] !=
 141                             rq->in[i])
 142                                 goto docopy;
 143                 kunmap_local(inpage);
 144                 *maptype = 3;
 145                 return out + ((ctx->outpages - ctx->inpages) << PAGE_SHIFT);
 146         }
 147
 148         if (ctx->inpages <= 1) {
 149                 *maptype = 0;
 150                 return inpage;
 151         }
 152         kunmap_local(inpage);
 153         src = erofs_vm_map_ram(rq->in, ctx->inpages);
 154         if (!src)
 155                 return ERR_PTR(-ENOMEM);
 156         *maptype = 1;
 157         return src;
 158
 159 docopy:
 160         /* Or copy compressed data which can be overlapped to per-CPU buffer */
 161         in = rq->in;
 162         src = erofs_get_pcpubuf(ctx->inpages);
 163         if (!src) {
 164                 DBG_BUGON(1);
 165                 kunmap_local(inpage);
 166                 return ERR_PTR(-EFAULT);
 167         }
 168
 169         tmp = src;
 170         total = rq->inputsize;
 171         while (total) {
 172                 unsigned int page_copycnt =
 173                         min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
 174
 175                 if (!inpage)
 176                         inpage = kmap_local_page(*in);
 177                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 178                 kunmap_local(inpage);
 179                 inpage = NULL;
 180                 tmp += page_copycnt;
 181                 total -= page_copycnt;
 182                 ++in;
 183                 *inputmargin = 0;
 184         }
 185         *maptype = 2;
 186         return src;
 187 }
 188
 189 /*
 190  * Get the exact inputsize with zero_padding feature.
 191  *  - For LZ4, it should work if zero_padding feature is on (5.3+);
 192  *  - For MicroLZMA, it'd be enabled all the time.
 193  */
 194 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 195                          unsigned int padbufsize)
 196 {
 197         const char *padend;
 198
 199         padend = memchr_inv(padbuf, 0, padbufsize);
 200         if (!padend)
 201                 return -EFSCORRUPTED;
 202         rq->inputsize -= padend - padbuf;
 203         rq->pageofs_in += padend - padbuf;
 204         return 0;
 205 }
 206
 207 static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
 208                                       u8 *dst)
 209 {
 210         struct z_erofs_decompress_req *rq = ctx->rq;
 211         bool support_0padding = false, may_inplace = false;
 212         unsigned int inputmargin;
 213         u8 *out, *headpage, *src;
 214         int ret, maptype;
 215
 216         DBG_BUGON(*rq->in == NULL);
 217         headpage = kmap_local_page(*rq->in);
 218
 219         /* LZ4 decompression inplace is only safe if zero_padding is enabled */
 220         if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 221                 support_0padding = true;
 222                 ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 223                                 min_t(unsigned int, rq->inputsize,
 224                                       rq->sb->s_blocksize - rq->pageofs_in));
 225                 if (ret) {
 226                         kunmap_local(headpage);
 227                         return ret;
 228                 }
 229                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 230                                 (rq->sb->s_blocksize - 1));
 231         }
 232
 233         inputmargin = rq->pageofs_in;
 234         src = z_erofs_lz4_handle_overlap(ctx, headpage, dst, &inputmargin,
 235                                          &maptype, may_inplace);
 236         if (IS_ERR(src))
 237                 return PTR_ERR(src);
 238
 239         out = dst + rq->pageofs_out;
 240         /* legacy format could compress extra data in a pcluster. */
 241         if (rq->partial_decoding || !support_0padding)
 242                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 243                                 rq->inputsize, rq->outputsize, rq->outputsize);
 244         else
 245                 ret = LZ4_decompress_safe(src + inputmargin, out,
 246                                           rq->inputsize, rq->outputsize);
 247
 248         if (ret != rq->outputsize) {
 249                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 250                           ret, rq->inputsize, inputmargin, rq->outputsize);
 251                 if (ret >= 0)
 252                         memset(out + ret, 0, rq->outputsize - ret);
 253                 ret = -EFSCORRUPTED;
 254         } else {
 255                 ret = 0;
 256         }
 257
 258         if (maptype == 0) {
 259                 kunmap_local(headpage);
 260         } else if (maptype == 1) {
 261                 vm_unmap_ram(src, ctx->inpages);
 262         } else if (maptype == 2) {
 263                 erofs_put_pcpubuf(src);
 264         } else if (maptype != 3) {
 265                 DBG_BUGON(1);
 266                 return -EFAULT;
 267         }
 268         return ret;
 269 }
 270
 271 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 272                                   struct page **pagepool)
 273 {
 274         struct z_erofs_lz4_decompress_ctx ctx;
 275         unsigned int dst_maptype;
 276         void *dst;
 277         int ret;
 278
 279         ctx.rq = rq;
 280         ctx.oend = rq->pageofs_out + rq->outputsize;
 281         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 282         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 283
 284         /* one optimized fast path only for non bigpcluster cases yet */
 285         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 286                 DBG_BUGON(!*rq->out);
 287                 dst = kmap_local_page(*rq->out);
 288                 dst_maptype = 0;
 289                 goto dstmap_out;
 290         }
 291
 292         /* general decoding path which can be used for all cases */
 293         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 294         if (ret < 0) {
 295                 return ret;
 296         } else if (ret > 0) {
 297                 dst = page_address(*rq->out);
 298                 dst_maptype = 1;
 299         } else {
 300                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 301                 if (!dst)
 302                         return -ENOMEM;
 303                 dst_maptype = 2;
 304         }
 305
 306 dstmap_out:
 307         ret = z_erofs_lz4_decompress_mem(&ctx, dst);
 308         if (!dst_maptype)
 309                 kunmap_local(dst);
 310         else if (dst_maptype == 2)
 311                 vm_unmap_ram(dst, ctx.outpages);
 312         return ret;
 313 }
 314
 315 static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 316                                    struct page **pagepool)
 317 {
 318         const unsigned int nrpages_in =
 319                 PAGE_ALIGN(rq->pageofs_in + rq->inputsize) >> PAGE_SHIFT;
 320         const unsigned int nrpages_out =
 321                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 322         const unsigned int bs = rq->sb->s_blocksize;
 323         unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
 324         u8 *kin;
 325
 326         if (rq->outputsize > rq->inputsize)
 327                 return -EOPNOTSUPP;
 328         if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
 329                 cur = bs - (rq->pageofs_out & (bs - 1));
 330                 pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
 331                 cur = min(cur, rq->outputsize);
 332                 if (cur && rq->out[0]) {
 333                         kin = kmap_local_page(rq->in[nrpages_in - 1]);
 334                         if (rq->out[0] == rq->in[nrpages_in - 1]) {
 335                                 memmove(kin + rq->pageofs_out, kin + pi, cur);
 336                                 flush_dcache_page(rq->out[0]);
 337                         } else {
 338                                 memcpy_to_page(rq->out[0], rq->pageofs_out,
 339                                                kin + pi, cur);
 340                         }
 341                         kunmap_local(kin);
 342                 }
 343                 rq->outputsize -= cur;
 344         }
 345
 346         for (; rq->outputsize; rq->pageofs_in = 0, cur += PAGE_SIZE, ni++) {
 347                 insz = min(PAGE_SIZE - rq->pageofs_in, rq->outputsize);
 348                 rq->outputsize -= insz;
 349                 if (!rq->in[ni])
 350                         continue;
 351                 kin = kmap_local_page(rq->in[ni]);
 352                 pi = 0;
 353                 do {
 354                         no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT;
 355                         po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
 356                         DBG_BUGON(no >= nrpages_out);
 357                         cnt = min(insz - pi, PAGE_SIZE - po);
 358                         if (rq->out[no] == rq->in[ni]) {
 359                                 memmove(kin + po,
 360                                         kin + rq->pageofs_in + pi, cnt);
 361                                 flush_dcache_page(rq->out[no]);
 362                         } else if (rq->out[no]) {
 363                                 memcpy_to_page(rq->out[no], po,
 364                                                kin + rq->pageofs_in + pi, cnt);
 365                         }
 366                         pi += cnt;
 367                 } while (pi < insz);
 368                 kunmap_local(kin);
 369         }
 370         DBG_BUGON(ni > nrpages_in);
 371         return 0;
 372 }
 373
 374 const struct z_erofs_decompressor erofs_decompressors[] = {
 375         [Z_EROFS_COMPRESSION_SHIFTED] = {
 376                 .decompress = z_erofs_transform_plain,
 377                 .name = "shifted"
 378         },
 379         [Z_EROFS_COMPRESSION_INTERLACED] = {
 380                 .decompress = z_erofs_transform_plain,
 381                 .name = "interlaced"
 382         },
 383         [Z_EROFS_COMPRESSION_LZ4] = {
 384                 .config = z_erofs_load_lz4_config,
 385                 .decompress = z_erofs_lz4_decompress,
 386                 .name = "lz4"
 387         },
 388 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 389         [Z_EROFS_COMPRESSION_LZMA] = {
 390                 .config = z_erofs_load_lzma_config,
 391                 .decompress = z_erofs_lzma_decompress,
 392                 .name = "lzma"
 393         },
 394 #endif
 395 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 396         [Z_EROFS_COMPRESSION_DEFLATE] = {
 397                 .config = z_erofs_load_deflate_config,
 398                 .decompress = z_erofs_deflate_decompress,
 399                 .name = "deflate"
 400         },
 401 #endif
 402 };
 403
 404 int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
 405 {
 406         struct erofs_sb_info *sbi = EROFS_SB(sb);
 407         struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 408         unsigned int algs, alg;
 409         erofs_off_t offset;
 410         int size, ret = 0;
 411
 412         if (!erofs_sb_has_compr_cfgs(sbi)) {
 413                 sbi->available_compr_algs = 1 << Z_EROFS_COMPRESSION_LZ4;
 414                 return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
 415         }
 416
 417         sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
 418         if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
 419                 erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
 420                           sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
 421                 return -EOPNOTSUPP;
 422         }
 423
 424         erofs_init_metabuf(&buf, sb);
 425         offset = EROFS_SUPER_OFFSET + sbi->sb_size;
 426         alg = 0;
 427         for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
 428                 void *data;
 429
 430                 if (!(algs & 1))
 431                         continue;
 432
 433                 data = erofs_read_metadata(sb, &buf, &offset, &size);
 434                 if (IS_ERR(data)) {
 435                         ret = PTR_ERR(data);
 436                         break;
 437                 }
 438
 439                 if (alg >= ARRAY_SIZE(erofs_decompressors) ||
 440                     !erofs_decompressors[alg].config) {
 441                         erofs_err(sb, "algorithm %d isn't enabled on this kernel",
 442                                   alg);
 443                         ret = -EOPNOTSUPP;
 444                 } else {
 445                         ret = erofs_decompressors[alg].config(sb,
 446                                         dsb, data, size);
 447                 }
 448
 449                 kfree(data);
 450                 if (ret)
 451                         break;
 452         }
 453         erofs_put_metabuf(&buf);
 454         return ret;
 455 }