fs/btrfs/lzo.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2008 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/slab.h>
   8 #include <linux/mm.h>
   9 #include <linux/init.h>
  10 #include <linux/err.h>
  11 #include <linux/sched.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/bio.h>
  14 #include <linux/lzo.h>
  15 #include <linux/refcount.h>
  16 #include "compression.h"
  17
  18 #define LZO_LEN 4
  19
  20 /*
  21  * Btrfs LZO compression format
  22  *
  23  * Regular and inlined LZO compressed data extents consist of:
  24  *
  25  * 1.  Header
  26  *     Fixed size. LZO_LEN (4) bytes long, LE32.
  27  *     Records the total size (including the header) of compressed data.
  28  *
  29  * 2.  Segment(s)
  30  *     Variable size. Each segment includes one segment header, followed by data
  31  *     payload.
  32  *     One regular LZO compressed extent can have one or more segments.
  33  *     For inlined LZO compressed extent, only one segment is allowed.
  34  *     One segment represents at most one page of uncompressed data.
  35  *
  36  * 2.1 Segment header
  37  *     Fixed size. LZO_LEN (4) bytes long, LE32.
  38  *     Records the total size of the segment (not including the header).
  39  *     Segment header never crosses page boundary, thus it's possible to
  40  *     have at most 3 padding zeros at the end of the page.
  41  *
  42  * 2.2 Data Payload
  43  *     Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
  44  *     which is 4419 for a 4KiB page.
  45  *
  46  * Example:
  47  * Page 1:
  48  *          0     0x2   0x4   0x6   0x8   0xa   0xc   0xe     0x10
  49  * 0x0000   |  Header   | SegHdr 01 | Data payload 01 ...     |
  50  * ...
  51  * 0x0ff0   | SegHdr  N | Data payload  N     ...          |00|
  52  *                                                          ^^ padding zeros
  53  * Page 2:
  54  * 0x1000   | SegHdr N+1| Data payload N+1 ...                |
  55  */
  56
  57 struct workspace {
  58         void *mem;
  59         void *buf;      /* where decompressed data goes */
  60         void *cbuf;     /* where compressed data goes */
  61         struct list_head list;
  62 };
  63
  64 static struct workspace_manager wsm;
  65
  66 static void lzo_init_workspace_manager(void)
  67 {
  68         btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
  69 }
  70
  71 static void lzo_cleanup_workspace_manager(void)
  72 {
  73         btrfs_cleanup_workspace_manager(&wsm);
  74 }
  75
  76 static struct list_head *lzo_get_workspace(unsigned int level)
  77 {
  78         return btrfs_get_workspace(&wsm, level);
  79 }
  80
  81 static void lzo_put_workspace(struct list_head *ws)
  82 {
  83         btrfs_put_workspace(&wsm, ws);
  84 }
  85
  86 static void lzo_free_workspace(struct list_head *ws)
  87 {
  88         struct workspace *workspace = list_entry(ws, struct workspace, list);
  89
  90         kvfree(workspace->buf);
  91         kvfree(workspace->cbuf);
  92         kvfree(workspace->mem);
  93         kfree(workspace);
  94 }
  95
  96 static struct list_head *lzo_alloc_workspace(unsigned int level)
  97 {
  98         struct workspace *workspace;
  99
 100         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
 101         if (!workspace)
 102                 return ERR_PTR(-ENOMEM);
 103
 104         workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 105         workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
 106         workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
 107         if (!workspace->mem || !workspace->buf || !workspace->cbuf)
 108                 goto fail;
 109
 110         INIT_LIST_HEAD(&workspace->list);
 111
 112         return &workspace->list;
 113 fail:
 114         lzo_free_workspace(&workspace->list);
 115         return ERR_PTR(-ENOMEM);
 116 }
 117
 118 static inline void write_compress_length(char *buf, size_t len)
 119 {
 120         __le32 dlen;
 121
 122         dlen = cpu_to_le32(len);
 123         memcpy(buf, &dlen, LZO_LEN);
 124 }
 125
 126 static inline size_t read_compress_length(const char *buf)
 127 {
 128         __le32 dlen;
 129
 130         memcpy(&dlen, buf, LZO_LEN);
 131         return le32_to_cpu(dlen);
 132 }
 133
 134 static int lzo_compress_pages(struct list_head *ws,
 135                               struct address_space *mapping,
 136                               u64 start,
 137                               struct page **pages,
 138                               unsigned long *out_pages,
 139                               unsigned long *total_in,
 140                               unsigned long *total_out)
 141 {
 142         struct workspace *workspace = list_entry(ws, struct workspace, list);
 143         int ret = 0;
 144         char *data_in;
 145         char *cpage_out;
 146         int nr_pages = 0;
 147         struct page *in_page = NULL;
 148         struct page *out_page = NULL;
 149         unsigned long bytes_left;
 150         unsigned long len = *total_out;
 151         unsigned long nr_dest_pages = *out_pages;
 152         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 153         size_t in_len;
 154         size_t out_len;
 155         char *buf;
 156         unsigned long tot_in = 0;
 157         unsigned long tot_out = 0;
 158         unsigned long pg_bytes_left;
 159         unsigned long out_offset;
 160         unsigned long bytes;
 161
 162         *out_pages = 0;
 163         *total_out = 0;
 164         *total_in = 0;
 165
 166         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 167         data_in = kmap(in_page);
 168
 169         /*
 170          * store the size of all chunks of compressed data in
 171          * the first 4 bytes
 172          */
 173         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 174         if (out_page == NULL) {
 175                 ret = -ENOMEM;
 176                 goto out;
 177         }
 178         cpage_out = kmap(out_page);
 179         out_offset = LZO_LEN;
 180         tot_out = LZO_LEN;
 181         pages[0] = out_page;
 182         nr_pages = 1;
 183         pg_bytes_left = PAGE_SIZE - LZO_LEN;
 184
 185         /* compress at most one page of data each time */
 186         in_len = min(len, PAGE_SIZE);
 187         while (tot_in < len) {
 188                 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
 189                                        &out_len, workspace->mem);
 190                 if (ret != LZO_E_OK) {
 191                         pr_debug("BTRFS: lzo in loop returned %d\n",
 192                                ret);
 193                         ret = -EIO;
 194                         goto out;
 195                 }
 196
 197                 /* store the size of this chunk of compressed data */
 198                 write_compress_length(cpage_out + out_offset, out_len);
 199                 tot_out += LZO_LEN;
 200                 out_offset += LZO_LEN;
 201                 pg_bytes_left -= LZO_LEN;
 202
 203                 tot_in += in_len;
 204                 tot_out += out_len;
 205
 206                 /* copy bytes from the working buffer into the pages */
 207                 buf = workspace->cbuf;
 208                 while (out_len) {
 209                         bytes = min_t(unsigned long, pg_bytes_left, out_len);
 210
 211                         memcpy(cpage_out + out_offset, buf, bytes);
 212
 213                         out_len -= bytes;
 214                         pg_bytes_left -= bytes;
 215                         buf += bytes;
 216                         out_offset += bytes;
 217
 218                         /*
 219                          * we need another page for writing out.
 220                          *
 221                          * Note if there's less than 4 bytes left, we just
 222                          * skip to a new page.
 223                          */
 224                         if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
 225                             pg_bytes_left == 0) {
 226                                 if (pg_bytes_left) {
 227                                         memset(cpage_out + out_offset, 0,
 228                                                pg_bytes_left);
 229                                         tot_out += pg_bytes_left;
 230                                 }
 231
 232                                 /* we're done, don't allocate new page */
 233                                 if (out_len == 0 && tot_in >= len)
 234                                         break;
 235
 236                                 kunmap(out_page);
 237                                 if (nr_pages == nr_dest_pages) {
 238                                         out_page = NULL;
 239                                         ret = -E2BIG;
 240                                         goto out;
 241                                 }
 242
 243                                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 244                                 if (out_page == NULL) {
 245                                         ret = -ENOMEM;
 246                                         goto out;
 247                                 }
 248                                 cpage_out = kmap(out_page);
 249                                 pages[nr_pages++] = out_page;
 250
 251                                 pg_bytes_left = PAGE_SIZE;
 252                                 out_offset = 0;
 253                         }
 254                 }
 255
 256                 /* we're making it bigger, give up */
 257                 if (tot_in > 8192 && tot_in < tot_out) {
 258                         ret = -E2BIG;
 259                         goto out;
 260                 }
 261
 262                 /* we're all done */
 263                 if (tot_in >= len)
 264                         break;
 265
 266                 if (tot_out > max_out)
 267                         break;
 268
 269                 bytes_left = len - tot_in;
 270                 kunmap(in_page);
 271                 put_page(in_page);
 272
 273                 start += PAGE_SIZE;
 274                 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 275                 data_in = kmap(in_page);
 276                 in_len = min(bytes_left, PAGE_SIZE);
 277         }
 278
 279         if (tot_out >= tot_in) {
 280                 ret = -E2BIG;
 281                 goto out;
 282         }
 283
 284         /* store the size of all chunks of compressed data */
 285         cpage_out = kmap(pages[0]);
 286         write_compress_length(cpage_out, tot_out);
 287
 288         kunmap(pages[0]);
 289
 290         ret = 0;
 291         *total_out = tot_out;
 292         *total_in = tot_in;
 293 out:
 294         *out_pages = nr_pages;
 295         if (out_page)
 296                 kunmap(out_page);
 297
 298         if (in_page) {
 299                 kunmap(in_page);
 300                 put_page(in_page);
 301         }
 302
 303         return ret;
 304 }
 305
 306 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 307 {
 308         struct workspace *workspace = list_entry(ws, struct workspace, list);
 309         int ret = 0, ret2;
 310         char *data_in;
 311         unsigned long page_in_index = 0;
 312         size_t srclen = cb->compressed_len;
 313         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 314         unsigned long buf_start;
 315         unsigned long buf_offset = 0;
 316         unsigned long bytes;
 317         unsigned long working_bytes;
 318         size_t in_len;
 319         size_t out_len;
 320         const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
 321         unsigned long in_offset;
 322         unsigned long in_page_bytes_left;
 323         unsigned long tot_in;
 324         unsigned long tot_out;
 325         unsigned long tot_len;
 326         char *buf;
 327         bool may_late_unmap, need_unmap;
 328         struct page **pages_in = cb->compressed_pages;
 329         u64 disk_start = cb->start;
 330         struct bio *orig_bio = cb->orig_bio;
 331
 332         data_in = kmap(pages_in[0]);
 333         tot_len = read_compress_length(data_in);
 334         /*
 335          * Compressed data header check.
 336          *
 337          * The real compressed size can't exceed the maximum extent length, and
 338          * all pages should be used (whole unused page with just the segment
 339          * header is not possible).  If this happens it means the compressed
 340          * extent is corrupted.
 341          */
 342         if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
 343             tot_len < srclen - PAGE_SIZE) {
 344                 ret = -EUCLEAN;
 345                 goto done;
 346         }
 347
 348         tot_in = LZO_LEN;
 349         in_offset = LZO_LEN;
 350         in_page_bytes_left = PAGE_SIZE - LZO_LEN;
 351
 352         tot_out = 0;
 353
 354         while (tot_in < tot_len) {
 355                 in_len = read_compress_length(data_in + in_offset);
 356                 in_page_bytes_left -= LZO_LEN;
 357                 in_offset += LZO_LEN;
 358                 tot_in += LZO_LEN;
 359
 360                 /*
 361                  * Segment header check.
 362                  *
 363                  * The segment length must not exceed the maximum LZO
 364                  * compression size, nor the total compressed size.
 365                  */
 366                 if (in_len > max_segment_len || tot_in + in_len > tot_len) {
 367                         ret = -EUCLEAN;
 368                         goto done;
 369                 }
 370
 371                 tot_in += in_len;
 372                 working_bytes = in_len;
 373                 may_late_unmap = need_unmap = false;
 374
 375                 /* fast path: avoid using the working buffer */
 376                 if (in_page_bytes_left >= in_len) {
 377                         buf = data_in + in_offset;
 378                         bytes = in_len;
 379                         may_late_unmap = true;
 380                         goto cont;
 381                 }
 382
 383                 /* copy bytes from the pages into the working buffer */
 384                 buf = workspace->cbuf;
 385                 buf_offset = 0;
 386                 while (working_bytes) {
 387                         bytes = min(working_bytes, in_page_bytes_left);
 388
 389                         memcpy(buf + buf_offset, data_in + in_offset, bytes);
 390                         buf_offset += bytes;
 391 cont:
 392                         working_bytes -= bytes;
 393                         in_page_bytes_left -= bytes;
 394                         in_offset += bytes;
 395
 396                         /* check if we need to pick another page */
 397                         if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
 398                             || in_page_bytes_left == 0) {
 399                                 tot_in += in_page_bytes_left;
 400
 401                                 if (working_bytes == 0 && tot_in >= tot_len)
 402                                         break;
 403
 404                                 if (page_in_index + 1 >= total_pages_in) {
 405                                         ret = -EIO;
 406                                         goto done;
 407                                 }
 408
 409                                 if (may_late_unmap)
 410                                         need_unmap = true;
 411                                 else
 412                                         kunmap(pages_in[page_in_index]);
 413
 414                                 data_in = kmap(pages_in[++page_in_index]);
 415
 416                                 in_page_bytes_left = PAGE_SIZE;
 417                                 in_offset = 0;
 418                         }
 419                 }
 420
 421                 out_len = max_segment_len;
 422                 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
 423                                             &out_len);
 424                 if (need_unmap)
 425                         kunmap(pages_in[page_in_index - 1]);
 426                 if (ret != LZO_E_OK) {
 427                         pr_warn("BTRFS: decompress failed\n");
 428                         ret = -EIO;
 429                         break;
 430                 }
 431
 432                 buf_start = tot_out;
 433                 tot_out += out_len;
 434
 435                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 436                                                  tot_out, disk_start, orig_bio);
 437                 if (ret2 == 0)
 438                         break;
 439         }
 440 done:
 441         kunmap(pages_in[page_in_index]);
 442         if (!ret)
 443                 zero_fill_bio(orig_bio);
 444         return ret;
 445 }
 446
 447 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 448                           struct page *dest_page,
 449                           unsigned long start_byte,
 450                           size_t srclen, size_t destlen)
 451 {
 452         struct workspace *workspace = list_entry(ws, struct workspace, list);
 453         size_t in_len;
 454         size_t out_len;
 455         size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
 456         int ret = 0;
 457         char *kaddr;
 458         unsigned long bytes;
 459
 460         if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
 461                 return -EUCLEAN;
 462
 463         in_len = read_compress_length(data_in);
 464         if (in_len != srclen)
 465                 return -EUCLEAN;
 466         data_in += LZO_LEN;
 467
 468         in_len = read_compress_length(data_in);
 469         if (in_len != srclen - LZO_LEN * 2) {
 470                 ret = -EUCLEAN;
 471                 goto out;
 472         }
 473         data_in += LZO_LEN;
 474
 475         out_len = PAGE_SIZE;
 476         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
 477         if (ret != LZO_E_OK) {
 478                 pr_warn("BTRFS: decompress failed!\n");
 479                 ret = -EIO;
 480                 goto out;
 481         }
 482
 483         if (out_len < start_byte) {
 484                 ret = -EIO;
 485                 goto out;
 486         }
 487
 488         /*
 489          * the caller is already checking against PAGE_SIZE, but lets
 490          * move this check closer to the memcpy/memset
 491          */
 492         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 493         bytes = min_t(unsigned long, destlen, out_len - start_byte);
 494
 495         kaddr = kmap_atomic(dest_page);
 496         memcpy(kaddr, workspace->buf + start_byte, bytes);
 497
 498         /*
 499          * btrfs_getblock is doing a zero on the tail of the page too,
 500          * but this will cover anything missing from the decompressed
 501          * data.
 502          */
 503         if (bytes < destlen)
 504                 memset(kaddr+bytes, 0, destlen-bytes);
 505         kunmap_atomic(kaddr);
 506 out:
 507         return ret;
 508 }
 509
 510 static void lzo_set_level(struct list_head *ws, unsigned int type)
 511 {
 512 }
 513
 514 const struct btrfs_compress_op btrfs_lzo_compress = {
 515         .init_workspace_manager = lzo_init_workspace_manager,
 516         .cleanup_workspace_manager = lzo_cleanup_workspace_manager,
 517         .get_workspace          = lzo_get_workspace,
 518         .put_workspace          = lzo_put_workspace,
 519         .alloc_workspace        = lzo_alloc_workspace,
 520         .free_workspace         = lzo_free_workspace,
 521         .compress_pages         = lzo_compress_pages,
 522         .decompress_bio         = lzo_decompress_bio,
 523         .decompress             = lzo_decompress,
 524         .set_level              = lzo_set_level,
 525 };