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 #include "ctree.h"
  18
  19 #define LZO_LEN 4
  20
  21 /*
  22  * Btrfs LZO compression format
  23  *
  24  * Regular and inlined LZO compressed data extents consist of:
  25  *
  26  * 1.  Header
  27  *     Fixed size. LZO_LEN (4) bytes long, LE32.
  28  *     Records the total size (including the header) of compressed data.
  29  *
  30  * 2.  Segment(s)
  31  *     Variable size. Each segment includes one segment header, followed by data
  32  *     payload.
  33  *     One regular LZO compressed extent can have one or more segments.
  34  *     For inlined LZO compressed extent, only one segment is allowed.
  35  *     One segment represents at most one page of uncompressed data.
  36  *
  37  * 2.1 Segment header
  38  *     Fixed size. LZO_LEN (4) bytes long, LE32.
  39  *     Records the total size of the segment (not including the header).
  40  *     Segment header never crosses page boundary, thus it's possible to
  41  *     have at most 3 padding zeros at the end of the page.
  42  *
  43  * 2.2 Data Payload
  44  *     Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
  45  *     which is 4419 for a 4KiB page.
  46  *
  47  * Example:
  48  * Page 1:
  49  *          0     0x2   0x4   0x6   0x8   0xa   0xc   0xe     0x10
  50  * 0x0000   |  Header   | SegHdr 01 | Data payload 01 ...     |
  51  * ...
  52  * 0x0ff0   | SegHdr  N | Data payload  N     ...          |00|
  53  *                                                          ^^ padding zeros
  54  * Page 2:
  55  * 0x1000   | SegHdr N+1| Data payload N+1 ...                |
  56  */
  57
  58 struct workspace {
  59         void *mem;
  60         void *buf;      /* where decompressed data goes */
  61         void *cbuf;     /* where compressed data goes */
  62         struct list_head list;
  63 };
  64
  65 static struct workspace_manager wsm;
  66
  67 void lzo_free_workspace(struct list_head *ws)
  68 {
  69         struct workspace *workspace = list_entry(ws, struct workspace, list);
  70
  71         kvfree(workspace->buf);
  72         kvfree(workspace->cbuf);
  73         kvfree(workspace->mem);
  74         kfree(workspace);
  75 }
  76
  77 struct list_head *lzo_alloc_workspace(unsigned int level)
  78 {
  79         struct workspace *workspace;
  80
  81         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  82         if (!workspace)
  83                 return ERR_PTR(-ENOMEM);
  84
  85         workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
  86         workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  87         workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  88         if (!workspace->mem || !workspace->buf || !workspace->cbuf)
  89                 goto fail;
  90
  91         INIT_LIST_HEAD(&workspace->list);
  92
  93         return &workspace->list;
  94 fail:
  95         lzo_free_workspace(&workspace->list);
  96         return ERR_PTR(-ENOMEM);
  97 }
  98
  99 static inline void write_compress_length(char *buf, size_t len)
 100 {
 101         __le32 dlen;
 102
 103         dlen = cpu_to_le32(len);
 104         memcpy(buf, &dlen, LZO_LEN);
 105 }
 106
 107 static inline size_t read_compress_length(const char *buf)
 108 {
 109         __le32 dlen;
 110
 111         memcpy(&dlen, buf, LZO_LEN);
 112         return le32_to_cpu(dlen);
 113 }
 114
 115 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
 116                 u64 start, struct page **pages, unsigned long *out_pages,
 117                 unsigned long *total_in, unsigned long *total_out)
 118 {
 119         struct workspace *workspace = list_entry(ws, struct workspace, list);
 120         int ret = 0;
 121         char *data_in;
 122         char *cpage_out, *sizes_ptr;
 123         int nr_pages = 0;
 124         struct page *in_page = NULL;
 125         struct page *out_page = NULL;
 126         unsigned long bytes_left;
 127         unsigned long len = *total_out;
 128         unsigned long nr_dest_pages = *out_pages;
 129         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 130         size_t in_len;
 131         size_t out_len;
 132         char *buf;
 133         unsigned long tot_in = 0;
 134         unsigned long tot_out = 0;
 135         unsigned long pg_bytes_left;
 136         unsigned long out_offset;
 137         unsigned long bytes;
 138
 139         *out_pages = 0;
 140         *total_out = 0;
 141         *total_in = 0;
 142
 143         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 144         data_in = page_address(in_page);
 145
 146         /*
 147          * store the size of all chunks of compressed data in
 148          * the first 4 bytes
 149          */
 150         out_page = alloc_page(GFP_NOFS);
 151         if (out_page == NULL) {
 152                 ret = -ENOMEM;
 153                 goto out;
 154         }
 155         cpage_out = page_address(out_page);
 156         out_offset = LZO_LEN;
 157         tot_out = LZO_LEN;
 158         pages[0] = out_page;
 159         nr_pages = 1;
 160         pg_bytes_left = PAGE_SIZE - LZO_LEN;
 161
 162         /* compress at most one page of data each time */
 163         in_len = min(len, PAGE_SIZE);
 164         while (tot_in < len) {
 165                 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
 166                                        &out_len, workspace->mem);
 167                 if (ret != LZO_E_OK) {
 168                         pr_debug("BTRFS: lzo in loop returned %d\n",
 169                                ret);
 170                         ret = -EIO;
 171                         goto out;
 172                 }
 173
 174                 /* store the size of this chunk of compressed data */
 175                 write_compress_length(cpage_out + out_offset, out_len);
 176                 tot_out += LZO_LEN;
 177                 out_offset += LZO_LEN;
 178                 pg_bytes_left -= LZO_LEN;
 179
 180                 tot_in += in_len;
 181                 tot_out += out_len;
 182
 183                 /* copy bytes from the working buffer into the pages */
 184                 buf = workspace->cbuf;
 185                 while (out_len) {
 186                         bytes = min_t(unsigned long, pg_bytes_left, out_len);
 187
 188                         memcpy(cpage_out + out_offset, buf, bytes);
 189
 190                         out_len -= bytes;
 191                         pg_bytes_left -= bytes;
 192                         buf += bytes;
 193                         out_offset += bytes;
 194
 195                         /*
 196                          * we need another page for writing out.
 197                          *
 198                          * Note if there's less than 4 bytes left, we just
 199                          * skip to a new page.
 200                          */
 201                         if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
 202                             pg_bytes_left == 0) {
 203                                 if (pg_bytes_left) {
 204                                         memset(cpage_out + out_offset, 0,
 205                                                pg_bytes_left);
 206                                         tot_out += pg_bytes_left;
 207                                 }
 208
 209                                 /* we're done, don't allocate new page */
 210                                 if (out_len == 0 && tot_in >= len)
 211                                         break;
 212
 213                                 if (nr_pages == nr_dest_pages) {
 214                                         out_page = NULL;
 215                                         ret = -E2BIG;
 216                                         goto out;
 217                                 }
 218
 219                                 out_page = alloc_page(GFP_NOFS);
 220                                 if (out_page == NULL) {
 221                                         ret = -ENOMEM;
 222                                         goto out;
 223                                 }
 224                                 cpage_out = page_address(out_page);
 225                                 pages[nr_pages++] = out_page;
 226
 227                                 pg_bytes_left = PAGE_SIZE;
 228                                 out_offset = 0;
 229                         }
 230                 }
 231
 232                 /* we're making it bigger, give up */
 233                 if (tot_in > 8192 && tot_in < tot_out) {
 234                         ret = -E2BIG;
 235                         goto out;
 236                 }
 237
 238                 /* we're all done */
 239                 if (tot_in >= len)
 240                         break;
 241
 242                 if (tot_out > max_out)
 243                         break;
 244
 245                 bytes_left = len - tot_in;
 246                 put_page(in_page);
 247
 248                 start += PAGE_SIZE;
 249                 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 250                 data_in = page_address(in_page);
 251                 in_len = min(bytes_left, PAGE_SIZE);
 252         }
 253
 254         if (tot_out >= tot_in) {
 255                 ret = -E2BIG;
 256                 goto out;
 257         }
 258
 259         /* store the size of all chunks of compressed data */
 260         sizes_ptr = page_address(pages[0]);
 261         write_compress_length(sizes_ptr, tot_out);
 262
 263         ret = 0;
 264         *total_out = tot_out;
 265         *total_in = tot_in;
 266 out:
 267         *out_pages = nr_pages;
 268
 269         if (in_page)
 270                 put_page(in_page);
 271
 272         return ret;
 273 }
 274
 275 /*
 276  * Copy the compressed segment payload into @dest.
 277  *
 278  * For the payload there will be no padding, just need to do page switching.
 279  */
 280 static void copy_compressed_segment(struct compressed_bio *cb,
 281                                     char *dest, u32 len, u32 *cur_in)
 282 {
 283         u32 orig_in = *cur_in;
 284
 285         while (*cur_in < orig_in + len) {
 286                 struct page *cur_page;
 287                 u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
 288                                           orig_in + len - *cur_in);
 289
 290                 ASSERT(copy_len);
 291                 cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
 292
 293                 memcpy(dest + *cur_in - orig_in,
 294                         page_address(cur_page) + offset_in_page(*cur_in),
 295                         copy_len);
 296
 297                 *cur_in += copy_len;
 298         }
 299 }
 300
 301 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 302 {
 303         struct workspace *workspace = list_entry(ws, struct workspace, list);
 304         const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
 305         const u32 sectorsize = fs_info->sectorsize;
 306         int ret;
 307         /* Compressed data length, can be unaligned */
 308         u32 len_in;
 309         /* Offset inside the compressed data */
 310         u32 cur_in = 0;
 311         /* Bytes decompressed so far */
 312         u32 cur_out = 0;
 313
 314         len_in = read_compress_length(page_address(cb->compressed_pages[0]));
 315         cur_in += LZO_LEN;
 316
 317         /*
 318          * LZO header length check
 319          *
 320          * The total length should not exceed the maximum extent length,
 321          * and all sectors should be used.
 322          * If this happens, it means the compressed extent is corrupted.
 323          */
 324         if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
 325             round_up(len_in, sectorsize) < cb->compressed_len) {
 326                 btrfs_err(fs_info,
 327                         "invalid lzo header, lzo len %u compressed len %u",
 328                         len_in, cb->compressed_len);
 329                 return -EUCLEAN;
 330         }
 331
 332         /* Go through each lzo segment */
 333         while (cur_in < len_in) {
 334                 struct page *cur_page;
 335                 /* Length of the compressed segment */
 336                 u32 seg_len;
 337                 u32 sector_bytes_left;
 338                 size_t out_len = lzo1x_worst_compress(sectorsize);
 339
 340                 /*
 341                  * We should always have enough space for one segment header
 342                  * inside current sector.
 343                  */
 344                 ASSERT(cur_in / sectorsize ==
 345                        (cur_in + LZO_LEN - 1) / sectorsize);
 346                 cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
 347                 ASSERT(cur_page);
 348                 seg_len = read_compress_length(page_address(cur_page) +
 349                                                offset_in_page(cur_in));
 350                 cur_in += LZO_LEN;
 351
 352                 /* Copy the compressed segment payload into workspace */
 353                 copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
 354
 355                 /* Decompress the data */
 356                 ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
 357                                             workspace->buf, &out_len);
 358                 if (ret != LZO_E_OK) {
 359                         btrfs_err(fs_info, "failed to decompress");
 360                         ret = -EIO;
 361                         goto out;
 362                 }
 363
 364                 /* Copy the data into inode pages */
 365                 ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
 366                 cur_out += out_len;
 367
 368                 /* All data read, exit */
 369                 if (ret == 0)
 370                         goto out;
 371                 ret = 0;
 372
 373                 /* Check if the sector has enough space for a segment header */
 374                 sector_bytes_left = sectorsize - (cur_in % sectorsize);
 375                 if (sector_bytes_left >= LZO_LEN)
 376                         continue;
 377
 378                 /* Skip the padding zeros */
 379                 cur_in += sector_bytes_left;
 380         }
 381 out:
 382         if (!ret)
 383                 zero_fill_bio(cb->orig_bio);
 384         return ret;
 385 }
 386
 387 int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 388                 struct page *dest_page, unsigned long start_byte, size_t srclen,
 389                 size_t destlen)
 390 {
 391         struct workspace *workspace = list_entry(ws, struct workspace, list);
 392         size_t in_len;
 393         size_t out_len;
 394         size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
 395         int ret = 0;
 396         char *kaddr;
 397         unsigned long bytes;
 398
 399         if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
 400                 return -EUCLEAN;
 401
 402         in_len = read_compress_length(data_in);
 403         if (in_len != srclen)
 404                 return -EUCLEAN;
 405         data_in += LZO_LEN;
 406
 407         in_len = read_compress_length(data_in);
 408         if (in_len != srclen - LZO_LEN * 2) {
 409                 ret = -EUCLEAN;
 410                 goto out;
 411         }
 412         data_in += LZO_LEN;
 413
 414         out_len = PAGE_SIZE;
 415         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
 416         if (ret != LZO_E_OK) {
 417                 pr_warn("BTRFS: decompress failed!\n");
 418                 ret = -EIO;
 419                 goto out;
 420         }
 421
 422         if (out_len < start_byte) {
 423                 ret = -EIO;
 424                 goto out;
 425         }
 426
 427         /*
 428          * the caller is already checking against PAGE_SIZE, but lets
 429          * move this check closer to the memcpy/memset
 430          */
 431         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 432         bytes = min_t(unsigned long, destlen, out_len - start_byte);
 433
 434         kaddr = page_address(dest_page);
 435         memcpy(kaddr, workspace->buf + start_byte, bytes);
 436
 437         /*
 438          * btrfs_getblock is doing a zero on the tail of the page too,
 439          * but this will cover anything missing from the decompressed
 440          * data.
 441          */
 442         if (bytes < destlen)
 443                 memset(kaddr+bytes, 0, destlen-bytes);
 444 out:
 445         return ret;
 446 }
 447
 448 const struct btrfs_compress_op btrfs_lzo_compress = {
 449         .workspace_manager      = &wsm,
 450         .max_level              = 1,
 451         .default_level          = 1,
 452 };