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 void lzo_free_workspace(struct list_head *ws)
  67 {
  68         struct workspace *workspace = list_entry(ws, struct workspace, list);
  69
  70         kvfree(workspace->buf);
  71         kvfree(workspace->cbuf);
  72         kvfree(workspace->mem);
  73         kfree(workspace);
  74 }
  75
  76 struct list_head *lzo_alloc_workspace(unsigned int level)
  77 {
  78         struct workspace *workspace;
  79
  80         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  81         if (!workspace)
  82                 return ERR_PTR(-ENOMEM);
  83
  84         workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
  85         workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  86         workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  87         if (!workspace->mem || !workspace->buf || !workspace->cbuf)
  88                 goto fail;
  89
  90         INIT_LIST_HEAD(&workspace->list);
  91
  92         return &workspace->list;
  93 fail:
  94         lzo_free_workspace(&workspace->list);
  95         return ERR_PTR(-ENOMEM);
  96 }
  97
  98 static inline void write_compress_length(char *buf, size_t len)
  99 {
 100         __le32 dlen;
 101
 102         dlen = cpu_to_le32(len);
 103         memcpy(buf, &dlen, LZO_LEN);
 104 }
 105
 106 static inline size_t read_compress_length(const char *buf)
 107 {
 108         __le32 dlen;
 109
 110         memcpy(&dlen, buf, LZO_LEN);
 111         return le32_to_cpu(dlen);
 112 }
 113
 114 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
 115                 u64 start, struct page **pages, unsigned long *out_pages,
 116                 unsigned long *total_in, unsigned long *total_out)
 117 {
 118         struct workspace *workspace = list_entry(ws, struct workspace, list);
 119         int ret = 0;
 120         char *data_in;
 121         char *cpage_out;
 122         int nr_pages = 0;
 123         struct page *in_page = NULL;
 124         struct page *out_page = NULL;
 125         unsigned long bytes_left;
 126         unsigned long len = *total_out;
 127         unsigned long nr_dest_pages = *out_pages;
 128         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 129         size_t in_len;
 130         size_t out_len;
 131         char *buf;
 132         unsigned long tot_in = 0;
 133         unsigned long tot_out = 0;
 134         unsigned long pg_bytes_left;
 135         unsigned long out_offset;
 136         unsigned long bytes;
 137
 138         *out_pages = 0;
 139         *total_out = 0;
 140         *total_in = 0;
 141
 142         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 143         data_in = kmap(in_page);
 144
 145         /*
 146          * store the size of all chunks of compressed data in
 147          * the first 4 bytes
 148          */
 149         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 150         if (out_page == NULL) {
 151                 ret = -ENOMEM;
 152                 goto out;
 153         }
 154         cpage_out = kmap(out_page);
 155         out_offset = LZO_LEN;
 156         tot_out = LZO_LEN;
 157         pages[0] = out_page;
 158         nr_pages = 1;
 159         pg_bytes_left = PAGE_SIZE - LZO_LEN;
 160
 161         /* compress at most one page of data each time */
 162         in_len = min(len, PAGE_SIZE);
 163         while (tot_in < len) {
 164                 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
 165                                        &out_len, workspace->mem);
 166                 if (ret != LZO_E_OK) {
 167                         pr_debug("BTRFS: lzo in loop returned %d\n",
 168                                ret);
 169                         ret = -EIO;
 170                         goto out;
 171                 }
 172
 173                 /* store the size of this chunk of compressed data */
 174                 write_compress_length(cpage_out + out_offset, out_len);
 175                 tot_out += LZO_LEN;
 176                 out_offset += LZO_LEN;
 177                 pg_bytes_left -= LZO_LEN;
 178
 179                 tot_in += in_len;
 180                 tot_out += out_len;
 181
 182                 /* copy bytes from the working buffer into the pages */
 183                 buf = workspace->cbuf;
 184                 while (out_len) {
 185                         bytes = min_t(unsigned long, pg_bytes_left, out_len);
 186
 187                         memcpy(cpage_out + out_offset, buf, bytes);
 188
 189                         out_len -= bytes;
 190                         pg_bytes_left -= bytes;
 191                         buf += bytes;
 192                         out_offset += bytes;
 193
 194                         /*
 195                          * we need another page for writing out.
 196                          *
 197                          * Note if there's less than 4 bytes left, we just
 198                          * skip to a new page.
 199                          */
 200                         if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
 201                             pg_bytes_left == 0) {
 202                                 if (pg_bytes_left) {
 203                                         memset(cpage_out + out_offset, 0,
 204                                                pg_bytes_left);
 205                                         tot_out += pg_bytes_left;
 206                                 }
 207
 208                                 /* we're done, don't allocate new page */
 209                                 if (out_len == 0 && tot_in >= len)
 210                                         break;
 211
 212                                 kunmap(out_page);
 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 | __GFP_HIGHMEM);
 220                                 if (out_page == NULL) {
 221                                         ret = -ENOMEM;
 222                                         goto out;
 223                                 }
 224                                 cpage_out = kmap(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                 kunmap(in_page);
 247                 put_page(in_page);
 248
 249                 start += PAGE_SIZE;
 250                 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 251                 data_in = kmap(in_page);
 252                 in_len = min(bytes_left, PAGE_SIZE);
 253         }
 254
 255         if (tot_out >= tot_in) {
 256                 ret = -E2BIG;
 257                 goto out;
 258         }
 259
 260         /* store the size of all chunks of compressed data */
 261         cpage_out = kmap(pages[0]);
 262         write_compress_length(cpage_out, tot_out);
 263
 264         kunmap(pages[0]);
 265
 266         ret = 0;
 267         *total_out = tot_out;
 268         *total_in = tot_in;
 269 out:
 270         *out_pages = nr_pages;
 271         if (out_page)
 272                 kunmap(out_page);
 273
 274         if (in_page) {
 275                 kunmap(in_page);
 276                 put_page(in_page);
 277         }
 278
 279         return ret;
 280 }
 281
 282 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 283 {
 284         struct workspace *workspace = list_entry(ws, struct workspace, list);
 285         int ret = 0, ret2;
 286         char *data_in;
 287         unsigned long page_in_index = 0;
 288         size_t srclen = cb->compressed_len;
 289         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 290         unsigned long buf_start;
 291         unsigned long buf_offset = 0;
 292         unsigned long bytes;
 293         unsigned long working_bytes;
 294         size_t in_len;
 295         size_t out_len;
 296         const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
 297         unsigned long in_offset;
 298         unsigned long in_page_bytes_left;
 299         unsigned long tot_in;
 300         unsigned long tot_out;
 301         unsigned long tot_len;
 302         char *buf;
 303         bool may_late_unmap, need_unmap;
 304         struct page **pages_in = cb->compressed_pages;
 305         u64 disk_start = cb->start;
 306         struct bio *orig_bio = cb->orig_bio;
 307
 308         data_in = kmap(pages_in[0]);
 309         tot_len = read_compress_length(data_in);
 310         /*
 311          * Compressed data header check.
 312          *
 313          * The real compressed size can't exceed the maximum extent length, and
 314          * all pages should be used (whole unused page with just the segment
 315          * header is not possible).  If this happens it means the compressed
 316          * extent is corrupted.
 317          */
 318         if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
 319             tot_len < srclen - PAGE_SIZE) {
 320                 ret = -EUCLEAN;
 321                 goto done;
 322         }
 323
 324         tot_in = LZO_LEN;
 325         in_offset = LZO_LEN;
 326         in_page_bytes_left = PAGE_SIZE - LZO_LEN;
 327
 328         tot_out = 0;
 329
 330         while (tot_in < tot_len) {
 331                 in_len = read_compress_length(data_in + in_offset);
 332                 in_page_bytes_left -= LZO_LEN;
 333                 in_offset += LZO_LEN;
 334                 tot_in += LZO_LEN;
 335
 336                 /*
 337                  * Segment header check.
 338                  *
 339                  * The segment length must not exceed the maximum LZO
 340                  * compression size, nor the total compressed size.
 341                  */
 342                 if (in_len > max_segment_len || tot_in + in_len > tot_len) {
 343                         ret = -EUCLEAN;
 344                         goto done;
 345                 }
 346
 347                 tot_in += in_len;
 348                 working_bytes = in_len;
 349                 may_late_unmap = need_unmap = false;
 350
 351                 /* fast path: avoid using the working buffer */
 352                 if (in_page_bytes_left >= in_len) {
 353                         buf = data_in + in_offset;
 354                         bytes = in_len;
 355                         may_late_unmap = true;
 356                         goto cont;
 357                 }
 358
 359                 /* copy bytes from the pages into the working buffer */
 360                 buf = workspace->cbuf;
 361                 buf_offset = 0;
 362                 while (working_bytes) {
 363                         bytes = min(working_bytes, in_page_bytes_left);
 364
 365                         memcpy(buf + buf_offset, data_in + in_offset, bytes);
 366                         buf_offset += bytes;
 367 cont:
 368                         working_bytes -= bytes;
 369                         in_page_bytes_left -= bytes;
 370                         in_offset += bytes;
 371
 372                         /* check if we need to pick another page */
 373                         if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
 374                             || in_page_bytes_left == 0) {
 375                                 tot_in += in_page_bytes_left;
 376
 377                                 if (working_bytes == 0 && tot_in >= tot_len)
 378                                         break;
 379
 380                                 if (page_in_index + 1 >= total_pages_in) {
 381                                         ret = -EIO;
 382                                         goto done;
 383                                 }
 384
 385                                 if (may_late_unmap)
 386                                         need_unmap = true;
 387                                 else
 388                                         kunmap(pages_in[page_in_index]);
 389
 390                                 data_in = kmap(pages_in[++page_in_index]);
 391
 392                                 in_page_bytes_left = PAGE_SIZE;
 393                                 in_offset = 0;
 394                         }
 395                 }
 396
 397                 out_len = max_segment_len;
 398                 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
 399                                             &out_len);
 400                 if (need_unmap)
 401                         kunmap(pages_in[page_in_index - 1]);
 402                 if (ret != LZO_E_OK) {
 403                         pr_warn("BTRFS: decompress failed\n");
 404                         ret = -EIO;
 405                         break;
 406                 }
 407
 408                 buf_start = tot_out;
 409                 tot_out += out_len;
 410
 411                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 412                                                  tot_out, disk_start, orig_bio);
 413                 if (ret2 == 0)
 414                         break;
 415         }
 416 done:
 417         kunmap(pages_in[page_in_index]);
 418         if (!ret)
 419                 zero_fill_bio(orig_bio);
 420         return ret;
 421 }
 422
 423 int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 424                 struct page *dest_page, unsigned long start_byte, size_t srclen,
 425                 size_t destlen)
 426 {
 427         struct workspace *workspace = list_entry(ws, struct workspace, list);
 428         size_t in_len;
 429         size_t out_len;
 430         size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
 431         int ret = 0;
 432         char *kaddr;
 433         unsigned long bytes;
 434
 435         if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
 436                 return -EUCLEAN;
 437
 438         in_len = read_compress_length(data_in);
 439         if (in_len != srclen)
 440                 return -EUCLEAN;
 441         data_in += LZO_LEN;
 442
 443         in_len = read_compress_length(data_in);
 444         if (in_len != srclen - LZO_LEN * 2) {
 445                 ret = -EUCLEAN;
 446                 goto out;
 447         }
 448         data_in += LZO_LEN;
 449
 450         out_len = PAGE_SIZE;
 451         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
 452         if (ret != LZO_E_OK) {
 453                 pr_warn("BTRFS: decompress failed!\n");
 454                 ret = -EIO;
 455                 goto out;
 456         }
 457
 458         if (out_len < start_byte) {
 459                 ret = -EIO;
 460                 goto out;
 461         }
 462
 463         /*
 464          * the caller is already checking against PAGE_SIZE, but lets
 465          * move this check closer to the memcpy/memset
 466          */
 467         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 468         bytes = min_t(unsigned long, destlen, out_len - start_byte);
 469
 470         kaddr = kmap_atomic(dest_page);
 471         memcpy(kaddr, workspace->buf + start_byte, bytes);
 472
 473         /*
 474          * btrfs_getblock is doing a zero on the tail of the page too,
 475          * but this will cover anything missing from the decompressed
 476          * data.
 477          */
 478         if (bytes < destlen)
 479                 memset(kaddr+bytes, 0, destlen-bytes);
 480         kunmap_atomic(kaddr);
 481 out:
 482         return ret;
 483 }
 484
 485 const struct btrfs_compress_op btrfs_lzo_compress = {
 486         .workspace_manager      = &wsm,
 487         .max_level              = 1,
 488         .default_level          = 1,
 489 };