fs/btrfs/lzo.c

   1 /*
   2  * Copyright (C) 2008 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/slab.h>
  21 #include <linux/mm.h>
  22 #include <linux/init.h>
  23 #include <linux/err.h>
  24 #include <linux/sched.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/bio.h>
  27 #include <linux/lzo.h>
  28 #include <linux/refcount.h>
  29 #include "compression.h"
  30
  31 #define LZO_LEN 4
  32
  33 struct workspace {
  34         void *mem;
  35         void *buf;      /* where decompressed data goes */
  36         void *cbuf;     /* where compressed data goes */
  37         struct list_head list;
  38 };
  39
  40 static void lzo_free_workspace(struct list_head *ws)
  41 {
  42         struct workspace *workspace = list_entry(ws, struct workspace, list);
  43
  44         kvfree(workspace->buf);
  45         kvfree(workspace->cbuf);
  46         kvfree(workspace->mem);
  47         kfree(workspace);
  48 }
  49
  50 static struct list_head *lzo_alloc_workspace(void)
  51 {
  52         struct workspace *workspace;
  53
  54         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  55         if (!workspace)
  56                 return ERR_PTR(-ENOMEM);
  57
  58         workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
  59         workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  60         workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
  61         if (!workspace->mem || !workspace->buf || !workspace->cbuf)
  62                 goto fail;
  63
  64         INIT_LIST_HEAD(&workspace->list);
  65
  66         return &workspace->list;
  67 fail:
  68         lzo_free_workspace(&workspace->list);
  69         return ERR_PTR(-ENOMEM);
  70 }
  71
  72 static inline void write_compress_length(char *buf, size_t len)
  73 {
  74         __le32 dlen;
  75
  76         dlen = cpu_to_le32(len);
  77         memcpy(buf, &dlen, LZO_LEN);
  78 }
  79
  80 static inline size_t read_compress_length(const char *buf)
  81 {
  82         __le32 dlen;
  83
  84         memcpy(&dlen, buf, LZO_LEN);
  85         return le32_to_cpu(dlen);
  86 }
  87
  88 static int lzo_compress_pages(struct list_head *ws,
  89                               struct address_space *mapping,
  90                               u64 start,
  91                               struct page **pages,
  92                               unsigned long *out_pages,
  93                               unsigned long *total_in,
  94                               unsigned long *total_out)
  95 {
  96         struct workspace *workspace = list_entry(ws, struct workspace, list);
  97         int ret = 0;
  98         char *data_in;
  99         char *cpage_out;
 100         int nr_pages = 0;
 101         struct page *in_page = NULL;
 102         struct page *out_page = NULL;
 103         unsigned long bytes_left;
 104         unsigned long len = *total_out;
 105         unsigned long nr_dest_pages = *out_pages;
 106         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 107         size_t in_len;
 108         size_t out_len;
 109         char *buf;
 110         unsigned long tot_in = 0;
 111         unsigned long tot_out = 0;
 112         unsigned long pg_bytes_left;
 113         unsigned long out_offset;
 114         unsigned long bytes;
 115
 116         *out_pages = 0;
 117         *total_out = 0;
 118         *total_in = 0;
 119
 120         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 121         data_in = kmap(in_page);
 122
 123         /*
 124          * store the size of all chunks of compressed data in
 125          * the first 4 bytes
 126          */
 127         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 128         if (out_page == NULL) {
 129                 ret = -ENOMEM;
 130                 goto out;
 131         }
 132         cpage_out = kmap(out_page);
 133         out_offset = LZO_LEN;
 134         tot_out = LZO_LEN;
 135         pages[0] = out_page;
 136         nr_pages = 1;
 137         pg_bytes_left = PAGE_SIZE - LZO_LEN;
 138
 139         /* compress at most one page of data each time */
 140         in_len = min(len, PAGE_SIZE);
 141         while (tot_in < len) {
 142                 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
 143                                        &out_len, workspace->mem);
 144                 if (ret != LZO_E_OK) {
 145                         pr_debug("BTRFS: lzo in loop returned %d\n",
 146                                ret);
 147                         ret = -EIO;
 148                         goto out;
 149                 }
 150
 151                 /* store the size of this chunk of compressed data */
 152                 write_compress_length(cpage_out + out_offset, out_len);
 153                 tot_out += LZO_LEN;
 154                 out_offset += LZO_LEN;
 155                 pg_bytes_left -= LZO_LEN;
 156
 157                 tot_in += in_len;
 158                 tot_out += out_len;
 159
 160                 /* copy bytes from the working buffer into the pages */
 161                 buf = workspace->cbuf;
 162                 while (out_len) {
 163                         bytes = min_t(unsigned long, pg_bytes_left, out_len);
 164
 165                         memcpy(cpage_out + out_offset, buf, bytes);
 166
 167                         out_len -= bytes;
 168                         pg_bytes_left -= bytes;
 169                         buf += bytes;
 170                         out_offset += bytes;
 171
 172                         /*
 173                          * we need another page for writing out.
 174                          *
 175                          * Note if there's less than 4 bytes left, we just
 176                          * skip to a new page.
 177                          */
 178                         if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
 179                             pg_bytes_left == 0) {
 180                                 if (pg_bytes_left) {
 181                                         memset(cpage_out + out_offset, 0,
 182                                                pg_bytes_left);
 183                                         tot_out += pg_bytes_left;
 184                                 }
 185
 186                                 /* we're done, don't allocate new page */
 187                                 if (out_len == 0 && tot_in >= len)
 188                                         break;
 189
 190                                 kunmap(out_page);
 191                                 if (nr_pages == nr_dest_pages) {
 192                                         out_page = NULL;
 193                                         ret = -E2BIG;
 194                                         goto out;
 195                                 }
 196
 197                                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 198                                 if (out_page == NULL) {
 199                                         ret = -ENOMEM;
 200                                         goto out;
 201                                 }
 202                                 cpage_out = kmap(out_page);
 203                                 pages[nr_pages++] = out_page;
 204
 205                                 pg_bytes_left = PAGE_SIZE;
 206                                 out_offset = 0;
 207                         }
 208                 }
 209
 210                 /* we're making it bigger, give up */
 211                 if (tot_in > 8192 && tot_in < tot_out) {
 212                         ret = -E2BIG;
 213                         goto out;
 214                 }
 215
 216                 /* we're all done */
 217                 if (tot_in >= len)
 218                         break;
 219
 220                 if (tot_out > max_out)
 221                         break;
 222
 223                 bytes_left = len - tot_in;
 224                 kunmap(in_page);
 225                 put_page(in_page);
 226
 227                 start += PAGE_SIZE;
 228                 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 229                 data_in = kmap(in_page);
 230                 in_len = min(bytes_left, PAGE_SIZE);
 231         }
 232
 233         if (tot_out >= tot_in) {
 234                 ret = -E2BIG;
 235                 goto out;
 236         }
 237
 238         /* store the size of all chunks of compressed data */
 239         cpage_out = kmap(pages[0]);
 240         write_compress_length(cpage_out, tot_out);
 241
 242         kunmap(pages[0]);
 243
 244         ret = 0;
 245         *total_out = tot_out;
 246         *total_in = tot_in;
 247 out:
 248         *out_pages = nr_pages;
 249         if (out_page)
 250                 kunmap(out_page);
 251
 252         if (in_page) {
 253                 kunmap(in_page);
 254                 put_page(in_page);
 255         }
 256
 257         return ret;
 258 }
 259
 260 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 261 {
 262         struct workspace *workspace = list_entry(ws, struct workspace, list);
 263         int ret = 0, ret2;
 264         char *data_in;
 265         unsigned long page_in_index = 0;
 266         size_t srclen = cb->compressed_len;
 267         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 268         unsigned long buf_start;
 269         unsigned long buf_offset = 0;
 270         unsigned long bytes;
 271         unsigned long working_bytes;
 272         size_t in_len;
 273         size_t out_len;
 274         unsigned long in_offset;
 275         unsigned long in_page_bytes_left;
 276         unsigned long tot_in;
 277         unsigned long tot_out;
 278         unsigned long tot_len;
 279         char *buf;
 280         bool may_late_unmap, need_unmap;
 281         struct page **pages_in = cb->compressed_pages;
 282         u64 disk_start = cb->start;
 283         struct bio *orig_bio = cb->orig_bio;
 284
 285         data_in = kmap(pages_in[0]);
 286         tot_len = read_compress_length(data_in);
 287
 288         tot_in = LZO_LEN;
 289         in_offset = LZO_LEN;
 290         tot_len = min_t(size_t, srclen, tot_len);
 291         in_page_bytes_left = PAGE_SIZE - LZO_LEN;
 292
 293         tot_out = 0;
 294
 295         while (tot_in < tot_len) {
 296                 in_len = read_compress_length(data_in + in_offset);
 297                 in_page_bytes_left -= LZO_LEN;
 298                 in_offset += LZO_LEN;
 299                 tot_in += LZO_LEN;
 300
 301                 tot_in += in_len;
 302                 working_bytes = in_len;
 303                 may_late_unmap = need_unmap = false;
 304
 305                 /* fast path: avoid using the working buffer */
 306                 if (in_page_bytes_left >= in_len) {
 307                         buf = data_in + in_offset;
 308                         bytes = in_len;
 309                         may_late_unmap = true;
 310                         goto cont;
 311                 }
 312
 313                 /* copy bytes from the pages into the working buffer */
 314                 buf = workspace->cbuf;
 315                 buf_offset = 0;
 316                 while (working_bytes) {
 317                         bytes = min(working_bytes, in_page_bytes_left);
 318
 319                         memcpy(buf + buf_offset, data_in + in_offset, bytes);
 320                         buf_offset += bytes;
 321 cont:
 322                         working_bytes -= bytes;
 323                         in_page_bytes_left -= bytes;
 324                         in_offset += bytes;
 325
 326                         /* check if we need to pick another page */
 327                         if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
 328                             || in_page_bytes_left == 0) {
 329                                 tot_in += in_page_bytes_left;
 330
 331                                 if (working_bytes == 0 && tot_in >= tot_len)
 332                                         break;
 333
 334                                 if (page_in_index + 1 >= total_pages_in) {
 335                                         ret = -EIO;
 336                                         goto done;
 337                                 }
 338
 339                                 if (may_late_unmap)
 340                                         need_unmap = true;
 341                                 else
 342                                         kunmap(pages_in[page_in_index]);
 343
 344                                 data_in = kmap(pages_in[++page_in_index]);
 345
 346                                 in_page_bytes_left = PAGE_SIZE;
 347                                 in_offset = 0;
 348                         }
 349                 }
 350
 351                 out_len = lzo1x_worst_compress(PAGE_SIZE);
 352                 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
 353                                             &out_len);
 354                 if (need_unmap)
 355                         kunmap(pages_in[page_in_index - 1]);
 356                 if (ret != LZO_E_OK) {
 357                         pr_warn("BTRFS: decompress failed\n");
 358                         ret = -EIO;
 359                         break;
 360                 }
 361
 362                 buf_start = tot_out;
 363                 tot_out += out_len;
 364
 365                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 366                                                  tot_out, disk_start, orig_bio);
 367                 if (ret2 == 0)
 368                         break;
 369         }
 370 done:
 371         kunmap(pages_in[page_in_index]);
 372         if (!ret)
 373                 zero_fill_bio(orig_bio);
 374         return ret;
 375 }
 376
 377 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 378                           struct page *dest_page,
 379                           unsigned long start_byte,
 380                           size_t srclen, size_t destlen)
 381 {
 382         struct workspace *workspace = list_entry(ws, struct workspace, list);
 383         size_t in_len;
 384         size_t out_len;
 385         size_t tot_len;
 386         int ret = 0;
 387         char *kaddr;
 388         unsigned long bytes;
 389
 390         BUG_ON(srclen < LZO_LEN);
 391
 392         tot_len = read_compress_length(data_in);
 393         data_in += LZO_LEN;
 394
 395         in_len = read_compress_length(data_in);
 396         data_in += LZO_LEN;
 397
 398         out_len = PAGE_SIZE;
 399         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
 400         if (ret != LZO_E_OK) {
 401                 pr_warn("BTRFS: decompress failed!\n");
 402                 ret = -EIO;
 403                 goto out;
 404         }
 405
 406         if (out_len < start_byte) {
 407                 ret = -EIO;
 408                 goto out;
 409         }
 410
 411         /*
 412          * the caller is already checking against PAGE_SIZE, but lets
 413          * move this check closer to the memcpy/memset
 414          */
 415         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 416         bytes = min_t(unsigned long, destlen, out_len - start_byte);
 417
 418         kaddr = kmap_atomic(dest_page);
 419         memcpy(kaddr, workspace->buf + start_byte, bytes);
 420
 421         /*
 422          * btrfs_getblock is doing a zero on the tail of the page too,
 423          * but this will cover anything missing from the decompressed
 424          * data.
 425          */
 426         if (bytes < destlen)
 427                 memset(kaddr+bytes, 0, destlen-bytes);
 428         kunmap_atomic(kaddr);
 429 out:
 430         return ret;
 431 }
 432
 433 const struct btrfs_compress_op btrfs_lzo_compress = {
 434         .alloc_workspace        = lzo_alloc_workspace,
 435         .free_workspace         = lzo_free_workspace,
 436         .compress_pages         = lzo_compress_pages,
 437         .decompress_bio         = lzo_decompress_bio,
 438         .decompress             = lzo_decompress,
 439 };