fs/btrfs/zlib.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  * Based on jffs2 zlib code:
  19  * Copyright © 2001-2007 Red Hat, Inc.
  20  * Created by David Woodhouse <dwmw2@infradead.org>
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/slab.h>
  25 #include <linux/zlib.h>
  26 #include <linux/zutil.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/init.h>
  29 #include <linux/err.h>
  30 #include <linux/sched.h>
  31 #include <linux/pagemap.h>
  32 #include <linux/bio.h>
  33 #include "compression.h"
  34
  35 struct workspace {
  36         z_stream inf_strm;
  37         z_stream def_strm;
  38         char *buf;
  39         struct list_head list;
  40 };
  41
  42 static void zlib_free_workspace(struct list_head *ws)
  43 {
  44         struct workspace *workspace = list_entry(ws, struct workspace, list);
  45
  46         vfree(workspace->def_strm.workspace);
  47         vfree(workspace->inf_strm.workspace);
  48         kfree(workspace->buf);
  49         kfree(workspace);
  50 }
  51
  52 static struct list_head *zlib_alloc_workspace(void)
  53 {
  54         struct workspace *workspace;
  55
  56         workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
  57         if (!workspace)
  58                 return ERR_PTR(-ENOMEM);
  59
  60         workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize(
  61                                                 MAX_WBITS, MAX_MEM_LEVEL));
  62         workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
  63         workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
  64         if (!workspace->def_strm.workspace ||
  65             !workspace->inf_strm.workspace || !workspace->buf)
  66                 goto fail;
  67
  68         INIT_LIST_HEAD(&workspace->list);
  69
  70         return &workspace->list;
  71 fail:
  72         zlib_free_workspace(&workspace->list);
  73         return ERR_PTR(-ENOMEM);
  74 }
  75
  76 static int zlib_compress_pages(struct list_head *ws,
  77                                struct address_space *mapping,
  78                                u64 start, unsigned long len,
  79                                struct page **pages,
  80                                unsigned long nr_dest_pages,
  81                                unsigned long *out_pages,
  82                                unsigned long *total_in,
  83                                unsigned long *total_out,
  84                                unsigned long max_out)
  85 {
  86         struct workspace *workspace = list_entry(ws, struct workspace, list);
  87         int ret;
  88         char *data_in;
  89         char *cpage_out;
  90         int nr_pages = 0;
  91         struct page *in_page = NULL;
  92         struct page *out_page = NULL;
  93         unsigned long bytes_left;
  94
  95         *out_pages = 0;
  96         *total_out = 0;
  97         *total_in = 0;
  98
  99         if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
 100                 printk(KERN_WARNING "BTRFS: deflateInit failed\n");
 101                 ret = -1;
 102                 goto out;
 103         }
 104
 105         workspace->def_strm.total_in = 0;
 106         workspace->def_strm.total_out = 0;
 107
 108         in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
 109         data_in = kmap(in_page);
 110
 111         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 112         if (out_page == NULL) {
 113                 ret = -1;
 114                 goto out;
 115         }
 116         cpage_out = kmap(out_page);
 117         pages[0] = out_page;
 118         nr_pages = 1;
 119
 120         workspace->def_strm.next_in = data_in;
 121         workspace->def_strm.next_out = cpage_out;
 122         workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
 123         workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
 124
 125         while (workspace->def_strm.total_in < len) {
 126                 ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
 127                 if (ret != Z_OK) {
 128                         printk(KERN_DEBUG "BTRFS: deflate in loop returned %d\n",
 129                                ret);
 130                         zlib_deflateEnd(&workspace->def_strm);
 131                         ret = -1;
 132                         goto out;
 133                 }
 134
 135                 /* we're making it bigger, give up */
 136                 if (workspace->def_strm.total_in > 8192 &&
 137                     workspace->def_strm.total_in <
 138                     workspace->def_strm.total_out) {
 139                         ret = -1;
 140                         goto out;
 141                 }
 142                 /* we need another page for writing out.  Test this
 143                  * before the total_in so we will pull in a new page for
 144                  * the stream end if required
 145                  */
 146                 if (workspace->def_strm.avail_out == 0) {
 147                         kunmap(out_page);
 148                         if (nr_pages == nr_dest_pages) {
 149                                 out_page = NULL;
 150                                 ret = -1;
 151                                 goto out;
 152                         }
 153                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 154                         if (out_page == NULL) {
 155                                 ret = -1;
 156                                 goto out;
 157                         }
 158                         cpage_out = kmap(out_page);
 159                         pages[nr_pages] = out_page;
 160                         nr_pages++;
 161                         workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
 162                         workspace->def_strm.next_out = cpage_out;
 163                 }
 164                 /* we're all done */
 165                 if (workspace->def_strm.total_in >= len)
 166                         break;
 167
 168                 /* we've read in a full page, get a new one */
 169                 if (workspace->def_strm.avail_in == 0) {
 170                         if (workspace->def_strm.total_out > max_out)
 171                                 break;
 172
 173                         bytes_left = len - workspace->def_strm.total_in;
 174                         kunmap(in_page);
 175                         page_cache_release(in_page);
 176
 177                         start += PAGE_CACHE_SIZE;
 178                         in_page = find_get_page(mapping,
 179                                                 start >> PAGE_CACHE_SHIFT);
 180                         data_in = kmap(in_page);
 181                         workspace->def_strm.avail_in = min(bytes_left,
 182                                                            PAGE_CACHE_SIZE);
 183                         workspace->def_strm.next_in = data_in;
 184                 }
 185         }
 186         workspace->def_strm.avail_in = 0;
 187         ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
 188         zlib_deflateEnd(&workspace->def_strm);
 189
 190         if (ret != Z_STREAM_END) {
 191                 ret = -1;
 192                 goto out;
 193         }
 194
 195         if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
 196                 ret = -1;
 197                 goto out;
 198         }
 199
 200         ret = 0;
 201         *total_out = workspace->def_strm.total_out;
 202         *total_in = workspace->def_strm.total_in;
 203 out:
 204         *out_pages = nr_pages;
 205         if (out_page)
 206                 kunmap(out_page);
 207
 208         if (in_page) {
 209                 kunmap(in_page);
 210                 page_cache_release(in_page);
 211         }
 212         return ret;
 213 }
 214
 215 static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
 216                                   u64 disk_start,
 217                                   struct bio_vec *bvec,
 218                                   int vcnt,
 219                                   size_t srclen)
 220 {
 221         struct workspace *workspace = list_entry(ws, struct workspace, list);
 222         int ret = 0, ret2;
 223         int wbits = MAX_WBITS;
 224         char *data_in;
 225         size_t total_out = 0;
 226         unsigned long page_in_index = 0;
 227         unsigned long page_out_index = 0;
 228         unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
 229                                         PAGE_CACHE_SIZE;
 230         unsigned long buf_start;
 231         unsigned long pg_offset;
 232
 233         data_in = kmap(pages_in[page_in_index]);
 234         workspace->inf_strm.next_in = data_in;
 235         workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
 236         workspace->inf_strm.total_in = 0;
 237
 238         workspace->inf_strm.total_out = 0;
 239         workspace->inf_strm.next_out = workspace->buf;
 240         workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
 241         pg_offset = 0;
 242
 243         /* If it's deflate, and it's got no preset dictionary, then
 244            we can tell zlib to skip the adler32 check. */
 245         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 246             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 247             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 248
 249                 wbits = -((data_in[0] >> 4) + 8);
 250                 workspace->inf_strm.next_in += 2;
 251                 workspace->inf_strm.avail_in -= 2;
 252         }
 253
 254         if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
 255                 printk(KERN_WARNING "BTRFS: inflateInit failed\n");
 256                 return -1;
 257         }
 258         while (workspace->inf_strm.total_in < srclen) {
 259                 ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
 260                 if (ret != Z_OK && ret != Z_STREAM_END)
 261                         break;
 262
 263                 buf_start = total_out;
 264                 total_out = workspace->inf_strm.total_out;
 265
 266                 /* we didn't make progress in this inflate call, we're done */
 267                 if (buf_start == total_out)
 268                         break;
 269
 270                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 271                                                  total_out, disk_start,
 272                                                  bvec, vcnt,
 273                                                  &page_out_index, &pg_offset);
 274                 if (ret2 == 0) {
 275                         ret = 0;
 276                         goto done;
 277                 }
 278
 279                 workspace->inf_strm.next_out = workspace->buf;
 280                 workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
 281
 282                 if (workspace->inf_strm.avail_in == 0) {
 283                         unsigned long tmp;
 284                         kunmap(pages_in[page_in_index]);
 285                         page_in_index++;
 286                         if (page_in_index >= total_pages_in) {
 287                                 data_in = NULL;
 288                                 break;
 289                         }
 290                         data_in = kmap(pages_in[page_in_index]);
 291                         workspace->inf_strm.next_in = data_in;
 292                         tmp = srclen - workspace->inf_strm.total_in;
 293                         workspace->inf_strm.avail_in = min(tmp,
 294                                                            PAGE_CACHE_SIZE);
 295                 }
 296         }
 297         if (ret != Z_STREAM_END)
 298                 ret = -1;
 299         else
 300                 ret = 0;
 301 done:
 302         zlib_inflateEnd(&workspace->inf_strm);
 303         if (data_in)
 304                 kunmap(pages_in[page_in_index]);
 305         return ret;
 306 }
 307
 308 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 309                            struct page *dest_page,
 310                            unsigned long start_byte,
 311                            size_t srclen, size_t destlen)
 312 {
 313         struct workspace *workspace = list_entry(ws, struct workspace, list);
 314         int ret = 0;
 315         int wbits = MAX_WBITS;
 316         unsigned long bytes_left = destlen;
 317         unsigned long total_out = 0;
 318         char *kaddr;
 319
 320         workspace->inf_strm.next_in = data_in;
 321         workspace->inf_strm.avail_in = srclen;
 322         workspace->inf_strm.total_in = 0;
 323
 324         workspace->inf_strm.next_out = workspace->buf;
 325         workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
 326         workspace->inf_strm.total_out = 0;
 327         /* If it's deflate, and it's got no preset dictionary, then
 328            we can tell zlib to skip the adler32 check. */
 329         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 330             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 331             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 332
 333                 wbits = -((data_in[0] >> 4) + 8);
 334                 workspace->inf_strm.next_in += 2;
 335                 workspace->inf_strm.avail_in -= 2;
 336         }
 337
 338         if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
 339                 printk(KERN_WARNING "BTRFS: inflateInit failed\n");
 340                 return -1;
 341         }
 342
 343         while (bytes_left > 0) {
 344                 unsigned long buf_start;
 345                 unsigned long buf_offset;
 346                 unsigned long bytes;
 347                 unsigned long pg_offset = 0;
 348
 349                 ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
 350                 if (ret != Z_OK && ret != Z_STREAM_END)
 351                         break;
 352
 353                 buf_start = total_out;
 354                 total_out = workspace->inf_strm.total_out;
 355
 356                 if (total_out == buf_start) {
 357                         ret = -1;
 358                         break;
 359                 }
 360
 361                 if (total_out <= start_byte)
 362                         goto next;
 363
 364                 if (total_out > start_byte && buf_start < start_byte)
 365                         buf_offset = start_byte - buf_start;
 366                 else
 367                         buf_offset = 0;
 368
 369                 bytes = min(PAGE_CACHE_SIZE - pg_offset,
 370                             PAGE_CACHE_SIZE - buf_offset);
 371                 bytes = min(bytes, bytes_left);
 372
 373                 kaddr = kmap_atomic(dest_page);
 374                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
 375                 kunmap_atomic(kaddr);
 376
 377                 pg_offset += bytes;
 378                 bytes_left -= bytes;
 379 next:
 380                 workspace->inf_strm.next_out = workspace->buf;
 381                 workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
 382         }
 383
 384         if (ret != Z_STREAM_END && bytes_left != 0)
 385                 ret = -1;
 386         else
 387                 ret = 0;
 388
 389         zlib_inflateEnd(&workspace->inf_strm);
 390         return ret;
 391 }
 392
 393 struct btrfs_compress_op btrfs_zlib_compress = {
 394         .alloc_workspace        = zlib_alloc_workspace,
 395         .free_workspace         = zlib_free_workspace,
 396         .compress_pages         = zlib_compress_pages,
 397         .decompress_biovec      = zlib_decompress_biovec,
 398         .decompress             = zlib_decompress,
 399 };