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 strm;
  37         char *buf;
  38         struct list_head list;
  39 };
  40
  41 static void zlib_free_workspace(struct list_head *ws)
  42 {
  43         struct workspace *workspace = list_entry(ws, struct workspace, list);
  44
  45         vfree(workspace->strm.workspace);
  46         kfree(workspace->buf);
  47         kfree(workspace);
  48 }
  49
  50 static struct list_head *zlib_alloc_workspace(void)
  51 {
  52         struct workspace *workspace;
  53         int workspacesize;
  54
  55         workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
  56         if (!workspace)
  57                 return ERR_PTR(-ENOMEM);
  58
  59         workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
  60                         zlib_inflate_workspacesize());
  61         workspace->strm.workspace = vmalloc(workspacesize);
  62         workspace->buf = kmalloc(PAGE_SIZE, GFP_NOFS);
  63         if (!workspace->strm.workspace || !workspace->buf)
  64                 goto fail;
  65
  66         INIT_LIST_HEAD(&workspace->list);
  67
  68         return &workspace->list;
  69 fail:
  70         zlib_free_workspace(&workspace->list);
  71         return ERR_PTR(-ENOMEM);
  72 }
  73
  74 static int zlib_compress_pages(struct list_head *ws,
  75                                struct address_space *mapping,
  76                                u64 start, unsigned long len,
  77                                struct page **pages,
  78                                unsigned long nr_dest_pages,
  79                                unsigned long *out_pages,
  80                                unsigned long *total_in,
  81                                unsigned long *total_out,
  82                                unsigned long max_out)
  83 {
  84         struct workspace *workspace = list_entry(ws, struct workspace, list);
  85         int ret;
  86         char *data_in;
  87         char *cpage_out;
  88         int nr_pages = 0;
  89         struct page *in_page = NULL;
  90         struct page *out_page = NULL;
  91         unsigned long bytes_left;
  92
  93         *out_pages = 0;
  94         *total_out = 0;
  95         *total_in = 0;
  96
  97         if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
  98                 pr_warn("BTRFS: deflateInit failed\n");
  99                 ret = -EIO;
 100                 goto out;
 101         }
 102
 103         workspace->strm.total_in = 0;
 104         workspace->strm.total_out = 0;
 105
 106         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 107         data_in = kmap(in_page);
 108
 109         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 110         if (out_page == NULL) {
 111                 ret = -ENOMEM;
 112                 goto out;
 113         }
 114         cpage_out = kmap(out_page);
 115         pages[0] = out_page;
 116         nr_pages = 1;
 117
 118         workspace->strm.next_in = data_in;
 119         workspace->strm.next_out = cpage_out;
 120         workspace->strm.avail_out = PAGE_SIZE;
 121         workspace->strm.avail_in = min(len, PAGE_SIZE);
 122
 123         while (workspace->strm.total_in < len) {
 124                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
 125                 if (ret != Z_OK) {
 126                         pr_debug("BTRFS: deflate in loop returned %d\n",
 127                                ret);
 128                         zlib_deflateEnd(&workspace->strm);
 129                         ret = -EIO;
 130                         goto out;
 131                 }
 132
 133                 /* we're making it bigger, give up */
 134                 if (workspace->strm.total_in > 8192 &&
 135                     workspace->strm.total_in <
 136                     workspace->strm.total_out) {
 137                         ret = -E2BIG;
 138                         goto out;
 139                 }
 140                 /* we need another page for writing out.  Test this
 141                  * before the total_in so we will pull in a new page for
 142                  * the stream end if required
 143                  */
 144                 if (workspace->strm.avail_out == 0) {
 145                         kunmap(out_page);
 146                         if (nr_pages == nr_dest_pages) {
 147                                 out_page = NULL;
 148                                 ret = -E2BIG;
 149                                 goto out;
 150                         }
 151                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 152                         if (out_page == NULL) {
 153                                 ret = -ENOMEM;
 154                                 goto out;
 155                         }
 156                         cpage_out = kmap(out_page);
 157                         pages[nr_pages] = out_page;
 158                         nr_pages++;
 159                         workspace->strm.avail_out = PAGE_SIZE;
 160                         workspace->strm.next_out = cpage_out;
 161                 }
 162                 /* we're all done */
 163                 if (workspace->strm.total_in >= len)
 164                         break;
 165
 166                 /* we've read in a full page, get a new one */
 167                 if (workspace->strm.avail_in == 0) {
 168                         if (workspace->strm.total_out > max_out)
 169                                 break;
 170
 171                         bytes_left = len - workspace->strm.total_in;
 172                         kunmap(in_page);
 173                         put_page(in_page);
 174
 175                         start += PAGE_SIZE;
 176                         in_page = find_get_page(mapping,
 177                                                 start >> PAGE_SHIFT);
 178                         data_in = kmap(in_page);
 179                         workspace->strm.avail_in = min(bytes_left,
 180                                                            PAGE_SIZE);
 181                         workspace->strm.next_in = data_in;
 182                 }
 183         }
 184         workspace->strm.avail_in = 0;
 185         ret = zlib_deflate(&workspace->strm, Z_FINISH);
 186         zlib_deflateEnd(&workspace->strm);
 187
 188         if (ret != Z_STREAM_END) {
 189                 ret = -EIO;
 190                 goto out;
 191         }
 192
 193         if (workspace->strm.total_out >= workspace->strm.total_in) {
 194                 ret = -E2BIG;
 195                 goto out;
 196         }
 197
 198         ret = 0;
 199         *total_out = workspace->strm.total_out;
 200         *total_in = workspace->strm.total_in;
 201 out:
 202         *out_pages = nr_pages;
 203         if (out_page)
 204                 kunmap(out_page);
 205
 206         if (in_page) {
 207                 kunmap(in_page);
 208                 put_page(in_page);
 209         }
 210         return ret;
 211 }
 212
 213 static int zlib_decompress_bio(struct list_head *ws, struct page **pages_in,
 214                                   u64 disk_start,
 215                                   struct bio *orig_bio,
 216                                   size_t srclen)
 217 {
 218         struct workspace *workspace = list_entry(ws, struct workspace, list);
 219         int ret = 0, ret2;
 220         int wbits = MAX_WBITS;
 221         char *data_in;
 222         size_t total_out = 0;
 223         unsigned long page_in_index = 0;
 224         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 225         unsigned long buf_start;
 226
 227         data_in = kmap(pages_in[page_in_index]);
 228         workspace->strm.next_in = data_in;
 229         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
 230         workspace->strm.total_in = 0;
 231
 232         workspace->strm.total_out = 0;
 233         workspace->strm.next_out = workspace->buf;
 234         workspace->strm.avail_out = PAGE_SIZE;
 235
 236         /* If it's deflate, and it's got no preset dictionary, then
 237            we can tell zlib to skip the adler32 check. */
 238         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 239             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 240             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 241
 242                 wbits = -((data_in[0] >> 4) + 8);
 243                 workspace->strm.next_in += 2;
 244                 workspace->strm.avail_in -= 2;
 245         }
 246
 247         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 248                 pr_warn("BTRFS: inflateInit failed\n");
 249                 kunmap(pages_in[page_in_index]);
 250                 return -EIO;
 251         }
 252         while (workspace->strm.total_in < srclen) {
 253                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 254                 if (ret != Z_OK && ret != Z_STREAM_END)
 255                         break;
 256
 257                 buf_start = total_out;
 258                 total_out = workspace->strm.total_out;
 259
 260                 /* we didn't make progress in this inflate call, we're done */
 261                 if (buf_start == total_out)
 262                         break;
 263
 264                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 265                                                  total_out, disk_start,
 266                                                  orig_bio);
 267                 if (ret2 == 0) {
 268                         ret = 0;
 269                         goto done;
 270                 }
 271
 272                 workspace->strm.next_out = workspace->buf;
 273                 workspace->strm.avail_out = PAGE_SIZE;
 274
 275                 if (workspace->strm.avail_in == 0) {
 276                         unsigned long tmp;
 277                         kunmap(pages_in[page_in_index]);
 278                         page_in_index++;
 279                         if (page_in_index >= total_pages_in) {
 280                                 data_in = NULL;
 281                                 break;
 282                         }
 283                         data_in = kmap(pages_in[page_in_index]);
 284                         workspace->strm.next_in = data_in;
 285                         tmp = srclen - workspace->strm.total_in;
 286                         workspace->strm.avail_in = min(tmp,
 287                                                            PAGE_SIZE);
 288                 }
 289         }
 290         if (ret != Z_STREAM_END)
 291                 ret = -EIO;
 292         else
 293                 ret = 0;
 294 done:
 295         zlib_inflateEnd(&workspace->strm);
 296         if (data_in)
 297                 kunmap(pages_in[page_in_index]);
 298         if (!ret)
 299                 zero_fill_bio(orig_bio);
 300         return ret;
 301 }
 302
 303 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 304                            struct page *dest_page,
 305                            unsigned long start_byte,
 306                            size_t srclen, size_t destlen)
 307 {
 308         struct workspace *workspace = list_entry(ws, struct workspace, list);
 309         int ret = 0;
 310         int wbits = MAX_WBITS;
 311         unsigned long bytes_left;
 312         unsigned long total_out = 0;
 313         unsigned long pg_offset = 0;
 314         char *kaddr;
 315
 316         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 317         bytes_left = destlen;
 318
 319         workspace->strm.next_in = data_in;
 320         workspace->strm.avail_in = srclen;
 321         workspace->strm.total_in = 0;
 322
 323         workspace->strm.next_out = workspace->buf;
 324         workspace->strm.avail_out = PAGE_SIZE;
 325         workspace->strm.total_out = 0;
 326         /* If it's deflate, and it's got no preset dictionary, then
 327            we can tell zlib to skip the adler32 check. */
 328         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 329             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 330             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 331
 332                 wbits = -((data_in[0] >> 4) + 8);
 333                 workspace->strm.next_in += 2;
 334                 workspace->strm.avail_in -= 2;
 335         }
 336
 337         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 338                 pr_warn("BTRFS: inflateInit failed\n");
 339                 return -EIO;
 340         }
 341
 342         while (bytes_left > 0) {
 343                 unsigned long buf_start;
 344                 unsigned long buf_offset;
 345                 unsigned long bytes;
 346
 347                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 348                 if (ret != Z_OK && ret != Z_STREAM_END)
 349                         break;
 350
 351                 buf_start = total_out;
 352                 total_out = workspace->strm.total_out;
 353
 354                 if (total_out == buf_start) {
 355                         ret = -EIO;
 356                         break;
 357                 }
 358
 359                 if (total_out <= start_byte)
 360                         goto next;
 361
 362                 if (total_out > start_byte && buf_start < start_byte)
 363                         buf_offset = start_byte - buf_start;
 364                 else
 365                         buf_offset = 0;
 366
 367                 bytes = min(PAGE_SIZE - pg_offset,
 368                             PAGE_SIZE - buf_offset);
 369                 bytes = min(bytes, bytes_left);
 370
 371                 kaddr = kmap_atomic(dest_page);
 372                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
 373                 kunmap_atomic(kaddr);
 374
 375                 pg_offset += bytes;
 376                 bytes_left -= bytes;
 377 next:
 378                 workspace->strm.next_out = workspace->buf;
 379                 workspace->strm.avail_out = PAGE_SIZE;
 380         }
 381
 382         if (ret != Z_STREAM_END && bytes_left != 0)
 383                 ret = -EIO;
 384         else
 385                 ret = 0;
 386
 387         zlib_inflateEnd(&workspace->strm);
 388
 389         /*
 390          * this should only happen if zlib returned fewer bytes than we
 391          * expected.  btrfs_get_block is responsible for zeroing from the
 392          * end of the inline extent (destlen) to the end of the page
 393          */
 394         if (pg_offset < destlen) {
 395                 kaddr = kmap_atomic(dest_page);
 396                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 397                 kunmap_atomic(kaddr);
 398         }
 399         return ret;
 400 }
 401
 402 const struct btrfs_compress_op btrfs_zlib_compress = {
 403         .alloc_workspace        = zlib_alloc_workspace,
 404         .free_workspace         = zlib_free_workspace,
 405         .compress_pages         = zlib_compress_pages,
 406         .decompress_bio         = zlib_decompress_bio,
 407         .decompress             = zlib_decompress,
 408 };