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,
  77                                struct page **pages,
  78                                unsigned long *out_pages,
  79                                unsigned long *total_in,
  80                                unsigned long *total_out)
  81 {
  82         struct workspace *workspace = list_entry(ws, struct workspace, list);
  83         int ret;
  84         char *data_in;
  85         char *cpage_out;
  86         int nr_pages = 0;
  87         struct page *in_page = NULL;
  88         struct page *out_page = NULL;
  89         unsigned long bytes_left;
  90         unsigned long len = *total_out;
  91         unsigned long nr_dest_pages = *out_pages;
  92         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
  93
  94         *out_pages = 0;
  95         *total_out = 0;
  96         *total_in = 0;
  97
  98         if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
  99                 pr_warn("BTRFS: deflateInit failed\n");
 100                 ret = -EIO;
 101                 goto out;
 102         }
 103
 104         workspace->strm.total_in = 0;
 105         workspace->strm.total_out = 0;
 106
 107         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 108         data_in = kmap(in_page);
 109
 110         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 111         if (out_page == NULL) {
 112                 ret = -ENOMEM;
 113                 goto out;
 114         }
 115         cpage_out = kmap(out_page);
 116         pages[0] = out_page;
 117         nr_pages = 1;
 118
 119         workspace->strm.next_in = data_in;
 120         workspace->strm.next_out = cpage_out;
 121         workspace->strm.avail_out = PAGE_SIZE;
 122         workspace->strm.avail_in = min(len, PAGE_SIZE);
 123
 124         while (workspace->strm.total_in < len) {
 125                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
 126                 if (ret != Z_OK) {
 127                         pr_debug("BTRFS: deflate in loop returned %d\n",
 128                                ret);
 129                         zlib_deflateEnd(&workspace->strm);
 130                         ret = -EIO;
 131                         goto out;
 132                 }
 133
 134                 /* we're making it bigger, give up */
 135                 if (workspace->strm.total_in > 8192 &&
 136                     workspace->strm.total_in <
 137                     workspace->strm.total_out) {
 138                         ret = -E2BIG;
 139                         goto out;
 140                 }
 141                 /* we need another page for writing out.  Test this
 142                  * before the total_in so we will pull in a new page for
 143                  * the stream end if required
 144                  */
 145                 if (workspace->strm.avail_out == 0) {
 146                         kunmap(out_page);
 147                         if (nr_pages == nr_dest_pages) {
 148                                 out_page = NULL;
 149                                 ret = -E2BIG;
 150                                 goto out;
 151                         }
 152                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 153                         if (out_page == NULL) {
 154                                 ret = -ENOMEM;
 155                                 goto out;
 156                         }
 157                         cpage_out = kmap(out_page);
 158                         pages[nr_pages] = out_page;
 159                         nr_pages++;
 160                         workspace->strm.avail_out = PAGE_SIZE;
 161                         workspace->strm.next_out = cpage_out;
 162                 }
 163                 /* we're all done */
 164                 if (workspace->strm.total_in >= len)
 165                         break;
 166
 167                 /* we've read in a full page, get a new one */
 168                 if (workspace->strm.avail_in == 0) {
 169                         if (workspace->strm.total_out > max_out)
 170                                 break;
 171
 172                         bytes_left = len - workspace->strm.total_in;
 173                         kunmap(in_page);
 174                         put_page(in_page);
 175
 176                         start += PAGE_SIZE;
 177                         in_page = find_get_page(mapping,
 178                                                 start >> PAGE_SHIFT);
 179                         data_in = kmap(in_page);
 180                         workspace->strm.avail_in = min(bytes_left,
 181                                                            PAGE_SIZE);
 182                         workspace->strm.next_in = data_in;
 183                 }
 184         }
 185         workspace->strm.avail_in = 0;
 186         ret = zlib_deflate(&workspace->strm, Z_FINISH);
 187         zlib_deflateEnd(&workspace->strm);
 188
 189         if (ret != Z_STREAM_END) {
 190                 ret = -EIO;
 191                 goto out;
 192         }
 193
 194         if (workspace->strm.total_out >= workspace->strm.total_in) {
 195                 ret = -E2BIG;
 196                 goto out;
 197         }
 198
 199         ret = 0;
 200         *total_out = workspace->strm.total_out;
 201         *total_in = workspace->strm.total_in;
 202 out:
 203         *out_pages = nr_pages;
 204         if (out_page)
 205                 kunmap(out_page);
 206
 207         if (in_page) {
 208                 kunmap(in_page);
 209                 put_page(in_page);
 210         }
 211         return ret;
 212 }
 213
 214 static int zlib_decompress_bio(struct list_head *ws, struct page **pages_in,
 215                                   u64 disk_start,
 216                                   struct bio *orig_bio,
 217                                   size_t srclen)
 218 {
 219         struct workspace *workspace = list_entry(ws, struct workspace, list);
 220         int ret = 0, ret2;
 221         int wbits = MAX_WBITS;
 222         char *data_in;
 223         size_t total_out = 0;
 224         unsigned long page_in_index = 0;
 225         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 226         unsigned long buf_start;
 227
 228         data_in = kmap(pages_in[page_in_index]);
 229         workspace->strm.next_in = data_in;
 230         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
 231         workspace->strm.total_in = 0;
 232
 233         workspace->strm.total_out = 0;
 234         workspace->strm.next_out = workspace->buf;
 235         workspace->strm.avail_out = PAGE_SIZE;
 236
 237         /* If it's deflate, and it's got no preset dictionary, then
 238            we can tell zlib to skip the adler32 check. */
 239         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 240             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 241             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 242
 243                 wbits = -((data_in[0] >> 4) + 8);
 244                 workspace->strm.next_in += 2;
 245                 workspace->strm.avail_in -= 2;
 246         }
 247
 248         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 249                 pr_warn("BTRFS: inflateInit failed\n");
 250                 kunmap(pages_in[page_in_index]);
 251                 return -EIO;
 252         }
 253         while (workspace->strm.total_in < srclen) {
 254                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 255                 if (ret != Z_OK && ret != Z_STREAM_END)
 256                         break;
 257
 258                 buf_start = total_out;
 259                 total_out = workspace->strm.total_out;
 260
 261                 /* we didn't make progress in this inflate call, we're done */
 262                 if (buf_start == total_out)
 263                         break;
 264
 265                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 266                                                  total_out, disk_start,
 267                                                  orig_bio);
 268                 if (ret2 == 0) {
 269                         ret = 0;
 270                         goto done;
 271                 }
 272
 273                 workspace->strm.next_out = workspace->buf;
 274                 workspace->strm.avail_out = PAGE_SIZE;
 275
 276                 if (workspace->strm.avail_in == 0) {
 277                         unsigned long tmp;
 278                         kunmap(pages_in[page_in_index]);
 279                         page_in_index++;
 280                         if (page_in_index >= total_pages_in) {
 281                                 data_in = NULL;
 282                                 break;
 283                         }
 284                         data_in = kmap(pages_in[page_in_index]);
 285                         workspace->strm.next_in = data_in;
 286                         tmp = srclen - workspace->strm.total_in;
 287                         workspace->strm.avail_in = min(tmp,
 288                                                            PAGE_SIZE);
 289                 }
 290         }
 291         if (ret != Z_STREAM_END)
 292                 ret = -EIO;
 293         else
 294                 ret = 0;
 295 done:
 296         zlib_inflateEnd(&workspace->strm);
 297         if (data_in)
 298                 kunmap(pages_in[page_in_index]);
 299         if (!ret)
 300                 zero_fill_bio(orig_bio);
 301         return ret;
 302 }
 303
 304 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 305                            struct page *dest_page,
 306                            unsigned long start_byte,
 307                            size_t srclen, size_t destlen)
 308 {
 309         struct workspace *workspace = list_entry(ws, struct workspace, list);
 310         int ret = 0;
 311         int wbits = MAX_WBITS;
 312         unsigned long bytes_left;
 313         unsigned long total_out = 0;
 314         unsigned long pg_offset = 0;
 315         char *kaddr;
 316
 317         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 318         bytes_left = destlen;
 319
 320         workspace->strm.next_in = data_in;
 321         workspace->strm.avail_in = srclen;
 322         workspace->strm.total_in = 0;
 323
 324         workspace->strm.next_out = workspace->buf;
 325         workspace->strm.avail_out = PAGE_SIZE;
 326         workspace->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->strm.next_in += 2;
 335                 workspace->strm.avail_in -= 2;
 336         }
 337
 338         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 339                 pr_warn("BTRFS: inflateInit failed\n");
 340                 return -EIO;
 341         }
 342
 343         while (bytes_left > 0) {
 344                 unsigned long buf_start;
 345                 unsigned long buf_offset;
 346                 unsigned long bytes;
 347
 348                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 349                 if (ret != Z_OK && ret != Z_STREAM_END)
 350                         break;
 351
 352                 buf_start = total_out;
 353                 total_out = workspace->strm.total_out;
 354
 355                 if (total_out == buf_start) {
 356                         ret = -EIO;
 357                         break;
 358                 }
 359
 360                 if (total_out <= start_byte)
 361                         goto next;
 362
 363                 if (total_out > start_byte && buf_start < start_byte)
 364                         buf_offset = start_byte - buf_start;
 365                 else
 366                         buf_offset = 0;
 367
 368                 bytes = min(PAGE_SIZE - pg_offset,
 369                             PAGE_SIZE - buf_offset);
 370                 bytes = min(bytes, bytes_left);
 371
 372                 kaddr = kmap_atomic(dest_page);
 373                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
 374                 kunmap_atomic(kaddr);
 375
 376                 pg_offset += bytes;
 377                 bytes_left -= bytes;
 378 next:
 379                 workspace->strm.next_out = workspace->buf;
 380                 workspace->strm.avail_out = PAGE_SIZE;
 381         }
 382
 383         if (ret != Z_STREAM_END && bytes_left != 0)
 384                 ret = -EIO;
 385         else
 386                 ret = 0;
 387
 388         zlib_inflateEnd(&workspace->strm);
 389
 390         /*
 391          * this should only happen if zlib returned fewer bytes than we
 392          * expected.  btrfs_get_block is responsible for zeroing from the
 393          * end of the inline extent (destlen) to the end of the page
 394          */
 395         if (pg_offset < destlen) {
 396                 kaddr = kmap_atomic(dest_page);
 397                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 398                 kunmap_atomic(kaddr);
 399         }
 400         return ret;
 401 }
 402
 403 const struct btrfs_compress_op btrfs_zlib_compress = {
 404         .alloc_workspace        = zlib_alloc_workspace,
 405         .free_workspace         = zlib_free_workspace,
 406         .compress_pages         = zlib_compress_pages,
 407         .decompress_bio         = zlib_decompress_bio,
 408         .decompress             = zlib_decompress,
 409 };