fs/btrfs/zlib.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2008 Oracle.  All rights reserved.
   4  *
   5  * Based on jffs2 zlib code:
   6  * Copyright © 2001-2007 Red Hat, Inc.
   7  * Created by David Woodhouse <dwmw2@infradead.org>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/zlib.h>
  13 #include <linux/zutil.h>
  14 #include <linux/mm.h>
  15 #include <linux/init.h>
  16 #include <linux/err.h>
  17 #include <linux/sched.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/bio.h>
  20 #include <linux/refcount.h>
  21 #include "compression.h"
  22
  23 struct workspace {
  24         z_stream strm;
  25         char *buf;
  26         struct list_head list;
  27         int level;
  28 };
  29
  30 static void zlib_free_workspace(struct list_head *ws)
  31 {
  32         struct workspace *workspace = list_entry(ws, struct workspace, list);
  33
  34         kvfree(workspace->strm.workspace);
  35         kfree(workspace->buf);
  36         kfree(workspace);
  37 }
  38
  39 static struct list_head *zlib_alloc_workspace(void)
  40 {
  41         struct workspace *workspace;
  42         int workspacesize;
  43
  44         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  45         if (!workspace)
  46                 return ERR_PTR(-ENOMEM);
  47
  48         workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
  49                         zlib_inflate_workspacesize());
  50         workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
  51         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  52         if (!workspace->strm.workspace || !workspace->buf)
  53                 goto fail;
  54
  55         INIT_LIST_HEAD(&workspace->list);
  56
  57         return &workspace->list;
  58 fail:
  59         zlib_free_workspace(&workspace->list);
  60         return ERR_PTR(-ENOMEM);
  61 }
  62
  63 static int zlib_compress_pages(struct list_head *ws,
  64                                struct address_space *mapping,
  65                                u64 start,
  66                                struct page **pages,
  67                                unsigned long *out_pages,
  68                                unsigned long *total_in,
  69                                unsigned long *total_out)
  70 {
  71         struct workspace *workspace = list_entry(ws, struct workspace, list);
  72         int ret;
  73         char *data_in;
  74         char *cpage_out;
  75         int nr_pages = 0;
  76         struct page *in_page = NULL;
  77         struct page *out_page = NULL;
  78         unsigned long bytes_left;
  79         unsigned long len = *total_out;
  80         unsigned long nr_dest_pages = *out_pages;
  81         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
  82
  83         *out_pages = 0;
  84         *total_out = 0;
  85         *total_in = 0;
  86
  87         if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
  88                 pr_warn("BTRFS: deflateInit failed\n");
  89                 ret = -EIO;
  90                 goto out;
  91         }
  92
  93         workspace->strm.total_in = 0;
  94         workspace->strm.total_out = 0;
  95
  96         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
  97         data_in = kmap(in_page);
  98
  99         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 100         if (out_page == NULL) {
 101                 ret = -ENOMEM;
 102                 goto out;
 103         }
 104         cpage_out = kmap(out_page);
 105         pages[0] = out_page;
 106         nr_pages = 1;
 107
 108         workspace->strm.next_in = data_in;
 109         workspace->strm.next_out = cpage_out;
 110         workspace->strm.avail_out = PAGE_SIZE;
 111         workspace->strm.avail_in = min(len, PAGE_SIZE);
 112
 113         while (workspace->strm.total_in < len) {
 114                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
 115                 if (ret != Z_OK) {
 116                         pr_debug("BTRFS: deflate in loop returned %d\n",
 117                                ret);
 118                         zlib_deflateEnd(&workspace->strm);
 119                         ret = -EIO;
 120                         goto out;
 121                 }
 122
 123                 /* we're making it bigger, give up */
 124                 if (workspace->strm.total_in > 8192 &&
 125                     workspace->strm.total_in <
 126                     workspace->strm.total_out) {
 127                         ret = -E2BIG;
 128                         goto out;
 129                 }
 130                 /* we need another page for writing out.  Test this
 131                  * before the total_in so we will pull in a new page for
 132                  * the stream end if required
 133                  */
 134                 if (workspace->strm.avail_out == 0) {
 135                         kunmap(out_page);
 136                         if (nr_pages == nr_dest_pages) {
 137                                 out_page = NULL;
 138                                 ret = -E2BIG;
 139                                 goto out;
 140                         }
 141                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 142                         if (out_page == NULL) {
 143                                 ret = -ENOMEM;
 144                                 goto out;
 145                         }
 146                         cpage_out = kmap(out_page);
 147                         pages[nr_pages] = out_page;
 148                         nr_pages++;
 149                         workspace->strm.avail_out = PAGE_SIZE;
 150                         workspace->strm.next_out = cpage_out;
 151                 }
 152                 /* we're all done */
 153                 if (workspace->strm.total_in >= len)
 154                         break;
 155
 156                 /* we've read in a full page, get a new one */
 157                 if (workspace->strm.avail_in == 0) {
 158                         if (workspace->strm.total_out > max_out)
 159                                 break;
 160
 161                         bytes_left = len - workspace->strm.total_in;
 162                         kunmap(in_page);
 163                         put_page(in_page);
 164
 165                         start += PAGE_SIZE;
 166                         in_page = find_get_page(mapping,
 167                                                 start >> PAGE_SHIFT);
 168                         data_in = kmap(in_page);
 169                         workspace->strm.avail_in = min(bytes_left,
 170                                                            PAGE_SIZE);
 171                         workspace->strm.next_in = data_in;
 172                 }
 173         }
 174         workspace->strm.avail_in = 0;
 175         ret = zlib_deflate(&workspace->strm, Z_FINISH);
 176         zlib_deflateEnd(&workspace->strm);
 177
 178         if (ret != Z_STREAM_END) {
 179                 ret = -EIO;
 180                 goto out;
 181         }
 182
 183         if (workspace->strm.total_out >= workspace->strm.total_in) {
 184                 ret = -E2BIG;
 185                 goto out;
 186         }
 187
 188         ret = 0;
 189         *total_out = workspace->strm.total_out;
 190         *total_in = workspace->strm.total_in;
 191 out:
 192         *out_pages = nr_pages;
 193         if (out_page)
 194                 kunmap(out_page);
 195
 196         if (in_page) {
 197                 kunmap(in_page);
 198                 put_page(in_page);
 199         }
 200         return ret;
 201 }
 202
 203 static int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 204 {
 205         struct workspace *workspace = list_entry(ws, struct workspace, list);
 206         int ret = 0, ret2;
 207         int wbits = MAX_WBITS;
 208         char *data_in;
 209         size_t total_out = 0;
 210         unsigned long page_in_index = 0;
 211         size_t srclen = cb->compressed_len;
 212         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 213         unsigned long buf_start;
 214         struct page **pages_in = cb->compressed_pages;
 215         u64 disk_start = cb->start;
 216         struct bio *orig_bio = cb->orig_bio;
 217
 218         data_in = kmap(pages_in[page_in_index]);
 219         workspace->strm.next_in = data_in;
 220         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
 221         workspace->strm.total_in = 0;
 222
 223         workspace->strm.total_out = 0;
 224         workspace->strm.next_out = workspace->buf;
 225         workspace->strm.avail_out = PAGE_SIZE;
 226
 227         /* If it's deflate, and it's got no preset dictionary, then
 228            we can tell zlib to skip the adler32 check. */
 229         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 230             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 231             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 232
 233                 wbits = -((data_in[0] >> 4) + 8);
 234                 workspace->strm.next_in += 2;
 235                 workspace->strm.avail_in -= 2;
 236         }
 237
 238         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 239                 pr_warn("BTRFS: inflateInit failed\n");
 240                 kunmap(pages_in[page_in_index]);
 241                 return -EIO;
 242         }
 243         while (workspace->strm.total_in < srclen) {
 244                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 245                 if (ret != Z_OK && ret != Z_STREAM_END)
 246                         break;
 247
 248                 buf_start = total_out;
 249                 total_out = workspace->strm.total_out;
 250
 251                 /* we didn't make progress in this inflate call, we're done */
 252                 if (buf_start == total_out)
 253                         break;
 254
 255                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
 256                                                  total_out, disk_start,
 257                                                  orig_bio);
 258                 if (ret2 == 0) {
 259                         ret = 0;
 260                         goto done;
 261                 }
 262
 263                 workspace->strm.next_out = workspace->buf;
 264                 workspace->strm.avail_out = PAGE_SIZE;
 265
 266                 if (workspace->strm.avail_in == 0) {
 267                         unsigned long tmp;
 268                         kunmap(pages_in[page_in_index]);
 269                         page_in_index++;
 270                         if (page_in_index >= total_pages_in) {
 271                                 data_in = NULL;
 272                                 break;
 273                         }
 274                         data_in = kmap(pages_in[page_in_index]);
 275                         workspace->strm.next_in = data_in;
 276                         tmp = srclen - workspace->strm.total_in;
 277                         workspace->strm.avail_in = min(tmp,
 278                                                            PAGE_SIZE);
 279                 }
 280         }
 281         if (ret != Z_STREAM_END)
 282                 ret = -EIO;
 283         else
 284                 ret = 0;
 285 done:
 286         zlib_inflateEnd(&workspace->strm);
 287         if (data_in)
 288                 kunmap(pages_in[page_in_index]);
 289         if (!ret)
 290                 zero_fill_bio(orig_bio);
 291         return ret;
 292 }
 293
 294 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 295                            struct page *dest_page,
 296                            unsigned long start_byte,
 297                            size_t srclen, size_t destlen)
 298 {
 299         struct workspace *workspace = list_entry(ws, struct workspace, list);
 300         int ret = 0;
 301         int wbits = MAX_WBITS;
 302         unsigned long bytes_left;
 303         unsigned long total_out = 0;
 304         unsigned long pg_offset = 0;
 305         char *kaddr;
 306
 307         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
 308         bytes_left = destlen;
 309
 310         workspace->strm.next_in = data_in;
 311         workspace->strm.avail_in = srclen;
 312         workspace->strm.total_in = 0;
 313
 314         workspace->strm.next_out = workspace->buf;
 315         workspace->strm.avail_out = PAGE_SIZE;
 316         workspace->strm.total_out = 0;
 317         /* If it's deflate, and it's got no preset dictionary, then
 318            we can tell zlib to skip the adler32 check. */
 319         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
 320             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
 321             !(((data_in[0]<<8) + data_in[1]) % 31)) {
 322
 323                 wbits = -((data_in[0] >> 4) + 8);
 324                 workspace->strm.next_in += 2;
 325                 workspace->strm.avail_in -= 2;
 326         }
 327
 328         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
 329                 pr_warn("BTRFS: inflateInit failed\n");
 330                 return -EIO;
 331         }
 332
 333         while (bytes_left > 0) {
 334                 unsigned long buf_start;
 335                 unsigned long buf_offset;
 336                 unsigned long bytes;
 337
 338                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
 339                 if (ret != Z_OK && ret != Z_STREAM_END)
 340                         break;
 341
 342                 buf_start = total_out;
 343                 total_out = workspace->strm.total_out;
 344
 345                 if (total_out == buf_start) {
 346                         ret = -EIO;
 347                         break;
 348                 }
 349
 350                 if (total_out <= start_byte)
 351                         goto next;
 352
 353                 if (total_out > start_byte && buf_start < start_byte)
 354                         buf_offset = start_byte - buf_start;
 355                 else
 356                         buf_offset = 0;
 357
 358                 bytes = min(PAGE_SIZE - pg_offset,
 359                             PAGE_SIZE - buf_offset);
 360                 bytes = min(bytes, bytes_left);
 361
 362                 kaddr = kmap_atomic(dest_page);
 363                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
 364                 kunmap_atomic(kaddr);
 365
 366                 pg_offset += bytes;
 367                 bytes_left -= bytes;
 368 next:
 369                 workspace->strm.next_out = workspace->buf;
 370                 workspace->strm.avail_out = PAGE_SIZE;
 371         }
 372
 373         if (ret != Z_STREAM_END && bytes_left != 0)
 374                 ret = -EIO;
 375         else
 376                 ret = 0;
 377
 378         zlib_inflateEnd(&workspace->strm);
 379
 380         /*
 381          * this should only happen if zlib returned fewer bytes than we
 382          * expected.  btrfs_get_block is responsible for zeroing from the
 383          * end of the inline extent (destlen) to the end of the page
 384          */
 385         if (pg_offset < destlen) {
 386                 kaddr = kmap_atomic(dest_page);
 387                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 388                 kunmap_atomic(kaddr);
 389         }
 390         return ret;
 391 }
 392
 393 static void zlib_set_level(struct list_head *ws, unsigned int type)
 394 {
 395         struct workspace *workspace = list_entry(ws, struct workspace, list);
 396         unsigned level = (type & 0xF0) >> 4;
 397
 398         if (level > 9)
 399                 level = 9;
 400
 401         workspace->level = level > 0 ? level : 3;
 402 }
 403
 404 const struct btrfs_compress_op btrfs_zlib_compress = {
 405         .alloc_workspace        = zlib_alloc_workspace,
 406         .free_workspace         = zlib_free_workspace,
 407         .compress_pages         = zlib_compress_pages,
 408         .decompress_bio         = zlib_decompress_bio,
 409         .decompress             = zlib_decompress,
 410         .set_level              = zlib_set_level,
 411 };