fs/btrfs/zstd.c

   1 /*
   2  * Copyright (c) 2016-present, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public
   7  * License v2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  */
  14 #include <linux/bio.h>
  15 #include <linux/err.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/refcount.h>
  21 #include <linux/sched.h>
  22 #include <linux/slab.h>
  23 #include <linux/zstd.h>
  24 #include "compression.h"
  25
  26 #define ZSTD_BTRFS_MAX_WINDOWLOG 17
  27 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
  28 #define ZSTD_BTRFS_DEFAULT_LEVEL 3
  29
  30 static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
  31 {
  32         ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
  33                                                 src_len, 0);
  34
  35         if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
  36                 params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
  37         WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
  38         return params;
  39 }
  40
  41 struct workspace {
  42         void *mem;
  43         size_t size;
  44         char *buf;
  45         struct list_head list;
  46 };
  47
  48 static void zstd_free_workspace(struct list_head *ws)
  49 {
  50         struct workspace *workspace = list_entry(ws, struct workspace, list);
  51
  52         kvfree(workspace->mem);
  53         kfree(workspace->buf);
  54         kfree(workspace);
  55 }
  56
  57 static struct list_head *zstd_alloc_workspace(void)
  58 {
  59         ZSTD_parameters params =
  60                         zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
  61         struct workspace *workspace;
  62
  63         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  64         if (!workspace)
  65                 return ERR_PTR(-ENOMEM);
  66
  67         workspace->size = max_t(size_t,
  68                         ZSTD_CStreamWorkspaceBound(params.cParams),
  69                         ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
  70         workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
  71         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  72         if (!workspace->mem || !workspace->buf)
  73                 goto fail;
  74
  75         INIT_LIST_HEAD(&workspace->list);
  76
  77         return &workspace->list;
  78 fail:
  79         zstd_free_workspace(&workspace->list);
  80         return ERR_PTR(-ENOMEM);
  81 }
  82
  83 static int zstd_compress_pages(struct list_head *ws,
  84                 struct address_space *mapping,
  85                 u64 start,
  86                 struct page **pages,
  87                 unsigned long *out_pages,
  88                 unsigned long *total_in,
  89                 unsigned long *total_out)
  90 {
  91         struct workspace *workspace = list_entry(ws, struct workspace, list);
  92         ZSTD_CStream *stream;
  93         int ret = 0;
  94         int nr_pages = 0;
  95         struct page *in_page = NULL;  /* The current page to read */
  96         struct page *out_page = NULL; /* The current page to write to */
  97         ZSTD_inBuffer in_buf = { NULL, 0, 0 };
  98         ZSTD_outBuffer out_buf = { NULL, 0, 0 };
  99         unsigned long tot_in = 0;
 100         unsigned long tot_out = 0;
 101         unsigned long len = *total_out;
 102         const unsigned long nr_dest_pages = *out_pages;
 103         unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 104         ZSTD_parameters params = zstd_get_btrfs_parameters(len);
 105
 106         *out_pages = 0;
 107         *total_out = 0;
 108         *total_in = 0;
 109
 110         /* Initialize the stream */
 111         stream = ZSTD_initCStream(params, len, workspace->mem,
 112                         workspace->size);
 113         if (!stream) {
 114                 pr_warn("BTRFS: ZSTD_initCStream failed\n");
 115                 ret = -EIO;
 116                 goto out;
 117         }
 118
 119         /* map in the first page of input data */
 120         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 121         in_buf.src = kmap(in_page);
 122         in_buf.pos = 0;
 123         in_buf.size = min_t(size_t, len, PAGE_SIZE);
 124
 125
 126         /* Allocate and map in the output buffer */
 127         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 128         if (out_page == NULL) {
 129                 ret = -ENOMEM;
 130                 goto out;
 131         }
 132         pages[nr_pages++] = out_page;
 133         out_buf.dst = kmap(out_page);
 134         out_buf.pos = 0;
 135         out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 136
 137         while (1) {
 138                 size_t ret2;
 139
 140                 ret2 = ZSTD_compressStream(stream, &out_buf, &in_buf);
 141                 if (ZSTD_isError(ret2)) {
 142                         pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
 143                                         ZSTD_getErrorCode(ret2));
 144                         ret = -EIO;
 145                         goto out;
 146                 }
 147
 148                 /* Check to see if we are making it bigger */
 149                 if (tot_in + in_buf.pos > 8192 &&
 150                                 tot_in + in_buf.pos <
 151                                 tot_out + out_buf.pos) {
 152                         ret = -E2BIG;
 153                         goto out;
 154                 }
 155
 156                 /* We've reached the end of our output range */
 157                 if (out_buf.pos >= max_out) {
 158                         tot_out += out_buf.pos;
 159                         ret = -E2BIG;
 160                         goto out;
 161                 }
 162
 163                 /* Check if we need more output space */
 164                 if (out_buf.pos == out_buf.size) {
 165                         tot_out += PAGE_SIZE;
 166                         max_out -= PAGE_SIZE;
 167                         kunmap(out_page);
 168                         if (nr_pages == nr_dest_pages) {
 169                                 out_page = NULL;
 170                                 ret = -E2BIG;
 171                                 goto out;
 172                         }
 173                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 174                         if (out_page == NULL) {
 175                                 ret = -ENOMEM;
 176                                 goto out;
 177                         }
 178                         pages[nr_pages++] = out_page;
 179                         out_buf.dst = kmap(out_page);
 180                         out_buf.pos = 0;
 181                         out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 182                 }
 183
 184                 /* We've reached the end of the input */
 185                 if (in_buf.pos >= len) {
 186                         tot_in += in_buf.pos;
 187                         break;
 188                 }
 189
 190                 /* Check if we need more input */
 191                 if (in_buf.pos == in_buf.size) {
 192                         tot_in += PAGE_SIZE;
 193                         kunmap(in_page);
 194                         put_page(in_page);
 195
 196                         start += PAGE_SIZE;
 197                         len -= PAGE_SIZE;
 198                         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 199                         in_buf.src = kmap(in_page);
 200                         in_buf.pos = 0;
 201                         in_buf.size = min_t(size_t, len, PAGE_SIZE);
 202                 }
 203         }
 204         while (1) {
 205                 size_t ret2;
 206
 207                 ret2 = ZSTD_endStream(stream, &out_buf);
 208                 if (ZSTD_isError(ret2)) {
 209                         pr_debug("BTRFS: ZSTD_endStream returned %d\n",
 210                                         ZSTD_getErrorCode(ret2));
 211                         ret = -EIO;
 212                         goto out;
 213                 }
 214                 if (ret2 == 0) {
 215                         tot_out += out_buf.pos;
 216                         break;
 217                 }
 218                 if (out_buf.pos >= max_out) {
 219                         tot_out += out_buf.pos;
 220                         ret = -E2BIG;
 221                         goto out;
 222                 }
 223
 224                 tot_out += PAGE_SIZE;
 225                 max_out -= PAGE_SIZE;
 226                 kunmap(out_page);
 227                 if (nr_pages == nr_dest_pages) {
 228                         out_page = NULL;
 229                         ret = -E2BIG;
 230                         goto out;
 231                 }
 232                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 233                 if (out_page == NULL) {
 234                         ret = -ENOMEM;
 235                         goto out;
 236                 }
 237                 pages[nr_pages++] = out_page;
 238                 out_buf.dst = kmap(out_page);
 239                 out_buf.pos = 0;
 240                 out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 241         }
 242
 243         if (tot_out >= tot_in) {
 244                 ret = -E2BIG;
 245                 goto out;
 246         }
 247
 248         ret = 0;
 249         *total_in = tot_in;
 250         *total_out = tot_out;
 251 out:
 252         *out_pages = nr_pages;
 253         /* Cleanup */
 254         if (in_page) {
 255                 kunmap(in_page);
 256                 put_page(in_page);
 257         }
 258         if (out_page)
 259                 kunmap(out_page);
 260         return ret;
 261 }
 262
 263 static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 264 {
 265         struct workspace *workspace = list_entry(ws, struct workspace, list);
 266         struct page **pages_in = cb->compressed_pages;
 267         u64 disk_start = cb->start;
 268         struct bio *orig_bio = cb->orig_bio;
 269         size_t srclen = cb->compressed_len;
 270         ZSTD_DStream *stream;
 271         int ret = 0;
 272         unsigned long page_in_index = 0;
 273         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 274         unsigned long buf_start;
 275         unsigned long total_out = 0;
 276         ZSTD_inBuffer in_buf = { NULL, 0, 0 };
 277         ZSTD_outBuffer out_buf = { NULL, 0, 0 };
 278
 279         stream = ZSTD_initDStream(
 280                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 281         if (!stream) {
 282                 pr_debug("BTRFS: ZSTD_initDStream failed\n");
 283                 ret = -EIO;
 284                 goto done;
 285         }
 286
 287         in_buf.src = kmap(pages_in[page_in_index]);
 288         in_buf.pos = 0;
 289         in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 290
 291         out_buf.dst = workspace->buf;
 292         out_buf.pos = 0;
 293         out_buf.size = PAGE_SIZE;
 294
 295         while (1) {
 296                 size_t ret2;
 297
 298                 ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
 299                 if (ZSTD_isError(ret2)) {
 300                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 301                                         ZSTD_getErrorCode(ret2));
 302                         ret = -EIO;
 303                         goto done;
 304                 }
 305                 buf_start = total_out;
 306                 total_out += out_buf.pos;
 307                 out_buf.pos = 0;
 308
 309                 ret = btrfs_decompress_buf2page(out_buf.dst, buf_start,
 310                                 total_out, disk_start, orig_bio);
 311                 if (ret == 0)
 312                         break;
 313
 314                 if (in_buf.pos >= srclen)
 315                         break;
 316
 317                 /* Check if we've hit the end of a frame */
 318                 if (ret2 == 0)
 319                         break;
 320
 321                 if (in_buf.pos == in_buf.size) {
 322                         kunmap(pages_in[page_in_index++]);
 323                         if (page_in_index >= total_pages_in) {
 324                                 in_buf.src = NULL;
 325                                 ret = -EIO;
 326                                 goto done;
 327                         }
 328                         srclen -= PAGE_SIZE;
 329                         in_buf.src = kmap(pages_in[page_in_index]);
 330                         in_buf.pos = 0;
 331                         in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 332                 }
 333         }
 334         ret = 0;
 335         zero_fill_bio(orig_bio);
 336 done:
 337         if (in_buf.src)
 338                 kunmap(pages_in[page_in_index]);
 339         return ret;
 340 }
 341
 342 static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 343                 struct page *dest_page,
 344                 unsigned long start_byte,
 345                 size_t srclen, size_t destlen)
 346 {
 347         struct workspace *workspace = list_entry(ws, struct workspace, list);
 348         ZSTD_DStream *stream;
 349         int ret = 0;
 350         size_t ret2;
 351         ZSTD_inBuffer in_buf = { NULL, 0, 0 };
 352         ZSTD_outBuffer out_buf = { NULL, 0, 0 };
 353         unsigned long total_out = 0;
 354         unsigned long pg_offset = 0;
 355         char *kaddr;
 356
 357         stream = ZSTD_initDStream(
 358                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 359         if (!stream) {
 360                 pr_warn("BTRFS: ZSTD_initDStream failed\n");
 361                 ret = -EIO;
 362                 goto finish;
 363         }
 364
 365         destlen = min_t(size_t, destlen, PAGE_SIZE);
 366
 367         in_buf.src = data_in;
 368         in_buf.pos = 0;
 369         in_buf.size = srclen;
 370
 371         out_buf.dst = workspace->buf;
 372         out_buf.pos = 0;
 373         out_buf.size = PAGE_SIZE;
 374
 375         ret2 = 1;
 376         while (pg_offset < destlen && in_buf.pos < in_buf.size) {
 377                 unsigned long buf_start;
 378                 unsigned long buf_offset;
 379                 unsigned long bytes;
 380
 381                 /* Check if the frame is over and we still need more input */
 382                 if (ret2 == 0) {
 383                         pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
 384                         ret = -EIO;
 385                         goto finish;
 386                 }
 387                 ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
 388                 if (ZSTD_isError(ret2)) {
 389                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 390                                         ZSTD_getErrorCode(ret2));
 391                         ret = -EIO;
 392                         goto finish;
 393                 }
 394
 395                 buf_start = total_out;
 396                 total_out += out_buf.pos;
 397                 out_buf.pos = 0;
 398
 399                 if (total_out <= start_byte)
 400                         continue;
 401
 402                 if (total_out > start_byte && buf_start < start_byte)
 403                         buf_offset = start_byte - buf_start;
 404                 else
 405                         buf_offset = 0;
 406
 407                 bytes = min_t(unsigned long, destlen - pg_offset,
 408                                 out_buf.size - buf_offset);
 409
 410                 kaddr = kmap_atomic(dest_page);
 411                 memcpy(kaddr + pg_offset, out_buf.dst + buf_offset, bytes);
 412                 kunmap_atomic(kaddr);
 413
 414                 pg_offset += bytes;
 415         }
 416         ret = 0;
 417 finish:
 418         if (pg_offset < destlen) {
 419                 kaddr = kmap_atomic(dest_page);
 420                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 421                 kunmap_atomic(kaddr);
 422         }
 423         return ret;
 424 }
 425
 426 const struct btrfs_compress_op btrfs_zstd_compress = {
 427         .alloc_workspace = zstd_alloc_workspace,
 428         .free_workspace = zstd_free_workspace,
 429         .compress_pages = zstd_compress_pages,
 430         .decompress_bio = zstd_decompress_bio,
 431         .decompress = zstd_decompress,
 432 };