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         ZSTD_inBuffer in_buf;
  47         ZSTD_outBuffer out_buf;
  48 };
  49
  50 static void zstd_free_workspace(struct list_head *ws)
  51 {
  52         struct workspace *workspace = list_entry(ws, struct workspace, list);
  53
  54         kvfree(workspace->mem);
  55         kfree(workspace->buf);
  56         kfree(workspace);
  57 }
  58
  59 static struct list_head *zstd_alloc_workspace(void)
  60 {
  61         ZSTD_parameters params =
  62                         zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
  63         struct workspace *workspace;
  64
  65         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  66         if (!workspace)
  67                 return ERR_PTR(-ENOMEM);
  68
  69         workspace->size = max_t(size_t,
  70                         ZSTD_CStreamWorkspaceBound(params.cParams),
  71                         ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
  72         workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
  73         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  74         if (!workspace->mem || !workspace->buf)
  75                 goto fail;
  76
  77         INIT_LIST_HEAD(&workspace->list);
  78
  79         return &workspace->list;
  80 fail:
  81         zstd_free_workspace(&workspace->list);
  82         return ERR_PTR(-ENOMEM);
  83 }
  84
  85 static int zstd_compress_pages(struct list_head *ws,
  86                 struct address_space *mapping,
  87                 u64 start,
  88                 struct page **pages,
  89                 unsigned long *out_pages,
  90                 unsigned long *total_in,
  91                 unsigned long *total_out)
  92 {
  93         struct workspace *workspace = list_entry(ws, struct workspace, list);
  94         ZSTD_CStream *stream;
  95         int ret = 0;
  96         int nr_pages = 0;
  97         struct page *in_page = NULL;  /* The current page to read */
  98         struct page *out_page = NULL; /* The current page to write to */
  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         workspace->in_buf.src = kmap(in_page);
 122         workspace->in_buf.pos = 0;
 123         workspace->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         workspace->out_buf.dst = kmap(out_page);
 134         workspace->out_buf.pos = 0;
 135         workspace->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, &workspace->out_buf,
 141                                 &workspace->in_buf);
 142                 if (ZSTD_isError(ret2)) {
 143                         pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
 144                                         ZSTD_getErrorCode(ret2));
 145                         ret = -EIO;
 146                         goto out;
 147                 }
 148
 149                 /* Check to see if we are making it bigger */
 150                 if (tot_in + workspace->in_buf.pos > 8192 &&
 151                                 tot_in + workspace->in_buf.pos <
 152                                 tot_out + workspace->out_buf.pos) {
 153                         ret = -E2BIG;
 154                         goto out;
 155                 }
 156
 157                 /* We've reached the end of our output range */
 158                 if (workspace->out_buf.pos >= max_out) {
 159                         tot_out += workspace->out_buf.pos;
 160                         ret = -E2BIG;
 161                         goto out;
 162                 }
 163
 164                 /* Check if we need more output space */
 165                 if (workspace->out_buf.pos == workspace->out_buf.size) {
 166                         tot_out += PAGE_SIZE;
 167                         max_out -= PAGE_SIZE;
 168                         kunmap(out_page);
 169                         if (nr_pages == nr_dest_pages) {
 170                                 out_page = NULL;
 171                                 ret = -E2BIG;
 172                                 goto out;
 173                         }
 174                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 175                         if (out_page == NULL) {
 176                                 ret = -ENOMEM;
 177                                 goto out;
 178                         }
 179                         pages[nr_pages++] = out_page;
 180                         workspace->out_buf.dst = kmap(out_page);
 181                         workspace->out_buf.pos = 0;
 182                         workspace->out_buf.size = min_t(size_t, max_out,
 183                                                         PAGE_SIZE);
 184                 }
 185
 186                 /* We've reached the end of the input */
 187                 if (workspace->in_buf.pos >= len) {
 188                         tot_in += workspace->in_buf.pos;
 189                         break;
 190                 }
 191
 192                 /* Check if we need more input */
 193                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 194                         tot_in += PAGE_SIZE;
 195                         kunmap(in_page);
 196                         put_page(in_page);
 197
 198                         start += PAGE_SIZE;
 199                         len -= PAGE_SIZE;
 200                         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 201                         workspace->in_buf.src = kmap(in_page);
 202                         workspace->in_buf.pos = 0;
 203                         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 204                 }
 205         }
 206         while (1) {
 207                 size_t ret2;
 208
 209                 ret2 = ZSTD_endStream(stream, &workspace->out_buf);
 210                 if (ZSTD_isError(ret2)) {
 211                         pr_debug("BTRFS: ZSTD_endStream returned %d\n",
 212                                         ZSTD_getErrorCode(ret2));
 213                         ret = -EIO;
 214                         goto out;
 215                 }
 216                 if (ret2 == 0) {
 217                         tot_out += workspace->out_buf.pos;
 218                         break;
 219                 }
 220                 if (workspace->out_buf.pos >= max_out) {
 221                         tot_out += workspace->out_buf.pos;
 222                         ret = -E2BIG;
 223                         goto out;
 224                 }
 225
 226                 tot_out += PAGE_SIZE;
 227                 max_out -= PAGE_SIZE;
 228                 kunmap(out_page);
 229                 if (nr_pages == nr_dest_pages) {
 230                         out_page = NULL;
 231                         ret = -E2BIG;
 232                         goto out;
 233                 }
 234                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 235                 if (out_page == NULL) {
 236                         ret = -ENOMEM;
 237                         goto out;
 238                 }
 239                 pages[nr_pages++] = out_page;
 240                 workspace->out_buf.dst = kmap(out_page);
 241                 workspace->out_buf.pos = 0;
 242                 workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 243         }
 244
 245         if (tot_out >= tot_in) {
 246                 ret = -E2BIG;
 247                 goto out;
 248         }
 249
 250         ret = 0;
 251         *total_in = tot_in;
 252         *total_out = tot_out;
 253 out:
 254         *out_pages = nr_pages;
 255         /* Cleanup */
 256         if (in_page) {
 257                 kunmap(in_page);
 258                 put_page(in_page);
 259         }
 260         if (out_page)
 261                 kunmap(out_page);
 262         return ret;
 263 }
 264
 265 static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 266 {
 267         struct workspace *workspace = list_entry(ws, struct workspace, list);
 268         struct page **pages_in = cb->compressed_pages;
 269         u64 disk_start = cb->start;
 270         struct bio *orig_bio = cb->orig_bio;
 271         size_t srclen = cb->compressed_len;
 272         ZSTD_DStream *stream;
 273         int ret = 0;
 274         unsigned long page_in_index = 0;
 275         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 276         unsigned long buf_start;
 277         unsigned long total_out = 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         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 288         workspace->in_buf.pos = 0;
 289         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 290
 291         workspace->out_buf.dst = workspace->buf;
 292         workspace->out_buf.pos = 0;
 293         workspace->out_buf.size = PAGE_SIZE;
 294
 295         while (1) {
 296                 size_t ret2;
 297
 298                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
 299                                 &workspace->in_buf);
 300                 if (ZSTD_isError(ret2)) {
 301                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 302                                         ZSTD_getErrorCode(ret2));
 303                         ret = -EIO;
 304                         goto done;
 305                 }
 306                 buf_start = total_out;
 307                 total_out += workspace->out_buf.pos;
 308                 workspace->out_buf.pos = 0;
 309
 310                 ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
 311                                 buf_start, total_out, disk_start, orig_bio);
 312                 if (ret == 0)
 313                         break;
 314
 315                 if (workspace->in_buf.pos >= srclen)
 316                         break;
 317
 318                 /* Check if we've hit the end of a frame */
 319                 if (ret2 == 0)
 320                         break;
 321
 322                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 323                         kunmap(pages_in[page_in_index++]);
 324                         if (page_in_index >= total_pages_in) {
 325                                 workspace->in_buf.src = NULL;
 326                                 ret = -EIO;
 327                                 goto done;
 328                         }
 329                         srclen -= PAGE_SIZE;
 330                         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 331                         workspace->in_buf.pos = 0;
 332                         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 333                 }
 334         }
 335         ret = 0;
 336         zero_fill_bio(orig_bio);
 337 done:
 338         if (workspace->in_buf.src)
 339                 kunmap(pages_in[page_in_index]);
 340         return ret;
 341 }
 342
 343 static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 344                 struct page *dest_page,
 345                 unsigned long start_byte,
 346                 size_t srclen, size_t destlen)
 347 {
 348         struct workspace *workspace = list_entry(ws, struct workspace, list);
 349         ZSTD_DStream *stream;
 350         int ret = 0;
 351         size_t ret2;
 352         unsigned long total_out = 0;
 353         unsigned long pg_offset = 0;
 354         char *kaddr;
 355
 356         stream = ZSTD_initDStream(
 357                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 358         if (!stream) {
 359                 pr_warn("BTRFS: ZSTD_initDStream failed\n");
 360                 ret = -EIO;
 361                 goto finish;
 362         }
 363
 364         destlen = min_t(size_t, destlen, PAGE_SIZE);
 365
 366         workspace->in_buf.src = data_in;
 367         workspace->in_buf.pos = 0;
 368         workspace->in_buf.size = srclen;
 369
 370         workspace->out_buf.dst = workspace->buf;
 371         workspace->out_buf.pos = 0;
 372         workspace->out_buf.size = PAGE_SIZE;
 373
 374         ret2 = 1;
 375         while (pg_offset < destlen
 376                && workspace->in_buf.pos < workspace->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, &workspace->out_buf,
 388                                 &workspace->in_buf);
 389                 if (ZSTD_isError(ret2)) {
 390                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 391                                         ZSTD_getErrorCode(ret2));
 392                         ret = -EIO;
 393                         goto finish;
 394                 }
 395
 396                 buf_start = total_out;
 397                 total_out += workspace->out_buf.pos;
 398                 workspace->out_buf.pos = 0;
 399
 400                 if (total_out <= start_byte)
 401                         continue;
 402
 403                 if (total_out > start_byte && buf_start < start_byte)
 404                         buf_offset = start_byte - buf_start;
 405                 else
 406                         buf_offset = 0;
 407
 408                 bytes = min_t(unsigned long, destlen - pg_offset,
 409                                 workspace->out_buf.size - buf_offset);
 410
 411                 kaddr = kmap_atomic(dest_page);
 412                 memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
 413                                 bytes);
 414                 kunmap_atomic(kaddr);
 415
 416                 pg_offset += bytes;
 417         }
 418         ret = 0;
 419 finish:
 420         if (pg_offset < destlen) {
 421                 kaddr = kmap_atomic(dest_page);
 422                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 423                 kunmap_atomic(kaddr);
 424         }
 425         return ret;
 426 }
 427
 428 static void zstd_set_level(struct list_head *ws, unsigned int type)
 429 {
 430 }
 431
 432 const struct btrfs_compress_op btrfs_zstd_compress = {
 433         .alloc_workspace = zstd_alloc_workspace,
 434         .free_workspace = zstd_free_workspace,
 435         .compress_pages = zstd_compress_pages,
 436         .decompress_bio = zstd_decompress_bio,
 437         .decompress = zstd_decompress,
 438         .set_level = zstd_set_level,
 439 };