fs/btrfs/zstd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2016-present, Facebook, Inc.
   4  * All rights reserved.
   5  *
   6  */
   7
   8 #include <linux/bio.h>
   9 #include <linux/err.h>
  10 #include <linux/init.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/refcount.h>
  15 #include <linux/sched.h>
  16 #include <linux/slab.h>
  17 #include <linux/zstd.h>
  18 #include "compression.h"
  19
  20 #define ZSTD_BTRFS_MAX_WINDOWLOG 17
  21 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
  22 #define ZSTD_BTRFS_DEFAULT_LEVEL 3
  23
  24 static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level,
  25                                                  size_t src_len)
  26 {
  27         ZSTD_parameters params = ZSTD_getParams(level, src_len, 0);
  28
  29         if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
  30                 params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
  31         WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
  32         return params;
  33 }
  34
  35 struct workspace {
  36         void *mem;
  37         size_t size;
  38         char *buf;
  39         unsigned int req_level;
  40         struct list_head list;
  41         ZSTD_inBuffer in_buf;
  42         ZSTD_outBuffer out_buf;
  43 };
  44
  45 static struct workspace_manager wsm;
  46
  47 static void zstd_init_workspace_manager(void)
  48 {
  49         btrfs_init_workspace_manager(&wsm, &btrfs_zstd_compress);
  50 }
  51
  52 static void zstd_cleanup_workspace_manager(void)
  53 {
  54         btrfs_cleanup_workspace_manager(&wsm);
  55 }
  56
  57 static struct list_head *zstd_get_workspace(unsigned int level)
  58 {
  59         struct list_head *ws = btrfs_get_workspace(&wsm, level);
  60         struct workspace *workspace = list_entry(ws, struct workspace, list);
  61
  62         workspace->req_level = level;
  63
  64         return ws;
  65 }
  66
  67 static void zstd_put_workspace(struct list_head *ws)
  68 {
  69         btrfs_put_workspace(&wsm, ws);
  70 }
  71
  72 static void zstd_free_workspace(struct list_head *ws)
  73 {
  74         struct workspace *workspace = list_entry(ws, struct workspace, list);
  75
  76         kvfree(workspace->mem);
  77         kfree(workspace->buf);
  78         kfree(workspace);
  79 }
  80
  81 static struct list_head *zstd_alloc_workspace(unsigned int level)
  82 {
  83         ZSTD_parameters params =
  84                         zstd_get_btrfs_parameters(level, ZSTD_BTRFS_MAX_INPUT);
  85         struct workspace *workspace;
  86
  87         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
  88         if (!workspace)
  89                 return ERR_PTR(-ENOMEM);
  90
  91         workspace->size = max_t(size_t,
  92                         ZSTD_CStreamWorkspaceBound(params.cParams),
  93                         ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
  94         workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
  95         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  96         if (!workspace->mem || !workspace->buf)
  97                 goto fail;
  98
  99         INIT_LIST_HEAD(&workspace->list);
 100
 101         return &workspace->list;
 102 fail:
 103         zstd_free_workspace(&workspace->list);
 104         return ERR_PTR(-ENOMEM);
 105 }
 106
 107 static int zstd_compress_pages(struct list_head *ws,
 108                 struct address_space *mapping,
 109                 u64 start,
 110                 struct page **pages,
 111                 unsigned long *out_pages,
 112                 unsigned long *total_in,
 113                 unsigned long *total_out)
 114 {
 115         struct workspace *workspace = list_entry(ws, struct workspace, list);
 116         ZSTD_CStream *stream;
 117         int ret = 0;
 118         int nr_pages = 0;
 119         struct page *in_page = NULL;  /* The current page to read */
 120         struct page *out_page = NULL; /* The current page to write to */
 121         unsigned long tot_in = 0;
 122         unsigned long tot_out = 0;
 123         unsigned long len = *total_out;
 124         const unsigned long nr_dest_pages = *out_pages;
 125         unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 126         ZSTD_parameters params = zstd_get_btrfs_parameters(workspace->req_level,
 127                                                            len);
 128
 129         *out_pages = 0;
 130         *total_out = 0;
 131         *total_in = 0;
 132
 133         /* Initialize the stream */
 134         stream = ZSTD_initCStream(params, len, workspace->mem,
 135                         workspace->size);
 136         if (!stream) {
 137                 pr_warn("BTRFS: ZSTD_initCStream failed\n");
 138                 ret = -EIO;
 139                 goto out;
 140         }
 141
 142         /* map in the first page of input data */
 143         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 144         workspace->in_buf.src = kmap(in_page);
 145         workspace->in_buf.pos = 0;
 146         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 147
 148
 149         /* Allocate and map in the output buffer */
 150         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 151         if (out_page == NULL) {
 152                 ret = -ENOMEM;
 153                 goto out;
 154         }
 155         pages[nr_pages++] = out_page;
 156         workspace->out_buf.dst = kmap(out_page);
 157         workspace->out_buf.pos = 0;
 158         workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 159
 160         while (1) {
 161                 size_t ret2;
 162
 163                 ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
 164                                 &workspace->in_buf);
 165                 if (ZSTD_isError(ret2)) {
 166                         pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
 167                                         ZSTD_getErrorCode(ret2));
 168                         ret = -EIO;
 169                         goto out;
 170                 }
 171
 172                 /* Check to see if we are making it bigger */
 173                 if (tot_in + workspace->in_buf.pos > 8192 &&
 174                                 tot_in + workspace->in_buf.pos <
 175                                 tot_out + workspace->out_buf.pos) {
 176                         ret = -E2BIG;
 177                         goto out;
 178                 }
 179
 180                 /* We've reached the end of our output range */
 181                 if (workspace->out_buf.pos >= max_out) {
 182                         tot_out += workspace->out_buf.pos;
 183                         ret = -E2BIG;
 184                         goto out;
 185                 }
 186
 187                 /* Check if we need more output space */
 188                 if (workspace->out_buf.pos == workspace->out_buf.size) {
 189                         tot_out += PAGE_SIZE;
 190                         max_out -= PAGE_SIZE;
 191                         kunmap(out_page);
 192                         if (nr_pages == nr_dest_pages) {
 193                                 out_page = NULL;
 194                                 ret = -E2BIG;
 195                                 goto out;
 196                         }
 197                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 198                         if (out_page == NULL) {
 199                                 ret = -ENOMEM;
 200                                 goto out;
 201                         }
 202                         pages[nr_pages++] = out_page;
 203                         workspace->out_buf.dst = kmap(out_page);
 204                         workspace->out_buf.pos = 0;
 205                         workspace->out_buf.size = min_t(size_t, max_out,
 206                                                         PAGE_SIZE);
 207                 }
 208
 209                 /* We've reached the end of the input */
 210                 if (workspace->in_buf.pos >= len) {
 211                         tot_in += workspace->in_buf.pos;
 212                         break;
 213                 }
 214
 215                 /* Check if we need more input */
 216                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 217                         tot_in += PAGE_SIZE;
 218                         kunmap(in_page);
 219                         put_page(in_page);
 220
 221                         start += PAGE_SIZE;
 222                         len -= PAGE_SIZE;
 223                         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 224                         workspace->in_buf.src = kmap(in_page);
 225                         workspace->in_buf.pos = 0;
 226                         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 227                 }
 228         }
 229         while (1) {
 230                 size_t ret2;
 231
 232                 ret2 = ZSTD_endStream(stream, &workspace->out_buf);
 233                 if (ZSTD_isError(ret2)) {
 234                         pr_debug("BTRFS: ZSTD_endStream returned %d\n",
 235                                         ZSTD_getErrorCode(ret2));
 236                         ret = -EIO;
 237                         goto out;
 238                 }
 239                 if (ret2 == 0) {
 240                         tot_out += workspace->out_buf.pos;
 241                         break;
 242                 }
 243                 if (workspace->out_buf.pos >= max_out) {
 244                         tot_out += workspace->out_buf.pos;
 245                         ret = -E2BIG;
 246                         goto out;
 247                 }
 248
 249                 tot_out += PAGE_SIZE;
 250                 max_out -= PAGE_SIZE;
 251                 kunmap(out_page);
 252                 if (nr_pages == nr_dest_pages) {
 253                         out_page = NULL;
 254                         ret = -E2BIG;
 255                         goto out;
 256                 }
 257                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 258                 if (out_page == NULL) {
 259                         ret = -ENOMEM;
 260                         goto out;
 261                 }
 262                 pages[nr_pages++] = out_page;
 263                 workspace->out_buf.dst = kmap(out_page);
 264                 workspace->out_buf.pos = 0;
 265                 workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 266         }
 267
 268         if (tot_out >= tot_in) {
 269                 ret = -E2BIG;
 270                 goto out;
 271         }
 272
 273         ret = 0;
 274         *total_in = tot_in;
 275         *total_out = tot_out;
 276 out:
 277         *out_pages = nr_pages;
 278         /* Cleanup */
 279         if (in_page) {
 280                 kunmap(in_page);
 281                 put_page(in_page);
 282         }
 283         if (out_page)
 284                 kunmap(out_page);
 285         return ret;
 286 }
 287
 288 static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 289 {
 290         struct workspace *workspace = list_entry(ws, struct workspace, list);
 291         struct page **pages_in = cb->compressed_pages;
 292         u64 disk_start = cb->start;
 293         struct bio *orig_bio = cb->orig_bio;
 294         size_t srclen = cb->compressed_len;
 295         ZSTD_DStream *stream;
 296         int ret = 0;
 297         unsigned long page_in_index = 0;
 298         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 299         unsigned long buf_start;
 300         unsigned long total_out = 0;
 301
 302         stream = ZSTD_initDStream(
 303                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 304         if (!stream) {
 305                 pr_debug("BTRFS: ZSTD_initDStream failed\n");
 306                 ret = -EIO;
 307                 goto done;
 308         }
 309
 310         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 311         workspace->in_buf.pos = 0;
 312         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 313
 314         workspace->out_buf.dst = workspace->buf;
 315         workspace->out_buf.pos = 0;
 316         workspace->out_buf.size = PAGE_SIZE;
 317
 318         while (1) {
 319                 size_t ret2;
 320
 321                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
 322                                 &workspace->in_buf);
 323                 if (ZSTD_isError(ret2)) {
 324                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 325                                         ZSTD_getErrorCode(ret2));
 326                         ret = -EIO;
 327                         goto done;
 328                 }
 329                 buf_start = total_out;
 330                 total_out += workspace->out_buf.pos;
 331                 workspace->out_buf.pos = 0;
 332
 333                 ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
 334                                 buf_start, total_out, disk_start, orig_bio);
 335                 if (ret == 0)
 336                         break;
 337
 338                 if (workspace->in_buf.pos >= srclen)
 339                         break;
 340
 341                 /* Check if we've hit the end of a frame */
 342                 if (ret2 == 0)
 343                         break;
 344
 345                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 346                         kunmap(pages_in[page_in_index++]);
 347                         if (page_in_index >= total_pages_in) {
 348                                 workspace->in_buf.src = NULL;
 349                                 ret = -EIO;
 350                                 goto done;
 351                         }
 352                         srclen -= PAGE_SIZE;
 353                         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 354                         workspace->in_buf.pos = 0;
 355                         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 356                 }
 357         }
 358         ret = 0;
 359         zero_fill_bio(orig_bio);
 360 done:
 361         if (workspace->in_buf.src)
 362                 kunmap(pages_in[page_in_index]);
 363         return ret;
 364 }
 365
 366 static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 367                 struct page *dest_page,
 368                 unsigned long start_byte,
 369                 size_t srclen, size_t destlen)
 370 {
 371         struct workspace *workspace = list_entry(ws, struct workspace, list);
 372         ZSTD_DStream *stream;
 373         int ret = 0;
 374         size_t ret2;
 375         unsigned long total_out = 0;
 376         unsigned long pg_offset = 0;
 377         char *kaddr;
 378
 379         stream = ZSTD_initDStream(
 380                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 381         if (!stream) {
 382                 pr_warn("BTRFS: ZSTD_initDStream failed\n");
 383                 ret = -EIO;
 384                 goto finish;
 385         }
 386
 387         destlen = min_t(size_t, destlen, PAGE_SIZE);
 388
 389         workspace->in_buf.src = data_in;
 390         workspace->in_buf.pos = 0;
 391         workspace->in_buf.size = srclen;
 392
 393         workspace->out_buf.dst = workspace->buf;
 394         workspace->out_buf.pos = 0;
 395         workspace->out_buf.size = PAGE_SIZE;
 396
 397         ret2 = 1;
 398         while (pg_offset < destlen
 399                && workspace->in_buf.pos < workspace->in_buf.size) {
 400                 unsigned long buf_start;
 401                 unsigned long buf_offset;
 402                 unsigned long bytes;
 403
 404                 /* Check if the frame is over and we still need more input */
 405                 if (ret2 == 0) {
 406                         pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
 407                         ret = -EIO;
 408                         goto finish;
 409                 }
 410                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
 411                                 &workspace->in_buf);
 412                 if (ZSTD_isError(ret2)) {
 413                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 414                                         ZSTD_getErrorCode(ret2));
 415                         ret = -EIO;
 416                         goto finish;
 417                 }
 418
 419                 buf_start = total_out;
 420                 total_out += workspace->out_buf.pos;
 421                 workspace->out_buf.pos = 0;
 422
 423                 if (total_out <= start_byte)
 424                         continue;
 425
 426                 if (total_out > start_byte && buf_start < start_byte)
 427                         buf_offset = start_byte - buf_start;
 428                 else
 429                         buf_offset = 0;
 430
 431                 bytes = min_t(unsigned long, destlen - pg_offset,
 432                                 workspace->out_buf.size - buf_offset);
 433
 434                 kaddr = kmap_atomic(dest_page);
 435                 memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
 436                                 bytes);
 437                 kunmap_atomic(kaddr);
 438
 439                 pg_offset += bytes;
 440         }
 441         ret = 0;
 442 finish:
 443         if (pg_offset < destlen) {
 444                 kaddr = kmap_atomic(dest_page);
 445                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 446                 kunmap_atomic(kaddr);
 447         }
 448         return ret;
 449 }
 450
 451 static unsigned int zstd_set_level(unsigned int level)
 452 {
 453         return ZSTD_BTRFS_DEFAULT_LEVEL;
 454 }
 455
 456 const struct btrfs_compress_op btrfs_zstd_compress = {
 457         .init_workspace_manager = zstd_init_workspace_manager,
 458         .cleanup_workspace_manager = zstd_cleanup_workspace_manager,
 459         .get_workspace = zstd_get_workspace,
 460         .put_workspace = zstd_put_workspace,
 461         .alloc_workspace = zstd_alloc_workspace,
 462         .free_workspace = zstd_free_workspace,
 463         .compress_pages = zstd_compress_pages,
 464         .decompress_bio = zstd_decompress_bio,
 465         .decompress = zstd_decompress,
 466         .set_level = zstd_set_level,
 467 };