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/bitmap.h>
  10 #include <linux/err.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mm.h>
  14 #include <linux/sched/mm.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/refcount.h>
  17 #include <linux/sched.h>
  18 #include <linux/slab.h>
  19 #include <linux/zstd.h>
  20 #include "compression.h"
  21 #include "ctree.h"
  22
  23 #define ZSTD_BTRFS_MAX_WINDOWLOG 17
  24 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
  25 #define ZSTD_BTRFS_DEFAULT_LEVEL 3
  26 #define ZSTD_BTRFS_MAX_LEVEL 15
  27 /* 307s to avoid pathologically clashing with transaction commit */
  28 #define ZSTD_BTRFS_RECLAIM_JIFFIES (307 * HZ)
  29
  30 static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level,
  31                                                  size_t src_len)
  32 {
  33         ZSTD_parameters params = ZSTD_getParams(level, 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         unsigned int level;
  46         unsigned int req_level;
  47         unsigned long last_used; /* jiffies */
  48         struct list_head list;
  49         struct list_head lru_list;
  50         ZSTD_inBuffer in_buf;
  51         ZSTD_outBuffer out_buf;
  52 };
  53
  54 /*
  55  * Zstd Workspace Management
  56  *
  57  * Zstd workspaces have different memory requirements depending on the level.
  58  * The zstd workspaces are managed by having individual lists for each level
  59  * and a global lru.  Forward progress is maintained by protecting a max level
  60  * workspace.
  61  *
  62  * Getting a workspace is done by using the bitmap to identify the levels that
  63  * have available workspaces and scans up.  This lets us recycle higher level
  64  * workspaces because of the monotonic memory guarantee.  A workspace's
  65  * last_used is only updated if it is being used by the corresponding memory
  66  * level.  Putting a workspace involves adding it back to the appropriate places
  67  * and adding it back to the lru if necessary.
  68  *
  69  * A timer is used to reclaim workspaces if they have not been used for
  70  * ZSTD_BTRFS_RECLAIM_JIFFIES.  This helps keep only active workspaces around.
  71  * The upper bound is provided by the workqueue limit which is 2 (percpu limit).
  72  */
  73
  74 struct zstd_workspace_manager {
  75         const struct btrfs_compress_op *ops;
  76         spinlock_t lock;
  77         struct list_head lru_list;
  78         struct list_head idle_ws[ZSTD_BTRFS_MAX_LEVEL];
  79         unsigned long active_map;
  80         wait_queue_head_t wait;
  81         struct timer_list timer;
  82 };
  83
  84 static struct zstd_workspace_manager wsm;
  85
  86 static size_t zstd_ws_mem_sizes[ZSTD_BTRFS_MAX_LEVEL];
  87
  88 static inline struct workspace *list_to_workspace(struct list_head *list)
  89 {
  90         return container_of(list, struct workspace, list);
  91 }
  92
  93 static void zstd_free_workspace(struct list_head *ws);
  94 static struct list_head *zstd_alloc_workspace(unsigned int level);
  95
  96 /*
  97  * zstd_reclaim_timer_fn - reclaim timer
  98  * @t: timer
  99  *
 100  * This scans the lru_list and attempts to reclaim any workspace that hasn't
 101  * been used for ZSTD_BTRFS_RECLAIM_JIFFIES.
 102  */
 103 static void zstd_reclaim_timer_fn(struct timer_list *timer)
 104 {
 105         unsigned long reclaim_threshold = jiffies - ZSTD_BTRFS_RECLAIM_JIFFIES;
 106         struct list_head *pos, *next;
 107
 108         spin_lock_bh(&wsm.lock);
 109
 110         if (list_empty(&wsm.lru_list)) {
 111                 spin_unlock_bh(&wsm.lock);
 112                 return;
 113         }
 114
 115         list_for_each_prev_safe(pos, next, &wsm.lru_list) {
 116                 struct workspace *victim = container_of(pos, struct workspace,
 117                                                         lru_list);
 118                 unsigned int level;
 119
 120                 if (time_after(victim->last_used, reclaim_threshold))
 121                         break;
 122
 123                 /* workspace is in use */
 124                 if (victim->req_level)
 125                         continue;
 126
 127                 level = victim->level;
 128                 list_del(&victim->lru_list);
 129                 list_del(&victim->list);
 130                 zstd_free_workspace(&victim->list);
 131
 132                 if (list_empty(&wsm.idle_ws[level - 1]))
 133                         clear_bit(level - 1, &wsm.active_map);
 134
 135         }
 136
 137         if (!list_empty(&wsm.lru_list))
 138                 mod_timer(&wsm.timer, jiffies + ZSTD_BTRFS_RECLAIM_JIFFIES);
 139
 140         spin_unlock_bh(&wsm.lock);
 141 }
 142
 143 /*
 144  * zstd_calc_ws_mem_sizes - calculate monotonic memory bounds
 145  *
 146  * It is possible based on the level configurations that a higher level
 147  * workspace uses less memory than a lower level workspace.  In order to reuse
 148  * workspaces, this must be made a monotonic relationship.  This precomputes
 149  * the required memory for each level and enforces the monotonicity between
 150  * level and memory required.
 151  */
 152 static void zstd_calc_ws_mem_sizes(void)
 153 {
 154         size_t max_size = 0;
 155         unsigned int level;
 156
 157         for (level = 1; level <= ZSTD_BTRFS_MAX_LEVEL; level++) {
 158                 ZSTD_parameters params =
 159                         zstd_get_btrfs_parameters(level, ZSTD_BTRFS_MAX_INPUT);
 160                 size_t level_size =
 161                         max_t(size_t,
 162                               ZSTD_CStreamWorkspaceBound(params.cParams),
 163                               ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
 164
 165                 max_size = max_t(size_t, max_size, level_size);
 166                 zstd_ws_mem_sizes[level - 1] = max_size;
 167         }
 168 }
 169
 170 static void zstd_init_workspace_manager(void)
 171 {
 172         struct list_head *ws;
 173         int i;
 174
 175         zstd_calc_ws_mem_sizes();
 176
 177         wsm.ops = &btrfs_zstd_compress;
 178         spin_lock_init(&wsm.lock);
 179         init_waitqueue_head(&wsm.wait);
 180         timer_setup(&wsm.timer, zstd_reclaim_timer_fn, 0);
 181
 182         INIT_LIST_HEAD(&wsm.lru_list);
 183         for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++)
 184                 INIT_LIST_HEAD(&wsm.idle_ws[i]);
 185
 186         ws = zstd_alloc_workspace(ZSTD_BTRFS_MAX_LEVEL);
 187         if (IS_ERR(ws)) {
 188                 pr_warn(
 189                 "BTRFS: cannot preallocate zstd compression workspace\n");
 190         } else {
 191                 set_bit(ZSTD_BTRFS_MAX_LEVEL - 1, &wsm.active_map);
 192                 list_add(ws, &wsm.idle_ws[ZSTD_BTRFS_MAX_LEVEL - 1]);
 193         }
 194 }
 195
 196 static void zstd_cleanup_workspace_manager(void)
 197 {
 198         struct workspace *workspace;
 199         int i;
 200
 201         spin_lock_bh(&wsm.lock);
 202         for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) {
 203                 while (!list_empty(&wsm.idle_ws[i])) {
 204                         workspace = container_of(wsm.idle_ws[i].next,
 205                                                  struct workspace, list);
 206                         list_del(&workspace->list);
 207                         list_del(&workspace->lru_list);
 208                         zstd_free_workspace(&workspace->list);
 209                 }
 210         }
 211         spin_unlock_bh(&wsm.lock);
 212
 213         del_timer_sync(&wsm.timer);
 214 }
 215
 216 /*
 217  * zstd_find_workspace - find workspace
 218  * @level: compression level
 219  *
 220  * This iterates over the set bits in the active_map beginning at the requested
 221  * compression level.  This lets us utilize already allocated workspaces before
 222  * allocating a new one.  If the workspace is of a larger size, it is used, but
 223  * the place in the lru_list and last_used times are not updated.  This is to
 224  * offer the opportunity to reclaim the workspace in favor of allocating an
 225  * appropriately sized one in the future.
 226  */
 227 static struct list_head *zstd_find_workspace(unsigned int level)
 228 {
 229         struct list_head *ws;
 230         struct workspace *workspace;
 231         int i = level - 1;
 232
 233         spin_lock_bh(&wsm.lock);
 234         for_each_set_bit_from(i, &wsm.active_map, ZSTD_BTRFS_MAX_LEVEL) {
 235                 if (!list_empty(&wsm.idle_ws[i])) {
 236                         ws = wsm.idle_ws[i].next;
 237                         workspace = list_to_workspace(ws);
 238                         list_del_init(ws);
 239                         /* keep its place if it's a lower level using this */
 240                         workspace->req_level = level;
 241                         if (level == workspace->level)
 242                                 list_del(&workspace->lru_list);
 243                         if (list_empty(&wsm.idle_ws[i]))
 244                                 clear_bit(i, &wsm.active_map);
 245                         spin_unlock_bh(&wsm.lock);
 246                         return ws;
 247                 }
 248         }
 249         spin_unlock_bh(&wsm.lock);
 250
 251         return NULL;
 252 }
 253
 254 /*
 255  * zstd_get_workspace - zstd's get_workspace
 256  * @level: compression level
 257  *
 258  * If @level is 0, then any compression level can be used.  Therefore, we begin
 259  * scanning from 1.  We first scan through possible workspaces and then after
 260  * attempt to allocate a new workspace.  If we fail to allocate one due to
 261  * memory pressure, go to sleep waiting for the max level workspace to free up.
 262  */
 263 static struct list_head *zstd_get_workspace(unsigned int level)
 264 {
 265         struct list_head *ws;
 266         unsigned int nofs_flag;
 267
 268         /* level == 0 means we can use any workspace */
 269         if (!level)
 270                 level = 1;
 271
 272 again:
 273         ws = zstd_find_workspace(level);
 274         if (ws)
 275                 return ws;
 276
 277         nofs_flag = memalloc_nofs_save();
 278         ws = zstd_alloc_workspace(level);
 279         memalloc_nofs_restore(nofs_flag);
 280
 281         if (IS_ERR(ws)) {
 282                 DEFINE_WAIT(wait);
 283
 284                 prepare_to_wait(&wsm.wait, &wait, TASK_UNINTERRUPTIBLE);
 285                 schedule();
 286                 finish_wait(&wsm.wait, &wait);
 287
 288                 goto again;
 289         }
 290
 291         return ws;
 292 }
 293
 294 /*
 295  * zstd_put_workspace - zstd put_workspace
 296  * @ws: list_head for the workspace
 297  *
 298  * When putting back a workspace, we only need to update the LRU if we are of
 299  * the requested compression level.  Here is where we continue to protect the
 300  * max level workspace or update last_used accordingly.  If the reclaim timer
 301  * isn't set, it is also set here.  Only the max level workspace tries and wakes
 302  * up waiting workspaces.
 303  */
 304 static void zstd_put_workspace(struct list_head *ws)
 305 {
 306         struct workspace *workspace = list_to_workspace(ws);
 307
 308         spin_lock_bh(&wsm.lock);
 309
 310         /* A node is only taken off the lru if we are the corresponding level */
 311         if (workspace->req_level == workspace->level) {
 312                 /* Hide a max level workspace from reclaim */
 313                 if (list_empty(&wsm.idle_ws[ZSTD_BTRFS_MAX_LEVEL - 1])) {
 314                         INIT_LIST_HEAD(&workspace->lru_list);
 315                 } else {
 316                         workspace->last_used = jiffies;
 317                         list_add(&workspace->lru_list, &wsm.lru_list);
 318                         if (!timer_pending(&wsm.timer))
 319                                 mod_timer(&wsm.timer,
 320                                           jiffies + ZSTD_BTRFS_RECLAIM_JIFFIES);
 321                 }
 322         }
 323
 324         set_bit(workspace->level - 1, &wsm.active_map);
 325         list_add(&workspace->list, &wsm.idle_ws[workspace->level - 1]);
 326         workspace->req_level = 0;
 327
 328         spin_unlock_bh(&wsm.lock);
 329
 330         if (workspace->level == ZSTD_BTRFS_MAX_LEVEL)
 331                 cond_wake_up(&wsm.wait);
 332 }
 333
 334 static void zstd_free_workspace(struct list_head *ws)
 335 {
 336         struct workspace *workspace = list_entry(ws, struct workspace, list);
 337
 338         kvfree(workspace->mem);
 339         kfree(workspace->buf);
 340         kfree(workspace);
 341 }
 342
 343 static struct list_head *zstd_alloc_workspace(unsigned int level)
 344 {
 345         struct workspace *workspace;
 346
 347         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
 348         if (!workspace)
 349                 return ERR_PTR(-ENOMEM);
 350
 351         workspace->size = zstd_ws_mem_sizes[level - 1];
 352         workspace->level = level;
 353         workspace->req_level = level;
 354         workspace->last_used = jiffies;
 355         workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
 356         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 357         if (!workspace->mem || !workspace->buf)
 358                 goto fail;
 359
 360         INIT_LIST_HEAD(&workspace->list);
 361         INIT_LIST_HEAD(&workspace->lru_list);
 362
 363         return &workspace->list;
 364 fail:
 365         zstd_free_workspace(&workspace->list);
 366         return ERR_PTR(-ENOMEM);
 367 }
 368
 369 static int zstd_compress_pages(struct list_head *ws,
 370                 struct address_space *mapping,
 371                 u64 start,
 372                 struct page **pages,
 373                 unsigned long *out_pages,
 374                 unsigned long *total_in,
 375                 unsigned long *total_out)
 376 {
 377         struct workspace *workspace = list_entry(ws, struct workspace, list);
 378         ZSTD_CStream *stream;
 379         int ret = 0;
 380         int nr_pages = 0;
 381         struct page *in_page = NULL;  /* The current page to read */
 382         struct page *out_page = NULL; /* The current page to write to */
 383         unsigned long tot_in = 0;
 384         unsigned long tot_out = 0;
 385         unsigned long len = *total_out;
 386         const unsigned long nr_dest_pages = *out_pages;
 387         unsigned long max_out = nr_dest_pages * PAGE_SIZE;
 388         ZSTD_parameters params = zstd_get_btrfs_parameters(workspace->req_level,
 389                                                            len);
 390
 391         *out_pages = 0;
 392         *total_out = 0;
 393         *total_in = 0;
 394
 395         /* Initialize the stream */
 396         stream = ZSTD_initCStream(params, len, workspace->mem,
 397                         workspace->size);
 398         if (!stream) {
 399                 pr_warn("BTRFS: ZSTD_initCStream failed\n");
 400                 ret = -EIO;
 401                 goto out;
 402         }
 403
 404         /* map in the first page of input data */
 405         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 406         workspace->in_buf.src = kmap(in_page);
 407         workspace->in_buf.pos = 0;
 408         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 409
 410
 411         /* Allocate and map in the output buffer */
 412         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 413         if (out_page == NULL) {
 414                 ret = -ENOMEM;
 415                 goto out;
 416         }
 417         pages[nr_pages++] = out_page;
 418         workspace->out_buf.dst = kmap(out_page);
 419         workspace->out_buf.pos = 0;
 420         workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 421
 422         while (1) {
 423                 size_t ret2;
 424
 425                 ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
 426                                 &workspace->in_buf);
 427                 if (ZSTD_isError(ret2)) {
 428                         pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
 429                                         ZSTD_getErrorCode(ret2));
 430                         ret = -EIO;
 431                         goto out;
 432                 }
 433
 434                 /* Check to see if we are making it bigger */
 435                 if (tot_in + workspace->in_buf.pos > 8192 &&
 436                                 tot_in + workspace->in_buf.pos <
 437                                 tot_out + workspace->out_buf.pos) {
 438                         ret = -E2BIG;
 439                         goto out;
 440                 }
 441
 442                 /* We've reached the end of our output range */
 443                 if (workspace->out_buf.pos >= max_out) {
 444                         tot_out += workspace->out_buf.pos;
 445                         ret = -E2BIG;
 446                         goto out;
 447                 }
 448
 449                 /* Check if we need more output space */
 450                 if (workspace->out_buf.pos == workspace->out_buf.size) {
 451                         tot_out += PAGE_SIZE;
 452                         max_out -= PAGE_SIZE;
 453                         kunmap(out_page);
 454                         if (nr_pages == nr_dest_pages) {
 455                                 out_page = NULL;
 456                                 ret = -E2BIG;
 457                                 goto out;
 458                         }
 459                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 460                         if (out_page == NULL) {
 461                                 ret = -ENOMEM;
 462                                 goto out;
 463                         }
 464                         pages[nr_pages++] = out_page;
 465                         workspace->out_buf.dst = kmap(out_page);
 466                         workspace->out_buf.pos = 0;
 467                         workspace->out_buf.size = min_t(size_t, max_out,
 468                                                         PAGE_SIZE);
 469                 }
 470
 471                 /* We've reached the end of the input */
 472                 if (workspace->in_buf.pos >= len) {
 473                         tot_in += workspace->in_buf.pos;
 474                         break;
 475                 }
 476
 477                 /* Check if we need more input */
 478                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 479                         tot_in += PAGE_SIZE;
 480                         kunmap(in_page);
 481                         put_page(in_page);
 482
 483                         start += PAGE_SIZE;
 484                         len -= PAGE_SIZE;
 485                         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
 486                         workspace->in_buf.src = kmap(in_page);
 487                         workspace->in_buf.pos = 0;
 488                         workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 489                 }
 490         }
 491         while (1) {
 492                 size_t ret2;
 493
 494                 ret2 = ZSTD_endStream(stream, &workspace->out_buf);
 495                 if (ZSTD_isError(ret2)) {
 496                         pr_debug("BTRFS: ZSTD_endStream returned %d\n",
 497                                         ZSTD_getErrorCode(ret2));
 498                         ret = -EIO;
 499                         goto out;
 500                 }
 501                 if (ret2 == 0) {
 502                         tot_out += workspace->out_buf.pos;
 503                         break;
 504                 }
 505                 if (workspace->out_buf.pos >= max_out) {
 506                         tot_out += workspace->out_buf.pos;
 507                         ret = -E2BIG;
 508                         goto out;
 509                 }
 510
 511                 tot_out += PAGE_SIZE;
 512                 max_out -= PAGE_SIZE;
 513                 kunmap(out_page);
 514                 if (nr_pages == nr_dest_pages) {
 515                         out_page = NULL;
 516                         ret = -E2BIG;
 517                         goto out;
 518                 }
 519                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
 520                 if (out_page == NULL) {
 521                         ret = -ENOMEM;
 522                         goto out;
 523                 }
 524                 pages[nr_pages++] = out_page;
 525                 workspace->out_buf.dst = kmap(out_page);
 526                 workspace->out_buf.pos = 0;
 527                 workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 528         }
 529
 530         if (tot_out >= tot_in) {
 531                 ret = -E2BIG;
 532                 goto out;
 533         }
 534
 535         ret = 0;
 536         *total_in = tot_in;
 537         *total_out = tot_out;
 538 out:
 539         *out_pages = nr_pages;
 540         /* Cleanup */
 541         if (in_page) {
 542                 kunmap(in_page);
 543                 put_page(in_page);
 544         }
 545         if (out_page)
 546                 kunmap(out_page);
 547         return ret;
 548 }
 549
 550 static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 551 {
 552         struct workspace *workspace = list_entry(ws, struct workspace, list);
 553         struct page **pages_in = cb->compressed_pages;
 554         u64 disk_start = cb->start;
 555         struct bio *orig_bio = cb->orig_bio;
 556         size_t srclen = cb->compressed_len;
 557         ZSTD_DStream *stream;
 558         int ret = 0;
 559         unsigned long page_in_index = 0;
 560         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 561         unsigned long buf_start;
 562         unsigned long total_out = 0;
 563
 564         stream = ZSTD_initDStream(
 565                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 566         if (!stream) {
 567                 pr_debug("BTRFS: ZSTD_initDStream failed\n");
 568                 ret = -EIO;
 569                 goto done;
 570         }
 571
 572         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 573         workspace->in_buf.pos = 0;
 574         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 575
 576         workspace->out_buf.dst = workspace->buf;
 577         workspace->out_buf.pos = 0;
 578         workspace->out_buf.size = PAGE_SIZE;
 579
 580         while (1) {
 581                 size_t ret2;
 582
 583                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
 584                                 &workspace->in_buf);
 585                 if (ZSTD_isError(ret2)) {
 586                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 587                                         ZSTD_getErrorCode(ret2));
 588                         ret = -EIO;
 589                         goto done;
 590                 }
 591                 buf_start = total_out;
 592                 total_out += workspace->out_buf.pos;
 593                 workspace->out_buf.pos = 0;
 594
 595                 ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
 596                                 buf_start, total_out, disk_start, orig_bio);
 597                 if (ret == 0)
 598                         break;
 599
 600                 if (workspace->in_buf.pos >= srclen)
 601                         break;
 602
 603                 /* Check if we've hit the end of a frame */
 604                 if (ret2 == 0)
 605                         break;
 606
 607                 if (workspace->in_buf.pos == workspace->in_buf.size) {
 608                         kunmap(pages_in[page_in_index++]);
 609                         if (page_in_index >= total_pages_in) {
 610                                 workspace->in_buf.src = NULL;
 611                                 ret = -EIO;
 612                                 goto done;
 613                         }
 614                         srclen -= PAGE_SIZE;
 615                         workspace->in_buf.src = kmap(pages_in[page_in_index]);
 616                         workspace->in_buf.pos = 0;
 617                         workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 618                 }
 619         }
 620         ret = 0;
 621         zero_fill_bio(orig_bio);
 622 done:
 623         if (workspace->in_buf.src)
 624                 kunmap(pages_in[page_in_index]);
 625         return ret;
 626 }
 627
 628 static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 629                 struct page *dest_page,
 630                 unsigned long start_byte,
 631                 size_t srclen, size_t destlen)
 632 {
 633         struct workspace *workspace = list_entry(ws, struct workspace, list);
 634         ZSTD_DStream *stream;
 635         int ret = 0;
 636         size_t ret2;
 637         unsigned long total_out = 0;
 638         unsigned long pg_offset = 0;
 639         char *kaddr;
 640
 641         stream = ZSTD_initDStream(
 642                         ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
 643         if (!stream) {
 644                 pr_warn("BTRFS: ZSTD_initDStream failed\n");
 645                 ret = -EIO;
 646                 goto finish;
 647         }
 648
 649         destlen = min_t(size_t, destlen, PAGE_SIZE);
 650
 651         workspace->in_buf.src = data_in;
 652         workspace->in_buf.pos = 0;
 653         workspace->in_buf.size = srclen;
 654
 655         workspace->out_buf.dst = workspace->buf;
 656         workspace->out_buf.pos = 0;
 657         workspace->out_buf.size = PAGE_SIZE;
 658
 659         ret2 = 1;
 660         while (pg_offset < destlen
 661                && workspace->in_buf.pos < workspace->in_buf.size) {
 662                 unsigned long buf_start;
 663                 unsigned long buf_offset;
 664                 unsigned long bytes;
 665
 666                 /* Check if the frame is over and we still need more input */
 667                 if (ret2 == 0) {
 668                         pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
 669                         ret = -EIO;
 670                         goto finish;
 671                 }
 672                 ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
 673                                 &workspace->in_buf);
 674                 if (ZSTD_isError(ret2)) {
 675                         pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 676                                         ZSTD_getErrorCode(ret2));
 677                         ret = -EIO;
 678                         goto finish;
 679                 }
 680
 681                 buf_start = total_out;
 682                 total_out += workspace->out_buf.pos;
 683                 workspace->out_buf.pos = 0;
 684
 685                 if (total_out <= start_byte)
 686                         continue;
 687
 688                 if (total_out > start_byte && buf_start < start_byte)
 689                         buf_offset = start_byte - buf_start;
 690                 else
 691                         buf_offset = 0;
 692
 693                 bytes = min_t(unsigned long, destlen - pg_offset,
 694                                 workspace->out_buf.size - buf_offset);
 695
 696                 kaddr = kmap_atomic(dest_page);
 697                 memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
 698                                 bytes);
 699                 kunmap_atomic(kaddr);
 700
 701                 pg_offset += bytes;
 702         }
 703         ret = 0;
 704 finish:
 705         if (pg_offset < destlen) {
 706                 kaddr = kmap_atomic(dest_page);
 707                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
 708                 kunmap_atomic(kaddr);
 709         }
 710         return ret;
 711 }
 712
 713 static unsigned int zstd_set_level(unsigned int level)
 714 {
 715         if (!level)
 716                 return ZSTD_BTRFS_DEFAULT_LEVEL;
 717
 718         return min_t(unsigned int, level, ZSTD_BTRFS_MAX_LEVEL);
 719 }
 720
 721 const struct btrfs_compress_op btrfs_zstd_compress = {
 722         .init_workspace_manager = zstd_init_workspace_manager,
 723         .cleanup_workspace_manager = zstd_cleanup_workspace_manager,
 724         .get_workspace = zstd_get_workspace,
 725         .put_workspace = zstd_put_workspace,
 726         .alloc_workspace = zstd_alloc_workspace,
 727         .free_workspace = zstd_free_workspace,
 728         .compress_pages = zstd_compress_pages,
 729         .decompress_bio = zstd_decompress_bio,
 730         .decompress = zstd_decompress,
 731         .set_level = zstd_set_level,
 732 };