fs/btrfs/tests/free-space-tests.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013 Fusion IO.  All rights reserved.
   4  */
   5
   6 #include <linux/slab.h>
   7 #include "btrfs-tests.h"
   8 #include "../ctree.h"
   9 #include "../disk-io.h"
  10 #include "../free-space-cache.h"
  11 #include "../block-group.h"
  12
  13 #define BITS_PER_BITMAP         (PAGE_SIZE * 8UL)
  14
  15 /*
  16  * This test just does basic sanity checking, making sure we can add an extent
  17  * entry and remove space from either end and the middle, and make sure we can
  18  * remove space that covers adjacent extent entries.
  19  */
  20 static int test_extents(struct btrfs_block_group *cache)
  21 {
  22         int ret = 0;
  23
  24         test_msg("running extent only tests");
  25
  26         /* First just make sure we can remove an entire entry */
  27         ret = btrfs_add_free_space(cache, 0, SZ_4M);
  28         if (ret) {
  29                 test_err("error adding initial extents %d", ret);
  30                 return ret;
  31         }
  32
  33         ret = btrfs_remove_free_space(cache, 0, SZ_4M);
  34         if (ret) {
  35                 test_err("error removing extent %d", ret);
  36                 return ret;
  37         }
  38
  39         if (test_check_exists(cache, 0, SZ_4M)) {
  40                 test_err("full remove left some lingering space");
  41                 return -1;
  42         }
  43
  44         /* Ok edge and middle cases now */
  45         ret = btrfs_add_free_space(cache, 0, SZ_4M);
  46         if (ret) {
  47                 test_err("error adding half extent %d", ret);
  48                 return ret;
  49         }
  50
  51         ret = btrfs_remove_free_space(cache, 3 * SZ_1M, SZ_1M);
  52         if (ret) {
  53                 test_err("error removing tail end %d", ret);
  54                 return ret;
  55         }
  56
  57         ret = btrfs_remove_free_space(cache, 0, SZ_1M);
  58         if (ret) {
  59                 test_err("error removing front end %d", ret);
  60                 return ret;
  61         }
  62
  63         ret = btrfs_remove_free_space(cache, SZ_2M, 4096);
  64         if (ret) {
  65                 test_err("error removing middle piece %d", ret);
  66                 return ret;
  67         }
  68
  69         if (test_check_exists(cache, 0, SZ_1M)) {
  70                 test_err("still have space at the front");
  71                 return -1;
  72         }
  73
  74         if (test_check_exists(cache, SZ_2M, 4096)) {
  75                 test_err("still have space in the middle");
  76                 return -1;
  77         }
  78
  79         if (test_check_exists(cache, 3 * SZ_1M, SZ_1M)) {
  80                 test_err("still have space at the end");
  81                 return -1;
  82         }
  83
  84         /* Cleanup */
  85         __btrfs_remove_free_space_cache(cache->free_space_ctl);
  86
  87         return 0;
  88 }
  89
  90 static int test_bitmaps(struct btrfs_block_group *cache, u32 sectorsize)
  91 {
  92         u64 next_bitmap_offset;
  93         int ret;
  94
  95         test_msg("running bitmap only tests");
  96
  97         ret = test_add_free_space_entry(cache, 0, SZ_4M, 1);
  98         if (ret) {
  99                 test_err("couldn't create a bitmap entry %d", ret);
 100                 return ret;
 101         }
 102
 103         ret = btrfs_remove_free_space(cache, 0, SZ_4M);
 104         if (ret) {
 105                 test_err("error removing bitmap full range %d", ret);
 106                 return ret;
 107         }
 108
 109         if (test_check_exists(cache, 0, SZ_4M)) {
 110                 test_err("left some space in bitmap");
 111                 return -1;
 112         }
 113
 114         ret = test_add_free_space_entry(cache, 0, SZ_4M, 1);
 115         if (ret) {
 116                 test_err("couldn't add to our bitmap entry %d", ret);
 117                 return ret;
 118         }
 119
 120         ret = btrfs_remove_free_space(cache, SZ_1M, SZ_2M);
 121         if (ret) {
 122                 test_err("couldn't remove middle chunk %d", ret);
 123                 return ret;
 124         }
 125
 126         /*
 127          * The first bitmap we have starts at offset 0 so the next one is just
 128          * at the end of the first bitmap.
 129          */
 130         next_bitmap_offset = (u64)(BITS_PER_BITMAP * sectorsize);
 131
 132         /* Test a bit straddling two bitmaps */
 133         ret = test_add_free_space_entry(cache, next_bitmap_offset - SZ_2M,
 134                                         SZ_4M, 1);
 135         if (ret) {
 136                 test_err("couldn't add space that straddles two bitmaps %d",
 137                                 ret);
 138                 return ret;
 139         }
 140
 141         ret = btrfs_remove_free_space(cache, next_bitmap_offset - SZ_1M, SZ_2M);
 142         if (ret) {
 143                 test_err("couldn't remove overlapping space %d", ret);
 144                 return ret;
 145         }
 146
 147         if (test_check_exists(cache, next_bitmap_offset - SZ_1M, SZ_2M)) {
 148                 test_err("left some space when removing overlapping");
 149                 return -1;
 150         }
 151
 152         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 153
 154         return 0;
 155 }
 156
 157 /* This is the high grade jackassery */
 158 static int test_bitmaps_and_extents(struct btrfs_block_group *cache,
 159                                     u32 sectorsize)
 160 {
 161         u64 bitmap_offset = (u64)(BITS_PER_BITMAP * sectorsize);
 162         int ret;
 163
 164         test_msg("running bitmap and extent tests");
 165
 166         /*
 167          * First let's do something simple, an extent at the same offset as the
 168          * bitmap, but the free space completely in the extent and then
 169          * completely in the bitmap.
 170          */
 171         ret = test_add_free_space_entry(cache, SZ_4M, SZ_1M, 1);
 172         if (ret) {
 173                 test_err("couldn't create bitmap entry %d", ret);
 174                 return ret;
 175         }
 176
 177         ret = test_add_free_space_entry(cache, 0, SZ_1M, 0);
 178         if (ret) {
 179                 test_err("couldn't add extent entry %d", ret);
 180                 return ret;
 181         }
 182
 183         ret = btrfs_remove_free_space(cache, 0, SZ_1M);
 184         if (ret) {
 185                 test_err("couldn't remove extent entry %d", ret);
 186                 return ret;
 187         }
 188
 189         if (test_check_exists(cache, 0, SZ_1M)) {
 190                 test_err("left remnants after our remove");
 191                 return -1;
 192         }
 193
 194         /* Now to add back the extent entry and remove from the bitmap */
 195         ret = test_add_free_space_entry(cache, 0, SZ_1M, 0);
 196         if (ret) {
 197                 test_err("couldn't re-add extent entry %d", ret);
 198                 return ret;
 199         }
 200
 201         ret = btrfs_remove_free_space(cache, SZ_4M, SZ_1M);
 202         if (ret) {
 203                 test_err("couldn't remove from bitmap %d", ret);
 204                 return ret;
 205         }
 206
 207         if (test_check_exists(cache, SZ_4M, SZ_1M)) {
 208                 test_err("left remnants in the bitmap");
 209                 return -1;
 210         }
 211
 212         /*
 213          * Ok so a little more evil, extent entry and bitmap at the same offset,
 214          * removing an overlapping chunk.
 215          */
 216         ret = test_add_free_space_entry(cache, SZ_1M, SZ_4M, 1);
 217         if (ret) {
 218                 test_err("couldn't add to a bitmap %d", ret);
 219                 return ret;
 220         }
 221
 222         ret = btrfs_remove_free_space(cache, SZ_512K, 3 * SZ_1M);
 223         if (ret) {
 224                 test_err("couldn't remove overlapping space %d", ret);
 225                 return ret;
 226         }
 227
 228         if (test_check_exists(cache, SZ_512K, 3 * SZ_1M)) {
 229                 test_err("left over pieces after removing overlapping");
 230                 return -1;
 231         }
 232
 233         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 234
 235         /* Now with the extent entry offset into the bitmap */
 236         ret = test_add_free_space_entry(cache, SZ_4M, SZ_4M, 1);
 237         if (ret) {
 238                 test_err("couldn't add space to the bitmap %d", ret);
 239                 return ret;
 240         }
 241
 242         ret = test_add_free_space_entry(cache, SZ_2M, SZ_2M, 0);
 243         if (ret) {
 244                 test_err("couldn't add extent to the cache %d", ret);
 245                 return ret;
 246         }
 247
 248         ret = btrfs_remove_free_space(cache, 3 * SZ_1M, SZ_4M);
 249         if (ret) {
 250                 test_err("problem removing overlapping space %d", ret);
 251                 return ret;
 252         }
 253
 254         if (test_check_exists(cache, 3 * SZ_1M, SZ_4M)) {
 255                 test_err("left something behind when removing space");
 256                 return -1;
 257         }
 258
 259         /*
 260          * This has blown up in the past, the extent entry starts before the
 261          * bitmap entry, but we're trying to remove an offset that falls
 262          * completely within the bitmap range and is in both the extent entry
 263          * and the bitmap entry, looks like this
 264          *
 265          *   [ extent ]
 266          *      [ bitmap ]
 267          *        [ del ]
 268          */
 269         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 270         ret = test_add_free_space_entry(cache, bitmap_offset + SZ_4M, SZ_4M, 1);
 271         if (ret) {
 272                 test_err("couldn't add bitmap %d", ret);
 273                 return ret;
 274         }
 275
 276         ret = test_add_free_space_entry(cache, bitmap_offset - SZ_1M,
 277                                         5 * SZ_1M, 0);
 278         if (ret) {
 279                 test_err("couldn't add extent entry %d", ret);
 280                 return ret;
 281         }
 282
 283         ret = btrfs_remove_free_space(cache, bitmap_offset + SZ_1M, 5 * SZ_1M);
 284         if (ret) {
 285                 test_err("failed to free our space %d", ret);
 286                 return ret;
 287         }
 288
 289         if (test_check_exists(cache, bitmap_offset + SZ_1M, 5 * SZ_1M)) {
 290                 test_err("left stuff over");
 291                 return -1;
 292         }
 293
 294         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 295
 296         /*
 297          * This blew up before, we have part of the free space in a bitmap and
 298          * then the entirety of the rest of the space in an extent.  This used
 299          * to return -EAGAIN back from btrfs_remove_extent, make sure this
 300          * doesn't happen.
 301          */
 302         ret = test_add_free_space_entry(cache, SZ_1M, SZ_2M, 1);
 303         if (ret) {
 304                 test_err("couldn't add bitmap entry %d", ret);
 305                 return ret;
 306         }
 307
 308         ret = test_add_free_space_entry(cache, 3 * SZ_1M, SZ_1M, 0);
 309         if (ret) {
 310                 test_err("couldn't add extent entry %d", ret);
 311                 return ret;
 312         }
 313
 314         ret = btrfs_remove_free_space(cache, SZ_1M, 3 * SZ_1M);
 315         if (ret) {
 316                 test_err("error removing bitmap and extent overlapping %d", ret);
 317                 return ret;
 318         }
 319
 320         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 321         return 0;
 322 }
 323
 324 /* Used by test_steal_space_from_bitmap_to_extent(). */
 325 static bool test_use_bitmap(struct btrfs_free_space_ctl *ctl,
 326                             struct btrfs_free_space *info)
 327 {
 328         return ctl->free_extents > 0;
 329 }
 330
 331 /* Used by test_steal_space_from_bitmap_to_extent(). */
 332 static int
 333 check_num_extents_and_bitmaps(const struct btrfs_block_group *cache,
 334                               const int num_extents,
 335                               const int num_bitmaps)
 336 {
 337         if (cache->free_space_ctl->free_extents != num_extents) {
 338                 test_err(
 339                 "incorrect # of extent entries in the cache: %d, expected %d",
 340                          cache->free_space_ctl->free_extents, num_extents);
 341                 return -EINVAL;
 342         }
 343         if (cache->free_space_ctl->total_bitmaps != num_bitmaps) {
 344                 test_err(
 345                 "incorrect # of extent entries in the cache: %d, expected %d",
 346                          cache->free_space_ctl->total_bitmaps, num_bitmaps);
 347                 return -EINVAL;
 348         }
 349         return 0;
 350 }
 351
 352 /* Used by test_steal_space_from_bitmap_to_extent(). */
 353 static int check_cache_empty(struct btrfs_block_group *cache)
 354 {
 355         u64 offset;
 356         u64 max_extent_size;
 357
 358         /*
 359          * Now lets confirm that there's absolutely no free space left to
 360          * allocate.
 361          */
 362         if (cache->free_space_ctl->free_space != 0) {
 363                 test_err("cache free space is not 0");
 364                 return -EINVAL;
 365         }
 366
 367         /* And any allocation request, no matter how small, should fail now. */
 368         offset = btrfs_find_space_for_alloc(cache, 0, 4096, 0,
 369                                             &max_extent_size);
 370         if (offset != 0) {
 371                 test_err("space allocation did not fail, returned offset: %llu",
 372                          offset);
 373                 return -EINVAL;
 374         }
 375
 376         /* And no extent nor bitmap entries in the cache anymore. */
 377         return check_num_extents_and_bitmaps(cache, 0, 0);
 378 }
 379
 380 /*
 381  * Before we were able to steal free space from a bitmap entry to an extent
 382  * entry, we could end up with 2 entries representing a contiguous free space.
 383  * One would be an extent entry and the other a bitmap entry. Since in order
 384  * to allocate space to a caller we use only 1 entry, we couldn't return that
 385  * whole range to the caller if it was requested. This forced the caller to
 386  * either assume ENOSPC or perform several smaller space allocations, which
 387  * wasn't optimal as they could be spread all over the block group while under
 388  * concurrency (extra overhead and fragmentation).
 389  *
 390  * This stealing approach is beneficial, since we always prefer to allocate
 391  * from extent entries, both for clustered and non-clustered allocation
 392  * requests.
 393  */
 394 static int
 395 test_steal_space_from_bitmap_to_extent(struct btrfs_block_group *cache,
 396                                        u32 sectorsize)
 397 {
 398         int ret;
 399         u64 offset;
 400         u64 max_extent_size;
 401         const struct btrfs_free_space_op test_free_space_ops = {
 402                 .use_bitmap = test_use_bitmap,
 403         };
 404         const struct btrfs_free_space_op *orig_free_space_ops;
 405
 406         test_msg("running space stealing from bitmap to extent tests");
 407
 408         /*
 409          * For this test, we want to ensure we end up with an extent entry
 410          * immediately adjacent to a bitmap entry, where the bitmap starts
 411          * at an offset where the extent entry ends. We keep adding and
 412          * removing free space to reach into this state, but to get there
 413          * we need to reach a point where marking new free space doesn't
 414          * result in adding new extent entries or merging the new space
 415          * with existing extent entries - the space ends up being marked
 416          * in an existing bitmap that covers the new free space range.
 417          *
 418          * To get there, we need to reach the threshold defined set at
 419          * cache->free_space_ctl->extents_thresh, which currently is
 420          * 256 extents on a x86_64 system at least, and a few other
 421          * conditions (check free_space_cache.c). Instead of making the
 422          * test much longer and complicated, use a "use_bitmap" operation
 423          * that forces use of bitmaps as soon as we have at least 1
 424          * extent entry.
 425          */
 426         orig_free_space_ops = cache->free_space_ctl->op;
 427         cache->free_space_ctl->op = &test_free_space_ops;
 428
 429         /*
 430          * Extent entry covering free space range [128Mb - 256Kb, 128Mb - 128Kb[
 431          */
 432         ret = test_add_free_space_entry(cache, SZ_128M - SZ_256K, SZ_128K, 0);
 433         if (ret) {
 434                 test_err("couldn't add extent entry %d", ret);
 435                 return ret;
 436         }
 437
 438         /* Bitmap entry covering free space range [128Mb + 512Kb, 256Mb[ */
 439         ret = test_add_free_space_entry(cache, SZ_128M + SZ_512K,
 440                                         SZ_128M - SZ_512K, 1);
 441         if (ret) {
 442                 test_err("couldn't add bitmap entry %d", ret);
 443                 return ret;
 444         }
 445
 446         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 447         if (ret)
 448                 return ret;
 449
 450         /*
 451          * Now make only the first 256Kb of the bitmap marked as free, so that
 452          * we end up with only the following ranges marked as free space:
 453          *
 454          * [128Mb - 256Kb, 128Mb - 128Kb[
 455          * [128Mb + 512Kb, 128Mb + 768Kb[
 456          */
 457         ret = btrfs_remove_free_space(cache,
 458                                       SZ_128M + 768 * SZ_1K,
 459                                       SZ_128M - 768 * SZ_1K);
 460         if (ret) {
 461                 test_err("failed to free part of bitmap space %d", ret);
 462                 return ret;
 463         }
 464
 465         /* Confirm that only those 2 ranges are marked as free. */
 466         if (!test_check_exists(cache, SZ_128M - SZ_256K, SZ_128K)) {
 467                 test_err("free space range missing");
 468                 return -ENOENT;
 469         }
 470         if (!test_check_exists(cache, SZ_128M + SZ_512K, SZ_256K)) {
 471                 test_err("free space range missing");
 472                 return -ENOENT;
 473         }
 474
 475         /*
 476          * Confirm that the bitmap range [128Mb + 768Kb, 256Mb[ isn't marked
 477          * as free anymore.
 478          */
 479         if (test_check_exists(cache, SZ_128M + 768 * SZ_1K,
 480                               SZ_128M - 768 * SZ_1K)) {
 481                 test_err("bitmap region not removed from space cache");
 482                 return -EINVAL;
 483         }
 484
 485         /*
 486          * Confirm that the region [128Mb + 256Kb, 128Mb + 512Kb[, which is
 487          * covered by the bitmap, isn't marked as free.
 488          */
 489         if (test_check_exists(cache, SZ_128M + SZ_256K, SZ_256K)) {
 490                 test_err("invalid bitmap region marked as free");
 491                 return -EINVAL;
 492         }
 493
 494         /*
 495          * Confirm that the region [128Mb, 128Mb + 256Kb[, which is covered
 496          * by the bitmap too, isn't marked as free either.
 497          */
 498         if (test_check_exists(cache, SZ_128M, SZ_256K)) {
 499                 test_err("invalid bitmap region marked as free");
 500                 return -EINVAL;
 501         }
 502
 503         /*
 504          * Now lets mark the region [128Mb, 128Mb + 512Kb[ as free too. But,
 505          * lets make sure the free space cache marks it as free in the bitmap,
 506          * and doesn't insert a new extent entry to represent this region.
 507          */
 508         ret = btrfs_add_free_space(cache, SZ_128M, SZ_512K);
 509         if (ret) {
 510                 test_err("error adding free space: %d", ret);
 511                 return ret;
 512         }
 513         /* Confirm the region is marked as free. */
 514         if (!test_check_exists(cache, SZ_128M, SZ_512K)) {
 515                 test_err("bitmap region not marked as free");
 516                 return -ENOENT;
 517         }
 518
 519         /*
 520          * Confirm that no new extent entries or bitmap entries were added to
 521          * the cache after adding that free space region.
 522          */
 523         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 524         if (ret)
 525                 return ret;
 526
 527         /*
 528          * Now lets add a small free space region to the right of the previous
 529          * one, which is not contiguous with it and is part of the bitmap too.
 530          * The goal is to test that the bitmap entry space stealing doesn't
 531          * steal this space region.
 532          */
 533         ret = btrfs_add_free_space(cache, SZ_128M + SZ_16M, sectorsize);
 534         if (ret) {
 535                 test_err("error adding free space: %d", ret);
 536                 return ret;
 537         }
 538
 539         /*
 540          * Confirm that no new extent entries or bitmap entries were added to
 541          * the cache after adding that free space region.
 542          */
 543         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 544         if (ret)
 545                 return ret;
 546
 547         /*
 548          * Now mark the region [128Mb - 128Kb, 128Mb[ as free too. This will
 549          * expand the range covered by the existing extent entry that represents
 550          * the free space [128Mb - 256Kb, 128Mb - 128Kb[.
 551          */
 552         ret = btrfs_add_free_space(cache, SZ_128M - SZ_128K, SZ_128K);
 553         if (ret) {
 554                 test_err("error adding free space: %d", ret);
 555                 return ret;
 556         }
 557         /* Confirm the region is marked as free. */
 558         if (!test_check_exists(cache, SZ_128M - SZ_128K, SZ_128K)) {
 559                 test_err("extent region not marked as free");
 560                 return -ENOENT;
 561         }
 562
 563         /*
 564          * Confirm that our extent entry didn't stole all free space from the
 565          * bitmap, because of the small 4Kb free space region.
 566          */
 567         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 568         if (ret)
 569                 return ret;
 570
 571         /*
 572          * So now we have the range [128Mb - 256Kb, 128Mb + 768Kb[ as free
 573          * space. Without stealing bitmap free space into extent entry space,
 574          * we would have all this free space represented by 2 entries in the
 575          * cache:
 576          *
 577          * extent entry covering range: [128Mb - 256Kb, 128Mb[
 578          * bitmap entry covering range: [128Mb, 128Mb + 768Kb[
 579          *
 580          * Attempting to allocate the whole free space (1Mb) would fail, because
 581          * we can't allocate from multiple entries.
 582          * With the bitmap free space stealing, we get a single extent entry
 583          * that represents the 1Mb free space, and therefore we're able to
 584          * allocate the whole free space at once.
 585          */
 586         if (!test_check_exists(cache, SZ_128M - SZ_256K, SZ_1M)) {
 587                 test_err("expected region not marked as free");
 588                 return -ENOENT;
 589         }
 590
 591         if (cache->free_space_ctl->free_space != (SZ_1M + sectorsize)) {
 592                 test_err("cache free space is not 1Mb + %u", sectorsize);
 593                 return -EINVAL;
 594         }
 595
 596         offset = btrfs_find_space_for_alloc(cache,
 597                                             0, SZ_1M, 0,
 598                                             &max_extent_size);
 599         if (offset != (SZ_128M - SZ_256K)) {
 600                 test_err(
 601         "failed to allocate 1Mb from space cache, returned offset is: %llu",
 602                          offset);
 603                 return -EINVAL;
 604         }
 605
 606         /*
 607          * All that remains is a sectorsize free space region in a bitmap.
 608          * Confirm.
 609          */
 610         ret = check_num_extents_and_bitmaps(cache, 1, 1);
 611         if (ret)
 612                 return ret;
 613
 614         if (cache->free_space_ctl->free_space != sectorsize) {
 615                 test_err("cache free space is not %u", sectorsize);
 616                 return -EINVAL;
 617         }
 618
 619         offset = btrfs_find_space_for_alloc(cache,
 620                                             0, sectorsize, 0,
 621                                             &max_extent_size);
 622         if (offset != (SZ_128M + SZ_16M)) {
 623                 test_err("failed to allocate %u, returned offset : %llu",
 624                          sectorsize, offset);
 625                 return -EINVAL;
 626         }
 627
 628         ret = check_cache_empty(cache);
 629         if (ret)
 630                 return ret;
 631
 632         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 633
 634         /*
 635          * Now test a similar scenario, but where our extent entry is located
 636          * to the right of the bitmap entry, so that we can check that stealing
 637          * space from a bitmap to the front of an extent entry works.
 638          */
 639
 640         /*
 641          * Extent entry covering free space range [128Mb + 128Kb, 128Mb + 256Kb[
 642          */
 643         ret = test_add_free_space_entry(cache, SZ_128M + SZ_128K, SZ_128K, 0);
 644         if (ret) {
 645                 test_err("couldn't add extent entry %d", ret);
 646                 return ret;
 647         }
 648
 649         /* Bitmap entry covering free space range [0, 128Mb - 512Kb[ */
 650         ret = test_add_free_space_entry(cache, 0, SZ_128M - SZ_512K, 1);
 651         if (ret) {
 652                 test_err("couldn't add bitmap entry %d", ret);
 653                 return ret;
 654         }
 655
 656         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 657         if (ret)
 658                 return ret;
 659
 660         /*
 661          * Now make only the last 256Kb of the bitmap marked as free, so that
 662          * we end up with only the following ranges marked as free space:
 663          *
 664          * [128Mb + 128b, 128Mb + 256Kb[
 665          * [128Mb - 768Kb, 128Mb - 512Kb[
 666          */
 667         ret = btrfs_remove_free_space(cache, 0, SZ_128M - 768 * SZ_1K);
 668         if (ret) {
 669                 test_err("failed to free part of bitmap space %d", ret);
 670                 return ret;
 671         }
 672
 673         /* Confirm that only those 2 ranges are marked as free. */
 674         if (!test_check_exists(cache, SZ_128M + SZ_128K, SZ_128K)) {
 675                 test_err("free space range missing");
 676                 return -ENOENT;
 677         }
 678         if (!test_check_exists(cache, SZ_128M - 768 * SZ_1K, SZ_256K)) {
 679                 test_err("free space range missing");
 680                 return -ENOENT;
 681         }
 682
 683         /*
 684          * Confirm that the bitmap range [0, 128Mb - 768Kb[ isn't marked
 685          * as free anymore.
 686          */
 687         if (test_check_exists(cache, 0, SZ_128M - 768 * SZ_1K)) {
 688                 test_err("bitmap region not removed from space cache");
 689                 return -EINVAL;
 690         }
 691
 692         /*
 693          * Confirm that the region [128Mb - 512Kb, 128Mb[, which is
 694          * covered by the bitmap, isn't marked as free.
 695          */
 696         if (test_check_exists(cache, SZ_128M - SZ_512K, SZ_512K)) {
 697                 test_err("invalid bitmap region marked as free");
 698                 return -EINVAL;
 699         }
 700
 701         /*
 702          * Now lets mark the region [128Mb - 512Kb, 128Mb[ as free too. But,
 703          * lets make sure the free space cache marks it as free in the bitmap,
 704          * and doesn't insert a new extent entry to represent this region.
 705          */
 706         ret = btrfs_add_free_space(cache, SZ_128M - SZ_512K, SZ_512K);
 707         if (ret) {
 708                 test_err("error adding free space: %d", ret);
 709                 return ret;
 710         }
 711         /* Confirm the region is marked as free. */
 712         if (!test_check_exists(cache, SZ_128M - SZ_512K, SZ_512K)) {
 713                 test_err("bitmap region not marked as free");
 714                 return -ENOENT;
 715         }
 716
 717         /*
 718          * Confirm that no new extent entries or bitmap entries were added to
 719          * the cache after adding that free space region.
 720          */
 721         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 722         if (ret)
 723                 return ret;
 724
 725         /*
 726          * Now lets add a small free space region to the left of the previous
 727          * one, which is not contiguous with it and is part of the bitmap too.
 728          * The goal is to test that the bitmap entry space stealing doesn't
 729          * steal this space region.
 730          */
 731         ret = btrfs_add_free_space(cache, SZ_32M, 2 * sectorsize);
 732         if (ret) {
 733                 test_err("error adding free space: %d", ret);
 734                 return ret;
 735         }
 736
 737         /*
 738          * Now mark the region [128Mb, 128Mb + 128Kb[ as free too. This will
 739          * expand the range covered by the existing extent entry that represents
 740          * the free space [128Mb + 128Kb, 128Mb + 256Kb[.
 741          */
 742         ret = btrfs_add_free_space(cache, SZ_128M, SZ_128K);
 743         if (ret) {
 744                 test_err("error adding free space: %d", ret);
 745                 return ret;
 746         }
 747         /* Confirm the region is marked as free. */
 748         if (!test_check_exists(cache, SZ_128M, SZ_128K)) {
 749                 test_err("extent region not marked as free");
 750                 return -ENOENT;
 751         }
 752
 753         /*
 754          * Confirm that our extent entry didn't stole all free space from the
 755          * bitmap, because of the small 2 * sectorsize free space region.
 756          */
 757         ret = check_num_extents_and_bitmaps(cache, 2, 1);
 758         if (ret)
 759                 return ret;
 760
 761         /*
 762          * So now we have the range [128Mb - 768Kb, 128Mb + 256Kb[ as free
 763          * space. Without stealing bitmap free space into extent entry space,
 764          * we would have all this free space represented by 2 entries in the
 765          * cache:
 766          *
 767          * extent entry covering range: [128Mb, 128Mb + 256Kb[
 768          * bitmap entry covering range: [128Mb - 768Kb, 128Mb[
 769          *
 770          * Attempting to allocate the whole free space (1Mb) would fail, because
 771          * we can't allocate from multiple entries.
 772          * With the bitmap free space stealing, we get a single extent entry
 773          * that represents the 1Mb free space, and therefore we're able to
 774          * allocate the whole free space at once.
 775          */
 776         if (!test_check_exists(cache, SZ_128M - 768 * SZ_1K, SZ_1M)) {
 777                 test_err("expected region not marked as free");
 778                 return -ENOENT;
 779         }
 780
 781         if (cache->free_space_ctl->free_space != (SZ_1M + 2 * sectorsize)) {
 782                 test_err("cache free space is not 1Mb + %u", 2 * sectorsize);
 783                 return -EINVAL;
 784         }
 785
 786         offset = btrfs_find_space_for_alloc(cache, 0, SZ_1M, 0,
 787                                             &max_extent_size);
 788         if (offset != (SZ_128M - 768 * SZ_1K)) {
 789                 test_err(
 790         "failed to allocate 1Mb from space cache, returned offset is: %llu",
 791                          offset);
 792                 return -EINVAL;
 793         }
 794
 795         /*
 796          * All that remains is 2 * sectorsize free space region
 797          * in a bitmap. Confirm.
 798          */
 799         ret = check_num_extents_and_bitmaps(cache, 1, 1);
 800         if (ret)
 801                 return ret;
 802
 803         if (cache->free_space_ctl->free_space != 2 * sectorsize) {
 804                 test_err("cache free space is not %u", 2 * sectorsize);
 805                 return -EINVAL;
 806         }
 807
 808         offset = btrfs_find_space_for_alloc(cache,
 809                                             0, 2 * sectorsize, 0,
 810                                             &max_extent_size);
 811         if (offset != SZ_32M) {
 812                 test_err("failed to allocate %u, offset: %llu",
 813                          2 * sectorsize, offset);
 814                 return -EINVAL;
 815         }
 816
 817         ret = check_cache_empty(cache);
 818         if (ret)
 819                 return ret;
 820
 821         cache->free_space_ctl->op = orig_free_space_ops;
 822         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 823
 824         return 0;
 825 }
 826
 827 int btrfs_test_free_space_cache(u32 sectorsize, u32 nodesize)
 828 {
 829         struct btrfs_fs_info *fs_info;
 830         struct btrfs_block_group *cache;
 831         struct btrfs_root *root = NULL;
 832         int ret = -ENOMEM;
 833
 834         test_msg("running btrfs free space cache tests");
 835         fs_info = btrfs_alloc_dummy_fs_info(nodesize, sectorsize);
 836         if (!fs_info) {
 837                 test_std_err(TEST_ALLOC_FS_INFO);
 838                 return -ENOMEM;
 839         }
 840
 841         /*
 842          * For ppc64 (with 64k page size), bytes per bitmap might be
 843          * larger than 1G.  To make bitmap test available in ppc64,
 844          * alloc dummy block group whose size cross bitmaps.
 845          */
 846         cache = btrfs_alloc_dummy_block_group(fs_info,
 847                                       BITS_PER_BITMAP * sectorsize + PAGE_SIZE);
 848         if (!cache) {
 849                 test_std_err(TEST_ALLOC_BLOCK_GROUP);
 850                 btrfs_free_dummy_fs_info(fs_info);
 851                 return 0;
 852         }
 853
 854         root = btrfs_alloc_dummy_root(fs_info);
 855         if (IS_ERR(root)) {
 856                 test_std_err(TEST_ALLOC_ROOT);
 857                 ret = PTR_ERR(root);
 858                 goto out;
 859         }
 860
 861         root->fs_info->extent_root = root;
 862
 863         ret = test_extents(cache);
 864         if (ret)
 865                 goto out;
 866         ret = test_bitmaps(cache, sectorsize);
 867         if (ret)
 868                 goto out;
 869         ret = test_bitmaps_and_extents(cache, sectorsize);
 870         if (ret)
 871                 goto out;
 872
 873         ret = test_steal_space_from_bitmap_to_extent(cache, sectorsize);
 874 out:
 875         btrfs_free_dummy_block_group(cache);
 876         btrfs_free_dummy_root(root);
 877         btrfs_free_dummy_fs_info(fs_info);
 878         return ret;
 879 }