sys/cddl/contrib/opensolaris/uts/common/fs/zfs/range_tree.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25 /*
  26  * Copyright (c) 2013, 2017 by Delphix. All rights reserved.
  27  */
  28
  29 #include <sys/zfs_context.h>
  30 #include <sys/spa.h>
  31 #include <sys/dmu.h>
  32 #include <sys/dnode.h>
  33 #include <sys/zio.h>
  34 #include <sys/range_tree.h>
  35
  36 /*
  37  * Range trees are tree-based data structures that can be used to
  38  * track free space or generally any space allocation information.
  39  * A range tree keeps track of individual segments and automatically
  40  * provides facilities such as adjacent extent merging and extent
  41  * splitting in response to range add/remove requests.
  42  *
  43  * A range tree starts out completely empty, with no segments in it.
  44  * Adding an allocation via range_tree_add to the range tree can either:
  45  * 1) create a new extent
  46  * 2) extend an adjacent extent
  47  * 3) merge two adjacent extents
  48  * Conversely, removing an allocation via range_tree_remove can:
  49  * 1) completely remove an extent
  50  * 2) shorten an extent (if the allocation was near one of its ends)
  51  * 3) split an extent into two extents, in effect punching a hole
  52  *
  53  * A range tree is also capable of 'bridging' gaps when adding
  54  * allocations. This is useful for cases when close proximity of
  55  * allocations is an important detail that needs to be represented
  56  * in the range tree. See range_tree_set_gap(). The default behavior
  57  * is not to bridge gaps (i.e. the maximum allowed gap size is 0).
  58  *
  59  * In order to traverse a range tree, use either the range_tree_walk()
  60  * or range_tree_vacate() functions.
  61  *
  62  * To obtain more accurate information on individual segment
  63  * operations that the range tree performs "under the hood", you can
  64  * specify a set of callbacks by passing a range_tree_ops_t structure
  65  * to the range_tree_create function. Any callbacks that are non-NULL
  66  * are then called at the appropriate times.
  67  *
  68  * The range tree code also supports a special variant of range trees
  69  * that can bridge small gaps between segments. This kind of tree is used
  70  * by the dsl scanning code to group I/Os into mostly sequential chunks to
  71  * optimize disk performance. The code here attempts to do this with as
  72  * little memory and computational overhead as possible. One limitation of
  73  * this implementation is that segments of range trees with gaps can only
  74  * support removing complete segments.
  75  */
  76
  77 kmem_cache_t *range_seg_cache;
  78
  79 /* Generic ops for managing an AVL tree alongside a range tree */
  80 struct range_tree_ops rt_avl_ops = {
  81         .rtop_create = rt_avl_create,
  82         .rtop_destroy = rt_avl_destroy,
  83         .rtop_add = rt_avl_add,
  84         .rtop_remove = rt_avl_remove,
  85         .rtop_vacate = rt_avl_vacate,
  86 };
  87
  88 void
  89 range_tree_init(void)
  90 {
  91         ASSERT(range_seg_cache == NULL);
  92         range_seg_cache = kmem_cache_create("range_seg_cache",
  93             sizeof (range_seg_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  94 }
  95
  96 void
  97 range_tree_fini(void)
  98 {
  99         kmem_cache_destroy(range_seg_cache);
 100         range_seg_cache = NULL;
 101 }
 102
 103 void
 104 range_tree_stat_verify(range_tree_t *rt)
 105 {
 106         range_seg_t *rs;
 107         uint64_t hist[RANGE_TREE_HISTOGRAM_SIZE] = { 0 };
 108         int i;
 109
 110         for (rs = avl_first(&rt->rt_root); rs != NULL;
 111             rs = AVL_NEXT(&rt->rt_root, rs)) {
 112                 uint64_t size = rs->rs_end - rs->rs_start;
 113                 int idx = highbit64(size) - 1;
 114
 115                 hist[idx]++;
 116                 ASSERT3U(hist[idx], !=, 0);
 117         }
 118
 119         for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
 120                 if (hist[i] != rt->rt_histogram[i]) {
 121                         zfs_dbgmsg("i=%d, hist=%p, hist=%llu, rt_hist=%llu",
 122                             i, hist, hist[i], rt->rt_histogram[i]);
 123                 }
 124                 VERIFY3U(hist[i], ==, rt->rt_histogram[i]);
 125         }
 126 }
 127
 128 static void
 129 range_tree_stat_incr(range_tree_t *rt, range_seg_t *rs)
 130 {
 131         uint64_t size = rs->rs_end - rs->rs_start;
 132         int idx = highbit64(size) - 1;
 133
 134         ASSERT(size != 0);
 135         ASSERT3U(idx, <,
 136             sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));
 137
 138         rt->rt_histogram[idx]++;
 139         ASSERT3U(rt->rt_histogram[idx], !=, 0);
 140 }
 141
 142 static void
 143 range_tree_stat_decr(range_tree_t *rt, range_seg_t *rs)
 144 {
 145         uint64_t size = rs->rs_end - rs->rs_start;
 146         int idx = highbit64(size) - 1;
 147
 148         ASSERT(size != 0);
 149         ASSERT3U(idx, <,
 150             sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));
 151
 152         ASSERT3U(rt->rt_histogram[idx], !=, 0);
 153         rt->rt_histogram[idx]--;
 154 }
 155
 156 /*
 157  * NOTE: caller is responsible for all locking.
 158  */
 159 static int
 160 range_tree_seg_compare(const void *x1, const void *x2)
 161 {
 162         const range_seg_t *r1 = (const range_seg_t *)x1;
 163         const range_seg_t *r2 = (const range_seg_t *)x2;
 164
 165         ASSERT3U(r1->rs_start, <=, r1->rs_end);
 166         ASSERT3U(r2->rs_start, <=, r2->rs_end);
 167
 168         return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
 169 }
 170
 171 range_tree_t *
 172 range_tree_create_impl(range_tree_ops_t *ops, void *arg,
 173     int (*avl_compare) (const void *, const void *), uint64_t gap)
 174 {
 175         range_tree_t *rt = kmem_zalloc(sizeof (range_tree_t), KM_SLEEP);
 176
 177         avl_create(&rt->rt_root, range_tree_seg_compare,
 178             sizeof (range_seg_t), offsetof(range_seg_t, rs_node));
 179
 180         rt->rt_ops = ops;
 181         rt->rt_arg = arg;
 182         rt->rt_gap = gap;
 183         rt->rt_avl_compare = avl_compare;
 184
 185         if (rt->rt_ops != NULL && rt->rt_ops->rtop_create != NULL)
 186                 rt->rt_ops->rtop_create(rt, rt->rt_arg);
 187
 188         return (rt);
 189 }
 190
 191 range_tree_t *
 192 range_tree_create(range_tree_ops_t *ops, void *arg)
 193 {
 194         return (range_tree_create_impl(ops, arg, NULL, 0));
 195 }
 196
 197 void
 198 range_tree_destroy(range_tree_t *rt)
 199 {
 200         VERIFY0(rt->rt_space);
 201
 202         if (rt->rt_ops != NULL && rt->rt_ops->rtop_destroy != NULL)
 203                 rt->rt_ops->rtop_destroy(rt, rt->rt_arg);
 204
 205         avl_destroy(&rt->rt_root);
 206         kmem_free(rt, sizeof (*rt));
 207 }
 208
 209 void
 210 range_tree_adjust_fill(range_tree_t *rt, range_seg_t *rs, int64_t delta)
 211 {
 212         ASSERT3U(rs->rs_fill + delta, !=, 0);
 213         ASSERT3U(rs->rs_fill + delta, <=, rs->rs_end - rs->rs_start);
 214
 215         if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 216                 rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
 217         rs->rs_fill += delta;
 218         if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
 219                 rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
 220 }
 221
 222 static void
 223 range_tree_add_impl(void *arg, uint64_t start, uint64_t size, uint64_t fill)
 224 {
 225         range_tree_t *rt = arg;
 226         avl_index_t where;
 227         range_seg_t rsearch, *rs_before, *rs_after, *rs;
 228         uint64_t end = start + size, gap = rt->rt_gap;
 229         uint64_t bridge_size = 0;
 230         boolean_t merge_before, merge_after;
 231
 232         ASSERT3U(size, !=, 0);
 233         ASSERT3U(fill, <=, size);
 234
 235         rsearch.rs_start = start;
 236         rsearch.rs_end = end;
 237         rs = avl_find(&rt->rt_root, &rsearch, &where);
 238
 239         if (gap == 0 && rs != NULL &&
 240             rs->rs_start <= start && rs->rs_end >= end) {
 241                 zfs_panic_recover("zfs: allocating allocated segment"
 242                     "(offset=%llu size=%llu) of (offset=%llu size=%llu)\n",
 243                     (longlong_t)start, (longlong_t)size,
 244                     (longlong_t)rs->rs_start,
 245                     (longlong_t)rs->rs_end - rs->rs_start);
 246                 return;
 247         }
 248
 249         /*
 250          * If this is a gap-supporting range tree, it is possible that we
 251          * are inserting into an existing segment. In this case simply
 252          * bump the fill count and call the remove / add callbacks. If the
 253          * new range will extend an existing segment, we remove the
 254          * existing one, apply the new extent to it and re-insert it using
 255          * the normal code paths.
 256          */
 257         if (rs != NULL) {
 258                 ASSERT3U(gap, !=, 0);
 259                 if (rs->rs_start <= start && rs->rs_end >= end) {
 260                         range_tree_adjust_fill(rt, rs, fill);
 261                         return;
 262                 }
 263
 264                 avl_remove(&rt->rt_root, rs);
 265                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 266                         rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
 267
 268                 range_tree_stat_decr(rt, rs);
 269                 rt->rt_space -= rs->rs_end - rs->rs_start;
 270
 271                 fill += rs->rs_fill;
 272                 start = MIN(start, rs->rs_start);
 273                 end = MAX(end, rs->rs_end);
 274                 size = end - start;
 275
 276                 range_tree_add_impl(rt, start, size, fill);
 277
 278                 kmem_cache_free(range_seg_cache, rs);
 279                 return;
 280         }
 281
 282         ASSERT3P(rs, ==, NULL);
 283
 284         /*
 285          * Determine whether or not we will have to merge with our neighbors.
 286          * If gap != 0, we might need to merge with our neighbors even if we
 287          * aren't directly touching.
 288          */
 289         rs_before = avl_nearest(&rt->rt_root, where, AVL_BEFORE);
 290         rs_after = avl_nearest(&rt->rt_root, where, AVL_AFTER);
 291
 292         merge_before = (rs_before != NULL && rs_before->rs_end >= start - gap);
 293         merge_after = (rs_after != NULL && rs_after->rs_start <= end + gap);
 294
 295         if (merge_before && gap != 0)
 296                 bridge_size += start - rs_before->rs_end;
 297         if (merge_after && gap != 0)
 298                 bridge_size += rs_after->rs_start - end;
 299
 300         if (merge_before && merge_after) {
 301                 avl_remove(&rt->rt_root, rs_before);
 302                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL) {
 303                         rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);
 304                         rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);
 305                 }
 306
 307                 range_tree_stat_decr(rt, rs_before);
 308                 range_tree_stat_decr(rt, rs_after);
 309
 310                 rs_after->rs_fill += rs_before->rs_fill + fill;
 311                 rs_after->rs_start = rs_before->rs_start;
 312                 kmem_cache_free(range_seg_cache, rs_before);
 313                 rs = rs_after;
 314         } else if (merge_before) {
 315                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 316                         rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);
 317
 318                 range_tree_stat_decr(rt, rs_before);
 319
 320                 rs_before->rs_fill += fill;
 321                 rs_before->rs_end = end;
 322                 rs = rs_before;
 323         } else if (merge_after) {
 324                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 325                         rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);
 326
 327                 range_tree_stat_decr(rt, rs_after);
 328
 329                 rs_after->rs_fill += fill;
 330                 rs_after->rs_start = start;
 331                 rs = rs_after;
 332         } else {
 333                 rs = kmem_cache_alloc(range_seg_cache, KM_SLEEP);
 334
 335                 rs->rs_fill = fill;
 336                 rs->rs_start = start;
 337                 rs->rs_end = end;
 338                 avl_insert(&rt->rt_root, rs, where);
 339         }
 340
 341         if (gap != 0)
 342                 ASSERT3U(rs->rs_fill, <=, rs->rs_end - rs->rs_start);
 343         else
 344                 ASSERT3U(rs->rs_fill, ==, rs->rs_end - rs->rs_start);
 345
 346         if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
 347                 rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
 348
 349         range_tree_stat_incr(rt, rs);
 350         rt->rt_space += size + bridge_size;
 351 }
 352
 353 void
 354 range_tree_add(void *arg, uint64_t start, uint64_t size)
 355 {
 356         range_tree_add_impl(arg, start, size, size);
 357 }
 358
 359 static void
 360 range_tree_remove_impl(range_tree_t *rt, uint64_t start, uint64_t size,
 361     boolean_t do_fill)
 362 {
 363         avl_index_t where;
 364         range_seg_t rsearch, *rs, *newseg;
 365         uint64_t end = start + size;
 366         boolean_t left_over, right_over;
 367
 368         VERIFY3U(size, !=, 0);
 369         VERIFY3U(size, <=, rt->rt_space);
 370
 371         rsearch.rs_start = start;
 372         rsearch.rs_end = end;
 373         rs = avl_find(&rt->rt_root, &rsearch, &where);
 374
 375         /* Make sure we completely overlap with someone */
 376         if (rs == NULL) {
 377                 zfs_panic_recover("zfs: freeing free segment "
 378                     "(offset=%llu size=%llu)",
 379                     (longlong_t)start, (longlong_t)size);
 380                 return;
 381         }
 382
 383         /*
 384          * Range trees with gap support must only remove complete segments
 385          * from the tree. This allows us to maintain accurate fill accounting
 386          * and to ensure that bridged sections are not leaked. If we need to
 387          * remove less than the full segment, we can only adjust the fill count.
 388          */
 389         if (rt->rt_gap != 0) {
 390                 if (do_fill) {
 391                         if (rs->rs_fill == size) {
 392                                 start = rs->rs_start;
 393                                 end = rs->rs_end;
 394                                 size = end - start;
 395                         } else {
 396                                 range_tree_adjust_fill(rt, rs, -size);
 397                                 return;
 398                         }
 399                 } else if (rs->rs_start != start || rs->rs_end != end) {
 400                         zfs_panic_recover("zfs: freeing partial segment of "
 401                             "gap tree (offset=%llu size=%llu) of "
 402                             "(offset=%llu size=%llu)",
 403                             (longlong_t)start, (longlong_t)size,
 404                             (longlong_t)rs->rs_start,
 405                             (longlong_t)rs->rs_end - rs->rs_start);
 406                         return;
 407                 }
 408         }
 409
 410         VERIFY3U(rs->rs_start, <=, start);
 411         VERIFY3U(rs->rs_end, >=, end);
 412
 413         left_over = (rs->rs_start != start);
 414         right_over = (rs->rs_end != end);
 415
 416         range_tree_stat_decr(rt, rs);
 417
 418         if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 419                 rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
 420
 421         if (left_over && right_over) {
 422                 newseg = kmem_cache_alloc(range_seg_cache, KM_SLEEP);
 423                 newseg->rs_start = end;
 424                 newseg->rs_end = rs->rs_end;
 425                 newseg->rs_fill = newseg->rs_end - newseg->rs_start;
 426                 range_tree_stat_incr(rt, newseg);
 427
 428                 rs->rs_end = start;
 429
 430                 avl_insert_here(&rt->rt_root, newseg, rs, AVL_AFTER);
 431                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
 432                         rt->rt_ops->rtop_add(rt, newseg, rt->rt_arg);
 433         } else if (left_over) {
 434                 rs->rs_end = start;
 435         } else if (right_over) {
 436                 rs->rs_start = end;
 437         } else {
 438                 avl_remove(&rt->rt_root, rs);
 439                 kmem_cache_free(range_seg_cache, rs);
 440                 rs = NULL;
 441         }
 442
 443         if (rs != NULL) {
 444                 /*
 445                  * The fill of the leftover segment will always be equal to
 446                  * the size, since we do not support removing partial segments
 447                  * of range trees with gaps.
 448                  */
 449                 rs->rs_fill = rs->rs_end - rs->rs_start;
 450                 range_tree_stat_incr(rt, rs);
 451
 452                 if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
 453                         rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
 454         }
 455
 456         rt->rt_space -= size;
 457 }
 458
 459 void
 460 range_tree_remove(void *arg, uint64_t start, uint64_t size)
 461 {
 462         range_tree_remove_impl(arg, start, size, B_FALSE);
 463 }
 464
 465 void
 466 range_tree_remove_fill(range_tree_t *rt, uint64_t start, uint64_t size)
 467 {
 468         range_tree_remove_impl(rt, start, size, B_TRUE);
 469 }
 470
 471 void
 472 range_tree_resize_segment(range_tree_t *rt, range_seg_t *rs,
 473     uint64_t newstart, uint64_t newsize)
 474 {
 475         int64_t delta = newsize - (rs->rs_end - rs->rs_start);
 476
 477         range_tree_stat_decr(rt, rs);
 478         if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
 479                 rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
 480
 481         rs->rs_start = newstart;
 482         rs->rs_end = newstart + newsize;
 483
 484         range_tree_stat_incr(rt, rs);
 485         if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
 486                 rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
 487
 488         rt->rt_space += delta;
 489 }
 490
 491 static range_seg_t *
 492 range_tree_find_impl(range_tree_t *rt, uint64_t start, uint64_t size)
 493 {
 494         range_seg_t rsearch;
 495         uint64_t end = start + size;
 496
 497         VERIFY(size != 0);
 498
 499         rsearch.rs_start = start;
 500         rsearch.rs_end = end;
 501         return (avl_find(&rt->rt_root, &rsearch, NULL));
 502 }
 503
 504 range_seg_t *
 505 range_tree_find(range_tree_t *rt, uint64_t start, uint64_t size)
 506 {
 507         range_seg_t *rs = range_tree_find_impl(rt, start, size);
 508         if (rs != NULL && rs->rs_start <= start && rs->rs_end >= start + size)
 509                 return (rs);
 510         return (NULL);
 511 }
 512
 513 void
 514 range_tree_verify_not_present(range_tree_t *rt, uint64_t off, uint64_t size)
 515 {
 516         range_seg_t *rs = range_tree_find(rt, off, size);
 517         if (rs != NULL)
 518                 panic("segment already in tree; rs=%p", (void *)rs);
 519 }
 520
 521 boolean_t
 522 range_tree_contains(range_tree_t *rt, uint64_t start, uint64_t size)
 523 {
 524         return (range_tree_find(rt, start, size) != NULL);
 525 }
 526
 527 /*
 528  * Ensure that this range is not in the tree, regardless of whether
 529  * it is currently in the tree.
 530  */
 531 void
 532 range_tree_clear(range_tree_t *rt, uint64_t start, uint64_t size)
 533 {
 534         range_seg_t *rs;
 535
 536         if (size == 0)
 537                 return;
 538
 539         while ((rs = range_tree_find_impl(rt, start, size)) != NULL) {
 540                 uint64_t free_start = MAX(rs->rs_start, start);
 541                 uint64_t free_end = MIN(rs->rs_end, start + size);
 542                 range_tree_remove(rt, free_start, free_end - free_start);
 543         }
 544 }
 545
 546 void
 547 range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst)
 548 {
 549         range_tree_t *rt;
 550
 551         ASSERT0(range_tree_space(*rtdst));
 552         ASSERT0(avl_numnodes(&(*rtdst)->rt_root));
 553
 554         rt = *rtsrc;
 555         *rtsrc = *rtdst;
 556         *rtdst = rt;
 557 }
 558
 559 void
 560 range_tree_vacate(range_tree_t *rt, range_tree_func_t *func, void *arg)
 561 {
 562         range_seg_t *rs;
 563         void *cookie = NULL;
 564
 565
 566         if (rt->rt_ops != NULL && rt->rt_ops->rtop_vacate != NULL)
 567                 rt->rt_ops->rtop_vacate(rt, rt->rt_arg);
 568
 569         while ((rs = avl_destroy_nodes(&rt->rt_root, &cookie)) != NULL) {
 570                 if (func != NULL)
 571                         func(arg, rs->rs_start, rs->rs_end - rs->rs_start);
 572                 kmem_cache_free(range_seg_cache, rs);
 573         }
 574
 575         bzero(rt->rt_histogram, sizeof (rt->rt_histogram));
 576         rt->rt_space = 0;
 577 }
 578
 579 void
 580 range_tree_walk(range_tree_t *rt, range_tree_func_t *func, void *arg)
 581 {
 582         range_seg_t *rs;
 583
 584         for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs))
 585                 func(arg, rs->rs_start, rs->rs_end - rs->rs_start);
 586 }
 587
 588 range_seg_t *
 589 range_tree_first(range_tree_t *rt)
 590 {
 591         return (avl_first(&rt->rt_root));
 592 }
 593
 594 uint64_t
 595 range_tree_space(range_tree_t *rt)
 596 {
 597         return (rt->rt_space);
 598 }
 599
 600 /* Generic range tree functions for maintaining segments in an AVL tree. */
 601 void
 602 rt_avl_create(range_tree_t *rt, void *arg)
 603 {
 604         avl_tree_t *tree = arg;
 605
 606         avl_create(tree, rt->rt_avl_compare, sizeof (range_seg_t),
 607             offsetof(range_seg_t, rs_pp_node));
 608 }
 609
 610 void
 611 rt_avl_destroy(range_tree_t *rt, void *arg)
 612 {
 613         avl_tree_t *tree = arg;
 614
 615         ASSERT0(avl_numnodes(tree));
 616         avl_destroy(tree);
 617 }
 618
 619 void
 620 rt_avl_add(range_tree_t *rt, range_seg_t *rs, void *arg)
 621 {
 622         avl_tree_t *tree = arg;
 623         avl_add(tree, rs);
 624 }
 625
 626 void
 627 rt_avl_remove(range_tree_t *rt, range_seg_t *rs, void *arg)
 628 {
 629         avl_tree_t *tree = arg;
 630         avl_remove(tree, rs);
 631 }
 632
 633 void
 634 rt_avl_vacate(range_tree_t *rt, void *arg)
 635 {
 636         /*
 637          * Normally one would walk the tree freeing nodes along the way.
 638          * Since the nodes are shared with the range trees we can avoid
 639          * walking all nodes and just reinitialize the avl tree. The nodes
 640          * will be freed by the range tree, so we don't want to free them here.
 641          */
 642         rt_avl_create(rt, arg);
 643 }
 644
 645 boolean_t
 646 range_tree_is_empty(range_tree_t *rt)
 647 {
 648         ASSERT(rt != NULL);
 649         return (range_tree_space(rt) == 0);
 650 }
 651
 652 uint64_t
 653 range_tree_min(range_tree_t *rt)
 654 {
 655         range_seg_t *rs = avl_first(&rt->rt_root);
 656         return (rs != NULL ? rs->rs_start : 0);
 657 }
 658
 659 uint64_t
 660 range_tree_max(range_tree_t *rt)
 661 {
 662         range_seg_t *rs = avl_last(&rt->rt_root);
 663         return (rs != NULL ? rs->rs_end : 0);
 664 }
 665
 666 uint64_t
 667 range_tree_span(range_tree_t *rt)
 668 {
 669         return (range_tree_max(rt) - range_tree_min(rt));
 670 }