vm_radix.c revision 228079
1/* 2 * Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org> 3 * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 30/* 31 * Radix tree implementation. 32 */ 33 34#include <sys/cdefs.h> 35 36#include <sys/param.h> 37#include <sys/conf.h> 38#include <sys/systm.h> 39#include <sys/kernel.h> 40#include <sys/malloc.h> 41#include <sys/queue.h> 42#include <sys/param.h> 43#include <sys/lock.h> 44#include <sys/mutex.h> 45#include <sys/ktr.h> 46#include <vm/uma.h> 47#include <vm/vm.h> 48#include <vm/vm_param.h> 49#include <vm/vm_extern.h> 50#include <vm/vm_kern.h> 51#include <vm/vm_page.h> 52#include <vm/vm_radix.h> 53#include <vm/vm_object.h> 54 55#include <sys/kdb.h> 56 57CTASSERT(sizeof(struct vm_radix_node) < PAGE_SIZE); 58 59static uma_zone_t vm_radix_node_zone; 60 61#ifndef UMA_MD_SMALL_ALLOC 62static void * 63vm_radix_node_zone_allocf(uma_zone_t zone, int size, uint8_t *flags, int wait) 64{ 65 vm_offset_t addr; 66 vm_page_t m; 67 int pflags; 68 69 /* Inform UMA that this allocator uses kernel_map. */ 70 *flags = UMA_SLAB_KERNEL; 71 72 pflags = VM_ALLOC_WIRED | VM_ALLOC_NOOBJ; 73 74 /* 75 * As kmem_alloc_nofault() can however fail, let just assume that 76 * M_NOWAIT is on and act accordingly. 77 */ 78 pflags |= ((wait & M_USE_RESERVE) != 0) ? VM_ALLOC_INTERRUPT : 79 VM_ALLOC_SYSTEM; 80 if ((wait & M_ZERO) != 0) 81 pflags |= VM_ALLOC_ZERO; 82 addr = kmem_alloc_nofault(kernel_map, size); 83 if (addr == 0) 84 return (NULL); 85 86 /* Just one page allocation is assumed here. */ 87 m = vm_page_alloc(NULL, OFF_TO_IDX(addr - VM_MIN_KERNEL_ADDRESS), 88 pflags); 89 if (m == NULL) { 90 kmem_free(kernel_map, addr, size); 91 return (NULL); 92 } 93 if ((wait & M_ZERO) != 0 && (m->flags & PG_ZERO) == 0) 94 pmap_zero_page(m); 95 pmap_qenter(addr, &m, 1); 96 return ((void *)addr); 97} 98 99static void 100vm_radix_node_zone_freef(void *item, int size, uint8_t flags) 101{ 102 vm_page_t m; 103 vm_offset_t voitem; 104 105 MPASS((flags & UMA_SLAB_KERNEL) != 0); 106 107 /* Just one page allocation is assumed here. */ 108 voitem = (vm_offset_t)item; 109 m = PHYS_TO_VM_PAGE(pmap_kextract(voitem)); 110 pmap_qremove(voitem, 1); 111 vm_page_free(m); 112 kmem_free(kernel_map, voitem, size); 113} 114 115static void 116init_vm_radix_alloc(void *dummy __unused) 117{ 118 119 uma_zone_set_allocf(vm_radix_node_zone, vm_radix_node_zone_allocf); 120 uma_zone_set_freef(vm_radix_node_zone, vm_radix_node_zone_freef); 121} 122SYSINIT(vm_radix, SI_SUB_KMEM, SI_ORDER_SECOND, init_vm_radix_alloc, NULL); 123#endif 124 125/* 126 * Radix node zone destructor. 127 */ 128#ifdef INVARIANTS 129static void 130vm_radix_node_zone_dtor(void *mem, int size, void *arg) 131{ 132 struct vm_radix_node *rnode; 133 134 rnode = mem; 135 KASSERT(rnode->rn_count == 0, 136 ("vm_radix_node_put: Freeing a node with %d children\n", 137 rnode->rn_count)); 138} 139#endif 140 141/* 142 * Allocate a radix node. Initializes all elements to 0. 143 */ 144static __inline struct vm_radix_node * 145vm_radix_node_get(void) 146{ 147 148 return (uma_zalloc(vm_radix_node_zone, M_NOWAIT | M_ZERO)); 149} 150 151/* 152 * Free radix node. 153 */ 154static __inline void 155vm_radix_node_put(struct vm_radix_node *rnode) 156{ 157 158 uma_zfree(vm_radix_node_zone, rnode); 159} 160 161/* 162 * Return the position in the array for a given level. 163 */ 164static __inline int 165vm_radix_slot(vm_pindex_t index, int level) 166{ 167 168 return ((index >> (level * VM_RADIX_WIDTH)) & VM_RADIX_MASK); 169} 170 171void 172vm_radix_init(void) 173{ 174 175 vm_radix_node_zone = uma_zcreate("RADIX NODE", 176 sizeof(struct vm_radix_node), NULL, 177#ifdef INVARIANTS 178 vm_radix_node_zone_dtor, 179#else 180 NULL, 181#endif 182 NULL, NULL, VM_RADIX_HEIGHT, UMA_ZONE_VM); 183} 184 185/* 186 * Extract the root node and height from a radix tree with a single load. 187 */ 188static __inline int 189vm_radix_height(struct vm_radix *rtree, struct vm_radix_node **rnode) 190{ 191 uintptr_t root; 192 int height; 193 194 root = rtree->rt_root; 195 height = root & VM_RADIX_HEIGHT; 196 *rnode = (struct vm_radix_node *)(root - height); 197 return (height); 198} 199 200 201/* 202 * Set the root node and height for a radix tree. 203 */ 204static inline void 205vm_radix_setroot(struct vm_radix *rtree, struct vm_radix_node *rnode, 206 int height) 207{ 208 uintptr_t root; 209 210 root = (uintptr_t)rnode | height; 211 rtree->rt_root = root; 212} 213 214static inline void * 215vm_radix_match(void *child, int color) 216{ 217 uintptr_t c; 218 219 c = (uintptr_t)child; 220 221 if ((c & color) == 0) 222 return (NULL); 223 return ((void *)(c & ~VM_RADIX_FLAGS)); 224} 225 226static void 227vm_radix_reclaim_allnodes_internal(struct vm_radix_node *rnode, int level) 228{ 229 int slot; 230 231 MPASS(rnode != NULL && level >= 0); 232 233 /* 234 * Level 0 just contains pages as children, thus make it a special 235 * case, free the node and return. 236 */ 237 if (level == 0) { 238 CTR2(KTR_VM, "reclaiming: node %p, level %d", rnode, level); 239 rnode->rn_count = 0; 240 vm_radix_node_put(rnode); 241 return; 242 } 243 for (slot = 0; slot < VM_RADIX_COUNT && rnode->rn_count != 0; slot++) { 244 if (rnode->rn_child[slot] == NULL) 245 continue; 246 CTR3(KTR_VM, 247 "reclaiming: node %p, level %d recursing in slot %d", 248 rnode, level, slot); 249 vm_radix_reclaim_allnodes_internal(rnode->rn_child[slot], 250 level - 1); 251 rnode->rn_count--; 252 } 253 MPASS(rnode->rn_count == 0); 254 CTR2(KTR_VM, "reclaiming: node %p, level %d", rnode, level); 255 vm_radix_node_put(rnode); 256} 257 258/* 259 * Inserts the key-value pair in to the radix tree. Returns errno. 260 * Panics if the key already exists. 261 */ 262int 263vm_radix_insert(struct vm_radix *rtree, vm_pindex_t index, void *val) 264{ 265 struct vm_radix_node *rnode; 266 struct vm_radix_node *root; 267 int level; 268 int slot; 269 270 CTR3(KTR_VM, 271 "insert: tree %p, index %p, val %p", rtree, (void *)index, val); 272 if (index == -1) 273 panic("vm_radix_insert: -1 is not a valid index.\n"); 274 level = vm_radix_height(rtree, &root); 275 /* 276 * Increase the height by adding nodes at the root until 277 * there is sufficient space. 278 */ 279 while (level == 0 || index > VM_RADIX_MAX(level)) { 280 CTR3(KTR_VM, "insert: expanding %jd > %jd height %d", 281 index, VM_RADIX_MAX(level), level); 282 level++; 283 KASSERT(level <= VM_RADIX_LIMIT, 284 ("vm_radix_insert: Tree %p height %d too tall", 285 rtree, level)); 286 /* 287 * Only allocate tree nodes if they are needed. 288 */ 289 if (root == NULL || root->rn_count != 0) { 290 rnode = vm_radix_node_get(); 291 if (rnode == NULL) { 292 CTR4(KTR_VM, 293 "insert: tree %p, root %p, index: %d, level: %d ENOMEM", 294 rtree, root, index, level); 295 return (ENOMEM); 296 } 297 /* 298 * Store the new pointer with a memory barrier so 299 * that it is visible before the new root. 300 */ 301 if (root) { 302 atomic_store_rel_ptr((volatile uintptr_t *) 303 &rnode->rn_child[0], (uintptr_t)root); 304 rnode->rn_count = 1; 305 } 306 root = rnode; 307 } 308 vm_radix_setroot(rtree, root, level); 309 } 310 311 /* Now that the tree is tall enough, fill in the path to the index. */ 312 rnode = root; 313 for (level = level - 1; level > 0; level--) { 314 slot = vm_radix_slot(index, level); 315 /* Add the required intermidiate nodes. */ 316 if (rnode->rn_child[slot] == NULL) { 317 rnode->rn_child[slot] = vm_radix_node_get(); 318 if (rnode->rn_child[slot] == NULL) { 319 CTR6(KTR_VM, 320"insert: tree %p, index %jd, level %d, slot %d, rnode %p, child %p ENOMEM", 321 rtree, index, level, slot, rnode, 322 (rnode != NULL) ? rnode->rn_child[slot] : 323 NULL); 324 return (ENOMEM); 325 } 326 rnode->rn_count++; 327 } 328 CTR6(KTR_VM, 329 "insert: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 330 rtree, (void *)index, level, slot, rnode, 331 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 332 rnode = rnode->rn_child[slot]; 333 } 334 335 slot = vm_radix_slot(index, 0); 336 CTR6(KTR_VM, 337 "insert: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 338 rtree, (void *)index, level, slot, rnode, 339 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 340 KASSERT(rnode->rn_child[slot] == NULL, 341 ("vm_radix_insert: Duplicate value %p at index: %lu\n", 342 rnode->rn_child[slot], (u_long)index)); 343 val = (void *)((uintptr_t)val | VM_RADIX_BLACK); 344 rnode->rn_child[slot] = val; 345 atomic_add_int((volatile int *)&rnode->rn_count, 1); 346 347 return 0; 348} 349 350/* 351 * Returns the value stored at the index. If the index is not present 352 * NULL is returned. 353 */ 354void * 355vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index, int color) 356{ 357 struct vm_radix_node *rnode; 358 int slot; 359 int level; 360 361 level = vm_radix_height(rtree, &rnode); 362 if (index > VM_RADIX_MAX(level)) 363 return NULL; 364 level--; 365 while (rnode) { 366 slot = vm_radix_slot(index, level); 367 CTR6(KTR_VM, 368 "lookup: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 369 rtree, (void *)index, level, slot, rnode, 370 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 371 if (level == 0) 372 return vm_radix_match(rnode->rn_child[slot], color); 373 rnode = rnode->rn_child[slot]; 374 level--; 375 } 376 CTR2(KTR_VM, "lookup: tree %p, index %p failed", rtree, (void *)index); 377 378 return NULL; 379} 380 381void * 382vm_radix_color(struct vm_radix *rtree, vm_pindex_t index, int color) 383{ 384 struct vm_radix_node *rnode; 385 uintptr_t child; 386 int slot; 387 int level; 388 389 level = vm_radix_height(rtree, &rnode); 390 if (index > VM_RADIX_MAX(level)) 391 return NULL; 392 level--; 393 while (rnode) { 394 slot = vm_radix_slot(index, level); 395 CTR6(KTR_VM, 396 "color: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 397 rtree, (void *)index, level, slot, rnode, 398 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 399 if (level == 0) 400 break; 401 rnode = rnode->rn_child[slot]; 402 level--; 403 } 404 if (rnode == NULL || rnode->rn_child[slot] == NULL) 405 return (NULL); 406 child = (uintptr_t)rnode->rn_child[slot]; 407 child &= ~VM_RADIX_FLAGS; 408 rnode->rn_child[slot] = (void *)(child | color); 409 410 return (void *)child; 411} 412 413/* 414 * Find the first leaf with a valid node between *startp and end. Return 415 * the index of the first valid item in the leaf in *startp. 416 */ 417static struct vm_radix_node * 418vm_radix_leaf(struct vm_radix *rtree, vm_pindex_t *startp, vm_pindex_t end) 419{ 420 struct vm_radix_node *rnode; 421 vm_pindex_t start; 422 vm_pindex_t inc; 423 int slot; 424 int level; 425 426 start = *startp; 427restart: 428 level = vm_radix_height(rtree, &rnode); 429 if (start > VM_RADIX_MAX(level) || (end && start >= end)) { 430 rnode = NULL; 431 goto out; 432 } 433 /* 434 * Search the tree from the top for any leaf node holding an index 435 * between start and end. 436 */ 437 for (level--; level; level--) { 438 slot = vm_radix_slot(start, level); 439 CTR6(KTR_VM, 440 "leaf: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 441 rtree, (void *)start, level, slot, rnode, 442 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 443 if (rnode->rn_child[slot] != NULL) { 444 rnode = rnode->rn_child[slot]; 445 continue; 446 } 447 /* 448 * Calculate how much to increment our index by 449 * based on the tree level. We must truncate the 450 * lower bits to start from the begnning of the 451 * next leaf. 452 */ 453 inc = 1LL << (level * VM_RADIX_WIDTH); 454 start &= ~VM_RADIX_MAX(level); 455 start += inc; 456 slot++; 457 CTR5(KTR_VM, 458 "leaf: start %p end %p inc %d mask 0x%lX slot %d", 459 (void *)start, (void *)end, inc, 460 ~VM_RADIX_MAX(level), slot); 461 for (; slot < VM_RADIX_COUNT; slot++, start += inc) { 462 if (end != 0 && start >= end) { 463 rnode = NULL; 464 goto out; 465 } 466 if (rnode->rn_child[slot]) { 467 rnode = rnode->rn_child[slot]; 468 break; 469 } 470 } 471 if (slot == VM_RADIX_COUNT) 472 goto restart; 473 } 474 475out: 476 *startp = start; 477 return (rnode); 478} 479 480 481 482/* 483 * Looks up as many as cnt values between start and end, and stores 484 * them in the caller allocated array out. The next index can be used 485 * to restart the scan. This optimizes forward scans in the tree. 486 */ 487int 488vm_radix_lookupn(struct vm_radix *rtree, vm_pindex_t start, 489 vm_pindex_t end, int color, void **out, int cnt, vm_pindex_t *next) 490{ 491 struct vm_radix_node *rnode; 492 void *val; 493 int slot; 494 int outidx; 495 496 CTR3(KTR_VM, "lookupn: tree %p, start %p, end %p", 497 rtree, (void *)start, (void *)end); 498 if (rtree->rt_root == 0) 499 return (0); 500 outidx = 0; 501 while ((rnode = vm_radix_leaf(rtree, &start, end)) != NULL) { 502 slot = vm_radix_slot(start, 0); 503 for (; slot < VM_RADIX_COUNT; slot++, start++) { 504 if (end != 0 && start >= end) 505 goto out; 506 val = vm_radix_match(rnode->rn_child[slot], color); 507 if (val == NULL) 508 continue; 509 CTR4(KTR_VM, 510 "lookupn: tree %p index %p slot %d found child %p", 511 rtree, (void *)start, slot, val); 512 out[outidx] = val; 513 if (++outidx == cnt) 514 goto out; 515 } 516 if (end != 0 && start >= end) 517 break; 518 } 519out: 520 *next = start; 521 return (outidx); 522} 523 524void 525vm_radix_foreach(struct vm_radix *rtree, vm_pindex_t start, vm_pindex_t end, 526 int color, void (*iter)(void *)) 527{ 528 struct vm_radix_node *rnode; 529 void *val; 530 int slot; 531 532 if (rtree->rt_root == 0) 533 return; 534 while ((rnode = vm_radix_leaf(rtree, &start, end)) != NULL) { 535 slot = vm_radix_slot(start, 0); 536 for (; slot < VM_RADIX_COUNT; slot++, start++) { 537 if (end != 0 && start >= end) 538 return; 539 val = vm_radix_match(rnode->rn_child[slot], color); 540 if (val) 541 iter(val); 542 } 543 if (end != 0 && start >= end) 544 return; 545 } 546} 547 548 549/* 550 * Look up any entry at a position less than or equal to index. 551 */ 552void * 553vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index, int color) 554{ 555 struct vm_radix_node *rnode; 556 struct vm_radix_node *child; 557 vm_pindex_t max; 558 vm_pindex_t inc; 559 void *val; 560 int slot; 561 int level; 562 563 CTR2(KTR_VM, 564 "lookup_le: tree %p, index %p", rtree, (void *)index); 565restart: 566 level = vm_radix_height(rtree, &rnode); 567 if (rnode == NULL) 568 return (NULL); 569 max = VM_RADIX_MAX(level); 570 if (index > max || index == 0) 571 index = max; 572 /* 573 * Search the tree from the top for any leaf node holding an index 574 * lower than 'index'. 575 */ 576 level--; 577 while (rnode) { 578 slot = vm_radix_slot(index, level); 579 CTR6(KTR_VM, 580 "lookup_le: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 581 rtree, (void *)index, level, slot, rnode, 582 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 583 if (level == 0) 584 break; 585 /* 586 * If we don't have an exact match we must start our search 587 * from the next leaf and adjust our index appropriately. 588 */ 589 if ((child = rnode->rn_child[slot]) == NULL) { 590 /* 591 * Calculate how much to decrement our index by 592 * based on the tree level. We must set the 593 * lower bits to start from the end of the next 594 * leaf. 595 */ 596 inc = 1LL << (level * VM_RADIX_WIDTH); 597 index |= VM_RADIX_MAX(level); 598 index -= inc; 599 slot--; 600 CTR4(KTR_VM, 601 "lookup_le: start %p inc %ld mask 0x%lX slot %d", 602 (void *)index, inc, VM_RADIX_MAX(level), slot); 603 for (; slot >= 0; slot--, index -= inc) { 604 child = rnode->rn_child[slot]; 605 if (child) 606 break; 607 } 608 } 609 rnode = child; 610 level--; 611 } 612 if (rnode) { 613 for (; slot >= 0; slot--, index--) { 614 val = vm_radix_match(rnode->rn_child[slot], color); 615 if (val) 616 return (val); 617 } 618 } 619 if (index != -1) 620 goto restart; 621 return (NULL); 622} 623 624/* 625 * Remove the specified index from the tree. If possible the height of the 626 * tree is adjusted after deletion. The value stored at index is returned 627 * panics if the key is not present. 628 */ 629void * 630vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index, int color) 631{ 632 struct vm_radix_node *stack[VM_RADIX_LIMIT]; 633 struct vm_radix_node *rnode, *root; 634 void *val; 635 int level; 636 int slot; 637 638 level = vm_radix_height(rtree, &root); 639 KASSERT(index <= VM_RADIX_MAX(level), 640 ("vm_radix_remove: %p index %jd out of range %jd.", 641 rtree, index, VM_RADIX_MAX(level))); 642 rnode = root; 643 val = NULL; 644 level--; 645 /* 646 * Find the node and record the path in stack. 647 */ 648 while (level && rnode) { 649 stack[level] = rnode; 650 slot = vm_radix_slot(index, level); 651 CTR6(KTR_VM, 652 "remove: tree %p, index %p, level %d, slot %d, rnode %p, child %p", 653 rtree, (void *)index, level, slot, rnode, 654 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 655 rnode = rnode->rn_child[slot]; 656 level--; 657 } 658 KASSERT(rnode != NULL, 659 ("vm_radix_remove: index %jd not present in the tree.\n", index)); 660 slot = vm_radix_slot(index, 0); 661 val = vm_radix_match(rnode->rn_child[slot], color); 662 KASSERT(val != NULL, 663 ("vm_radix_remove: index %jd not present in the tree.\n", index)); 664 665 for (;;) { 666 CTR6(KTR_VM, 667"remove: resetting tree %p, index %p, level %d, slot %d, rnode %p, child %p", 668 rtree, (void *)index, level, slot, rnode, 669 (rnode != NULL) ? rnode->rn_child[slot] : NULL); 670 CTR3(KTR_VM, "remove: rnode %p, count %p, color %d", 671 rnode, (rnode != NULL) ? rnode->rn_count : NULL, color); 672 rnode->rn_child[slot] = NULL; 673 /* 674 * Use atomics for the last level since red and black 675 * will both adjust it. 676 */ 677 if (level == 0) 678 atomic_add_int((volatile int *)&rnode->rn_count, -1); 679 else 680 rnode->rn_count--; 681 /* 682 * Only allow black removes to prune the tree. 683 */ 684 if ((color & VM_RADIX_BLACK) == 0 || rnode->rn_count > 0) 685 break; 686 vm_radix_node_put(rnode); 687 if (rnode == root) { 688 vm_radix_setroot(rtree, NULL, 0); 689 break; 690 } 691 rnode = stack[++level]; 692 slot = vm_radix_slot(index, level); 693 694 } 695 return (val); 696} 697 698/* 699 * Remove and free all the nodes from the radix tree. 700 * This function is recrusive but there is a tight control on it as the 701 * maximum depth of the tree is fixed. 702 */ 703void 704vm_radix_reclaim_allnodes(struct vm_radix *rtree) 705{ 706 struct vm_radix_node *root; 707 int level; 708 709 if (rtree->rt_root == 0) 710 return; 711 level = vm_radix_height(rtree, &root); 712 vm_radix_reclaim_allnodes_internal(root, level - 1); 713 rtree->rt_root = 0; 714} 715 716/* 717 * Attempts to reduce the height of the tree. 718 */ 719void 720vm_radix_shrink(struct vm_radix *rtree) 721{ 722 struct vm_radix_node *tmp, *root; 723 int level; 724 725 if (rtree->rt_root == 0) 726 return; 727 level = vm_radix_height(rtree, &root); 728 729 /* Adjust the height of the tree. */ 730 while (root->rn_count == 1 && root->rn_child[0] != NULL) { 731 tmp = root; 732 root->rn_count--; 733 root = root->rn_child[0]; 734 level--; 735 vm_radix_node_put(tmp); 736 } 737 /* Finally see if we have an empty tree. */ 738 if (root->rn_count == 0) { 739 vm_radix_node_put(root); 740 root = NULL; 741 level--; 742 } 743 vm_radix_setroot(rtree, root, level); 744} 745