lib/radix-tree.c

   1 /*
   2  * Copyright (C) 2001 Momchil Velikov
   3  * Portions Copyright (C) 2001 Christoph Hellwig
   4  * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2, or (at
   9  * your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/errno.h>
  22 #include <linux/init.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/radix-tree.h>
  26 #include <linux/percpu.h>
  27 #include <linux/slab.h>
  28 #include <linux/notifier.h>
  29 #include <linux/cpu.h>
  30 #include <linux/gfp.h>
  31 #include <linux/string.h>
  32 #include <linux/bitops.h>
  33
  34
  35 #ifdef __KERNEL__
  36 #define RADIX_TREE_MAP_SHIFT    6
  37 #else
  38 #define RADIX_TREE_MAP_SHIFT    3       /* For more stressful testing */
  39 #endif
  40 #define RADIX_TREE_TAGS         2
  41
  42 #define RADIX_TREE_MAP_SIZE     (1UL << RADIX_TREE_MAP_SHIFT)
  43 #define RADIX_TREE_MAP_MASK     (RADIX_TREE_MAP_SIZE-1)
  44
  45 #define RADIX_TREE_TAG_LONGS    \
  46         ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
  47
  48 struct radix_tree_node {
  49         unsigned int    count;
  50         void            *slots[RADIX_TREE_MAP_SIZE];
  51         unsigned long   tags[RADIX_TREE_TAGS][RADIX_TREE_TAG_LONGS];
  52 };
  53
  54 struct radix_tree_path {
  55         struct radix_tree_node *node;
  56         int offset;
  57 };
  58
  59 #define RADIX_TREE_INDEX_BITS  (8 /* CHAR_BIT */ * sizeof(unsigned long))
  60 #define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
  61
  62 static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
  63
  64 /*
  65  * Radix tree node cache.
  66  */
  67 static kmem_cache_t *radix_tree_node_cachep;
  68
  69 /*
  70  * Per-cpu pool of preloaded nodes
  71  */
  72 struct radix_tree_preload {
  73         int nr;
  74         struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
  75 };
  76 DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
  77
  78 /*
  79  * This assumes that the caller has performed appropriate preallocation, and
  80  * that the caller has pinned this thread of control to the current CPU.
  81  */
  82 static struct radix_tree_node *
  83 radix_tree_node_alloc(struct radix_tree_root *root)
  84 {
  85         struct radix_tree_node *ret;
  86
  87         ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask);
  88         if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) {
  89                 struct radix_tree_preload *rtp;
  90
  91                 rtp = &__get_cpu_var(radix_tree_preloads);
  92                 if (rtp->nr) {
  93                         ret = rtp->nodes[rtp->nr - 1];
  94                         rtp->nodes[rtp->nr - 1] = NULL;
  95                         rtp->nr--;
  96                 }
  97         }
  98         return ret;
  99 }
 100
 101 static inline void
 102 radix_tree_node_free(struct radix_tree_node *node)
 103 {
 104         kmem_cache_free(radix_tree_node_cachep, node);
 105 }
 106
 107 /*
 108  * Load up this CPU's radix_tree_node buffer with sufficient objects to
 109  * ensure that the addition of a single element in the tree cannot fail.  On
 110  * success, return zero, with preemption disabled.  On error, return -ENOMEM
 111  * with preemption not disabled.
 112  */
 113 int radix_tree_preload(int gfp_mask)
 114 {
 115         struct radix_tree_preload *rtp;
 116         struct radix_tree_node *node;
 117         int ret = -ENOMEM;
 118
 119         preempt_disable();
 120         rtp = &__get_cpu_var(radix_tree_preloads);
 121         while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
 122                 preempt_enable();
 123                 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
 124                 if (node == NULL)
 125                         goto out;
 126                 preempt_disable();
 127                 rtp = &__get_cpu_var(radix_tree_preloads);
 128                 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
 129                         rtp->nodes[rtp->nr++] = node;
 130                 else
 131                         kmem_cache_free(radix_tree_node_cachep, node);
 132         }
 133         ret = 0;
 134 out:
 135         return ret;
 136 }
 137
 138 static inline void tag_set(struct radix_tree_node *node, int tag, int offset)
 139 {
 140         if (!test_bit(offset, &node->tags[tag][0]))
 141                 __set_bit(offset, &node->tags[tag][0]);
 142 }
 143
 144 static inline void tag_clear(struct radix_tree_node *node, int tag, int offset)
 145 {
 146         __clear_bit(offset, &node->tags[tag][0]);
 147 }
 148
 149 static inline int tag_get(struct radix_tree_node *node, int tag, int offset)
 150 {
 151         return test_bit(offset, &node->tags[tag][0]);
 152 }
 153
 154 /*
 155  *      Return the maximum key which can be store into a
 156  *      radix tree with height HEIGHT.
 157  */
 158 static inline unsigned long radix_tree_maxindex(unsigned int height)
 159 {
 160         return height_to_maxindex[height];
 161 }
 162
 163 /*
 164  *      Extend a radix tree so it can store key @index.
 165  */
 166 static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
 167 {
 168         struct radix_tree_node *node;
 169         unsigned int height;
 170         char tags[RADIX_TREE_TAGS];
 171         int tag;
 172
 173         /* Figure out what the height should be.  */
 174         height = root->height + 1;
 175         while (index > radix_tree_maxindex(height))
 176                 height++;
 177
 178         if (root->rnode == NULL) {
 179                 root->height = height;
 180                 goto out;
 181         }
 182
 183         /*
 184          * Prepare the tag status of the top-level node for propagation
 185          * into the newly-pushed top-level node(s)
 186          */
 187         for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
 188                 int idx;
 189
 190                 tags[tag] = 0;
 191                 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 192                         if (root->rnode->tags[tag][idx]) {
 193                                 tags[tag] = 1;
 194                                 break;
 195                         }
 196                 }
 197         }
 198
 199         do {
 200                 if (!(node = radix_tree_node_alloc(root)))
 201                         return -ENOMEM;
 202
 203                 /* Increase the height.  */
 204                 node->slots[0] = root->rnode;
 205
 206                 /* Propagate the aggregated tag info into the new root */
 207                 for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
 208                         if (tags[tag])
 209                                 tag_set(node, tag, 0);
 210                 }
 211
 212                 node->count = 1;
 213                 root->rnode = node;
 214                 root->height++;
 215         } while (height > root->height);
 216 out:
 217         return 0;
 218 }
 219
 220 /**
 221  *      radix_tree_insert    -    insert into a radix tree
 222  *      @root:          radix tree root
 223  *      @index:         index key
 224  *      @item:          item to insert
 225  *
 226  *      Insert an item into the radix tree at position @index.
 227  */
 228 int radix_tree_insert(struct radix_tree_root *root,
 229                         unsigned long index, void *item)
 230 {
 231         struct radix_tree_node *node = NULL, *slot;
 232         unsigned int height, shift;
 233         int offset;
 234         int error;
 235
 236         /* Make sure the tree is high enough.  */
 237         if ((!index && !root->rnode) ||
 238                         index > radix_tree_maxindex(root->height)) {
 239                 error = radix_tree_extend(root, index);
 240                 if (error)
 241                         return error;
 242         }
 243
 244         slot = root->rnode;
 245         height = root->height;
 246         shift = (height-1) * RADIX_TREE_MAP_SHIFT;
 247
 248         offset = 0;                     /* uninitialised var warning */
 249         while (height > 0) {
 250                 if (slot == NULL) {
 251                         /* Have to add a child node.  */
 252                         if (!(slot = radix_tree_node_alloc(root)))
 253                                 return -ENOMEM;
 254                         if (node) {
 255                                 node->slots[offset] = slot;
 256                                 node->count++;
 257                         } else
 258                                 root->rnode = slot;
 259                 }
 260
 261                 /* Go a level down */
 262                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 263                 node = slot;
 264                 slot = node->slots[offset];
 265                 shift -= RADIX_TREE_MAP_SHIFT;
 266                 height--;
 267         }
 268
 269         if (slot != NULL)
 270                 return -EEXIST;
 271
 272         if (node) {
 273                 node->count++;
 274                 node->slots[offset] = item;
 275                 BUG_ON(tag_get(node, 0, offset));
 276                 BUG_ON(tag_get(node, 1, offset));
 277         } else
 278                 root->rnode = item;
 279
 280         return 0;
 281 }
 282 EXPORT_SYMBOL(radix_tree_insert);
 283
 284 /**
 285  *      radix_tree_lookup    -    perform lookup operation on a radix tree
 286  *      @root:          radix tree root
 287  *      @index:         index key
 288  *
 289  *      Lookup the item at the position @index in the radix tree @root.
 290  */
 291 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
 292 {
 293         unsigned int height, shift;
 294         struct radix_tree_node *slot;
 295
 296         height = root->height;
 297         if (index > radix_tree_maxindex(height))
 298                 return NULL;
 299
 300         shift = (height-1) * RADIX_TREE_MAP_SHIFT;
 301         slot = root->rnode;
 302
 303         while (height > 0) {
 304                 if (slot == NULL)
 305                         return NULL;
 306
 307                 slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];
 308                 shift -= RADIX_TREE_MAP_SHIFT;
 309                 height--;
 310         }
 311
 312         return slot;
 313 }
 314 EXPORT_SYMBOL(radix_tree_lookup);
 315
 316 /**
 317  *      radix_tree_tag_set - set a tag on a radix tree node
 318  *      @root:          radix tree root
 319  *      @index:         index key
 320  *      @tag:           tag index
 321  *
 322  *      Set the search tag corresponging to @index in the radix tree.  From
 323  *      the root all the way down to the leaf node.
 324  *
 325  *      Returns the address of the tagged item.   Setting a tag on a not-present
 326  *      item is a bug.
 327  */
 328 void *radix_tree_tag_set(struct radix_tree_root *root,
 329                         unsigned long index, int tag)
 330 {
 331         unsigned int height, shift;
 332         struct radix_tree_node *slot;
 333
 334         height = root->height;
 335         if (index > radix_tree_maxindex(height))
 336                 return NULL;
 337
 338         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 339         slot = root->rnode;
 340
 341         while (height > 0) {
 342                 int offset;
 343
 344                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 345                 tag_set(slot, tag, offset);
 346                 slot = slot->slots[offset];
 347                 BUG_ON(slot == NULL);
 348                 shift -= RADIX_TREE_MAP_SHIFT;
 349                 height--;
 350         }
 351
 352         return slot;
 353 }
 354 EXPORT_SYMBOL(radix_tree_tag_set);
 355
 356 /**
 357  *      radix_tree_tag_clear - clear a tag on a radix tree node
 358  *      @root:          radix tree root
 359  *      @index:         index key
 360  *      @tag:           tag index
 361  *
 362  *      Clear the search tag corresponging to @index in the radix tree.  If
 363  *      this causes the leaf node to have no tags set then clear the tag in the
 364  *      next-to-leaf node, etc.
 365  *
 366  *      Returns the address of the tagged item on success, else NULL.  ie:
 367  *      has the same return value and semantics as radix_tree_lookup().
 368  */
 369 void *radix_tree_tag_clear(struct radix_tree_root *root,
 370                         unsigned long index, int tag)
 371 {
 372         struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
 373         struct radix_tree_node *slot;
 374         unsigned int height, shift;
 375         void *ret = NULL;
 376
 377         height = root->height;
 378         if (index > radix_tree_maxindex(height))
 379                 goto out;
 380
 381         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 382         pathp->node = NULL;
 383         slot = root->rnode;
 384
 385         while (height > 0) {
 386                 int offset;
 387
 388                 if (slot == NULL)
 389                         goto out;
 390
 391                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 392                 pathp[1].offset = offset;
 393                 pathp[1].node = slot;
 394                 slot = slot->slots[offset];
 395                 pathp++;
 396                 shift -= RADIX_TREE_MAP_SHIFT;
 397                 height--;
 398         }
 399
 400         ret = slot;
 401         if (ret == NULL)
 402                 goto out;
 403
 404         do {
 405                 int idx;
 406
 407                 tag_clear(pathp->node, tag, pathp->offset);
 408                 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 409                         if (pathp->node->tags[tag][idx])
 410                                 goto out;
 411                 }
 412                 pathp--;
 413         } while (pathp->node);
 414 out:
 415         return ret;
 416 }
 417 EXPORT_SYMBOL(radix_tree_tag_clear);
 418
 419 #ifndef __KERNEL__      /* Only the test harness uses this at present */
 420 /**
 421  *      radix_tree_tag_get - get a tag on a radix tree node
 422  *      @root:          radix tree root
 423  *      @index:         index key
 424  *      @tag:           tag index
 425  *
 426  *      Return the search tag corresponging to @index in the radix tree.
 427  *
 428  *      Returns zero if the tag is unset, or if there is no corresponding item
 429  *      in the tree.
 430  */
 431 int radix_tree_tag_get(struct radix_tree_root *root,
 432                         unsigned long index, int tag)
 433 {
 434         unsigned int height, shift;
 435         struct radix_tree_node *slot;
 436         int saw_unset_tag = 0;
 437
 438         height = root->height;
 439         if (index > radix_tree_maxindex(height))
 440                 return 0;
 441
 442         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 443         slot = root->rnode;
 444
 445         for ( ; ; ) {
 446                 int offset;
 447
 448                 if (slot == NULL)
 449                         return 0;
 450
 451                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 452
 453                 /*
 454                  * This is just a debug check.  Later, we can bale as soon as
 455                  * we see an unset tag.
 456                  */
 457                 if (!tag_get(slot, tag, offset))
 458                         saw_unset_tag = 1;
 459                 if (height == 1) {
 460                         int ret = tag_get(slot, tag, offset);
 461
 462                         BUG_ON(ret && saw_unset_tag);
 463                         return ret;
 464                 }
 465                 slot = slot->slots[offset];
 466                 shift -= RADIX_TREE_MAP_SHIFT;
 467                 height--;
 468         }
 469 }
 470 EXPORT_SYMBOL(radix_tree_tag_get);
 471 #endif
 472
 473 static unsigned int
 474 __lookup(struct radix_tree_root *root, void **results, unsigned long index,
 475         unsigned int max_items, unsigned long *next_index)
 476 {
 477         unsigned int nr_found = 0;
 478         unsigned int shift, height;
 479         struct radix_tree_node *slot;
 480         unsigned long i;
 481
 482         height = root->height;
 483         if (height == 0)
 484                 goto out;
 485
 486         shift = (height-1) * RADIX_TREE_MAP_SHIFT;
 487         slot = root->rnode;
 488
 489         for ( ; height > 1; height--) {
 490
 491                 for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
 492                                 i < RADIX_TREE_MAP_SIZE; i++) {
 493                         if (slot->slots[i] != NULL)
 494                                 break;
 495                         index &= ~((1UL << shift) - 1);
 496                         index += 1UL << shift;
 497                         if (index == 0)
 498                                 goto out;       /* 32-bit wraparound */
 499                 }
 500                 if (i == RADIX_TREE_MAP_SIZE)
 501                         goto out;
 502
 503                 shift -= RADIX_TREE_MAP_SHIFT;
 504                 slot = slot->slots[i];
 505         }
 506
 507         /* Bottom level: grab some items */
 508         for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
 509                 index++;
 510                 if (slot->slots[i]) {
 511                         results[nr_found++] = slot->slots[i];
 512                         if (nr_found == max_items)
 513                                 goto out;
 514                 }
 515         }
 516 out:
 517         *next_index = index;
 518         return nr_found;
 519 }
 520
 521 /**
 522  *      radix_tree_gang_lookup - perform multiple lookup on a radix tree
 523  *      @root:          radix tree root
 524  *      @results:       where the results of the lookup are placed
 525  *      @first_index:   start the lookup from this key
 526  *      @max_items:     place up to this many items at *results
 527  *
 528  *      Performs an index-ascending scan of the tree for present items.  Places
 529  *      them at *@results and returns the number of items which were placed at
 530  *      *@results.
 531  *
 532  *      The implementation is naive.
 533  */
 534 unsigned int
 535 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 536                         unsigned long first_index, unsigned int max_items)
 537 {
 538         const unsigned long max_index = radix_tree_maxindex(root->height);
 539         unsigned long cur_index = first_index;
 540         unsigned int ret = 0;
 541
 542         while (ret < max_items) {
 543                 unsigned int nr_found;
 544                 unsigned long next_index;       /* Index of next search */
 545
 546                 if (cur_index > max_index)
 547                         break;
 548                 nr_found = __lookup(root, results + ret, cur_index,
 549                                         max_items - ret, &next_index);
 550                 ret += nr_found;
 551                 if (next_index == 0)
 552                         break;
 553                 cur_index = next_index;
 554         }
 555         return ret;
 556 }
 557 EXPORT_SYMBOL(radix_tree_gang_lookup);
 558
 559 /*
 560  * FIXME: the two tag_get()s here should use find_next_bit() instead of
 561  * open-coding the search.
 562  */
 563 static unsigned int
 564 __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
 565         unsigned int max_items, unsigned long *next_index, int tag)
 566 {
 567         unsigned int nr_found = 0;
 568         unsigned int shift;
 569         unsigned int height = root->height;
 570         struct radix_tree_node *slot;
 571
 572         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 573         slot = root->rnode;
 574
 575         while (height > 0) {
 576                 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
 577
 578                 for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
 579                         if (tag_get(slot, tag, i)) {
 580                                 BUG_ON(slot->slots[i] == NULL);
 581                                 break;
 582                         }
 583                         index &= ~((1UL << shift) - 1);
 584                         index += 1UL << shift;
 585                         if (index == 0)
 586                                 goto out;       /* 32-bit wraparound */
 587                 }
 588                 if (i == RADIX_TREE_MAP_SIZE)
 589                         goto out;
 590                 height--;
 591                 if (height == 0) {      /* Bottom level: grab some items */
 592                         unsigned long j = index & RADIX_TREE_MAP_MASK;
 593
 594                         for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
 595                                 index++;
 596                                 if (tag_get(slot, tag, j)) {
 597                                         BUG_ON(slot->slots[j] == NULL);
 598                                         results[nr_found++] = slot->slots[j];
 599                                         if (nr_found == max_items)
 600                                                 goto out;
 601                                 }
 602                         }
 603                 }
 604                 shift -= RADIX_TREE_MAP_SHIFT;
 605                 slot = slot->slots[i];
 606         }
 607 out:
 608         *next_index = index;
 609         return nr_found;
 610 }
 611
 612 /**
 613  *      radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
 614  *                                   based on a tag
 615  *      @root:          radix tree root
 616  *      @results:       where the results of the lookup are placed
 617  *      @first_index:   start the lookup from this key
 618  *      @max_items:     place up to this many items at *results
 619  *      @tag:           the tag index
 620  *
 621  *      Performs an index-ascending scan of the tree for present items which
 622  *      have the tag indexed by @tag set.  Places the items at *@results and
 623  *      returns the number of items which were placed at *@results.
 624  */
 625 unsigned int
 626 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
 627                 unsigned long first_index, unsigned int max_items, int tag)
 628 {
 629         const unsigned long max_index = radix_tree_maxindex(root->height);
 630         unsigned long cur_index = first_index;
 631         unsigned int ret = 0;
 632
 633         while (ret < max_items) {
 634                 unsigned int nr_found;
 635                 unsigned long next_index;       /* Index of next search */
 636
 637                 if (cur_index > max_index)
 638                         break;
 639                 nr_found = __lookup_tag(root, results + ret, cur_index,
 640                                         max_items - ret, &next_index, tag);
 641                 ret += nr_found;
 642                 if (next_index == 0)
 643                         break;
 644                 cur_index = next_index;
 645         }
 646         return ret;
 647 }
 648 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
 649
 650 /**
 651  *      radix_tree_delete    -    delete an item from a radix tree
 652  *      @root:          radix tree root
 653  *      @index:         index key
 654  *
 655  *      Remove the item at @index from the radix tree rooted at @root.
 656  *
 657  *      Returns the address of the deleted item, or NULL if it was not present.
 658  */
 659 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
 660 {
 661         struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
 662         struct radix_tree_path *orig_pathp;
 663         struct radix_tree_node *slot;
 664         unsigned int height, shift;
 665         void *ret = NULL;
 666         char tags[RADIX_TREE_TAGS];
 667         int nr_cleared_tags;
 668
 669         height = root->height;
 670         if (index > radix_tree_maxindex(height))
 671                 goto out;
 672
 673         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 674         pathp->node = NULL;
 675         slot = root->rnode;
 676
 677         for ( ; height > 0; height--) {
 678                 int offset;
 679
 680                 if (slot == NULL)
 681                         goto out;
 682
 683                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 684                 pathp[1].offset = offset;
 685                 pathp[1].node = slot;
 686                 slot = slot->slots[offset];
 687                 pathp++;
 688                 shift -= RADIX_TREE_MAP_SHIFT;
 689         }
 690
 691         ret = slot;
 692         if (ret == NULL)
 693                 goto out;
 694
 695         orig_pathp = pathp;
 696
 697         /*
 698          * Clear all tags associated with the just-deleted item
 699          */
 700         memset(tags, 0, sizeof(tags));
 701         do {
 702                 int tag;
 703
 704                 nr_cleared_tags = RADIX_TREE_TAGS;
 705                 for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
 706                         int idx;
 707
 708                         if (tags[tag])
 709                                 continue;
 710
 711                         tag_clear(pathp->node, tag, pathp->offset);
 712
 713                         for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 714                                 if (pathp->node->tags[tag][idx]) {
 715                                         tags[tag] = 1;
 716                                         nr_cleared_tags--;
 717                                         break;
 718                                 }
 719                         }
 720                 }
 721                 pathp--;
 722         } while (pathp->node && nr_cleared_tags);
 723
 724         /* Now free the nodes we do not need anymore */
 725         for (pathp = orig_pathp; pathp->node; pathp--) {
 726                 pathp->node->slots[pathp->offset] = NULL;
 727                 if (--pathp->node->count)
 728                         goto out;
 729
 730                 /* Node with zero slots in use so free it */
 731                 radix_tree_node_free(pathp->node);
 732         }
 733         root->rnode = NULL;
 734         root->height = 0;
 735 out:
 736         return ret;
 737 }
 738 EXPORT_SYMBOL(radix_tree_delete);
 739
 740 /**
 741  *      radix_tree_tagged - test whether any items in the tree are tagged
 742  *      @root:          radix tree root
 743  *      @tag:           tag to test
 744  */
 745 int radix_tree_tagged(struct radix_tree_root *root, int tag)
 746 {
 747         int idx;
 748
 749         if (!root->rnode)
 750                 return 0;
 751         for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 752                 if (root->rnode->tags[tag][idx])
 753                         return 1;
 754         }
 755         return 0;
 756 }
 757 EXPORT_SYMBOL(radix_tree_tagged);
 758
 759 static void
 760 radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags)
 761 {
 762         memset(node, 0, sizeof(struct radix_tree_node));
 763 }
 764
 765 static __init unsigned long __maxindex(unsigned int height)
 766 {
 767         unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
 768         unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
 769
 770         if (tmp >= RADIX_TREE_INDEX_BITS)
 771                 index = ~0UL;
 772         return index;
 773 }
 774
 775 static __init void radix_tree_init_maxindex(void)
 776 {
 777         unsigned int i;
 778
 779         for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
 780                 height_to_maxindex[i] = __maxindex(i);
 781 }
 782
 783 #ifdef CONFIG_HOTPLUG_CPU
 784 static int radix_tree_callback(struct notifier_block *nfb,
 785                             unsigned long action,
 786                             void *hcpu)
 787 {
 788        int cpu = (long)hcpu;
 789        struct radix_tree_preload *rtp;
 790
 791        /* Free per-cpu pool of perloaded nodes */
 792        if (action == CPU_DEAD) {
 793                rtp = &per_cpu(radix_tree_preloads, cpu);
 794                while (rtp->nr) {
 795                        kmem_cache_free(radix_tree_node_cachep,
 796                                        rtp->nodes[rtp->nr-1]);
 797                        rtp->nodes[rtp->nr-1] = NULL;
 798                        rtp->nr--;
 799                }
 800        }
 801        return NOTIFY_OK;
 802 }
 803 #endif /* CONFIG_HOTPLUG_CPU */
 804
 805 void __init radix_tree_init(void)
 806 {
 807         radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
 808                         sizeof(struct radix_tree_node), 0,
 809                         SLAB_PANIC, radix_tree_node_ctor, NULL);
 810         radix_tree_init_maxindex();
 811         hotcpu_notifier(radix_tree_callback, 0);
 812 }