git.oblomov.eu Git - linux-2.6/blob - 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 values:
 427  *
 428  *  0: tag not present
 429  *  1: tag present, set
 430  * -1: tag present, unset
 431  */
 432 int radix_tree_tag_get(struct radix_tree_root *root,
 433                         unsigned long index, int tag)
 434 {
 435         unsigned int height, shift;
 436         struct radix_tree_node *slot;
 437         int saw_unset_tag = 0;
 438
 439         height = root->height;
 440         if (index > radix_tree_maxindex(height))
 441                 return 0;
 442
 443         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 444         slot = root->rnode;
 445
 446         for ( ; ; ) {
 447                 int offset;
 448
 449                 if (slot == NULL)
 450                         return 0;
 451
 452                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 453
 454                 /*
 455                  * This is just a debug check.  Later, we can bale as soon as
 456                  * we see an unset tag.
 457                  */
 458                 if (!tag_get(slot, tag, offset))
 459                         saw_unset_tag = 1;
 460                 if (height == 1) {
 461                         int ret = tag_get(slot, tag, offset);
 462
 463                         BUG_ON(ret && saw_unset_tag);
 464                         return ret ? 1 : -1;
 465                 }
 466                 slot = slot->slots[offset];
 467                 shift -= RADIX_TREE_MAP_SHIFT;
 468                 height--;
 469         }
 470 }
 471 EXPORT_SYMBOL(radix_tree_tag_get);
 472 #endif
 473
 474 static unsigned int
 475 __lookup(struct radix_tree_root *root, void **results, unsigned long index,
 476         unsigned int max_items, unsigned long *next_index)
 477 {
 478         unsigned int nr_found = 0;
 479         unsigned int shift, height;
 480         struct radix_tree_node *slot;
 481         unsigned long i;
 482
 483         height = root->height;
 484         if (height == 0)
 485                 goto out;
 486
 487         shift = (height-1) * RADIX_TREE_MAP_SHIFT;
 488         slot = root->rnode;
 489
 490         for ( ; height > 1; height--) {
 491
 492                 for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
 493                                 i < RADIX_TREE_MAP_SIZE; i++) {
 494                         if (slot->slots[i] != NULL)
 495                                 break;
 496                         index &= ~((1UL << shift) - 1);
 497                         index += 1UL << shift;
 498                         if (index == 0)
 499                                 goto out;       /* 32-bit wraparound */
 500                 }
 501                 if (i == RADIX_TREE_MAP_SIZE)
 502                         goto out;
 503
 504                 shift -= RADIX_TREE_MAP_SHIFT;
 505                 slot = slot->slots[i];
 506         }
 507
 508         /* Bottom level: grab some items */
 509         for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
 510                 index++;
 511                 if (slot->slots[i]) {
 512                         results[nr_found++] = slot->slots[i];
 513                         if (nr_found == max_items)
 514                                 goto out;
 515                 }
 516         }
 517 out:
 518         *next_index = index;
 519         return nr_found;
 520 }
 521
 522 /**
 523  *      radix_tree_gang_lookup - perform multiple lookup on a radix tree
 524  *      @root:          radix tree root
 525  *      @results:       where the results of the lookup are placed
 526  *      @first_index:   start the lookup from this key
 527  *      @max_items:     place up to this many items at *results
 528  *
 529  *      Performs an index-ascending scan of the tree for present items.  Places
 530  *      them at *@results and returns the number of items which were placed at
 531  *      *@results.
 532  *
 533  *      The implementation is naive.
 534  */
 535 unsigned int
 536 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 537                         unsigned long first_index, unsigned int max_items)
 538 {
 539         const unsigned long max_index = radix_tree_maxindex(root->height);
 540         unsigned long cur_index = first_index;
 541         unsigned int ret = 0;
 542
 543         while (ret < max_items) {
 544                 unsigned int nr_found;
 545                 unsigned long next_index;       /* Index of next search */
 546
 547                 if (cur_index > max_index)
 548                         break;
 549                 nr_found = __lookup(root, results + ret, cur_index,
 550                                         max_items - ret, &next_index);
 551                 ret += nr_found;
 552                 if (next_index == 0)
 553                         break;
 554                 cur_index = next_index;
 555         }
 556         return ret;
 557 }
 558 EXPORT_SYMBOL(radix_tree_gang_lookup);
 559
 560 /*
 561  * FIXME: the two tag_get()s here should use find_next_bit() instead of
 562  * open-coding the search.
 563  */
 564 static unsigned int
 565 __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
 566         unsigned int max_items, unsigned long *next_index, int tag)
 567 {
 568         unsigned int nr_found = 0;
 569         unsigned int shift;
 570         unsigned int height = root->height;
 571         struct radix_tree_node *slot;
 572
 573         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 574         slot = root->rnode;
 575
 576         while (height > 0) {
 577                 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
 578
 579                 for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
 580                         if (tag_get(slot, tag, i)) {
 581                                 BUG_ON(slot->slots[i] == NULL);
 582                                 break;
 583                         }
 584                         index &= ~((1UL << shift) - 1);
 585                         index += 1UL << shift;
 586                         if (index == 0)
 587                                 goto out;       /* 32-bit wraparound */
 588                 }
 589                 if (i == RADIX_TREE_MAP_SIZE)
 590                         goto out;
 591                 height--;
 592                 if (height == 0) {      /* Bottom level: grab some items */
 593                         unsigned long j = index & RADIX_TREE_MAP_MASK;
 594
 595                         for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
 596                                 index++;
 597                                 if (tag_get(slot, tag, j)) {
 598                                         BUG_ON(slot->slots[j] == NULL);
 599                                         results[nr_found++] = slot->slots[j];
 600                                         if (nr_found == max_items)
 601                                                 goto out;
 602                                 }
 603                         }
 604                 }
 605                 shift -= RADIX_TREE_MAP_SHIFT;
 606                 slot = slot->slots[i];
 607         }
 608 out:
 609         *next_index = index;
 610         return nr_found;
 611 }
 612
 613 /**
 614  *      radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
 615  *                                   based on a tag
 616  *      @root:          radix tree root
 617  *      @results:       where the results of the lookup are placed
 618  *      @first_index:   start the lookup from this key
 619  *      @max_items:     place up to this many items at *results
 620  *      @tag:           the tag index
 621  *
 622  *      Performs an index-ascending scan of the tree for present items which
 623  *      have the tag indexed by @tag set.  Places the items at *@results and
 624  *      returns the number of items which were placed at *@results.
 625  */
 626 unsigned int
 627 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
 628                 unsigned long first_index, unsigned int max_items, int tag)
 629 {
 630         const unsigned long max_index = radix_tree_maxindex(root->height);
 631         unsigned long cur_index = first_index;
 632         unsigned int ret = 0;
 633
 634         while (ret < max_items) {
 635                 unsigned int nr_found;
 636                 unsigned long next_index;       /* Index of next search */
 637
 638                 if (cur_index > max_index)
 639                         break;
 640                 nr_found = __lookup_tag(root, results + ret, cur_index,
 641                                         max_items - ret, &next_index, tag);
 642                 ret += nr_found;
 643                 if (next_index == 0)
 644                         break;
 645                 cur_index = next_index;
 646         }
 647         return ret;
 648 }
 649 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
 650
 651 /**
 652  *      radix_tree_delete    -    delete an item from a radix tree
 653  *      @root:          radix tree root
 654  *      @index:         index key
 655  *
 656  *      Remove the item at @index from the radix tree rooted at @root.
 657  *
 658  *      Returns the address of the deleted item, or NULL if it was not present.
 659  */
 660 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
 661 {
 662         struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
 663         struct radix_tree_path *orig_pathp;
 664         struct radix_tree_node *slot;
 665         unsigned int height, shift;
 666         void *ret = NULL;
 667         char tags[RADIX_TREE_TAGS];
 668         int nr_cleared_tags;
 669
 670         height = root->height;
 671         if (index > radix_tree_maxindex(height))
 672                 goto out;
 673
 674         shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
 675         pathp->node = NULL;
 676         slot = root->rnode;
 677
 678         for ( ; height > 0; height--) {
 679                 int offset;
 680
 681                 if (slot == NULL)
 682                         goto out;
 683
 684                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
 685                 pathp[1].offset = offset;
 686                 pathp[1].node = slot;
 687                 slot = slot->slots[offset];
 688                 pathp++;
 689                 shift -= RADIX_TREE_MAP_SHIFT;
 690         }
 691
 692         ret = slot;
 693         if (ret == NULL)
 694                 goto out;
 695
 696         orig_pathp = pathp;
 697
 698         /*
 699          * Clear all tags associated with the just-deleted item
 700          */
 701         memset(tags, 0, sizeof(tags));
 702         do {
 703                 int tag;
 704
 705                 nr_cleared_tags = RADIX_TREE_TAGS;
 706                 for (tag = 0; tag < RADIX_TREE_TAGS; tag++) {
 707                         int idx;
 708
 709                         if (tags[tag])
 710                                 continue;
 711
 712                         tag_clear(pathp->node, tag, pathp->offset);
 713
 714                         for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 715                                 if (pathp->node->tags[tag][idx]) {
 716                                         tags[tag] = 1;
 717                                         nr_cleared_tags--;
 718                                         break;
 719                                 }
 720                         }
 721                 }
 722                 pathp--;
 723         } while (pathp->node && nr_cleared_tags);
 724
 725         /* Now free the nodes we do not need anymore */
 726         for (pathp = orig_pathp; pathp->node; pathp--) {
 727                 pathp->node->slots[pathp->offset] = NULL;
 728                 if (--pathp->node->count)
 729                         goto out;
 730
 731                 /* Node with zero slots in use so free it */
 732                 radix_tree_node_free(pathp->node);
 733         }
 734         root->rnode = NULL;
 735         root->height = 0;
 736 out:
 737         return ret;
 738 }
 739 EXPORT_SYMBOL(radix_tree_delete);
 740
 741 /**
 742  *      radix_tree_tagged - test whether any items in the tree are tagged
 743  *      @root:          radix tree root
 744  *      @tag:           tag to test
 745  */
 746 int radix_tree_tagged(struct radix_tree_root *root, int tag)
 747 {
 748         int idx;
 749
 750         if (!root->rnode)
 751                 return 0;
 752         for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
 753                 if (root->rnode->tags[tag][idx])
 754                         return 1;
 755         }
 756         return 0;
 757 }
 758 EXPORT_SYMBOL(radix_tree_tagged);
 759
 760 static void
 761 radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags)
 762 {
 763         memset(node, 0, sizeof(struct radix_tree_node));
 764 }
 765
 766 static __init unsigned long __maxindex(unsigned int height)
 767 {
 768         unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
 769         unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
 770
 771         if (tmp >= RADIX_TREE_INDEX_BITS)
 772                 index = ~0UL;
 773         return index;
 774 }
 775
 776 static __init void radix_tree_init_maxindex(void)
 777 {
 778         unsigned int i;
 779
 780         for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
 781                 height_to_maxindex[i] = __maxindex(i);
 782 }
 783
 784 #ifdef CONFIG_HOTPLUG_CPU
 785 static int radix_tree_callback(struct notifier_block *nfb,
 786                             unsigned long action,
 787                             void *hcpu)
 788 {
 789        int cpu = (long)hcpu;
 790        struct radix_tree_preload *rtp;
 791
 792        /* Free per-cpu pool of perloaded nodes */
 793        if (action == CPU_DEAD) {
 794                rtp = &per_cpu(radix_tree_preloads, cpu);
 795                while (rtp->nr) {
 796                        kmem_cache_free(radix_tree_node_cachep,
 797                                        rtp->nodes[rtp->nr-1]);
 798                        rtp->nodes[rtp->nr-1] = NULL;
 799                        rtp->nr--;
 800                }
 801        }
 802        return NOTIFY_OK;
 803 }
 804 #endif /* CONFIG_HOTPLUG_CPU */
 805
 806 void __init radix_tree_init(void)
 807 {
 808         radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
 809                         sizeof(struct radix_tree_node), 0,
 810                         SLAB_PANIC, radix_tree_node_ctor, NULL);
 811         radix_tree_init_maxindex();
 812         hotcpu_notifier(radix_tree_callback, 0);
 813 }