blob: 3291a8e37490ecc9d9221f389d26d02c0ae1f103 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
Christoph Lametercde53532008-07-04 09:59:22 -07004 * Copyright (C) 2005 SGI, Christoph Lameter
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08005 * Copyright (C) 2006 Nick Piggin
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -07006 * Copyright (C) 2012 Konstantin Khlebnikov
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2, or (at
11 * your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#include <linux/errno.h>
24#include <linux/init.h>
25#include <linux/kernel.h>
Paul Gortmaker8bc3bcc2011-11-16 21:29:17 -050026#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/radix-tree.h>
28#include <linux/percpu.h>
29#include <linux/slab.h>
Catalin Marinasce80b062014-06-06 14:38:18 -070030#include <linux/kmemleak.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/notifier.h>
32#include <linux/cpu.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033#include <linux/string.h>
34#include <linux/bitops.h>
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080035#include <linux/rcupdate.h>
Jan Kara5e4c0d972013-09-11 14:26:05 -070036#include <linux/hardirq.h> /* in_interrupt() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38
Jeff Moyer26fb1582007-10-16 01:24:49 -070039/*
40 * The height_to_maxindex array needs to be one deeper than the maximum
41 * path as height 0 holds only 1 entry.
42 */
43static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45/*
46 * Radix tree node cache.
47 */
Christoph Lametere18b8902006-12-06 20:33:20 -080048static struct kmem_cache *radix_tree_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50/*
Nick Piggin55368052012-05-29 15:07:34 -070051 * The radix tree is variable-height, so an insert operation not only has
52 * to build the branch to its corresponding item, it also has to build the
53 * branch to existing items if the size has to be increased (by
54 * radix_tree_extend).
55 *
56 * The worst case is a zero height tree with just a single item at index 0,
57 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
58 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
59 * Hence:
60 */
61#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
62
63/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 * Per-cpu pool of preloaded nodes
65 */
66struct radix_tree_preload {
67 int nr;
Nick Piggin55368052012-05-29 15:07:34 -070068 struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070069};
Harvey Harrison8cef7d52009-01-06 14:40:50 -080070static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Nick Piggin27d20fd2010-11-11 14:05:19 -080072static inline void *ptr_to_indirect(void *ptr)
73{
74 return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
75}
76
77static inline void *indirect_to_ptr(void *ptr)
78{
79 return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
80}
81
Nick Piggin612d6c12006-06-23 02:03:22 -070082static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
83{
84 return root->gfp_mask & __GFP_BITS_MASK;
85}
86
Nick Piggin643b52b2008-06-12 15:21:52 -070087static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
88 int offset)
89{
90 __set_bit(offset, node->tags[tag]);
91}
92
93static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
94 int offset)
95{
96 __clear_bit(offset, node->tags[tag]);
97}
98
99static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
100 int offset)
101{
102 return test_bit(offset, node->tags[tag]);
103}
104
105static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
106{
107 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
108}
109
110static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
111{
112 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
113}
114
115static inline void root_tag_clear_all(struct radix_tree_root *root)
116{
117 root->gfp_mask &= __GFP_BITS_MASK;
118}
119
120static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
121{
122 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
123}
124
125/*
126 * Returns 1 if any slot in the node has this tag set.
127 * Otherwise returns 0.
128 */
129static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
130{
131 int idx;
132 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
133 if (node->tags[tag][idx])
134 return 1;
135 }
136 return 0;
137}
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700138
139/**
140 * radix_tree_find_next_bit - find the next set bit in a memory region
141 *
142 * @addr: The address to base the search on
143 * @size: The bitmap size in bits
144 * @offset: The bitnumber to start searching at
145 *
146 * Unrollable variant of find_next_bit() for constant size arrays.
147 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
148 * Returns next bit offset, or size if nothing found.
149 */
150static __always_inline unsigned long
151radix_tree_find_next_bit(const unsigned long *addr,
152 unsigned long size, unsigned long offset)
153{
154 if (!__builtin_constant_p(size))
155 return find_next_bit(addr, size, offset);
156
157 if (offset < size) {
158 unsigned long tmp;
159
160 addr += offset / BITS_PER_LONG;
161 tmp = *addr >> (offset % BITS_PER_LONG);
162 if (tmp)
163 return __ffs(tmp) + offset;
164 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
165 while (offset < size) {
166 tmp = *++addr;
167 if (tmp)
168 return __ffs(tmp) + offset;
169 offset += BITS_PER_LONG;
170 }
171 }
172 return size;
173}
174
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175/*
176 * This assumes that the caller has performed appropriate preallocation, and
177 * that the caller has pinned this thread of control to the current CPU.
178 */
179static struct radix_tree_node *
180radix_tree_node_alloc(struct radix_tree_root *root)
181{
Nick Piggine2848a02008-02-04 22:29:10 -0800182 struct radix_tree_node *ret = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700183 gfp_t gfp_mask = root_gfp_mask(root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
Jan Kara5e4c0d972013-09-11 14:26:05 -0700185 /*
186 * Preload code isn't irq safe and it doesn't make sence to use
187 * preloading in the interrupt anyway as all the allocations have to
188 * be atomic. So just do normal allocation when in interrupt.
189 */
190 if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 struct radix_tree_preload *rtp;
192
Nick Piggine2848a02008-02-04 22:29:10 -0800193 /*
194 * Provided the caller has preloaded here, we will always
195 * succeed in getting a node here (and never reach
196 * kmem_cache_alloc)
197 */
Christoph Lameter7c8e0182014-06-04 16:07:56 -0700198 rtp = this_cpu_ptr(&radix_tree_preloads);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 if (rtp->nr) {
200 ret = rtp->nodes[rtp->nr - 1];
201 rtp->nodes[rtp->nr - 1] = NULL;
202 rtp->nr--;
203 }
Catalin Marinasce80b062014-06-06 14:38:18 -0700204 /*
205 * Update the allocation stack trace as this is more useful
206 * for debugging.
207 */
208 kmemleak_update_trace(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 }
Nick Piggine2848a02008-02-04 22:29:10 -0800210 if (ret == NULL)
Christoph Lameter488514d2008-04-28 02:12:05 -0700211 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Nick Piggine2848a02008-02-04 22:29:10 -0800212
Nick Pigginc0bc9872007-10-16 01:24:42 -0700213 BUG_ON(radix_tree_is_indirect_ptr(ret));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 return ret;
215}
216
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800217static void radix_tree_node_rcu_free(struct rcu_head *head)
218{
219 struct radix_tree_node *node =
220 container_of(head, struct radix_tree_node, rcu_head);
Dave Chinnerb6dd0862010-08-23 10:33:19 +1000221 int i;
Nick Piggin643b52b2008-06-12 15:21:52 -0700222
223 /*
224 * must only free zeroed nodes into the slab. radix_tree_shrink
225 * can leave us with a non-NULL entry in the first slot, so clear
226 * that here to make sure.
227 */
Dave Chinnerb6dd0862010-08-23 10:33:19 +1000228 for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
229 tag_clear(node, i, 0);
230
Nick Piggin643b52b2008-06-12 15:21:52 -0700231 node->slots[0] = NULL;
232 node->count = 0;
233
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800234 kmem_cache_free(radix_tree_node_cachep, node);
235}
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237static inline void
238radix_tree_node_free(struct radix_tree_node *node)
239{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800240 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241}
242
243/*
244 * Load up this CPU's radix_tree_node buffer with sufficient objects to
245 * ensure that the addition of a single element in the tree cannot fail. On
246 * success, return zero, with preemption disabled. On error, return -ENOMEM
247 * with preemption not disabled.
David Howellsb34df792009-11-19 18:11:14 +0000248 *
249 * To make use of this facility, the radix tree must be initialised without
250 * __GFP_WAIT being passed to INIT_RADIX_TREE().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 */
Jan Kara5e4c0d972013-09-11 14:26:05 -0700252static int __radix_tree_preload(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253{
254 struct radix_tree_preload *rtp;
255 struct radix_tree_node *node;
256 int ret = -ENOMEM;
257
258 preempt_disable();
Christoph Lameter7c8e0182014-06-04 16:07:56 -0700259 rtp = this_cpu_ptr(&radix_tree_preloads);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
261 preempt_enable();
Christoph Lameter488514d2008-04-28 02:12:05 -0700262 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 if (node == NULL)
264 goto out;
265 preempt_disable();
Christoph Lameter7c8e0182014-06-04 16:07:56 -0700266 rtp = this_cpu_ptr(&radix_tree_preloads);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
268 rtp->nodes[rtp->nr++] = node;
269 else
270 kmem_cache_free(radix_tree_node_cachep, node);
271 }
272 ret = 0;
273out:
274 return ret;
275}
Jan Kara5e4c0d972013-09-11 14:26:05 -0700276
277/*
278 * Load up this CPU's radix_tree_node buffer with sufficient objects to
279 * ensure that the addition of a single element in the tree cannot fail. On
280 * success, return zero, with preemption disabled. On error, return -ENOMEM
281 * with preemption not disabled.
282 *
283 * To make use of this facility, the radix tree must be initialised without
284 * __GFP_WAIT being passed to INIT_RADIX_TREE().
285 */
286int radix_tree_preload(gfp_t gfp_mask)
287{
288 /* Warn on non-sensical use... */
289 WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT));
290 return __radix_tree_preload(gfp_mask);
291}
David Chinnerd7f09232007-07-14 16:05:04 +1000292EXPORT_SYMBOL(radix_tree_preload);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
Nick Piggin6e954b92006-01-08 01:01:40 -0800294/*
Jan Kara5e4c0d972013-09-11 14:26:05 -0700295 * The same as above function, except we don't guarantee preloading happens.
296 * We do it, if we decide it helps. On success, return zero with preemption
297 * disabled. On error, return -ENOMEM with preemption not disabled.
298 */
299int radix_tree_maybe_preload(gfp_t gfp_mask)
300{
301 if (gfp_mask & __GFP_WAIT)
302 return __radix_tree_preload(gfp_mask);
303 /* Preloading doesn't help anything with this gfp mask, skip it */
304 preempt_disable();
305 return 0;
306}
307EXPORT_SYMBOL(radix_tree_maybe_preload);
308
309/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 * Return the maximum key which can be store into a
311 * radix tree with height HEIGHT.
312 */
313static inline unsigned long radix_tree_maxindex(unsigned int height)
314{
315 return height_to_maxindex[height];
316}
317
318/*
319 * Extend a radix tree so it can store key @index.
320 */
321static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
322{
323 struct radix_tree_node *node;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800324 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 unsigned int height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 int tag;
327
328 /* Figure out what the height should be. */
329 height = root->height + 1;
330 while (index > radix_tree_maxindex(height))
331 height++;
332
333 if (root->rnode == NULL) {
334 root->height = height;
335 goto out;
336 }
337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 do {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800339 unsigned int newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 if (!(node = radix_tree_node_alloc(root)))
341 return -ENOMEM;
342
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 /* Propagate the aggregated tag info into the new root */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800344 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -0700345 if (root_tag_get(root, tag))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 tag_set(node, tag, 0);
347 }
348
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800349 /* Increase the height. */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800350 newheight = root->height+1;
Johannes Weiner449dd692014-04-03 14:47:56 -0700351 BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK);
352 node->path = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 node->count = 1;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800354 node->parent = NULL;
355 slot = root->rnode;
356 if (newheight > 1) {
357 slot = indirect_to_ptr(slot);
358 slot->parent = node;
359 }
360 node->slots[0] = slot;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800361 node = ptr_to_indirect(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800362 rcu_assign_pointer(root->rnode, node);
363 root->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 } while (height > root->height);
365out:
366 return 0;
367}
368
369/**
Johannes Weiner139e5612014-04-03 14:47:54 -0700370 * __radix_tree_create - create a slot in a radix tree
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 * @root: radix tree root
372 * @index: index key
Johannes Weiner139e5612014-04-03 14:47:54 -0700373 * @nodep: returns node
374 * @slotp: returns slot
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 *
Johannes Weiner139e5612014-04-03 14:47:54 -0700376 * Create, if necessary, and return the node and slot for an item
377 * at position @index in the radix tree @root.
378 *
379 * Until there is more than one item in the tree, no nodes are
380 * allocated and @root->rnode is used as a direct slot instead of
381 * pointing to a node, in which case *@nodep will be NULL.
382 *
383 * Returns -ENOMEM, or 0 for success.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 */
Johannes Weiner139e5612014-04-03 14:47:54 -0700385int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
386 struct radix_tree_node **nodep, void ***slotp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387{
Christoph Lameter201b6262005-09-06 15:16:46 -0700388 struct radix_tree_node *node = NULL, *slot;
Johannes Weiner139e5612014-04-03 14:47:54 -0700389 unsigned int height, shift, offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 int error;
391
392 /* Make sure the tree is high enough. */
Nick Piggin612d6c12006-06-23 02:03:22 -0700393 if (index > radix_tree_maxindex(root->height)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 error = radix_tree_extend(root, index);
395 if (error)
396 return error;
397 }
398
Nick Piggin27d20fd2010-11-11 14:05:19 -0800399 slot = indirect_to_ptr(root->rnode);
Nick Pigginc0bc9872007-10-16 01:24:42 -0700400
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 height = root->height;
402 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
403
404 offset = 0; /* uninitialised var warning */
Nick Piggin612d6c12006-06-23 02:03:22 -0700405 while (height > 0) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700406 if (slot == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 /* Have to add a child node. */
Christoph Lameter201b6262005-09-06 15:16:46 -0700408 if (!(slot = radix_tree_node_alloc(root)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 return -ENOMEM;
Johannes Weiner449dd692014-04-03 14:47:56 -0700410 slot->path = height;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800411 slot->parent = node;
Christoph Lameter201b6262005-09-06 15:16:46 -0700412 if (node) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800413 rcu_assign_pointer(node->slots[offset], slot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 node->count++;
Johannes Weiner449dd692014-04-03 14:47:56 -0700415 slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT;
Christoph Lameter201b6262005-09-06 15:16:46 -0700416 } else
Nick Piggin27d20fd2010-11-11 14:05:19 -0800417 rcu_assign_pointer(root->rnode, ptr_to_indirect(slot));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 }
419
420 /* Go a level down */
421 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Christoph Lameter201b6262005-09-06 15:16:46 -0700422 node = slot;
423 slot = node->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 shift -= RADIX_TREE_MAP_SHIFT;
425 height--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700426 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427
Johannes Weiner139e5612014-04-03 14:47:54 -0700428 if (nodep)
429 *nodep = node;
430 if (slotp)
431 *slotp = node ? node->slots + offset : (void **)&root->rnode;
432 return 0;
433}
434
435/**
436 * radix_tree_insert - insert into a radix tree
437 * @root: radix tree root
438 * @index: index key
439 * @item: item to insert
440 *
441 * Insert an item into the radix tree at position @index.
442 */
443int radix_tree_insert(struct radix_tree_root *root,
444 unsigned long index, void *item)
445{
446 struct radix_tree_node *node;
447 void **slot;
448 int error;
449
450 BUG_ON(radix_tree_is_indirect_ptr(item));
451
452 error = __radix_tree_create(root, index, &node, &slot);
453 if (error)
454 return error;
455 if (*slot != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 return -EEXIST;
Johannes Weiner139e5612014-04-03 14:47:54 -0700457 rcu_assign_pointer(*slot, item);
Christoph Lameter201b6262005-09-06 15:16:46 -0700458
Nick Piggin612d6c12006-06-23 02:03:22 -0700459 if (node) {
460 node->count++;
Johannes Weiner139e5612014-04-03 14:47:54 -0700461 BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
462 BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
Nick Piggin612d6c12006-06-23 02:03:22 -0700463 } else {
Nick Piggin612d6c12006-06-23 02:03:22 -0700464 BUG_ON(root_tag_get(root, 0));
465 BUG_ON(root_tag_get(root, 1));
466 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 return 0;
469}
470EXPORT_SYMBOL(radix_tree_insert);
471
Johannes Weiner139e5612014-04-03 14:47:54 -0700472/**
473 * __radix_tree_lookup - lookup an item in a radix tree
474 * @root: radix tree root
475 * @index: index key
476 * @nodep: returns node
477 * @slotp: returns slot
478 *
479 * Lookup and return the item at position @index in the radix
480 * tree @root.
481 *
482 * Until there is more than one item in the tree, no nodes are
483 * allocated and @root->rnode is used as a direct slot instead of
484 * pointing to a node, in which case *@nodep will be NULL.
Hans Reisera4331362005-11-07 00:59:29 -0800485 */
Johannes Weiner139e5612014-04-03 14:47:54 -0700486void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
487 struct radix_tree_node **nodep, void ***slotp)
Hans Reisera4331362005-11-07 00:59:29 -0800488{
Johannes Weiner139e5612014-04-03 14:47:54 -0700489 struct radix_tree_node *node, *parent;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800490 unsigned int height, shift;
Johannes Weiner139e5612014-04-03 14:47:54 -0700491 void **slot;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800492
Paul E. McKenney2676a582010-02-22 17:04:54 -0800493 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800494 if (node == NULL)
495 return NULL;
496
Nick Pigginc0bc9872007-10-16 01:24:42 -0700497 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800498 if (index > 0)
499 return NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -0700500
501 if (nodep)
502 *nodep = NULL;
503 if (slotp)
504 *slotp = (void **)&root->rnode;
505 return node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800506 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800507 node = indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800508
Johannes Weiner449dd692014-04-03 14:47:56 -0700509 height = node->path & RADIX_TREE_HEIGHT_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800510 if (index > radix_tree_maxindex(height))
511 return NULL;
512
513 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
514
515 do {
Johannes Weiner139e5612014-04-03 14:47:54 -0700516 parent = node;
517 slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK);
Paul E. McKenney2676a582010-02-22 17:04:54 -0800518 node = rcu_dereference_raw(*slot);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800519 if (node == NULL)
520 return NULL;
521
522 shift -= RADIX_TREE_MAP_SHIFT;
523 height--;
524 } while (height > 0);
525
Johannes Weiner139e5612014-04-03 14:47:54 -0700526 if (nodep)
527 *nodep = parent;
528 if (slotp)
529 *slotp = slot;
530 return node;
Huang Shijieb72b71c2009-06-16 15:33:42 -0700531}
532
533/**
534 * radix_tree_lookup_slot - lookup a slot in a radix tree
535 * @root: radix tree root
536 * @index: index key
537 *
538 * Returns: the slot corresponding to the position @index in the
539 * radix tree @root. This is useful for update-if-exists operations.
540 *
541 * This function can be called under rcu_read_lock iff the slot is not
542 * modified by radix_tree_replace_slot, otherwise it must be called
543 * exclusive from other writers. Any dereference of the slot must be done
544 * using radix_tree_deref_slot.
545 */
546void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
547{
Johannes Weiner139e5612014-04-03 14:47:54 -0700548 void **slot;
549
550 if (!__radix_tree_lookup(root, index, NULL, &slot))
551 return NULL;
552 return slot;
Hans Reisera4331362005-11-07 00:59:29 -0800553}
554EXPORT_SYMBOL(radix_tree_lookup_slot);
555
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556/**
557 * radix_tree_lookup - perform lookup operation on a radix tree
558 * @root: radix tree root
559 * @index: index key
560 *
561 * Lookup the item at the position @index in the radix tree @root.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800562 *
563 * This function can be called under rcu_read_lock, however the caller
564 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
565 * them safely). No RCU barriers are required to access or modify the
566 * returned item, however.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 */
568void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
569{
Johannes Weiner139e5612014-04-03 14:47:54 -0700570 return __radix_tree_lookup(root, index, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571}
572EXPORT_SYMBOL(radix_tree_lookup);
573
574/**
575 * radix_tree_tag_set - set a tag on a radix tree node
576 * @root: radix tree root
577 * @index: index key
578 * @tag: tag index
579 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800580 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
581 * corresponding to @index in the radix tree. From
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 * the root all the way down to the leaf node.
583 *
584 * Returns the address of the tagged item. Setting a tag on a not-present
585 * item is a bug.
586 */
587void *radix_tree_tag_set(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800588 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589{
590 unsigned int height, shift;
Christoph Lameter201b6262005-09-06 15:16:46 -0700591 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
593 height = root->height;
Peter Zijlstra4c91c362006-06-23 02:03:25 -0700594 BUG_ON(index > radix_tree_maxindex(height));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595
Nick Piggin27d20fd2010-11-11 14:05:19 -0800596 slot = indirect_to_ptr(root->rnode);
Nick Piggin612d6c12006-06-23 02:03:22 -0700597 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598
599 while (height > 0) {
600 int offset;
601
602 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggind5274262006-01-08 01:01:41 -0800603 if (!tag_get(slot, tag, offset))
604 tag_set(slot, tag, offset);
Christoph Lameter201b6262005-09-06 15:16:46 -0700605 slot = slot->slots[offset];
606 BUG_ON(slot == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 shift -= RADIX_TREE_MAP_SHIFT;
608 height--;
609 }
610
Nick Piggin612d6c12006-06-23 02:03:22 -0700611 /* set the root's tag bit */
612 if (slot && !root_tag_get(root, tag))
613 root_tag_set(root, tag);
614
Christoph Lameter201b6262005-09-06 15:16:46 -0700615 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616}
617EXPORT_SYMBOL(radix_tree_tag_set);
618
619/**
620 * radix_tree_tag_clear - clear a tag on a radix tree node
621 * @root: radix tree root
622 * @index: index key
623 * @tag: tag index
624 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800625 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
626 * corresponding to @index in the radix tree. If
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 * this causes the leaf node to have no tags set then clear the tag in the
628 * next-to-leaf node, etc.
629 *
630 * Returns the address of the tagged item on success, else NULL. ie:
631 * has the same return value and semantics as radix_tree_lookup().
632 */
633void *radix_tree_tag_clear(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800634 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635{
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800636 struct radix_tree_node *node = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700637 struct radix_tree_node *slot = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 unsigned int height, shift;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800639 int uninitialized_var(offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640
641 height = root->height;
642 if (index > radix_tree_maxindex(height))
643 goto out;
644
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800645 shift = height * RADIX_TREE_MAP_SHIFT;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800646 slot = indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800648 while (shift) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700649 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 goto out;
651
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 shift -= RADIX_TREE_MAP_SHIFT;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800653 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
654 node = slot;
655 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 }
657
Nick Piggin612d6c12006-06-23 02:03:22 -0700658 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 goto out;
660
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800661 while (node) {
662 if (!tag_get(node, tag, offset))
Nick Piggind5274262006-01-08 01:01:41 -0800663 goto out;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800664 tag_clear(node, tag, offset);
665 if (any_tag_set(node, tag))
Nick Piggin6e954b92006-01-08 01:01:40 -0800666 goto out;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800667
668 index >>= RADIX_TREE_MAP_SHIFT;
669 offset = index & RADIX_TREE_MAP_MASK;
670 node = node->parent;
Nick Piggin612d6c12006-06-23 02:03:22 -0700671 }
672
673 /* clear the root's tag bit */
674 if (root_tag_get(root, tag))
675 root_tag_clear(root, tag);
676
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677out:
Nick Piggin612d6c12006-06-23 02:03:22 -0700678 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679}
680EXPORT_SYMBOL(radix_tree_tag_clear);
681
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682/**
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700683 * radix_tree_tag_get - get a tag on a radix tree node
684 * @root: radix tree root
685 * @index: index key
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800686 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 *
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700688 * Return values:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 *
Nick Piggin612d6c12006-06-23 02:03:22 -0700690 * 0: tag not present or not set
691 * 1: tag set
David Howellsce826532010-04-06 22:36:20 +0100692 *
693 * Note that the return value of this function may not be relied on, even if
694 * the RCU lock is held, unless tag modification and node deletion are excluded
695 * from concurrency.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 */
697int radix_tree_tag_get(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800698 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699{
700 unsigned int height, shift;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800701 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
Nick Piggin612d6c12006-06-23 02:03:22 -0700703 /* check the root's tag bit */
704 if (!root_tag_get(root, tag))
705 return 0;
706
Paul E. McKenney2676a582010-02-22 17:04:54 -0800707 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800708 if (node == NULL)
709 return 0;
710
Nick Pigginc0bc9872007-10-16 01:24:42 -0700711 if (!radix_tree_is_indirect_ptr(node))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800712 return (index == 0);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800713 node = indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800714
Johannes Weiner449dd692014-04-03 14:47:56 -0700715 height = node->path & RADIX_TREE_HEIGHT_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800716 if (index > radix_tree_maxindex(height))
717 return 0;
Nick Piggin612d6c12006-06-23 02:03:22 -0700718
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
721 for ( ; ; ) {
722 int offset;
723
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800724 if (node == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 return 0;
726
727 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800728 if (!tag_get(node, tag, offset))
Hugh Dickins3fa36ac2011-10-31 17:07:02 -0700729 return 0;
David Howellsce826532010-04-06 22:36:20 +0100730 if (height == 1)
Hugh Dickins3fa36ac2011-10-31 17:07:02 -0700731 return 1;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800732 node = rcu_dereference_raw(node->slots[offset]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 shift -= RADIX_TREE_MAP_SHIFT;
734 height--;
735 }
736}
737EXPORT_SYMBOL(radix_tree_tag_get);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700739/**
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700740 * radix_tree_next_chunk - find next chunk of slots for iteration
741 *
742 * @root: radix tree root
743 * @iter: iterator state
744 * @flags: RADIX_TREE_ITER_* flags and tag index
745 * Returns: pointer to chunk first slot, or NULL if iteration is over
746 */
747void **radix_tree_next_chunk(struct radix_tree_root *root,
748 struct radix_tree_iter *iter, unsigned flags)
749{
750 unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
751 struct radix_tree_node *rnode, *node;
Johannes Weiner449dd692014-04-03 14:47:56 -0700752 unsigned long index, offset, height;
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700753
754 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
755 return NULL;
756
757 /*
758 * Catch next_index overflow after ~0UL. iter->index never overflows
759 * during iterating; it can be zero only at the beginning.
760 * And we cannot overflow iter->next_index in a single step,
761 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
Konstantin Khlebnikovfffaee32012-06-05 21:36:33 +0400762 *
763 * This condition also used by radix_tree_next_slot() to stop
764 * contiguous iterating, and forbid swithing to the next chunk.
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700765 */
766 index = iter->next_index;
767 if (!index && iter->index)
768 return NULL;
769
770 rnode = rcu_dereference_raw(root->rnode);
771 if (radix_tree_is_indirect_ptr(rnode)) {
772 rnode = indirect_to_ptr(rnode);
773 } else if (rnode && !index) {
774 /* Single-slot tree */
775 iter->index = 0;
776 iter->next_index = 1;
777 iter->tags = 1;
778 return (void **)&root->rnode;
779 } else
780 return NULL;
781
782restart:
Johannes Weiner449dd692014-04-03 14:47:56 -0700783 height = rnode->path & RADIX_TREE_HEIGHT_MASK;
784 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700785 offset = index >> shift;
786
787 /* Index outside of the tree */
788 if (offset >= RADIX_TREE_MAP_SIZE)
789 return NULL;
790
791 node = rnode;
792 while (1) {
793 if ((flags & RADIX_TREE_ITER_TAGGED) ?
794 !test_bit(offset, node->tags[tag]) :
795 !node->slots[offset]) {
796 /* Hole detected */
797 if (flags & RADIX_TREE_ITER_CONTIG)
798 return NULL;
799
800 if (flags & RADIX_TREE_ITER_TAGGED)
801 offset = radix_tree_find_next_bit(
802 node->tags[tag],
803 RADIX_TREE_MAP_SIZE,
804 offset + 1);
805 else
806 while (++offset < RADIX_TREE_MAP_SIZE) {
807 if (node->slots[offset])
808 break;
809 }
810 index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
811 index += offset << shift;
812 /* Overflow after ~0UL */
813 if (!index)
814 return NULL;
815 if (offset == RADIX_TREE_MAP_SIZE)
816 goto restart;
817 }
818
819 /* This is leaf-node */
820 if (!shift)
821 break;
822
823 node = rcu_dereference_raw(node->slots[offset]);
824 if (node == NULL)
825 goto restart;
826 shift -= RADIX_TREE_MAP_SHIFT;
827 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
828 }
829
830 /* Update the iterator state */
831 iter->index = index;
832 iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1;
833
834 /* Construct iter->tags bit-mask from node->tags[tag] array */
835 if (flags & RADIX_TREE_ITER_TAGGED) {
836 unsigned tag_long, tag_bit;
837
838 tag_long = offset / BITS_PER_LONG;
839 tag_bit = offset % BITS_PER_LONG;
840 iter->tags = node->tags[tag][tag_long] >> tag_bit;
841 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
842 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
843 /* Pick tags from next element */
844 if (tag_bit)
845 iter->tags |= node->tags[tag][tag_long + 1] <<
846 (BITS_PER_LONG - tag_bit);
847 /* Clip chunk size, here only BITS_PER_LONG tags */
848 iter->next_index = index + BITS_PER_LONG;
849 }
850 }
851
852 return node->slots + offset;
853}
854EXPORT_SYMBOL(radix_tree_next_chunk);
855
856/**
Jan Karaebf8aa42010-08-09 17:19:11 -0700857 * radix_tree_range_tag_if_tagged - for each item in given range set given
858 * tag if item has another tag set
859 * @root: radix tree root
860 * @first_indexp: pointer to a starting index of a range to scan
861 * @last_index: last index of a range to scan
862 * @nr_to_tag: maximum number items to tag
863 * @iftag: tag index to test
864 * @settag: tag index to set if tested tag is set
865 *
866 * This function scans range of radix tree from first_index to last_index
867 * (inclusive). For each item in the range if iftag is set, the function sets
868 * also settag. The function stops either after tagging nr_to_tag items or
869 * after reaching last_index.
870 *
Dave Chinner144dcfc2010-08-23 10:33:53 +1000871 * The tags must be set from the leaf level only and propagated back up the
872 * path to the root. We must do this so that we resolve the full path before
873 * setting any tags on intermediate nodes. If we set tags as we descend, then
874 * we can get to the leaf node and find that the index that has the iftag
875 * set is outside the range we are scanning. This reults in dangling tags and
876 * can lead to problems with later tag operations (e.g. livelocks on lookups).
877 *
Jan Karaebf8aa42010-08-09 17:19:11 -0700878 * The function returns number of leaves where the tag was set and sets
879 * *first_indexp to the first unscanned index.
Jan Karad5ed3a42010-08-19 14:13:33 -0700880 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
881 * be prepared to handle that.
Jan Karaebf8aa42010-08-09 17:19:11 -0700882 */
883unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
884 unsigned long *first_indexp, unsigned long last_index,
885 unsigned long nr_to_tag,
886 unsigned int iftag, unsigned int settag)
887{
Dave Chinner144dcfc2010-08-23 10:33:53 +1000888 unsigned int height = root->height;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800889 struct radix_tree_node *node = NULL;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000890 struct radix_tree_node *slot;
891 unsigned int shift;
892 unsigned long tagged = 0;
893 unsigned long index = *first_indexp;
Jan Karaebf8aa42010-08-09 17:19:11 -0700894
895 last_index = min(last_index, radix_tree_maxindex(height));
896 if (index > last_index)
897 return 0;
898 if (!nr_to_tag)
899 return 0;
900 if (!root_tag_get(root, iftag)) {
901 *first_indexp = last_index + 1;
902 return 0;
903 }
904 if (height == 0) {
905 *first_indexp = last_index + 1;
906 root_tag_set(root, settag);
907 return 1;
908 }
909
910 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800911 slot = indirect_to_ptr(root->rnode);
Jan Karaebf8aa42010-08-09 17:19:11 -0700912
913 for (;;) {
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800914 unsigned long upindex;
Jan Karaebf8aa42010-08-09 17:19:11 -0700915 int offset;
916
917 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
918 if (!slot->slots[offset])
919 goto next;
920 if (!tag_get(slot, iftag, offset))
921 goto next;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800922 if (shift) {
Dave Chinner144dcfc2010-08-23 10:33:53 +1000923 /* Go down one level */
Dave Chinner144dcfc2010-08-23 10:33:53 +1000924 shift -= RADIX_TREE_MAP_SHIFT;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800925 node = slot;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000926 slot = slot->slots[offset];
927 continue;
Jan Karaebf8aa42010-08-09 17:19:11 -0700928 }
Dave Chinner144dcfc2010-08-23 10:33:53 +1000929
930 /* tag the leaf */
931 tagged++;
932 tag_set(slot, settag, offset);
933
934 /* walk back up the path tagging interior nodes */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800935 upindex = index;
936 while (node) {
937 upindex >>= RADIX_TREE_MAP_SHIFT;
938 offset = upindex & RADIX_TREE_MAP_MASK;
939
Dave Chinner144dcfc2010-08-23 10:33:53 +1000940 /* stop if we find a node with the tag already set */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800941 if (tag_get(node, settag, offset))
Dave Chinner144dcfc2010-08-23 10:33:53 +1000942 break;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800943 tag_set(node, settag, offset);
944 node = node->parent;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000945 }
946
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800947 /*
948 * Small optimization: now clear that node pointer.
949 * Since all of this slot's ancestors now have the tag set
950 * from setting it above, we have no further need to walk
951 * back up the tree setting tags, until we update slot to
952 * point to another radix_tree_node.
953 */
954 node = NULL;
955
Jan Karaebf8aa42010-08-09 17:19:11 -0700956next:
957 /* Go to next item at level determined by 'shift' */
958 index = ((index >> shift) + 1) << shift;
Jan Karad5ed3a42010-08-19 14:13:33 -0700959 /* Overflow can happen when last_index is ~0UL... */
960 if (index > last_index || !index)
Jan Karaebf8aa42010-08-09 17:19:11 -0700961 break;
962 if (tagged >= nr_to_tag)
963 break;
964 while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
965 /*
966 * We've fully scanned this node. Go up. Because
967 * last_index is guaranteed to be in the tree, what
968 * we do below cannot wander astray.
969 */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800970 slot = slot->parent;
Jan Karaebf8aa42010-08-09 17:19:11 -0700971 shift += RADIX_TREE_MAP_SHIFT;
972 }
973 }
974 /*
Toshiyuki Okajimaac15ee62011-01-25 15:07:32 -0800975 * We need not to tag the root tag if there is no tag which is set with
976 * settag within the range from *first_indexp to last_index.
Jan Karaebf8aa42010-08-09 17:19:11 -0700977 */
Toshiyuki Okajimaac15ee62011-01-25 15:07:32 -0800978 if (tagged > 0)
979 root_tag_set(root, settag);
Jan Karaebf8aa42010-08-09 17:19:11 -0700980 *first_indexp = index;
981
982 return tagged;
983}
984EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
985
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986/**
987 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
988 * @root: radix tree root
989 * @results: where the results of the lookup are placed
990 * @first_index: start the lookup from this key
991 * @max_items: place up to this many items at *results
992 *
993 * Performs an index-ascending scan of the tree for present items. Places
994 * them at *@results and returns the number of items which were placed at
995 * *@results.
996 *
997 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800998 *
999 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1000 * rcu_read_lock. In this case, rather than the returned results being
1001 * an atomic snapshot of the tree at a single point in time, the semantics
1002 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
1003 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 */
1005unsigned int
1006radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
1007 unsigned long first_index, unsigned int max_items)
1008{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001009 struct radix_tree_iter iter;
1010 void **slot;
1011 unsigned int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001013 if (unlikely(!max_items))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001014 return 0;
1015
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001016 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1017 results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
1018 if (!results[ret])
1019 continue;
1020 if (++ret == max_items)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001023
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 return ret;
1025}
1026EXPORT_SYMBOL(radix_tree_gang_lookup);
1027
Nick Piggin47feff22008-07-25 19:45:29 -07001028/**
1029 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1030 * @root: radix tree root
1031 * @results: where the results of the lookup are placed
Hugh Dickins63286502011-08-03 16:21:18 -07001032 * @indices: where their indices should be placed (but usually NULL)
Nick Piggin47feff22008-07-25 19:45:29 -07001033 * @first_index: start the lookup from this key
1034 * @max_items: place up to this many items at *results
1035 *
1036 * Performs an index-ascending scan of the tree for present items. Places
1037 * their slots at *@results and returns the number of items which were
1038 * placed at *@results.
1039 *
1040 * The implementation is naive.
1041 *
1042 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1043 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1044 * protection, radix_tree_deref_slot may fail requiring a retry.
1045 */
1046unsigned int
Hugh Dickins63286502011-08-03 16:21:18 -07001047radix_tree_gang_lookup_slot(struct radix_tree_root *root,
1048 void ***results, unsigned long *indices,
Nick Piggin47feff22008-07-25 19:45:29 -07001049 unsigned long first_index, unsigned int max_items)
1050{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001051 struct radix_tree_iter iter;
1052 void **slot;
1053 unsigned int ret = 0;
Nick Piggin47feff22008-07-25 19:45:29 -07001054
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001055 if (unlikely(!max_items))
Nick Piggin47feff22008-07-25 19:45:29 -07001056 return 0;
1057
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001058 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1059 results[ret] = slot;
Hugh Dickins63286502011-08-03 16:21:18 -07001060 if (indices)
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001061 indices[ret] = iter.index;
1062 if (++ret == max_items)
Nick Piggin47feff22008-07-25 19:45:29 -07001063 break;
Nick Piggin47feff22008-07-25 19:45:29 -07001064 }
1065
1066 return ret;
1067}
1068EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
1069
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070/**
1071 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1072 * based on a tag
1073 * @root: radix tree root
1074 * @results: where the results of the lookup are placed
1075 * @first_index: start the lookup from this key
1076 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001077 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 *
1079 * Performs an index-ascending scan of the tree for present items which
1080 * have the tag indexed by @tag set. Places the items at *@results and
1081 * returns the number of items which were placed at *@results.
1082 */
1083unsigned int
1084radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001085 unsigned long first_index, unsigned int max_items,
1086 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001088 struct radix_tree_iter iter;
1089 void **slot;
1090 unsigned int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001092 if (unlikely(!max_items))
Nick Piggin612d6c12006-06-23 02:03:22 -07001093 return 0;
1094
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001095 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1096 results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
1097 if (!results[ret])
1098 continue;
1099 if (++ret == max_items)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001102
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 return ret;
1104}
1105EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1106
1107/**
Nick Piggin47feff22008-07-25 19:45:29 -07001108 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1109 * radix tree based on a tag
1110 * @root: radix tree root
1111 * @results: where the results of the lookup are placed
1112 * @first_index: start the lookup from this key
1113 * @max_items: place up to this many items at *results
1114 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1115 *
1116 * Performs an index-ascending scan of the tree for present items which
1117 * have the tag indexed by @tag set. Places the slots at *@results and
1118 * returns the number of slots which were placed at *@results.
1119 */
1120unsigned int
1121radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
1122 unsigned long first_index, unsigned int max_items,
1123 unsigned int tag)
1124{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001125 struct radix_tree_iter iter;
1126 void **slot;
1127 unsigned int ret = 0;
Nick Piggin47feff22008-07-25 19:45:29 -07001128
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001129 if (unlikely(!max_items))
Nick Piggin47feff22008-07-25 19:45:29 -07001130 return 0;
1131
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001132 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1133 results[ret] = slot;
1134 if (++ret == max_items)
Nick Piggin47feff22008-07-25 19:45:29 -07001135 break;
Nick Piggin47feff22008-07-25 19:45:29 -07001136 }
1137
1138 return ret;
1139}
1140EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1141
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001142#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1143#include <linux/sched.h> /* for cond_resched() */
1144
1145/*
1146 * This linear search is at present only useful to shmem_unuse_inode().
1147 */
1148static unsigned long __locate(struct radix_tree_node *slot, void *item,
1149 unsigned long index, unsigned long *found_index)
1150{
1151 unsigned int shift, height;
1152 unsigned long i;
1153
Johannes Weiner449dd692014-04-03 14:47:56 -07001154 height = slot->path & RADIX_TREE_HEIGHT_MASK;
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001155 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
1156
1157 for ( ; height > 1; height--) {
1158 i = (index >> shift) & RADIX_TREE_MAP_MASK;
1159 for (;;) {
1160 if (slot->slots[i] != NULL)
1161 break;
1162 index &= ~((1UL << shift) - 1);
1163 index += 1UL << shift;
1164 if (index == 0)
1165 goto out; /* 32-bit wraparound */
1166 i++;
1167 if (i == RADIX_TREE_MAP_SIZE)
1168 goto out;
1169 }
1170
1171 shift -= RADIX_TREE_MAP_SHIFT;
1172 slot = rcu_dereference_raw(slot->slots[i]);
1173 if (slot == NULL)
1174 goto out;
1175 }
1176
1177 /* Bottom level: check items */
1178 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
1179 if (slot->slots[i] == item) {
1180 *found_index = index + i;
1181 index = 0;
1182 goto out;
1183 }
1184 }
1185 index += RADIX_TREE_MAP_SIZE;
1186out:
1187 return index;
1188}
1189
1190/**
1191 * radix_tree_locate_item - search through radix tree for item
1192 * @root: radix tree root
1193 * @item: item to be found
1194 *
1195 * Returns index where item was found, or -1 if not found.
1196 * Caller must hold no lock (since this time-consuming function needs
1197 * to be preemptible), and must check afterwards if item is still there.
1198 */
1199unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1200{
1201 struct radix_tree_node *node;
1202 unsigned long max_index;
1203 unsigned long cur_index = 0;
1204 unsigned long found_index = -1;
1205
1206 do {
1207 rcu_read_lock();
1208 node = rcu_dereference_raw(root->rnode);
1209 if (!radix_tree_is_indirect_ptr(node)) {
1210 rcu_read_unlock();
1211 if (node == item)
1212 found_index = 0;
1213 break;
1214 }
1215
1216 node = indirect_to_ptr(node);
Johannes Weiner449dd692014-04-03 14:47:56 -07001217 max_index = radix_tree_maxindex(node->path &
1218 RADIX_TREE_HEIGHT_MASK);
Hugh Dickins5f30fc92014-03-03 15:38:23 -08001219 if (cur_index > max_index) {
1220 rcu_read_unlock();
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001221 break;
Hugh Dickins5f30fc92014-03-03 15:38:23 -08001222 }
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001223
1224 cur_index = __locate(node, item, cur_index, &found_index);
1225 rcu_read_unlock();
1226 cond_resched();
1227 } while (cur_index != 0 && cur_index <= max_index);
1228
1229 return found_index;
1230}
1231#else
1232unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1233{
1234 return -1;
1235}
1236#endif /* CONFIG_SHMEM && CONFIG_SWAP */
Nick Piggin47feff22008-07-25 19:45:29 -07001237
1238/**
Nick Piggina5f51c92006-01-08 01:01:41 -08001239 * radix_tree_shrink - shrink height of a radix tree to minimal
1240 * @root radix tree root
1241 */
1242static inline void radix_tree_shrink(struct radix_tree_root *root)
1243{
1244 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -07001245 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -08001246 struct radix_tree_node *to_free = root->rnode;
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001247 struct radix_tree_node *slot;
Nick Piggina5f51c92006-01-08 01:01:41 -08001248
Nick Pigginc0bc9872007-10-16 01:24:42 -07001249 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
Nick Piggin27d20fd2010-11-11 14:05:19 -08001250 to_free = indirect_to_ptr(to_free);
Nick Pigginc0bc9872007-10-16 01:24:42 -07001251
1252 /*
1253 * The candidate node has more than one child, or its child
1254 * is not at the leftmost slot, we cannot shrink.
1255 */
1256 if (to_free->count != 1)
1257 break;
1258 if (!to_free->slots[0])
1259 break;
1260
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001261 /*
1262 * We don't need rcu_assign_pointer(), since we are simply
Nick Piggin27d20fd2010-11-11 14:05:19 -08001263 * moving the node from one part of the tree to another: if it
1264 * was safe to dereference the old pointer to it
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001265 * (to_free->slots[0]), it will be safe to dereference the new
Nick Piggin27d20fd2010-11-11 14:05:19 -08001266 * one (root->rnode) as far as dependent read barriers go.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001267 */
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001268 slot = to_free->slots[0];
1269 if (root->height > 1) {
1270 slot->parent = NULL;
1271 slot = ptr_to_indirect(slot);
1272 }
1273 root->rnode = slot;
Nick Piggina5f51c92006-01-08 01:01:41 -08001274 root->height--;
Nick Piggin27d20fd2010-11-11 14:05:19 -08001275
1276 /*
1277 * We have a dilemma here. The node's slot[0] must not be
1278 * NULLed in case there are concurrent lookups expecting to
1279 * find the item. However if this was a bottom-level node,
1280 * then it may be subject to the slot pointer being visible
1281 * to callers dereferencing it. If item corresponding to
1282 * slot[0] is subsequently deleted, these callers would expect
1283 * their slot to become empty sooner or later.
1284 *
1285 * For example, lockless pagecache will look up a slot, deref
1286 * the page pointer, and if the page is 0 refcount it means it
1287 * was concurrently deleted from pagecache so try the deref
1288 * again. Fortunately there is already a requirement for logic
1289 * to retry the entire slot lookup -- the indirect pointer
1290 * problem (replacing direct root node with an indirect pointer
1291 * also results in a stale slot). So tag the slot as indirect
1292 * to force callers to retry.
1293 */
1294 if (root->height == 0)
1295 *((unsigned long *)&to_free->slots[0]) |=
1296 RADIX_TREE_INDIRECT_PTR;
1297
Nick Piggina5f51c92006-01-08 01:01:41 -08001298 radix_tree_node_free(to_free);
1299 }
1300}
1301
1302/**
Johannes Weiner139e5612014-04-03 14:47:54 -07001303 * __radix_tree_delete_node - try to free node after clearing a slot
1304 * @root: radix tree root
Johannes Weiner139e5612014-04-03 14:47:54 -07001305 * @node: node containing @index
1306 *
1307 * After clearing the slot at @index in @node from radix tree
1308 * rooted at @root, call this function to attempt freeing the
1309 * node and shrinking the tree.
1310 *
1311 * Returns %true if @node was freed, %false otherwise.
1312 */
Johannes Weiner449dd692014-04-03 14:47:56 -07001313bool __radix_tree_delete_node(struct radix_tree_root *root,
Johannes Weiner139e5612014-04-03 14:47:54 -07001314 struct radix_tree_node *node)
1315{
1316 bool deleted = false;
1317
1318 do {
1319 struct radix_tree_node *parent;
1320
1321 if (node->count) {
1322 if (node == indirect_to_ptr(root->rnode)) {
1323 radix_tree_shrink(root);
1324 if (root->height == 0)
1325 deleted = true;
1326 }
1327 return deleted;
1328 }
1329
1330 parent = node->parent;
1331 if (parent) {
Johannes Weiner449dd692014-04-03 14:47:56 -07001332 unsigned int offset;
Johannes Weiner139e5612014-04-03 14:47:54 -07001333
Johannes Weiner449dd692014-04-03 14:47:56 -07001334 offset = node->path >> RADIX_TREE_HEIGHT_SHIFT;
1335 parent->slots[offset] = NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -07001336 parent->count--;
1337 } else {
1338 root_tag_clear_all(root);
1339 root->height = 0;
1340 root->rnode = NULL;
1341 }
1342
1343 radix_tree_node_free(node);
1344 deleted = true;
1345
1346 node = parent;
1347 } while (node);
1348
1349 return deleted;
1350}
1351
1352/**
Johannes Weiner53c59f22014-04-03 14:47:39 -07001353 * radix_tree_delete_item - delete an item from a radix tree
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 * @root: radix tree root
1355 * @index: index key
Johannes Weiner53c59f22014-04-03 14:47:39 -07001356 * @item: expected item
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 *
Johannes Weiner53c59f22014-04-03 14:47:39 -07001358 * Remove @item at @index from the radix tree rooted at @root.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 *
Johannes Weiner53c59f22014-04-03 14:47:39 -07001360 * Returns the address of the deleted item, or NULL if it was not present
1361 * or the entry at the given @index was not @item.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 */
Johannes Weiner53c59f22014-04-03 14:47:39 -07001363void *radix_tree_delete_item(struct radix_tree_root *root,
1364 unsigned long index, void *item)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365{
Johannes Weiner139e5612014-04-03 14:47:54 -07001366 struct radix_tree_node *node;
1367 unsigned int offset;
1368 void **slot;
1369 void *entry;
Nick Piggind5274262006-01-08 01:01:41 -08001370 int tag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371
Johannes Weiner139e5612014-04-03 14:47:54 -07001372 entry = __radix_tree_lookup(root, index, &node, &slot);
1373 if (!entry)
1374 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375
Johannes Weiner139e5612014-04-03 14:47:54 -07001376 if (item && entry != item)
1377 return NULL;
1378
1379 if (!node) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001380 root_tag_clear_all(root);
1381 root->rnode = NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -07001382 return entry;
Nick Piggin612d6c12006-06-23 02:03:22 -07001383 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384
Johannes Weiner139e5612014-04-03 14:47:54 -07001385 offset = index & RADIX_TREE_MAP_MASK;
Johannes Weiner53c59f22014-04-03 14:47:39 -07001386
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 /*
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001388 * Clear all tags associated with the item to be deleted.
1389 * This way of doing it would be inefficient, but seldom is any set.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001391 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001392 if (tag_get(node, tag, offset))
Nick Piggin612d6c12006-06-23 02:03:22 -07001393 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395
Johannes Weiner139e5612014-04-03 14:47:54 -07001396 node->slots[offset] = NULL;
1397 node->count--;
Nick Piggina5f51c92006-01-08 01:01:41 -08001398
Johannes Weiner449dd692014-04-03 14:47:56 -07001399 __radix_tree_delete_node(root, node);
Christoph Lameter201b6262005-09-06 15:16:46 -07001400
Johannes Weiner139e5612014-04-03 14:47:54 -07001401 return entry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402}
Johannes Weiner53c59f22014-04-03 14:47:39 -07001403EXPORT_SYMBOL(radix_tree_delete_item);
1404
1405/**
1406 * radix_tree_delete - delete an item from a radix tree
1407 * @root: radix tree root
1408 * @index: index key
1409 *
1410 * Remove the item at @index from the radix tree rooted at @root.
1411 *
1412 * Returns the address of the deleted item, or NULL if it was not present.
1413 */
1414void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1415{
1416 return radix_tree_delete_item(root, index, NULL);
1417}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418EXPORT_SYMBOL(radix_tree_delete);
1419
1420/**
1421 * radix_tree_tagged - test whether any items in the tree are tagged
1422 * @root: radix tree root
1423 * @tag: tag to test
1424 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001425int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426{
Nick Piggin612d6c12006-06-23 02:03:22 -07001427 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428}
1429EXPORT_SYMBOL(radix_tree_tagged);
1430
1431static void
Johannes Weiner449dd692014-04-03 14:47:56 -07001432radix_tree_node_ctor(void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433{
Johannes Weiner449dd692014-04-03 14:47:56 -07001434 struct radix_tree_node *node = arg;
1435
1436 memset(node, 0, sizeof(*node));
1437 INIT_LIST_HEAD(&node->private_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438}
1439
1440static __init unsigned long __maxindex(unsigned int height)
1441{
Peter Lund430d2752007-10-16 23:29:35 -07001442 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1443 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444
Peter Lund430d2752007-10-16 23:29:35 -07001445 if (shift < 0)
1446 return ~0UL;
1447 if (shift >= BITS_PER_LONG)
1448 return 0UL;
1449 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450}
1451
1452static __init void radix_tree_init_maxindex(void)
1453{
1454 unsigned int i;
1455
1456 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1457 height_to_maxindex[i] = __maxindex(i);
1458}
1459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460static int radix_tree_callback(struct notifier_block *nfb,
1461 unsigned long action,
1462 void *hcpu)
1463{
1464 int cpu = (long)hcpu;
1465 struct radix_tree_preload *rtp;
1466
1467 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001468 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469 rtp = &per_cpu(radix_tree_preloads, cpu);
1470 while (rtp->nr) {
1471 kmem_cache_free(radix_tree_node_cachep,
1472 rtp->nodes[rtp->nr-1]);
1473 rtp->nodes[rtp->nr-1] = NULL;
1474 rtp->nr--;
1475 }
1476 }
1477 return NOTIFY_OK;
1478}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479
1480void __init radix_tree_init(void)
1481{
1482 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1483 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001484 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1485 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 radix_tree_init_maxindex();
1487 hotcpu_notifier(radix_tree_callback, 0);
1488}