blob: 9599aa72d7a024795b300750e55147a60f58ed19 [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>
30#include <linux/notifier.h>
31#include <linux/cpu.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/string.h>
33#include <linux/bitops.h>
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080034#include <linux/rcupdate.h>
Jan Kara5e4c0d972013-09-11 14:26:05 -070035#include <linux/hardirq.h> /* in_interrupt() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37
Jeff Moyer26fb1582007-10-16 01:24:49 -070038/*
39 * The height_to_maxindex array needs to be one deeper than the maximum
40 * path as height 0 holds only 1 entry.
41 */
42static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44/*
45 * Radix tree node cache.
46 */
Christoph Lametere18b8902006-12-06 20:33:20 -080047static struct kmem_cache *radix_tree_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
49/*
Nick Piggin55368052012-05-29 15:07:34 -070050 * The radix tree is variable-height, so an insert operation not only has
51 * to build the branch to its corresponding item, it also has to build the
52 * branch to existing items if the size has to be increased (by
53 * radix_tree_extend).
54 *
55 * The worst case is a zero height tree with just a single item at index 0,
56 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
57 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
58 * Hence:
59 */
60#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
61
62/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 * Per-cpu pool of preloaded nodes
64 */
65struct radix_tree_preload {
66 int nr;
Nick Piggin55368052012-05-29 15:07:34 -070067 struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070068};
Harvey Harrison8cef7d52009-01-06 14:40:50 -080069static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
Nick Piggin27d20fd2010-11-11 14:05:19 -080071static inline void *ptr_to_indirect(void *ptr)
72{
73 return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
74}
75
76static inline void *indirect_to_ptr(void *ptr)
77{
78 return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
79}
80
Nick Piggin612d6c12006-06-23 02:03:22 -070081static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
82{
83 return root->gfp_mask & __GFP_BITS_MASK;
84}
85
Nick Piggin643b52b2008-06-12 15:21:52 -070086static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
87 int offset)
88{
89 __set_bit(offset, node->tags[tag]);
90}
91
92static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
93 int offset)
94{
95 __clear_bit(offset, node->tags[tag]);
96}
97
98static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
99 int offset)
100{
101 return test_bit(offset, node->tags[tag]);
102}
103
104static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
105{
106 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
107}
108
109static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
110{
111 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
112}
113
114static inline void root_tag_clear_all(struct radix_tree_root *root)
115{
116 root->gfp_mask &= __GFP_BITS_MASK;
117}
118
119static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
120{
121 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
122}
123
124/*
125 * Returns 1 if any slot in the node has this tag set.
126 * Otherwise returns 0.
127 */
128static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
129{
130 int idx;
131 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
132 if (node->tags[tag][idx])
133 return 1;
134 }
135 return 0;
136}
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700137
138/**
139 * radix_tree_find_next_bit - find the next set bit in a memory region
140 *
141 * @addr: The address to base the search on
142 * @size: The bitmap size in bits
143 * @offset: The bitnumber to start searching at
144 *
145 * Unrollable variant of find_next_bit() for constant size arrays.
146 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
147 * Returns next bit offset, or size if nothing found.
148 */
149static __always_inline unsigned long
150radix_tree_find_next_bit(const unsigned long *addr,
151 unsigned long size, unsigned long offset)
152{
153 if (!__builtin_constant_p(size))
154 return find_next_bit(addr, size, offset);
155
156 if (offset < size) {
157 unsigned long tmp;
158
159 addr += offset / BITS_PER_LONG;
160 tmp = *addr >> (offset % BITS_PER_LONG);
161 if (tmp)
162 return __ffs(tmp) + offset;
163 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
164 while (offset < size) {
165 tmp = *++addr;
166 if (tmp)
167 return __ffs(tmp) + offset;
168 offset += BITS_PER_LONG;
169 }
170 }
171 return size;
172}
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174/*
175 * This assumes that the caller has performed appropriate preallocation, and
176 * that the caller has pinned this thread of control to the current CPU.
177 */
178static struct radix_tree_node *
179radix_tree_node_alloc(struct radix_tree_root *root)
180{
Nick Piggine2848a02008-02-04 22:29:10 -0800181 struct radix_tree_node *ret = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700182 gfp_t gfp_mask = root_gfp_mask(root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Jan Kara5e4c0d972013-09-11 14:26:05 -0700184 /*
185 * Preload code isn't irq safe and it doesn't make sence to use
186 * preloading in the interrupt anyway as all the allocations have to
187 * be atomic. So just do normal allocation when in interrupt.
188 */
189 if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 struct radix_tree_preload *rtp;
191
Nick Piggine2848a02008-02-04 22:29:10 -0800192 /*
193 * Provided the caller has preloaded here, we will always
194 * succeed in getting a node here (and never reach
195 * kmem_cache_alloc)
196 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 rtp = &__get_cpu_var(radix_tree_preloads);
198 if (rtp->nr) {
199 ret = rtp->nodes[rtp->nr - 1];
200 rtp->nodes[rtp->nr - 1] = NULL;
201 rtp->nr--;
202 }
203 }
Nick Piggine2848a02008-02-04 22:29:10 -0800204 if (ret == NULL)
Christoph Lameter488514d2008-04-28 02:12:05 -0700205 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Nick Piggine2848a02008-02-04 22:29:10 -0800206
Nick Pigginc0bc9872007-10-16 01:24:42 -0700207 BUG_ON(radix_tree_is_indirect_ptr(ret));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 return ret;
209}
210
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800211static void radix_tree_node_rcu_free(struct rcu_head *head)
212{
213 struct radix_tree_node *node =
214 container_of(head, struct radix_tree_node, rcu_head);
Dave Chinnerb6dd0862010-08-23 10:33:19 +1000215 int i;
Nick Piggin643b52b2008-06-12 15:21:52 -0700216
217 /*
218 * must only free zeroed nodes into the slab. radix_tree_shrink
219 * can leave us with a non-NULL entry in the first slot, so clear
220 * that here to make sure.
221 */
Dave Chinnerb6dd0862010-08-23 10:33:19 +1000222 for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
223 tag_clear(node, i, 0);
224
Nick Piggin643b52b2008-06-12 15:21:52 -0700225 node->slots[0] = NULL;
226 node->count = 0;
227
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800228 kmem_cache_free(radix_tree_node_cachep, node);
229}
230
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231static inline void
232radix_tree_node_free(struct radix_tree_node *node)
233{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800234 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235}
236
237/*
238 * Load up this CPU's radix_tree_node buffer with sufficient objects to
239 * ensure that the addition of a single element in the tree cannot fail. On
240 * success, return zero, with preemption disabled. On error, return -ENOMEM
241 * with preemption not disabled.
David Howellsb34df792009-11-19 18:11:14 +0000242 *
243 * To make use of this facility, the radix tree must be initialised without
244 * __GFP_WAIT being passed to INIT_RADIX_TREE().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 */
Jan Kara5e4c0d972013-09-11 14:26:05 -0700246static int __radix_tree_preload(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247{
248 struct radix_tree_preload *rtp;
249 struct radix_tree_node *node;
250 int ret = -ENOMEM;
251
252 preempt_disable();
253 rtp = &__get_cpu_var(radix_tree_preloads);
254 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
255 preempt_enable();
Christoph Lameter488514d2008-04-28 02:12:05 -0700256 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 if (node == NULL)
258 goto out;
259 preempt_disable();
260 rtp = &__get_cpu_var(radix_tree_preloads);
261 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
262 rtp->nodes[rtp->nr++] = node;
263 else
264 kmem_cache_free(radix_tree_node_cachep, node);
265 }
266 ret = 0;
267out:
268 return ret;
269}
Jan Kara5e4c0d972013-09-11 14:26:05 -0700270
271/*
272 * Load up this CPU's radix_tree_node buffer with sufficient objects to
273 * ensure that the addition of a single element in the tree cannot fail. On
274 * success, return zero, with preemption disabled. On error, return -ENOMEM
275 * with preemption not disabled.
276 *
277 * To make use of this facility, the radix tree must be initialised without
278 * __GFP_WAIT being passed to INIT_RADIX_TREE().
279 */
280int radix_tree_preload(gfp_t gfp_mask)
281{
282 /* Warn on non-sensical use... */
283 WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT));
284 return __radix_tree_preload(gfp_mask);
285}
David Chinnerd7f09232007-07-14 16:05:04 +1000286EXPORT_SYMBOL(radix_tree_preload);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287
Nick Piggin6e954b92006-01-08 01:01:40 -0800288/*
Jan Kara5e4c0d972013-09-11 14:26:05 -0700289 * The same as above function, except we don't guarantee preloading happens.
290 * We do it, if we decide it helps. On success, return zero with preemption
291 * disabled. On error, return -ENOMEM with preemption not disabled.
292 */
293int radix_tree_maybe_preload(gfp_t gfp_mask)
294{
295 if (gfp_mask & __GFP_WAIT)
296 return __radix_tree_preload(gfp_mask);
297 /* Preloading doesn't help anything with this gfp mask, skip it */
298 preempt_disable();
299 return 0;
300}
301EXPORT_SYMBOL(radix_tree_maybe_preload);
302
303/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 * Return the maximum key which can be store into a
305 * radix tree with height HEIGHT.
306 */
307static inline unsigned long radix_tree_maxindex(unsigned int height)
308{
309 return height_to_maxindex[height];
310}
311
312/*
313 * Extend a radix tree so it can store key @index.
314 */
315static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
316{
317 struct radix_tree_node *node;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800318 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 unsigned int height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 int tag;
321
322 /* Figure out what the height should be. */
323 height = root->height + 1;
324 while (index > radix_tree_maxindex(height))
325 height++;
326
327 if (root->rnode == NULL) {
328 root->height = height;
329 goto out;
330 }
331
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 do {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800333 unsigned int newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 if (!(node = radix_tree_node_alloc(root)))
335 return -ENOMEM;
336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 /* Propagate the aggregated tag info into the new root */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800338 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -0700339 if (root_tag_get(root, tag))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 tag_set(node, tag, 0);
341 }
342
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800343 /* Increase the height. */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800344 newheight = root->height+1;
Johannes Weiner449dd692014-04-03 14:47:56 -0700345 BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK);
346 node->path = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 node->count = 1;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800348 node->parent = NULL;
349 slot = root->rnode;
350 if (newheight > 1) {
351 slot = indirect_to_ptr(slot);
352 slot->parent = node;
353 }
354 node->slots[0] = slot;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800355 node = ptr_to_indirect(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800356 rcu_assign_pointer(root->rnode, node);
357 root->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 } while (height > root->height);
359out:
360 return 0;
361}
362
363/**
Johannes Weiner139e5612014-04-03 14:47:54 -0700364 * __radix_tree_create - create a slot in a radix tree
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 * @root: radix tree root
366 * @index: index key
Johannes Weiner139e5612014-04-03 14:47:54 -0700367 * @nodep: returns node
368 * @slotp: returns slot
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 *
Johannes Weiner139e5612014-04-03 14:47:54 -0700370 * Create, if necessary, and return the node and slot for an item
371 * at position @index in the radix tree @root.
372 *
373 * Until there is more than one item in the tree, no nodes are
374 * allocated and @root->rnode is used as a direct slot instead of
375 * pointing to a node, in which case *@nodep will be NULL.
376 *
377 * Returns -ENOMEM, or 0 for success.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 */
Johannes Weiner139e5612014-04-03 14:47:54 -0700379int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
380 struct radix_tree_node **nodep, void ***slotp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381{
Christoph Lameter201b6262005-09-06 15:16:46 -0700382 struct radix_tree_node *node = NULL, *slot;
Johannes Weiner139e5612014-04-03 14:47:54 -0700383 unsigned int height, shift, offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 int error;
385
386 /* Make sure the tree is high enough. */
Nick Piggin612d6c12006-06-23 02:03:22 -0700387 if (index > radix_tree_maxindex(root->height)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 error = radix_tree_extend(root, index);
389 if (error)
390 return error;
391 }
392
Nick Piggin27d20fd2010-11-11 14:05:19 -0800393 slot = indirect_to_ptr(root->rnode);
Nick Pigginc0bc9872007-10-16 01:24:42 -0700394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 height = root->height;
396 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
397
398 offset = 0; /* uninitialised var warning */
Nick Piggin612d6c12006-06-23 02:03:22 -0700399 while (height > 0) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700400 if (slot == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 /* Have to add a child node. */
Christoph Lameter201b6262005-09-06 15:16:46 -0700402 if (!(slot = radix_tree_node_alloc(root)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 return -ENOMEM;
Johannes Weiner449dd692014-04-03 14:47:56 -0700404 slot->path = height;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800405 slot->parent = node;
Christoph Lameter201b6262005-09-06 15:16:46 -0700406 if (node) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800407 rcu_assign_pointer(node->slots[offset], slot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 node->count++;
Johannes Weiner449dd692014-04-03 14:47:56 -0700409 slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT;
Christoph Lameter201b6262005-09-06 15:16:46 -0700410 } else
Nick Piggin27d20fd2010-11-11 14:05:19 -0800411 rcu_assign_pointer(root->rnode, ptr_to_indirect(slot));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 }
413
414 /* Go a level down */
415 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Christoph Lameter201b6262005-09-06 15:16:46 -0700416 node = slot;
417 slot = node->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 shift -= RADIX_TREE_MAP_SHIFT;
419 height--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700420 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421
Johannes Weiner139e5612014-04-03 14:47:54 -0700422 if (nodep)
423 *nodep = node;
424 if (slotp)
425 *slotp = node ? node->slots + offset : (void **)&root->rnode;
426 return 0;
427}
428
429/**
430 * radix_tree_insert - insert into a radix tree
431 * @root: radix tree root
432 * @index: index key
433 * @item: item to insert
434 *
435 * Insert an item into the radix tree at position @index.
436 */
437int radix_tree_insert(struct radix_tree_root *root,
438 unsigned long index, void *item)
439{
440 struct radix_tree_node *node;
441 void **slot;
442 int error;
443
444 BUG_ON(radix_tree_is_indirect_ptr(item));
445
446 error = __radix_tree_create(root, index, &node, &slot);
447 if (error)
448 return error;
449 if (*slot != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 return -EEXIST;
Johannes Weiner139e5612014-04-03 14:47:54 -0700451 rcu_assign_pointer(*slot, item);
Christoph Lameter201b6262005-09-06 15:16:46 -0700452
Nick Piggin612d6c12006-06-23 02:03:22 -0700453 if (node) {
454 node->count++;
Johannes Weiner139e5612014-04-03 14:47:54 -0700455 BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
456 BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
Nick Piggin612d6c12006-06-23 02:03:22 -0700457 } else {
Nick Piggin612d6c12006-06-23 02:03:22 -0700458 BUG_ON(root_tag_get(root, 0));
459 BUG_ON(root_tag_get(root, 1));
460 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 return 0;
463}
464EXPORT_SYMBOL(radix_tree_insert);
465
Johannes Weiner139e5612014-04-03 14:47:54 -0700466/**
467 * __radix_tree_lookup - lookup an item in a radix tree
468 * @root: radix tree root
469 * @index: index key
470 * @nodep: returns node
471 * @slotp: returns slot
472 *
473 * Lookup and return the item at position @index in the radix
474 * tree @root.
475 *
476 * Until there is more than one item in the tree, no nodes are
477 * allocated and @root->rnode is used as a direct slot instead of
478 * pointing to a node, in which case *@nodep will be NULL.
Hans Reisera4331362005-11-07 00:59:29 -0800479 */
Johannes Weiner139e5612014-04-03 14:47:54 -0700480void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
481 struct radix_tree_node **nodep, void ***slotp)
Hans Reisera4331362005-11-07 00:59:29 -0800482{
Johannes Weiner139e5612014-04-03 14:47:54 -0700483 struct radix_tree_node *node, *parent;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800484 unsigned int height, shift;
Johannes Weiner139e5612014-04-03 14:47:54 -0700485 void **slot;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800486
Paul E. McKenney2676a582010-02-22 17:04:54 -0800487 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800488 if (node == NULL)
489 return NULL;
490
Nick Pigginc0bc9872007-10-16 01:24:42 -0700491 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800492 if (index > 0)
493 return NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -0700494
495 if (nodep)
496 *nodep = NULL;
497 if (slotp)
498 *slotp = (void **)&root->rnode;
499 return node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800500 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800501 node = indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800502
Johannes Weiner449dd692014-04-03 14:47:56 -0700503 height = node->path & RADIX_TREE_HEIGHT_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800504 if (index > radix_tree_maxindex(height))
505 return NULL;
506
507 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
508
509 do {
Johannes Weiner139e5612014-04-03 14:47:54 -0700510 parent = node;
511 slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK);
Paul E. McKenney2676a582010-02-22 17:04:54 -0800512 node = rcu_dereference_raw(*slot);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800513 if (node == NULL)
514 return NULL;
515
516 shift -= RADIX_TREE_MAP_SHIFT;
517 height--;
518 } while (height > 0);
519
Johannes Weiner139e5612014-04-03 14:47:54 -0700520 if (nodep)
521 *nodep = parent;
522 if (slotp)
523 *slotp = slot;
524 return node;
Huang Shijieb72b71c2009-06-16 15:33:42 -0700525}
526
527/**
528 * radix_tree_lookup_slot - lookup a slot in a radix tree
529 * @root: radix tree root
530 * @index: index key
531 *
532 * Returns: the slot corresponding to the position @index in the
533 * radix tree @root. This is useful for update-if-exists operations.
534 *
535 * This function can be called under rcu_read_lock iff the slot is not
536 * modified by radix_tree_replace_slot, otherwise it must be called
537 * exclusive from other writers. Any dereference of the slot must be done
538 * using radix_tree_deref_slot.
539 */
540void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
541{
Johannes Weiner139e5612014-04-03 14:47:54 -0700542 void **slot;
543
544 if (!__radix_tree_lookup(root, index, NULL, &slot))
545 return NULL;
546 return slot;
Hans Reisera4331362005-11-07 00:59:29 -0800547}
548EXPORT_SYMBOL(radix_tree_lookup_slot);
549
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550/**
551 * radix_tree_lookup - perform lookup operation on a radix tree
552 * @root: radix tree root
553 * @index: index key
554 *
555 * Lookup the item at the position @index in the radix tree @root.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800556 *
557 * This function can be called under rcu_read_lock, however the caller
558 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
559 * them safely). No RCU barriers are required to access or modify the
560 * returned item, however.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 */
562void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
563{
Johannes Weiner139e5612014-04-03 14:47:54 -0700564 return __radix_tree_lookup(root, index, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565}
566EXPORT_SYMBOL(radix_tree_lookup);
567
568/**
569 * radix_tree_tag_set - set a tag on a radix tree node
570 * @root: radix tree root
571 * @index: index key
572 * @tag: tag index
573 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800574 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
575 * corresponding to @index in the radix tree. From
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 * the root all the way down to the leaf node.
577 *
578 * Returns the address of the tagged item. Setting a tag on a not-present
579 * item is a bug.
580 */
581void *radix_tree_tag_set(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800582 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583{
584 unsigned int height, shift;
Christoph Lameter201b6262005-09-06 15:16:46 -0700585 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586
587 height = root->height;
Peter Zijlstra4c91c362006-06-23 02:03:25 -0700588 BUG_ON(index > radix_tree_maxindex(height));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589
Nick Piggin27d20fd2010-11-11 14:05:19 -0800590 slot = indirect_to_ptr(root->rnode);
Nick Piggin612d6c12006-06-23 02:03:22 -0700591 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
593 while (height > 0) {
594 int offset;
595
596 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggind5274262006-01-08 01:01:41 -0800597 if (!tag_get(slot, tag, offset))
598 tag_set(slot, tag, offset);
Christoph Lameter201b6262005-09-06 15:16:46 -0700599 slot = slot->slots[offset];
600 BUG_ON(slot == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 shift -= RADIX_TREE_MAP_SHIFT;
602 height--;
603 }
604
Nick Piggin612d6c12006-06-23 02:03:22 -0700605 /* set the root's tag bit */
606 if (slot && !root_tag_get(root, tag))
607 root_tag_set(root, tag);
608
Christoph Lameter201b6262005-09-06 15:16:46 -0700609 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610}
611EXPORT_SYMBOL(radix_tree_tag_set);
612
613/**
614 * radix_tree_tag_clear - clear a tag on a radix tree node
615 * @root: radix tree root
616 * @index: index key
617 * @tag: tag index
618 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800619 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
620 * corresponding to @index in the radix tree. If
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 * this causes the leaf node to have no tags set then clear the tag in the
622 * next-to-leaf node, etc.
623 *
624 * Returns the address of the tagged item on success, else NULL. ie:
625 * has the same return value and semantics as radix_tree_lookup().
626 */
627void *radix_tree_tag_clear(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800628 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629{
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800630 struct radix_tree_node *node = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700631 struct radix_tree_node *slot = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 unsigned int height, shift;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800633 int uninitialized_var(offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634
635 height = root->height;
636 if (index > radix_tree_maxindex(height))
637 goto out;
638
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800639 shift = height * RADIX_TREE_MAP_SHIFT;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800640 slot = indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800642 while (shift) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700643 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 goto out;
645
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646 shift -= RADIX_TREE_MAP_SHIFT;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800647 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
648 node = slot;
649 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 }
651
Nick Piggin612d6c12006-06-23 02:03:22 -0700652 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 goto out;
654
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800655 while (node) {
656 if (!tag_get(node, tag, offset))
Nick Piggind5274262006-01-08 01:01:41 -0800657 goto out;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800658 tag_clear(node, tag, offset);
659 if (any_tag_set(node, tag))
Nick Piggin6e954b92006-01-08 01:01:40 -0800660 goto out;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800661
662 index >>= RADIX_TREE_MAP_SHIFT;
663 offset = index & RADIX_TREE_MAP_MASK;
664 node = node->parent;
Nick Piggin612d6c12006-06-23 02:03:22 -0700665 }
666
667 /* clear the root's tag bit */
668 if (root_tag_get(root, tag))
669 root_tag_clear(root, tag);
670
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671out:
Nick Piggin612d6c12006-06-23 02:03:22 -0700672 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673}
674EXPORT_SYMBOL(radix_tree_tag_clear);
675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676/**
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700677 * radix_tree_tag_get - get a tag on a radix tree node
678 * @root: radix tree root
679 * @index: index key
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800680 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 *
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700682 * Return values:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 *
Nick Piggin612d6c12006-06-23 02:03:22 -0700684 * 0: tag not present or not set
685 * 1: tag set
David Howellsce826532010-04-06 22:36:20 +0100686 *
687 * Note that the return value of this function may not be relied on, even if
688 * the RCU lock is held, unless tag modification and node deletion are excluded
689 * from concurrency.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 */
691int radix_tree_tag_get(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800692 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693{
694 unsigned int height, shift;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800695 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696
Nick Piggin612d6c12006-06-23 02:03:22 -0700697 /* check the root's tag bit */
698 if (!root_tag_get(root, tag))
699 return 0;
700
Paul E. McKenney2676a582010-02-22 17:04:54 -0800701 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800702 if (node == NULL)
703 return 0;
704
Nick Pigginc0bc9872007-10-16 01:24:42 -0700705 if (!radix_tree_is_indirect_ptr(node))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800706 return (index == 0);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800707 node = indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800708
Johannes Weiner449dd692014-04-03 14:47:56 -0700709 height = node->path & RADIX_TREE_HEIGHT_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800710 if (index > radix_tree_maxindex(height))
711 return 0;
Nick Piggin612d6c12006-06-23 02:03:22 -0700712
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714
715 for ( ; ; ) {
716 int offset;
717
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800718 if (node == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 return 0;
720
721 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800722 if (!tag_get(node, tag, offset))
Hugh Dickins3fa36ac2011-10-31 17:07:02 -0700723 return 0;
David Howellsce826532010-04-06 22:36:20 +0100724 if (height == 1)
Hugh Dickins3fa36ac2011-10-31 17:07:02 -0700725 return 1;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800726 node = rcu_dereference_raw(node->slots[offset]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 shift -= RADIX_TREE_MAP_SHIFT;
728 height--;
729 }
730}
731EXPORT_SYMBOL(radix_tree_tag_get);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700733/**
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700734 * radix_tree_next_chunk - find next chunk of slots for iteration
735 *
736 * @root: radix tree root
737 * @iter: iterator state
738 * @flags: RADIX_TREE_ITER_* flags and tag index
739 * Returns: pointer to chunk first slot, or NULL if iteration is over
740 */
741void **radix_tree_next_chunk(struct radix_tree_root *root,
742 struct radix_tree_iter *iter, unsigned flags)
743{
744 unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
745 struct radix_tree_node *rnode, *node;
Johannes Weiner449dd692014-04-03 14:47:56 -0700746 unsigned long index, offset, height;
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700747
748 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
749 return NULL;
750
751 /*
752 * Catch next_index overflow after ~0UL. iter->index never overflows
753 * during iterating; it can be zero only at the beginning.
754 * And we cannot overflow iter->next_index in a single step,
755 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
Konstantin Khlebnikovfffaee32012-06-05 21:36:33 +0400756 *
757 * This condition also used by radix_tree_next_slot() to stop
758 * contiguous iterating, and forbid swithing to the next chunk.
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700759 */
760 index = iter->next_index;
761 if (!index && iter->index)
762 return NULL;
763
764 rnode = rcu_dereference_raw(root->rnode);
765 if (radix_tree_is_indirect_ptr(rnode)) {
766 rnode = indirect_to_ptr(rnode);
767 } else if (rnode && !index) {
768 /* Single-slot tree */
769 iter->index = 0;
770 iter->next_index = 1;
771 iter->tags = 1;
772 return (void **)&root->rnode;
773 } else
774 return NULL;
775
776restart:
Johannes Weiner449dd692014-04-03 14:47:56 -0700777 height = rnode->path & RADIX_TREE_HEIGHT_MASK;
778 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Konstantin Khlebnikov78c1d782012-03-28 14:42:53 -0700779 offset = index >> shift;
780
781 /* Index outside of the tree */
782 if (offset >= RADIX_TREE_MAP_SIZE)
783 return NULL;
784
785 node = rnode;
786 while (1) {
787 if ((flags & RADIX_TREE_ITER_TAGGED) ?
788 !test_bit(offset, node->tags[tag]) :
789 !node->slots[offset]) {
790 /* Hole detected */
791 if (flags & RADIX_TREE_ITER_CONTIG)
792 return NULL;
793
794 if (flags & RADIX_TREE_ITER_TAGGED)
795 offset = radix_tree_find_next_bit(
796 node->tags[tag],
797 RADIX_TREE_MAP_SIZE,
798 offset + 1);
799 else
800 while (++offset < RADIX_TREE_MAP_SIZE) {
801 if (node->slots[offset])
802 break;
803 }
804 index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
805 index += offset << shift;
806 /* Overflow after ~0UL */
807 if (!index)
808 return NULL;
809 if (offset == RADIX_TREE_MAP_SIZE)
810 goto restart;
811 }
812
813 /* This is leaf-node */
814 if (!shift)
815 break;
816
817 node = rcu_dereference_raw(node->slots[offset]);
818 if (node == NULL)
819 goto restart;
820 shift -= RADIX_TREE_MAP_SHIFT;
821 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
822 }
823
824 /* Update the iterator state */
825 iter->index = index;
826 iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1;
827
828 /* Construct iter->tags bit-mask from node->tags[tag] array */
829 if (flags & RADIX_TREE_ITER_TAGGED) {
830 unsigned tag_long, tag_bit;
831
832 tag_long = offset / BITS_PER_LONG;
833 tag_bit = offset % BITS_PER_LONG;
834 iter->tags = node->tags[tag][tag_long] >> tag_bit;
835 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
836 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
837 /* Pick tags from next element */
838 if (tag_bit)
839 iter->tags |= node->tags[tag][tag_long + 1] <<
840 (BITS_PER_LONG - tag_bit);
841 /* Clip chunk size, here only BITS_PER_LONG tags */
842 iter->next_index = index + BITS_PER_LONG;
843 }
844 }
845
846 return node->slots + offset;
847}
848EXPORT_SYMBOL(radix_tree_next_chunk);
849
850/**
Jan Karaebf8aa42010-08-09 17:19:11 -0700851 * radix_tree_range_tag_if_tagged - for each item in given range set given
852 * tag if item has another tag set
853 * @root: radix tree root
854 * @first_indexp: pointer to a starting index of a range to scan
855 * @last_index: last index of a range to scan
856 * @nr_to_tag: maximum number items to tag
857 * @iftag: tag index to test
858 * @settag: tag index to set if tested tag is set
859 *
860 * This function scans range of radix tree from first_index to last_index
861 * (inclusive). For each item in the range if iftag is set, the function sets
862 * also settag. The function stops either after tagging nr_to_tag items or
863 * after reaching last_index.
864 *
Dave Chinner144dcfc2010-08-23 10:33:53 +1000865 * The tags must be set from the leaf level only and propagated back up the
866 * path to the root. We must do this so that we resolve the full path before
867 * setting any tags on intermediate nodes. If we set tags as we descend, then
868 * we can get to the leaf node and find that the index that has the iftag
869 * set is outside the range we are scanning. This reults in dangling tags and
870 * can lead to problems with later tag operations (e.g. livelocks on lookups).
871 *
Jan Karaebf8aa42010-08-09 17:19:11 -0700872 * The function returns number of leaves where the tag was set and sets
873 * *first_indexp to the first unscanned index.
Jan Karad5ed3a42010-08-19 14:13:33 -0700874 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
875 * be prepared to handle that.
Jan Karaebf8aa42010-08-09 17:19:11 -0700876 */
877unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
878 unsigned long *first_indexp, unsigned long last_index,
879 unsigned long nr_to_tag,
880 unsigned int iftag, unsigned int settag)
881{
Dave Chinner144dcfc2010-08-23 10:33:53 +1000882 unsigned int height = root->height;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800883 struct radix_tree_node *node = NULL;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000884 struct radix_tree_node *slot;
885 unsigned int shift;
886 unsigned long tagged = 0;
887 unsigned long index = *first_indexp;
Jan Karaebf8aa42010-08-09 17:19:11 -0700888
889 last_index = min(last_index, radix_tree_maxindex(height));
890 if (index > last_index)
891 return 0;
892 if (!nr_to_tag)
893 return 0;
894 if (!root_tag_get(root, iftag)) {
895 *first_indexp = last_index + 1;
896 return 0;
897 }
898 if (height == 0) {
899 *first_indexp = last_index + 1;
900 root_tag_set(root, settag);
901 return 1;
902 }
903
904 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800905 slot = indirect_to_ptr(root->rnode);
Jan Karaebf8aa42010-08-09 17:19:11 -0700906
907 for (;;) {
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800908 unsigned long upindex;
Jan Karaebf8aa42010-08-09 17:19:11 -0700909 int offset;
910
911 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
912 if (!slot->slots[offset])
913 goto next;
914 if (!tag_get(slot, iftag, offset))
915 goto next;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800916 if (shift) {
Dave Chinner144dcfc2010-08-23 10:33:53 +1000917 /* Go down one level */
Dave Chinner144dcfc2010-08-23 10:33:53 +1000918 shift -= RADIX_TREE_MAP_SHIFT;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800919 node = slot;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000920 slot = slot->slots[offset];
921 continue;
Jan Karaebf8aa42010-08-09 17:19:11 -0700922 }
Dave Chinner144dcfc2010-08-23 10:33:53 +1000923
924 /* tag the leaf */
925 tagged++;
926 tag_set(slot, settag, offset);
927
928 /* walk back up the path tagging interior nodes */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800929 upindex = index;
930 while (node) {
931 upindex >>= RADIX_TREE_MAP_SHIFT;
932 offset = upindex & RADIX_TREE_MAP_MASK;
933
Dave Chinner144dcfc2010-08-23 10:33:53 +1000934 /* stop if we find a node with the tag already set */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800935 if (tag_get(node, settag, offset))
Dave Chinner144dcfc2010-08-23 10:33:53 +1000936 break;
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800937 tag_set(node, settag, offset);
938 node = node->parent;
Dave Chinner144dcfc2010-08-23 10:33:53 +1000939 }
940
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800941 /*
942 * Small optimization: now clear that node pointer.
943 * Since all of this slot's ancestors now have the tag set
944 * from setting it above, we have no further need to walk
945 * back up the tree setting tags, until we update slot to
946 * point to another radix_tree_node.
947 */
948 node = NULL;
949
Jan Karaebf8aa42010-08-09 17:19:11 -0700950next:
951 /* Go to next item at level determined by 'shift' */
952 index = ((index >> shift) + 1) << shift;
Jan Karad5ed3a42010-08-19 14:13:33 -0700953 /* Overflow can happen when last_index is ~0UL... */
954 if (index > last_index || !index)
Jan Karaebf8aa42010-08-09 17:19:11 -0700955 break;
956 if (tagged >= nr_to_tag)
957 break;
958 while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
959 /*
960 * We've fully scanned this node. Go up. Because
961 * last_index is guaranteed to be in the tree, what
962 * we do below cannot wander astray.
963 */
Hugh Dickinse2bdb932012-01-12 17:20:41 -0800964 slot = slot->parent;
Jan Karaebf8aa42010-08-09 17:19:11 -0700965 shift += RADIX_TREE_MAP_SHIFT;
966 }
967 }
968 /*
Toshiyuki Okajimaac15ee62011-01-25 15:07:32 -0800969 * We need not to tag the root tag if there is no tag which is set with
970 * settag within the range from *first_indexp to last_index.
Jan Karaebf8aa42010-08-09 17:19:11 -0700971 */
Toshiyuki Okajimaac15ee62011-01-25 15:07:32 -0800972 if (tagged > 0)
973 root_tag_set(root, settag);
Jan Karaebf8aa42010-08-09 17:19:11 -0700974 *first_indexp = index;
975
976 return tagged;
977}
978EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980/**
981 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
982 * @root: radix tree root
983 * @results: where the results of the lookup are placed
984 * @first_index: start the lookup from this key
985 * @max_items: place up to this many items at *results
986 *
987 * Performs an index-ascending scan of the tree for present items. Places
988 * them at *@results and returns the number of items which were placed at
989 * *@results.
990 *
991 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800992 *
993 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
994 * rcu_read_lock. In this case, rather than the returned results being
995 * an atomic snapshot of the tree at a single point in time, the semantics
996 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
997 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 */
999unsigned int
1000radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
1001 unsigned long first_index, unsigned int max_items)
1002{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001003 struct radix_tree_iter iter;
1004 void **slot;
1005 unsigned int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001007 if (unlikely(!max_items))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001008 return 0;
1009
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001010 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1011 results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
1012 if (!results[ret])
1013 continue;
1014 if (++ret == max_items)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001017
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 return ret;
1019}
1020EXPORT_SYMBOL(radix_tree_gang_lookup);
1021
Nick Piggin47feff22008-07-25 19:45:29 -07001022/**
1023 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1024 * @root: radix tree root
1025 * @results: where the results of the lookup are placed
Hugh Dickins63286502011-08-03 16:21:18 -07001026 * @indices: where their indices should be placed (but usually NULL)
Nick Piggin47feff22008-07-25 19:45:29 -07001027 * @first_index: start the lookup from this key
1028 * @max_items: place up to this many items at *results
1029 *
1030 * Performs an index-ascending scan of the tree for present items. Places
1031 * their slots at *@results and returns the number of items which were
1032 * placed at *@results.
1033 *
1034 * The implementation is naive.
1035 *
1036 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1037 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1038 * protection, radix_tree_deref_slot may fail requiring a retry.
1039 */
1040unsigned int
Hugh Dickins63286502011-08-03 16:21:18 -07001041radix_tree_gang_lookup_slot(struct radix_tree_root *root,
1042 void ***results, unsigned long *indices,
Nick Piggin47feff22008-07-25 19:45:29 -07001043 unsigned long first_index, unsigned int max_items)
1044{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001045 struct radix_tree_iter iter;
1046 void **slot;
1047 unsigned int ret = 0;
Nick Piggin47feff22008-07-25 19:45:29 -07001048
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001049 if (unlikely(!max_items))
Nick Piggin47feff22008-07-25 19:45:29 -07001050 return 0;
1051
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001052 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1053 results[ret] = slot;
Hugh Dickins63286502011-08-03 16:21:18 -07001054 if (indices)
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001055 indices[ret] = iter.index;
1056 if (++ret == max_items)
Nick Piggin47feff22008-07-25 19:45:29 -07001057 break;
Nick Piggin47feff22008-07-25 19:45:29 -07001058 }
1059
1060 return ret;
1061}
1062EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
1063
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064/**
1065 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1066 * based on a tag
1067 * @root: radix tree root
1068 * @results: where the results of the lookup are placed
1069 * @first_index: start the lookup from this key
1070 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001071 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 *
1073 * Performs an index-ascending scan of the tree for present items which
1074 * have the tag indexed by @tag set. Places the items at *@results and
1075 * returns the number of items which were placed at *@results.
1076 */
1077unsigned int
1078radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001079 unsigned long first_index, unsigned int max_items,
1080 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001082 struct radix_tree_iter iter;
1083 void **slot;
1084 unsigned int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001086 if (unlikely(!max_items))
Nick Piggin612d6c12006-06-23 02:03:22 -07001087 return 0;
1088
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001089 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1090 results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
1091 if (!results[ret])
1092 continue;
1093 if (++ret == max_items)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 return ret;
1098}
1099EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1100
1101/**
Nick Piggin47feff22008-07-25 19:45:29 -07001102 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1103 * radix tree based on a tag
1104 * @root: radix tree root
1105 * @results: where the results of the lookup are placed
1106 * @first_index: start the lookup from this key
1107 * @max_items: place up to this many items at *results
1108 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1109 *
1110 * Performs an index-ascending scan of the tree for present items which
1111 * have the tag indexed by @tag set. Places the slots at *@results and
1112 * returns the number of slots which were placed at *@results.
1113 */
1114unsigned int
1115radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
1116 unsigned long first_index, unsigned int max_items,
1117 unsigned int tag)
1118{
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001119 struct radix_tree_iter iter;
1120 void **slot;
1121 unsigned int ret = 0;
Nick Piggin47feff22008-07-25 19:45:29 -07001122
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001123 if (unlikely(!max_items))
Nick Piggin47feff22008-07-25 19:45:29 -07001124 return 0;
1125
Konstantin Khlebnikovcebbd292012-03-28 14:42:53 -07001126 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1127 results[ret] = slot;
1128 if (++ret == max_items)
Nick Piggin47feff22008-07-25 19:45:29 -07001129 break;
Nick Piggin47feff22008-07-25 19:45:29 -07001130 }
1131
1132 return ret;
1133}
1134EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1135
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001136#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1137#include <linux/sched.h> /* for cond_resched() */
1138
1139/*
1140 * This linear search is at present only useful to shmem_unuse_inode().
1141 */
1142static unsigned long __locate(struct radix_tree_node *slot, void *item,
1143 unsigned long index, unsigned long *found_index)
1144{
1145 unsigned int shift, height;
1146 unsigned long i;
1147
Johannes Weiner449dd692014-04-03 14:47:56 -07001148 height = slot->path & RADIX_TREE_HEIGHT_MASK;
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001149 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
1150
1151 for ( ; height > 1; height--) {
1152 i = (index >> shift) & RADIX_TREE_MAP_MASK;
1153 for (;;) {
1154 if (slot->slots[i] != NULL)
1155 break;
1156 index &= ~((1UL << shift) - 1);
1157 index += 1UL << shift;
1158 if (index == 0)
1159 goto out; /* 32-bit wraparound */
1160 i++;
1161 if (i == RADIX_TREE_MAP_SIZE)
1162 goto out;
1163 }
1164
1165 shift -= RADIX_TREE_MAP_SHIFT;
1166 slot = rcu_dereference_raw(slot->slots[i]);
1167 if (slot == NULL)
1168 goto out;
1169 }
1170
1171 /* Bottom level: check items */
1172 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
1173 if (slot->slots[i] == item) {
1174 *found_index = index + i;
1175 index = 0;
1176 goto out;
1177 }
1178 }
1179 index += RADIX_TREE_MAP_SIZE;
1180out:
1181 return index;
1182}
1183
1184/**
1185 * radix_tree_locate_item - search through radix tree for item
1186 * @root: radix tree root
1187 * @item: item to be found
1188 *
1189 * Returns index where item was found, or -1 if not found.
1190 * Caller must hold no lock (since this time-consuming function needs
1191 * to be preemptible), and must check afterwards if item is still there.
1192 */
1193unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1194{
1195 struct radix_tree_node *node;
1196 unsigned long max_index;
1197 unsigned long cur_index = 0;
1198 unsigned long found_index = -1;
1199
1200 do {
1201 rcu_read_lock();
1202 node = rcu_dereference_raw(root->rnode);
1203 if (!radix_tree_is_indirect_ptr(node)) {
1204 rcu_read_unlock();
1205 if (node == item)
1206 found_index = 0;
1207 break;
1208 }
1209
1210 node = indirect_to_ptr(node);
Johannes Weiner449dd692014-04-03 14:47:56 -07001211 max_index = radix_tree_maxindex(node->path &
1212 RADIX_TREE_HEIGHT_MASK);
Hugh Dickins5f30fc92014-03-03 15:38:23 -08001213 if (cur_index > max_index) {
1214 rcu_read_unlock();
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001215 break;
Hugh Dickins5f30fc92014-03-03 15:38:23 -08001216 }
Hugh Dickinse504f3f2011-08-03 16:21:27 -07001217
1218 cur_index = __locate(node, item, cur_index, &found_index);
1219 rcu_read_unlock();
1220 cond_resched();
1221 } while (cur_index != 0 && cur_index <= max_index);
1222
1223 return found_index;
1224}
1225#else
1226unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1227{
1228 return -1;
1229}
1230#endif /* CONFIG_SHMEM && CONFIG_SWAP */
Nick Piggin47feff22008-07-25 19:45:29 -07001231
1232/**
Nick Piggina5f51c92006-01-08 01:01:41 -08001233 * radix_tree_shrink - shrink height of a radix tree to minimal
1234 * @root radix tree root
1235 */
1236static inline void radix_tree_shrink(struct radix_tree_root *root)
1237{
1238 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -07001239 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -08001240 struct radix_tree_node *to_free = root->rnode;
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001241 struct radix_tree_node *slot;
Nick Piggina5f51c92006-01-08 01:01:41 -08001242
Nick Pigginc0bc9872007-10-16 01:24:42 -07001243 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
Nick Piggin27d20fd2010-11-11 14:05:19 -08001244 to_free = indirect_to_ptr(to_free);
Nick Pigginc0bc9872007-10-16 01:24:42 -07001245
1246 /*
1247 * The candidate node has more than one child, or its child
1248 * is not at the leftmost slot, we cannot shrink.
1249 */
1250 if (to_free->count != 1)
1251 break;
1252 if (!to_free->slots[0])
1253 break;
1254
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001255 /*
1256 * We don't need rcu_assign_pointer(), since we are simply
Nick Piggin27d20fd2010-11-11 14:05:19 -08001257 * moving the node from one part of the tree to another: if it
1258 * was safe to dereference the old pointer to it
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001259 * (to_free->slots[0]), it will be safe to dereference the new
Nick Piggin27d20fd2010-11-11 14:05:19 -08001260 * one (root->rnode) as far as dependent read barriers go.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001261 */
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001262 slot = to_free->slots[0];
1263 if (root->height > 1) {
1264 slot->parent = NULL;
1265 slot = ptr_to_indirect(slot);
1266 }
1267 root->rnode = slot;
Nick Piggina5f51c92006-01-08 01:01:41 -08001268 root->height--;
Nick Piggin27d20fd2010-11-11 14:05:19 -08001269
1270 /*
1271 * We have a dilemma here. The node's slot[0] must not be
1272 * NULLed in case there are concurrent lookups expecting to
1273 * find the item. However if this was a bottom-level node,
1274 * then it may be subject to the slot pointer being visible
1275 * to callers dereferencing it. If item corresponding to
1276 * slot[0] is subsequently deleted, these callers would expect
1277 * their slot to become empty sooner or later.
1278 *
1279 * For example, lockless pagecache will look up a slot, deref
1280 * the page pointer, and if the page is 0 refcount it means it
1281 * was concurrently deleted from pagecache so try the deref
1282 * again. Fortunately there is already a requirement for logic
1283 * to retry the entire slot lookup -- the indirect pointer
1284 * problem (replacing direct root node with an indirect pointer
1285 * also results in a stale slot). So tag the slot as indirect
1286 * to force callers to retry.
1287 */
1288 if (root->height == 0)
1289 *((unsigned long *)&to_free->slots[0]) |=
1290 RADIX_TREE_INDIRECT_PTR;
1291
Nick Piggina5f51c92006-01-08 01:01:41 -08001292 radix_tree_node_free(to_free);
1293 }
1294}
1295
1296/**
Johannes Weiner139e5612014-04-03 14:47:54 -07001297 * __radix_tree_delete_node - try to free node after clearing a slot
1298 * @root: radix tree root
1299 * @index: index key
1300 * @node: node containing @index
1301 *
1302 * After clearing the slot at @index in @node from radix tree
1303 * rooted at @root, call this function to attempt freeing the
1304 * node and shrinking the tree.
1305 *
1306 * Returns %true if @node was freed, %false otherwise.
1307 */
Johannes Weiner449dd692014-04-03 14:47:56 -07001308bool __radix_tree_delete_node(struct radix_tree_root *root,
Johannes Weiner139e5612014-04-03 14:47:54 -07001309 struct radix_tree_node *node)
1310{
1311 bool deleted = false;
1312
1313 do {
1314 struct radix_tree_node *parent;
1315
1316 if (node->count) {
1317 if (node == indirect_to_ptr(root->rnode)) {
1318 radix_tree_shrink(root);
1319 if (root->height == 0)
1320 deleted = true;
1321 }
1322 return deleted;
1323 }
1324
1325 parent = node->parent;
1326 if (parent) {
Johannes Weiner449dd692014-04-03 14:47:56 -07001327 unsigned int offset;
Johannes Weiner139e5612014-04-03 14:47:54 -07001328
Johannes Weiner449dd692014-04-03 14:47:56 -07001329 offset = node->path >> RADIX_TREE_HEIGHT_SHIFT;
1330 parent->slots[offset] = NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -07001331 parent->count--;
1332 } else {
1333 root_tag_clear_all(root);
1334 root->height = 0;
1335 root->rnode = NULL;
1336 }
1337
1338 radix_tree_node_free(node);
1339 deleted = true;
1340
1341 node = parent;
1342 } while (node);
1343
1344 return deleted;
1345}
1346
1347/**
Johannes Weiner53c59f22014-04-03 14:47:39 -07001348 * radix_tree_delete_item - delete an item from a radix tree
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 * @root: radix tree root
1350 * @index: index key
Johannes Weiner53c59f22014-04-03 14:47:39 -07001351 * @item: expected item
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 *
Johannes Weiner53c59f22014-04-03 14:47:39 -07001353 * Remove @item at @index from the radix tree rooted at @root.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 *
Johannes Weiner53c59f22014-04-03 14:47:39 -07001355 * Returns the address of the deleted item, or NULL if it was not present
1356 * or the entry at the given @index was not @item.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 */
Johannes Weiner53c59f22014-04-03 14:47:39 -07001358void *radix_tree_delete_item(struct radix_tree_root *root,
1359 unsigned long index, void *item)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360{
Johannes Weiner139e5612014-04-03 14:47:54 -07001361 struct radix_tree_node *node;
1362 unsigned int offset;
1363 void **slot;
1364 void *entry;
Nick Piggind5274262006-01-08 01:01:41 -08001365 int tag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Johannes Weiner139e5612014-04-03 14:47:54 -07001367 entry = __radix_tree_lookup(root, index, &node, &slot);
1368 if (!entry)
1369 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370
Johannes Weiner139e5612014-04-03 14:47:54 -07001371 if (item && entry != item)
1372 return NULL;
1373
1374 if (!node) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001375 root_tag_clear_all(root);
1376 root->rnode = NULL;
Johannes Weiner139e5612014-04-03 14:47:54 -07001377 return entry;
Nick Piggin612d6c12006-06-23 02:03:22 -07001378 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
Johannes Weiner139e5612014-04-03 14:47:54 -07001380 offset = index & RADIX_TREE_MAP_MASK;
Johannes Weiner53c59f22014-04-03 14:47:39 -07001381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 /*
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001383 * Clear all tags associated with the item to be deleted.
1384 * This way of doing it would be inefficient, but seldom is any set.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001386 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Hugh Dickinse2bdb932012-01-12 17:20:41 -08001387 if (tag_get(node, tag, offset))
Nick Piggin612d6c12006-06-23 02:03:22 -07001388 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001389 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
Johannes Weiner139e5612014-04-03 14:47:54 -07001391 node->slots[offset] = NULL;
1392 node->count--;
Nick Piggina5f51c92006-01-08 01:01:41 -08001393
Johannes Weiner449dd692014-04-03 14:47:56 -07001394 __radix_tree_delete_node(root, node);
Christoph Lameter201b6262005-09-06 15:16:46 -07001395
Johannes Weiner139e5612014-04-03 14:47:54 -07001396 return entry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397}
Johannes Weiner53c59f22014-04-03 14:47:39 -07001398EXPORT_SYMBOL(radix_tree_delete_item);
1399
1400/**
1401 * radix_tree_delete - delete an item from a radix tree
1402 * @root: radix tree root
1403 * @index: index key
1404 *
1405 * Remove the item at @index from the radix tree rooted at @root.
1406 *
1407 * Returns the address of the deleted item, or NULL if it was not present.
1408 */
1409void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1410{
1411 return radix_tree_delete_item(root, index, NULL);
1412}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413EXPORT_SYMBOL(radix_tree_delete);
1414
1415/**
1416 * radix_tree_tagged - test whether any items in the tree are tagged
1417 * @root: radix tree root
1418 * @tag: tag to test
1419 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001420int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421{
Nick Piggin612d6c12006-06-23 02:03:22 -07001422 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423}
1424EXPORT_SYMBOL(radix_tree_tagged);
1425
1426static void
Johannes Weiner449dd692014-04-03 14:47:56 -07001427radix_tree_node_ctor(void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428{
Johannes Weiner449dd692014-04-03 14:47:56 -07001429 struct radix_tree_node *node = arg;
1430
1431 memset(node, 0, sizeof(*node));
1432 INIT_LIST_HEAD(&node->private_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433}
1434
1435static __init unsigned long __maxindex(unsigned int height)
1436{
Peter Lund430d2752007-10-16 23:29:35 -07001437 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1438 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439
Peter Lund430d2752007-10-16 23:29:35 -07001440 if (shift < 0)
1441 return ~0UL;
1442 if (shift >= BITS_PER_LONG)
1443 return 0UL;
1444 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445}
1446
1447static __init void radix_tree_init_maxindex(void)
1448{
1449 unsigned int i;
1450
1451 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1452 height_to_maxindex[i] = __maxindex(i);
1453}
1454
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455static int radix_tree_callback(struct notifier_block *nfb,
1456 unsigned long action,
1457 void *hcpu)
1458{
1459 int cpu = (long)hcpu;
1460 struct radix_tree_preload *rtp;
1461
1462 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001463 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 rtp = &per_cpu(radix_tree_preloads, cpu);
1465 while (rtp->nr) {
1466 kmem_cache_free(radix_tree_node_cachep,
1467 rtp->nodes[rtp->nr-1]);
1468 rtp->nodes[rtp->nr-1] = NULL;
1469 rtp->nr--;
1470 }
1471 }
1472 return NOTIFY_OK;
1473}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474
1475void __init radix_tree_init(void)
1476{
1477 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1478 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001479 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1480 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 radix_tree_init_maxindex();
1482 hotcpu_notifier(radix_tree_callback, 0);
1483}