blob: 05da38bcc2986c296726981483b05dfc5b12109e [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
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2, or (at
10 * your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <linux/errno.h>
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/radix-tree.h>
27#include <linux/percpu.h>
28#include <linux/slab.h>
29#include <linux/notifier.h>
30#include <linux/cpu.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/string.h>
32#include <linux/bitops.h>
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080033#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35
36#ifdef __KERNEL__
Nick Piggincfd9b7d2006-06-23 02:03:22 -070037#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#else
39#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
40#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
43#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
44
45#define RADIX_TREE_TAG_LONGS \
46 ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
47
48struct radix_tree_node {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080049 unsigned int height; /* Height from the bottom */
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 unsigned int count;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080051 struct rcu_head rcu_head;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 void *slots[RADIX_TREE_MAP_SIZE];
Jonathan Corbetdaff89f2006-03-25 03:08:05 -080053 unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
Linus Torvalds1da177e2005-04-16 15:20:36 -070054};
55
56struct radix_tree_path {
Christoph Lameter201b6262005-09-06 15:16:46 -070057 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 int offset;
59};
60
61#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
Jeff Moyer26fb1582007-10-16 01:24:49 -070062#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
63 RADIX_TREE_MAP_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
Jeff Moyer26fb1582007-10-16 01:24:49 -070065/*
66 * The height_to_maxindex array needs to be one deeper than the maximum
67 * path as height 0 holds only 1 entry.
68 */
69static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
71/*
72 * Radix tree node cache.
73 */
Christoph Lametere18b8902006-12-06 20:33:20 -080074static struct kmem_cache *radix_tree_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
76/*
77 * Per-cpu pool of preloaded nodes
78 */
79struct radix_tree_preload {
80 int nr;
81 struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
82};
Harvey Harrison8cef7d52009-01-06 14:40:50 -080083static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Nick Piggin612d6c12006-06-23 02:03:22 -070085static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
86{
87 return root->gfp_mask & __GFP_BITS_MASK;
88}
89
Nick Piggin643b52b2008-06-12 15:21:52 -070090static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
91 int offset)
92{
93 __set_bit(offset, node->tags[tag]);
94}
95
96static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
97 int offset)
98{
99 __clear_bit(offset, node->tags[tag]);
100}
101
102static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
103 int offset)
104{
105 return test_bit(offset, node->tags[tag]);
106}
107
108static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
109{
110 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
111}
112
113static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
114{
115 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
116}
117
118static inline void root_tag_clear_all(struct radix_tree_root *root)
119{
120 root->gfp_mask &= __GFP_BITS_MASK;
121}
122
123static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
124{
125 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
126}
127
128/*
129 * Returns 1 if any slot in the node has this tag set.
130 * Otherwise returns 0.
131 */
132static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
133{
134 int idx;
135 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
136 if (node->tags[tag][idx])
137 return 1;
138 }
139 return 0;
140}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141/*
142 * This assumes that the caller has performed appropriate preallocation, and
143 * that the caller has pinned this thread of control to the current CPU.
144 */
145static struct radix_tree_node *
146radix_tree_node_alloc(struct radix_tree_root *root)
147{
Nick Piggine2848a02008-02-04 22:29:10 -0800148 struct radix_tree_node *ret = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700149 gfp_t gfp_mask = root_gfp_mask(root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150
Nick Piggine2848a02008-02-04 22:29:10 -0800151 if (!(gfp_mask & __GFP_WAIT)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 struct radix_tree_preload *rtp;
153
Nick Piggine2848a02008-02-04 22:29:10 -0800154 /*
155 * Provided the caller has preloaded here, we will always
156 * succeed in getting a node here (and never reach
157 * kmem_cache_alloc)
158 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 rtp = &__get_cpu_var(radix_tree_preloads);
160 if (rtp->nr) {
161 ret = rtp->nodes[rtp->nr - 1];
162 rtp->nodes[rtp->nr - 1] = NULL;
163 rtp->nr--;
164 }
165 }
Nick Piggine2848a02008-02-04 22:29:10 -0800166 if (ret == NULL)
Christoph Lameter488514d2008-04-28 02:12:05 -0700167 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Nick Piggine2848a02008-02-04 22:29:10 -0800168
Nick Pigginc0bc9872007-10-16 01:24:42 -0700169 BUG_ON(radix_tree_is_indirect_ptr(ret));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 return ret;
171}
172
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800173static void radix_tree_node_rcu_free(struct rcu_head *head)
174{
175 struct radix_tree_node *node =
176 container_of(head, struct radix_tree_node, rcu_head);
Nick Piggin643b52b2008-06-12 15:21:52 -0700177
178 /*
179 * must only free zeroed nodes into the slab. radix_tree_shrink
180 * can leave us with a non-NULL entry in the first slot, so clear
181 * that here to make sure.
182 */
183 tag_clear(node, 0, 0);
184 tag_clear(node, 1, 0);
185 node->slots[0] = NULL;
186 node->count = 0;
187
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800188 kmem_cache_free(radix_tree_node_cachep, node);
189}
190
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191static inline void
192radix_tree_node_free(struct radix_tree_node *node)
193{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800194 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195}
196
197/*
198 * Load up this CPU's radix_tree_node buffer with sufficient objects to
199 * ensure that the addition of a single element in the tree cannot fail. On
200 * success, return zero, with preemption disabled. On error, return -ENOMEM
201 * with preemption not disabled.
David Howellsb34df792009-11-19 18:11:14 +0000202 *
203 * To make use of this facility, the radix tree must be initialised without
204 * __GFP_WAIT being passed to INIT_RADIX_TREE().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 */
Al Virodd0fc662005-10-07 07:46:04 +0100206int radix_tree_preload(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207{
208 struct radix_tree_preload *rtp;
209 struct radix_tree_node *node;
210 int ret = -ENOMEM;
211
212 preempt_disable();
213 rtp = &__get_cpu_var(radix_tree_preloads);
214 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
215 preempt_enable();
Christoph Lameter488514d2008-04-28 02:12:05 -0700216 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 if (node == NULL)
218 goto out;
219 preempt_disable();
220 rtp = &__get_cpu_var(radix_tree_preloads);
221 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
222 rtp->nodes[rtp->nr++] = node;
223 else
224 kmem_cache_free(radix_tree_node_cachep, node);
225 }
226 ret = 0;
227out:
228 return ret;
229}
David Chinnerd7f09232007-07-14 16:05:04 +1000230EXPORT_SYMBOL(radix_tree_preload);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
Nick Piggin6e954b92006-01-08 01:01:40 -0800232/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 * Return the maximum key which can be store into a
234 * radix tree with height HEIGHT.
235 */
236static inline unsigned long radix_tree_maxindex(unsigned int height)
237{
238 return height_to_maxindex[height];
239}
240
241/*
242 * Extend a radix tree so it can store key @index.
243 */
244static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
245{
246 struct radix_tree_node *node;
247 unsigned int height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 int tag;
249
250 /* Figure out what the height should be. */
251 height = root->height + 1;
252 while (index > radix_tree_maxindex(height))
253 height++;
254
255 if (root->rnode == NULL) {
256 root->height = height;
257 goto out;
258 }
259
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 do {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800261 unsigned int newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 if (!(node = radix_tree_node_alloc(root)))
263 return -ENOMEM;
264
265 /* Increase the height. */
Nick Pigginc0bc9872007-10-16 01:24:42 -0700266 node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267
268 /* Propagate the aggregated tag info into the new root */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800269 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -0700270 if (root_tag_get(root, tag))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 tag_set(node, tag, 0);
272 }
273
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800274 newheight = root->height+1;
275 node->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 node->count = 1;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700277 node = radix_tree_ptr_to_indirect(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800278 rcu_assign_pointer(root->rnode, node);
279 root->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 } while (height > root->height);
281out:
282 return 0;
283}
284
285/**
286 * radix_tree_insert - insert into a radix tree
287 * @root: radix tree root
288 * @index: index key
289 * @item: item to insert
290 *
291 * Insert an item into the radix tree at position @index.
292 */
293int radix_tree_insert(struct radix_tree_root *root,
294 unsigned long index, void *item)
295{
Christoph Lameter201b6262005-09-06 15:16:46 -0700296 struct radix_tree_node *node = NULL, *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 unsigned int height, shift;
298 int offset;
299 int error;
300
Nick Pigginc0bc9872007-10-16 01:24:42 -0700301 BUG_ON(radix_tree_is_indirect_ptr(item));
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 /* Make sure the tree is high enough. */
Nick Piggin612d6c12006-06-23 02:03:22 -0700304 if (index > radix_tree_maxindex(root->height)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 error = radix_tree_extend(root, index);
306 if (error)
307 return error;
308 }
309
Nick Pigginc0bc9872007-10-16 01:24:42 -0700310 slot = radix_tree_indirect_to_ptr(root->rnode);
311
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 height = root->height;
313 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
314
315 offset = 0; /* uninitialised var warning */
Nick Piggin612d6c12006-06-23 02:03:22 -0700316 while (height > 0) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700317 if (slot == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 /* Have to add a child node. */
Christoph Lameter201b6262005-09-06 15:16:46 -0700319 if (!(slot = radix_tree_node_alloc(root)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 return -ENOMEM;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800321 slot->height = height;
Christoph Lameter201b6262005-09-06 15:16:46 -0700322 if (node) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800323 rcu_assign_pointer(node->slots[offset], slot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 node->count++;
Christoph Lameter201b6262005-09-06 15:16:46 -0700325 } else
Nick Pigginc0bc9872007-10-16 01:24:42 -0700326 rcu_assign_pointer(root->rnode,
327 radix_tree_ptr_to_indirect(slot));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 }
329
330 /* Go a level down */
331 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Christoph Lameter201b6262005-09-06 15:16:46 -0700332 node = slot;
333 slot = node->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 shift -= RADIX_TREE_MAP_SHIFT;
335 height--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700336 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Christoph Lameter201b6262005-09-06 15:16:46 -0700338 if (slot != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 return -EEXIST;
Christoph Lameter201b6262005-09-06 15:16:46 -0700340
Nick Piggin612d6c12006-06-23 02:03:22 -0700341 if (node) {
342 node->count++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800343 rcu_assign_pointer(node->slots[offset], item);
Nick Piggin612d6c12006-06-23 02:03:22 -0700344 BUG_ON(tag_get(node, 0, offset));
345 BUG_ON(tag_get(node, 1, offset));
346 } else {
Nick Pigginc0bc9872007-10-16 01:24:42 -0700347 rcu_assign_pointer(root->rnode, item);
Nick Piggin612d6c12006-06-23 02:03:22 -0700348 BUG_ON(root_tag_get(root, 0));
349 BUG_ON(root_tag_get(root, 1));
350 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 return 0;
353}
354EXPORT_SYMBOL(radix_tree_insert);
355
Huang Shijieb72b71c2009-06-16 15:33:42 -0700356/*
357 * is_slot == 1 : search for the slot.
358 * is_slot == 0 : search for the node.
Hans Reisera4331362005-11-07 00:59:29 -0800359 */
Huang Shijieb72b71c2009-06-16 15:33:42 -0700360static void *radix_tree_lookup_element(struct radix_tree_root *root,
361 unsigned long index, int is_slot)
Hans Reisera4331362005-11-07 00:59:29 -0800362{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800363 unsigned int height, shift;
364 struct radix_tree_node *node, **slot;
365
Paul E. McKenney2676a582010-02-22 17:04:54 -0800366 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800367 if (node == NULL)
368 return NULL;
369
Nick Pigginc0bc9872007-10-16 01:24:42 -0700370 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800371 if (index > 0)
372 return NULL;
Huang Shijieb72b71c2009-06-16 15:33:42 -0700373 return is_slot ? (void *)&root->rnode : node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800374 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700375 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800376
377 height = node->height;
378 if (index > radix_tree_maxindex(height))
379 return NULL;
380
381 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
382
383 do {
384 slot = (struct radix_tree_node **)
385 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
Paul E. McKenney2676a582010-02-22 17:04:54 -0800386 node = rcu_dereference_raw(*slot);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800387 if (node == NULL)
388 return NULL;
389
390 shift -= RADIX_TREE_MAP_SHIFT;
391 height--;
392 } while (height > 0);
393
Huang Shijieb72b71c2009-06-16 15:33:42 -0700394 return is_slot ? (void *)slot:node;
395}
396
397/**
398 * radix_tree_lookup_slot - lookup a slot in a radix tree
399 * @root: radix tree root
400 * @index: index key
401 *
402 * Returns: the slot corresponding to the position @index in the
403 * radix tree @root. This is useful for update-if-exists operations.
404 *
405 * This function can be called under rcu_read_lock iff the slot is not
406 * modified by radix_tree_replace_slot, otherwise it must be called
407 * exclusive from other writers. Any dereference of the slot must be done
408 * using radix_tree_deref_slot.
409 */
410void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
411{
412 return (void **)radix_tree_lookup_element(root, index, 1);
Hans Reisera4331362005-11-07 00:59:29 -0800413}
414EXPORT_SYMBOL(radix_tree_lookup_slot);
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416/**
417 * radix_tree_lookup - perform lookup operation on a radix tree
418 * @root: radix tree root
419 * @index: index key
420 *
421 * Lookup the item at the position @index in the radix tree @root.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800422 *
423 * This function can be called under rcu_read_lock, however the caller
424 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
425 * them safely). No RCU barriers are required to access or modify the
426 * returned item, however.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 */
428void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
429{
Huang Shijieb72b71c2009-06-16 15:33:42 -0700430 return radix_tree_lookup_element(root, index, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431}
432EXPORT_SYMBOL(radix_tree_lookup);
433
434/**
435 * radix_tree_tag_set - set a tag on a radix tree node
436 * @root: radix tree root
437 * @index: index key
438 * @tag: tag index
439 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800440 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
441 * corresponding to @index in the radix tree. From
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 * the root all the way down to the leaf node.
443 *
444 * Returns the address of the tagged item. Setting a tag on a not-present
445 * item is a bug.
446 */
447void *radix_tree_tag_set(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800448 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449{
450 unsigned int height, shift;
Christoph Lameter201b6262005-09-06 15:16:46 -0700451 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453 height = root->height;
Peter Zijlstra4c91c362006-06-23 02:03:25 -0700454 BUG_ON(index > radix_tree_maxindex(height));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455
Nick Pigginc0bc9872007-10-16 01:24:42 -0700456 slot = radix_tree_indirect_to_ptr(root->rnode);
Nick Piggin612d6c12006-06-23 02:03:22 -0700457 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458
459 while (height > 0) {
460 int offset;
461
462 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggind5274262006-01-08 01:01:41 -0800463 if (!tag_get(slot, tag, offset))
464 tag_set(slot, tag, offset);
Christoph Lameter201b6262005-09-06 15:16:46 -0700465 slot = slot->slots[offset];
466 BUG_ON(slot == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 shift -= RADIX_TREE_MAP_SHIFT;
468 height--;
469 }
470
Nick Piggin612d6c12006-06-23 02:03:22 -0700471 /* set the root's tag bit */
472 if (slot && !root_tag_get(root, tag))
473 root_tag_set(root, tag);
474
Christoph Lameter201b6262005-09-06 15:16:46 -0700475 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476}
477EXPORT_SYMBOL(radix_tree_tag_set);
478
479/**
480 * radix_tree_tag_clear - clear a tag on a radix tree node
481 * @root: radix tree root
482 * @index: index key
483 * @tag: tag index
484 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800485 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
486 * corresponding to @index in the radix tree. If
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 * this causes the leaf node to have no tags set then clear the tag in the
488 * next-to-leaf node, etc.
489 *
490 * Returns the address of the tagged item on success, else NULL. ie:
491 * has the same return value and semantics as radix_tree_lookup().
492 */
493void *radix_tree_tag_clear(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800494 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
Jeff Moyer26fb1582007-10-16 01:24:49 -0700496 /*
497 * The radix tree path needs to be one longer than the maximum path
498 * since the "list" is null terminated.
499 */
500 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -0700501 struct radix_tree_node *slot = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 unsigned int height, shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503
504 height = root->height;
505 if (index > radix_tree_maxindex(height))
506 goto out;
507
508 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
509 pathp->node = NULL;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700510 slot = radix_tree_indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511
512 while (height > 0) {
513 int offset;
514
Christoph Lameter201b6262005-09-06 15:16:46 -0700515 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 goto out;
517
518 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
519 pathp[1].offset = offset;
Christoph Lameter201b6262005-09-06 15:16:46 -0700520 pathp[1].node = slot;
521 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 pathp++;
523 shift -= RADIX_TREE_MAP_SHIFT;
524 height--;
525 }
526
Nick Piggin612d6c12006-06-23 02:03:22 -0700527 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 goto out;
529
Nick Piggin612d6c12006-06-23 02:03:22 -0700530 while (pathp->node) {
Nick Piggind5274262006-01-08 01:01:41 -0800531 if (!tag_get(pathp->node, tag, pathp->offset))
532 goto out;
Christoph Lameter201b6262005-09-06 15:16:46 -0700533 tag_clear(pathp->node, tag, pathp->offset);
Nick Piggin6e954b92006-01-08 01:01:40 -0800534 if (any_tag_set(pathp->node, tag))
535 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 pathp--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700537 }
538
539 /* clear the root's tag bit */
540 if (root_tag_get(root, tag))
541 root_tag_clear(root, tag);
542
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543out:
Nick Piggin612d6c12006-06-23 02:03:22 -0700544 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545}
546EXPORT_SYMBOL(radix_tree_tag_clear);
547
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548/**
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700549 * radix_tree_tag_get - get a tag on a radix tree node
550 * @root: radix tree root
551 * @index: index key
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800552 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 *
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700554 * Return values:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 *
Nick Piggin612d6c12006-06-23 02:03:22 -0700556 * 0: tag not present or not set
557 * 1: tag set
David Howellsce826532010-04-06 22:36:20 +0100558 *
559 * Note that the return value of this function may not be relied on, even if
560 * the RCU lock is held, unless tag modification and node deletion are excluded
561 * from concurrency.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 */
563int radix_tree_tag_get(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800564 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565{
566 unsigned int height, shift;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800567 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 int saw_unset_tag = 0;
569
Nick Piggin612d6c12006-06-23 02:03:22 -0700570 /* check the root's tag bit */
571 if (!root_tag_get(root, tag))
572 return 0;
573
Paul E. McKenney2676a582010-02-22 17:04:54 -0800574 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800575 if (node == NULL)
576 return 0;
577
Nick Pigginc0bc9872007-10-16 01:24:42 -0700578 if (!radix_tree_is_indirect_ptr(node))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800579 return (index == 0);
Nick Pigginc0bc9872007-10-16 01:24:42 -0700580 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800581
582 height = node->height;
583 if (index > radix_tree_maxindex(height))
584 return 0;
Nick Piggin612d6c12006-06-23 02:03:22 -0700585
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587
588 for ( ; ; ) {
589 int offset;
590
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800591 if (node == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 return 0;
593
594 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
595
596 /*
597 * This is just a debug check. Later, we can bale as soon as
598 * we see an unset tag.
599 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800600 if (!tag_get(node, tag, offset))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 saw_unset_tag = 1;
David Howellsce826532010-04-06 22:36:20 +0100602 if (height == 1)
603 return !!tag_get(node, tag, offset);
Paul E. McKenney2676a582010-02-22 17:04:54 -0800604 node = rcu_dereference_raw(node->slots[offset]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 shift -= RADIX_TREE_MAP_SHIFT;
606 height--;
607 }
608}
609EXPORT_SYMBOL(radix_tree_tag_get);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700611/**
612 * radix_tree_next_hole - find the next hole (not-present entry)
613 * @root: tree root
614 * @index: index key
615 * @max_scan: maximum range to search
616 *
617 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
618 * indexed hole.
619 *
620 * Returns: the index of the hole if found, otherwise returns an index
621 * outside of the set specified (in which case 'return - index >= max_scan'
Wu Fengguang8e6bdb72008-11-27 11:42:22 +0100622 * will be true). In rare cases of index wrap-around, 0 will be returned.
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700623 *
624 * radix_tree_next_hole may be called under rcu_read_lock. However, like
Wu Fengguang8e6bdb72008-11-27 11:42:22 +0100625 * radix_tree_gang_lookup, this will not atomically search a snapshot of
626 * the tree at a single point in time. For example, if a hole is created
627 * at index 5, then subsequently a hole is created at index 10,
628 * radix_tree_next_hole covering both indexes may return 10 if called
629 * under rcu_read_lock.
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700630 */
631unsigned long radix_tree_next_hole(struct radix_tree_root *root,
632 unsigned long index, unsigned long max_scan)
633{
634 unsigned long i;
635
636 for (i = 0; i < max_scan; i++) {
637 if (!radix_tree_lookup(root, index))
638 break;
639 index++;
640 if (index == 0)
641 break;
642 }
643
644 return index;
645}
646EXPORT_SYMBOL(radix_tree_next_hole);
647
Wu Fengguangdc566122009-06-16 15:31:32 -0700648/**
649 * radix_tree_prev_hole - find the prev hole (not-present entry)
650 * @root: tree root
651 * @index: index key
652 * @max_scan: maximum range to search
653 *
654 * Search backwards in the range [max(index-max_scan+1, 0), index]
655 * for the first hole.
656 *
657 * Returns: the index of the hole if found, otherwise returns an index
658 * outside of the set specified (in which case 'index - return >= max_scan'
Cesar Eduardo Barrosedcd1d82010-05-26 14:44:27 -0700659 * will be true). In rare cases of wrap-around, ULONG_MAX will be returned.
Wu Fengguangdc566122009-06-16 15:31:32 -0700660 *
661 * radix_tree_next_hole may be called under rcu_read_lock. However, like
662 * radix_tree_gang_lookup, this will not atomically search a snapshot of
663 * the tree at a single point in time. For example, if a hole is created
664 * at index 10, then subsequently a hole is created at index 5,
665 * radix_tree_prev_hole covering both indexes may return 5 if called under
666 * rcu_read_lock.
667 */
668unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
669 unsigned long index, unsigned long max_scan)
670{
671 unsigned long i;
672
673 for (i = 0; i < max_scan; i++) {
674 if (!radix_tree_lookup(root, index))
675 break;
676 index--;
Cesar Eduardo Barrosedcd1d82010-05-26 14:44:27 -0700677 if (index == ULONG_MAX)
Wu Fengguangdc566122009-06-16 15:31:32 -0700678 break;
679 }
680
681 return index;
682}
683EXPORT_SYMBOL(radix_tree_prev_hole);
684
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685static unsigned int
Nick Piggin47feff22008-07-25 19:45:29 -0700686__lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 unsigned int max_items, unsigned long *next_index)
688{
689 unsigned int nr_found = 0;
Christoph Lameter201b6262005-09-06 15:16:46 -0700690 unsigned int shift, height;
Christoph Lameter201b6262005-09-06 15:16:46 -0700691 unsigned long i;
692
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800693 height = slot->height;
694 if (height == 0)
Christoph Lameter201b6262005-09-06 15:16:46 -0700695 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697
Christoph Lameter201b6262005-09-06 15:16:46 -0700698 for ( ; height > 1; height--) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800699 i = (index >> shift) & RADIX_TREE_MAP_MASK;
700 for (;;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 if (slot->slots[i] != NULL)
702 break;
703 index &= ~((1UL << shift) - 1);
704 index += 1UL << shift;
705 if (index == 0)
706 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800707 i++;
708 if (i == RADIX_TREE_MAP_SIZE)
709 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 shift -= RADIX_TREE_MAP_SHIFT;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800713 slot = rcu_dereference_raw(slot->slots[i]);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800714 if (slot == NULL)
715 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 }
Christoph Lameter201b6262005-09-06 15:16:46 -0700717
718 /* Bottom level: grab some items */
719 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
720 index++;
Nick Piggin47feff22008-07-25 19:45:29 -0700721 if (slot->slots[i]) {
722 results[nr_found++] = &(slot->slots[i]);
Christoph Lameter201b6262005-09-06 15:16:46 -0700723 if (nr_found == max_items)
724 goto out;
725 }
726 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727out:
728 *next_index = index;
729 return nr_found;
730}
731
732/**
733 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
734 * @root: radix tree root
735 * @results: where the results of the lookup are placed
736 * @first_index: start the lookup from this key
737 * @max_items: place up to this many items at *results
738 *
739 * Performs an index-ascending scan of the tree for present items. Places
740 * them at *@results and returns the number of items which were placed at
741 * *@results.
742 *
743 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800744 *
745 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
746 * rcu_read_lock. In this case, rather than the returned results being
747 * an atomic snapshot of the tree at a single point in time, the semantics
748 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
749 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 */
751unsigned int
752radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
753 unsigned long first_index, unsigned int max_items)
754{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800755 unsigned long max_index;
756 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800758 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759
Paul E. McKenney2676a582010-02-22 17:04:54 -0800760 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800761 if (!node)
762 return 0;
763
Nick Pigginc0bc9872007-10-16 01:24:42 -0700764 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800765 if (first_index > 0)
766 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700767 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800768 return 1;
769 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700770 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800771
772 max_index = radix_tree_maxindex(node->height);
773
774 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700776 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 unsigned long next_index; /* Index of next search */
778
779 if (cur_index > max_index)
780 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700781 slots_found = __lookup(node, (void ***)results + ret, cur_index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 max_items - ret, &next_index);
Nick Piggin47feff22008-07-25 19:45:29 -0700783 nr_found = 0;
784 for (i = 0; i < slots_found; i++) {
785 struct radix_tree_node *slot;
786 slot = *(((void ***)results)[ret + i]);
787 if (!slot)
788 continue;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800789 results[ret + nr_found] = rcu_dereference_raw(slot);
Nick Piggin47feff22008-07-25 19:45:29 -0700790 nr_found++;
791 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 ret += nr_found;
793 if (next_index == 0)
794 break;
795 cur_index = next_index;
796 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800797
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 return ret;
799}
800EXPORT_SYMBOL(radix_tree_gang_lookup);
801
Nick Piggin47feff22008-07-25 19:45:29 -0700802/**
803 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
804 * @root: radix tree root
805 * @results: where the results of the lookup are placed
806 * @first_index: start the lookup from this key
807 * @max_items: place up to this many items at *results
808 *
809 * Performs an index-ascending scan of the tree for present items. Places
810 * their slots at *@results and returns the number of items which were
811 * placed at *@results.
812 *
813 * The implementation is naive.
814 *
815 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
816 * be dereferenced with radix_tree_deref_slot, and if using only RCU
817 * protection, radix_tree_deref_slot may fail requiring a retry.
818 */
819unsigned int
820radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
821 unsigned long first_index, unsigned int max_items)
822{
823 unsigned long max_index;
824 struct radix_tree_node *node;
825 unsigned long cur_index = first_index;
826 unsigned int ret;
827
Paul E. McKenney2676a582010-02-22 17:04:54 -0800828 node = rcu_dereference_raw(root->rnode);
Nick Piggin47feff22008-07-25 19:45:29 -0700829 if (!node)
830 return 0;
831
832 if (!radix_tree_is_indirect_ptr(node)) {
833 if (first_index > 0)
834 return 0;
835 results[0] = (void **)&root->rnode;
836 return 1;
837 }
838 node = radix_tree_indirect_to_ptr(node);
839
840 max_index = radix_tree_maxindex(node->height);
841
842 ret = 0;
843 while (ret < max_items) {
844 unsigned int slots_found;
845 unsigned long next_index; /* Index of next search */
846
847 if (cur_index > max_index)
848 break;
849 slots_found = __lookup(node, results + ret, cur_index,
850 max_items - ret, &next_index);
851 ret += slots_found;
852 if (next_index == 0)
853 break;
854 cur_index = next_index;
855 }
856
857 return ret;
858}
859EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
860
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861/*
862 * FIXME: the two tag_get()s here should use find_next_bit() instead of
863 * open-coding the search.
864 */
865static unsigned int
Nick Piggin47feff22008-07-25 19:45:29 -0700866__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800867 unsigned int max_items, unsigned long *next_index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868{
869 unsigned int nr_found = 0;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800870 unsigned int shift, height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800872 height = slot->height;
873 if (height == 0)
Nick Piggin612d6c12006-06-23 02:03:22 -0700874 goto out;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800875 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -0700876
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800877 while (height > 0) {
878 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800880 for (;;) {
881 if (tag_get(slot, tag, i))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 index &= ~((1UL << shift) - 1);
884 index += 1UL << shift;
885 if (index == 0)
886 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800887 i++;
888 if (i == RADIX_TREE_MAP_SIZE)
889 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 height--;
892 if (height == 0) { /* Bottom level: grab some items */
893 unsigned long j = index & RADIX_TREE_MAP_MASK;
894
895 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
896 index++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800897 if (!tag_get(slot, tag, j))
898 continue;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800899 /*
900 * Even though the tag was found set, we need to
901 * recheck that we have a non-NULL node, because
902 * if this lookup is lockless, it may have been
903 * subsequently deleted.
904 *
905 * Similar care must be taken in any place that
906 * lookup ->slots[x] without a lock (ie. can't
907 * rely on its value remaining the same).
908 */
Nick Piggin47feff22008-07-25 19:45:29 -0700909 if (slot->slots[j]) {
910 results[nr_found++] = &(slot->slots[j]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 if (nr_found == max_items)
912 goto out;
913 }
914 }
915 }
916 shift -= RADIX_TREE_MAP_SHIFT;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800917 slot = rcu_dereference_raw(slot->slots[i]);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800918 if (slot == NULL)
919 break;
920 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921out:
922 *next_index = index;
923 return nr_found;
924}
925
926/**
927 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
928 * based on a tag
929 * @root: radix tree root
930 * @results: where the results of the lookup are placed
931 * @first_index: start the lookup from this key
932 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800933 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 *
935 * Performs an index-ascending scan of the tree for present items which
936 * have the tag indexed by @tag set. Places the items at *@results and
937 * returns the number of items which were placed at *@results.
938 */
939unsigned int
940radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800941 unsigned long first_index, unsigned int max_items,
942 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800944 struct radix_tree_node *node;
945 unsigned long max_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800947 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
Nick Piggin612d6c12006-06-23 02:03:22 -0700949 /* check the root's tag bit */
950 if (!root_tag_get(root, tag))
951 return 0;
952
Paul E. McKenney2676a582010-02-22 17:04:54 -0800953 node = rcu_dereference_raw(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800954 if (!node)
955 return 0;
956
Nick Pigginc0bc9872007-10-16 01:24:42 -0700957 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800958 if (first_index > 0)
959 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700960 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800961 return 1;
962 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700963 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800964
965 max_index = radix_tree_maxindex(node->height);
966
967 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700969 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 unsigned long next_index; /* Index of next search */
971
972 if (cur_index > max_index)
973 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700974 slots_found = __lookup_tag(node, (void ***)results + ret,
975 cur_index, max_items - ret, &next_index, tag);
976 nr_found = 0;
977 for (i = 0; i < slots_found; i++) {
978 struct radix_tree_node *slot;
979 slot = *(((void ***)results)[ret + i]);
980 if (!slot)
981 continue;
Paul E. McKenney2676a582010-02-22 17:04:54 -0800982 results[ret + nr_found] = rcu_dereference_raw(slot);
Nick Piggin47feff22008-07-25 19:45:29 -0700983 nr_found++;
984 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 ret += nr_found;
986 if (next_index == 0)
987 break;
988 cur_index = next_index;
989 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 return ret;
992}
993EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
994
995/**
Nick Piggin47feff22008-07-25 19:45:29 -0700996 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
997 * radix tree based on a tag
998 * @root: radix tree root
999 * @results: where the results of the lookup are placed
1000 * @first_index: start the lookup from this key
1001 * @max_items: place up to this many items at *results
1002 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1003 *
1004 * Performs an index-ascending scan of the tree for present items which
1005 * have the tag indexed by @tag set. Places the slots at *@results and
1006 * returns the number of slots which were placed at *@results.
1007 */
1008unsigned int
1009radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
1010 unsigned long first_index, unsigned int max_items,
1011 unsigned int tag)
1012{
1013 struct radix_tree_node *node;
1014 unsigned long max_index;
1015 unsigned long cur_index = first_index;
1016 unsigned int ret;
1017
1018 /* check the root's tag bit */
1019 if (!root_tag_get(root, tag))
1020 return 0;
1021
Paul E. McKenney2676a582010-02-22 17:04:54 -08001022 node = rcu_dereference_raw(root->rnode);
Nick Piggin47feff22008-07-25 19:45:29 -07001023 if (!node)
1024 return 0;
1025
1026 if (!radix_tree_is_indirect_ptr(node)) {
1027 if (first_index > 0)
1028 return 0;
1029 results[0] = (void **)&root->rnode;
1030 return 1;
1031 }
1032 node = radix_tree_indirect_to_ptr(node);
1033
1034 max_index = radix_tree_maxindex(node->height);
1035
1036 ret = 0;
1037 while (ret < max_items) {
1038 unsigned int slots_found;
1039 unsigned long next_index; /* Index of next search */
1040
1041 if (cur_index > max_index)
1042 break;
1043 slots_found = __lookup_tag(node, results + ret,
1044 cur_index, max_items - ret, &next_index, tag);
1045 ret += slots_found;
1046 if (next_index == 0)
1047 break;
1048 cur_index = next_index;
1049 }
1050
1051 return ret;
1052}
1053EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1054
1055
1056/**
Nick Piggina5f51c92006-01-08 01:01:41 -08001057 * radix_tree_shrink - shrink height of a radix tree to minimal
1058 * @root radix tree root
1059 */
1060static inline void radix_tree_shrink(struct radix_tree_root *root)
1061{
1062 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -07001063 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -08001064 struct radix_tree_node *to_free = root->rnode;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001065 void *newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001066
Nick Pigginc0bc9872007-10-16 01:24:42 -07001067 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
1068 to_free = radix_tree_indirect_to_ptr(to_free);
1069
1070 /*
1071 * The candidate node has more than one child, or its child
1072 * is not at the leftmost slot, we cannot shrink.
1073 */
1074 if (to_free->count != 1)
1075 break;
1076 if (!to_free->slots[0])
1077 break;
1078
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001079 /*
1080 * We don't need rcu_assign_pointer(), since we are simply
1081 * moving the node from one part of the tree to another. If
1082 * it was safe to dereference the old pointer to it
1083 * (to_free->slots[0]), it will be safe to dereference the new
1084 * one (root->rnode).
1085 */
1086 newptr = to_free->slots[0];
Nick Pigginc0bc9872007-10-16 01:24:42 -07001087 if (root->height > 1)
1088 newptr = radix_tree_ptr_to_indirect(newptr);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001089 root->rnode = newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001090 root->height--;
Nick Piggina5f51c92006-01-08 01:01:41 -08001091 radix_tree_node_free(to_free);
1092 }
1093}
1094
1095/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 * radix_tree_delete - delete an item from a radix tree
1097 * @root: radix tree root
1098 * @index: index key
1099 *
1100 * Remove the item at @index from the radix tree rooted at @root.
1101 *
1102 * Returns the address of the deleted item, or NULL if it was not present.
1103 */
1104void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1105{
Jeff Moyer26fb1582007-10-16 01:24:49 -07001106 /*
1107 * The radix tree path needs to be one longer than the maximum path
1108 * since the "list" is null terminated.
1109 */
1110 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -07001111 struct radix_tree_node *slot = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001112 struct radix_tree_node *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 unsigned int height, shift;
Nick Piggind5274262006-01-08 01:01:41 -08001114 int tag;
1115 int offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
1117 height = root->height;
1118 if (index > radix_tree_maxindex(height))
1119 goto out;
1120
Nick Piggin612d6c12006-06-23 02:03:22 -07001121 slot = root->rnode;
Nick Pigginc0bc9872007-10-16 01:24:42 -07001122 if (height == 0) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001123 root_tag_clear_all(root);
1124 root->rnode = NULL;
1125 goto out;
1126 }
Nick Pigginc0bc9872007-10-16 01:24:42 -07001127 slot = radix_tree_indirect_to_ptr(slot);
Nick Piggin612d6c12006-06-23 02:03:22 -07001128
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
1130 pathp->node = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131
Nick Piggin612d6c12006-06-23 02:03:22 -07001132 do {
Christoph Lameter201b6262005-09-06 15:16:46 -07001133 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 goto out;
1135
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 pathp++;
Nick Piggind5274262006-01-08 01:01:41 -08001137 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
1138 pathp->offset = offset;
1139 pathp->node = slot;
1140 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -07001142 height--;
1143 } while (height > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
Nick Piggin612d6c12006-06-23 02:03:22 -07001145 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 goto out;
1147
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148 /*
1149 * Clear all tags associated with the just-deleted item
1150 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001151 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001152 if (tag_get(pathp->node, tag, pathp->offset))
1153 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001154 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001156 to_free = NULL;
Christoph Lameter201b6262005-09-06 15:16:46 -07001157 /* Now free the nodes we do not need anymore */
Nick Piggin612d6c12006-06-23 02:03:22 -07001158 while (pathp->node) {
Christoph Lameter201b6262005-09-06 15:16:46 -07001159 pathp->node->slots[pathp->offset] = NULL;
Nick Piggina5f51c92006-01-08 01:01:41 -08001160 pathp->node->count--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001161 /*
1162 * Queue the node for deferred freeing after the
1163 * last reference to it disappears (set NULL, above).
1164 */
1165 if (to_free)
1166 radix_tree_node_free(to_free);
Nick Piggina5f51c92006-01-08 01:01:41 -08001167
1168 if (pathp->node->count) {
Nick Pigginc0bc9872007-10-16 01:24:42 -07001169 if (pathp->node ==
1170 radix_tree_indirect_to_ptr(root->rnode))
Nick Piggina5f51c92006-01-08 01:01:41 -08001171 radix_tree_shrink(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001172 goto out;
Nick Piggina5f51c92006-01-08 01:01:41 -08001173 }
Christoph Lameter201b6262005-09-06 15:16:46 -07001174
1175 /* Node with zero slots in use so free it */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001176 to_free = pathp->node;
Nick Piggin612d6c12006-06-23 02:03:22 -07001177 pathp--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001178
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 }
Nick Piggin612d6c12006-06-23 02:03:22 -07001180 root_tag_clear_all(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001181 root->height = 0;
Nick Piggin612d6c12006-06-23 02:03:22 -07001182 root->rnode = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001183 if (to_free)
1184 radix_tree_node_free(to_free);
Nick Piggin612d6c12006-06-23 02:03:22 -07001185
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186out:
Nick Piggin612d6c12006-06-23 02:03:22 -07001187 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188}
1189EXPORT_SYMBOL(radix_tree_delete);
1190
1191/**
1192 * radix_tree_tagged - test whether any items in the tree are tagged
1193 * @root: radix tree root
1194 * @tag: tag to test
1195 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001196int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197{
Nick Piggin612d6c12006-06-23 02:03:22 -07001198 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199}
1200EXPORT_SYMBOL(radix_tree_tagged);
1201
1202static void
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07001203radix_tree_node_ctor(void *node)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204{
1205 memset(node, 0, sizeof(struct radix_tree_node));
1206}
1207
1208static __init unsigned long __maxindex(unsigned int height)
1209{
Peter Lund430d2752007-10-16 23:29:35 -07001210 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1211 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212
Peter Lund430d2752007-10-16 23:29:35 -07001213 if (shift < 0)
1214 return ~0UL;
1215 if (shift >= BITS_PER_LONG)
1216 return 0UL;
1217 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218}
1219
1220static __init void radix_tree_init_maxindex(void)
1221{
1222 unsigned int i;
1223
1224 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1225 height_to_maxindex[i] = __maxindex(i);
1226}
1227
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228static int radix_tree_callback(struct notifier_block *nfb,
1229 unsigned long action,
1230 void *hcpu)
1231{
1232 int cpu = (long)hcpu;
1233 struct radix_tree_preload *rtp;
1234
1235 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001236 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 rtp = &per_cpu(radix_tree_preloads, cpu);
1238 while (rtp->nr) {
1239 kmem_cache_free(radix_tree_node_cachep,
1240 rtp->nodes[rtp->nr-1]);
1241 rtp->nodes[rtp->nr-1] = NULL;
1242 rtp->nr--;
1243 }
1244 }
1245 return NOTIFY_OK;
1246}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247
1248void __init radix_tree_init(void)
1249{
1250 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1251 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001252 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1253 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 radix_tree_init_maxindex();
1255 hotcpu_notifier(radix_tree_callback, 0);
1256}