Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2001 Momchil Velikov |
| 3 | * Portions Copyright (C) 2001 Christoph Hellwig |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 4 | * Copyright (C) 2006 Nick Piggin |
Konstantin Khlebnikov | 78c1d78 | 2012-03-28 14:42:53 -0700 | [diff] [blame] | 5 | * Copyright (C) 2012 Konstantin Khlebnikov |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 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 | #ifndef _LINUX_RADIX_TREE_H |
| 22 | #define _LINUX_RADIX_TREE_H |
| 23 | |
| 24 | #include <linux/preempt.h> |
| 25 | #include <linux/types.h> |
Paul Gortmaker | 187f188 | 2011-11-23 20:12:59 -0500 | [diff] [blame] | 26 | #include <linux/bug.h> |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 27 | #include <linux/kernel.h> |
| 28 | #include <linux/rcupdate.h> |
| 29 | |
| 30 | /* |
Nick Piggin | c0bc987 | 2007-10-16 01:24:42 -0700 | [diff] [blame] | 31 | * An indirect pointer (root->rnode pointing to a radix_tree_node, rather |
| 32 | * than a data item) is signalled by the low bit set in the root->rnode |
| 33 | * pointer. |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 34 | * |
Nick Piggin | c0bc987 | 2007-10-16 01:24:42 -0700 | [diff] [blame] | 35 | * In this case root->height is > 0, but the indirect pointer tests are |
| 36 | * needed for RCU lookups (because root->height is unreliable). The only |
| 37 | * time callers need worry about this is when doing a lookup_slot under |
| 38 | * RCU. |
Nick Piggin | 27d20fd | 2010-11-11 14:05:19 -0800 | [diff] [blame] | 39 | * |
| 40 | * Indirect pointer in fact is also used to tag the last pointer of a node |
| 41 | * when it is shrunk, before we rcu free the node. See shrink code for |
| 42 | * details. |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 43 | */ |
Hugh Dickins | 6328650 | 2011-08-03 16:21:18 -0700 | [diff] [blame] | 44 | #define RADIX_TREE_INDIRECT_PTR 1 |
| 45 | /* |
| 46 | * A common use of the radix tree is to store pointers to struct pages; |
| 47 | * but shmem/tmpfs needs also to store swap entries in the same tree: |
| 48 | * those are marked as exceptional entries to distinguish them. |
| 49 | * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it. |
| 50 | */ |
| 51 | #define RADIX_TREE_EXCEPTIONAL_ENTRY 2 |
| 52 | #define RADIX_TREE_EXCEPTIONAL_SHIFT 2 |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 53 | |
Nick Piggin | c0bc987 | 2007-10-16 01:24:42 -0700 | [diff] [blame] | 54 | static inline int radix_tree_is_indirect_ptr(void *ptr) |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 55 | { |
Nick Piggin | c0bc987 | 2007-10-16 01:24:42 -0700 | [diff] [blame] | 56 | return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR); |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 57 | } |
| 58 | |
| 59 | /*** radix-tree API starts here ***/ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | |
Jan Kara | f446daae | 2010-08-09 17:19:12 -0700 | [diff] [blame] | 61 | #define RADIX_TREE_MAX_TAGS 3 |
Nick Piggin | 612d6c1 | 2006-06-23 02:03:22 -0700 | [diff] [blame] | 62 | |
| 63 | /* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | struct radix_tree_root { |
| 65 | unsigned int height; |
Al Viro | fd4f2df | 2005-10-21 03:18:50 -0400 | [diff] [blame] | 66 | gfp_t gfp_mask; |
Arnd Bergmann | a111557 | 2010-02-25 23:43:52 +0100 | [diff] [blame] | 67 | struct radix_tree_node __rcu *rnode; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | }; |
| 69 | |
| 70 | #define RADIX_TREE_INIT(mask) { \ |
| 71 | .height = 0, \ |
| 72 | .gfp_mask = (mask), \ |
| 73 | .rnode = NULL, \ |
| 74 | } |
| 75 | |
| 76 | #define RADIX_TREE(name, mask) \ |
| 77 | struct radix_tree_root name = RADIX_TREE_INIT(mask) |
| 78 | |
| 79 | #define INIT_RADIX_TREE(root, mask) \ |
| 80 | do { \ |
| 81 | (root)->height = 0; \ |
| 82 | (root)->gfp_mask = (mask); \ |
| 83 | (root)->rnode = NULL; \ |
| 84 | } while (0) |
| 85 | |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 86 | /** |
| 87 | * Radix-tree synchronization |
| 88 | * |
| 89 | * The radix-tree API requires that users provide all synchronisation (with |
| 90 | * specific exceptions, noted below). |
| 91 | * |
| 92 | * Synchronization of access to the data items being stored in the tree, and |
| 93 | * management of their lifetimes must be completely managed by API users. |
| 94 | * |
| 95 | * For API usage, in general, |
Michael Opdenacker | 59c5159 | 2007-05-09 08:57:56 +0200 | [diff] [blame] | 96 | * - any function _modifying_ the tree or tags (inserting or deleting |
Tim Pepper | eb8dc5e | 2008-02-03 16:12:47 +0200 | [diff] [blame] | 97 | * items, setting or clearing tags) must exclude other modifications, and |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 98 | * exclude any functions reading the tree. |
Michael Opdenacker | 59c5159 | 2007-05-09 08:57:56 +0200 | [diff] [blame] | 99 | * - any function _reading_ the tree or tags (looking up items or tags, |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 100 | * gang lookups) must exclude modifications to the tree, but may occur |
| 101 | * concurrently with other readers. |
| 102 | * |
| 103 | * The notable exceptions to this rule are the following functions: |
| 104 | * radix_tree_lookup |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 105 | * radix_tree_lookup_slot |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 106 | * radix_tree_tag_get |
| 107 | * radix_tree_gang_lookup |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 108 | * radix_tree_gang_lookup_slot |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 109 | * radix_tree_gang_lookup_tag |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 110 | * radix_tree_gang_lookup_tag_slot |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 111 | * radix_tree_tagged |
| 112 | * |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 113 | * The first 7 functions are able to be called locklessly, using RCU. The |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 114 | * caller must ensure calls to these functions are made within rcu_read_lock() |
| 115 | * regions. Other readers (lock-free or otherwise) and modifications may be |
| 116 | * running concurrently. |
| 117 | * |
| 118 | * It is still required that the caller manage the synchronization and lifetimes |
| 119 | * of the items. So if RCU lock-free lookups are used, typically this would mean |
| 120 | * that the items have their own locks, or are amenable to lock-free access; and |
| 121 | * that the items are freed by RCU (or only freed after having been deleted from |
| 122 | * the radix tree *and* a synchronize_rcu() grace period). |
| 123 | * |
| 124 | * (Note, rcu_assign_pointer and rcu_dereference are not needed to control |
| 125 | * access to data items when inserting into or looking up from the radix tree) |
| 126 | * |
David Howells | ce82653 | 2010-04-06 22:36:20 +0100 | [diff] [blame] | 127 | * Note that the value returned by radix_tree_tag_get() may not be relied upon |
| 128 | * if only the RCU read lock is held. Functions to set/clear tags and to |
| 129 | * delete nodes running concurrently with it may affect its result such that |
| 130 | * two consecutive reads in the same locked section may return different |
| 131 | * values. If reliability is required, modification functions must also be |
| 132 | * excluded from concurrency. |
| 133 | * |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 134 | * radix_tree_tagged is able to be called without locking or RCU. |
| 135 | */ |
| 136 | |
| 137 | /** |
| 138 | * radix_tree_deref_slot - dereference a slot |
| 139 | * @pslot: pointer to slot, returned by radix_tree_lookup_slot |
| 140 | * Returns: item that was stored in that slot with any direct pointer flag |
| 141 | * removed. |
| 142 | * |
| 143 | * For use with radix_tree_lookup_slot(). Caller must hold tree at least read |
Nick Piggin | 27d20fd | 2010-11-11 14:05:19 -0800 | [diff] [blame] | 144 | * locked across slot lookup and dereference. Not required if write lock is |
| 145 | * held (ie. items cannot be concurrently inserted). |
| 146 | * |
| 147 | * radix_tree_deref_retry must be used to confirm validity of the pointer if |
| 148 | * only the read lock is held. |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 149 | */ |
| 150 | static inline void *radix_tree_deref_slot(void **pslot) |
| 151 | { |
Nick Piggin | 27d20fd | 2010-11-11 14:05:19 -0800 | [diff] [blame] | 152 | return rcu_dereference(*pslot); |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 153 | } |
Nick Piggin | 27d20fd | 2010-11-11 14:05:19 -0800 | [diff] [blame] | 154 | |
| 155 | /** |
Mel Gorman | 29c1f67 | 2011-01-13 15:47:21 -0800 | [diff] [blame] | 156 | * radix_tree_deref_slot_protected - dereference a slot without RCU lock but with tree lock held |
| 157 | * @pslot: pointer to slot, returned by radix_tree_lookup_slot |
| 158 | * Returns: item that was stored in that slot with any direct pointer flag |
| 159 | * removed. |
| 160 | * |
| 161 | * Similar to radix_tree_deref_slot but only used during migration when a pages |
| 162 | * mapping is being moved. The caller does not hold the RCU read lock but it |
| 163 | * must hold the tree lock to prevent parallel updates. |
| 164 | */ |
| 165 | static inline void *radix_tree_deref_slot_protected(void **pslot, |
| 166 | spinlock_t *treelock) |
| 167 | { |
| 168 | return rcu_dereference_protected(*pslot, lockdep_is_held(treelock)); |
| 169 | } |
| 170 | |
| 171 | /** |
Nick Piggin | 27d20fd | 2010-11-11 14:05:19 -0800 | [diff] [blame] | 172 | * radix_tree_deref_retry - check radix_tree_deref_slot |
| 173 | * @arg: pointer returned by radix_tree_deref_slot |
| 174 | * Returns: 0 if retry is not required, otherwise retry is required |
| 175 | * |
| 176 | * radix_tree_deref_retry must be used with radix_tree_deref_slot. |
| 177 | */ |
| 178 | static inline int radix_tree_deref_retry(void *arg) |
| 179 | { |
| 180 | return unlikely((unsigned long)arg & RADIX_TREE_INDIRECT_PTR); |
| 181 | } |
| 182 | |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 183 | /** |
Hugh Dickins | 6328650 | 2011-08-03 16:21:18 -0700 | [diff] [blame] | 184 | * radix_tree_exceptional_entry - radix_tree_deref_slot gave exceptional entry? |
| 185 | * @arg: value returned by radix_tree_deref_slot |
| 186 | * Returns: 0 if well-aligned pointer, non-0 if exceptional entry. |
| 187 | */ |
| 188 | static inline int radix_tree_exceptional_entry(void *arg) |
| 189 | { |
| 190 | /* Not unlikely because radix_tree_exception often tested first */ |
| 191 | return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY; |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * radix_tree_exception - radix_tree_deref_slot returned either exception? |
| 196 | * @arg: value returned by radix_tree_deref_slot |
| 197 | * Returns: 0 if well-aligned pointer, non-0 if either kind of exception. |
| 198 | */ |
| 199 | static inline int radix_tree_exception(void *arg) |
| 200 | { |
| 201 | return unlikely((unsigned long)arg & |
| 202 | (RADIX_TREE_INDIRECT_PTR | RADIX_TREE_EXCEPTIONAL_ENTRY)); |
| 203 | } |
| 204 | |
| 205 | /** |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 206 | * radix_tree_replace_slot - replace item in a slot |
| 207 | * @pslot: pointer to slot, returned by radix_tree_lookup_slot |
| 208 | * @item: new item to store in the slot. |
| 209 | * |
| 210 | * For use with radix_tree_lookup_slot(). Caller must hold tree write locked |
| 211 | * across slot lookup and replacement. |
| 212 | */ |
| 213 | static inline void radix_tree_replace_slot(void **pslot, void *item) |
| 214 | { |
Nick Piggin | c0bc987 | 2007-10-16 01:24:42 -0700 | [diff] [blame] | 215 | BUG_ON(radix_tree_is_indirect_ptr(item)); |
| 216 | rcu_assign_pointer(*pslot, item); |
Nick Piggin | 7cf9c2c | 2006-12-06 20:33:44 -0800 | [diff] [blame] | 217 | } |
| 218 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | int radix_tree_insert(struct radix_tree_root *, unsigned long, void *); |
| 220 | void *radix_tree_lookup(struct radix_tree_root *, unsigned long); |
Hans Reiser | a433136 | 2005-11-07 00:59:29 -0800 | [diff] [blame] | 221 | void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | void *radix_tree_delete(struct radix_tree_root *, unsigned long); |
| 223 | unsigned int |
| 224 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, |
| 225 | unsigned long first_index, unsigned int max_items); |
Hugh Dickins | 6328650 | 2011-08-03 16:21:18 -0700 | [diff] [blame] | 226 | unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root, |
| 227 | void ***results, unsigned long *indices, |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 228 | unsigned long first_index, unsigned int max_items); |
Fengguang Wu | 6df8ba4 | 2007-10-16 01:24:33 -0700 | [diff] [blame] | 229 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, |
| 230 | unsigned long index, unsigned long max_scan); |
Wu Fengguang | dc56612 | 2009-06-16 15:31:32 -0700 | [diff] [blame] | 231 | unsigned long radix_tree_prev_hole(struct radix_tree_root *root, |
| 232 | unsigned long index, unsigned long max_scan); |
Al Viro | dd0fc66 | 2005-10-07 07:46:04 +0100 | [diff] [blame] | 233 | int radix_tree_preload(gfp_t gfp_mask); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 234 | void radix_tree_init(void); |
| 235 | void *radix_tree_tag_set(struct radix_tree_root *root, |
Jonathan Corbet | daff89f | 2006-03-25 03:08:05 -0800 | [diff] [blame] | 236 | unsigned long index, unsigned int tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | void *radix_tree_tag_clear(struct radix_tree_root *root, |
Jonathan Corbet | daff89f | 2006-03-25 03:08:05 -0800 | [diff] [blame] | 238 | unsigned long index, unsigned int tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | int radix_tree_tag_get(struct radix_tree_root *root, |
Jonathan Corbet | daff89f | 2006-03-25 03:08:05 -0800 | [diff] [blame] | 240 | unsigned long index, unsigned int tag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 241 | unsigned int |
| 242 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, |
Jonathan Corbet | daff89f | 2006-03-25 03:08:05 -0800 | [diff] [blame] | 243 | unsigned long first_index, unsigned int max_items, |
| 244 | unsigned int tag); |
Nick Piggin | 47feff2 | 2008-07-25 19:45:29 -0700 | [diff] [blame] | 245 | unsigned int |
| 246 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, |
| 247 | unsigned long first_index, unsigned int max_items, |
| 248 | unsigned int tag); |
Jan Kara | ebf8aa4 | 2010-08-09 17:19:11 -0700 | [diff] [blame] | 249 | unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, |
| 250 | unsigned long *first_indexp, unsigned long last_index, |
| 251 | unsigned long nr_to_tag, |
| 252 | unsigned int fromtag, unsigned int totag); |
Jonathan Corbet | daff89f | 2006-03-25 03:08:05 -0800 | [diff] [blame] | 253 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag); |
Hugh Dickins | e504f3f | 2011-08-03 16:21:27 -0700 | [diff] [blame] | 254 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 255 | |
| 256 | static inline void radix_tree_preload_end(void) |
| 257 | { |
| 258 | preempt_enable(); |
| 259 | } |
| 260 | |
Konstantin Khlebnikov | 78c1d78 | 2012-03-28 14:42:53 -0700 | [diff] [blame] | 261 | /** |
| 262 | * struct radix_tree_iter - radix tree iterator state |
| 263 | * |
| 264 | * @index: index of current slot |
| 265 | * @next_index: next-to-last index for this chunk |
| 266 | * @tags: bit-mask for tag-iterating |
| 267 | * |
| 268 | * This radix tree iterator works in terms of "chunks" of slots. A chunk is a |
| 269 | * subinterval of slots contained within one radix tree leaf node. It is |
| 270 | * described by a pointer to its first slot and a struct radix_tree_iter |
| 271 | * which holds the chunk's position in the tree and its size. For tagged |
| 272 | * iteration radix_tree_iter also holds the slots' bit-mask for one chosen |
| 273 | * radix tree tag. |
| 274 | */ |
| 275 | struct radix_tree_iter { |
| 276 | unsigned long index; |
| 277 | unsigned long next_index; |
| 278 | unsigned long tags; |
| 279 | }; |
| 280 | |
| 281 | #define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */ |
| 282 | #define RADIX_TREE_ITER_TAGGED 0x0100 /* lookup tagged slots */ |
| 283 | #define RADIX_TREE_ITER_CONTIG 0x0200 /* stop at first hole */ |
| 284 | |
| 285 | /** |
| 286 | * radix_tree_iter_init - initialize radix tree iterator |
| 287 | * |
| 288 | * @iter: pointer to iterator state |
| 289 | * @start: iteration starting index |
| 290 | * Returns: NULL |
| 291 | */ |
| 292 | static __always_inline void ** |
| 293 | radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start) |
| 294 | { |
| 295 | /* |
| 296 | * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it |
| 297 | * in the case of a successful tagged chunk lookup. If the lookup was |
| 298 | * unsuccessful or non-tagged then nobody cares about ->tags. |
| 299 | * |
| 300 | * Set index to zero to bypass next_index overflow protection. |
| 301 | * See the comment in radix_tree_next_chunk() for details. |
| 302 | */ |
| 303 | iter->index = 0; |
| 304 | iter->next_index = start; |
| 305 | return NULL; |
| 306 | } |
| 307 | |
| 308 | /** |
| 309 | * radix_tree_next_chunk - find next chunk of slots for iteration |
| 310 | * |
| 311 | * @root: radix tree root |
| 312 | * @iter: iterator state |
| 313 | * @flags: RADIX_TREE_ITER_* flags and tag index |
| 314 | * Returns: pointer to chunk first slot, or NULL if there no more left |
| 315 | * |
| 316 | * This function looks up the next chunk in the radix tree starting from |
| 317 | * @iter->next_index. It returns a pointer to the chunk's first slot. |
| 318 | * Also it fills @iter with data about chunk: position in the tree (index), |
| 319 | * its end (next_index), and constructs a bit mask for tagged iterating (tags). |
| 320 | */ |
| 321 | void **radix_tree_next_chunk(struct radix_tree_root *root, |
| 322 | struct radix_tree_iter *iter, unsigned flags); |
| 323 | |
| 324 | /** |
| 325 | * radix_tree_chunk_size - get current chunk size |
| 326 | * |
| 327 | * @iter: pointer to radix tree iterator |
| 328 | * Returns: current chunk size |
| 329 | */ |
| 330 | static __always_inline unsigned |
| 331 | radix_tree_chunk_size(struct radix_tree_iter *iter) |
| 332 | { |
| 333 | return iter->next_index - iter->index; |
| 334 | } |
| 335 | |
| 336 | /** |
| 337 | * radix_tree_next_slot - find next slot in chunk |
| 338 | * |
| 339 | * @slot: pointer to current slot |
| 340 | * @iter: pointer to interator state |
| 341 | * @flags: RADIX_TREE_ITER_*, should be constant |
| 342 | * Returns: pointer to next slot, or NULL if there no more left |
| 343 | * |
| 344 | * This function updates @iter->index in the case of a successful lookup. |
| 345 | * For tagged lookup it also eats @iter->tags. |
| 346 | */ |
| 347 | static __always_inline void ** |
| 348 | radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) |
| 349 | { |
| 350 | if (flags & RADIX_TREE_ITER_TAGGED) { |
| 351 | iter->tags >>= 1; |
| 352 | if (likely(iter->tags & 1ul)) { |
| 353 | iter->index++; |
| 354 | return slot + 1; |
| 355 | } |
| 356 | if (!(flags & RADIX_TREE_ITER_CONTIG) && likely(iter->tags)) { |
| 357 | unsigned offset = __ffs(iter->tags); |
| 358 | |
| 359 | iter->tags >>= offset; |
| 360 | iter->index += offset + 1; |
| 361 | return slot + offset + 1; |
| 362 | } |
| 363 | } else { |
| 364 | unsigned size = radix_tree_chunk_size(iter) - 1; |
| 365 | |
| 366 | while (size--) { |
| 367 | slot++; |
| 368 | iter->index++; |
| 369 | if (likely(*slot)) |
| 370 | return slot; |
| 371 | if (flags & RADIX_TREE_ITER_CONTIG) |
| 372 | break; |
| 373 | } |
| 374 | } |
| 375 | return NULL; |
| 376 | } |
| 377 | |
| 378 | /** |
| 379 | * radix_tree_for_each_chunk - iterate over chunks |
| 380 | * |
| 381 | * @slot: the void** variable for pointer to chunk first slot |
| 382 | * @root: the struct radix_tree_root pointer |
| 383 | * @iter: the struct radix_tree_iter pointer |
| 384 | * @start: iteration starting index |
| 385 | * @flags: RADIX_TREE_ITER_* and tag index |
| 386 | * |
| 387 | * Locks can be released and reacquired between iterations. |
| 388 | */ |
| 389 | #define radix_tree_for_each_chunk(slot, root, iter, start, flags) \ |
| 390 | for (slot = radix_tree_iter_init(iter, start) ; \ |
| 391 | (slot = radix_tree_next_chunk(root, iter, flags)) ;) |
| 392 | |
| 393 | /** |
| 394 | * radix_tree_for_each_chunk_slot - iterate over slots in one chunk |
| 395 | * |
| 396 | * @slot: the void** variable, at the beginning points to chunk first slot |
| 397 | * @iter: the struct radix_tree_iter pointer |
| 398 | * @flags: RADIX_TREE_ITER_*, should be constant |
| 399 | * |
| 400 | * This macro is designed to be nested inside radix_tree_for_each_chunk(). |
| 401 | * @slot points to the radix tree slot, @iter->index contains its index. |
| 402 | */ |
| 403 | #define radix_tree_for_each_chunk_slot(slot, iter, flags) \ |
| 404 | for (; slot ; slot = radix_tree_next_slot(slot, iter, flags)) |
| 405 | |
| 406 | /** |
| 407 | * radix_tree_for_each_slot - iterate over non-empty slots |
| 408 | * |
| 409 | * @slot: the void** variable for pointer to slot |
| 410 | * @root: the struct radix_tree_root pointer |
| 411 | * @iter: the struct radix_tree_iter pointer |
| 412 | * @start: iteration starting index |
| 413 | * |
| 414 | * @slot points to radix tree slot, @iter->index contains its index. |
| 415 | */ |
| 416 | #define radix_tree_for_each_slot(slot, root, iter, start) \ |
| 417 | for (slot = radix_tree_iter_init(iter, start) ; \ |
| 418 | slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \ |
| 419 | slot = radix_tree_next_slot(slot, iter, 0)) |
| 420 | |
| 421 | /** |
| 422 | * radix_tree_for_each_contig - iterate over contiguous slots |
| 423 | * |
| 424 | * @slot: the void** variable for pointer to slot |
| 425 | * @root: the struct radix_tree_root pointer |
| 426 | * @iter: the struct radix_tree_iter pointer |
| 427 | * @start: iteration starting index |
| 428 | * |
| 429 | * @slot points to radix tree slot, @iter->index contains its index. |
| 430 | */ |
| 431 | #define radix_tree_for_each_contig(slot, root, iter, start) \ |
| 432 | for (slot = radix_tree_iter_init(iter, start) ; \ |
| 433 | slot || (slot = radix_tree_next_chunk(root, iter, \ |
| 434 | RADIX_TREE_ITER_CONTIG)) ; \ |
| 435 | slot = radix_tree_next_slot(slot, iter, \ |
| 436 | RADIX_TREE_ITER_CONTIG)) |
| 437 | |
| 438 | /** |
| 439 | * radix_tree_for_each_tagged - iterate over tagged slots |
| 440 | * |
| 441 | * @slot: the void** variable for pointer to slot |
| 442 | * @root: the struct radix_tree_root pointer |
| 443 | * @iter: the struct radix_tree_iter pointer |
| 444 | * @start: iteration starting index |
| 445 | * @tag: tag index |
| 446 | * |
| 447 | * @slot points to radix tree slot, @iter->index contains its index. |
| 448 | */ |
| 449 | #define radix_tree_for_each_tagged(slot, root, iter, start, tag) \ |
| 450 | for (slot = radix_tree_iter_init(iter, start) ; \ |
| 451 | slot || (slot = radix_tree_next_chunk(root, iter, \ |
| 452 | RADIX_TREE_ITER_TAGGED | tag)) ; \ |
| 453 | slot = radix_tree_next_slot(slot, iter, \ |
| 454 | RADIX_TREE_ITER_TAGGED)) |
| 455 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 456 | #endif /* _LINUX_RADIX_TREE_H */ |