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1 : : // SPDX-License-Identifier: GPL-2.0-or-later
2 : : /* Generic associative array implementation.
3 : : *
4 : : * See Documentation/core-api/assoc_array.rst for information.
5 : : *
6 : : * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
7 : : * Written by David Howells (dhowells@redhat.com)
8 : : */
9 : : //#define DEBUG
10 : : #include <linux/rcupdate.h>
11 : : #include <linux/slab.h>
12 : : #include <linux/err.h>
13 : : #include <linux/assoc_array_priv.h>
14 : :
15 : : /*
16 : : * Iterate over an associative array. The caller must hold the RCU read lock
17 : : * or better.
18 : : */
19 : 0 : static int assoc_array_subtree_iterate(const struct assoc_array_ptr *root,
20 : : const struct assoc_array_ptr *stop,
21 : : int (*iterator)(const void *leaf,
22 : : void *iterator_data),
23 : : void *iterator_data)
24 : : {
25 : 0 : const struct assoc_array_shortcut *shortcut;
26 : 0 : const struct assoc_array_node *node;
27 : 0 : const struct assoc_array_ptr *cursor, *ptr, *parent;
28 : 0 : unsigned long has_meta;
29 : 0 : int slot, ret;
30 : :
31 : 0 : cursor = root;
32 : :
33 : 0 : begin_node:
34 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(cursor)) {
35 : : /* Descend through a shortcut */
36 : 0 : shortcut = assoc_array_ptr_to_shortcut(cursor);
37 : 0 : cursor = READ_ONCE(shortcut->next_node); /* Address dependency. */
38 : : }
39 : :
40 : 0 : node = assoc_array_ptr_to_node(cursor);
41 : 0 : slot = 0;
42 : :
43 : : /* We perform two passes of each node.
44 : : *
45 : : * The first pass does all the leaves in this node. This means we
46 : : * don't miss any leaves if the node is split up by insertion whilst
47 : : * we're iterating over the branches rooted here (we may, however, see
48 : : * some leaves twice).
49 : : */
50 : 0 : has_meta = 0;
51 [ # # ]: 0 : for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
52 [ # # ]: 0 : ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */
53 : 0 : has_meta |= (unsigned long)ptr;
54 [ # # # # ]: 0 : if (ptr && assoc_array_ptr_is_leaf(ptr)) {
55 : : /* We need a barrier between the read of the pointer,
56 : : * which is supplied by the above READ_ONCE().
57 : : */
58 : : /* Invoke the callback */
59 : 0 : ret = iterator(assoc_array_ptr_to_leaf(ptr),
60 : : iterator_data);
61 [ # # ]: 0 : if (ret)
62 : 0 : return ret;
63 : : }
64 : : }
65 : :
66 : : /* The second pass attends to all the metadata pointers. If we follow
67 : : * one of these we may find that we don't come back here, but rather go
68 : : * back to a replacement node with the leaves in a different layout.
69 : : *
70 : : * We are guaranteed to make progress, however, as the slot number for
71 : : * a particular portion of the key space cannot change - and we
72 : : * continue at the back pointer + 1.
73 : : */
74 [ # # ]: 0 : if (!(has_meta & ASSOC_ARRAY_PTR_META_TYPE))
75 : 0 : goto finished_node;
76 : : slot = 0;
77 : :
78 : 0 : continue_node:
79 : 0 : node = assoc_array_ptr_to_node(cursor);
80 [ # # ]: 0 : for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
81 [ # # ]: 0 : ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */
82 [ # # ]: 0 : if (assoc_array_ptr_is_meta(ptr)) {
83 : 0 : cursor = ptr;
84 : 0 : goto begin_node;
85 : : }
86 : : }
87 : :
88 : 0 : finished_node:
89 : : /* Move up to the parent (may need to skip back over a shortcut) */
90 [ # # ]: 0 : parent = READ_ONCE(node->back_pointer); /* Address dependency. */
91 : 0 : slot = node->parent_slot;
92 [ # # ]: 0 : if (parent == stop)
93 : : return 0;
94 : :
95 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(parent)) {
96 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(parent);
97 : 0 : cursor = parent;
98 [ # # ]: 0 : parent = READ_ONCE(shortcut->back_pointer); /* Address dependency. */
99 : 0 : slot = shortcut->parent_slot;
100 [ # # ]: 0 : if (parent == stop)
101 : : return 0;
102 : : }
103 : :
104 : : /* Ascend to next slot in parent node */
105 : 0 : cursor = parent;
106 : 0 : slot++;
107 : 0 : goto continue_node;
108 : : }
109 : :
110 : : /**
111 : : * assoc_array_iterate - Pass all objects in the array to a callback
112 : : * @array: The array to iterate over.
113 : : * @iterator: The callback function.
114 : : * @iterator_data: Private data for the callback function.
115 : : *
116 : : * Iterate over all the objects in an associative array. Each one will be
117 : : * presented to the iterator function.
118 : : *
119 : : * If the array is being modified concurrently with the iteration then it is
120 : : * possible that some objects in the array will be passed to the iterator
121 : : * callback more than once - though every object should be passed at least
122 : : * once. If this is undesirable then the caller must lock against modification
123 : : * for the duration of this function.
124 : : *
125 : : * The function will return 0 if no objects were in the array or else it will
126 : : * return the result of the last iterator function called. Iteration stops
127 : : * immediately if any call to the iteration function results in a non-zero
128 : : * return.
129 : : *
130 : : * The caller should hold the RCU read lock or better if concurrent
131 : : * modification is possible.
132 : : */
133 : 0 : int assoc_array_iterate(const struct assoc_array *array,
134 : : int (*iterator)(const void *object,
135 : : void *iterator_data),
136 : : void *iterator_data)
137 : : {
138 [ # # ]: 0 : struct assoc_array_ptr *root = READ_ONCE(array->root); /* Address dependency. */
139 : :
140 [ # # ]: 0 : if (!root)
141 : : return 0;
142 : 0 : return assoc_array_subtree_iterate(root, NULL, iterator, iterator_data);
143 : : }
144 : :
145 : : enum assoc_array_walk_status {
146 : : assoc_array_walk_tree_empty,
147 : : assoc_array_walk_found_terminal_node,
148 : : assoc_array_walk_found_wrong_shortcut,
149 : : };
150 : :
151 : : struct assoc_array_walk_result {
152 : : struct {
153 : : struct assoc_array_node *node; /* Node in which leaf might be found */
154 : : int level;
155 : : int slot;
156 : : } terminal_node;
157 : : struct {
158 : : struct assoc_array_shortcut *shortcut;
159 : : int level;
160 : : int sc_level;
161 : : unsigned long sc_segments;
162 : : unsigned long dissimilarity;
163 : : } wrong_shortcut;
164 : : };
165 : :
166 : : /*
167 : : * Navigate through the internal tree looking for the closest node to the key.
168 : : */
169 : : static enum assoc_array_walk_status
170 : : assoc_array_walk(const struct assoc_array *array,
171 : : const struct assoc_array_ops *ops,
172 : : const void *index_key,
173 : : struct assoc_array_walk_result *result)
174 : : {
175 : : struct assoc_array_shortcut *shortcut;
176 : : struct assoc_array_node *node;
177 : : struct assoc_array_ptr *cursor, *ptr;
178 : : unsigned long sc_segments, dissimilarity;
179 : : unsigned long segments;
180 : : int level, sc_level, next_sc_level;
181 : : int slot;
182 : :
183 : : pr_devel("-->%s()\n", __func__);
184 : :
185 : : cursor = READ_ONCE(array->root); /* Address dependency. */
186 : : if (!cursor)
187 : : return assoc_array_walk_tree_empty;
188 : :
189 : : level = 0;
190 : :
191 : : /* Use segments from the key for the new leaf to navigate through the
192 : : * internal tree, skipping through nodes and shortcuts that are on
193 : : * route to the destination. Eventually we'll come to a slot that is
194 : : * either empty or contains a leaf at which point we've found a node in
195 : : * which the leaf we're looking for might be found or into which it
196 : : * should be inserted.
197 : : */
198 : : jumped:
199 : : segments = ops->get_key_chunk(index_key, level);
200 : : pr_devel("segments[%d]: %lx\n", level, segments);
201 : :
202 : : if (assoc_array_ptr_is_shortcut(cursor))
203 : : goto follow_shortcut;
204 : :
205 : : consider_node:
206 : : node = assoc_array_ptr_to_node(cursor);
207 : : slot = segments >> (level & ASSOC_ARRAY_KEY_CHUNK_MASK);
208 : : slot &= ASSOC_ARRAY_FAN_MASK;
209 : : ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */
210 : :
211 : : pr_devel("consider slot %x [ix=%d type=%lu]\n",
212 : : slot, level, (unsigned long)ptr & 3);
213 : :
214 : : if (!assoc_array_ptr_is_meta(ptr)) {
215 : : /* The node doesn't have a node/shortcut pointer in the slot
216 : : * corresponding to the index key that we have to follow.
217 : : */
218 : : result->terminal_node.node = node;
219 : : result->terminal_node.level = level;
220 : : result->terminal_node.slot = slot;
221 : : pr_devel("<--%s() = terminal_node\n", __func__);
222 : : return assoc_array_walk_found_terminal_node;
223 : : }
224 : :
225 : : if (assoc_array_ptr_is_node(ptr)) {
226 : : /* There is a pointer to a node in the slot corresponding to
227 : : * this index key segment, so we need to follow it.
228 : : */
229 : : cursor = ptr;
230 : : level += ASSOC_ARRAY_LEVEL_STEP;
231 : : if ((level & ASSOC_ARRAY_KEY_CHUNK_MASK) != 0)
232 : : goto consider_node;
233 : : goto jumped;
234 : : }
235 : :
236 : : /* There is a shortcut in the slot corresponding to the index key
237 : : * segment. We follow the shortcut if its partial index key matches
238 : : * this leaf's. Otherwise we need to split the shortcut.
239 : : */
240 : : cursor = ptr;
241 : : follow_shortcut:
242 : : shortcut = assoc_array_ptr_to_shortcut(cursor);
243 : : pr_devel("shortcut to %d\n", shortcut->skip_to_level);
244 : : sc_level = level + ASSOC_ARRAY_LEVEL_STEP;
245 : : BUG_ON(sc_level > shortcut->skip_to_level);
246 : :
247 : : do {
248 : : /* Check the leaf against the shortcut's index key a word at a
249 : : * time, trimming the final word (the shortcut stores the index
250 : : * key completely from the root to the shortcut's target).
251 : : */
252 : : if ((sc_level & ASSOC_ARRAY_KEY_CHUNK_MASK) == 0)
253 : : segments = ops->get_key_chunk(index_key, sc_level);
254 : :
255 : : sc_segments = shortcut->index_key[sc_level >> ASSOC_ARRAY_KEY_CHUNK_SHIFT];
256 : : dissimilarity = segments ^ sc_segments;
257 : :
258 : : if (round_up(sc_level, ASSOC_ARRAY_KEY_CHUNK_SIZE) > shortcut->skip_to_level) {
259 : : /* Trim segments that are beyond the shortcut */
260 : : int shift = shortcut->skip_to_level & ASSOC_ARRAY_KEY_CHUNK_MASK;
261 : : dissimilarity &= ~(ULONG_MAX << shift);
262 : : next_sc_level = shortcut->skip_to_level;
263 : : } else {
264 : : next_sc_level = sc_level + ASSOC_ARRAY_KEY_CHUNK_SIZE;
265 : : next_sc_level = round_down(next_sc_level, ASSOC_ARRAY_KEY_CHUNK_SIZE);
266 : : }
267 : :
268 : : if (dissimilarity != 0) {
269 : : /* This shortcut points elsewhere */
270 : : result->wrong_shortcut.shortcut = shortcut;
271 : : result->wrong_shortcut.level = level;
272 : : result->wrong_shortcut.sc_level = sc_level;
273 : : result->wrong_shortcut.sc_segments = sc_segments;
274 : : result->wrong_shortcut.dissimilarity = dissimilarity;
275 : : return assoc_array_walk_found_wrong_shortcut;
276 : : }
277 : :
278 : : sc_level = next_sc_level;
279 : : } while (sc_level < shortcut->skip_to_level);
280 : :
281 : : /* The shortcut matches the leaf's index to this point. */
282 : : cursor = READ_ONCE(shortcut->next_node); /* Address dependency. */
283 : : if (((level ^ sc_level) & ~ASSOC_ARRAY_KEY_CHUNK_MASK) != 0) {
284 : : level = sc_level;
285 : : goto jumped;
286 : : } else {
287 : : level = sc_level;
288 : : goto consider_node;
289 : : }
290 : : }
291 : :
292 : : /**
293 : : * assoc_array_find - Find an object by index key
294 : : * @array: The associative array to search.
295 : : * @ops: The operations to use.
296 : : * @index_key: The key to the object.
297 : : *
298 : : * Find an object in an associative array by walking through the internal tree
299 : : * to the node that should contain the object and then searching the leaves
300 : : * there. NULL is returned if the requested object was not found in the array.
301 : : *
302 : : * The caller must hold the RCU read lock or better.
303 : : */
304 : 1596 : void *assoc_array_find(const struct assoc_array *array,
305 : : const struct assoc_array_ops *ops,
306 : : const void *index_key)
307 : : {
308 : 1596 : struct assoc_array_walk_result result;
309 : 1596 : const struct assoc_array_node *node;
310 : 1596 : const struct assoc_array_ptr *ptr;
311 : 1596 : const void *leaf;
312 : 1596 : int slot;
313 : :
314 [ + + ]: 1596 : if (assoc_array_walk(array, ops, index_key, &result) !=
315 : : assoc_array_walk_found_terminal_node)
316 : : return NULL;
317 : :
318 : 945 : node = result.terminal_node.node;
319 : :
320 : : /* If the target key is available to us, it's has to be pointed to by
321 : : * the terminal node.
322 : : */
323 [ + + ]: 6447 : for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
324 [ + + ]: 6300 : ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */
325 [ + + + - ]: 6300 : if (ptr && assoc_array_ptr_is_leaf(ptr)) {
326 : : /* We need a barrier between the read of the pointer
327 : : * and dereferencing the pointer - but only if we are
328 : : * actually going to dereference it.
329 : : */
330 : 1155 : leaf = assoc_array_ptr_to_leaf(ptr);
331 [ + + ]: 1155 : if (ops->compare_object(leaf, index_key))
332 : 798 : return (void *)leaf;
333 : : }
334 : : }
335 : :
336 : : return NULL;
337 : : }
338 : :
339 : : /*
340 : : * Destructively iterate over an associative array. The caller must prevent
341 : : * other simultaneous accesses.
342 : : */
343 : 441 : static void assoc_array_destroy_subtree(struct assoc_array_ptr *root,
344 : : const struct assoc_array_ops *ops)
345 : : {
346 : 441 : struct assoc_array_shortcut *shortcut;
347 : 441 : struct assoc_array_node *node;
348 : 441 : struct assoc_array_ptr *cursor, *parent = NULL;
349 : 441 : int slot = -1;
350 : :
351 : 441 : pr_devel("-->%s()\n", __func__);
352 : :
353 : 441 : cursor = root;
354 [ + - ]: 441 : if (!cursor) {
355 : : pr_devel("empty\n");
356 : : return;
357 : : }
358 : :
359 : 441 : move_to_meta:
360 [ - + ]: 441 : if (assoc_array_ptr_is_shortcut(cursor)) {
361 : : /* Descend through a shortcut */
362 : 0 : pr_devel("[%d] shortcut\n", slot);
363 [ # # ]: 0 : BUG_ON(!assoc_array_ptr_is_shortcut(cursor));
364 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(cursor);
365 [ # # ]: 0 : BUG_ON(shortcut->back_pointer != parent);
366 [ # # # # ]: 0 : BUG_ON(slot != -1 && shortcut->parent_slot != slot);
367 : 0 : parent = cursor;
368 : 0 : cursor = shortcut->next_node;
369 : 0 : slot = -1;
370 [ # # ]: 0 : BUG_ON(!assoc_array_ptr_is_node(cursor));
371 : : }
372 : :
373 : 441 : pr_devel("[%d] node\n", slot);
374 [ - + ]: 441 : node = assoc_array_ptr_to_node(cursor);
375 [ - + ]: 441 : BUG_ON(node->back_pointer != parent);
376 [ - + - - ]: 441 : BUG_ON(slot != -1 && node->parent_slot != slot);
377 : : slot = 0;
378 : :
379 : : continue_node:
380 : 441 : pr_devel("Node %p [back=%p]\n", node, node->back_pointer);
381 [ + + ]: 7497 : for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
382 : 7056 : struct assoc_array_ptr *ptr = node->slots[slot];
383 [ + + ]: 7056 : if (!ptr)
384 : 6510 : continue;
385 [ - + ]: 546 : if (assoc_array_ptr_is_meta(ptr)) {
386 : 0 : parent = cursor;
387 : 0 : cursor = ptr;
388 : 0 : goto move_to_meta;
389 : : }
390 : :
391 [ + - ]: 546 : if (ops) {
392 : 546 : pr_devel("[%d] free leaf\n", slot);
393 : 546 : ops->free_object(assoc_array_ptr_to_leaf(ptr));
394 : : }
395 : : }
396 : :
397 : 441 : parent = node->back_pointer;
398 : 441 : slot = node->parent_slot;
399 : 441 : pr_devel("free node\n");
400 : 441 : kfree(node);
401 [ - + ]: 441 : if (!parent)
402 : : return; /* Done */
403 : :
404 : : /* Move back up to the parent (may need to free a shortcut on
405 : : * the way up) */
406 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(parent)) {
407 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(parent);
408 [ # # ]: 0 : BUG_ON(shortcut->next_node != cursor);
409 : 0 : cursor = parent;
410 : 0 : parent = shortcut->back_pointer;
411 : 0 : slot = shortcut->parent_slot;
412 : 0 : pr_devel("free shortcut\n");
413 : 0 : kfree(shortcut);
414 [ # # ]: 0 : if (!parent)
415 : : return;
416 : :
417 [ # # ]: 0 : BUG_ON(!assoc_array_ptr_is_node(parent));
418 : : }
419 : :
420 : : /* Ascend to next slot in parent node */
421 : 0 : pr_devel("ascend to %p[%d]\n", parent, slot);
422 : 0 : cursor = parent;
423 : 0 : node = assoc_array_ptr_to_node(cursor);
424 : 0 : slot++;
425 : 0 : goto continue_node;
426 : : }
427 : :
428 : : /**
429 : : * assoc_array_destroy - Destroy an associative array
430 : : * @array: The array to destroy.
431 : : * @ops: The operations to use.
432 : : *
433 : : * Discard all metadata and free all objects in an associative array. The
434 : : * array will be empty and ready to use again upon completion. This function
435 : : * cannot fail.
436 : : *
437 : : * The caller must prevent all other accesses whilst this takes place as no
438 : : * attempt is made to adjust pointers gracefully to permit RCU readlock-holding
439 : : * accesses to continue. On the other hand, no memory allocation is required.
440 : : */
441 : 441 : void assoc_array_destroy(struct assoc_array *array,
442 : : const struct assoc_array_ops *ops)
443 : : {
444 : 441 : assoc_array_destroy_subtree(array->root, ops);
445 : 441 : array->root = NULL;
446 : 441 : }
447 : :
448 : : /*
449 : : * Handle insertion into an empty tree.
450 : : */
451 : 651 : static bool assoc_array_insert_in_empty_tree(struct assoc_array_edit *edit)
452 : : {
453 : 651 : struct assoc_array_node *new_n0;
454 : :
455 : 651 : pr_devel("-->%s()\n", __func__);
456 : :
457 : 651 : new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
458 [ + - ]: 651 : if (!new_n0)
459 : : return false;
460 : :
461 : 651 : edit->new_meta[0] = assoc_array_node_to_ptr(new_n0);
462 : 651 : edit->leaf_p = &new_n0->slots[0];
463 : 651 : edit->adjust_count_on = new_n0;
464 : 651 : edit->set[0].ptr = &edit->array->root;
465 : 651 : edit->set[0].to = assoc_array_node_to_ptr(new_n0);
466 : :
467 : 651 : pr_devel("<--%s() = ok [no root]\n", __func__);
468 : 651 : return true;
469 : : }
470 : :
471 : : /*
472 : : * Handle insertion into a terminal node.
473 : : */
474 : 126 : static bool assoc_array_insert_into_terminal_node(struct assoc_array_edit *edit,
475 : : const struct assoc_array_ops *ops,
476 : : const void *index_key,
477 : : struct assoc_array_walk_result *result)
478 : : {
479 : 126 : struct assoc_array_shortcut *shortcut, *new_s0;
480 : 126 : struct assoc_array_node *node, *new_n0, *new_n1, *side;
481 : 126 : struct assoc_array_ptr *ptr;
482 : 126 : unsigned long dissimilarity, base_seg, blank;
483 : 126 : size_t keylen;
484 : 126 : bool have_meta;
485 : 126 : int level, diff;
486 : 126 : int slot, next_slot, free_slot, i, j;
487 : :
488 : 126 : node = result->terminal_node.node;
489 : 126 : level = result->terminal_node.level;
490 : 126 : edit->segment_cache[ASSOC_ARRAY_FAN_OUT] = result->terminal_node.slot;
491 : :
492 : 126 : pr_devel("-->%s()\n", __func__);
493 : :
494 : : /* We arrived at a node which doesn't have an onward node or shortcut
495 : : * pointer that we have to follow. This means that (a) the leaf we
496 : : * want must go here (either by insertion or replacement) or (b) we
497 : : * need to split this node and insert in one of the fragments.
498 : : */
499 : 126 : free_slot = -1;
500 : :
501 : : /* Firstly, we have to check the leaves in this node to see if there's
502 : : * a matching one we should replace in place.
503 : : */
504 [ + + ]: 2142 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
505 : 2016 : ptr = node->slots[i];
506 [ + + ]: 2016 : if (!ptr) {
507 : 1890 : free_slot = i;
508 : 1890 : continue;
509 : : }
510 [ + - - + ]: 252 : if (assoc_array_ptr_is_leaf(ptr) &&
511 : 126 : ops->compare_object(assoc_array_ptr_to_leaf(ptr),
512 : : index_key)) {
513 : 0 : pr_devel("replace in slot %d\n", i);
514 : 0 : edit->leaf_p = &node->slots[i];
515 : 0 : edit->dead_leaf = node->slots[i];
516 : 0 : pr_devel("<--%s() = ok [replace]\n", __func__);
517 : 0 : return true;
518 : : }
519 : : }
520 : :
521 : : /* If there is a free slot in this node then we can just insert the
522 : : * leaf here.
523 : : */
524 [ + - ]: 126 : if (free_slot >= 0) {
525 : 126 : pr_devel("insert in free slot %d\n", free_slot);
526 : 126 : edit->leaf_p = &node->slots[free_slot];
527 : 126 : edit->adjust_count_on = node;
528 : 126 : pr_devel("<--%s() = ok [insert]\n", __func__);
529 : 126 : return true;
530 : : }
531 : :
532 : : /* The node has no spare slots - so we're either going to have to split
533 : : * it or insert another node before it.
534 : : *
535 : : * Whatever, we're going to need at least two new nodes - so allocate
536 : : * those now. We may also need a new shortcut, but we deal with that
537 : : * when we need it.
538 : : */
539 : 0 : new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
540 [ # # ]: 0 : if (!new_n0)
541 : : return false;
542 : 0 : edit->new_meta[0] = assoc_array_node_to_ptr(new_n0);
543 : 0 : new_n1 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
544 [ # # ]: 0 : if (!new_n1)
545 : : return false;
546 : 0 : edit->new_meta[1] = assoc_array_node_to_ptr(new_n1);
547 : :
548 : : /* We need to find out how similar the leaves are. */
549 : 0 : pr_devel("no spare slots\n");
550 : 0 : have_meta = false;
551 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
552 : 0 : ptr = node->slots[i];
553 [ # # ]: 0 : if (assoc_array_ptr_is_meta(ptr)) {
554 : 0 : edit->segment_cache[i] = 0xff;
555 : 0 : have_meta = true;
556 : 0 : continue;
557 : : }
558 : 0 : base_seg = ops->get_object_key_chunk(
559 : : assoc_array_ptr_to_leaf(ptr), level);
560 : 0 : base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK;
561 : 0 : edit->segment_cache[i] = base_seg & ASSOC_ARRAY_FAN_MASK;
562 : : }
563 : :
564 [ # # ]: 0 : if (have_meta) {
565 : 0 : pr_devel("have meta\n");
566 : 0 : goto split_node;
567 : : }
568 : :
569 : : /* The node contains only leaves */
570 : 0 : dissimilarity = 0;
571 : 0 : base_seg = edit->segment_cache[0];
572 [ # # ]: 0 : for (i = 1; i < ASSOC_ARRAY_FAN_OUT; i++)
573 : 0 : dissimilarity |= edit->segment_cache[i] ^ base_seg;
574 : :
575 : 0 : pr_devel("only leaves; dissimilarity=%lx\n", dissimilarity);
576 : :
577 [ # # ]: 0 : if ((dissimilarity & ASSOC_ARRAY_FAN_MASK) == 0) {
578 : : /* The old leaves all cluster in the same slot. We will need
579 : : * to insert a shortcut if the new node wants to cluster with them.
580 : : */
581 [ # # ]: 0 : if ((edit->segment_cache[ASSOC_ARRAY_FAN_OUT] ^ base_seg) == 0)
582 : 0 : goto all_leaves_cluster_together;
583 : :
584 : : /* Otherwise all the old leaves cluster in the same slot, but
585 : : * the new leaf wants to go into a different slot - so we
586 : : * create a new node (n0) to hold the new leaf and a pointer to
587 : : * a new node (n1) holding all the old leaves.
588 : : *
589 : : * This can be done by falling through to the node splitting
590 : : * path.
591 : : */
592 : : pr_devel("present leaves cluster but not new leaf\n");
593 : : }
594 : :
595 : 0 : split_node:
596 : 0 : pr_devel("split node\n");
597 : :
598 : : /* We need to split the current node. The node must contain anything
599 : : * from a single leaf (in the one leaf case, this leaf will cluster
600 : : * with the new leaf) and the rest meta-pointers, to all leaves, some
601 : : * of which may cluster.
602 : : *
603 : : * It won't contain the case in which all the current leaves plus the
604 : : * new leaves want to cluster in the same slot.
605 : : *
606 : : * We need to expel at least two leaves out of a set consisting of the
607 : : * leaves in the node and the new leaf. The current meta pointers can
608 : : * just be copied as they shouldn't cluster with any of the leaves.
609 : : *
610 : : * We need a new node (n0) to replace the current one and a new node to
611 : : * take the expelled nodes (n1).
612 : : */
613 : 0 : edit->set[0].to = assoc_array_node_to_ptr(new_n0);
614 : 0 : new_n0->back_pointer = node->back_pointer;
615 : 0 : new_n0->parent_slot = node->parent_slot;
616 : 0 : new_n1->back_pointer = assoc_array_node_to_ptr(new_n0);
617 : 0 : new_n1->parent_slot = -1; /* Need to calculate this */
618 : :
619 : 0 : do_split_node:
620 : 0 : pr_devel("do_split_node\n");
621 : :
622 : 0 : new_n0->nr_leaves_on_branch = node->nr_leaves_on_branch;
623 : 0 : new_n1->nr_leaves_on_branch = 0;
624 : :
625 : : /* Begin by finding two matching leaves. There have to be at least two
626 : : * that match - even if there are meta pointers - because any leaf that
627 : : * would match a slot with a meta pointer in it must be somewhere
628 : : * behind that meta pointer and cannot be here. Further, given N
629 : : * remaining leaf slots, we now have N+1 leaves to go in them.
630 : : */
631 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
632 : 0 : slot = edit->segment_cache[i];
633 [ # # ]: 0 : if (slot != 0xff)
634 [ # # ]: 0 : for (j = i + 1; j < ASSOC_ARRAY_FAN_OUT + 1; j++)
635 [ # # ]: 0 : if (edit->segment_cache[j] == slot)
636 : 0 : goto found_slot_for_multiple_occupancy;
637 : : }
638 : 0 : found_slot_for_multiple_occupancy:
639 : 0 : pr_devel("same slot: %x %x [%02x]\n", i, j, slot);
640 [ # # ]: 0 : BUG_ON(i >= ASSOC_ARRAY_FAN_OUT);
641 [ # # ]: 0 : BUG_ON(j >= ASSOC_ARRAY_FAN_OUT + 1);
642 [ # # ]: 0 : BUG_ON(slot >= ASSOC_ARRAY_FAN_OUT);
643 : :
644 : 0 : new_n1->parent_slot = slot;
645 : :
646 : : /* Metadata pointers cannot change slot */
647 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++)
648 [ # # ]: 0 : if (assoc_array_ptr_is_meta(node->slots[i]))
649 : 0 : new_n0->slots[i] = node->slots[i];
650 : : else
651 : 0 : new_n0->slots[i] = NULL;
652 [ # # ]: 0 : BUG_ON(new_n0->slots[slot] != NULL);
653 : 0 : new_n0->slots[slot] = assoc_array_node_to_ptr(new_n1);
654 : :
655 : : /* Filter the leaf pointers between the new nodes */
656 : 0 : free_slot = -1;
657 : 0 : next_slot = 0;
658 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
659 [ # # ]: 0 : if (assoc_array_ptr_is_meta(node->slots[i]))
660 : 0 : continue;
661 [ # # ]: 0 : if (edit->segment_cache[i] == slot) {
662 : 0 : new_n1->slots[next_slot++] = node->slots[i];
663 : 0 : new_n1->nr_leaves_on_branch++;
664 : : } else {
665 : 0 : do {
666 : 0 : free_slot++;
667 [ # # ]: 0 : } while (new_n0->slots[free_slot] != NULL);
668 : 0 : new_n0->slots[free_slot] = node->slots[i];
669 : : }
670 : : }
671 : :
672 : 0 : pr_devel("filtered: f=%x n=%x\n", free_slot, next_slot);
673 : :
674 [ # # ]: 0 : if (edit->segment_cache[ASSOC_ARRAY_FAN_OUT] != slot) {
675 : 0 : do {
676 : 0 : free_slot++;
677 [ # # ]: 0 : } while (new_n0->slots[free_slot] != NULL);
678 : 0 : edit->leaf_p = &new_n0->slots[free_slot];
679 : 0 : edit->adjust_count_on = new_n0;
680 : : } else {
681 : 0 : edit->leaf_p = &new_n1->slots[next_slot++];
682 : 0 : edit->adjust_count_on = new_n1;
683 : : }
684 : :
685 [ # # ]: 0 : BUG_ON(next_slot <= 1);
686 : :
687 : 0 : edit->set_backpointers_to = assoc_array_node_to_ptr(new_n0);
688 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
689 [ # # ]: 0 : if (edit->segment_cache[i] == 0xff) {
690 : 0 : ptr = node->slots[i];
691 [ # # ]: 0 : BUG_ON(assoc_array_ptr_is_leaf(ptr));
692 [ # # ]: 0 : if (assoc_array_ptr_is_node(ptr)) {
693 : 0 : side = assoc_array_ptr_to_node(ptr);
694 : 0 : edit->set_backpointers[i] = &side->back_pointer;
695 : : } else {
696 : 0 : shortcut = assoc_array_ptr_to_shortcut(ptr);
697 : 0 : edit->set_backpointers[i] = &shortcut->back_pointer;
698 : : }
699 : : }
700 : : }
701 : :
702 : 0 : ptr = node->back_pointer;
703 [ # # ]: 0 : if (!ptr)
704 : 0 : edit->set[0].ptr = &edit->array->root;
705 [ # # ]: 0 : else if (assoc_array_ptr_is_node(ptr))
706 : 0 : edit->set[0].ptr = &assoc_array_ptr_to_node(ptr)->slots[node->parent_slot];
707 : : else
708 : 0 : edit->set[0].ptr = &assoc_array_ptr_to_shortcut(ptr)->next_node;
709 : 0 : edit->excised_meta[0] = assoc_array_node_to_ptr(node);
710 : 0 : pr_devel("<--%s() = ok [split node]\n", __func__);
711 : 0 : return true;
712 : :
713 : : all_leaves_cluster_together:
714 : : /* All the leaves, new and old, want to cluster together in this node
715 : : * in the same slot, so we have to replace this node with a shortcut to
716 : : * skip over the identical parts of the key and then place a pair of
717 : : * nodes, one inside the other, at the end of the shortcut and
718 : : * distribute the keys between them.
719 : : *
720 : : * Firstly we need to work out where the leaves start diverging as a
721 : : * bit position into their keys so that we know how big the shortcut
722 : : * needs to be.
723 : : *
724 : : * We only need to make a single pass of N of the N+1 leaves because if
725 : : * any keys differ between themselves at bit X then at least one of
726 : : * them must also differ with the base key at bit X or before.
727 : : */
728 : 0 : pr_devel("all leaves cluster together\n");
729 : 0 : diff = INT_MAX;
730 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
731 : 0 : int x = ops->diff_objects(assoc_array_ptr_to_leaf(node->slots[i]),
732 : : index_key);
733 [ # # ]: 0 : if (x < diff) {
734 [ # # ]: 0 : BUG_ON(x < 0);
735 : : diff = x;
736 : : }
737 : : }
738 [ # # ]: 0 : BUG_ON(diff == INT_MAX);
739 [ # # ]: 0 : BUG_ON(diff < level + ASSOC_ARRAY_LEVEL_STEP);
740 : :
741 : 0 : keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE);
742 : 0 : keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
743 : :
744 : 0 : new_s0 = kzalloc(sizeof(struct assoc_array_shortcut) +
745 : : keylen * sizeof(unsigned long), GFP_KERNEL);
746 [ # # ]: 0 : if (!new_s0)
747 : : return false;
748 [ # # ]: 0 : edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s0);
749 : :
750 : 0 : edit->set[0].to = assoc_array_shortcut_to_ptr(new_s0);
751 : 0 : new_s0->back_pointer = node->back_pointer;
752 : 0 : new_s0->parent_slot = node->parent_slot;
753 [ # # ]: 0 : new_s0->next_node = assoc_array_node_to_ptr(new_n0);
754 : 0 : new_n0->back_pointer = assoc_array_shortcut_to_ptr(new_s0);
755 : 0 : new_n0->parent_slot = 0;
756 : 0 : new_n1->back_pointer = assoc_array_node_to_ptr(new_n0);
757 : 0 : new_n1->parent_slot = -1; /* Need to calculate this */
758 : :
759 : 0 : new_s0->skip_to_level = level = diff & ~ASSOC_ARRAY_LEVEL_STEP_MASK;
760 : 0 : pr_devel("skip_to_level = %d [diff %d]\n", level, diff);
761 [ # # ]: 0 : BUG_ON(level <= 0);
762 : :
763 [ # # ]: 0 : for (i = 0; i < keylen; i++)
764 : 0 : new_s0->index_key[i] =
765 : 0 : ops->get_key_chunk(index_key, i * ASSOC_ARRAY_KEY_CHUNK_SIZE);
766 : :
767 [ # # ]: 0 : if (level & ASSOC_ARRAY_KEY_CHUNK_MASK) {
768 : 0 : blank = ULONG_MAX << (level & ASSOC_ARRAY_KEY_CHUNK_MASK);
769 : 0 : pr_devel("blank off [%zu] %d: %lx\n", keylen - 1, level, blank);
770 : 0 : new_s0->index_key[keylen - 1] &= ~blank;
771 : : }
772 : :
773 : : /* This now reduces to a node splitting exercise for which we'll need
774 : : * to regenerate the disparity table.
775 : : */
776 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
777 : 0 : ptr = node->slots[i];
778 : 0 : base_seg = ops->get_object_key_chunk(assoc_array_ptr_to_leaf(ptr),
779 : : level);
780 : 0 : base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK;
781 : 0 : edit->segment_cache[i] = base_seg & ASSOC_ARRAY_FAN_MASK;
782 : : }
783 : :
784 : 0 : base_seg = ops->get_key_chunk(index_key, level);
785 : 0 : base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK;
786 : 0 : edit->segment_cache[ASSOC_ARRAY_FAN_OUT] = base_seg & ASSOC_ARRAY_FAN_MASK;
787 : 0 : goto do_split_node;
788 : : }
789 : :
790 : : /*
791 : : * Handle insertion into the middle of a shortcut.
792 : : */
793 : : static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit,
794 : : const struct assoc_array_ops *ops,
795 : : struct assoc_array_walk_result *result)
796 : : {
797 : : struct assoc_array_shortcut *shortcut, *new_s0, *new_s1;
798 : : struct assoc_array_node *node, *new_n0, *side;
799 : : unsigned long sc_segments, dissimilarity, blank;
800 : : size_t keylen;
801 : : int level, sc_level, diff;
802 : : int sc_slot;
803 : :
804 : : shortcut = result->wrong_shortcut.shortcut;
805 : : level = result->wrong_shortcut.level;
806 : : sc_level = result->wrong_shortcut.sc_level;
807 : : sc_segments = result->wrong_shortcut.sc_segments;
808 : : dissimilarity = result->wrong_shortcut.dissimilarity;
809 : :
810 : : pr_devel("-->%s(ix=%d dis=%lx scix=%d)\n",
811 : : __func__, level, dissimilarity, sc_level);
812 : :
813 : : /* We need to split a shortcut and insert a node between the two
814 : : * pieces. Zero-length pieces will be dispensed with entirely.
815 : : *
816 : : * First of all, we need to find out in which level the first
817 : : * difference was.
818 : : */
819 : : diff = __ffs(dissimilarity);
820 : : diff &= ~ASSOC_ARRAY_LEVEL_STEP_MASK;
821 : : diff += sc_level & ~ASSOC_ARRAY_KEY_CHUNK_MASK;
822 : : pr_devel("diff=%d\n", diff);
823 : :
824 : : if (!shortcut->back_pointer) {
825 : : edit->set[0].ptr = &edit->array->root;
826 : : } else if (assoc_array_ptr_is_node(shortcut->back_pointer)) {
827 : : node = assoc_array_ptr_to_node(shortcut->back_pointer);
828 : : edit->set[0].ptr = &node->slots[shortcut->parent_slot];
829 : : } else {
830 : : BUG();
831 : : }
832 : :
833 : : edit->excised_meta[0] = assoc_array_shortcut_to_ptr(shortcut);
834 : :
835 : : /* Create a new node now since we're going to need it anyway */
836 : : new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
837 : : if (!new_n0)
838 : : return false;
839 : : edit->new_meta[0] = assoc_array_node_to_ptr(new_n0);
840 : : edit->adjust_count_on = new_n0;
841 : :
842 : : /* Insert a new shortcut before the new node if this segment isn't of
843 : : * zero length - otherwise we just connect the new node directly to the
844 : : * parent.
845 : : */
846 : : level += ASSOC_ARRAY_LEVEL_STEP;
847 : : if (diff > level) {
848 : : pr_devel("pre-shortcut %d...%d\n", level, diff);
849 : : keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE);
850 : : keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
851 : :
852 : : new_s0 = kzalloc(sizeof(struct assoc_array_shortcut) +
853 : : keylen * sizeof(unsigned long), GFP_KERNEL);
854 : : if (!new_s0)
855 : : return false;
856 : : edit->new_meta[1] = assoc_array_shortcut_to_ptr(new_s0);
857 : : edit->set[0].to = assoc_array_shortcut_to_ptr(new_s0);
858 : : new_s0->back_pointer = shortcut->back_pointer;
859 : : new_s0->parent_slot = shortcut->parent_slot;
860 : : new_s0->next_node = assoc_array_node_to_ptr(new_n0);
861 : : new_s0->skip_to_level = diff;
862 : :
863 : : new_n0->back_pointer = assoc_array_shortcut_to_ptr(new_s0);
864 : : new_n0->parent_slot = 0;
865 : :
866 : : memcpy(new_s0->index_key, shortcut->index_key,
867 : : keylen * sizeof(unsigned long));
868 : :
869 : : blank = ULONG_MAX << (diff & ASSOC_ARRAY_KEY_CHUNK_MASK);
870 : : pr_devel("blank off [%zu] %d: %lx\n", keylen - 1, diff, blank);
871 : : new_s0->index_key[keylen - 1] &= ~blank;
872 : : } else {
873 : : pr_devel("no pre-shortcut\n");
874 : : edit->set[0].to = assoc_array_node_to_ptr(new_n0);
875 : : new_n0->back_pointer = shortcut->back_pointer;
876 : : new_n0->parent_slot = shortcut->parent_slot;
877 : : }
878 : :
879 : : side = assoc_array_ptr_to_node(shortcut->next_node);
880 : : new_n0->nr_leaves_on_branch = side->nr_leaves_on_branch;
881 : :
882 : : /* We need to know which slot in the new node is going to take a
883 : : * metadata pointer.
884 : : */
885 : : sc_slot = sc_segments >> (diff & ASSOC_ARRAY_KEY_CHUNK_MASK);
886 : : sc_slot &= ASSOC_ARRAY_FAN_MASK;
887 : :
888 : : pr_devel("new slot %lx >> %d -> %d\n",
889 : : sc_segments, diff & ASSOC_ARRAY_KEY_CHUNK_MASK, sc_slot);
890 : :
891 : : /* Determine whether we need to follow the new node with a replacement
892 : : * for the current shortcut. We could in theory reuse the current
893 : : * shortcut if its parent slot number doesn't change - but that's a
894 : : * 1-in-16 chance so not worth expending the code upon.
895 : : */
896 : : level = diff + ASSOC_ARRAY_LEVEL_STEP;
897 : : if (level < shortcut->skip_to_level) {
898 : : pr_devel("post-shortcut %d...%d\n", level, shortcut->skip_to_level);
899 : : keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE);
900 : : keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
901 : :
902 : : new_s1 = kzalloc(sizeof(struct assoc_array_shortcut) +
903 : : keylen * sizeof(unsigned long), GFP_KERNEL);
904 : : if (!new_s1)
905 : : return false;
906 : : edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s1);
907 : :
908 : : new_s1->back_pointer = assoc_array_node_to_ptr(new_n0);
909 : : new_s1->parent_slot = sc_slot;
910 : : new_s1->next_node = shortcut->next_node;
911 : : new_s1->skip_to_level = shortcut->skip_to_level;
912 : :
913 : : new_n0->slots[sc_slot] = assoc_array_shortcut_to_ptr(new_s1);
914 : :
915 : : memcpy(new_s1->index_key, shortcut->index_key,
916 : : keylen * sizeof(unsigned long));
917 : :
918 : : edit->set[1].ptr = &side->back_pointer;
919 : : edit->set[1].to = assoc_array_shortcut_to_ptr(new_s1);
920 : : } else {
921 : : pr_devel("no post-shortcut\n");
922 : :
923 : : /* We don't have to replace the pointed-to node as long as we
924 : : * use memory barriers to make sure the parent slot number is
925 : : * changed before the back pointer (the parent slot number is
926 : : * irrelevant to the old parent shortcut).
927 : : */
928 : : new_n0->slots[sc_slot] = shortcut->next_node;
929 : : edit->set_parent_slot[0].p = &side->parent_slot;
930 : : edit->set_parent_slot[0].to = sc_slot;
931 : : edit->set[1].ptr = &side->back_pointer;
932 : : edit->set[1].to = assoc_array_node_to_ptr(new_n0);
933 : : }
934 : :
935 : : /* Install the new leaf in a spare slot in the new node. */
936 : : if (sc_slot == 0)
937 : : edit->leaf_p = &new_n0->slots[1];
938 : : else
939 : : edit->leaf_p = &new_n0->slots[0];
940 : :
941 : : pr_devel("<--%s() = ok [split shortcut]\n", __func__);
942 : : return edit;
943 : : }
944 : :
945 : : /**
946 : : * assoc_array_insert - Script insertion of an object into an associative array
947 : : * @array: The array to insert into.
948 : : * @ops: The operations to use.
949 : : * @index_key: The key to insert at.
950 : : * @object: The object to insert.
951 : : *
952 : : * Precalculate and preallocate a script for the insertion or replacement of an
953 : : * object in an associative array. This results in an edit script that can
954 : : * either be applied or cancelled.
955 : : *
956 : : * The function returns a pointer to an edit script or -ENOMEM.
957 : : *
958 : : * The caller should lock against other modifications and must continue to hold
959 : : * the lock until assoc_array_apply_edit() has been called.
960 : : *
961 : : * Accesses to the tree may take place concurrently with this function,
962 : : * provided they hold the RCU read lock.
963 : : */
964 : 777 : struct assoc_array_edit *assoc_array_insert(struct assoc_array *array,
965 : : const struct assoc_array_ops *ops,
966 : : const void *index_key,
967 : : void *object)
968 : : {
969 : 777 : struct assoc_array_walk_result result;
970 : 777 : struct assoc_array_edit *edit;
971 : :
972 : 777 : pr_devel("-->%s()\n", __func__);
973 : :
974 : : /* The leaf pointer we're given must not have the bottom bit set as we
975 : : * use those for type-marking the pointer. NULL pointers are also not
976 : : * allowed as they indicate an empty slot but we have to allow them
977 : : * here as they can be updated later.
978 : : */
979 [ - + ]: 777 : BUG_ON(assoc_array_ptr_is_meta(object));
980 : :
981 : 777 : edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL);
982 [ + - ]: 777 : if (!edit)
983 : : return ERR_PTR(-ENOMEM);
984 : 777 : edit->array = array;
985 : 777 : edit->ops = ops;
986 : 777 : edit->leaf = assoc_array_leaf_to_ptr(object);
987 : 777 : edit->adjust_count_by = 1;
988 : :
989 [ + + - - ]: 777 : switch (assoc_array_walk(array, ops, index_key, &result)) {
990 : 651 : case assoc_array_walk_tree_empty:
991 : : /* Allocate a root node if there isn't one yet */
992 [ - + ]: 651 : if (!assoc_array_insert_in_empty_tree(edit))
993 : 0 : goto enomem;
994 : : return edit;
995 : :
996 : 126 : case assoc_array_walk_found_terminal_node:
997 : : /* We found a node that doesn't have a node/shortcut pointer in
998 : : * the slot corresponding to the index key that we have to
999 : : * follow.
1000 : : */
1001 [ - + ]: 126 : if (!assoc_array_insert_into_terminal_node(edit, ops, index_key,
1002 : : &result))
1003 : 0 : goto enomem;
1004 : : return edit;
1005 : :
1006 : 0 : case assoc_array_walk_found_wrong_shortcut:
1007 : : /* We found a shortcut that didn't match our key in a slot we
1008 : : * needed to follow.
1009 : : */
1010 [ # # ]: 0 : if (!assoc_array_insert_mid_shortcut(edit, ops, &result))
1011 : 0 : goto enomem;
1012 : : return edit;
1013 : : }
1014 : :
1015 : 0 : enomem:
1016 : : /* Clean up after an out of memory error */
1017 : 0 : pr_devel("enomem\n");
1018 : 0 : assoc_array_cancel_edit(edit);
1019 : 0 : return ERR_PTR(-ENOMEM);
1020 : : }
1021 : :
1022 : : /**
1023 : : * assoc_array_insert_set_object - Set the new object pointer in an edit script
1024 : : * @edit: The edit script to modify.
1025 : : * @object: The object pointer to set.
1026 : : *
1027 : : * Change the object to be inserted in an edit script. The object pointed to
1028 : : * by the old object is not freed. This must be done prior to applying the
1029 : : * script.
1030 : : */
1031 : 777 : void assoc_array_insert_set_object(struct assoc_array_edit *edit, void *object)
1032 : : {
1033 [ - + ]: 777 : BUG_ON(!object);
1034 : 777 : edit->leaf = assoc_array_leaf_to_ptr(object);
1035 : 777 : }
1036 : :
1037 : : struct assoc_array_delete_collapse_context {
1038 : : struct assoc_array_node *node;
1039 : : const void *skip_leaf;
1040 : : int slot;
1041 : : };
1042 : :
1043 : : /*
1044 : : * Subtree collapse to node iterator.
1045 : : */
1046 : 0 : static int assoc_array_delete_collapse_iterator(const void *leaf,
1047 : : void *iterator_data)
1048 : : {
1049 : 0 : struct assoc_array_delete_collapse_context *collapse = iterator_data;
1050 : :
1051 [ # # ]: 0 : if (leaf == collapse->skip_leaf)
1052 : : return 0;
1053 : :
1054 [ # # ]: 0 : BUG_ON(collapse->slot >= ASSOC_ARRAY_FAN_OUT);
1055 : :
1056 : 0 : collapse->node->slots[collapse->slot++] = assoc_array_leaf_to_ptr(leaf);
1057 : 0 : return 0;
1058 : : }
1059 : :
1060 : : /**
1061 : : * assoc_array_delete - Script deletion of an object from an associative array
1062 : : * @array: The array to search.
1063 : : * @ops: The operations to use.
1064 : : * @index_key: The key to the object.
1065 : : *
1066 : : * Precalculate and preallocate a script for the deletion of an object from an
1067 : : * associative array. This results in an edit script that can either be
1068 : : * applied or cancelled.
1069 : : *
1070 : : * The function returns a pointer to an edit script if the object was found,
1071 : : * NULL if the object was not found or -ENOMEM.
1072 : : *
1073 : : * The caller should lock against other modifications and must continue to hold
1074 : : * the lock until assoc_array_apply_edit() has been called.
1075 : : *
1076 : : * Accesses to the tree may take place concurrently with this function,
1077 : : * provided they hold the RCU read lock.
1078 : : */
1079 : 0 : struct assoc_array_edit *assoc_array_delete(struct assoc_array *array,
1080 : : const struct assoc_array_ops *ops,
1081 : : const void *index_key)
1082 : : {
1083 : 0 : struct assoc_array_delete_collapse_context collapse;
1084 : 0 : struct assoc_array_walk_result result;
1085 : 0 : struct assoc_array_node *node, *new_n0;
1086 : 0 : struct assoc_array_edit *edit;
1087 : 0 : struct assoc_array_ptr *ptr;
1088 : 0 : bool has_meta;
1089 : 0 : int slot, i;
1090 : :
1091 : 0 : pr_devel("-->%s()\n", __func__);
1092 : :
1093 : 0 : edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL);
1094 [ # # ]: 0 : if (!edit)
1095 : : return ERR_PTR(-ENOMEM);
1096 : 0 : edit->array = array;
1097 : 0 : edit->ops = ops;
1098 : 0 : edit->adjust_count_by = -1;
1099 : :
1100 [ # # ]: 0 : switch (assoc_array_walk(array, ops, index_key, &result)) {
1101 : : case assoc_array_walk_found_terminal_node:
1102 : : /* We found a node that should contain the leaf we've been
1103 : : * asked to remove - *if* it's in the tree.
1104 : : */
1105 : 0 : pr_devel("terminal_node\n");
1106 : 0 : node = result.terminal_node.node;
1107 : :
1108 [ # # ]: 0 : for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
1109 : 0 : ptr = node->slots[slot];
1110 [ # # # # ]: 0 : if (ptr &&
1111 [ # # ]: 0 : assoc_array_ptr_is_leaf(ptr) &&
1112 : 0 : ops->compare_object(assoc_array_ptr_to_leaf(ptr),
1113 : : index_key))
1114 : 0 : goto found_leaf;
1115 : : }
1116 : : /* fall through */
1117 : : case assoc_array_walk_tree_empty:
1118 : : case assoc_array_walk_found_wrong_shortcut:
1119 : : default:
1120 : 0 : assoc_array_cancel_edit(edit);
1121 : 0 : pr_devel("not found\n");
1122 : 0 : return NULL;
1123 : : }
1124 : :
1125 : : found_leaf:
1126 [ # # ]: 0 : BUG_ON(array->nr_leaves_on_tree <= 0);
1127 : :
1128 : : /* In the simplest form of deletion we just clear the slot and release
1129 : : * the leaf after a suitable interval.
1130 : : */
1131 : 0 : edit->dead_leaf = node->slots[slot];
1132 : 0 : edit->set[0].ptr = &node->slots[slot];
1133 : 0 : edit->set[0].to = NULL;
1134 : 0 : edit->adjust_count_on = node;
1135 : :
1136 : : /* If that concludes erasure of the last leaf, then delete the entire
1137 : : * internal array.
1138 : : */
1139 [ # # ]: 0 : if (array->nr_leaves_on_tree == 1) {
1140 : 0 : edit->set[1].ptr = &array->root;
1141 : 0 : edit->set[1].to = NULL;
1142 : 0 : edit->adjust_count_on = NULL;
1143 : 0 : edit->excised_subtree = array->root;
1144 : 0 : pr_devel("all gone\n");
1145 : 0 : return edit;
1146 : : }
1147 : :
1148 : : /* However, we'd also like to clear up some metadata blocks if we
1149 : : * possibly can.
1150 : : *
1151 : : * We go for a simple algorithm of: if this node has FAN_OUT or fewer
1152 : : * leaves in it, then attempt to collapse it - and attempt to
1153 : : * recursively collapse up the tree.
1154 : : *
1155 : : * We could also try and collapse in partially filled subtrees to take
1156 : : * up space in this node.
1157 : : */
1158 [ # # ]: 0 : if (node->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT + 1) {
1159 : : struct assoc_array_node *parent, *grandparent;
1160 : : struct assoc_array_ptr *ptr;
1161 : :
1162 : : /* First of all, we need to know if this node has metadata so
1163 : : * that we don't try collapsing if all the leaves are already
1164 : : * here.
1165 : : */
1166 : : has_meta = false;
1167 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
1168 : 0 : ptr = node->slots[i];
1169 [ # # ]: 0 : if (assoc_array_ptr_is_meta(ptr)) {
1170 : : has_meta = true;
1171 : : break;
1172 : : }
1173 : : }
1174 : :
1175 : 0 : pr_devel("leaves: %ld [m=%d]\n",
1176 : : node->nr_leaves_on_branch - 1, has_meta);
1177 : :
1178 : : /* Look further up the tree to see if we can collapse this node
1179 : : * into a more proximal node too.
1180 : : */
1181 : 0 : parent = node;
1182 : 0 : collapse_up:
1183 : 0 : pr_devel("collapse subtree: %ld\n", parent->nr_leaves_on_branch);
1184 : :
1185 : 0 : ptr = parent->back_pointer;
1186 [ # # ]: 0 : if (!ptr)
1187 : 0 : goto do_collapse;
1188 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(ptr)) {
1189 [ # # ]: 0 : struct assoc_array_shortcut *s = assoc_array_ptr_to_shortcut(ptr);
1190 : 0 : ptr = s->back_pointer;
1191 [ # # ]: 0 : if (!ptr)
1192 : 0 : goto do_collapse;
1193 : : }
1194 : :
1195 [ # # ]: 0 : grandparent = assoc_array_ptr_to_node(ptr);
1196 [ # # ]: 0 : if (grandparent->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT + 1) {
1197 : 0 : parent = grandparent;
1198 : 0 : goto collapse_up;
1199 : : }
1200 : :
1201 : 0 : do_collapse:
1202 : : /* There's no point collapsing if the original node has no meta
1203 : : * pointers to discard and if we didn't merge into one of that
1204 : : * node's ancestry.
1205 : : */
1206 [ # # ]: 0 : if (has_meta || parent != node) {
1207 : 0 : node = parent;
1208 : :
1209 : : /* Create a new node to collapse into */
1210 : 0 : new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
1211 [ # # ]: 0 : if (!new_n0)
1212 : 0 : goto enomem;
1213 : 0 : edit->new_meta[0] = assoc_array_node_to_ptr(new_n0);
1214 : :
1215 : 0 : new_n0->back_pointer = node->back_pointer;
1216 : 0 : new_n0->parent_slot = node->parent_slot;
1217 : 0 : new_n0->nr_leaves_on_branch = node->nr_leaves_on_branch;
1218 : 0 : edit->adjust_count_on = new_n0;
1219 : :
1220 : 0 : collapse.node = new_n0;
1221 : 0 : collapse.skip_leaf = assoc_array_ptr_to_leaf(edit->dead_leaf);
1222 : 0 : collapse.slot = 0;
1223 : 0 : assoc_array_subtree_iterate(assoc_array_node_to_ptr(node),
1224 : 0 : node->back_pointer,
1225 : : assoc_array_delete_collapse_iterator,
1226 : : &collapse);
1227 : 0 : pr_devel("collapsed %d,%lu\n", collapse.slot, new_n0->nr_leaves_on_branch);
1228 [ # # ]: 0 : BUG_ON(collapse.slot != new_n0->nr_leaves_on_branch - 1);
1229 : :
1230 [ # # ]: 0 : if (!node->back_pointer) {
1231 : 0 : edit->set[1].ptr = &array->root;
1232 [ # # ]: 0 : } else if (assoc_array_ptr_is_leaf(node->back_pointer)) {
1233 : 0 : BUG();
1234 [ # # ]: 0 : } else if (assoc_array_ptr_is_node(node->back_pointer)) {
1235 : 0 : struct assoc_array_node *p =
1236 : : assoc_array_ptr_to_node(node->back_pointer);
1237 : 0 : edit->set[1].ptr = &p->slots[node->parent_slot];
1238 : 0 : } else if (assoc_array_ptr_is_shortcut(node->back_pointer)) {
1239 : 0 : struct assoc_array_shortcut *s =
1240 : : assoc_array_ptr_to_shortcut(node->back_pointer);
1241 : 0 : edit->set[1].ptr = &s->next_node;
1242 : : }
1243 : 0 : edit->set[1].to = assoc_array_node_to_ptr(new_n0);
1244 : 0 : edit->excised_subtree = assoc_array_node_to_ptr(node);
1245 : : }
1246 : : }
1247 : :
1248 : : return edit;
1249 : :
1250 : : enomem:
1251 : : /* Clean up after an out of memory error */
1252 : 0 : pr_devel("enomem\n");
1253 : 0 : assoc_array_cancel_edit(edit);
1254 : 0 : return ERR_PTR(-ENOMEM);
1255 : : }
1256 : :
1257 : : /**
1258 : : * assoc_array_clear - Script deletion of all objects from an associative array
1259 : : * @array: The array to clear.
1260 : : * @ops: The operations to use.
1261 : : *
1262 : : * Precalculate and preallocate a script for the deletion of all the objects
1263 : : * from an associative array. This results in an edit script that can either
1264 : : * be applied or cancelled.
1265 : : *
1266 : : * The function returns a pointer to an edit script if there are objects to be
1267 : : * deleted, NULL if there are no objects in the array or -ENOMEM.
1268 : : *
1269 : : * The caller should lock against other modifications and must continue to hold
1270 : : * the lock until assoc_array_apply_edit() has been called.
1271 : : *
1272 : : * Accesses to the tree may take place concurrently with this function,
1273 : : * provided they hold the RCU read lock.
1274 : : */
1275 : 0 : struct assoc_array_edit *assoc_array_clear(struct assoc_array *array,
1276 : : const struct assoc_array_ops *ops)
1277 : : {
1278 : 0 : struct assoc_array_edit *edit;
1279 : :
1280 : 0 : pr_devel("-->%s()\n", __func__);
1281 : :
1282 [ # # ]: 0 : if (!array->root)
1283 : : return NULL;
1284 : :
1285 : 0 : edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL);
1286 [ # # ]: 0 : if (!edit)
1287 : : return ERR_PTR(-ENOMEM);
1288 : 0 : edit->array = array;
1289 : 0 : edit->ops = ops;
1290 : 0 : edit->set[1].ptr = &array->root;
1291 : 0 : edit->set[1].to = NULL;
1292 : 0 : edit->excised_subtree = array->root;
1293 : 0 : edit->ops_for_excised_subtree = ops;
1294 : 0 : pr_devel("all gone\n");
1295 : 0 : return edit;
1296 : : }
1297 : :
1298 : : /*
1299 : : * Handle the deferred destruction after an applied edit.
1300 : : */
1301 : 777 : static void assoc_array_rcu_cleanup(struct rcu_head *head)
1302 : : {
1303 : 777 : struct assoc_array_edit *edit =
1304 : 777 : container_of(head, struct assoc_array_edit, rcu);
1305 : 777 : int i;
1306 : :
1307 : 777 : pr_devel("-->%s()\n", __func__);
1308 : :
1309 [ - + ]: 777 : if (edit->dead_leaf)
1310 : 0 : edit->ops->free_object(assoc_array_ptr_to_leaf(edit->dead_leaf));
1311 [ + + ]: 1554 : for (i = 0; i < ARRAY_SIZE(edit->excised_meta); i++)
1312 [ - + ]: 777 : if (edit->excised_meta[i])
1313 : 0 : kfree(assoc_array_ptr_to_node(edit->excised_meta[i]));
1314 : :
1315 [ - + ]: 777 : if (edit->excised_subtree) {
1316 [ # # ]: 0 : BUG_ON(assoc_array_ptr_is_leaf(edit->excised_subtree));
1317 [ # # ]: 0 : if (assoc_array_ptr_is_node(edit->excised_subtree)) {
1318 : 0 : struct assoc_array_node *n =
1319 : : assoc_array_ptr_to_node(edit->excised_subtree);
1320 : 0 : n->back_pointer = NULL;
1321 : : } else {
1322 : 0 : struct assoc_array_shortcut *s =
1323 : : assoc_array_ptr_to_shortcut(edit->excised_subtree);
1324 : 0 : s->back_pointer = NULL;
1325 : : }
1326 : 0 : assoc_array_destroy_subtree(edit->excised_subtree,
1327 : : edit->ops_for_excised_subtree);
1328 : : }
1329 : :
1330 : 777 : kfree(edit);
1331 : 777 : }
1332 : :
1333 : : /**
1334 : : * assoc_array_apply_edit - Apply an edit script to an associative array
1335 : : * @edit: The script to apply.
1336 : : *
1337 : : * Apply an edit script to an associative array to effect an insertion,
1338 : : * deletion or clearance. As the edit script includes preallocated memory,
1339 : : * this is guaranteed not to fail.
1340 : : *
1341 : : * The edit script, dead objects and dead metadata will be scheduled for
1342 : : * destruction after an RCU grace period to permit those doing read-only
1343 : : * accesses on the array to continue to do so under the RCU read lock whilst
1344 : : * the edit is taking place.
1345 : : */
1346 : 777 : void assoc_array_apply_edit(struct assoc_array_edit *edit)
1347 : : {
1348 : 777 : struct assoc_array_shortcut *shortcut;
1349 : 777 : struct assoc_array_node *node;
1350 : 777 : struct assoc_array_ptr *ptr;
1351 : 777 : int i;
1352 : :
1353 : 777 : pr_devel("-->%s()\n", __func__);
1354 : :
1355 : 777 : smp_wmb();
1356 [ + - ]: 777 : if (edit->leaf_p)
1357 : 777 : *edit->leaf_p = edit->leaf;
1358 : :
1359 : 777 : smp_wmb();
1360 [ + + ]: 2331 : for (i = 0; i < ARRAY_SIZE(edit->set_parent_slot); i++)
1361 [ - + ]: 777 : if (edit->set_parent_slot[i].p)
1362 : 0 : *edit->set_parent_slot[i].p = edit->set_parent_slot[i].to;
1363 : :
1364 : 777 : smp_wmb();
1365 [ + + ]: 13986 : for (i = 0; i < ARRAY_SIZE(edit->set_backpointers); i++)
1366 [ - + ]: 12432 : if (edit->set_backpointers[i])
1367 : 0 : *edit->set_backpointers[i] = edit->set_backpointers_to;
1368 : :
1369 : 777 : smp_wmb();
1370 [ + + ]: 3108 : for (i = 0; i < ARRAY_SIZE(edit->set); i++)
1371 [ + + ]: 1554 : if (edit->set[i].ptr)
1372 : 651 : *edit->set[i].ptr = edit->set[i].to;
1373 : :
1374 [ - + ]: 777 : if (edit->array->root == NULL) {
1375 : 0 : edit->array->nr_leaves_on_tree = 0;
1376 [ + - ]: 777 : } else if (edit->adjust_count_on) {
1377 : : node = edit->adjust_count_on;
1378 : 0 : for (;;) {
1379 : 777 : node->nr_leaves_on_branch += edit->adjust_count_by;
1380 : :
1381 : 777 : ptr = node->back_pointer;
1382 [ - + ]: 777 : if (!ptr)
1383 : : break;
1384 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(ptr)) {
1385 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(ptr);
1386 : 0 : ptr = shortcut->back_pointer;
1387 [ # # ]: 0 : if (!ptr)
1388 : : break;
1389 : : }
1390 [ # # ]: 0 : BUG_ON(!assoc_array_ptr_is_node(ptr));
1391 : 0 : node = assoc_array_ptr_to_node(ptr);
1392 : : }
1393 : :
1394 : 777 : edit->array->nr_leaves_on_tree += edit->adjust_count_by;
1395 : : }
1396 : :
1397 : 777 : call_rcu(&edit->rcu, assoc_array_rcu_cleanup);
1398 : 777 : }
1399 : :
1400 : : /**
1401 : : * assoc_array_cancel_edit - Discard an edit script.
1402 : : * @edit: The script to discard.
1403 : : *
1404 : : * Free an edit script and all the preallocated data it holds without making
1405 : : * any changes to the associative array it was intended for.
1406 : : *
1407 : : * NOTE! In the case of an insertion script, this does _not_ release the leaf
1408 : : * that was to be inserted. That is left to the caller.
1409 : : */
1410 : 0 : void assoc_array_cancel_edit(struct assoc_array_edit *edit)
1411 : : {
1412 : 0 : struct assoc_array_ptr *ptr;
1413 : 0 : int i;
1414 : :
1415 : 0 : pr_devel("-->%s()\n", __func__);
1416 : :
1417 : : /* Clean up after an out of memory error */
1418 [ # # ]: 0 : for (i = 0; i < ARRAY_SIZE(edit->new_meta); i++) {
1419 : 0 : ptr = edit->new_meta[i];
1420 [ # # ]: 0 : if (ptr) {
1421 [ # # ]: 0 : if (assoc_array_ptr_is_node(ptr))
1422 : 0 : kfree(assoc_array_ptr_to_node(ptr));
1423 : : else
1424 : 0 : kfree(assoc_array_ptr_to_shortcut(ptr));
1425 : : }
1426 : : }
1427 : 0 : kfree(edit);
1428 : 0 : }
1429 : :
1430 : : /**
1431 : : * assoc_array_gc - Garbage collect an associative array.
1432 : : * @array: The array to clean.
1433 : : * @ops: The operations to use.
1434 : : * @iterator: A callback function to pass judgement on each object.
1435 : : * @iterator_data: Private data for the callback function.
1436 : : *
1437 : : * Collect garbage from an associative array and pack down the internal tree to
1438 : : * save memory.
1439 : : *
1440 : : * The iterator function is asked to pass judgement upon each object in the
1441 : : * array. If it returns false, the object is discard and if it returns true,
1442 : : * the object is kept. If it returns true, it must increment the object's
1443 : : * usage count (or whatever it needs to do to retain it) before returning.
1444 : : *
1445 : : * This function returns 0 if successful or -ENOMEM if out of memory. In the
1446 : : * latter case, the array is not changed.
1447 : : *
1448 : : * The caller should lock against other modifications and must continue to hold
1449 : : * the lock until assoc_array_apply_edit() has been called.
1450 : : *
1451 : : * Accesses to the tree may take place concurrently with this function,
1452 : : * provided they hold the RCU read lock.
1453 : : */
1454 : 0 : int assoc_array_gc(struct assoc_array *array,
1455 : : const struct assoc_array_ops *ops,
1456 : : bool (*iterator)(void *object, void *iterator_data),
1457 : : void *iterator_data)
1458 : : {
1459 : 0 : struct assoc_array_shortcut *shortcut, *new_s;
1460 : 0 : struct assoc_array_node *node, *new_n;
1461 : 0 : struct assoc_array_edit *edit;
1462 : 0 : struct assoc_array_ptr *cursor, *ptr;
1463 : 0 : struct assoc_array_ptr *new_root, *new_parent, **new_ptr_pp;
1464 : 0 : unsigned long nr_leaves_on_tree;
1465 : 0 : int keylen, slot, nr_free, next_slot, i;
1466 : :
1467 : 0 : pr_devel("-->%s()\n", __func__);
1468 : :
1469 [ # # ]: 0 : if (!array->root)
1470 : : return 0;
1471 : :
1472 : 0 : edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL);
1473 [ # # ]: 0 : if (!edit)
1474 : : return -ENOMEM;
1475 : 0 : edit->array = array;
1476 : 0 : edit->ops = ops;
1477 : 0 : edit->ops_for_excised_subtree = ops;
1478 : 0 : edit->set[0].ptr = &array->root;
1479 : 0 : edit->excised_subtree = array->root;
1480 : :
1481 : 0 : new_root = new_parent = NULL;
1482 : 0 : new_ptr_pp = &new_root;
1483 : 0 : cursor = array->root;
1484 : :
1485 : 0 : descend:
1486 : : /* If this point is a shortcut, then we need to duplicate it and
1487 : : * advance the target cursor.
1488 : : */
1489 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(cursor)) {
1490 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(cursor);
1491 : 0 : keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE);
1492 : 0 : keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT;
1493 [ # # ]: 0 : new_s = kmalloc(sizeof(struct assoc_array_shortcut) +
1494 : : keylen * sizeof(unsigned long), GFP_KERNEL);
1495 [ # # ]: 0 : if (!new_s)
1496 : 0 : goto enomem;
1497 : 0 : pr_devel("dup shortcut %p -> %p\n", shortcut, new_s);
1498 : 0 : memcpy(new_s, shortcut, (sizeof(struct assoc_array_shortcut) +
1499 : : keylen * sizeof(unsigned long)));
1500 : 0 : new_s->back_pointer = new_parent;
1501 : 0 : new_s->parent_slot = shortcut->parent_slot;
1502 : 0 : *new_ptr_pp = new_parent = assoc_array_shortcut_to_ptr(new_s);
1503 : 0 : new_ptr_pp = &new_s->next_node;
1504 : 0 : cursor = shortcut->next_node;
1505 : : }
1506 : :
1507 : : /* Duplicate the node at this position */
1508 : 0 : node = assoc_array_ptr_to_node(cursor);
1509 : 0 : new_n = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
1510 [ # # ]: 0 : if (!new_n)
1511 : 0 : goto enomem;
1512 : 0 : pr_devel("dup node %p -> %p\n", node, new_n);
1513 : 0 : new_n->back_pointer = new_parent;
1514 : 0 : new_n->parent_slot = node->parent_slot;
1515 : 0 : *new_ptr_pp = new_parent = assoc_array_node_to_ptr(new_n);
1516 : 0 : new_ptr_pp = NULL;
1517 : 0 : slot = 0;
1518 : :
1519 : : continue_node:
1520 : : /* Filter across any leaves and gc any subtrees */
1521 [ # # ]: 0 : for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
1522 : 0 : ptr = node->slots[slot];
1523 [ # # ]: 0 : if (!ptr)
1524 : 0 : continue;
1525 : :
1526 [ # # ]: 0 : if (assoc_array_ptr_is_leaf(ptr)) {
1527 [ # # ]: 0 : if (iterator(assoc_array_ptr_to_leaf(ptr),
1528 : : iterator_data))
1529 : : /* The iterator will have done any reference
1530 : : * counting on the object for us.
1531 : : */
1532 : 0 : new_n->slots[slot] = ptr;
1533 : 0 : continue;
1534 : : }
1535 : :
1536 : 0 : new_ptr_pp = &new_n->slots[slot];
1537 : 0 : cursor = ptr;
1538 : 0 : goto descend;
1539 : : }
1540 : :
1541 : 0 : pr_devel("-- compress node %p --\n", new_n);
1542 : :
1543 : : /* Count up the number of empty slots in this node and work out the
1544 : : * subtree leaf count.
1545 : : */
1546 : 0 : new_n->nr_leaves_on_branch = 0;
1547 : 0 : nr_free = 0;
1548 [ # # ]: 0 : for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
1549 : 0 : ptr = new_n->slots[slot];
1550 [ # # ]: 0 : if (!ptr)
1551 : 0 : nr_free++;
1552 [ # # ]: 0 : else if (assoc_array_ptr_is_leaf(ptr))
1553 : 0 : new_n->nr_leaves_on_branch++;
1554 : : }
1555 : : pr_devel("free=%d, leaves=%lu\n", nr_free, new_n->nr_leaves_on_branch);
1556 : :
1557 : : /* See what we can fold in */
1558 : : next_slot = 0;
1559 [ # # ]: 0 : for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
1560 : 0 : struct assoc_array_shortcut *s;
1561 : 0 : struct assoc_array_node *child;
1562 : :
1563 : 0 : ptr = new_n->slots[slot];
1564 [ # # # # ]: 0 : if (!ptr || assoc_array_ptr_is_leaf(ptr))
1565 : 0 : continue;
1566 : :
1567 : 0 : s = NULL;
1568 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(ptr)) {
1569 : 0 : s = assoc_array_ptr_to_shortcut(ptr);
1570 : 0 : ptr = s->next_node;
1571 : : }
1572 : :
1573 [ # # ]: 0 : child = assoc_array_ptr_to_node(ptr);
1574 : 0 : new_n->nr_leaves_on_branch += child->nr_leaves_on_branch;
1575 : :
1576 [ # # ]: 0 : if (child->nr_leaves_on_branch <= nr_free + 1) {
1577 : : /* Fold the child node into this one */
1578 : 0 : pr_devel("[%d] fold node %lu/%d [nx %d]\n",
1579 : : slot, child->nr_leaves_on_branch, nr_free + 1,
1580 : : next_slot);
1581 : :
1582 : : /* We would already have reaped an intervening shortcut
1583 : : * on the way back up the tree.
1584 : : */
1585 [ # # ]: 0 : BUG_ON(s);
1586 : :
1587 : 0 : new_n->slots[slot] = NULL;
1588 : 0 : nr_free++;
1589 : 0 : if (slot < next_slot)
1590 : : next_slot = slot;
1591 [ # # ]: 0 : for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) {
1592 : 0 : struct assoc_array_ptr *p = child->slots[i];
1593 [ # # ]: 0 : if (!p)
1594 : 0 : continue;
1595 [ # # ]: 0 : BUG_ON(assoc_array_ptr_is_meta(p));
1596 [ # # ]: 0 : while (new_n->slots[next_slot])
1597 : 0 : next_slot++;
1598 [ # # ]: 0 : BUG_ON(next_slot >= ASSOC_ARRAY_FAN_OUT);
1599 : 0 : new_n->slots[next_slot++] = p;
1600 : 0 : nr_free--;
1601 : : }
1602 : 0 : kfree(child);
1603 : : } else {
1604 : : pr_devel("[%d] retain node %lu/%d [nx %d]\n",
1605 : : slot, child->nr_leaves_on_branch, nr_free + 1,
1606 : : next_slot);
1607 : : }
1608 : : }
1609 : :
1610 : 0 : pr_devel("after: %lu\n", new_n->nr_leaves_on_branch);
1611 : :
1612 : 0 : nr_leaves_on_tree = new_n->nr_leaves_on_branch;
1613 : :
1614 : : /* Excise this node if it is singly occupied by a shortcut */
1615 [ # # ]: 0 : if (nr_free == ASSOC_ARRAY_FAN_OUT - 1) {
1616 [ # # ]: 0 : for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++)
1617 [ # # ]: 0 : if ((ptr = new_n->slots[slot]))
1618 : : break;
1619 : :
1620 [ # # # # ]: 0 : if (assoc_array_ptr_is_meta(ptr) &&
1621 : : assoc_array_ptr_is_shortcut(ptr)) {
1622 : 0 : pr_devel("excise node %p with 1 shortcut\n", new_n);
1623 : 0 : new_s = assoc_array_ptr_to_shortcut(ptr);
1624 : 0 : new_parent = new_n->back_pointer;
1625 : 0 : slot = new_n->parent_slot;
1626 : 0 : kfree(new_n);
1627 [ # # ]: 0 : if (!new_parent) {
1628 : 0 : new_s->back_pointer = NULL;
1629 : 0 : new_s->parent_slot = 0;
1630 : 0 : new_root = ptr;
1631 : 0 : goto gc_complete;
1632 : : }
1633 : :
1634 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(new_parent)) {
1635 : : /* We can discard any preceding shortcut also */
1636 : 0 : struct assoc_array_shortcut *s =
1637 : : assoc_array_ptr_to_shortcut(new_parent);
1638 : :
1639 : 0 : pr_devel("excise preceding shortcut\n");
1640 : :
1641 : 0 : new_parent = new_s->back_pointer = s->back_pointer;
1642 : 0 : slot = new_s->parent_slot = s->parent_slot;
1643 : 0 : kfree(s);
1644 [ # # ]: 0 : if (!new_parent) {
1645 : 0 : new_s->back_pointer = NULL;
1646 : 0 : new_s->parent_slot = 0;
1647 : 0 : new_root = ptr;
1648 : 0 : goto gc_complete;
1649 : : }
1650 : : }
1651 : :
1652 : 0 : new_s->back_pointer = new_parent;
1653 : 0 : new_s->parent_slot = slot;
1654 : 0 : new_n = assoc_array_ptr_to_node(new_parent);
1655 : 0 : new_n->slots[slot] = ptr;
1656 : 0 : goto ascend_old_tree;
1657 : : }
1658 : : }
1659 : :
1660 : : /* Excise any shortcuts we might encounter that point to nodes that
1661 : : * only contain leaves.
1662 : : */
1663 : 0 : ptr = new_n->back_pointer;
1664 [ # # ]: 0 : if (!ptr)
1665 : 0 : goto gc_complete;
1666 : :
1667 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(ptr)) {
1668 [ # # ]: 0 : new_s = assoc_array_ptr_to_shortcut(ptr);
1669 : 0 : new_parent = new_s->back_pointer;
1670 : 0 : slot = new_s->parent_slot;
1671 : :
1672 [ # # ]: 0 : if (new_n->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT) {
1673 : 0 : struct assoc_array_node *n;
1674 : :
1675 : 0 : pr_devel("excise shortcut\n");
1676 : 0 : new_n->back_pointer = new_parent;
1677 : 0 : new_n->parent_slot = slot;
1678 : 0 : kfree(new_s);
1679 [ # # ]: 0 : if (!new_parent) {
1680 : 0 : new_root = assoc_array_node_to_ptr(new_n);
1681 : 0 : goto gc_complete;
1682 : : }
1683 : :
1684 : 0 : n = assoc_array_ptr_to_node(new_parent);
1685 : 0 : n->slots[slot] = assoc_array_node_to_ptr(new_n);
1686 : : }
1687 : : } else {
1688 : : new_parent = ptr;
1689 : : }
1690 : 0 : new_n = assoc_array_ptr_to_node(new_parent);
1691 : :
1692 : 0 : ascend_old_tree:
1693 : 0 : ptr = node->back_pointer;
1694 [ # # ]: 0 : if (assoc_array_ptr_is_shortcut(ptr)) {
1695 [ # # ]: 0 : shortcut = assoc_array_ptr_to_shortcut(ptr);
1696 : 0 : slot = shortcut->parent_slot;
1697 : 0 : cursor = shortcut->back_pointer;
1698 [ # # ]: 0 : if (!cursor)
1699 : 0 : goto gc_complete;
1700 : : } else {
1701 : 0 : slot = node->parent_slot;
1702 : 0 : cursor = ptr;
1703 : : }
1704 [ # # ]: 0 : BUG_ON(!cursor);
1705 : 0 : node = assoc_array_ptr_to_node(cursor);
1706 : 0 : slot++;
1707 : 0 : goto continue_node;
1708 : :
1709 : 0 : gc_complete:
1710 : 0 : edit->set[0].to = new_root;
1711 : 0 : assoc_array_apply_edit(edit);
1712 : 0 : array->nr_leaves_on_tree = nr_leaves_on_tree;
1713 : 0 : return 0;
1714 : :
1715 : 0 : enomem:
1716 : 0 : pr_devel("enomem\n");
1717 : 0 : assoc_array_destroy_subtree(new_root, edit->ops);
1718 : 0 : kfree(edit);
1719 : 0 : return -ENOMEM;
1720 : : }
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