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1726 lines
52 KiB
1726 lines
52 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* Generic associative array implementation. |
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* |
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* See Documentation/core-api/assoc_array.rst for information. |
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* |
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* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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*/ |
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//#define DEBUG |
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#include <linux/rcupdate.h> |
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#include <linux/slab.h> |
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#include <linux/err.h> |
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#include <linux/assoc_array_priv.h> |
|
|
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/* |
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* Iterate over an associative array. The caller must hold the RCU read lock |
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* or better. |
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*/ |
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static int assoc_array_subtree_iterate(const struct assoc_array_ptr *root, |
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const struct assoc_array_ptr *stop, |
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int (*iterator)(const void *leaf, |
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void *iterator_data), |
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void *iterator_data) |
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{ |
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const struct assoc_array_shortcut *shortcut; |
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const struct assoc_array_node *node; |
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const struct assoc_array_ptr *cursor, *ptr, *parent; |
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unsigned long has_meta; |
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int slot, ret; |
|
|
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cursor = root; |
|
|
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begin_node: |
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if (assoc_array_ptr_is_shortcut(cursor)) { |
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/* Descend through a shortcut */ |
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shortcut = assoc_array_ptr_to_shortcut(cursor); |
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cursor = READ_ONCE(shortcut->next_node); /* Address dependency. */ |
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} |
|
|
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node = assoc_array_ptr_to_node(cursor); |
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slot = 0; |
|
|
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/* We perform two passes of each node. |
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* |
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* The first pass does all the leaves in this node. This means we |
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* don't miss any leaves if the node is split up by insertion whilst |
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* we're iterating over the branches rooted here (we may, however, see |
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* some leaves twice). |
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*/ |
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has_meta = 0; |
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for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
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ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */ |
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has_meta |= (unsigned long)ptr; |
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if (ptr && assoc_array_ptr_is_leaf(ptr)) { |
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/* We need a barrier between the read of the pointer, |
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* which is supplied by the above READ_ONCE(). |
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*/ |
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/* Invoke the callback */ |
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ret = iterator(assoc_array_ptr_to_leaf(ptr), |
|
iterator_data); |
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if (ret) |
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return ret; |
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} |
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} |
|
|
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/* The second pass attends to all the metadata pointers. If we follow |
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* one of these we may find that we don't come back here, but rather go |
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* back to a replacement node with the leaves in a different layout. |
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* |
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* We are guaranteed to make progress, however, as the slot number for |
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* a particular portion of the key space cannot change - and we |
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* continue at the back pointer + 1. |
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*/ |
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if (!(has_meta & ASSOC_ARRAY_PTR_META_TYPE)) |
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goto finished_node; |
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slot = 0; |
|
|
|
continue_node: |
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node = assoc_array_ptr_to_node(cursor); |
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for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
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ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */ |
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if (assoc_array_ptr_is_meta(ptr)) { |
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cursor = ptr; |
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goto begin_node; |
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} |
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} |
|
|
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finished_node: |
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/* Move up to the parent (may need to skip back over a shortcut) */ |
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parent = READ_ONCE(node->back_pointer); /* Address dependency. */ |
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slot = node->parent_slot; |
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if (parent == stop) |
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return 0; |
|
|
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if (assoc_array_ptr_is_shortcut(parent)) { |
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shortcut = assoc_array_ptr_to_shortcut(parent); |
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cursor = parent; |
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parent = READ_ONCE(shortcut->back_pointer); /* Address dependency. */ |
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slot = shortcut->parent_slot; |
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if (parent == stop) |
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return 0; |
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} |
|
|
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/* Ascend to next slot in parent node */ |
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cursor = parent; |
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slot++; |
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goto continue_node; |
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} |
|
|
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/** |
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* assoc_array_iterate - Pass all objects in the array to a callback |
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* @array: The array to iterate over. |
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* @iterator: The callback function. |
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* @iterator_data: Private data for the callback function. |
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* |
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* Iterate over all the objects in an associative array. Each one will be |
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* presented to the iterator function. |
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* |
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* If the array is being modified concurrently with the iteration then it is |
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* possible that some objects in the array will be passed to the iterator |
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* callback more than once - though every object should be passed at least |
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* once. If this is undesirable then the caller must lock against modification |
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* for the duration of this function. |
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* |
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* The function will return 0 if no objects were in the array or else it will |
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* return the result of the last iterator function called. Iteration stops |
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* immediately if any call to the iteration function results in a non-zero |
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* return. |
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* |
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* The caller should hold the RCU read lock or better if concurrent |
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* modification is possible. |
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*/ |
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int assoc_array_iterate(const struct assoc_array *array, |
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int (*iterator)(const void *object, |
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void *iterator_data), |
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void *iterator_data) |
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{ |
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struct assoc_array_ptr *root = READ_ONCE(array->root); /* Address dependency. */ |
|
|
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if (!root) |
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return 0; |
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return assoc_array_subtree_iterate(root, NULL, iterator, iterator_data); |
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} |
|
|
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enum assoc_array_walk_status { |
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assoc_array_walk_tree_empty, |
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assoc_array_walk_found_terminal_node, |
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assoc_array_walk_found_wrong_shortcut, |
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}; |
|
|
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struct assoc_array_walk_result { |
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struct { |
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struct assoc_array_node *node; /* Node in which leaf might be found */ |
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int level; |
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int slot; |
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} terminal_node; |
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struct { |
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struct assoc_array_shortcut *shortcut; |
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int level; |
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int sc_level; |
|
unsigned long sc_segments; |
|
unsigned long dissimilarity; |
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} wrong_shortcut; |
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}; |
|
|
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/* |
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* Navigate through the internal tree looking for the closest node to the key. |
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*/ |
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static enum assoc_array_walk_status |
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assoc_array_walk(const struct assoc_array *array, |
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const struct assoc_array_ops *ops, |
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const void *index_key, |
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struct assoc_array_walk_result *result) |
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{ |
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struct assoc_array_shortcut *shortcut; |
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struct assoc_array_node *node; |
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struct assoc_array_ptr *cursor, *ptr; |
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unsigned long sc_segments, dissimilarity; |
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unsigned long segments; |
|
int level, sc_level, next_sc_level; |
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int slot; |
|
|
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pr_devel("-->%s()\n", __func__); |
|
|
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cursor = READ_ONCE(array->root); /* Address dependency. */ |
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if (!cursor) |
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return assoc_array_walk_tree_empty; |
|
|
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level = 0; |
|
|
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/* Use segments from the key for the new leaf to navigate through the |
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* internal tree, skipping through nodes and shortcuts that are on |
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* route to the destination. Eventually we'll come to a slot that is |
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* either empty or contains a leaf at which point we've found a node in |
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* which the leaf we're looking for might be found or into which it |
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* should be inserted. |
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*/ |
|
jumped: |
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segments = ops->get_key_chunk(index_key, level); |
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pr_devel("segments[%d]: %lx\n", level, segments); |
|
|
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if (assoc_array_ptr_is_shortcut(cursor)) |
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goto follow_shortcut; |
|
|
|
consider_node: |
|
node = assoc_array_ptr_to_node(cursor); |
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slot = segments >> (level & ASSOC_ARRAY_KEY_CHUNK_MASK); |
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slot &= ASSOC_ARRAY_FAN_MASK; |
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ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */ |
|
|
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pr_devel("consider slot %x [ix=%d type=%lu]\n", |
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slot, level, (unsigned long)ptr & 3); |
|
|
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if (!assoc_array_ptr_is_meta(ptr)) { |
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/* The node doesn't have a node/shortcut pointer in the slot |
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* corresponding to the index key that we have to follow. |
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*/ |
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result->terminal_node.node = node; |
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result->terminal_node.level = level; |
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result->terminal_node.slot = slot; |
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pr_devel("<--%s() = terminal_node\n", __func__); |
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return assoc_array_walk_found_terminal_node; |
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} |
|
|
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if (assoc_array_ptr_is_node(ptr)) { |
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/* There is a pointer to a node in the slot corresponding to |
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* this index key segment, so we need to follow it. |
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*/ |
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cursor = ptr; |
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level += ASSOC_ARRAY_LEVEL_STEP; |
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if ((level & ASSOC_ARRAY_KEY_CHUNK_MASK) != 0) |
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goto consider_node; |
|
goto jumped; |
|
} |
|
|
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/* There is a shortcut in the slot corresponding to the index key |
|
* segment. We follow the shortcut if its partial index key matches |
|
* this leaf's. Otherwise we need to split the shortcut. |
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*/ |
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cursor = ptr; |
|
follow_shortcut: |
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shortcut = assoc_array_ptr_to_shortcut(cursor); |
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pr_devel("shortcut to %d\n", shortcut->skip_to_level); |
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sc_level = level + ASSOC_ARRAY_LEVEL_STEP; |
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BUG_ON(sc_level > shortcut->skip_to_level); |
|
|
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do { |
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/* Check the leaf against the shortcut's index key a word at a |
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* time, trimming the final word (the shortcut stores the index |
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* key completely from the root to the shortcut's target). |
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*/ |
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if ((sc_level & ASSOC_ARRAY_KEY_CHUNK_MASK) == 0) |
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segments = ops->get_key_chunk(index_key, sc_level); |
|
|
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sc_segments = shortcut->index_key[sc_level >> ASSOC_ARRAY_KEY_CHUNK_SHIFT]; |
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dissimilarity = segments ^ sc_segments; |
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|
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if (round_up(sc_level, ASSOC_ARRAY_KEY_CHUNK_SIZE) > shortcut->skip_to_level) { |
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/* Trim segments that are beyond the shortcut */ |
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int shift = shortcut->skip_to_level & ASSOC_ARRAY_KEY_CHUNK_MASK; |
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dissimilarity &= ~(ULONG_MAX << shift); |
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next_sc_level = shortcut->skip_to_level; |
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} else { |
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next_sc_level = sc_level + ASSOC_ARRAY_KEY_CHUNK_SIZE; |
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next_sc_level = round_down(next_sc_level, ASSOC_ARRAY_KEY_CHUNK_SIZE); |
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} |
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|
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if (dissimilarity != 0) { |
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/* This shortcut points elsewhere */ |
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result->wrong_shortcut.shortcut = shortcut; |
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result->wrong_shortcut.level = level; |
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result->wrong_shortcut.sc_level = sc_level; |
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result->wrong_shortcut.sc_segments = sc_segments; |
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result->wrong_shortcut.dissimilarity = dissimilarity; |
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return assoc_array_walk_found_wrong_shortcut; |
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} |
|
|
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sc_level = next_sc_level; |
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} while (sc_level < shortcut->skip_to_level); |
|
|
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/* The shortcut matches the leaf's index to this point. */ |
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cursor = READ_ONCE(shortcut->next_node); /* Address dependency. */ |
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if (((level ^ sc_level) & ~ASSOC_ARRAY_KEY_CHUNK_MASK) != 0) { |
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level = sc_level; |
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goto jumped; |
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} else { |
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level = sc_level; |
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goto consider_node; |
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} |
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} |
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|
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/** |
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* assoc_array_find - Find an object by index key |
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* @array: The associative array to search. |
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* @ops: The operations to use. |
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* @index_key: The key to the object. |
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* |
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* Find an object in an associative array by walking through the internal tree |
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* to the node that should contain the object and then searching the leaves |
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* there. NULL is returned if the requested object was not found in the array. |
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* |
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* The caller must hold the RCU read lock or better. |
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*/ |
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void *assoc_array_find(const struct assoc_array *array, |
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const struct assoc_array_ops *ops, |
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const void *index_key) |
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{ |
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struct assoc_array_walk_result result; |
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const struct assoc_array_node *node; |
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const struct assoc_array_ptr *ptr; |
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const void *leaf; |
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int slot; |
|
|
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if (assoc_array_walk(array, ops, index_key, &result) != |
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assoc_array_walk_found_terminal_node) |
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return NULL; |
|
|
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node = result.terminal_node.node; |
|
|
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/* If the target key is available to us, it's has to be pointed to by |
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* the terminal node. |
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*/ |
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for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
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ptr = READ_ONCE(node->slots[slot]); /* Address dependency. */ |
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if (ptr && assoc_array_ptr_is_leaf(ptr)) { |
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/* We need a barrier between the read of the pointer |
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* and dereferencing the pointer - but only if we are |
|
* actually going to dereference it. |
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*/ |
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leaf = assoc_array_ptr_to_leaf(ptr); |
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if (ops->compare_object(leaf, index_key)) |
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return (void *)leaf; |
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} |
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} |
|
|
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return NULL; |
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} |
|
|
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/* |
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* Destructively iterate over an associative array. The caller must prevent |
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* other simultaneous accesses. |
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*/ |
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static void assoc_array_destroy_subtree(struct assoc_array_ptr *root, |
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const struct assoc_array_ops *ops) |
|
{ |
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struct assoc_array_shortcut *shortcut; |
|
struct assoc_array_node *node; |
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struct assoc_array_ptr *cursor, *parent = NULL; |
|
int slot = -1; |
|
|
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pr_devel("-->%s()\n", __func__); |
|
|
|
cursor = root; |
|
if (!cursor) { |
|
pr_devel("empty\n"); |
|
return; |
|
} |
|
|
|
move_to_meta: |
|
if (assoc_array_ptr_is_shortcut(cursor)) { |
|
/* Descend through a shortcut */ |
|
pr_devel("[%d] shortcut\n", slot); |
|
BUG_ON(!assoc_array_ptr_is_shortcut(cursor)); |
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shortcut = assoc_array_ptr_to_shortcut(cursor); |
|
BUG_ON(shortcut->back_pointer != parent); |
|
BUG_ON(slot != -1 && shortcut->parent_slot != slot); |
|
parent = cursor; |
|
cursor = shortcut->next_node; |
|
slot = -1; |
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BUG_ON(!assoc_array_ptr_is_node(cursor)); |
|
} |
|
|
|
pr_devel("[%d] node\n", slot); |
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node = assoc_array_ptr_to_node(cursor); |
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BUG_ON(node->back_pointer != parent); |
|
BUG_ON(slot != -1 && node->parent_slot != slot); |
|
slot = 0; |
|
|
|
continue_node: |
|
pr_devel("Node %p [back=%p]\n", node, node->back_pointer); |
|
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
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struct assoc_array_ptr *ptr = node->slots[slot]; |
|
if (!ptr) |
|
continue; |
|
if (assoc_array_ptr_is_meta(ptr)) { |
|
parent = cursor; |
|
cursor = ptr; |
|
goto move_to_meta; |
|
} |
|
|
|
if (ops) { |
|
pr_devel("[%d] free leaf\n", slot); |
|
ops->free_object(assoc_array_ptr_to_leaf(ptr)); |
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} |
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} |
|
|
|
parent = node->back_pointer; |
|
slot = node->parent_slot; |
|
pr_devel("free node\n"); |
|
kfree(node); |
|
if (!parent) |
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return; /* Done */ |
|
|
|
/* Move back up to the parent (may need to free a shortcut on |
|
* the way up) */ |
|
if (assoc_array_ptr_is_shortcut(parent)) { |
|
shortcut = assoc_array_ptr_to_shortcut(parent); |
|
BUG_ON(shortcut->next_node != cursor); |
|
cursor = parent; |
|
parent = shortcut->back_pointer; |
|
slot = shortcut->parent_slot; |
|
pr_devel("free shortcut\n"); |
|
kfree(shortcut); |
|
if (!parent) |
|
return; |
|
|
|
BUG_ON(!assoc_array_ptr_is_node(parent)); |
|
} |
|
|
|
/* Ascend to next slot in parent node */ |
|
pr_devel("ascend to %p[%d]\n", parent, slot); |
|
cursor = parent; |
|
node = assoc_array_ptr_to_node(cursor); |
|
slot++; |
|
goto continue_node; |
|
} |
|
|
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/** |
|
* assoc_array_destroy - Destroy an associative array |
|
* @array: The array to destroy. |
|
* @ops: The operations to use. |
|
* |
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* Discard all metadata and free all objects in an associative array. The |
|
* array will be empty and ready to use again upon completion. This function |
|
* cannot fail. |
|
* |
|
* The caller must prevent all other accesses whilst this takes place as no |
|
* attempt is made to adjust pointers gracefully to permit RCU readlock-holding |
|
* accesses to continue. On the other hand, no memory allocation is required. |
|
*/ |
|
void assoc_array_destroy(struct assoc_array *array, |
|
const struct assoc_array_ops *ops) |
|
{ |
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assoc_array_destroy_subtree(array->root, ops); |
|
array->root = NULL; |
|
} |
|
|
|
/* |
|
* Handle insertion into an empty tree. |
|
*/ |
|
static bool assoc_array_insert_in_empty_tree(struct assoc_array_edit *edit) |
|
{ |
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struct assoc_array_node *new_n0; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n0) |
|
return false; |
|
|
|
edit->new_meta[0] = assoc_array_node_to_ptr(new_n0); |
|
edit->leaf_p = &new_n0->slots[0]; |
|
edit->adjust_count_on = new_n0; |
|
edit->set[0].ptr = &edit->array->root; |
|
edit->set[0].to = assoc_array_node_to_ptr(new_n0); |
|
|
|
pr_devel("<--%s() = ok [no root]\n", __func__); |
|
return true; |
|
} |
|
|
|
/* |
|
* Handle insertion into a terminal node. |
|
*/ |
|
static bool assoc_array_insert_into_terminal_node(struct assoc_array_edit *edit, |
|
const struct assoc_array_ops *ops, |
|
const void *index_key, |
|
struct assoc_array_walk_result *result) |
|
{ |
|
struct assoc_array_shortcut *shortcut, *new_s0; |
|
struct assoc_array_node *node, *new_n0, *new_n1, *side; |
|
struct assoc_array_ptr *ptr; |
|
unsigned long dissimilarity, base_seg, blank; |
|
size_t keylen; |
|
bool have_meta; |
|
int level, diff; |
|
int slot, next_slot, free_slot, i, j; |
|
|
|
node = result->terminal_node.node; |
|
level = result->terminal_node.level; |
|
edit->segment_cache[ASSOC_ARRAY_FAN_OUT] = result->terminal_node.slot; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
/* We arrived at a node which doesn't have an onward node or shortcut |
|
* pointer that we have to follow. This means that (a) the leaf we |
|
* want must go here (either by insertion or replacement) or (b) we |
|
* need to split this node and insert in one of the fragments. |
|
*/ |
|
free_slot = -1; |
|
|
|
/* Firstly, we have to check the leaves in this node to see if there's |
|
* a matching one we should replace in place. |
|
*/ |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
ptr = node->slots[i]; |
|
if (!ptr) { |
|
free_slot = i; |
|
continue; |
|
} |
|
if (assoc_array_ptr_is_leaf(ptr) && |
|
ops->compare_object(assoc_array_ptr_to_leaf(ptr), |
|
index_key)) { |
|
pr_devel("replace in slot %d\n", i); |
|
edit->leaf_p = &node->slots[i]; |
|
edit->dead_leaf = node->slots[i]; |
|
pr_devel("<--%s() = ok [replace]\n", __func__); |
|
return true; |
|
} |
|
} |
|
|
|
/* If there is a free slot in this node then we can just insert the |
|
* leaf here. |
|
*/ |
|
if (free_slot >= 0) { |
|
pr_devel("insert in free slot %d\n", free_slot); |
|
edit->leaf_p = &node->slots[free_slot]; |
|
edit->adjust_count_on = node; |
|
pr_devel("<--%s() = ok [insert]\n", __func__); |
|
return true; |
|
} |
|
|
|
/* The node has no spare slots - so we're either going to have to split |
|
* it or insert another node before it. |
|
* |
|
* Whatever, we're going to need at least two new nodes - so allocate |
|
* those now. We may also need a new shortcut, but we deal with that |
|
* when we need it. |
|
*/ |
|
new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n0) |
|
return false; |
|
edit->new_meta[0] = assoc_array_node_to_ptr(new_n0); |
|
new_n1 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n1) |
|
return false; |
|
edit->new_meta[1] = assoc_array_node_to_ptr(new_n1); |
|
|
|
/* We need to find out how similar the leaves are. */ |
|
pr_devel("no spare slots\n"); |
|
have_meta = false; |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
ptr = node->slots[i]; |
|
if (assoc_array_ptr_is_meta(ptr)) { |
|
edit->segment_cache[i] = 0xff; |
|
have_meta = true; |
|
continue; |
|
} |
|
base_seg = ops->get_object_key_chunk( |
|
assoc_array_ptr_to_leaf(ptr), level); |
|
base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK; |
|
edit->segment_cache[i] = base_seg & ASSOC_ARRAY_FAN_MASK; |
|
} |
|
|
|
if (have_meta) { |
|
pr_devel("have meta\n"); |
|
goto split_node; |
|
} |
|
|
|
/* The node contains only leaves */ |
|
dissimilarity = 0; |
|
base_seg = edit->segment_cache[0]; |
|
for (i = 1; i < ASSOC_ARRAY_FAN_OUT; i++) |
|
dissimilarity |= edit->segment_cache[i] ^ base_seg; |
|
|
|
pr_devel("only leaves; dissimilarity=%lx\n", dissimilarity); |
|
|
|
if ((dissimilarity & ASSOC_ARRAY_FAN_MASK) == 0) { |
|
/* The old leaves all cluster in the same slot. We will need |
|
* to insert a shortcut if the new node wants to cluster with them. |
|
*/ |
|
if ((edit->segment_cache[ASSOC_ARRAY_FAN_OUT] ^ base_seg) == 0) |
|
goto all_leaves_cluster_together; |
|
|
|
/* Otherwise all the old leaves cluster in the same slot, but |
|
* the new leaf wants to go into a different slot - so we |
|
* create a new node (n0) to hold the new leaf and a pointer to |
|
* a new node (n1) holding all the old leaves. |
|
* |
|
* This can be done by falling through to the node splitting |
|
* path. |
|
*/ |
|
pr_devel("present leaves cluster but not new leaf\n"); |
|
} |
|
|
|
split_node: |
|
pr_devel("split node\n"); |
|
|
|
/* We need to split the current node. The node must contain anything |
|
* from a single leaf (in the one leaf case, this leaf will cluster |
|
* with the new leaf) and the rest meta-pointers, to all leaves, some |
|
* of which may cluster. |
|
* |
|
* It won't contain the case in which all the current leaves plus the |
|
* new leaves want to cluster in the same slot. |
|
* |
|
* We need to expel at least two leaves out of a set consisting of the |
|
* leaves in the node and the new leaf. The current meta pointers can |
|
* just be copied as they shouldn't cluster with any of the leaves. |
|
* |
|
* We need a new node (n0) to replace the current one and a new node to |
|
* take the expelled nodes (n1). |
|
*/ |
|
edit->set[0].to = assoc_array_node_to_ptr(new_n0); |
|
new_n0->back_pointer = node->back_pointer; |
|
new_n0->parent_slot = node->parent_slot; |
|
new_n1->back_pointer = assoc_array_node_to_ptr(new_n0); |
|
new_n1->parent_slot = -1; /* Need to calculate this */ |
|
|
|
do_split_node: |
|
pr_devel("do_split_node\n"); |
|
|
|
new_n0->nr_leaves_on_branch = node->nr_leaves_on_branch; |
|
new_n1->nr_leaves_on_branch = 0; |
|
|
|
/* Begin by finding two matching leaves. There have to be at least two |
|
* that match - even if there are meta pointers - because any leaf that |
|
* would match a slot with a meta pointer in it must be somewhere |
|
* behind that meta pointer and cannot be here. Further, given N |
|
* remaining leaf slots, we now have N+1 leaves to go in them. |
|
*/ |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
slot = edit->segment_cache[i]; |
|
if (slot != 0xff) |
|
for (j = i + 1; j < ASSOC_ARRAY_FAN_OUT + 1; j++) |
|
if (edit->segment_cache[j] == slot) |
|
goto found_slot_for_multiple_occupancy; |
|
} |
|
found_slot_for_multiple_occupancy: |
|
pr_devel("same slot: %x %x [%02x]\n", i, j, slot); |
|
BUG_ON(i >= ASSOC_ARRAY_FAN_OUT); |
|
BUG_ON(j >= ASSOC_ARRAY_FAN_OUT + 1); |
|
BUG_ON(slot >= ASSOC_ARRAY_FAN_OUT); |
|
|
|
new_n1->parent_slot = slot; |
|
|
|
/* Metadata pointers cannot change slot */ |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) |
|
if (assoc_array_ptr_is_meta(node->slots[i])) |
|
new_n0->slots[i] = node->slots[i]; |
|
else |
|
new_n0->slots[i] = NULL; |
|
BUG_ON(new_n0->slots[slot] != NULL); |
|
new_n0->slots[slot] = assoc_array_node_to_ptr(new_n1); |
|
|
|
/* Filter the leaf pointers between the new nodes */ |
|
free_slot = -1; |
|
next_slot = 0; |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
if (assoc_array_ptr_is_meta(node->slots[i])) |
|
continue; |
|
if (edit->segment_cache[i] == slot) { |
|
new_n1->slots[next_slot++] = node->slots[i]; |
|
new_n1->nr_leaves_on_branch++; |
|
} else { |
|
do { |
|
free_slot++; |
|
} while (new_n0->slots[free_slot] != NULL); |
|
new_n0->slots[free_slot] = node->slots[i]; |
|
} |
|
} |
|
|
|
pr_devel("filtered: f=%x n=%x\n", free_slot, next_slot); |
|
|
|
if (edit->segment_cache[ASSOC_ARRAY_FAN_OUT] != slot) { |
|
do { |
|
free_slot++; |
|
} while (new_n0->slots[free_slot] != NULL); |
|
edit->leaf_p = &new_n0->slots[free_slot]; |
|
edit->adjust_count_on = new_n0; |
|
} else { |
|
edit->leaf_p = &new_n1->slots[next_slot++]; |
|
edit->adjust_count_on = new_n1; |
|
} |
|
|
|
BUG_ON(next_slot <= 1); |
|
|
|
edit->set_backpointers_to = assoc_array_node_to_ptr(new_n0); |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
if (edit->segment_cache[i] == 0xff) { |
|
ptr = node->slots[i]; |
|
BUG_ON(assoc_array_ptr_is_leaf(ptr)); |
|
if (assoc_array_ptr_is_node(ptr)) { |
|
side = assoc_array_ptr_to_node(ptr); |
|
edit->set_backpointers[i] = &side->back_pointer; |
|
} else { |
|
shortcut = assoc_array_ptr_to_shortcut(ptr); |
|
edit->set_backpointers[i] = &shortcut->back_pointer; |
|
} |
|
} |
|
} |
|
|
|
ptr = node->back_pointer; |
|
if (!ptr) |
|
edit->set[0].ptr = &edit->array->root; |
|
else if (assoc_array_ptr_is_node(ptr)) |
|
edit->set[0].ptr = &assoc_array_ptr_to_node(ptr)->slots[node->parent_slot]; |
|
else |
|
edit->set[0].ptr = &assoc_array_ptr_to_shortcut(ptr)->next_node; |
|
edit->excised_meta[0] = assoc_array_node_to_ptr(node); |
|
pr_devel("<--%s() = ok [split node]\n", __func__); |
|
return true; |
|
|
|
all_leaves_cluster_together: |
|
/* All the leaves, new and old, want to cluster together in this node |
|
* in the same slot, so we have to replace this node with a shortcut to |
|
* skip over the identical parts of the key and then place a pair of |
|
* nodes, one inside the other, at the end of the shortcut and |
|
* distribute the keys between them. |
|
* |
|
* Firstly we need to work out where the leaves start diverging as a |
|
* bit position into their keys so that we know how big the shortcut |
|
* needs to be. |
|
* |
|
* We only need to make a single pass of N of the N+1 leaves because if |
|
* any keys differ between themselves at bit X then at least one of |
|
* them must also differ with the base key at bit X or before. |
|
*/ |
|
pr_devel("all leaves cluster together\n"); |
|
diff = INT_MAX; |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
int x = ops->diff_objects(assoc_array_ptr_to_leaf(node->slots[i]), |
|
index_key); |
|
if (x < diff) { |
|
BUG_ON(x < 0); |
|
diff = x; |
|
} |
|
} |
|
BUG_ON(diff == INT_MAX); |
|
BUG_ON(diff < level + ASSOC_ARRAY_LEVEL_STEP); |
|
|
|
keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE); |
|
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT; |
|
|
|
new_s0 = kzalloc(struct_size(new_s0, index_key, keylen), GFP_KERNEL); |
|
if (!new_s0) |
|
return false; |
|
edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s0); |
|
|
|
edit->set[0].to = assoc_array_shortcut_to_ptr(new_s0); |
|
new_s0->back_pointer = node->back_pointer; |
|
new_s0->parent_slot = node->parent_slot; |
|
new_s0->next_node = assoc_array_node_to_ptr(new_n0); |
|
new_n0->back_pointer = assoc_array_shortcut_to_ptr(new_s0); |
|
new_n0->parent_slot = 0; |
|
new_n1->back_pointer = assoc_array_node_to_ptr(new_n0); |
|
new_n1->parent_slot = -1; /* Need to calculate this */ |
|
|
|
new_s0->skip_to_level = level = diff & ~ASSOC_ARRAY_LEVEL_STEP_MASK; |
|
pr_devel("skip_to_level = %d [diff %d]\n", level, diff); |
|
BUG_ON(level <= 0); |
|
|
|
for (i = 0; i < keylen; i++) |
|
new_s0->index_key[i] = |
|
ops->get_key_chunk(index_key, i * ASSOC_ARRAY_KEY_CHUNK_SIZE); |
|
|
|
if (level & ASSOC_ARRAY_KEY_CHUNK_MASK) { |
|
blank = ULONG_MAX << (level & ASSOC_ARRAY_KEY_CHUNK_MASK); |
|
pr_devel("blank off [%zu] %d: %lx\n", keylen - 1, level, blank); |
|
new_s0->index_key[keylen - 1] &= ~blank; |
|
} |
|
|
|
/* This now reduces to a node splitting exercise for which we'll need |
|
* to regenerate the disparity table. |
|
*/ |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
ptr = node->slots[i]; |
|
base_seg = ops->get_object_key_chunk(assoc_array_ptr_to_leaf(ptr), |
|
level); |
|
base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK; |
|
edit->segment_cache[i] = base_seg & ASSOC_ARRAY_FAN_MASK; |
|
} |
|
|
|
base_seg = ops->get_key_chunk(index_key, level); |
|
base_seg >>= level & ASSOC_ARRAY_KEY_CHUNK_MASK; |
|
edit->segment_cache[ASSOC_ARRAY_FAN_OUT] = base_seg & ASSOC_ARRAY_FAN_MASK; |
|
goto do_split_node; |
|
} |
|
|
|
/* |
|
* Handle insertion into the middle of a shortcut. |
|
*/ |
|
static bool assoc_array_insert_mid_shortcut(struct assoc_array_edit *edit, |
|
const struct assoc_array_ops *ops, |
|
struct assoc_array_walk_result *result) |
|
{ |
|
struct assoc_array_shortcut *shortcut, *new_s0, *new_s1; |
|
struct assoc_array_node *node, *new_n0, *side; |
|
unsigned long sc_segments, dissimilarity, blank; |
|
size_t keylen; |
|
int level, sc_level, diff; |
|
int sc_slot; |
|
|
|
shortcut = result->wrong_shortcut.shortcut; |
|
level = result->wrong_shortcut.level; |
|
sc_level = result->wrong_shortcut.sc_level; |
|
sc_segments = result->wrong_shortcut.sc_segments; |
|
dissimilarity = result->wrong_shortcut.dissimilarity; |
|
|
|
pr_devel("-->%s(ix=%d dis=%lx scix=%d)\n", |
|
__func__, level, dissimilarity, sc_level); |
|
|
|
/* We need to split a shortcut and insert a node between the two |
|
* pieces. Zero-length pieces will be dispensed with entirely. |
|
* |
|
* First of all, we need to find out in which level the first |
|
* difference was. |
|
*/ |
|
diff = __ffs(dissimilarity); |
|
diff &= ~ASSOC_ARRAY_LEVEL_STEP_MASK; |
|
diff += sc_level & ~ASSOC_ARRAY_KEY_CHUNK_MASK; |
|
pr_devel("diff=%d\n", diff); |
|
|
|
if (!shortcut->back_pointer) { |
|
edit->set[0].ptr = &edit->array->root; |
|
} else if (assoc_array_ptr_is_node(shortcut->back_pointer)) { |
|
node = assoc_array_ptr_to_node(shortcut->back_pointer); |
|
edit->set[0].ptr = &node->slots[shortcut->parent_slot]; |
|
} else { |
|
BUG(); |
|
} |
|
|
|
edit->excised_meta[0] = assoc_array_shortcut_to_ptr(shortcut); |
|
|
|
/* Create a new node now since we're going to need it anyway */ |
|
new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n0) |
|
return false; |
|
edit->new_meta[0] = assoc_array_node_to_ptr(new_n0); |
|
edit->adjust_count_on = new_n0; |
|
|
|
/* Insert a new shortcut before the new node if this segment isn't of |
|
* zero length - otherwise we just connect the new node directly to the |
|
* parent. |
|
*/ |
|
level += ASSOC_ARRAY_LEVEL_STEP; |
|
if (diff > level) { |
|
pr_devel("pre-shortcut %d...%d\n", level, diff); |
|
keylen = round_up(diff, ASSOC_ARRAY_KEY_CHUNK_SIZE); |
|
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT; |
|
|
|
new_s0 = kzalloc(struct_size(new_s0, index_key, keylen), |
|
GFP_KERNEL); |
|
if (!new_s0) |
|
return false; |
|
edit->new_meta[1] = assoc_array_shortcut_to_ptr(new_s0); |
|
edit->set[0].to = assoc_array_shortcut_to_ptr(new_s0); |
|
new_s0->back_pointer = shortcut->back_pointer; |
|
new_s0->parent_slot = shortcut->parent_slot; |
|
new_s0->next_node = assoc_array_node_to_ptr(new_n0); |
|
new_s0->skip_to_level = diff; |
|
|
|
new_n0->back_pointer = assoc_array_shortcut_to_ptr(new_s0); |
|
new_n0->parent_slot = 0; |
|
|
|
memcpy(new_s0->index_key, shortcut->index_key, |
|
flex_array_size(new_s0, index_key, keylen)); |
|
|
|
blank = ULONG_MAX << (diff & ASSOC_ARRAY_KEY_CHUNK_MASK); |
|
pr_devel("blank off [%zu] %d: %lx\n", keylen - 1, diff, blank); |
|
new_s0->index_key[keylen - 1] &= ~blank; |
|
} else { |
|
pr_devel("no pre-shortcut\n"); |
|
edit->set[0].to = assoc_array_node_to_ptr(new_n0); |
|
new_n0->back_pointer = shortcut->back_pointer; |
|
new_n0->parent_slot = shortcut->parent_slot; |
|
} |
|
|
|
side = assoc_array_ptr_to_node(shortcut->next_node); |
|
new_n0->nr_leaves_on_branch = side->nr_leaves_on_branch; |
|
|
|
/* We need to know which slot in the new node is going to take a |
|
* metadata pointer. |
|
*/ |
|
sc_slot = sc_segments >> (diff & ASSOC_ARRAY_KEY_CHUNK_MASK); |
|
sc_slot &= ASSOC_ARRAY_FAN_MASK; |
|
|
|
pr_devel("new slot %lx >> %d -> %d\n", |
|
sc_segments, diff & ASSOC_ARRAY_KEY_CHUNK_MASK, sc_slot); |
|
|
|
/* Determine whether we need to follow the new node with a replacement |
|
* for the current shortcut. We could in theory reuse the current |
|
* shortcut if its parent slot number doesn't change - but that's a |
|
* 1-in-16 chance so not worth expending the code upon. |
|
*/ |
|
level = diff + ASSOC_ARRAY_LEVEL_STEP; |
|
if (level < shortcut->skip_to_level) { |
|
pr_devel("post-shortcut %d...%d\n", level, shortcut->skip_to_level); |
|
keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE); |
|
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT; |
|
|
|
new_s1 = kzalloc(struct_size(new_s1, index_key, keylen), |
|
GFP_KERNEL); |
|
if (!new_s1) |
|
return false; |
|
edit->new_meta[2] = assoc_array_shortcut_to_ptr(new_s1); |
|
|
|
new_s1->back_pointer = assoc_array_node_to_ptr(new_n0); |
|
new_s1->parent_slot = sc_slot; |
|
new_s1->next_node = shortcut->next_node; |
|
new_s1->skip_to_level = shortcut->skip_to_level; |
|
|
|
new_n0->slots[sc_slot] = assoc_array_shortcut_to_ptr(new_s1); |
|
|
|
memcpy(new_s1->index_key, shortcut->index_key, |
|
flex_array_size(new_s1, index_key, keylen)); |
|
|
|
edit->set[1].ptr = &side->back_pointer; |
|
edit->set[1].to = assoc_array_shortcut_to_ptr(new_s1); |
|
} else { |
|
pr_devel("no post-shortcut\n"); |
|
|
|
/* We don't have to replace the pointed-to node as long as we |
|
* use memory barriers to make sure the parent slot number is |
|
* changed before the back pointer (the parent slot number is |
|
* irrelevant to the old parent shortcut). |
|
*/ |
|
new_n0->slots[sc_slot] = shortcut->next_node; |
|
edit->set_parent_slot[0].p = &side->parent_slot; |
|
edit->set_parent_slot[0].to = sc_slot; |
|
edit->set[1].ptr = &side->back_pointer; |
|
edit->set[1].to = assoc_array_node_to_ptr(new_n0); |
|
} |
|
|
|
/* Install the new leaf in a spare slot in the new node. */ |
|
if (sc_slot == 0) |
|
edit->leaf_p = &new_n0->slots[1]; |
|
else |
|
edit->leaf_p = &new_n0->slots[0]; |
|
|
|
pr_devel("<--%s() = ok [split shortcut]\n", __func__); |
|
return edit; |
|
} |
|
|
|
/** |
|
* assoc_array_insert - Script insertion of an object into an associative array |
|
* @array: The array to insert into. |
|
* @ops: The operations to use. |
|
* @index_key: The key to insert at. |
|
* @object: The object to insert. |
|
* |
|
* Precalculate and preallocate a script for the insertion or replacement of an |
|
* object in an associative array. This results in an edit script that can |
|
* either be applied or cancelled. |
|
* |
|
* The function returns a pointer to an edit script or -ENOMEM. |
|
* |
|
* The caller should lock against other modifications and must continue to hold |
|
* the lock until assoc_array_apply_edit() has been called. |
|
* |
|
* Accesses to the tree may take place concurrently with this function, |
|
* provided they hold the RCU read lock. |
|
*/ |
|
struct assoc_array_edit *assoc_array_insert(struct assoc_array *array, |
|
const struct assoc_array_ops *ops, |
|
const void *index_key, |
|
void *object) |
|
{ |
|
struct assoc_array_walk_result result; |
|
struct assoc_array_edit *edit; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
/* The leaf pointer we're given must not have the bottom bit set as we |
|
* use those for type-marking the pointer. NULL pointers are also not |
|
* allowed as they indicate an empty slot but we have to allow them |
|
* here as they can be updated later. |
|
*/ |
|
BUG_ON(assoc_array_ptr_is_meta(object)); |
|
|
|
edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL); |
|
if (!edit) |
|
return ERR_PTR(-ENOMEM); |
|
edit->array = array; |
|
edit->ops = ops; |
|
edit->leaf = assoc_array_leaf_to_ptr(object); |
|
edit->adjust_count_by = 1; |
|
|
|
switch (assoc_array_walk(array, ops, index_key, &result)) { |
|
case assoc_array_walk_tree_empty: |
|
/* Allocate a root node if there isn't one yet */ |
|
if (!assoc_array_insert_in_empty_tree(edit)) |
|
goto enomem; |
|
return edit; |
|
|
|
case assoc_array_walk_found_terminal_node: |
|
/* We found a node that doesn't have a node/shortcut pointer in |
|
* the slot corresponding to the index key that we have to |
|
* follow. |
|
*/ |
|
if (!assoc_array_insert_into_terminal_node(edit, ops, index_key, |
|
&result)) |
|
goto enomem; |
|
return edit; |
|
|
|
case assoc_array_walk_found_wrong_shortcut: |
|
/* We found a shortcut that didn't match our key in a slot we |
|
* needed to follow. |
|
*/ |
|
if (!assoc_array_insert_mid_shortcut(edit, ops, &result)) |
|
goto enomem; |
|
return edit; |
|
} |
|
|
|
enomem: |
|
/* Clean up after an out of memory error */ |
|
pr_devel("enomem\n"); |
|
assoc_array_cancel_edit(edit); |
|
return ERR_PTR(-ENOMEM); |
|
} |
|
|
|
/** |
|
* assoc_array_insert_set_object - Set the new object pointer in an edit script |
|
* @edit: The edit script to modify. |
|
* @object: The object pointer to set. |
|
* |
|
* Change the object to be inserted in an edit script. The object pointed to |
|
* by the old object is not freed. This must be done prior to applying the |
|
* script. |
|
*/ |
|
void assoc_array_insert_set_object(struct assoc_array_edit *edit, void *object) |
|
{ |
|
BUG_ON(!object); |
|
edit->leaf = assoc_array_leaf_to_ptr(object); |
|
} |
|
|
|
struct assoc_array_delete_collapse_context { |
|
struct assoc_array_node *node; |
|
const void *skip_leaf; |
|
int slot; |
|
}; |
|
|
|
/* |
|
* Subtree collapse to node iterator. |
|
*/ |
|
static int assoc_array_delete_collapse_iterator(const void *leaf, |
|
void *iterator_data) |
|
{ |
|
struct assoc_array_delete_collapse_context *collapse = iterator_data; |
|
|
|
if (leaf == collapse->skip_leaf) |
|
return 0; |
|
|
|
BUG_ON(collapse->slot >= ASSOC_ARRAY_FAN_OUT); |
|
|
|
collapse->node->slots[collapse->slot++] = assoc_array_leaf_to_ptr(leaf); |
|
return 0; |
|
} |
|
|
|
/** |
|
* assoc_array_delete - Script deletion of an object from an associative array |
|
* @array: The array to search. |
|
* @ops: The operations to use. |
|
* @index_key: The key to the object. |
|
* |
|
* Precalculate and preallocate a script for the deletion of an object from an |
|
* associative array. This results in an edit script that can either be |
|
* applied or cancelled. |
|
* |
|
* The function returns a pointer to an edit script if the object was found, |
|
* NULL if the object was not found or -ENOMEM. |
|
* |
|
* The caller should lock against other modifications and must continue to hold |
|
* the lock until assoc_array_apply_edit() has been called. |
|
* |
|
* Accesses to the tree may take place concurrently with this function, |
|
* provided they hold the RCU read lock. |
|
*/ |
|
struct assoc_array_edit *assoc_array_delete(struct assoc_array *array, |
|
const struct assoc_array_ops *ops, |
|
const void *index_key) |
|
{ |
|
struct assoc_array_delete_collapse_context collapse; |
|
struct assoc_array_walk_result result; |
|
struct assoc_array_node *node, *new_n0; |
|
struct assoc_array_edit *edit; |
|
struct assoc_array_ptr *ptr; |
|
bool has_meta; |
|
int slot, i; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL); |
|
if (!edit) |
|
return ERR_PTR(-ENOMEM); |
|
edit->array = array; |
|
edit->ops = ops; |
|
edit->adjust_count_by = -1; |
|
|
|
switch (assoc_array_walk(array, ops, index_key, &result)) { |
|
case assoc_array_walk_found_terminal_node: |
|
/* We found a node that should contain the leaf we've been |
|
* asked to remove - *if* it's in the tree. |
|
*/ |
|
pr_devel("terminal_node\n"); |
|
node = result.terminal_node.node; |
|
|
|
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
|
ptr = node->slots[slot]; |
|
if (ptr && |
|
assoc_array_ptr_is_leaf(ptr) && |
|
ops->compare_object(assoc_array_ptr_to_leaf(ptr), |
|
index_key)) |
|
goto found_leaf; |
|
} |
|
fallthrough; |
|
case assoc_array_walk_tree_empty: |
|
case assoc_array_walk_found_wrong_shortcut: |
|
default: |
|
assoc_array_cancel_edit(edit); |
|
pr_devel("not found\n"); |
|
return NULL; |
|
} |
|
|
|
found_leaf: |
|
BUG_ON(array->nr_leaves_on_tree <= 0); |
|
|
|
/* In the simplest form of deletion we just clear the slot and release |
|
* the leaf after a suitable interval. |
|
*/ |
|
edit->dead_leaf = node->slots[slot]; |
|
edit->set[0].ptr = &node->slots[slot]; |
|
edit->set[0].to = NULL; |
|
edit->adjust_count_on = node; |
|
|
|
/* If that concludes erasure of the last leaf, then delete the entire |
|
* internal array. |
|
*/ |
|
if (array->nr_leaves_on_tree == 1) { |
|
edit->set[1].ptr = &array->root; |
|
edit->set[1].to = NULL; |
|
edit->adjust_count_on = NULL; |
|
edit->excised_subtree = array->root; |
|
pr_devel("all gone\n"); |
|
return edit; |
|
} |
|
|
|
/* However, we'd also like to clear up some metadata blocks if we |
|
* possibly can. |
|
* |
|
* We go for a simple algorithm of: if this node has FAN_OUT or fewer |
|
* leaves in it, then attempt to collapse it - and attempt to |
|
* recursively collapse up the tree. |
|
* |
|
* We could also try and collapse in partially filled subtrees to take |
|
* up space in this node. |
|
*/ |
|
if (node->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT + 1) { |
|
struct assoc_array_node *parent, *grandparent; |
|
struct assoc_array_ptr *ptr; |
|
|
|
/* First of all, we need to know if this node has metadata so |
|
* that we don't try collapsing if all the leaves are already |
|
* here. |
|
*/ |
|
has_meta = false; |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
ptr = node->slots[i]; |
|
if (assoc_array_ptr_is_meta(ptr)) { |
|
has_meta = true; |
|
break; |
|
} |
|
} |
|
|
|
pr_devel("leaves: %ld [m=%d]\n", |
|
node->nr_leaves_on_branch - 1, has_meta); |
|
|
|
/* Look further up the tree to see if we can collapse this node |
|
* into a more proximal node too. |
|
*/ |
|
parent = node; |
|
collapse_up: |
|
pr_devel("collapse subtree: %ld\n", parent->nr_leaves_on_branch); |
|
|
|
ptr = parent->back_pointer; |
|
if (!ptr) |
|
goto do_collapse; |
|
if (assoc_array_ptr_is_shortcut(ptr)) { |
|
struct assoc_array_shortcut *s = assoc_array_ptr_to_shortcut(ptr); |
|
ptr = s->back_pointer; |
|
if (!ptr) |
|
goto do_collapse; |
|
} |
|
|
|
grandparent = assoc_array_ptr_to_node(ptr); |
|
if (grandparent->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT + 1) { |
|
parent = grandparent; |
|
goto collapse_up; |
|
} |
|
|
|
do_collapse: |
|
/* There's no point collapsing if the original node has no meta |
|
* pointers to discard and if we didn't merge into one of that |
|
* node's ancestry. |
|
*/ |
|
if (has_meta || parent != node) { |
|
node = parent; |
|
|
|
/* Create a new node to collapse into */ |
|
new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n0) |
|
goto enomem; |
|
edit->new_meta[0] = assoc_array_node_to_ptr(new_n0); |
|
|
|
new_n0->back_pointer = node->back_pointer; |
|
new_n0->parent_slot = node->parent_slot; |
|
new_n0->nr_leaves_on_branch = node->nr_leaves_on_branch; |
|
edit->adjust_count_on = new_n0; |
|
|
|
collapse.node = new_n0; |
|
collapse.skip_leaf = assoc_array_ptr_to_leaf(edit->dead_leaf); |
|
collapse.slot = 0; |
|
assoc_array_subtree_iterate(assoc_array_node_to_ptr(node), |
|
node->back_pointer, |
|
assoc_array_delete_collapse_iterator, |
|
&collapse); |
|
pr_devel("collapsed %d,%lu\n", collapse.slot, new_n0->nr_leaves_on_branch); |
|
BUG_ON(collapse.slot != new_n0->nr_leaves_on_branch - 1); |
|
|
|
if (!node->back_pointer) { |
|
edit->set[1].ptr = &array->root; |
|
} else if (assoc_array_ptr_is_leaf(node->back_pointer)) { |
|
BUG(); |
|
} else if (assoc_array_ptr_is_node(node->back_pointer)) { |
|
struct assoc_array_node *p = |
|
assoc_array_ptr_to_node(node->back_pointer); |
|
edit->set[1].ptr = &p->slots[node->parent_slot]; |
|
} else if (assoc_array_ptr_is_shortcut(node->back_pointer)) { |
|
struct assoc_array_shortcut *s = |
|
assoc_array_ptr_to_shortcut(node->back_pointer); |
|
edit->set[1].ptr = &s->next_node; |
|
} |
|
edit->set[1].to = assoc_array_node_to_ptr(new_n0); |
|
edit->excised_subtree = assoc_array_node_to_ptr(node); |
|
} |
|
} |
|
|
|
return edit; |
|
|
|
enomem: |
|
/* Clean up after an out of memory error */ |
|
pr_devel("enomem\n"); |
|
assoc_array_cancel_edit(edit); |
|
return ERR_PTR(-ENOMEM); |
|
} |
|
|
|
/** |
|
* assoc_array_clear - Script deletion of all objects from an associative array |
|
* @array: The array to clear. |
|
* @ops: The operations to use. |
|
* |
|
* Precalculate and preallocate a script for the deletion of all the objects |
|
* from an associative array. This results in an edit script that can either |
|
* be applied or cancelled. |
|
* |
|
* The function returns a pointer to an edit script if there are objects to be |
|
* deleted, NULL if there are no objects in the array or -ENOMEM. |
|
* |
|
* The caller should lock against other modifications and must continue to hold |
|
* the lock until assoc_array_apply_edit() has been called. |
|
* |
|
* Accesses to the tree may take place concurrently with this function, |
|
* provided they hold the RCU read lock. |
|
*/ |
|
struct assoc_array_edit *assoc_array_clear(struct assoc_array *array, |
|
const struct assoc_array_ops *ops) |
|
{ |
|
struct assoc_array_edit *edit; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
if (!array->root) |
|
return NULL; |
|
|
|
edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL); |
|
if (!edit) |
|
return ERR_PTR(-ENOMEM); |
|
edit->array = array; |
|
edit->ops = ops; |
|
edit->set[1].ptr = &array->root; |
|
edit->set[1].to = NULL; |
|
edit->excised_subtree = array->root; |
|
edit->ops_for_excised_subtree = ops; |
|
pr_devel("all gone\n"); |
|
return edit; |
|
} |
|
|
|
/* |
|
* Handle the deferred destruction after an applied edit. |
|
*/ |
|
static void assoc_array_rcu_cleanup(struct rcu_head *head) |
|
{ |
|
struct assoc_array_edit *edit = |
|
container_of(head, struct assoc_array_edit, rcu); |
|
int i; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
if (edit->dead_leaf) |
|
edit->ops->free_object(assoc_array_ptr_to_leaf(edit->dead_leaf)); |
|
for (i = 0; i < ARRAY_SIZE(edit->excised_meta); i++) |
|
if (edit->excised_meta[i]) |
|
kfree(assoc_array_ptr_to_node(edit->excised_meta[i])); |
|
|
|
if (edit->excised_subtree) { |
|
BUG_ON(assoc_array_ptr_is_leaf(edit->excised_subtree)); |
|
if (assoc_array_ptr_is_node(edit->excised_subtree)) { |
|
struct assoc_array_node *n = |
|
assoc_array_ptr_to_node(edit->excised_subtree); |
|
n->back_pointer = NULL; |
|
} else { |
|
struct assoc_array_shortcut *s = |
|
assoc_array_ptr_to_shortcut(edit->excised_subtree); |
|
s->back_pointer = NULL; |
|
} |
|
assoc_array_destroy_subtree(edit->excised_subtree, |
|
edit->ops_for_excised_subtree); |
|
} |
|
|
|
kfree(edit); |
|
} |
|
|
|
/** |
|
* assoc_array_apply_edit - Apply an edit script to an associative array |
|
* @edit: The script to apply. |
|
* |
|
* Apply an edit script to an associative array to effect an insertion, |
|
* deletion or clearance. As the edit script includes preallocated memory, |
|
* this is guaranteed not to fail. |
|
* |
|
* The edit script, dead objects and dead metadata will be scheduled for |
|
* destruction after an RCU grace period to permit those doing read-only |
|
* accesses on the array to continue to do so under the RCU read lock whilst |
|
* the edit is taking place. |
|
*/ |
|
void assoc_array_apply_edit(struct assoc_array_edit *edit) |
|
{ |
|
struct assoc_array_shortcut *shortcut; |
|
struct assoc_array_node *node; |
|
struct assoc_array_ptr *ptr; |
|
int i; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
smp_wmb(); |
|
if (edit->leaf_p) |
|
*edit->leaf_p = edit->leaf; |
|
|
|
smp_wmb(); |
|
for (i = 0; i < ARRAY_SIZE(edit->set_parent_slot); i++) |
|
if (edit->set_parent_slot[i].p) |
|
*edit->set_parent_slot[i].p = edit->set_parent_slot[i].to; |
|
|
|
smp_wmb(); |
|
for (i = 0; i < ARRAY_SIZE(edit->set_backpointers); i++) |
|
if (edit->set_backpointers[i]) |
|
*edit->set_backpointers[i] = edit->set_backpointers_to; |
|
|
|
smp_wmb(); |
|
for (i = 0; i < ARRAY_SIZE(edit->set); i++) |
|
if (edit->set[i].ptr) |
|
*edit->set[i].ptr = edit->set[i].to; |
|
|
|
if (edit->array->root == NULL) { |
|
edit->array->nr_leaves_on_tree = 0; |
|
} else if (edit->adjust_count_on) { |
|
node = edit->adjust_count_on; |
|
for (;;) { |
|
node->nr_leaves_on_branch += edit->adjust_count_by; |
|
|
|
ptr = node->back_pointer; |
|
if (!ptr) |
|
break; |
|
if (assoc_array_ptr_is_shortcut(ptr)) { |
|
shortcut = assoc_array_ptr_to_shortcut(ptr); |
|
ptr = shortcut->back_pointer; |
|
if (!ptr) |
|
break; |
|
} |
|
BUG_ON(!assoc_array_ptr_is_node(ptr)); |
|
node = assoc_array_ptr_to_node(ptr); |
|
} |
|
|
|
edit->array->nr_leaves_on_tree += edit->adjust_count_by; |
|
} |
|
|
|
call_rcu(&edit->rcu, assoc_array_rcu_cleanup); |
|
} |
|
|
|
/** |
|
* assoc_array_cancel_edit - Discard an edit script. |
|
* @edit: The script to discard. |
|
* |
|
* Free an edit script and all the preallocated data it holds without making |
|
* any changes to the associative array it was intended for. |
|
* |
|
* NOTE! In the case of an insertion script, this does _not_ release the leaf |
|
* that was to be inserted. That is left to the caller. |
|
*/ |
|
void assoc_array_cancel_edit(struct assoc_array_edit *edit) |
|
{ |
|
struct assoc_array_ptr *ptr; |
|
int i; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
/* Clean up after an out of memory error */ |
|
for (i = 0; i < ARRAY_SIZE(edit->new_meta); i++) { |
|
ptr = edit->new_meta[i]; |
|
if (ptr) { |
|
if (assoc_array_ptr_is_node(ptr)) |
|
kfree(assoc_array_ptr_to_node(ptr)); |
|
else |
|
kfree(assoc_array_ptr_to_shortcut(ptr)); |
|
} |
|
} |
|
kfree(edit); |
|
} |
|
|
|
/** |
|
* assoc_array_gc - Garbage collect an associative array. |
|
* @array: The array to clean. |
|
* @ops: The operations to use. |
|
* @iterator: A callback function to pass judgement on each object. |
|
* @iterator_data: Private data for the callback function. |
|
* |
|
* Collect garbage from an associative array and pack down the internal tree to |
|
* save memory. |
|
* |
|
* The iterator function is asked to pass judgement upon each object in the |
|
* array. If it returns false, the object is discard and if it returns true, |
|
* the object is kept. If it returns true, it must increment the object's |
|
* usage count (or whatever it needs to do to retain it) before returning. |
|
* |
|
* This function returns 0 if successful or -ENOMEM if out of memory. In the |
|
* latter case, the array is not changed. |
|
* |
|
* The caller should lock against other modifications and must continue to hold |
|
* the lock until assoc_array_apply_edit() has been called. |
|
* |
|
* Accesses to the tree may take place concurrently with this function, |
|
* provided they hold the RCU read lock. |
|
*/ |
|
int assoc_array_gc(struct assoc_array *array, |
|
const struct assoc_array_ops *ops, |
|
bool (*iterator)(void *object, void *iterator_data), |
|
void *iterator_data) |
|
{ |
|
struct assoc_array_shortcut *shortcut, *new_s; |
|
struct assoc_array_node *node, *new_n; |
|
struct assoc_array_edit *edit; |
|
struct assoc_array_ptr *cursor, *ptr; |
|
struct assoc_array_ptr *new_root, *new_parent, **new_ptr_pp; |
|
unsigned long nr_leaves_on_tree; |
|
bool retained; |
|
int keylen, slot, nr_free, next_slot, i; |
|
|
|
pr_devel("-->%s()\n", __func__); |
|
|
|
if (!array->root) |
|
return 0; |
|
|
|
edit = kzalloc(sizeof(struct assoc_array_edit), GFP_KERNEL); |
|
if (!edit) |
|
return -ENOMEM; |
|
edit->array = array; |
|
edit->ops = ops; |
|
edit->ops_for_excised_subtree = ops; |
|
edit->set[0].ptr = &array->root; |
|
edit->excised_subtree = array->root; |
|
|
|
new_root = new_parent = NULL; |
|
new_ptr_pp = &new_root; |
|
cursor = array->root; |
|
|
|
descend: |
|
/* If this point is a shortcut, then we need to duplicate it and |
|
* advance the target cursor. |
|
*/ |
|
if (assoc_array_ptr_is_shortcut(cursor)) { |
|
shortcut = assoc_array_ptr_to_shortcut(cursor); |
|
keylen = round_up(shortcut->skip_to_level, ASSOC_ARRAY_KEY_CHUNK_SIZE); |
|
keylen >>= ASSOC_ARRAY_KEY_CHUNK_SHIFT; |
|
new_s = kmalloc(struct_size(new_s, index_key, keylen), |
|
GFP_KERNEL); |
|
if (!new_s) |
|
goto enomem; |
|
pr_devel("dup shortcut %p -> %p\n", shortcut, new_s); |
|
memcpy(new_s, shortcut, struct_size(new_s, index_key, keylen)); |
|
new_s->back_pointer = new_parent; |
|
new_s->parent_slot = shortcut->parent_slot; |
|
*new_ptr_pp = new_parent = assoc_array_shortcut_to_ptr(new_s); |
|
new_ptr_pp = &new_s->next_node; |
|
cursor = shortcut->next_node; |
|
} |
|
|
|
/* Duplicate the node at this position */ |
|
node = assoc_array_ptr_to_node(cursor); |
|
new_n = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL); |
|
if (!new_n) |
|
goto enomem; |
|
pr_devel("dup node %p -> %p\n", node, new_n); |
|
new_n->back_pointer = new_parent; |
|
new_n->parent_slot = node->parent_slot; |
|
*new_ptr_pp = new_parent = assoc_array_node_to_ptr(new_n); |
|
new_ptr_pp = NULL; |
|
slot = 0; |
|
|
|
continue_node: |
|
/* Filter across any leaves and gc any subtrees */ |
|
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
|
ptr = node->slots[slot]; |
|
if (!ptr) |
|
continue; |
|
|
|
if (assoc_array_ptr_is_leaf(ptr)) { |
|
if (iterator(assoc_array_ptr_to_leaf(ptr), |
|
iterator_data)) |
|
/* The iterator will have done any reference |
|
* counting on the object for us. |
|
*/ |
|
new_n->slots[slot] = ptr; |
|
continue; |
|
} |
|
|
|
new_ptr_pp = &new_n->slots[slot]; |
|
cursor = ptr; |
|
goto descend; |
|
} |
|
|
|
retry_compress: |
|
pr_devel("-- compress node %p --\n", new_n); |
|
|
|
/* Count up the number of empty slots in this node and work out the |
|
* subtree leaf count. |
|
*/ |
|
new_n->nr_leaves_on_branch = 0; |
|
nr_free = 0; |
|
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
|
ptr = new_n->slots[slot]; |
|
if (!ptr) |
|
nr_free++; |
|
else if (assoc_array_ptr_is_leaf(ptr)) |
|
new_n->nr_leaves_on_branch++; |
|
} |
|
pr_devel("free=%d, leaves=%lu\n", nr_free, new_n->nr_leaves_on_branch); |
|
|
|
/* See what we can fold in */ |
|
retained = false; |
|
next_slot = 0; |
|
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) { |
|
struct assoc_array_shortcut *s; |
|
struct assoc_array_node *child; |
|
|
|
ptr = new_n->slots[slot]; |
|
if (!ptr || assoc_array_ptr_is_leaf(ptr)) |
|
continue; |
|
|
|
s = NULL; |
|
if (assoc_array_ptr_is_shortcut(ptr)) { |
|
s = assoc_array_ptr_to_shortcut(ptr); |
|
ptr = s->next_node; |
|
} |
|
|
|
child = assoc_array_ptr_to_node(ptr); |
|
new_n->nr_leaves_on_branch += child->nr_leaves_on_branch; |
|
|
|
if (child->nr_leaves_on_branch <= nr_free + 1) { |
|
/* Fold the child node into this one */ |
|
pr_devel("[%d] fold node %lu/%d [nx %d]\n", |
|
slot, child->nr_leaves_on_branch, nr_free + 1, |
|
next_slot); |
|
|
|
/* We would already have reaped an intervening shortcut |
|
* on the way back up the tree. |
|
*/ |
|
BUG_ON(s); |
|
|
|
new_n->slots[slot] = NULL; |
|
nr_free++; |
|
if (slot < next_slot) |
|
next_slot = slot; |
|
for (i = 0; i < ASSOC_ARRAY_FAN_OUT; i++) { |
|
struct assoc_array_ptr *p = child->slots[i]; |
|
if (!p) |
|
continue; |
|
BUG_ON(assoc_array_ptr_is_meta(p)); |
|
while (new_n->slots[next_slot]) |
|
next_slot++; |
|
BUG_ON(next_slot >= ASSOC_ARRAY_FAN_OUT); |
|
new_n->slots[next_slot++] = p; |
|
nr_free--; |
|
} |
|
kfree(child); |
|
} else { |
|
pr_devel("[%d] retain node %lu/%d [nx %d]\n", |
|
slot, child->nr_leaves_on_branch, nr_free + 1, |
|
next_slot); |
|
retained = true; |
|
} |
|
} |
|
|
|
if (retained && new_n->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT) { |
|
pr_devel("internal nodes remain despite enough space, retrying\n"); |
|
goto retry_compress; |
|
} |
|
pr_devel("after: %lu\n", new_n->nr_leaves_on_branch); |
|
|
|
nr_leaves_on_tree = new_n->nr_leaves_on_branch; |
|
|
|
/* Excise this node if it is singly occupied by a shortcut */ |
|
if (nr_free == ASSOC_ARRAY_FAN_OUT - 1) { |
|
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) |
|
if ((ptr = new_n->slots[slot])) |
|
break; |
|
|
|
if (assoc_array_ptr_is_meta(ptr) && |
|
assoc_array_ptr_is_shortcut(ptr)) { |
|
pr_devel("excise node %p with 1 shortcut\n", new_n); |
|
new_s = assoc_array_ptr_to_shortcut(ptr); |
|
new_parent = new_n->back_pointer; |
|
slot = new_n->parent_slot; |
|
kfree(new_n); |
|
if (!new_parent) { |
|
new_s->back_pointer = NULL; |
|
new_s->parent_slot = 0; |
|
new_root = ptr; |
|
goto gc_complete; |
|
} |
|
|
|
if (assoc_array_ptr_is_shortcut(new_parent)) { |
|
/* We can discard any preceding shortcut also */ |
|
struct assoc_array_shortcut *s = |
|
assoc_array_ptr_to_shortcut(new_parent); |
|
|
|
pr_devel("excise preceding shortcut\n"); |
|
|
|
new_parent = new_s->back_pointer = s->back_pointer; |
|
slot = new_s->parent_slot = s->parent_slot; |
|
kfree(s); |
|
if (!new_parent) { |
|
new_s->back_pointer = NULL; |
|
new_s->parent_slot = 0; |
|
new_root = ptr; |
|
goto gc_complete; |
|
} |
|
} |
|
|
|
new_s->back_pointer = new_parent; |
|
new_s->parent_slot = slot; |
|
new_n = assoc_array_ptr_to_node(new_parent); |
|
new_n->slots[slot] = ptr; |
|
goto ascend_old_tree; |
|
} |
|
} |
|
|
|
/* Excise any shortcuts we might encounter that point to nodes that |
|
* only contain leaves. |
|
*/ |
|
ptr = new_n->back_pointer; |
|
if (!ptr) |
|
goto gc_complete; |
|
|
|
if (assoc_array_ptr_is_shortcut(ptr)) { |
|
new_s = assoc_array_ptr_to_shortcut(ptr); |
|
new_parent = new_s->back_pointer; |
|
slot = new_s->parent_slot; |
|
|
|
if (new_n->nr_leaves_on_branch <= ASSOC_ARRAY_FAN_OUT) { |
|
struct assoc_array_node *n; |
|
|
|
pr_devel("excise shortcut\n"); |
|
new_n->back_pointer = new_parent; |
|
new_n->parent_slot = slot; |
|
kfree(new_s); |
|
if (!new_parent) { |
|
new_root = assoc_array_node_to_ptr(new_n); |
|
goto gc_complete; |
|
} |
|
|
|
n = assoc_array_ptr_to_node(new_parent); |
|
n->slots[slot] = assoc_array_node_to_ptr(new_n); |
|
} |
|
} else { |
|
new_parent = ptr; |
|
} |
|
new_n = assoc_array_ptr_to_node(new_parent); |
|
|
|
ascend_old_tree: |
|
ptr = node->back_pointer; |
|
if (assoc_array_ptr_is_shortcut(ptr)) { |
|
shortcut = assoc_array_ptr_to_shortcut(ptr); |
|
slot = shortcut->parent_slot; |
|
cursor = shortcut->back_pointer; |
|
if (!cursor) |
|
goto gc_complete; |
|
} else { |
|
slot = node->parent_slot; |
|
cursor = ptr; |
|
} |
|
BUG_ON(!cursor); |
|
node = assoc_array_ptr_to_node(cursor); |
|
slot++; |
|
goto continue_node; |
|
|
|
gc_complete: |
|
edit->set[0].to = new_root; |
|
assoc_array_apply_edit(edit); |
|
array->nr_leaves_on_tree = nr_leaves_on_tree; |
|
return 0; |
|
|
|
enomem: |
|
pr_devel("enomem\n"); |
|
assoc_array_destroy_subtree(new_root, edit->ops); |
|
kfree(edit); |
|
return -ENOMEM; |
|
}
|
|
|