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![Gustavo A. R. Silva](/assets/img/avatar_default.png)
In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. This patch fixes the following warning: lib/assoc_array.c: In function `assoc_array_delete': lib/assoc_array.c:1110:3: warning: this statement may fall through [-Wimplicit-fallthrough=] for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) { ^~~ lib/assoc_array.c:1118:2: note: here case assoc_array_walk_tree_empty: ^~~~ Warning level 3 was used: -Wimplicit-fallthrough=3 This patch is part of the ongoing efforts to enable -Wimplicit-fallthrough. Link: http://lkml.kernel.org/r/20190212212206.GA16378@embeddedor Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1724 lines
52 KiB
C
1724 lines
52 KiB
C
/* 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 (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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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),
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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;
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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;
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unsigned long sc_segments;
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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;
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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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*/
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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;
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consider_node:
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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;
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goto jumped;
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}
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/* There is a shortcut in the slot corresponding to the index key
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* segment. We follow the shortcut if its partial index key matches
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* this leaf's. Otherwise we need to split the shortcut.
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*/
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cursor = ptr;
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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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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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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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* 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
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* 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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{
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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, *parent = NULL;
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int slot = -1;
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pr_devel("-->%s()\n", __func__);
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cursor = root;
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if (!cursor) {
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pr_devel("empty\n");
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return;
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}
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move_to_meta:
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if (assoc_array_ptr_is_shortcut(cursor)) {
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/* Descend through a shortcut */
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pr_devel("[%d] shortcut\n", slot);
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BUG_ON(!assoc_array_ptr_is_shortcut(cursor));
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shortcut = assoc_array_ptr_to_shortcut(cursor);
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BUG_ON(shortcut->back_pointer != parent);
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BUG_ON(slot != -1 && shortcut->parent_slot != slot);
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parent = cursor;
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cursor = shortcut->next_node;
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slot = -1;
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BUG_ON(!assoc_array_ptr_is_node(cursor));
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}
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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);
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BUG_ON(slot != -1 && node->parent_slot != slot);
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slot = 0;
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continue_node:
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pr_devel("Node %p [back=%p]\n", node, node->back_pointer);
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for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
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struct assoc_array_ptr *ptr = node->slots[slot];
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if (!ptr)
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continue;
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if (assoc_array_ptr_is_meta(ptr)) {
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parent = cursor;
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cursor = ptr;
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goto move_to_meta;
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}
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if (ops) {
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pr_devel("[%d] free leaf\n", slot);
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ops->free_object(assoc_array_ptr_to_leaf(ptr));
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}
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}
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parent = node->back_pointer;
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slot = node->parent_slot;
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pr_devel("free node\n");
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kfree(node);
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if (!parent)
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return; /* Done */
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/* Move back up to the parent (may need to free a shortcut on
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* the way up) */
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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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BUG_ON(shortcut->next_node != cursor);
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cursor = parent;
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parent = shortcut->back_pointer;
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slot = shortcut->parent_slot;
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pr_devel("free shortcut\n");
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kfree(shortcut);
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if (!parent)
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return;
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BUG_ON(!assoc_array_ptr_is_node(parent));
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}
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/* Ascend to next slot in parent node */
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pr_devel("ascend to %p[%d]\n", parent, slot);
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cursor = parent;
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node = assoc_array_ptr_to_node(cursor);
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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_destroy - Destroy an associative array
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* @array: The array to destroy.
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* @ops: The operations to use.
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*
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* Discard all metadata and free all objects in an associative array. The
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* array will be empty and ready to use again upon completion. This function
|
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* cannot fail.
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*
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* The caller must prevent all other accesses whilst this takes place as no
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* attempt is made to adjust pointers gracefully to permit RCU readlock-holding
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* accesses to continue. On the other hand, no memory allocation is required.
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*/
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void assoc_array_destroy(struct assoc_array *array,
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const struct assoc_array_ops *ops)
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{
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assoc_array_destroy_subtree(array->root, ops);
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array->root = NULL;
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}
|
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|
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/*
|
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* Handle insertion into an empty tree.
|
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*/
|
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static bool assoc_array_insert_in_empty_tree(struct assoc_array_edit *edit)
|
|
{
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struct assoc_array_node *new_n0;
|
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pr_devel("-->%s()\n", __func__);
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new_n0 = kzalloc(sizeof(struct assoc_array_node), GFP_KERNEL);
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if (!new_n0)
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return false;
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edit->new_meta[0] = assoc_array_node_to_ptr(new_n0);
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edit->leaf_p = &new_n0->slots[0];
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edit->adjust_count_on = new_n0;
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edit->set[0].ptr = &edit->array->root;
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edit->set[0].to = assoc_array_node_to_ptr(new_n0);
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pr_devel("<--%s() = ok [no root]\n", __func__);
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return true;
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}
|
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|
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/*
|
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* Handle insertion into a terminal node.
|
|
*/
|
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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(sizeof(struct assoc_array_shortcut) +
|
|
keylen * sizeof(unsigned long), 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(sizeof(struct assoc_array_shortcut) +
|
|
keylen * sizeof(unsigned long), 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,
|
|
keylen * sizeof(unsigned long));
|
|
|
|
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(sizeof(struct assoc_array_shortcut) +
|
|
keylen * sizeof(unsigned long), 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,
|
|
keylen * sizeof(unsigned long));
|
|
|
|
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;
|
|
}
|
|
/* fall through */
|
|
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;
|
|
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(sizeof(struct assoc_array_shortcut) +
|
|
keylen * sizeof(unsigned long), GFP_KERNEL);
|
|
if (!new_s)
|
|
goto enomem;
|
|
pr_devel("dup shortcut %p -> %p\n", shortcut, new_s);
|
|
memcpy(new_s, shortcut, (sizeof(struct assoc_array_shortcut) +
|
|
keylen * sizeof(unsigned long)));
|
|
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;
|
|
}
|
|
|
|
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 */
|
|
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);
|
|
}
|
|
}
|
|
|
|
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;
|
|
}
|