![David Chinner](/assets/img/avatar_default.png)
XFS filestreams functionality uses radix trees and the preload functions. XFS can be built as a module and hence we need radix_tree_preload() exported. radix_tree_preload_end() is a static inline, so it doesn't need exporting. Signed-Off-By: Dave Chinner <dgc@sgi.com> Signed-Off-By: Tim Shimmin <tes@sgi.com>
1028 lines
25 KiB
C
1028 lines
25 KiB
C
/*
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* Copyright (C) 2001 Momchil Velikov
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* Portions Copyright (C) 2001 Christoph Hellwig
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* Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
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* Copyright (C) 2006 Nick Piggin
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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 License as
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* published by the Free Software Foundation; either version 2, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/radix-tree.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/gfp.h>
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#include <linux/string.h>
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#include <linux/bitops.h>
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#include <linux/rcupdate.h>
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#ifdef __KERNEL__
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#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
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#else
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#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
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#endif
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#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
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#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
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#define RADIX_TREE_TAG_LONGS \
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((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
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struct radix_tree_node {
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unsigned int height; /* Height from the bottom */
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unsigned int count;
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struct rcu_head rcu_head;
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void *slots[RADIX_TREE_MAP_SIZE];
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unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
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};
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struct radix_tree_path {
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struct radix_tree_node *node;
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int offset;
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};
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#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
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#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
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static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
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/*
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* Radix tree node cache.
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*/
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static struct kmem_cache *radix_tree_node_cachep;
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/*
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* Per-cpu pool of preloaded nodes
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*/
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struct radix_tree_preload {
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int nr;
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struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
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};
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DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
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static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
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{
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return root->gfp_mask & __GFP_BITS_MASK;
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}
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/*
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* This assumes that the caller has performed appropriate preallocation, and
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* that the caller has pinned this thread of control to the current CPU.
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*/
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static struct radix_tree_node *
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radix_tree_node_alloc(struct radix_tree_root *root)
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{
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struct radix_tree_node *ret;
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gfp_t gfp_mask = root_gfp_mask(root);
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ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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if (ret == NULL && !(gfp_mask & __GFP_WAIT)) {
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struct radix_tree_preload *rtp;
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rtp = &__get_cpu_var(radix_tree_preloads);
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if (rtp->nr) {
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ret = rtp->nodes[rtp->nr - 1];
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rtp->nodes[rtp->nr - 1] = NULL;
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rtp->nr--;
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}
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}
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BUG_ON(radix_tree_is_direct_ptr(ret));
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return ret;
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}
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static void radix_tree_node_rcu_free(struct rcu_head *head)
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{
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struct radix_tree_node *node =
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container_of(head, struct radix_tree_node, rcu_head);
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kmem_cache_free(radix_tree_node_cachep, node);
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}
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static inline void
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radix_tree_node_free(struct radix_tree_node *node)
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{
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call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
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}
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/*
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* Load up this CPU's radix_tree_node buffer with sufficient objects to
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* ensure that the addition of a single element in the tree cannot fail. On
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* success, return zero, with preemption disabled. On error, return -ENOMEM
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* with preemption not disabled.
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*/
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int radix_tree_preload(gfp_t gfp_mask)
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{
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struct radix_tree_preload *rtp;
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struct radix_tree_node *node;
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int ret = -ENOMEM;
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preempt_disable();
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rtp = &__get_cpu_var(radix_tree_preloads);
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while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
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preempt_enable();
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node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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if (node == NULL)
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goto out;
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preempt_disable();
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rtp = &__get_cpu_var(radix_tree_preloads);
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if (rtp->nr < ARRAY_SIZE(rtp->nodes))
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rtp->nodes[rtp->nr++] = node;
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else
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kmem_cache_free(radix_tree_node_cachep, node);
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}
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ret = 0;
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out:
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return ret;
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}
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EXPORT_SYMBOL(radix_tree_preload);
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static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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__set_bit(offset, node->tags[tag]);
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}
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static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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__clear_bit(offset, node->tags[tag]);
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}
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static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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return test_bit(offset, node->tags[tag]);
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}
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static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
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{
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root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
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{
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root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear_all(struct radix_tree_root *root)
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{
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root->gfp_mask &= __GFP_BITS_MASK;
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}
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static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
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{
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return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
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}
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/*
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* Returns 1 if any slot in the node has this tag set.
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* Otherwise returns 0.
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*/
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static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
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{
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int idx;
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for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
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if (node->tags[tag][idx])
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return 1;
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}
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return 0;
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}
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/*
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* Return the maximum key which can be store into a
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* radix tree with height HEIGHT.
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*/
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static inline unsigned long radix_tree_maxindex(unsigned int height)
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{
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return height_to_maxindex[height];
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}
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/*
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* Extend a radix tree so it can store key @index.
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*/
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static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
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{
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struct radix_tree_node *node;
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unsigned int height;
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int tag;
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/* Figure out what the height should be. */
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height = root->height + 1;
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while (index > radix_tree_maxindex(height))
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height++;
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if (root->rnode == NULL) {
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root->height = height;
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goto out;
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}
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do {
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unsigned int newheight;
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if (!(node = radix_tree_node_alloc(root)))
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return -ENOMEM;
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/* Increase the height. */
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node->slots[0] = radix_tree_direct_to_ptr(root->rnode);
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/* Propagate the aggregated tag info into the new root */
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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if (root_tag_get(root, tag))
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tag_set(node, tag, 0);
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}
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newheight = root->height+1;
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node->height = newheight;
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node->count = 1;
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rcu_assign_pointer(root->rnode, node);
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root->height = newheight;
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} while (height > root->height);
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out:
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return 0;
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}
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/**
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* radix_tree_insert - insert into a radix tree
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* @root: radix tree root
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* @index: index key
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* @item: item to insert
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*
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* Insert an item into the radix tree at position @index.
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*/
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int radix_tree_insert(struct radix_tree_root *root,
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unsigned long index, void *item)
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{
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struct radix_tree_node *node = NULL, *slot;
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unsigned int height, shift;
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int offset;
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int error;
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BUG_ON(radix_tree_is_direct_ptr(item));
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/* Make sure the tree is high enough. */
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if (index > radix_tree_maxindex(root->height)) {
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error = radix_tree_extend(root, index);
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if (error)
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return error;
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}
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slot = root->rnode;
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height = root->height;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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offset = 0; /* uninitialised var warning */
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while (height > 0) {
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if (slot == NULL) {
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/* Have to add a child node. */
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if (!(slot = radix_tree_node_alloc(root)))
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return -ENOMEM;
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slot->height = height;
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if (node) {
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rcu_assign_pointer(node->slots[offset], slot);
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node->count++;
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} else
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rcu_assign_pointer(root->rnode, slot);
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}
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/* Go a level down */
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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node = slot;
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slot = node->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
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if (slot != NULL)
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return -EEXIST;
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if (node) {
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node->count++;
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rcu_assign_pointer(node->slots[offset], item);
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BUG_ON(tag_get(node, 0, offset));
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BUG_ON(tag_get(node, 1, offset));
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} else {
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rcu_assign_pointer(root->rnode, radix_tree_ptr_to_direct(item));
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BUG_ON(root_tag_get(root, 0));
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BUG_ON(root_tag_get(root, 1));
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}
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return 0;
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}
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EXPORT_SYMBOL(radix_tree_insert);
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/**
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* radix_tree_lookup_slot - lookup a slot in a radix tree
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* @root: radix tree root
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* @index: index key
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*
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* Returns: the slot corresponding to the position @index in the
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* radix tree @root. This is useful for update-if-exists operations.
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*
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* This function cannot be called under rcu_read_lock, it must be
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* excluded from writers, as must the returned slot for subsequent
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* use by radix_tree_deref_slot() and radix_tree_replace slot.
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* Caller must hold tree write locked across slot lookup and
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* replace.
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*/
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void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
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{
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unsigned int height, shift;
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struct radix_tree_node *node, **slot;
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node = root->rnode;
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if (node == NULL)
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return NULL;
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if (radix_tree_is_direct_ptr(node)) {
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if (index > 0)
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return NULL;
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return (void **)&root->rnode;
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}
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height = node->height;
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if (index > radix_tree_maxindex(height))
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return NULL;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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do {
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slot = (struct radix_tree_node **)
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(node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
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node = *slot;
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if (node == NULL)
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return NULL;
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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} while (height > 0);
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return (void **)slot;
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}
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EXPORT_SYMBOL(radix_tree_lookup_slot);
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/**
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* radix_tree_lookup - perform lookup operation on a radix tree
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* @root: radix tree root
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* @index: index key
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*
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* Lookup the item at the position @index in the radix tree @root.
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*
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* This function can be called under rcu_read_lock, however the caller
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* must manage lifetimes of leaf nodes (eg. RCU may also be used to free
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* them safely). No RCU barriers are required to access or modify the
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* returned item, however.
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*/
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void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
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{
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unsigned int height, shift;
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struct radix_tree_node *node, **slot;
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node = rcu_dereference(root->rnode);
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if (node == NULL)
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return NULL;
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if (radix_tree_is_direct_ptr(node)) {
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if (index > 0)
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return NULL;
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return radix_tree_direct_to_ptr(node);
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}
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height = node->height;
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if (index > radix_tree_maxindex(height))
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return NULL;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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do {
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slot = (struct radix_tree_node **)
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(node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
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node = rcu_dereference(*slot);
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if (node == NULL)
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return NULL;
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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} while (height > 0);
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return node;
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}
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EXPORT_SYMBOL(radix_tree_lookup);
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/**
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* radix_tree_tag_set - set a tag on a radix tree node
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* @root: radix tree root
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* @index: index key
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* @tag: tag index
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*
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* Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
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* corresponding to @index in the radix tree. From
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* the root all the way down to the leaf node.
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*
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* Returns the address of the tagged item. Setting a tag on a not-present
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* item is a bug.
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*/
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void *radix_tree_tag_set(struct radix_tree_root *root,
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unsigned long index, unsigned int tag)
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{
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unsigned int height, shift;
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struct radix_tree_node *slot;
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|
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height = root->height;
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BUG_ON(index > radix_tree_maxindex(height));
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|
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slot = root->rnode;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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|
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while (height > 0) {
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int offset;
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|
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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if (!tag_get(slot, tag, offset))
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tag_set(slot, tag, offset);
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slot = slot->slots[offset];
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BUG_ON(slot == NULL);
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shift -= RADIX_TREE_MAP_SHIFT;
|
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height--;
|
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}
|
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|
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/* set the root's tag bit */
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if (slot && !root_tag_get(root, tag))
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root_tag_set(root, tag);
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|
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_tag_set);
|
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|
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/**
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* radix_tree_tag_clear - clear a tag on a radix tree node
|
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* @root: radix tree root
|
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* @index: index key
|
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* @tag: tag index
|
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*
|
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* Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
|
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* corresponding to @index in the radix tree. If
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* this causes the leaf node to have no tags set then clear the tag in the
|
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* next-to-leaf node, etc.
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*
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* Returns the address of the tagged item on success, else NULL. ie:
|
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* has the same return value and semantics as radix_tree_lookup().
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*/
|
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void *radix_tree_tag_clear(struct radix_tree_root *root,
|
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unsigned long index, unsigned int tag)
|
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{
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struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
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struct radix_tree_node *slot = NULL;
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unsigned int height, shift;
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height = root->height;
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if (index > radix_tree_maxindex(height))
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goto out;
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|
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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pathp->node = NULL;
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slot = root->rnode;
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|
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while (height > 0) {
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int offset;
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|
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if (slot == NULL)
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goto out;
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offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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pathp[1].offset = offset;
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pathp[1].node = slot;
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slot = slot->slots[offset];
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pathp++;
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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}
|
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|
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if (slot == NULL)
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goto out;
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|
|
while (pathp->node) {
|
|
if (!tag_get(pathp->node, tag, pathp->offset))
|
|
goto out;
|
|
tag_clear(pathp->node, tag, pathp->offset);
|
|
if (any_tag_set(pathp->node, tag))
|
|
goto out;
|
|
pathp--;
|
|
}
|
|
|
|
/* clear the root's tag bit */
|
|
if (root_tag_get(root, tag))
|
|
root_tag_clear(root, tag);
|
|
|
|
out:
|
|
return slot;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_clear);
|
|
|
|
#ifndef __KERNEL__ /* Only the test harness uses this at present */
|
|
/**
|
|
* radix_tree_tag_get - get a tag on a radix tree node
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @tag: tag index (< RADIX_TREE_MAX_TAGS)
|
|
*
|
|
* Return values:
|
|
*
|
|
* 0: tag not present or not set
|
|
* 1: tag set
|
|
*/
|
|
int radix_tree_tag_get(struct radix_tree_root *root,
|
|
unsigned long index, unsigned int tag)
|
|
{
|
|
unsigned int height, shift;
|
|
struct radix_tree_node *node;
|
|
int saw_unset_tag = 0;
|
|
|
|
/* check the root's tag bit */
|
|
if (!root_tag_get(root, tag))
|
|
return 0;
|
|
|
|
node = rcu_dereference(root->rnode);
|
|
if (node == NULL)
|
|
return 0;
|
|
|
|
if (radix_tree_is_direct_ptr(node))
|
|
return (index == 0);
|
|
|
|
height = node->height;
|
|
if (index > radix_tree_maxindex(height))
|
|
return 0;
|
|
|
|
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
|
|
|
for ( ; ; ) {
|
|
int offset;
|
|
|
|
if (node == NULL)
|
|
return 0;
|
|
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
|
|
/*
|
|
* This is just a debug check. Later, we can bale as soon as
|
|
* we see an unset tag.
|
|
*/
|
|
if (!tag_get(node, tag, offset))
|
|
saw_unset_tag = 1;
|
|
if (height == 1) {
|
|
int ret = tag_get(node, tag, offset);
|
|
|
|
BUG_ON(ret && saw_unset_tag);
|
|
return !!ret;
|
|
}
|
|
node = rcu_dereference(node->slots[offset]);
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
height--;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_get);
|
|
#endif
|
|
|
|
static unsigned int
|
|
__lookup(struct radix_tree_node *slot, void **results, unsigned long index,
|
|
unsigned int max_items, unsigned long *next_index)
|
|
{
|
|
unsigned int nr_found = 0;
|
|
unsigned int shift, height;
|
|
unsigned long i;
|
|
|
|
height = slot->height;
|
|
if (height == 0)
|
|
goto out;
|
|
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
|
|
|
|
for ( ; height > 1; height--) {
|
|
i = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
for (;;) {
|
|
if (slot->slots[i] != NULL)
|
|
break;
|
|
index &= ~((1UL << shift) - 1);
|
|
index += 1UL << shift;
|
|
if (index == 0)
|
|
goto out; /* 32-bit wraparound */
|
|
i++;
|
|
if (i == RADIX_TREE_MAP_SIZE)
|
|
goto out;
|
|
}
|
|
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
slot = rcu_dereference(slot->slots[i]);
|
|
if (slot == NULL)
|
|
goto out;
|
|
}
|
|
|
|
/* Bottom level: grab some items */
|
|
for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
|
|
struct radix_tree_node *node;
|
|
index++;
|
|
node = slot->slots[i];
|
|
if (node) {
|
|
results[nr_found++] = rcu_dereference(node);
|
|
if (nr_found == max_items)
|
|
goto out;
|
|
}
|
|
}
|
|
out:
|
|
*next_index = index;
|
|
return nr_found;
|
|
}
|
|
|
|
/**
|
|
* radix_tree_gang_lookup - perform multiple lookup on a radix tree
|
|
* @root: radix tree root
|
|
* @results: where the results of the lookup are placed
|
|
* @first_index: start the lookup from this key
|
|
* @max_items: place up to this many items at *results
|
|
*
|
|
* Performs an index-ascending scan of the tree for present items. Places
|
|
* them at *@results and returns the number of items which were placed at
|
|
* *@results.
|
|
*
|
|
* The implementation is naive.
|
|
*
|
|
* Like radix_tree_lookup, radix_tree_gang_lookup may be called under
|
|
* rcu_read_lock. In this case, rather than the returned results being
|
|
* an atomic snapshot of the tree at a single point in time, the semantics
|
|
* of an RCU protected gang lookup are as though multiple radix_tree_lookups
|
|
* have been issued in individual locks, and results stored in 'results'.
|
|
*/
|
|
unsigned int
|
|
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
|
|
unsigned long first_index, unsigned int max_items)
|
|
{
|
|
unsigned long max_index;
|
|
struct radix_tree_node *node;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
node = rcu_dereference(root->rnode);
|
|
if (!node)
|
|
return 0;
|
|
|
|
if (radix_tree_is_direct_ptr(node)) {
|
|
if (first_index > 0)
|
|
return 0;
|
|
node = radix_tree_direct_to_ptr(node);
|
|
results[0] = rcu_dereference(node);
|
|
return 1;
|
|
}
|
|
|
|
max_index = radix_tree_maxindex(node->height);
|
|
|
|
ret = 0;
|
|
while (ret < max_items) {
|
|
unsigned int nr_found;
|
|
unsigned long next_index; /* Index of next search */
|
|
|
|
if (cur_index > max_index)
|
|
break;
|
|
nr_found = __lookup(node, results + ret, cur_index,
|
|
max_items - ret, &next_index);
|
|
ret += nr_found;
|
|
if (next_index == 0)
|
|
break;
|
|
cur_index = next_index;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_gang_lookup);
|
|
|
|
/*
|
|
* FIXME: the two tag_get()s here should use find_next_bit() instead of
|
|
* open-coding the search.
|
|
*/
|
|
static unsigned int
|
|
__lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index,
|
|
unsigned int max_items, unsigned long *next_index, unsigned int tag)
|
|
{
|
|
unsigned int nr_found = 0;
|
|
unsigned int shift, height;
|
|
|
|
height = slot->height;
|
|
if (height == 0)
|
|
goto out;
|
|
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
|
|
|
|
while (height > 0) {
|
|
unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
|
|
|
|
for (;;) {
|
|
if (tag_get(slot, tag, i))
|
|
break;
|
|
index &= ~((1UL << shift) - 1);
|
|
index += 1UL << shift;
|
|
if (index == 0)
|
|
goto out; /* 32-bit wraparound */
|
|
i++;
|
|
if (i == RADIX_TREE_MAP_SIZE)
|
|
goto out;
|
|
}
|
|
height--;
|
|
if (height == 0) { /* Bottom level: grab some items */
|
|
unsigned long j = index & RADIX_TREE_MAP_MASK;
|
|
|
|
for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
|
|
struct radix_tree_node *node;
|
|
index++;
|
|
if (!tag_get(slot, tag, j))
|
|
continue;
|
|
node = slot->slots[j];
|
|
/*
|
|
* Even though the tag was found set, we need to
|
|
* recheck that we have a non-NULL node, because
|
|
* if this lookup is lockless, it may have been
|
|
* subsequently deleted.
|
|
*
|
|
* Similar care must be taken in any place that
|
|
* lookup ->slots[x] without a lock (ie. can't
|
|
* rely on its value remaining the same).
|
|
*/
|
|
if (node) {
|
|
node = rcu_dereference(node);
|
|
results[nr_found++] = node;
|
|
if (nr_found == max_items)
|
|
goto out;
|
|
}
|
|
}
|
|
}
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
slot = rcu_dereference(slot->slots[i]);
|
|
if (slot == NULL)
|
|
break;
|
|
}
|
|
out:
|
|
*next_index = index;
|
|
return nr_found;
|
|
}
|
|
|
|
/**
|
|
* radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
|
|
* based on a tag
|
|
* @root: radix tree root
|
|
* @results: where the results of the lookup are placed
|
|
* @first_index: start the lookup from this key
|
|
* @max_items: place up to this many items at *results
|
|
* @tag: the tag index (< RADIX_TREE_MAX_TAGS)
|
|
*
|
|
* Performs an index-ascending scan of the tree for present items which
|
|
* have the tag indexed by @tag set. Places the items at *@results and
|
|
* returns the number of items which were placed at *@results.
|
|
*/
|
|
unsigned int
|
|
radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
|
|
unsigned long first_index, unsigned int max_items,
|
|
unsigned int tag)
|
|
{
|
|
struct radix_tree_node *node;
|
|
unsigned long max_index;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
/* check the root's tag bit */
|
|
if (!root_tag_get(root, tag))
|
|
return 0;
|
|
|
|
node = rcu_dereference(root->rnode);
|
|
if (!node)
|
|
return 0;
|
|
|
|
if (radix_tree_is_direct_ptr(node)) {
|
|
if (first_index > 0)
|
|
return 0;
|
|
node = radix_tree_direct_to_ptr(node);
|
|
results[0] = rcu_dereference(node);
|
|
return 1;
|
|
}
|
|
|
|
max_index = radix_tree_maxindex(node->height);
|
|
|
|
ret = 0;
|
|
while (ret < max_items) {
|
|
unsigned int nr_found;
|
|
unsigned long next_index; /* Index of next search */
|
|
|
|
if (cur_index > max_index)
|
|
break;
|
|
nr_found = __lookup_tag(node, results + ret, cur_index,
|
|
max_items - ret, &next_index, tag);
|
|
ret += nr_found;
|
|
if (next_index == 0)
|
|
break;
|
|
cur_index = next_index;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
|
|
|
|
/**
|
|
* radix_tree_shrink - shrink height of a radix tree to minimal
|
|
* @root radix tree root
|
|
*/
|
|
static inline void radix_tree_shrink(struct radix_tree_root *root)
|
|
{
|
|
/* try to shrink tree height */
|
|
while (root->height > 0 &&
|
|
root->rnode->count == 1 &&
|
|
root->rnode->slots[0]) {
|
|
struct radix_tree_node *to_free = root->rnode;
|
|
void *newptr;
|
|
|
|
/*
|
|
* We don't need rcu_assign_pointer(), since we are simply
|
|
* moving the node from one part of the tree to another. If
|
|
* it was safe to dereference the old pointer to it
|
|
* (to_free->slots[0]), it will be safe to dereference the new
|
|
* one (root->rnode).
|
|
*/
|
|
newptr = to_free->slots[0];
|
|
if (root->height == 1)
|
|
newptr = radix_tree_ptr_to_direct(newptr);
|
|
root->rnode = newptr;
|
|
root->height--;
|
|
/* must only free zeroed nodes into the slab */
|
|
tag_clear(to_free, 0, 0);
|
|
tag_clear(to_free, 1, 0);
|
|
to_free->slots[0] = NULL;
|
|
to_free->count = 0;
|
|
radix_tree_node_free(to_free);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* radix_tree_delete - delete an item from a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
*
|
|
* Remove the item at @index from the radix tree rooted at @root.
|
|
*
|
|
* Returns the address of the deleted item, or NULL if it was not present.
|
|
*/
|
|
void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
|
|
{
|
|
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
|
|
struct radix_tree_node *slot = NULL;
|
|
struct radix_tree_node *to_free;
|
|
unsigned int height, shift;
|
|
int tag;
|
|
int offset;
|
|
|
|
height = root->height;
|
|
if (index > radix_tree_maxindex(height))
|
|
goto out;
|
|
|
|
slot = root->rnode;
|
|
if (height == 0 && root->rnode) {
|
|
slot = radix_tree_direct_to_ptr(slot);
|
|
root_tag_clear_all(root);
|
|
root->rnode = NULL;
|
|
goto out;
|
|
}
|
|
|
|
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
|
pathp->node = NULL;
|
|
|
|
do {
|
|
if (slot == NULL)
|
|
goto out;
|
|
|
|
pathp++;
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
pathp->offset = offset;
|
|
pathp->node = slot;
|
|
slot = slot->slots[offset];
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
height--;
|
|
} while (height > 0);
|
|
|
|
if (slot == NULL)
|
|
goto out;
|
|
|
|
/*
|
|
* Clear all tags associated with the just-deleted item
|
|
*/
|
|
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
|
if (tag_get(pathp->node, tag, pathp->offset))
|
|
radix_tree_tag_clear(root, index, tag);
|
|
}
|
|
|
|
to_free = NULL;
|
|
/* Now free the nodes we do not need anymore */
|
|
while (pathp->node) {
|
|
pathp->node->slots[pathp->offset] = NULL;
|
|
pathp->node->count--;
|
|
/*
|
|
* Queue the node for deferred freeing after the
|
|
* last reference to it disappears (set NULL, above).
|
|
*/
|
|
if (to_free)
|
|
radix_tree_node_free(to_free);
|
|
|
|
if (pathp->node->count) {
|
|
if (pathp->node == root->rnode)
|
|
radix_tree_shrink(root);
|
|
goto out;
|
|
}
|
|
|
|
/* Node with zero slots in use so free it */
|
|
to_free = pathp->node;
|
|
pathp--;
|
|
|
|
}
|
|
root_tag_clear_all(root);
|
|
root->height = 0;
|
|
root->rnode = NULL;
|
|
if (to_free)
|
|
radix_tree_node_free(to_free);
|
|
|
|
out:
|
|
return slot;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_delete);
|
|
|
|
/**
|
|
* radix_tree_tagged - test whether any items in the tree are tagged
|
|
* @root: radix tree root
|
|
* @tag: tag to test
|
|
*/
|
|
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
|
|
{
|
|
return root_tag_get(root, tag);
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tagged);
|
|
|
|
static void
|
|
radix_tree_node_ctor(void *node, struct kmem_cache *cachep, unsigned long flags)
|
|
{
|
|
memset(node, 0, sizeof(struct radix_tree_node));
|
|
}
|
|
|
|
static __init unsigned long __maxindex(unsigned int height)
|
|
{
|
|
unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
|
|
unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
|
|
|
|
if (tmp >= RADIX_TREE_INDEX_BITS)
|
|
index = ~0UL;
|
|
return index;
|
|
}
|
|
|
|
static __init void radix_tree_init_maxindex(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
|
|
height_to_maxindex[i] = __maxindex(i);
|
|
}
|
|
|
|
static int radix_tree_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
int cpu = (long)hcpu;
|
|
struct radix_tree_preload *rtp;
|
|
|
|
/* Free per-cpu pool of perloaded nodes */
|
|
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
|
|
rtp = &per_cpu(radix_tree_preloads, cpu);
|
|
while (rtp->nr) {
|
|
kmem_cache_free(radix_tree_node_cachep,
|
|
rtp->nodes[rtp->nr-1]);
|
|
rtp->nodes[rtp->nr-1] = NULL;
|
|
rtp->nr--;
|
|
}
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
void __init radix_tree_init(void)
|
|
{
|
|
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
|
|
sizeof(struct radix_tree_node), 0,
|
|
SLAB_PANIC, radix_tree_node_ctor, NULL);
|
|
radix_tree_init_maxindex();
|
|
hotcpu_notifier(radix_tree_callback, 0);
|
|
}
|