radix-tree.c 39.2 KB
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/*
 * Copyright (C) 2001 Momchil Velikov
 * Portions Copyright (C) 2001 Christoph Hellwig
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 * Copyright (C) 2005 SGI, Christoph Lameter
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 * Copyright (C) 2006 Nick Piggin
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 * Copyright (C) 2012 Konstantin Khlebnikov
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 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/radix-tree.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/string.h>
#include <linux/bitops.h>
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#include <linux/rcupdate.h>
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#include <linux/hardirq.h>		/* in_interrupt() */
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/*
 * The height_to_maxindex array needs to be one deeper than the maximum
 * path as height 0 holds only 1 entry.
 */
static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
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/*
 * Radix tree node cache.
 */
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static struct kmem_cache *radix_tree_node_cachep;
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/*
 * The radix tree is variable-height, so an insert operation not only has
 * to build the branch to its corresponding item, it also has to build the
 * branch to existing items if the size has to be increased (by
 * radix_tree_extend).
 *
 * The worst case is a zero height tree with just a single item at index 0,
 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
 * Hence:
 */
#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)

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/*
 * Per-cpu pool of preloaded nodes
 */
struct radix_tree_preload {
	int nr;
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	struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE];
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};
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static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
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static inline void *ptr_to_indirect(void *ptr)
{
	return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
}

static inline void *indirect_to_ptr(void *ptr)
{
	return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
}

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static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
{
	return root->gfp_mask & __GFP_BITS_MASK;
}

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static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	__set_bit(offset, node->tags[tag]);
}

static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	__clear_bit(offset, node->tags[tag]);
}

static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
		int offset)
{
	return test_bit(offset, node->tags[tag]);
}

static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
{
	root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
}

static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
{
	root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
}

static inline void root_tag_clear_all(struct radix_tree_root *root)
{
	root->gfp_mask &= __GFP_BITS_MASK;
}

static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
{
	return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
}

/*
 * Returns 1 if any slot in the node has this tag set.
 * Otherwise returns 0.
 */
static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
{
	int idx;
	for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
		if (node->tags[tag][idx])
			return 1;
	}
	return 0;
}
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/**
 * radix_tree_find_next_bit - find the next set bit in a memory region
 *
 * @addr: The address to base the search on
 * @size: The bitmap size in bits
 * @offset: The bitnumber to start searching at
 *
 * Unrollable variant of find_next_bit() for constant size arrays.
 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
 * Returns next bit offset, or size if nothing found.
 */
static __always_inline unsigned long
radix_tree_find_next_bit(const unsigned long *addr,
			 unsigned long size, unsigned long offset)
{
	if (!__builtin_constant_p(size))
		return find_next_bit(addr, size, offset);

	if (offset < size) {
		unsigned long tmp;

		addr += offset / BITS_PER_LONG;
		tmp = *addr >> (offset % BITS_PER_LONG);
		if (tmp)
			return __ffs(tmp) + offset;
		offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
		while (offset < size) {
			tmp = *++addr;
			if (tmp)
				return __ffs(tmp) + offset;
			offset += BITS_PER_LONG;
		}
	}
	return size;
}

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/*
 * This assumes that the caller has performed appropriate preallocation, and
 * that the caller has pinned this thread of control to the current CPU.
 */
static struct radix_tree_node *
radix_tree_node_alloc(struct radix_tree_root *root)
{
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	struct radix_tree_node *ret = NULL;
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	gfp_t gfp_mask = root_gfp_mask(root);
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	/*
	 * Preload code isn't irq safe and it doesn't make sence to use
	 * preloading in the interrupt anyway as all the allocations have to
	 * be atomic. So just do normal allocation when in interrupt.
	 */
	if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) {
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		struct radix_tree_preload *rtp;

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		/*
		 * Provided the caller has preloaded here, we will always
		 * succeed in getting a node here (and never reach
		 * kmem_cache_alloc)
		 */
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		rtp = &__get_cpu_var(radix_tree_preloads);
		if (rtp->nr) {
			ret = rtp->nodes[rtp->nr - 1];
			rtp->nodes[rtp->nr - 1] = NULL;
			rtp->nr--;
		}
	}
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	if (ret == NULL)
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		ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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	BUG_ON(radix_tree_is_indirect_ptr(ret));
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	return ret;
}

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static void radix_tree_node_rcu_free(struct rcu_head *head)
{
	struct radix_tree_node *node =
			container_of(head, struct radix_tree_node, rcu_head);
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	int i;
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	/*
	 * must only free zeroed nodes into the slab. radix_tree_shrink
	 * can leave us with a non-NULL entry in the first slot, so clear
	 * that here to make sure.
	 */
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	for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
		tag_clear(node, i, 0);

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	node->slots[0] = NULL;
	node->count = 0;

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	kmem_cache_free(radix_tree_node_cachep, node);
}

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static inline void
radix_tree_node_free(struct radix_tree_node *node)
{
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	call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
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}

/*
 * Load up this CPU's radix_tree_node buffer with sufficient objects to
 * ensure that the addition of a single element in the tree cannot fail.  On
 * success, return zero, with preemption disabled.  On error, return -ENOMEM
 * with preemption not disabled.
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 *
 * To make use of this facility, the radix tree must be initialised without
 * __GFP_WAIT being passed to INIT_RADIX_TREE().
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 */
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static int __radix_tree_preload(gfp_t gfp_mask)
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{
	struct radix_tree_preload *rtp;
	struct radix_tree_node *node;
	int ret = -ENOMEM;

	preempt_disable();
	rtp = &__get_cpu_var(radix_tree_preloads);
	while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
		preempt_enable();
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		node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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		if (node == NULL)
			goto out;
		preempt_disable();
		rtp = &__get_cpu_var(radix_tree_preloads);
		if (rtp->nr < ARRAY_SIZE(rtp->nodes))
			rtp->nodes[rtp->nr++] = node;
		else
			kmem_cache_free(radix_tree_node_cachep, node);
	}
	ret = 0;
out:
	return ret;
}
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/*
 * Load up this CPU's radix_tree_node buffer with sufficient objects to
 * ensure that the addition of a single element in the tree cannot fail.  On
 * success, return zero, with preemption disabled.  On error, return -ENOMEM
 * with preemption not disabled.
 *
 * To make use of this facility, the radix tree must be initialised without
 * __GFP_WAIT being passed to INIT_RADIX_TREE().
 */
int radix_tree_preload(gfp_t gfp_mask)
{
	/* Warn on non-sensical use... */
	WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT));
	return __radix_tree_preload(gfp_mask);
}
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EXPORT_SYMBOL(radix_tree_preload);
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/*
 * The same as above function, except we don't guarantee preloading happens.
 * We do it, if we decide it helps. On success, return zero with preemption
 * disabled. On error, return -ENOMEM with preemption not disabled.
 */
int radix_tree_maybe_preload(gfp_t gfp_mask)
{
	if (gfp_mask & __GFP_WAIT)
		return __radix_tree_preload(gfp_mask);
	/* Preloading doesn't help anything with this gfp mask, skip it */
	preempt_disable();
	return 0;
}
EXPORT_SYMBOL(radix_tree_maybe_preload);

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/*
 *	Return the maximum key which can be store into a
 *	radix tree with height HEIGHT.
 */
static inline unsigned long radix_tree_maxindex(unsigned int height)
{
	return height_to_maxindex[height];
}

/*
 *	Extend a radix tree so it can store key @index.
 */
static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
{
	struct radix_tree_node *node;
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	struct radix_tree_node *slot;
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	unsigned int height;
	int tag;

	/* Figure out what the height should be.  */
	height = root->height + 1;
	while (index > radix_tree_maxindex(height))
		height++;

	if (root->rnode == NULL) {
		root->height = height;
		goto out;
	}

	do {
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		unsigned int newheight;
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		if (!(node = radix_tree_node_alloc(root)))
			return -ENOMEM;

		/* 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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		/* Increase the height.  */
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		newheight = root->height+1;
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		BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK);
		node->path = newheight;
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		node->count = 1;
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		node->parent = NULL;
		slot = root->rnode;
		if (newheight > 1) {
			slot = indirect_to_ptr(slot);
			slot->parent = node;
		}
		node->slots[0] = slot;
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		node = ptr_to_indirect(node);
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		rcu_assign_pointer(root->rnode, node);
		root->height = newheight;
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	} while (height > root->height);
out:
	return 0;
}

/**
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 *	__radix_tree_create	-	create a slot in a radix tree
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 *	@root:		radix tree root
 *	@index:		index key
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 *	@nodep:		returns node
 *	@slotp:		returns slot
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 *
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 *	Create, if necessary, and return the node and slot for an item
 *	at position @index in the radix tree @root.
 *
 *	Until there is more than one item in the tree, no nodes are
 *	allocated and @root->rnode is used as a direct slot instead of
 *	pointing to a node, in which case *@nodep will be NULL.
 *
 *	Returns -ENOMEM, or 0 for success.
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 */
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int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
			struct radix_tree_node **nodep, void ***slotp)
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{
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	struct radix_tree_node *node = NULL, *slot;
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	unsigned int height, shift, offset;
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	int error;

	/* 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);
		if (error)
			return error;
	}

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	slot = indirect_to_ptr(root->rnode);
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	height = root->height;
	shift = (height-1) * RADIX_TREE_MAP_SHIFT;

	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->path = height;
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			slot->parent = node;
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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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				slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT;
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			} else
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				rcu_assign_pointer(root->rnode, ptr_to_indirect(slot));
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		}

		/* Go a level down */
		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
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		node = slot;
		slot = node->slots[offset];
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		shift -= RADIX_TREE_MAP_SHIFT;
		height--;
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	}
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	if (nodep)
		*nodep = node;
	if (slotp)
		*slotp = node ? node->slots + offset : (void **)&root->rnode;
	return 0;
}

/**
 *	radix_tree_insert    -    insert into a radix tree
 *	@root:		radix tree root
 *	@index:		index key
 *	@item:		item to insert
 *
 *	Insert an item into the radix tree at position @index.
 */
int radix_tree_insert(struct radix_tree_root *root,
			unsigned long index, void *item)
{
	struct radix_tree_node *node;
	void **slot;
	int error;

	BUG_ON(radix_tree_is_indirect_ptr(item));

	error = __radix_tree_create(root, index, &node, &slot);
	if (error)
		return error;
	if (*slot != NULL)
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		return -EEXIST;
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	rcu_assign_pointer(*slot, item);
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	if (node) {
		node->count++;
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		BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
		BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
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	} else {
		BUG_ON(root_tag_get(root, 0));
		BUG_ON(root_tag_get(root, 1));
	}
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	return 0;
}
EXPORT_SYMBOL(radix_tree_insert);

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/**
 *	__radix_tree_lookup	-	lookup an item in a radix tree
 *	@root:		radix tree root
 *	@index:		index key
 *	@nodep:		returns node
 *	@slotp:		returns slot
 *
 *	Lookup and return the item at position @index in the radix
 *	tree @root.
 *
 *	Until there is more than one item in the tree, no nodes are
 *	allocated and @root->rnode is used as a direct slot instead of
 *	pointing to a node, in which case *@nodep will be NULL.
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 */
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void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
			  struct radix_tree_node **nodep, void ***slotp)
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{
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	struct radix_tree_node *node, *parent;
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	unsigned int height, shift;
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	void **slot;
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	node = rcu_dereference_raw(root->rnode);
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	if (node == NULL)
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		return NULL;

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	if (!radix_tree_is_indirect_ptr(node)) {
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		if (index > 0)
			return NULL;
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		if (nodep)
			*nodep = NULL;
		if (slotp)
			*slotp = (void **)&root->rnode;
		return node;
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	}
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	node = indirect_to_ptr(node);
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	height = node->path & RADIX_TREE_HEIGHT_MASK;
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	if (index > radix_tree_maxindex(height))
		return NULL;
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	shift = (height-1) * RADIX_TREE_MAP_SHIFT;

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	do {
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		parent = node;
		slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK);
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		node = rcu_dereference_raw(*slot);
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		if (node == NULL)
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			return NULL;

		shift -= RADIX_TREE_MAP_SHIFT;
		height--;
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	} while (height > 0);
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	if (nodep)
		*nodep = parent;
	if (slotp)
		*slotp = slot;
	return node;
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}

/**
 *	radix_tree_lookup_slot    -    lookup a slot in a radix tree
 *	@root:		radix tree root
 *	@index:		index key
 *
 *	Returns:  the slot corresponding to the position @index in the
 *	radix tree @root. This is useful for update-if-exists operations.
 *
 *	This function can be called under rcu_read_lock iff the slot is not
 *	modified by radix_tree_replace_slot, otherwise it must be called
 *	exclusive from other writers. Any dereference of the slot must be done
 *	using radix_tree_deref_slot.
 */
void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
{
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	void **slot;

	if (!__radix_tree_lookup(root, index, NULL, &slot))
		return NULL;
	return slot;
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}
EXPORT_SYMBOL(radix_tree_lookup_slot);

/**
 *	radix_tree_lookup    -    perform lookup operation on a radix tree
 *	@root:		radix tree root
 *	@index:		index key
 *
 *	Lookup the item at the position @index in the radix tree @root.
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 *
 *	This function can be called under rcu_read_lock, however the caller
 *	must manage lifetimes of leaf nodes (eg. RCU may also be used to free
 *	them safely). No RCU barriers are required to access or modify the
 *	returned item, however.
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 */
void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{
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	return __radix_tree_lookup(root, index, NULL, NULL);
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}
EXPORT_SYMBOL(radix_tree_lookup);

/**
 *	radix_tree_tag_set - set a tag on a radix tree node
 *	@root:		radix tree root
 *	@index:		index key
 *	@tag: 		tag index
 *
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 *	Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
 *	corresponding to @index in the radix tree.  From
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 *	the root all the way down to the leaf node.
 *
 *	Returns the address of the tagged item.   Setting a tag on a not-present
 *	item is a bug.
 */
void *radix_tree_tag_set(struct radix_tree_root *root,
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			unsigned long index, unsigned int tag)
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{
	unsigned int height, shift;
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	struct radix_tree_node *slot;
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	height = root->height;
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	BUG_ON(index > radix_tree_maxindex(height));
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	slot = indirect_to_ptr(root->rnode);
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591
	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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	while (height > 0) {
		int offset;

		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
597 598
		if (!tag_get(slot, tag, offset))
			tag_set(slot, tag, offset);
599 600
		slot = slot->slots[offset];
		BUG_ON(slot == NULL);
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		shift -= RADIX_TREE_MAP_SHIFT;
		height--;
	}

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	/* set the root's tag bit */
	if (slot && !root_tag_get(root, tag))
		root_tag_set(root, tag);

609
	return slot;
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}
EXPORT_SYMBOL(radix_tree_tag_set);

/**
 *	radix_tree_tag_clear - clear a tag on a radix tree node
 *	@root:		radix tree root
 *	@index:		index key
 *	@tag: 		tag index
 *
619 620
 *	Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
 *	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
 *	next-to-leaf node, etc.
 *
 *	Returns the address of the tagged item on success, else NULL.  ie:
 *	has the same return value and semantics as radix_tree_lookup().
 */
void *radix_tree_tag_clear(struct radix_tree_root *root,
628
			unsigned long index, unsigned int tag)
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629
{
630
	struct radix_tree_node *node = NULL;
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631
	struct radix_tree_node *slot = NULL;
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632
	unsigned int height, shift;
633
	int uninitialized_var(offset);
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634 635 636 637 638

	height = root->height;
	if (index > radix_tree_maxindex(height))
		goto out;

639
	shift = height * RADIX_TREE_MAP_SHIFT;
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640
	slot = indirect_to_ptr(root->rnode);
L
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641

642
	while (shift) {
643
		if (slot == NULL)
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644 645
			goto out;

646
		shift -= RADIX_TREE_MAP_SHIFT;
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647
		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
648
		node = slot;
649
		slot = slot->slots[offset];
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650 651
	}

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652
	if (slot == NULL)
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		goto out;

655 656
	while (node) {
		if (!tag_get(node, tag, offset))
657
			goto out;
658 659
		tag_clear(node, tag, offset);
		if (any_tag_set(node, tag))
660
			goto out;
661 662 663 664

		index >>= RADIX_TREE_MAP_SHIFT;
		offset = index & RADIX_TREE_MAP_MASK;
		node = node->parent;
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	}

	/* clear the root's tag bit */
	if (root_tag_get(root, tag))
		root_tag_clear(root, tag);

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out:
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672
	return slot;
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673 674 675 676
}
EXPORT_SYMBOL(radix_tree_tag_clear);

/**
677 678 679
 * radix_tree_tag_get - get a tag on a radix tree node
 * @root:		radix tree root
 * @index:		index key
680
 * @tag: 		tag index (< RADIX_TREE_MAX_TAGS)
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 *
682
 * Return values:
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683
 *
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684 685
 *  0: tag not present or not set
 *  1: tag set
686 687 688 689
 *
 * Note that the return value of this function may not be relied on, even if
 * the RCU lock is held, unless tag modification and node deletion are excluded
 * from concurrency.
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 */
int radix_tree_tag_get(struct radix_tree_root *root,
692
			unsigned long index, unsigned int tag)
L
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693 694
{
	unsigned int height, shift;
695
	struct radix_tree_node *node;
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696

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	/* check the root's tag bit */
	if (!root_tag_get(root, tag))
		return 0;

701
	node = rcu_dereference_raw(root->rnode);
702 703 704
	if (node == NULL)
		return 0;

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705
	if (!radix_tree_is_indirect_ptr(node))
706
		return (index == 0);
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707
	node = indirect_to_ptr(node);
708

709
	height = node->path & RADIX_TREE_HEIGHT_MASK;
710 711
	if (index > radix_tree_maxindex(height))
		return 0;
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713 714 715 716 717
	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;

	for ( ; ; ) {
		int offset;

718
		if (node == NULL)
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			return 0;

		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
722
		if (!tag_get(node, tag, offset))
723
			return 0;
724
		if (height == 1)
725
			return 1;
726
		node = rcu_dereference_raw(node->slots[offset]);
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		shift -= RADIX_TREE_MAP_SHIFT;
		height--;
	}
}
EXPORT_SYMBOL(radix_tree_tag_get);

733 734 735 736 737 738 739 740 741 742 743 744 745
/**
 * radix_tree_next_chunk - find next chunk of slots for iteration
 *
 * @root:	radix tree root
 * @iter:	iterator state
 * @flags:	RADIX_TREE_ITER_* flags and tag index
 * Returns:	pointer to chunk first slot, or NULL if iteration is over
 */
void **radix_tree_next_chunk(struct radix_tree_root *root,
			     struct radix_tree_iter *iter, unsigned flags)
{
	unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
	struct radix_tree_node *rnode, *node;
746
	unsigned long index, offset, height;
747 748 749 750 751 752 753 754 755

	if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
		return NULL;

	/*
	 * Catch next_index overflow after ~0UL. iter->index never overflows
	 * during iterating; it can be zero only at the beginning.
	 * And we cannot overflow iter->next_index in a single step,
	 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
756 757 758
	 *
	 * This condition also used by radix_tree_next_slot() to stop
	 * contiguous iterating, and forbid swithing to the next chunk.
759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776
	 */
	index = iter->next_index;
	if (!index && iter->index)
		return NULL;

	rnode = rcu_dereference_raw(root->rnode);
	if (radix_tree_is_indirect_ptr(rnode)) {
		rnode = indirect_to_ptr(rnode);
	} else if (rnode && !index) {
		/* Single-slot tree */
		iter->index = 0;
		iter->next_index = 1;
		iter->tags = 1;
		return (void **)&root->rnode;
	} else
		return NULL;

restart:
777 778
	height = rnode->path & RADIX_TREE_HEIGHT_MASK;
	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849
	offset = index >> shift;

	/* Index outside of the tree */
	if (offset >= RADIX_TREE_MAP_SIZE)
		return NULL;

	node = rnode;
	while (1) {
		if ((flags & RADIX_TREE_ITER_TAGGED) ?
				!test_bit(offset, node->tags[tag]) :
				!node->slots[offset]) {
			/* Hole detected */
			if (flags & RADIX_TREE_ITER_CONTIG)
				return NULL;

			if (flags & RADIX_TREE_ITER_TAGGED)
				offset = radix_tree_find_next_bit(
						node->tags[tag],
						RADIX_TREE_MAP_SIZE,
						offset + 1);
			else
				while (++offset	< RADIX_TREE_MAP_SIZE) {
					if (node->slots[offset])
						break;
				}
			index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
			index += offset << shift;
			/* Overflow after ~0UL */
			if (!index)
				return NULL;
			if (offset == RADIX_TREE_MAP_SIZE)
				goto restart;
		}

		/* This is leaf-node */
		if (!shift)
			break;

		node = rcu_dereference_raw(node->slots[offset]);
		if (node == NULL)
			goto restart;
		shift -= RADIX_TREE_MAP_SHIFT;
		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
	}

	/* Update the iterator state */
	iter->index = index;
	iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1;

	/* Construct iter->tags bit-mask from node->tags[tag] array */
	if (flags & RADIX_TREE_ITER_TAGGED) {
		unsigned tag_long, tag_bit;

		tag_long = offset / BITS_PER_LONG;
		tag_bit  = offset % BITS_PER_LONG;
		iter->tags = node->tags[tag][tag_long] >> tag_bit;
		/* This never happens if RADIX_TREE_TAG_LONGS == 1 */
		if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
			/* Pick tags from next element */
			if (tag_bit)
				iter->tags |= node->tags[tag][tag_long + 1] <<
						(BITS_PER_LONG - tag_bit);
			/* Clip chunk size, here only BITS_PER_LONG tags */
			iter->next_index = index + BITS_PER_LONG;
		}
	}

	return node->slots + offset;
}
EXPORT_SYMBOL(radix_tree_next_chunk);

850 851 852 853 854 855 856 857 858 859 860 861 862 863 864
/**
 * radix_tree_range_tag_if_tagged - for each item in given range set given
 *				   tag if item has another tag set
 * @root:		radix tree root
 * @first_indexp:	pointer to a starting index of a range to scan
 * @last_index:		last index of a range to scan
 * @nr_to_tag:		maximum number items to tag
 * @iftag:		tag index to test
 * @settag:		tag index to set if tested tag is set
 *
 * This function scans range of radix tree from first_index to last_index
 * (inclusive).  For each item in the range if iftag is set, the function sets
 * also settag. The function stops either after tagging nr_to_tag items or
 * after reaching last_index.
 *
865 866 867 868 869 870 871
 * The tags must be set from the leaf level only and propagated back up the
 * path to the root. We must do this so that we resolve the full path before
 * setting any tags on intermediate nodes. If we set tags as we descend, then
 * we can get to the leaf node and find that the index that has the iftag
 * set is outside the range we are scanning. This reults in dangling tags and
 * can lead to problems with later tag operations (e.g. livelocks on lookups).
 *
872 873
 * The function returns number of leaves where the tag was set and sets
 * *first_indexp to the first unscanned index.
874 875
 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
 * be prepared to handle that.
876 877 878 879 880 881
 */
unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
		unsigned long *first_indexp, unsigned long last_index,
		unsigned long nr_to_tag,
		unsigned int iftag, unsigned int settag)
{
882
	unsigned int height = root->height;
883
	struct radix_tree_node *node = NULL;
884 885 886 887
	struct radix_tree_node *slot;
	unsigned int shift;
	unsigned long tagged = 0;
	unsigned long index = *first_indexp;
888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904

	last_index = min(last_index, radix_tree_maxindex(height));
	if (index > last_index)
		return 0;
	if (!nr_to_tag)
		return 0;
	if (!root_tag_get(root, iftag)) {
		*first_indexp = last_index + 1;
		return 0;
	}
	if (height == 0) {
		*first_indexp = last_index + 1;
		root_tag_set(root, settag);
		return 1;
	}

	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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905
	slot = indirect_to_ptr(root->rnode);
906 907

	for (;;) {
908
		unsigned long upindex;
909 910 911 912 913 914 915
		int offset;

		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
		if (!slot->slots[offset])
			goto next;
		if (!tag_get(slot, iftag, offset))
			goto next;
916
		if (shift) {
917 918
			/* Go down one level */
			shift -= RADIX_TREE_MAP_SHIFT;
919
			node = slot;
920 921 922 923 924 925
			slot = slot->slots[offset];
			continue;
		}

		/* tag the leaf */
		tagged++;
926
		tag_set(slot, settag, offset);
927 928

		/* walk back up the path tagging interior nodes */
929 930 931 932 933
		upindex = index;
		while (node) {
			upindex >>= RADIX_TREE_MAP_SHIFT;
			offset = upindex & RADIX_TREE_MAP_MASK;

934
			/* stop if we find a node with the tag already set */
935
			if (tag_get(node, settag, offset))
936
				break;
937 938
			tag_set(node, settag, offset);
			node = node->parent;
939
		}
940

941 942 943 944 945 946 947 948 949
		/*
		 * Small optimization: now clear that node pointer.
		 * Since all of this slot's ancestors now have the tag set
		 * from setting it above, we have no further need to walk
		 * back up the tree setting tags, until we update slot to
		 * point to another radix_tree_node.
		 */
		node = NULL;

950 951 952
next:
		/* Go to next item at level determined by 'shift' */
		index = ((index >> shift) + 1) << shift;
953 954
		/* Overflow can happen when last_index is ~0UL... */
		if (index > last_index || !index)
955 956 957 958 959 960 961 962 963
			break;
		if (tagged >= nr_to_tag)
			break;
		while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
			/*
			 * We've fully scanned this node. Go up. Because
			 * last_index is guaranteed to be in the tree, what
			 * we do below cannot wander astray.
			 */
964
			slot = slot->parent;
965 966 967 968
			shift += RADIX_TREE_MAP_SHIFT;
		}
	}
	/*
969 970
	 * We need not to tag the root tag if there is no tag which is set with
	 * settag within the range from *first_indexp to last_index.
971
	 */
972 973
	if (tagged > 0)
		root_tag_set(root, settag);
974 975 976 977 978 979
	*first_indexp = index;

	return tagged;
}
EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);

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980 981 982 983 984 985 986 987 988 989 990 991
/**
 *	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.
992 993 994 995 996 997
 *
 *	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'.
L
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 */
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
			unsigned long first_index, unsigned int max_items)
{
1003 1004 1005
	struct radix_tree_iter iter;
	void **slot;
	unsigned int ret = 0;
1006

1007
	if (unlikely(!max_items))
1008
		return 0;
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1009

1010 1011 1012 1013 1014
	radix_tree_for_each_slot(slot, root, &iter, first_index) {
		results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
		if (!results[ret])
			continue;
		if (++ret == max_items)
L
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1015 1016
			break;
	}
1017

L
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1018 1019 1020 1021
	return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup);

1022 1023 1024 1025
/**
 *	radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
 *	@root:		radix tree root
 *	@results:	where the results of the lookup are placed
1026
 *	@indices:	where their indices should be placed (but usually NULL)
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
 *	@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
 *	their slots at *@results and returns the number of items which were
 *	placed at *@results.
 *
 *	The implementation is naive.
 *
 *	Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
 *	be dereferenced with radix_tree_deref_slot, and if using only RCU
 *	protection, radix_tree_deref_slot may fail requiring a retry.
 */
unsigned int
1041 1042
radix_tree_gang_lookup_slot(struct radix_tree_root *root,
			void ***results, unsigned long *indices,
1043 1044
			unsigned long first_index, unsigned int max_items)
{
1045 1046 1047
	struct radix_tree_iter iter;
	void **slot;
	unsigned int ret = 0;
1048

1049
	if (unlikely(!max_items))
1050 1051
		return 0;

1052 1053
	radix_tree_for_each_slot(slot, root, &iter, first_index) {
		results[ret] = slot;
1054
		if (indices)
1055 1056
			indices[ret] = iter.index;
		if (++ret == max_items)
1057 1058 1059 1060 1061 1062 1063
			break;
	}

	return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_slot);

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1064 1065 1066 1067 1068 1069 1070
/**
 *	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
1071
 *	@tag:		the tag index (< RADIX_TREE_MAX_TAGS)
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1072 1073 1074 1075 1076 1077 1078
 *
 *	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,
1079 1080
		unsigned long first_index, unsigned int max_items,
		unsigned int tag)
L
Linus Torvalds 已提交
1081
{
1082 1083 1084
	struct radix_tree_iter iter;
	void **slot;
	unsigned int ret = 0;
N
Nick Piggin 已提交
1085

1086
	if (unlikely(!max_items))
1087 1088
		return 0;

1089 1090 1091 1092 1093
	radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
		results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
		if (!results[ret])
			continue;
		if (++ret == max_items)
L
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1094 1095
			break;
	}
1096

L
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1097 1098 1099 1100
	return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_tag);

1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118
/**
 *	radix_tree_gang_lookup_tag_slot - perform multiple slot 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 slots at *@results and
 *	returns the number of slots which were placed at *@results.
 */
unsigned int
radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
		unsigned long first_index, unsigned int max_items,
		unsigned int tag)
{
1119 1120 1121
	struct radix_tree_iter iter;
	void **slot;
	unsigned int ret = 0;
1122

1123
	if (unlikely(!max_items))
1124 1125
		return 0;

1126 1127 1128
	radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
		results[ret] = slot;
		if (++ret == max_items)
1129 1130 1131 1132 1133 1134 1135
			break;
	}

	return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);

1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147
#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
#include <linux/sched.h> /* for cond_resched() */

/*
 * This linear search is at present only useful to shmem_unuse_inode().
 */
static unsigned long __locate(struct radix_tree_node *slot, void *item,
			      unsigned long index, unsigned long *found_index)
{
	unsigned int shift, height;
	unsigned long i;

1148
	height = slot->path & RADIX_TREE_HEIGHT_MASK;
1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210
	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_raw(slot->slots[i]);
		if (slot == NULL)
			goto out;
	}

	/* Bottom level: check items */
	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
		if (slot->slots[i] == item) {
			*found_index = index + i;
			index = 0;
			goto out;
		}
	}
	index += RADIX_TREE_MAP_SIZE;
out:
	return index;
}

/**
 *	radix_tree_locate_item - search through radix tree for item
 *	@root:		radix tree root
 *	@item:		item to be found
 *
 *	Returns index where item was found, or -1 if not found.
 *	Caller must hold no lock (since this time-consuming function needs
 *	to be preemptible), and must check afterwards if item is still there.
 */
unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
{
	struct radix_tree_node *node;
	unsigned long max_index;
	unsigned long cur_index = 0;
	unsigned long found_index = -1;

	do {
		rcu_read_lock();
		node = rcu_dereference_raw(root->rnode);
		if (!radix_tree_is_indirect_ptr(node)) {
			rcu_read_unlock();
			if (node == item)
				found_index = 0;
			break;
		}

		node = indirect_to_ptr(node);
1211 1212
		max_index = radix_tree_maxindex(node->path &
						RADIX_TREE_HEIGHT_MASK);
1213 1214
		if (cur_index > max_index) {
			rcu_read_unlock();
1215
			break;
1216
		}
1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230

		cur_index = __locate(node, item, cur_index, &found_index);
		rcu_read_unlock();
		cond_resched();
	} while (cur_index != 0 && cur_index <= max_index);

	return found_index;
}
#else
unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
{
	return -1;
}
#endif /* CONFIG_SHMEM && CONFIG_SWAP */
1231

1232 1233 1234 1235 1236 1237 1238
/**
 *	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 */
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	while (root->height > 0) {
1240
		struct radix_tree_node *to_free = root->rnode;
1241
		struct radix_tree_node *slot;
1242

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		BUG_ON(!radix_tree_is_indirect_ptr(to_free));
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		to_free = indirect_to_ptr(to_free);
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		/*
		 * The candidate node has more than one child, or its child
		 * is not at the leftmost slot, we cannot shrink.
		 */
		if (to_free->count != 1)
			break;
		if (!to_free->slots[0])
			break;

1255 1256
		/*
		 * We don't need rcu_assign_pointer(), since we are simply
N
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		 * moving the node from one part of the tree to another: if it
		 * was safe to dereference the old pointer to it
1259
		 * (to_free->slots[0]), it will be safe to dereference the new
N
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		 * one (root->rnode) as far as dependent read barriers go.
1261
		 */
1262 1263 1264 1265 1266 1267
		slot = to_free->slots[0];
		if (root->height > 1) {
			slot->parent = NULL;
			slot = ptr_to_indirect(slot);
		}
		root->rnode = slot;
1268
		root->height--;
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		/*
		 * We have a dilemma here. The node's slot[0] must not be
		 * NULLed in case there are concurrent lookups expecting to
		 * find the item. However if this was a bottom-level node,
		 * then it may be subject to the slot pointer being visible
		 * to callers dereferencing it. If item corresponding to
		 * slot[0] is subsequently deleted, these callers would expect
		 * their slot to become empty sooner or later.
		 *
		 * For example, lockless pagecache will look up a slot, deref
		 * the page pointer, and if the page is 0 refcount it means it
		 * was concurrently deleted from pagecache so try the deref
		 * again. Fortunately there is already a requirement for logic
		 * to retry the entire slot lookup -- the indirect pointer
		 * problem (replacing direct root node with an indirect pointer
		 * also results in a stale slot). So tag the slot as indirect
		 * to force callers to retry.
		 */
		if (root->height == 0)
			*((unsigned long *)&to_free->slots[0]) |=
						RADIX_TREE_INDIRECT_PTR;

1292 1293 1294 1295
		radix_tree_node_free(to_free);
	}
}

1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307
/**
 *	__radix_tree_delete_node    -    try to free node after clearing a slot
 *	@root:		radix tree root
 *	@index:		index key
 *	@node:		node containing @index
 *
 *	After clearing the slot at @index in @node from radix tree
 *	rooted at @root, call this function to attempt freeing the
 *	node and shrinking the tree.
 *
 *	Returns %true if @node was freed, %false otherwise.
 */
1308
bool __radix_tree_delete_node(struct radix_tree_root *root,
1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
			      struct radix_tree_node *node)
{
	bool deleted = false;

	do {
		struct radix_tree_node *parent;

		if (node->count) {
			if (node == indirect_to_ptr(root->rnode)) {
				radix_tree_shrink(root);
				if (root->height == 0)
					deleted = true;
			}
			return deleted;
		}

		parent = node->parent;
		if (parent) {
1327
			unsigned int offset;
1328

1329 1330
			offset = node->path >> RADIX_TREE_HEIGHT_SHIFT;
			parent->slots[offset] = NULL;
1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346
			parent->count--;
		} else {
			root_tag_clear_all(root);
			root->height = 0;
			root->rnode = NULL;
		}

		radix_tree_node_free(node);
		deleted = true;

		node = parent;
	} while (node);

	return deleted;
}

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/**
1348
 *	radix_tree_delete_item    -    delete an item from a radix tree
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 *	@root:		radix tree root
 *	@index:		index key
1351
 *	@item:		expected item
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 *
1353
 *	Remove @item at @index from the radix tree rooted at @root.
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 *
1355 1356
 *	Returns the address of the deleted item, or NULL if it was not present
 *	or the entry at the given @index was not @item.
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 */
1358 1359
void *radix_tree_delete_item(struct radix_tree_root *root,
			     unsigned long index, void *item)
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{
1361 1362 1363 1364
	struct radix_tree_node *node;
	unsigned int offset;
	void **slot;
	void *entry;
1365
	int tag;
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1367 1368 1369
	entry = __radix_tree_lookup(root, index, &node, &slot);
	if (!entry)
		return NULL;
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1371 1372 1373 1374
	if (item && entry != item)
		return NULL;

	if (!node) {
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		root_tag_clear_all(root);
		root->rnode = NULL;
1377
		return entry;
N
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	}
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1380
	offset = index & RADIX_TREE_MAP_MASK;
1381

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	/*
1383 1384
	 * Clear all tags associated with the item to be deleted.
	 * This way of doing it would be inefficient, but seldom is any set.
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	 */
1386
	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
1387
		if (tag_get(node, tag, offset))
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			radix_tree_tag_clear(root, index, tag);
1389
	}
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1391 1392
	node->slots[offset] = NULL;
	node->count--;
1393

1394
	__radix_tree_delete_node(root, node);
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1396
	return entry;
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}
1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412
EXPORT_SYMBOL(radix_tree_delete_item);

/**
 *	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)
{
	return radix_tree_delete_item(root, index, NULL);
}
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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
 */
1420
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
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{
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	return root_tag_get(root, tag);
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1423 1424 1425 1426
}
EXPORT_SYMBOL(radix_tree_tagged);

static void
1427
radix_tree_node_ctor(void *arg)
L
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{
1429 1430 1431 1432
	struct radix_tree_node *node = arg;

	memset(node, 0, sizeof(*node));
	INIT_LIST_HEAD(&node->private_list);
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1433 1434 1435 1436
}

static __init unsigned long __maxindex(unsigned int height)
{
1437 1438 1439 1440 1441 1442 1443 1444
	unsigned int width = height * RADIX_TREE_MAP_SHIFT;
	int shift = RADIX_TREE_INDEX_BITS - width;

	if (shift < 0)
		return ~0UL;
	if (shift >= BITS_PER_LONG)
		return 0UL;
	return ~0UL >> shift;
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1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462
}

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 */
1463
       if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
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1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478
               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,
C
Christoph Lameter 已提交
1479 1480
			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
			radix_tree_node_ctor);
L
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1481 1482 1483
	radix_tree_init_maxindex();
	hotcpu_notifier(radix_tree_callback, 0);
}