/*
* Copyright (C) 2001 Momchil Velikov
* Portions Copyright (C) 2001 Christoph Hellwig
+ * Copyright (C) 2005 SGI, Christoph Lameter
+ * Copyright (C) 2006 Nick Piggin
+ * Copyright (C) 2012 Konstantin Khlebnikov
*
* 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>
-#include <linux/mempool.h>
-#include <linux/module.h>
+#include <linux/export.h>
#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>
+#include <linux/rcupdate.h>
-/*
- * Radix tree node definition.
- */
-#define RADIX_TREE_MAP_SHIFT 6
-#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
-#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
+
+#ifdef __KERNEL__
+#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
+#else
+#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
+#endif
+
+#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
+#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
+
+#define RADIX_TREE_TAG_LONGS \
+ ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
struct radix_tree_node {
+ unsigned int height; /* Height from the bottom */
unsigned int count;
- void *slots[RADIX_TREE_MAP_SIZE];
-};
-
-struct radix_tree_path {
- struct radix_tree_node *node, **slot;
+ union {
+ struct radix_tree_node *parent; /* Used when ascending tree */
+ struct rcu_head rcu_head; /* Used when freeing node */
+ };
+ void __rcu *slots[RADIX_TREE_MAP_SIZE];
+ unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
};
#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
-#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
+ RADIX_TREE_MAP_SHIFT))
+
+/*
+ * 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;
/*
* Radix tree node cache.
*/
-static kmem_cache_t *radix_tree_node_cachep;
-static mempool_t *radix_tree_node_pool;
+static struct kmem_cache *radix_tree_node_cachep;
+
+/*
+ * Per-cpu pool of preloaded nodes
+ */
+struct radix_tree_preload {
+ int nr;
+ struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
+};
+static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+
+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);
+}
+
+static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
+{
+ return root->gfp_mask & __GFP_BITS_MASK;
+}
+
+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;
+}
+
+/**
+ * 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;
+}
-static inline struct radix_tree_node *
+/*
+ * 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)
{
- return mempool_alloc(radix_tree_node_pool, root->gfp_mask);
+ struct radix_tree_node *ret = NULL;
+ gfp_t gfp_mask = root_gfp_mask(root);
+
+ if (!(gfp_mask & __GFP_WAIT)) {
+ struct radix_tree_preload *rtp;
+
+ /*
+ * Provided the caller has preloaded here, we will always
+ * succeed in getting a node here (and never reach
+ * kmem_cache_alloc)
+ */
+ rtp = &__get_cpu_var(radix_tree_preloads);
+ if (rtp->nr) {
+ ret = rtp->nodes[rtp->nr - 1];
+ rtp->nodes[rtp->nr - 1] = NULL;
+ rtp->nr--;
+ }
+ }
+ if (ret == NULL)
+ ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
+
+ BUG_ON(radix_tree_is_indirect_ptr(ret));
+ return ret;
+}
+
+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);
+ int i;
+
+ /*
+ * 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.
+ */
+ for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
+ tag_clear(node, i, 0);
+
+ node->slots[0] = NULL;
+ node->count = 0;
+
+ kmem_cache_free(radix_tree_node_cachep, node);
}
static inline void
radix_tree_node_free(struct radix_tree_node *node)
{
- mempool_free(node, radix_tree_node_pool);
+ call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
}
/*
+ * 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)
+{
+ 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();
+ node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
+ 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;
+}
+EXPORT_SYMBOL(radix_tree_preload);
+
+/*
* 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)
{
- 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;
+ 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;
+ struct radix_tree_node *slot;
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) {
- do {
- if (!(node = radix_tree_node_alloc(root)))
- return -ENOMEM;
-
- /* Increase the height. */
- node->slots[0] = root->rnode;
- if (root->rnode)
- node->count = 1;
- root->rnode = node;
- root->height++;
- } while (height > root->height);
- } else
+ if (root->rnode == NULL) {
root->height = height;
+ goto out;
+ }
+
+ do {
+ unsigned int newheight;
+ if (!(node = radix_tree_node_alloc(root)))
+ return -ENOMEM;
+ /* Propagate the aggregated tag info into the new root */
+ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+ if (root_tag_get(root, tag))
+ tag_set(node, tag, 0);
+ }
+
+ /* Increase the height. */
+ newheight = root->height+1;
+ node->height = newheight;
+ node->count = 1;
+ node->parent = NULL;
+ slot = root->rnode;
+ if (newheight > 1) {
+ slot = indirect_to_ptr(slot);
+ slot->parent = node;
+ }
+ node->slots[0] = slot;
+ node = ptr_to_indirect(node);
+ rcu_assign_pointer(root->rnode, node);
+ root->height = newheight;
+ } while (height > root->height);
+out:
return 0;
}
-
/**
- * radix_tree_reserve - reserve space in a radix tree
+ * radix_tree_insert - insert into a radix tree
* @root: radix tree root
* @index: index key
- * @pslot: pointer to reserved slot
+ * @item: item to insert
*
- * Reserve a slot in a radix tree for the key @index.
+ * Insert an item into the radix tree at position @index.
*/
-int radix_tree_reserve(struct radix_tree_root *root, unsigned long index, void ***pslot)
+int radix_tree_insert(struct radix_tree_root *root,
+ unsigned long index, void *item)
{
- struct radix_tree_node *node = NULL, *tmp, **slot;
+ struct radix_tree_node *node = NULL, *slot;
unsigned int height, shift;
+ int offset;
int error;
+ BUG_ON(radix_tree_is_indirect_ptr(item));
+
/* Make sure the tree is high enough. */
if (index > radix_tree_maxindex(root->height)) {
error = radix_tree_extend(root, index);
if (error)
return error;
}
-
- slot = &root->rnode;
+
+ slot = indirect_to_ptr(root->rnode);
+
height = root->height;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+ offset = 0; /* uninitialised var warning */
while (height > 0) {
- if (*slot == NULL) {
+ if (slot == NULL) {
/* Have to add a child node. */
- if (!(tmp = radix_tree_node_alloc(root)))
+ if (!(slot = radix_tree_node_alloc(root)))
return -ENOMEM;
- *slot = tmp;
- if (node)
+ slot->height = height;
+ slot->parent = node;
+ if (node) {
+ rcu_assign_pointer(node->slots[offset], slot);
node->count++;
+ } else
+ rcu_assign_pointer(root->rnode, ptr_to_indirect(slot));
}
- /* Go a level down. */
- node = *slot;
- slot = (struct radix_tree_node **)
- (node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
+ /* Go a level down */
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ node = slot;
+ slot = node->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
- if (*slot != NULL)
+ if (slot != NULL)
return -EEXIST;
- if (node)
+
+ if (node) {
node->count++;
+ rcu_assign_pointer(node->slots[offset], item);
+ BUG_ON(tag_get(node, 0, offset));
+ BUG_ON(tag_get(node, 1, offset));
+ } else {
+ rcu_assign_pointer(root->rnode, item);
+ BUG_ON(root_tag_get(root, 0));
+ BUG_ON(root_tag_get(root, 1));
+ }
- *pslot = (void **)slot;
- **pslot = RADIX_TREE_SLOT_RESERVED;
return 0;
}
+EXPORT_SYMBOL(radix_tree_insert);
-EXPORT_SYMBOL(radix_tree_reserve);
+/*
+ * is_slot == 1 : search for the slot.
+ * is_slot == 0 : search for the node.
+ */
+static void *radix_tree_lookup_element(struct radix_tree_root *root,
+ unsigned long index, int is_slot)
+{
+ unsigned int height, shift;
+ struct radix_tree_node *node, **slot;
+
+ node = rcu_dereference_raw(root->rnode);
+ if (node == NULL)
+ return NULL;
+
+ if (!radix_tree_is_indirect_ptr(node)) {
+ if (index > 0)
+ return NULL;
+ return is_slot ? (void *)&root->rnode : node;
+ }
+ node = indirect_to_ptr(node);
+
+ height = node->height;
+ if (index > radix_tree_maxindex(height))
+ return NULL;
+
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+
+ do {
+ slot = (struct radix_tree_node **)
+ (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
+ node = rcu_dereference_raw(*slot);
+ if (node == NULL)
+ return NULL;
+
+ shift -= RADIX_TREE_MAP_SHIFT;
+ height--;
+ } while (height > 0);
+ return is_slot ? (void *)slot : indirect_to_ptr(node);
+}
/**
- * radix_tree_insert - insert into a radix tree
+ * radix_tree_lookup_slot - lookup a slot in a radix tree
* @root: radix tree root
* @index: index key
- * @item: item to insert
*
- * Insert an item into the radix tree at position @index.
+ * 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.
*/
-int radix_tree_insert(struct radix_tree_root *root, unsigned long index, void *item)
+void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
{
- void **slot;
- int error;
+ return (void **)radix_tree_lookup_element(root, index, 1);
+}
+EXPORT_SYMBOL(radix_tree_lookup_slot);
- error = radix_tree_reserve(root, index, &slot);
- if (!error)
- *slot = item;
- return error;
+/**
+ * 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.
+ *
+ * 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.
+ */
+void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+{
+ return radix_tree_lookup_element(root, index, 0);
}
+EXPORT_SYMBOL(radix_tree_lookup);
-EXPORT_SYMBOL(radix_tree_insert);
+/**
+ * radix_tree_tag_set - set a tag on a radix tree node
+ * @root: radix tree root
+ * @index: index key
+ * @tag: tag index
+ *
+ * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
+ * corresponding to @index in the radix tree. From
+ * 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,
+ unsigned long index, unsigned int tag)
+{
+ unsigned int height, shift;
+ struct radix_tree_node *slot;
+
+ height = root->height;
+ BUG_ON(index > radix_tree_maxindex(height));
+
+ slot = indirect_to_ptr(root->rnode);
+ shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+
+ while (height > 0) {
+ int offset;
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ if (!tag_get(slot, tag, offset))
+ tag_set(slot, tag, offset);
+ slot = slot->slots[offset];
+ BUG_ON(slot == NULL);
+ shift -= RADIX_TREE_MAP_SHIFT;
+ height--;
+ }
+
+ /* set the root's tag bit */
+ if (slot && !root_tag_get(root, tag))
+ root_tag_set(root, tag);
+
+ return slot;
+}
+EXPORT_SYMBOL(radix_tree_tag_set);
/**
- * radix_tree_lookup - perform lookup operation on a radix tree
+ * radix_tree_tag_clear - clear a tag on a radix tree node
* @root: radix tree root
* @index: index key
+ * @tag: tag index
*
- * Lookup them item at the position @index in the radix tree @root.
+ * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
+ * corresponding to @index in the radix tree. If
+ * 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_lookup(struct radix_tree_root *root, unsigned long index)
+void *radix_tree_tag_clear(struct radix_tree_root *root,
+ unsigned long index, unsigned int tag)
{
+ struct radix_tree_node *node = NULL;
+ struct radix_tree_node *slot = NULL;
unsigned int height, shift;
- struct radix_tree_node **slot;
+ int uninitialized_var(offset);
height = root->height;
if (index > radix_tree_maxindex(height))
- return NULL;
+ goto out;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- slot = &root->rnode;
+ shift = height * RADIX_TREE_MAP_SHIFT;
+ slot = indirect_to_ptr(root->rnode);
- while (height > 0) {
- if (*slot == NULL)
- return NULL;
+ while (shift) {
+ if (slot == NULL)
+ goto out;
- slot = (struct radix_tree_node **)
- ((*slot)->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
+ shift -= RADIX_TREE_MAP_SHIFT;
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ node = slot;
+ slot = slot->slots[offset];
+ }
+
+ if (slot == NULL)
+ goto out;
+
+ while (node) {
+ if (!tag_get(node, tag, offset))
+ goto out;
+ tag_clear(node, tag, offset);
+ if (any_tag_set(node, tag))
+ goto out;
+
+ index >>= RADIX_TREE_MAP_SHIFT;
+ offset = index & RADIX_TREE_MAP_MASK;
+ node = node->parent;
+ }
+
+ /* 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);
+
+/**
+ * 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
+ *
+ * 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.
+ */
+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;
+
+ /* check the root's tag bit */
+ if (!root_tag_get(root, tag))
+ return 0;
+
+ node = rcu_dereference_raw(root->rnode);
+ if (node == NULL)
+ return 0;
+
+ if (!radix_tree_is_indirect_ptr(node))
+ return (index == 0);
+ node = indirect_to_ptr(node);
+
+ 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;
+ if (!tag_get(node, tag, offset))
+ return 0;
+ if (height == 1)
+ return 1;
+ node = rcu_dereference_raw(node->slots[offset]);
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
+}
+EXPORT_SYMBOL(radix_tree_tag_get);
+
+/**
+ * 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;
+ unsigned long index, offset;
+
+ 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.
+ */
+ 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:
+ shift = (rnode->height - 1) * RADIX_TREE_MAP_SHIFT;
+ 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;
- return (void *) *slot;
+ 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_lookup);
+EXPORT_SYMBOL(radix_tree_next_chunk);
-static /* inline */ unsigned int
-__lookup(struct radix_tree_root *root, void **results, unsigned long index,
- unsigned int max_items, unsigned long *next_index,
- unsigned long max_index)
+/**
+ * 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.
+ *
+ * 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).
+ *
+ * The function returns number of leaves where the tag was set and sets
+ * *first_indexp to the first unscanned index.
+ * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
+ * be prepared to handle that.
+ */
+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)
{
- unsigned int nr_found = 0;
- unsigned int shift;
unsigned int height = root->height;
+ struct radix_tree_node *node = NULL;
struct radix_tree_node *slot;
+ unsigned int shift;
+ unsigned long tagged = 0;
+ unsigned long index = *first_indexp;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- slot = root->rnode;
+ 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;
+ }
- while (height > 0) {
- unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
- for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
- if (slot->slots[i] != NULL)
+ shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+ slot = indirect_to_ptr(root->rnode);
+
+ for (;;) {
+ unsigned long upindex;
+ int offset;
+
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ if (!slot->slots[offset])
+ goto next;
+ if (!tag_get(slot, iftag, offset))
+ goto next;
+ if (shift) {
+ /* Go down one level */
+ shift -= RADIX_TREE_MAP_SHIFT;
+ node = slot;
+ slot = slot->slots[offset];
+ continue;
+ }
+
+ /* tag the leaf */
+ tagged++;
+ tag_set(slot, settag, offset);
+
+ /* walk back up the path tagging interior nodes */
+ upindex = index;
+ while (node) {
+ upindex >>= RADIX_TREE_MAP_SHIFT;
+ offset = upindex & RADIX_TREE_MAP_MASK;
+
+ /* stop if we find a node with the tag already set */
+ if (tag_get(node, settag, offset))
break;
- index &= ~((1 << shift) - 1);
- index += 1 << shift;
+ tag_set(node, settag, offset);
+ node = node->parent;
}
- if (i == RADIX_TREE_MAP_SIZE)
- goto out;
- height--;
- shift -= RADIX_TREE_MAP_SHIFT;
- if (height == 0) {
- /* Bottom level: grab some items */
- unsigned long j;
-
- BUG_ON((shift + RADIX_TREE_MAP_SHIFT) != 0);
-
- j = index & RADIX_TREE_MAP_MASK;
- for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
- index++;
- if (slot->slots[j]) {
- results[nr_found++] = slot->slots[j];
- if (nr_found == max_items)
- goto out;
- }
- }
+
+ /*
+ * 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;
+
+next:
+ /* Go to next item at level determined by 'shift' */
+ index = ((index >> shift) + 1) << shift;
+ /* Overflow can happen when last_index is ~0UL... */
+ if (index > last_index || !index)
+ 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.
+ */
+ slot = slot->parent;
+ shift += RADIX_TREE_MAP_SHIFT;
}
- slot = slot->slots[i];
}
-out:
- *next_index = index;
- return nr_found;
-
+ /*
+ * 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.
+ */
+ if (tagged > 0)
+ root_tag_set(root, settag);
+ *first_indexp = index;
+
+ return tagged;
+}
+EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
+
+
+/**
+ * radix_tree_next_hole - find the next hole (not-present entry)
+ * @root: tree root
+ * @index: index key
+ * @max_scan: maximum range to search
+ *
+ * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
+ * indexed hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'return - index >= max_scan'
+ * will be true). In rare cases of index wrap-around, 0 will be returned.
+ *
+ * radix_tree_next_hole may be called under rcu_read_lock. However, like
+ * radix_tree_gang_lookup, this will not atomically search a snapshot of
+ * the tree at a single point in time. For example, if a hole is created
+ * at index 5, then subsequently a hole is created at index 10,
+ * radix_tree_next_hole covering both indexes may return 10 if called
+ * under rcu_read_lock.
+ */
+unsigned long radix_tree_next_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index))
+ break;
+ index++;
+ if (index == 0)
+ break;
+ }
+
+ return index;
}
+EXPORT_SYMBOL(radix_tree_next_hole);
+
+/**
+ * radix_tree_prev_hole - find the prev hole (not-present entry)
+ * @root: tree root
+ * @index: index key
+ * @max_scan: maximum range to search
+ *
+ * Search backwards in the range [max(index-max_scan+1, 0), index]
+ * for the first hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'index - return >= max_scan'
+ * will be true). In rare cases of wrap-around, ULONG_MAX will be returned.
+ *
+ * radix_tree_next_hole may be called under rcu_read_lock. However, like
+ * radix_tree_gang_lookup, this will not atomically search a snapshot of
+ * the tree at a single point in time. For example, if a hole is created
+ * at index 10, then subsequently a hole is created at index 5,
+ * radix_tree_prev_hole covering both indexes may return 5 if called under
+ * rcu_read_lock.
+ */
+unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index))
+ break;
+ index--;
+ if (index == ULONG_MAX)
+ break;
+ }
+
+ return index;
+}
+EXPORT_SYMBOL(radix_tree_prev_hole);
+
/**
* radix_tree_gang_lookup - perform multiple lookup on a radix tree
* @root: radix tree root
* *@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)
{
- const unsigned long max_index = radix_tree_maxindex(root->height);
- unsigned long cur_index = first_index;
+ struct radix_tree_iter iter;
+ void **slot;
unsigned int ret = 0;
- if (root->rnode == NULL)
- goto out;
- if (max_index == 0) { /* Bah. Special case */
- if (first_index == 0) {
- if (max_items > 0) {
- *results = root->rnode;
- ret = 1;
- }
- }
- goto out;
+ if (unlikely(!max_items))
+ return 0;
+
+ 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)
+ break;
}
- while (ret < max_items) {
- unsigned int nr_found;
- unsigned long next_index; /* Index of next search */
- if (cur_index > max_index)
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup);
+
+/**
+ * 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
+ * @indices: where their indices should be placed (but usually NULL)
+ * @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
+radix_tree_gang_lookup_slot(struct radix_tree_root *root,
+ void ***results, unsigned long *indices,
+ unsigned long first_index, unsigned int max_items)
+{
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
+
+ if (unlikely(!max_items))
+ return 0;
+
+ radix_tree_for_each_slot(slot, root, &iter, first_index) {
+ results[ret] = slot;
+ if (indices)
+ indices[ret] = iter.index;
+ if (++ret == max_items)
break;
- nr_found = __lookup(root, results + ret, cur_index,
- max_items - ret, &next_index, max_index);
- if (nr_found == 0) {
- if (!(cur_index & RADIX_TREE_MAP_MASK))
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
+
+/**
+ * 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_iter iter;
+ void **slot;
+ unsigned int ret = 0;
+
+ if (unlikely(!max_items))
+ return 0;
+
+ 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)
+ break;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
+
+/**
+ * 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)
+{
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
+
+ if (unlikely(!max_items))
+ return 0;
+
+ radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
+ results[ret] = slot;
+ if (++ret == max_items)
+ break;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
+
+#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;
+
+ height = slot->height;
+ 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;
- /*
- * It could be that there simply were no items to the
- * right of `cur_index' in the leaf node. So we still
- * need to search for additional nodes to the right of
- * this one.
- */
+ index &= ~((1UL << shift) - 1);
+ index += 1UL << shift;
+ if (index == 0)
+ goto out; /* 32-bit wraparound */
+ i++;
+ if (i == RADIX_TREE_MAP_SIZE)
+ goto out;
}
- ret += nr_found;
- cur_index = next_index;
+
+ 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 ret;
+ 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);
+ max_index = radix_tree_maxindex(node->height);
+ if (cur_index > max_index)
+ break;
+
+ 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 */
+
+/**
+ * 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) {
+ struct radix_tree_node *to_free = root->rnode;
+ struct radix_tree_node *slot;
+
+ BUG_ON(!radix_tree_is_indirect_ptr(to_free));
+ to_free = indirect_to_ptr(to_free);
+
+ /*
+ * 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;
+
+ /*
+ * 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) as far as dependent read barriers go.
+ */
+ slot = to_free->slots[0];
+ if (root->height > 1) {
+ slot->parent = NULL;
+ slot = ptr_to_indirect(slot);
+ }
+ root->rnode = slot;
+ root->height--;
+
+ /*
+ * 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;
+
+ radix_tree_node_free(to_free);
+ }
}
-EXPORT_SYMBOL(radix_tree_gang_lookup);
/**
* radix_tree_delete - delete an item from a radix tree
* @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.
*/
-int radix_tree_delete(struct radix_tree_root *root, unsigned long index)
+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 *node = NULL;
+ struct radix_tree_node *slot = NULL;
+ struct radix_tree_node *to_free;
unsigned int height, shift;
+ int tag;
+ int uninitialized_var(offset);
height = root->height;
if (index > radix_tree_maxindex(height))
- return -ENOENT;
+ goto out;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
- pathp->node = NULL;
- pathp->slot = &root->rnode;
+ slot = root->rnode;
+ if (height == 0) {
+ root_tag_clear_all(root);
+ root->rnode = NULL;
+ goto out;
+ }
+ slot = indirect_to_ptr(slot);
+ shift = height * RADIX_TREE_MAP_SHIFT;
- while (height > 0) {
- if (*pathp->slot == NULL)
- return -ENOENT;
+ do {
+ if (slot == NULL)
+ goto out;
- pathp[1].node = *pathp[0].slot;
- pathp[1].slot = (struct radix_tree_node **)
- (pathp[1].node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
- pathp++;
shift -= RADIX_TREE_MAP_SHIFT;
- height--;
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ node = slot;
+ slot = slot->slots[offset];
+ } while (shift);
+
+ if (slot == NULL)
+ goto out;
+
+ /*
+ * Clear all tags associated with the item to be deleted.
+ * This way of doing it would be inefficient, but seldom is any set.
+ */
+ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+ if (tag_get(node, tag, offset))
+ radix_tree_tag_clear(root, index, tag);
}
- if (*pathp[0].slot == NULL)
- return -ENOENT;
+ to_free = NULL;
+ /* Now free the nodes we do not need anymore */
+ while (node) {
+ node->slots[offset] = NULL;
+ 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);
- *pathp[0].slot = NULL;
- while (pathp[0].node && --pathp[0].node->count == 0) {
- pathp--;
- *pathp[0].slot = NULL;
- radix_tree_node_free(pathp[1].node);
+ if (node->count) {
+ if (node == indirect_to_ptr(root->rnode))
+ radix_tree_shrink(root);
+ goto out;
+ }
+
+ /* Node with zero slots in use so free it */
+ to_free = node;
+
+ index >>= RADIX_TREE_MAP_SHIFT;
+ offset = index & RADIX_TREE_MAP_MASK;
+ node = node->parent;
}
- return 0;
-}
+ 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);
-static void radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags)
+/**
+ * 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)
{
memset(node, 0, sizeof(struct radix_tree_node));
}
-static void *radix_tree_node_pool_alloc(int gfp_mask, void *data)
+static __init unsigned long __maxindex(unsigned int height)
{
- return kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
+ 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;
}
-static void radix_tree_node_pool_free(void *node, void *data)
+static __init void radix_tree_init_maxindex(void)
{
- kmem_cache_free(radix_tree_node_cachep, node);
+ 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;
}
-/*
- * FIXME! 512 nodes is 200-300k of memory. This needs to be
- * scaled by the amount of available memory, and hopefully
- * reduced also.
- */
void __init radix_tree_init(void)
{
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
- SLAB_HWCACHE_ALIGN, radix_tree_node_ctor, NULL);
- if (!radix_tree_node_cachep)
- panic ("Failed to create radix_tree_node cache\n");
- radix_tree_node_pool = mempool_create(512, radix_tree_node_pool_alloc,
- radix_tree_node_pool_free, NULL);
- if (!radix_tree_node_pool)
- panic ("Failed to create radix_tree_node pool\n");
+ SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
+ radix_tree_node_ctor);
+ radix_tree_init_maxindex();
+ hotcpu_notifier(radix_tree_callback, 0);
}
projects / linux-flexiantxendom0-3.2.10.git / blobdiff