* 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
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.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/gfp.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/rcupdate.h>
struct radix_tree_node {
unsigned int height; /* Height from the bottom */
unsigned int count;
- struct rcu_head rcu_head;
- void *slots[RADIX_TREE_MAP_SIZE];
+ 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];
};
-struct radix_tree_path {
- struct radix_tree_node *node;
- int offset;
-};
-
#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
};
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;
}
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;
+}
+
/*
* This assumes that the caller has performed appropriate preallocation, and
* that the caller has pinned this thread of control to the current CPU.
{
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.
*/
- tag_clear(node, 0, 0);
- tag_clear(node, 1, 0);
+ for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
+ tag_clear(node, i, 0);
+
node->slots[0] = NULL;
node->count = 0;
* 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)
{
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;
if (!(node = radix_tree_node_alloc(root)))
return -ENOMEM;
- /* Increase the height. */
- node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
-
/* 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 = radix_tree_ptr_to_indirect(node);
+ 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);
return error;
}
- slot = radix_tree_indirect_to_ptr(root->rnode);
+ slot = indirect_to_ptr(root->rnode);
height = root->height;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
if (!(slot = radix_tree_node_alloc(root)))
return -ENOMEM;
slot->height = height;
+ slot->parent = node;
if (node) {
rcu_assign_pointer(node->slots[offset], slot);
node->count++;
} else
- rcu_assign_pointer(root->rnode,
- radix_tree_ptr_to_indirect(slot));
+ rcu_assign_pointer(root->rnode, ptr_to_indirect(slot));
}
/* Go a level down */
unsigned int height, shift;
struct radix_tree_node *node, **slot;
- node = rcu_dereference(root->rnode);
+ node = rcu_dereference_raw(root->rnode);
if (node == NULL)
return NULL;
return NULL;
return is_slot ? (void *)&root->rnode : node;
}
- node = radix_tree_indirect_to_ptr(node);
+ node = indirect_to_ptr(node);
height = node->height;
if (index > radix_tree_maxindex(height))
do {
slot = (struct radix_tree_node **)
(node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
- node = rcu_dereference(*slot);
+ node = rcu_dereference_raw(*slot);
if (node == NULL)
return NULL;
height--;
} while (height > 0);
- return is_slot ? (void *)slot:node;
+ return is_slot ? (void *)slot : indirect_to_ptr(node);
}
/**
height = root->height;
BUG_ON(index > radix_tree_maxindex(height));
- slot = radix_tree_indirect_to_ptr(root->rnode);
+ slot = indirect_to_ptr(root->rnode);
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
while (height > 0) {
void *radix_tree_tag_clear(struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
- /*
- * The radix tree path needs to be one longer than the maximum path
- * since the "list" is null terminated.
- */
- struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
+ struct radix_tree_node *node = NULL;
struct radix_tree_node *slot = NULL;
unsigned int height, shift;
+ int uninitialized_var(offset);
height = root->height;
if (index > radix_tree_maxindex(height))
goto out;
- shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- pathp->node = NULL;
- slot = radix_tree_indirect_to_ptr(root->rnode);
-
- while (height > 0) {
- int offset;
+ shift = height * RADIX_TREE_MAP_SHIFT;
+ slot = indirect_to_ptr(root->rnode);
+ while (shift) {
if (slot == NULL)
goto out;
+ shift -= RADIX_TREE_MAP_SHIFT;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- pathp[1].offset = offset;
- pathp[1].node = slot;
+ node = slot;
slot = slot->slots[offset];
- pathp++;
- shift -= RADIX_TREE_MAP_SHIFT;
- height--;
}
if (slot == NULL)
goto out;
- while (pathp->node) {
- if (!tag_get(pathp->node, tag, pathp->offset))
+ while (node) {
+ if (!tag_get(node, tag, offset))
goto out;
- tag_clear(pathp->node, tag, pathp->offset);
- if (any_tag_set(pathp->node, tag))
+ tag_clear(node, tag, offset);
+ if (any_tag_set(node, tag))
goto out;
- pathp--;
+
+ index >>= RADIX_TREE_MAP_SHIFT;
+ offset = index & RADIX_TREE_MAP_MASK;
+ node = node->parent;
}
/* clear the root's tag bit */
}
EXPORT_SYMBOL(radix_tree_tag_clear);
-#ifndef __KERNEL__ /* Only the test harness uses this at present */
/**
* radix_tree_tag_get - get a tag on a radix tree node
* @root: radix tree root
*
* 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;
- int saw_unset_tag = 0;
/* check the root's tag bit */
if (!root_tag_get(root, tag))
return 0;
- node = rcu_dereference(root->rnode);
+ node = rcu_dereference_raw(root->rnode);
if (node == NULL)
return 0;
if (!radix_tree_is_indirect_ptr(node))
return (index == 0);
- node = radix_tree_indirect_to_ptr(node);
+ node = indirect_to_ptr(node);
height = node->height;
if (index > radix_tree_maxindex(height))
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;
+
+ 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);
+
+/**
+ * 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 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;
+
+ 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;
+ 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;
+ tag_set(node, settag, offset);
+ node = node->parent;
+ }
/*
- * This is just a debug check. Later, we can bale as soon as
- * we see an unset tag.
+ * 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.
*/
- if (!tag_get(node, tag, offset))
- saw_unset_tag = 1;
- if (height == 1) {
- int ret = tag_get(node, tag, offset);
+ node = NULL;
- BUG_ON(ret && saw_unset_tag);
- return !!ret;
+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;
}
- node = rcu_dereference(node->slots[offset]);
- shift -= RADIX_TREE_MAP_SHIFT;
- height--;
}
+ /*
+ * 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_tag_get);
-#endif
+EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
+
/**
* radix_tree_next_hole - find the next hole (not-present entry)
*
* 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, LONG_MAX will be returned.
+ * 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
if (!radix_tree_lookup(root, index))
break;
index--;
- if (index == LONG_MAX)
+ if (index == ULONG_MAX)
break;
}
}
EXPORT_SYMBOL(radix_tree_prev_hole);
-static unsigned int
-__lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
- unsigned int max_items, unsigned long *next_index)
-{
- unsigned int nr_found = 0;
- unsigned int shift, height;
- unsigned long i;
-
- height = slot->height;
- if (height == 0)
- goto out;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
- for ( ; height > 1; height--) {
- i = (index >> shift) & RADIX_TREE_MAP_MASK;
- for (;;) {
- if (slot->slots[i] != NULL)
- break;
- index &= ~((1UL << shift) - 1);
- index += 1UL << shift;
- if (index == 0)
- goto out; /* 32-bit wraparound */
- i++;
- if (i == RADIX_TREE_MAP_SIZE)
- goto out;
- }
-
- shift -= RADIX_TREE_MAP_SHIFT;
- slot = rcu_dereference(slot->slots[i]);
- if (slot == NULL)
- goto out;
- }
-
- /* Bottom level: grab some items */
- for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
- index++;
- if (slot->slots[i]) {
- results[nr_found++] = &(slot->slots[i]);
- if (nr_found == max_items)
- goto out;
- }
- }
-out:
- *next_index = index;
- return nr_found;
-}
-
/**
* radix_tree_gang_lookup - perform multiple lookup on a radix tree
* @root: radix tree root
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items)
{
- unsigned long max_index;
- struct radix_tree_node *node;
- unsigned long cur_index = first_index;
- unsigned int ret;
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
- node = rcu_dereference(root->rnode);
- if (!node)
+ if (unlikely(!max_items))
return 0;
- if (!radix_tree_is_indirect_ptr(node)) {
- if (first_index > 0)
- return 0;
- results[0] = node;
- return 1;
- }
- node = radix_tree_indirect_to_ptr(node);
-
- max_index = radix_tree_maxindex(node->height);
-
- ret = 0;
- while (ret < max_items) {
- unsigned int nr_found, slots_found, i;
- unsigned long next_index; /* Index of next search */
-
- if (cur_index > max_index)
- break;
- slots_found = __lookup(node, (void ***)results + ret, cur_index,
- max_items - ret, &next_index);
- nr_found = 0;
- for (i = 0; i < slots_found; i++) {
- struct radix_tree_node *slot;
- slot = *(((void ***)results)[ret + i]);
- if (!slot)
- continue;
- results[ret + nr_found] = rcu_dereference(slot);
- nr_found++;
- }
- ret += nr_found;
- if (next_index == 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;
- cur_index = next_index;
}
return ret;
* 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
*
* protection, radix_tree_deref_slot may fail requiring a retry.
*/
unsigned int
-radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
+radix_tree_gang_lookup_slot(struct radix_tree_root *root,
+ void ***results, unsigned long *indices,
unsigned long first_index, unsigned int max_items)
{
- unsigned long max_index;
- struct radix_tree_node *node;
- unsigned long cur_index = first_index;
- unsigned int ret;
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
- node = rcu_dereference(root->rnode);
- if (!node)
+ if (unlikely(!max_items))
return 0;
- if (!radix_tree_is_indirect_ptr(node)) {
- if (first_index > 0)
- return 0;
- results[0] = (void **)&root->rnode;
- return 1;
- }
- node = radix_tree_indirect_to_ptr(node);
-
- max_index = radix_tree_maxindex(node->height);
-
- ret = 0;
- while (ret < max_items) {
- unsigned int slots_found;
- unsigned long next_index; /* Index of next search */
-
- if (cur_index > max_index)
- break;
- slots_found = __lookup(node, results + ret, cur_index,
- max_items - ret, &next_index);
- ret += slots_found;
- if (next_index == 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;
- cur_index = next_index;
}
return ret;
}
EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
-/*
- * FIXME: the two tag_get()s here should use find_next_bit() instead of
- * open-coding the search.
- */
-static unsigned int
-__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
- unsigned int max_items, unsigned long *next_index, unsigned int tag)
-{
- unsigned int nr_found = 0;
- unsigned int shift, height;
-
- height = slot->height;
- if (height == 0)
- goto out;
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
- while (height > 0) {
- unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
-
- for (;;) {
- if (tag_get(slot, tag, i))
- break;
- index &= ~((1UL << shift) - 1);
- index += 1UL << shift;
- if (index == 0)
- goto out; /* 32-bit wraparound */
- i++;
- if (i == RADIX_TREE_MAP_SIZE)
- goto out;
- }
- height--;
- if (height == 0) { /* Bottom level: grab some items */
- unsigned long j = index & RADIX_TREE_MAP_MASK;
-
- for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
- index++;
- if (!tag_get(slot, tag, j))
- continue;
- /*
- * Even though the tag was found set, we need to
- * recheck that we have a non-NULL node, because
- * if this lookup is lockless, it may have been
- * subsequently deleted.
- *
- * Similar care must be taken in any place that
- * lookup ->slots[x] without a lock (ie. can't
- * rely on its value remaining the same).
- */
- if (slot->slots[j]) {
- results[nr_found++] = &(slot->slots[j]);
- if (nr_found == max_items)
- goto out;
- }
- }
- }
- shift -= RADIX_TREE_MAP_SHIFT;
- slot = rcu_dereference(slot->slots[i]);
- if (slot == NULL)
- break;
- }
-out:
- *next_index = index;
- return nr_found;
-}
-
/**
* radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
* based on a tag
unsigned long first_index, unsigned int max_items,
unsigned int tag)
{
- struct radix_tree_node *node;
- unsigned long max_index;
- unsigned long cur_index = first_index;
- unsigned int ret;
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
- /* check the root's tag bit */
- if (!root_tag_get(root, tag))
+ if (unlikely(!max_items))
return 0;
- node = rcu_dereference(root->rnode);
- if (!node)
- return 0;
-
- if (!radix_tree_is_indirect_ptr(node)) {
- if (first_index > 0)
- return 0;
- results[0] = node;
- return 1;
- }
- node = radix_tree_indirect_to_ptr(node);
-
- max_index = radix_tree_maxindex(node->height);
-
- ret = 0;
- while (ret < max_items) {
- unsigned int nr_found, slots_found, i;
- unsigned long next_index; /* Index of next search */
-
- if (cur_index > max_index)
+ 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;
- slots_found = __lookup_tag(node, (void ***)results + ret,
- cur_index, max_items - ret, &next_index, tag);
- nr_found = 0;
- for (i = 0; i < slots_found; i++) {
- struct radix_tree_node *slot;
- slot = *(((void ***)results)[ret + i]);
- if (!slot)
- continue;
- results[ret + nr_found] = rcu_dereference(slot);
- nr_found++;
- }
- ret += nr_found;
- if (next_index == 0)
- break;
- cur_index = next_index;
}
return ret;
unsigned long first_index, unsigned int max_items,
unsigned int tag)
{
- struct radix_tree_node *node;
- unsigned long max_index;
- unsigned long cur_index = first_index;
- unsigned int ret;
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int ret = 0;
- /* check the root's tag bit */
- if (!root_tag_get(root, tag))
+ if (unlikely(!max_items))
return 0;
- node = rcu_dereference(root->rnode);
- if (!node)
- return 0;
+ radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
+ results[ret] = slot;
+ if (++ret == max_items)
+ break;
+ }
- if (!radix_tree_is_indirect_ptr(node)) {
- if (first_index > 0)
- return 0;
- results[0] = (void **)&root->rnode;
- return 1;
+ 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;
+ 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;
}
- node = radix_tree_indirect_to_ptr(node);
- max_index = radix_tree_maxindex(node->height);
+ /* 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;
+}
- ret = 0;
- while (ret < max_items) {
- unsigned int slots_found;
- unsigned long next_index; /* Index of next search */
+/**
+ * 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;
- if (cur_index > max_index)
+ 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;
- slots_found = __lookup_tag(node, results + ret,
- cur_index, max_items - ret, &next_index, tag);
- ret += slots_found;
- if (next_index == 0)
+ }
+
+ node = indirect_to_ptr(node);
+ max_index = radix_tree_maxindex(node->height);
+ if (cur_index > max_index)
break;
- cur_index = next_index;
- }
- return ret;
-}
-EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
+ 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
/* try to shrink tree height */
while (root->height > 0) {
struct radix_tree_node *to_free = root->rnode;
- void *newptr;
+ struct radix_tree_node *slot;
BUG_ON(!radix_tree_is_indirect_ptr(to_free));
- to_free = radix_tree_indirect_to_ptr(to_free);
+ to_free = indirect_to_ptr(to_free);
/*
* The candidate node has more than one child, or its child
/*
* 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
+ * 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).
+ * one (root->rnode) as far as dependent read barriers go.
*/
- newptr = to_free->slots[0];
- if (root->height > 1)
- newptr = radix_tree_ptr_to_indirect(newptr);
- root->rnode = newptr;
+ 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);
}
}
*/
void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
{
- /*
- * The radix tree path needs to be one longer than the maximum path
- * since the "list" is null terminated.
- */
- struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *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 offset;
+ int uninitialized_var(offset);
height = root->height;
if (index > radix_tree_maxindex(height))
root->rnode = NULL;
goto out;
}
- slot = radix_tree_indirect_to_ptr(slot);
-
- shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
- pathp->node = NULL;
+ slot = indirect_to_ptr(slot);
+ shift = height * RADIX_TREE_MAP_SHIFT;
do {
if (slot == NULL)
goto out;
- pathp++;
+ shift -= RADIX_TREE_MAP_SHIFT;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- pathp->offset = offset;
- pathp->node = slot;
+ node = slot;
slot = slot->slots[offset];
- shift -= RADIX_TREE_MAP_SHIFT;
- height--;
- } while (height > 0);
+ } while (shift);
if (slot == NULL)
goto out;
/*
- * Clear all tags associated with the just-deleted item
+ * 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(pathp->node, tag, pathp->offset))
+ if (tag_get(node, tag, offset))
radix_tree_tag_clear(root, index, tag);
}
to_free = NULL;
/* Now free the nodes we do not need anymore */
- while (pathp->node) {
- pathp->node->slots[pathp->offset] = NULL;
- pathp->node->count--;
+ 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);
- if (pathp->node->count) {
- if (pathp->node ==
- radix_tree_indirect_to_ptr(root->rnode))
+ 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 = pathp->node;
- pathp--;
+ to_free = node;
+ index >>= RADIX_TREE_MAP_SHIFT;
+ offset = index & RADIX_TREE_MAP_MASK;
+ node = node->parent;
}
+
root_tag_clear_all(root);
root->height = 0;
root->rnode = NULL;
Code Review / linux-3.10.git / blobdiff