mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 13:30:57 +07:00
e504f3fdd6
We have already acknowledged that swapoff of a tmpfs file is slower than it was before conversion to the generic radix_tree: a little slower there will be acceptable, if the hotter paths are faster. But it was a shock to find swapoff of a 500MB file 20 times slower on my laptop, taking 10 minutes; and at that rate it significantly slows down my testing. Now, most of that turned out to be overhead from PROVE_LOCKING and PROVE_RCU: without those it was only 4 times slower than before; and more realistic tests on other machines don't fare as badly. I've tried a number of things to improve it, including tagging the swap entries, then doing lookup by tag: I'd expected that to halve the time, but in practice it's erratic, and often counter-productive. The only change I've so far found to make a consistent improvement, is to short-circuit the way we go back and forth, gang lookup packing entries into the array supplied, then shmem scanning that array for the target entry. Scanning in place doubles the speed, so it's now only twice as slow as before (or three times slower when the PROVEs are on). So, add radix_tree_locate_item() as an expedient, once-off, single-caller hack to do the lookup directly in place. #ifdef it on CONFIG_SHMEM and CONFIG_SWAP, as much to document its limited applicability as save space in other configurations. And, sadly, #include sched.h for cond_resched(). Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1522 lines
40 KiB
C
1522 lines
40 KiB
C
/*
|
|
* Copyright (C) 2001 Momchil Velikov
|
|
* Portions Copyright (C) 2001 Christoph Hellwig
|
|
* Copyright (C) 2005 SGI, Christoph Lameter
|
|
* Copyright (C) 2006 Nick Piggin
|
|
*
|
|
* 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/module.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>
|
|
|
|
|
|
#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;
|
|
struct rcu_head rcu_head;
|
|
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))
|
|
|
|
/*
|
|
* 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 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;
|
|
}
|
|
/*
|
|
* 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)
|
|
{
|
|
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)
|
|
{
|
|
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)
|
|
{
|
|
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;
|
|
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 {
|
|
unsigned int newheight;
|
|
if (!(node = radix_tree_node_alloc(root)))
|
|
return -ENOMEM;
|
|
|
|
/* Increase the height. */
|
|
node->slots[0] = 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);
|
|
}
|
|
|
|
newheight = root->height+1;
|
|
node->height = newheight;
|
|
node->count = 1;
|
|
node = ptr_to_indirect(node);
|
|
rcu_assign_pointer(root->rnode, node);
|
|
root->height = newheight;
|
|
} while (height > root->height);
|
|
out:
|
|
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 = 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 = 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) {
|
|
/* Have to add a child node. */
|
|
if (!(slot = radix_tree_node_alloc(root)))
|
|
return -ENOMEM;
|
|
slot->height = height;
|
|
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 */
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
node = slot;
|
|
slot = node->slots[offset];
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
height--;
|
|
}
|
|
|
|
if (slot != NULL)
|
|
return -EEXIST;
|
|
|
|
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));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_insert);
|
|
|
|
/*
|
|
* 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_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)
|
|
{
|
|
return (void **)radix_tree_lookup_element(root, index, 1);
|
|
}
|
|
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.
|
|
*
|
|
* 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);
|
|
|
|
/**
|
|
* 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_tag_clear - clear a tag on a radix tree node
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @tag: tag index
|
|
*
|
|
* 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_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 *slot = NULL;
|
|
unsigned int height, shift;
|
|
|
|
height = root->height;
|
|
if (index > radix_tree_maxindex(height))
|
|
goto out;
|
|
|
|
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
|
pathp->node = NULL;
|
|
slot = indirect_to_ptr(root->rnode);
|
|
|
|
while (height > 0) {
|
|
int offset;
|
|
|
|
if (slot == NULL)
|
|
goto out;
|
|
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
pathp[1].offset = offset;
|
|
pathp[1].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))
|
|
goto out;
|
|
tag_clear(pathp->node, tag, pathp->offset);
|
|
if (any_tag_set(pathp->node, tag))
|
|
goto out;
|
|
pathp--;
|
|
}
|
|
|
|
/* clear the root's tag bit */
|
|
if (root_tag_get(root, tag))
|
|
root_tag_clear(root, tag);
|
|
|
|
out:
|
|
return slot;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_clear);
|
|
|
|
/**
|
|
* 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;
|
|
int saw_unset_tag = 0;
|
|
|
|
/* 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;
|
|
|
|
/*
|
|
* This is just a debug check. Later, we can bale as soon as
|
|
* we see an unset tag.
|
|
*/
|
|
if (!tag_get(node, tag, offset))
|
|
saw_unset_tag = 1;
|
|
if (height == 1)
|
|
return !!tag_get(node, tag, offset);
|
|
node = rcu_dereference_raw(node->slots[offset]);
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
height--;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_get);
|
|
|
|
/**
|
|
* 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_path path[height];
|
|
struct radix_tree_path *pathp = path;
|
|
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);
|
|
|
|
/*
|
|
* we fill the path from (root->height - 2) to 0, leaving the index at
|
|
* (root->height - 1) as a terminator. Zero the node in the terminator
|
|
* so that we can use this to end walk loops back up the path.
|
|
*/
|
|
path[height - 1].node = NULL;
|
|
|
|
for (;;) {
|
|
int offset;
|
|
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
if (!slot->slots[offset])
|
|
goto next;
|
|
if (!tag_get(slot, iftag, offset))
|
|
goto next;
|
|
if (height > 1) {
|
|
/* Go down one level */
|
|
height--;
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
path[height - 1].node = slot;
|
|
path[height - 1].offset = offset;
|
|
slot = slot->slots[offset];
|
|
continue;
|
|
}
|
|
|
|
/* tag the leaf */
|
|
tagged++;
|
|
tag_set(slot, settag, offset);
|
|
|
|
/* walk back up the path tagging interior nodes */
|
|
pathp = &path[0];
|
|
while (pathp->node) {
|
|
/* stop if we find a node with the tag already set */
|
|
if (tag_get(pathp->node, settag, pathp->offset))
|
|
break;
|
|
tag_set(pathp->node, settag, pathp->offset);
|
|
pathp++;
|
|
}
|
|
|
|
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 = path[height - 1].node;
|
|
height++;
|
|
shift += RADIX_TREE_MAP_SHIFT;
|
|
}
|
|
}
|
|
/*
|
|
* 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);
|
|
|
|
static unsigned int
|
|
__lookup(struct radix_tree_node *slot, void ***results, unsigned long *indices,
|
|
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_raw(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++) {
|
|
if (slot->slots[i]) {
|
|
results[nr_found] = &(slot->slots[i]);
|
|
if (indices)
|
|
indices[nr_found] = index;
|
|
if (++nr_found == max_items) {
|
|
index++;
|
|
goto out;
|
|
}
|
|
}
|
|
index++;
|
|
}
|
|
out:
|
|
*next_index = index;
|
|
return nr_found;
|
|
}
|
|
|
|
/**
|
|
* radix_tree_gang_lookup - perform multiple lookup on a radix tree
|
|
* @root: radix tree root
|
|
* @results: where the results of the lookup are placed
|
|
* @first_index: start the lookup from this key
|
|
* @max_items: place up to this many items at *results
|
|
*
|
|
* Performs an index-ascending scan of the tree for present items. Places
|
|
* them at *@results and returns the number of items which were placed at
|
|
* *@results.
|
|
*
|
|
* The implementation is naive.
|
|
*
|
|
* Like radix_tree_lookup, radix_tree_gang_lookup may be called under
|
|
* rcu_read_lock. In this case, rather than the returned results being
|
|
* an atomic snapshot of the tree at a single point in time, the semantics
|
|
* of an RCU protected gang lookup are as though multiple radix_tree_lookups
|
|
* have been issued in individual locks, and results stored in 'results'.
|
|
*/
|
|
unsigned int
|
|
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
|
|
unsigned long first_index, unsigned int max_items)
|
|
{
|
|
unsigned long max_index;
|
|
struct radix_tree_node *node;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
node = rcu_dereference_raw(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 = 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, NULL,
|
|
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] =
|
|
indirect_to_ptr(rcu_dereference_raw(slot));
|
|
nr_found++;
|
|
}
|
|
ret += nr_found;
|
|
if (next_index == 0)
|
|
break;
|
|
cur_index = next_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)
|
|
{
|
|
unsigned long max_index;
|
|
struct radix_tree_node *node;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
node = rcu_dereference_raw(root->rnode);
|
|
if (!node)
|
|
return 0;
|
|
|
|
if (!radix_tree_is_indirect_ptr(node)) {
|
|
if (first_index > 0)
|
|
return 0;
|
|
results[0] = (void **)&root->rnode;
|
|
if (indices)
|
|
indices[0] = 0;
|
|
return 1;
|
|
}
|
|
node = 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,
|
|
indices ? indices + ret : NULL,
|
|
cur_index, max_items - ret, &next_index);
|
|
ret += slots_found;
|
|
if (next_index == 0)
|
|
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_raw(slot->slots[i]);
|
|
if (slot == NULL)
|
|
break;
|
|
}
|
|
out:
|
|
*next_index = index;
|
|
return nr_found;
|
|
}
|
|
|
|
/**
|
|
* radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
|
|
* based on a tag
|
|
* @root: radix tree root
|
|
* @results: where the results of the lookup are placed
|
|
* @first_index: start the lookup from this key
|
|
* @max_items: place up to this many items at *results
|
|
* @tag: the tag index (< RADIX_TREE_MAX_TAGS)
|
|
*
|
|
* Performs an index-ascending scan of the tree for present items which
|
|
* have the tag indexed by @tag set. Places the items at *@results and
|
|
* returns the number of items which were placed at *@results.
|
|
*/
|
|
unsigned int
|
|
radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
|
|
unsigned long first_index, unsigned int max_items,
|
|
unsigned int tag)
|
|
{
|
|
struct radix_tree_node *node;
|
|
unsigned long max_index;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
/* check the root's tag bit */
|
|
if (!root_tag_get(root, tag))
|
|
return 0;
|
|
|
|
node = rcu_dereference_raw(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 = 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_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] =
|
|
indirect_to_ptr(rcu_dereference_raw(slot));
|
|
nr_found++;
|
|
}
|
|
ret += nr_found;
|
|
if (next_index == 0)
|
|
break;
|
|
cur_index = next_index;
|
|
}
|
|
|
|
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_node *node;
|
|
unsigned long max_index;
|
|
unsigned long cur_index = first_index;
|
|
unsigned int ret;
|
|
|
|
/* check the root's tag bit */
|
|
if (!root_tag_get(root, tag))
|
|
return 0;
|
|
|
|
node = rcu_dereference_raw(root->rnode);
|
|
if (!node)
|
|
return 0;
|
|
|
|
if (!radix_tree_is_indirect_ptr(node)) {
|
|
if (first_index > 0)
|
|
return 0;
|
|
results[0] = (void **)&root->rnode;
|
|
return 1;
|
|
}
|
|
node = 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_tag(node, results + ret,
|
|
cur_index, max_items - ret, &next_index, tag);
|
|
ret += slots_found;
|
|
if (next_index == 0)
|
|
break;
|
|
cur_index = next_index;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/* 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);
|
|
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;
|
|
void *newptr;
|
|
|
|
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.
|
|
*/
|
|
newptr = to_free->slots[0];
|
|
if (root->height > 1)
|
|
newptr = ptr_to_indirect(newptr);
|
|
root->rnode = newptr;
|
|
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);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
/*
|
|
* 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 *slot = NULL;
|
|
struct radix_tree_node *to_free;
|
|
unsigned int height, shift;
|
|
int tag;
|
|
int offset;
|
|
|
|
height = root->height;
|
|
if (index > radix_tree_maxindex(height))
|
|
goto out;
|
|
|
|
slot = root->rnode;
|
|
if (height == 0) {
|
|
root_tag_clear_all(root);
|
|
root->rnode = NULL;
|
|
goto out;
|
|
}
|
|
slot = indirect_to_ptr(slot);
|
|
|
|
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
|
pathp->node = NULL;
|
|
|
|
do {
|
|
if (slot == NULL)
|
|
goto out;
|
|
|
|
pathp++;
|
|
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
pathp->offset = offset;
|
|
pathp->node = slot;
|
|
slot = slot->slots[offset];
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
height--;
|
|
} while (height > 0);
|
|
|
|
if (slot == NULL)
|
|
goto out;
|
|
|
|
/*
|
|
* Clear all tags associated with the just-deleted item
|
|
*/
|
|
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
|
if (tag_get(pathp->node, tag, pathp->offset))
|
|
radix_tree_tag_clear(root, index, tag);
|
|
}
|
|
|
|
to_free = NULL;
|
|
/* Now free the nodes we do not need anymore */
|
|
while (pathp->node) {
|
|
pathp->node->slots[pathp->offset] = NULL;
|
|
pathp->node->count--;
|
|
/*
|
|
* Queue the node for deferred freeing after the
|
|
* last reference to it disappears (set NULL, above).
|
|
*/
|
|
if (to_free)
|
|
radix_tree_node_free(to_free);
|
|
|
|
if (pathp->node->count) {
|
|
if (pathp->node == 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--;
|
|
|
|
}
|
|
root_tag_clear_all(root);
|
|
root->height = 0;
|
|
root->rnode = NULL;
|
|
if (to_free)
|
|
radix_tree_node_free(to_free);
|
|
|
|
out:
|
|
return slot;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_delete);
|
|
|
|
/**
|
|
* radix_tree_tagged - test whether any items in the tree are tagged
|
|
* @root: radix tree root
|
|
* @tag: tag to test
|
|
*/
|
|
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
|
|
{
|
|
return root_tag_get(root, tag);
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tagged);
|
|
|
|
static void
|
|
radix_tree_node_ctor(void *node)
|
|
{
|
|
memset(node, 0, sizeof(struct radix_tree_node));
|
|
}
|
|
|
|
static __init unsigned long __maxindex(unsigned int height)
|
|
{
|
|
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 __init void radix_tree_init_maxindex(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
|
|
height_to_maxindex[i] = __maxindex(i);
|
|
}
|
|
|
|
static int radix_tree_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
int cpu = (long)hcpu;
|
|
struct radix_tree_preload *rtp;
|
|
|
|
/* Free per-cpu pool of perloaded nodes */
|
|
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
|
|
rtp = &per_cpu(radix_tree_preloads, cpu);
|
|
while (rtp->nr) {
|
|
kmem_cache_free(radix_tree_node_cachep,
|
|
rtp->nodes[rtp->nr-1]);
|
|
rtp->nodes[rtp->nr-1] = NULL;
|
|
rtp->nr--;
|
|
}
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
void __init radix_tree_init(void)
|
|
{
|
|
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
|
|
sizeof(struct radix_tree_node), 0,
|
|
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
|
|
radix_tree_node_ctor);
|
|
radix_tree_init_maxindex();
|
|
hotcpu_notifier(radix_tree_callback, 0);
|
|
}
|