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c78c66d1dd
The new helper is similar to radix_tree_maybe_preload(), but tries to preload number of nodes required to insert (1 << order) continuous naturally-aligned elements. This is required to push huge pages into pagecache. Link: http://lkml.kernel.org/r/1466021202-61880-24-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1676 lines
44 KiB
C
1676 lines
44 KiB
C
/*
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* Copyright (C) 2001 Momchil Velikov
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* Portions Copyright (C) 2001 Christoph Hellwig
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* Copyright (C) 2005 SGI, Christoph Lameter
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* Copyright (C) 2006 Nick Piggin
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* Copyright (C) 2012 Konstantin Khlebnikov
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* Copyright (C) 2016 Intel, Matthew Wilcox
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* Copyright (C) 2016 Intel, Ross Zwisler
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/radix-tree.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/kmemleak.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/string.h>
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#include <linux/bitops.h>
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#include <linux/rcupdate.h>
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#include <linux/preempt.h> /* in_interrupt() */
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/* Number of nodes in fully populated tree of given height */
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static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
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/*
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* Radix tree node cache.
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*/
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static struct kmem_cache *radix_tree_node_cachep;
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/*
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* The radix tree is variable-height, so an insert operation not only has
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* to build the branch to its corresponding item, it also has to build the
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* branch to existing items if the size has to be increased (by
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* radix_tree_extend).
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*
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* The worst case is a zero height tree with just a single item at index 0,
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* and then inserting an item at index ULONG_MAX. This requires 2 new branches
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* of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
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* Hence:
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*/
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#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
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/*
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* Per-cpu pool of preloaded nodes
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*/
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struct radix_tree_preload {
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unsigned nr;
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/* nodes->private_data points to next preallocated node */
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struct radix_tree_node *nodes;
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};
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static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
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static inline void *node_to_entry(void *ptr)
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{
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return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
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}
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#define RADIX_TREE_RETRY node_to_entry(NULL)
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#ifdef CONFIG_RADIX_TREE_MULTIORDER
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/* Sibling slots point directly to another slot in the same node */
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static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
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{
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void **ptr = node;
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return (parent->slots <= ptr) &&
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(ptr < parent->slots + RADIX_TREE_MAP_SIZE);
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}
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#else
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static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
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{
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return false;
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}
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#endif
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static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
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void **slot)
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{
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return slot - parent->slots;
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}
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static unsigned int radix_tree_descend(struct radix_tree_node *parent,
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struct radix_tree_node **nodep, unsigned long index)
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{
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unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
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void **entry = rcu_dereference_raw(parent->slots[offset]);
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#ifdef CONFIG_RADIX_TREE_MULTIORDER
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if (radix_tree_is_internal_node(entry)) {
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unsigned long siboff = get_slot_offset(parent, entry);
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if (siboff < RADIX_TREE_MAP_SIZE) {
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offset = siboff;
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entry = rcu_dereference_raw(parent->slots[offset]);
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}
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}
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#endif
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*nodep = (void *)entry;
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return offset;
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}
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static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
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{
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return root->gfp_mask & __GFP_BITS_MASK;
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}
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static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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__set_bit(offset, node->tags[tag]);
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}
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static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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__clear_bit(offset, node->tags[tag]);
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}
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static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
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int offset)
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{
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return test_bit(offset, node->tags[tag]);
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}
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static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
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{
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root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
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{
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root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear_all(struct radix_tree_root *root)
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{
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root->gfp_mask &= __GFP_BITS_MASK;
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}
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static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
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{
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return (__force int)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline unsigned root_tags_get(struct radix_tree_root *root)
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{
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return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT;
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}
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/*
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* Returns 1 if any slot in the node has this tag set.
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* Otherwise returns 0.
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*/
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static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
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{
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unsigned idx;
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for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
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if (node->tags[tag][idx])
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return 1;
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}
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return 0;
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}
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/**
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* radix_tree_find_next_bit - find the next set bit in a memory region
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*
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* @addr: The address to base the search on
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* @size: The bitmap size in bits
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* @offset: The bitnumber to start searching at
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*
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* Unrollable variant of find_next_bit() for constant size arrays.
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* Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
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* Returns next bit offset, or size if nothing found.
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*/
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static __always_inline unsigned long
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radix_tree_find_next_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset)
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{
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if (!__builtin_constant_p(size))
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return find_next_bit(addr, size, offset);
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if (offset < size) {
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unsigned long tmp;
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addr += offset / BITS_PER_LONG;
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tmp = *addr >> (offset % BITS_PER_LONG);
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if (tmp)
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return __ffs(tmp) + offset;
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offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
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while (offset < size) {
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tmp = *++addr;
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if (tmp)
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return __ffs(tmp) + offset;
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offset += BITS_PER_LONG;
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}
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}
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return size;
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}
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#ifndef __KERNEL__
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static void dump_node(struct radix_tree_node *node, unsigned long index)
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{
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unsigned long i;
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pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n",
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node, node->offset,
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node->tags[0][0], node->tags[1][0], node->tags[2][0],
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node->shift, node->count, node->parent);
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for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
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unsigned long first = index | (i << node->shift);
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unsigned long last = first | ((1UL << node->shift) - 1);
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void *entry = node->slots[i];
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if (!entry)
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continue;
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if (is_sibling_entry(node, entry)) {
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pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n",
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entry, i,
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*(void **)entry_to_node(entry),
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first, last);
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} else if (!radix_tree_is_internal_node(entry)) {
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pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
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entry, i, first, last);
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} else {
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dump_node(entry_to_node(entry), first);
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}
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}
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}
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/* For debug */
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static void radix_tree_dump(struct radix_tree_root *root)
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{
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pr_debug("radix root: %p rnode %p tags %x\n",
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root, root->rnode,
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root->gfp_mask >> __GFP_BITS_SHIFT);
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if (!radix_tree_is_internal_node(root->rnode))
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return;
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dump_node(entry_to_node(root->rnode), 0);
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}
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#endif
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/*
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* This assumes that the caller has performed appropriate preallocation, and
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* that the caller has pinned this thread of control to the current CPU.
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*/
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static struct radix_tree_node *
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radix_tree_node_alloc(struct radix_tree_root *root)
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{
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struct radix_tree_node *ret = NULL;
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gfp_t gfp_mask = root_gfp_mask(root);
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/*
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* Preload code isn't irq safe and it doesn't make sense to use
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* preloading during an interrupt anyway as all the allocations have
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* to be atomic. So just do normal allocation when in interrupt.
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*/
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if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
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struct radix_tree_preload *rtp;
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/*
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* Even if the caller has preloaded, try to allocate from the
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* cache first for the new node to get accounted.
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*/
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ret = kmem_cache_alloc(radix_tree_node_cachep,
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gfp_mask | __GFP_ACCOUNT | __GFP_NOWARN);
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if (ret)
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goto out;
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/*
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* Provided the caller has preloaded here, we will always
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* succeed in getting a node here (and never reach
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* kmem_cache_alloc)
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*/
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rtp = this_cpu_ptr(&radix_tree_preloads);
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if (rtp->nr) {
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ret = rtp->nodes;
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rtp->nodes = ret->private_data;
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ret->private_data = NULL;
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rtp->nr--;
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}
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/*
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* Update the allocation stack trace as this is more useful
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* for debugging.
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*/
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kmemleak_update_trace(ret);
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goto out;
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}
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ret = kmem_cache_alloc(radix_tree_node_cachep,
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gfp_mask | __GFP_ACCOUNT);
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out:
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BUG_ON(radix_tree_is_internal_node(ret));
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return ret;
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}
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static void radix_tree_node_rcu_free(struct rcu_head *head)
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{
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struct radix_tree_node *node =
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container_of(head, struct radix_tree_node, rcu_head);
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int i;
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/*
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* must only free zeroed nodes into the slab. radix_tree_shrink
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* can leave us with a non-NULL entry in the first slot, so clear
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* that here to make sure.
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*/
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for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
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tag_clear(node, i, 0);
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node->slots[0] = NULL;
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node->count = 0;
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kmem_cache_free(radix_tree_node_cachep, node);
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}
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static inline void
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radix_tree_node_free(struct radix_tree_node *node)
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{
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call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
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}
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/*
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* Load up this CPU's radix_tree_node buffer with sufficient objects to
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* ensure that the addition of a single element in the tree cannot fail. On
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* success, return zero, with preemption disabled. On error, return -ENOMEM
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* with preemption not disabled.
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*
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* To make use of this facility, the radix tree must be initialised without
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* __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
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*/
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static int __radix_tree_preload(gfp_t gfp_mask, int nr)
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{
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struct radix_tree_preload *rtp;
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struct radix_tree_node *node;
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int ret = -ENOMEM;
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preempt_disable();
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rtp = this_cpu_ptr(&radix_tree_preloads);
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while (rtp->nr < nr) {
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preempt_enable();
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node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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if (node == NULL)
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goto out;
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preempt_disable();
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rtp = this_cpu_ptr(&radix_tree_preloads);
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if (rtp->nr < nr) {
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node->private_data = rtp->nodes;
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rtp->nodes = node;
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rtp->nr++;
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} else {
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kmem_cache_free(radix_tree_node_cachep, node);
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}
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}
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ret = 0;
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out:
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return ret;
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}
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/*
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* Load up this CPU's radix_tree_node buffer with sufficient objects to
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* ensure that the addition of a single element in the tree cannot fail. On
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* success, return zero, with preemption disabled. On error, return -ENOMEM
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* with preemption not disabled.
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*
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* To make use of this facility, the radix tree must be initialised without
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* __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
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*/
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int radix_tree_preload(gfp_t gfp_mask)
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{
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/* Warn on non-sensical use... */
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WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
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return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
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}
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EXPORT_SYMBOL(radix_tree_preload);
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/*
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* The same as above function, except we don't guarantee preloading happens.
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* We do it, if we decide it helps. On success, return zero with preemption
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* disabled. On error, return -ENOMEM with preemption not disabled.
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*/
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int radix_tree_maybe_preload(gfp_t gfp_mask)
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{
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if (gfpflags_allow_blocking(gfp_mask))
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return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
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/* Preloading doesn't help anything with this gfp mask, skip it */
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preempt_disable();
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return 0;
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}
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EXPORT_SYMBOL(radix_tree_maybe_preload);
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/*
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* The same as function above, but preload number of nodes required to insert
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* (1 << order) continuous naturally-aligned elements.
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*/
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int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
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{
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unsigned long nr_subtrees;
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int nr_nodes, subtree_height;
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/* Preloading doesn't help anything with this gfp mask, skip it */
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if (!gfpflags_allow_blocking(gfp_mask)) {
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preempt_disable();
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return 0;
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}
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/*
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* Calculate number and height of fully populated subtrees it takes to
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* store (1 << order) elements.
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*/
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nr_subtrees = 1 << order;
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for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
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subtree_height++)
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nr_subtrees >>= RADIX_TREE_MAP_SHIFT;
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/*
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* The worst case is zero height tree with a single item at index 0 and
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* then inserting items starting at ULONG_MAX - (1 << order).
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*
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* This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
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* 0-index item.
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*/
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nr_nodes = RADIX_TREE_MAX_PATH;
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/* Plus branch to fully populated subtrees. */
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nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;
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/* Root node is shared. */
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nr_nodes--;
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/* Plus nodes required to build subtrees. */
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nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];
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return __radix_tree_preload(gfp_mask, nr_nodes);
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}
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|
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/*
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* The maximum index which can be stored in a radix tree
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*/
|
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static inline unsigned long shift_maxindex(unsigned int shift)
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{
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return (RADIX_TREE_MAP_SIZE << shift) - 1;
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}
|
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|
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static inline unsigned long node_maxindex(struct radix_tree_node *node)
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{
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return shift_maxindex(node->shift);
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}
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|
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static unsigned radix_tree_load_root(struct radix_tree_root *root,
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struct radix_tree_node **nodep, unsigned long *maxindex)
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{
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struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
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*nodep = node;
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|
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if (likely(radix_tree_is_internal_node(node))) {
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node = entry_to_node(node);
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*maxindex = node_maxindex(node);
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return node->shift + RADIX_TREE_MAP_SHIFT;
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}
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|
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*maxindex = 0;
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return 0;
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}
|
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|
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/*
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* Extend a radix tree so it can store key @index.
|
|
*/
|
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static int radix_tree_extend(struct radix_tree_root *root,
|
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unsigned long index, unsigned int shift)
|
|
{
|
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struct radix_tree_node *slot;
|
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unsigned int maxshift;
|
|
int tag;
|
|
|
|
/* Figure out what the shift should be. */
|
|
maxshift = shift;
|
|
while (index > shift_maxindex(maxshift))
|
|
maxshift += RADIX_TREE_MAP_SHIFT;
|
|
|
|
slot = root->rnode;
|
|
if (!slot)
|
|
goto out;
|
|
|
|
do {
|
|
struct radix_tree_node *node = radix_tree_node_alloc(root);
|
|
|
|
if (!node)
|
|
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);
|
|
}
|
|
|
|
BUG_ON(shift > BITS_PER_LONG);
|
|
node->shift = shift;
|
|
node->offset = 0;
|
|
node->count = 1;
|
|
node->parent = NULL;
|
|
if (radix_tree_is_internal_node(slot))
|
|
entry_to_node(slot)->parent = node;
|
|
node->slots[0] = slot;
|
|
slot = node_to_entry(node);
|
|
rcu_assign_pointer(root->rnode, slot);
|
|
shift += RADIX_TREE_MAP_SHIFT;
|
|
} while (shift <= maxshift);
|
|
out:
|
|
return maxshift + RADIX_TREE_MAP_SHIFT;
|
|
}
|
|
|
|
/**
|
|
* __radix_tree_create - create a slot in a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @order: index occupies 2^order aligned slots
|
|
* @nodep: returns node
|
|
* @slotp: returns slot
|
|
*
|
|
* Create, if necessary, and return the node and slot for an item
|
|
* at position @index in the radix tree @root.
|
|
*
|
|
* Until there is more than one item in the tree, no nodes are
|
|
* allocated and @root->rnode is used as a direct slot instead of
|
|
* pointing to a node, in which case *@nodep will be NULL.
|
|
*
|
|
* Returns -ENOMEM, or 0 for success.
|
|
*/
|
|
int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
|
|
unsigned order, struct radix_tree_node **nodep,
|
|
void ***slotp)
|
|
{
|
|
struct radix_tree_node *node = NULL, *child;
|
|
void **slot = (void **)&root->rnode;
|
|
unsigned long maxindex;
|
|
unsigned int shift, offset = 0;
|
|
unsigned long max = index | ((1UL << order) - 1);
|
|
|
|
shift = radix_tree_load_root(root, &child, &maxindex);
|
|
|
|
/* Make sure the tree is high enough. */
|
|
if (max > maxindex) {
|
|
int error = radix_tree_extend(root, max, shift);
|
|
if (error < 0)
|
|
return error;
|
|
shift = error;
|
|
child = root->rnode;
|
|
if (order == shift)
|
|
shift += RADIX_TREE_MAP_SHIFT;
|
|
}
|
|
|
|
while (shift > order) {
|
|
shift -= RADIX_TREE_MAP_SHIFT;
|
|
if (child == NULL) {
|
|
/* Have to add a child node. */
|
|
child = radix_tree_node_alloc(root);
|
|
if (!child)
|
|
return -ENOMEM;
|
|
child->shift = shift;
|
|
child->offset = offset;
|
|
child->parent = node;
|
|
rcu_assign_pointer(*slot, node_to_entry(child));
|
|
if (node)
|
|
node->count++;
|
|
} else if (!radix_tree_is_internal_node(child))
|
|
break;
|
|
|
|
/* Go a level down */
|
|
node = entry_to_node(child);
|
|
offset = radix_tree_descend(node, &child, index);
|
|
slot = &node->slots[offset];
|
|
}
|
|
|
|
#ifdef CONFIG_RADIX_TREE_MULTIORDER
|
|
/* Insert pointers to the canonical entry */
|
|
if (order > shift) {
|
|
unsigned i, n = 1 << (order - shift);
|
|
offset = offset & ~(n - 1);
|
|
slot = &node->slots[offset];
|
|
child = node_to_entry(slot);
|
|
for (i = 0; i < n; i++) {
|
|
if (slot[i])
|
|
return -EEXIST;
|
|
}
|
|
|
|
for (i = 1; i < n; i++) {
|
|
rcu_assign_pointer(slot[i], child);
|
|
node->count++;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
if (nodep)
|
|
*nodep = node;
|
|
if (slotp)
|
|
*slotp = slot;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* __radix_tree_insert - insert into a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @order: key covers the 2^order indices around index
|
|
* @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,
|
|
unsigned order, void *item)
|
|
{
|
|
struct radix_tree_node *node;
|
|
void **slot;
|
|
int error;
|
|
|
|
BUG_ON(radix_tree_is_internal_node(item));
|
|
|
|
error = __radix_tree_create(root, index, order, &node, &slot);
|
|
if (error)
|
|
return error;
|
|
if (*slot != NULL)
|
|
return -EEXIST;
|
|
rcu_assign_pointer(*slot, item);
|
|
|
|
if (node) {
|
|
unsigned offset = get_slot_offset(node, slot);
|
|
node->count++;
|
|
BUG_ON(tag_get(node, 0, offset));
|
|
BUG_ON(tag_get(node, 1, offset));
|
|
BUG_ON(tag_get(node, 2, offset));
|
|
} else {
|
|
BUG_ON(root_tags_get(root));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(__radix_tree_insert);
|
|
|
|
/**
|
|
* __radix_tree_lookup - lookup an item in a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @nodep: returns node
|
|
* @slotp: returns slot
|
|
*
|
|
* Lookup and return the item at position @index in the radix
|
|
* tree @root.
|
|
*
|
|
* Until there is more than one item in the tree, no nodes are
|
|
* allocated and @root->rnode is used as a direct slot instead of
|
|
* pointing to a node, in which case *@nodep will be NULL.
|
|
*/
|
|
void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
|
|
struct radix_tree_node **nodep, void ***slotp)
|
|
{
|
|
struct radix_tree_node *node, *parent;
|
|
unsigned long maxindex;
|
|
void **slot;
|
|
|
|
restart:
|
|
parent = NULL;
|
|
slot = (void **)&root->rnode;
|
|
radix_tree_load_root(root, &node, &maxindex);
|
|
if (index > maxindex)
|
|
return NULL;
|
|
|
|
while (radix_tree_is_internal_node(node)) {
|
|
unsigned offset;
|
|
|
|
if (node == RADIX_TREE_RETRY)
|
|
goto restart;
|
|
parent = entry_to_node(node);
|
|
offset = radix_tree_descend(parent, &node, index);
|
|
slot = parent->slots + offset;
|
|
}
|
|
|
|
if (nodep)
|
|
*nodep = parent;
|
|
if (slotp)
|
|
*slotp = slot;
|
|
return 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)
|
|
{
|
|
void **slot;
|
|
|
|
if (!__radix_tree_lookup(root, index, NULL, &slot))
|
|
return NULL;
|
|
return slot;
|
|
}
|
|
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(root, index, NULL, NULL);
|
|
}
|
|
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)
|
|
{
|
|
struct radix_tree_node *node, *parent;
|
|
unsigned long maxindex;
|
|
|
|
radix_tree_load_root(root, &node, &maxindex);
|
|
BUG_ON(index > maxindex);
|
|
|
|
while (radix_tree_is_internal_node(node)) {
|
|
unsigned offset;
|
|
|
|
parent = entry_to_node(node);
|
|
offset = radix_tree_descend(parent, &node, index);
|
|
BUG_ON(!node);
|
|
|
|
if (!tag_get(parent, tag, offset))
|
|
tag_set(parent, tag, offset);
|
|
}
|
|
|
|
/* set the root's tag bit */
|
|
if (!root_tag_get(root, tag))
|
|
root_tag_set(root, tag);
|
|
|
|
return node;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_set);
|
|
|
|
static void node_tag_clear(struct radix_tree_root *root,
|
|
struct radix_tree_node *node,
|
|
unsigned int tag, unsigned int offset)
|
|
{
|
|
while (node) {
|
|
if (!tag_get(node, tag, offset))
|
|
return;
|
|
tag_clear(node, tag, offset);
|
|
if (any_tag_set(node, tag))
|
|
return;
|
|
|
|
offset = node->offset;
|
|
node = node->parent;
|
|
}
|
|
|
|
/* clear the root's tag bit */
|
|
if (root_tag_get(root, tag))
|
|
root_tag_clear(root, tag);
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
struct radix_tree_node *node, *parent;
|
|
unsigned long maxindex;
|
|
int uninitialized_var(offset);
|
|
|
|
radix_tree_load_root(root, &node, &maxindex);
|
|
if (index > maxindex)
|
|
return NULL;
|
|
|
|
parent = NULL;
|
|
|
|
while (radix_tree_is_internal_node(node)) {
|
|
parent = entry_to_node(node);
|
|
offset = radix_tree_descend(parent, &node, index);
|
|
}
|
|
|
|
if (node)
|
|
node_tag_clear(root, parent, tag, offset);
|
|
|
|
return node;
|
|
}
|
|
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)
|
|
{
|
|
struct radix_tree_node *node, *parent;
|
|
unsigned long maxindex;
|
|
|
|
if (!root_tag_get(root, tag))
|
|
return 0;
|
|
|
|
radix_tree_load_root(root, &node, &maxindex);
|
|
if (index > maxindex)
|
|
return 0;
|
|
if (node == NULL)
|
|
return 0;
|
|
|
|
while (radix_tree_is_internal_node(node)) {
|
|
unsigned offset;
|
|
|
|
parent = entry_to_node(node);
|
|
offset = radix_tree_descend(parent, &node, index);
|
|
|
|
if (!node)
|
|
return 0;
|
|
if (!tag_get(parent, tag, offset))
|
|
return 0;
|
|
if (node == RADIX_TREE_RETRY)
|
|
break;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_tag_get);
|
|
|
|
static inline void __set_iter_shift(struct radix_tree_iter *iter,
|
|
unsigned int shift)
|
|
{
|
|
#ifdef CONFIG_RADIX_TREE_MULTIORDER
|
|
iter->shift = shift;
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* 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 tag = flags & RADIX_TREE_ITER_TAG_MASK;
|
|
struct radix_tree_node *node, *child;
|
|
unsigned long index, offset, maxindex;
|
|
|
|
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.
|
|
*
|
|
* This condition also used by radix_tree_next_slot() to stop
|
|
* contiguous iterating, and forbid swithing to the next chunk.
|
|
*/
|
|
index = iter->next_index;
|
|
if (!index && iter->index)
|
|
return NULL;
|
|
|
|
restart:
|
|
radix_tree_load_root(root, &child, &maxindex);
|
|
if (index > maxindex)
|
|
return NULL;
|
|
if (!child)
|
|
return NULL;
|
|
|
|
if (!radix_tree_is_internal_node(child)) {
|
|
/* Single-slot tree */
|
|
iter->index = index;
|
|
iter->next_index = maxindex + 1;
|
|
iter->tags = 1;
|
|
__set_iter_shift(iter, 0);
|
|
return (void **)&root->rnode;
|
|
}
|
|
|
|
do {
|
|
node = entry_to_node(child);
|
|
offset = radix_tree_descend(node, &child, index);
|
|
|
|
if ((flags & RADIX_TREE_ITER_TAGGED) ?
|
|
!tag_get(node, tag, offset) : !child) {
|
|
/* 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) {
|
|
void *slot = node->slots[offset];
|
|
if (is_sibling_entry(node, slot))
|
|
continue;
|
|
if (slot)
|
|
break;
|
|
}
|
|
index &= ~node_maxindex(node);
|
|
index += offset << node->shift;
|
|
/* Overflow after ~0UL */
|
|
if (!index)
|
|
return NULL;
|
|
if (offset == RADIX_TREE_MAP_SIZE)
|
|
goto restart;
|
|
child = rcu_dereference_raw(node->slots[offset]);
|
|
}
|
|
|
|
if ((child == NULL) || (child == RADIX_TREE_RETRY))
|
|
goto restart;
|
|
} while (radix_tree_is_internal_node(child));
|
|
|
|
/* Update the iterator state */
|
|
iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
|
|
iter->next_index = (index | node_maxindex(node)) + 1;
|
|
__set_iter_shift(iter, node->shift);
|
|
|
|
/* 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 the 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)
|
|
{
|
|
struct radix_tree_node *parent, *node, *child;
|
|
unsigned long maxindex;
|
|
unsigned long tagged = 0;
|
|
unsigned long index = *first_indexp;
|
|
|
|
radix_tree_load_root(root, &child, &maxindex);
|
|
last_index = min(last_index, maxindex);
|
|
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 (!radix_tree_is_internal_node(child)) {
|
|
*first_indexp = last_index + 1;
|
|
root_tag_set(root, settag);
|
|
return 1;
|
|
}
|
|
|
|
node = entry_to_node(child);
|
|
|
|
for (;;) {
|
|
unsigned offset = radix_tree_descend(node, &child, index);
|
|
if (!child)
|
|
goto next;
|
|
if (!tag_get(node, iftag, offset))
|
|
goto next;
|
|
/* Sibling slots never have tags set on them */
|
|
if (radix_tree_is_internal_node(child)) {
|
|
node = entry_to_node(child);
|
|
continue;
|
|
}
|
|
|
|
/* tag the leaf */
|
|
tagged++;
|
|
tag_set(node, settag, offset);
|
|
|
|
/* walk back up the path tagging interior nodes */
|
|
parent = node;
|
|
for (;;) {
|
|
offset = parent->offset;
|
|
parent = parent->parent;
|
|
if (!parent)
|
|
break;
|
|
/* stop if we find a node with the tag already set */
|
|
if (tag_get(parent, settag, offset))
|
|
break;
|
|
tag_set(parent, settag, offset);
|
|
}
|
|
next:
|
|
/* Go to next entry in node */
|
|
index = ((index >> node->shift) + 1) << node->shift;
|
|
/* Overflow can happen when last_index is ~0UL... */
|
|
if (index > last_index || !index)
|
|
break;
|
|
offset = (index >> node->shift) & RADIX_TREE_MAP_MASK;
|
|
while (offset == 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.
|
|
*/
|
|
node = node->parent;
|
|
offset = (index >> node->shift) & RADIX_TREE_MAP_MASK;
|
|
}
|
|
if (is_sibling_entry(node, node->slots[offset]))
|
|
goto next;
|
|
if (tagged >= nr_to_tag)
|
|
break;
|
|
}
|
|
/*
|
|
* 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_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)
|
|
{
|
|
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] = rcu_dereference_raw(*slot);
|
|
if (!results[ret])
|
|
continue;
|
|
if (radix_tree_is_internal_node(results[ret])) {
|
|
slot = radix_tree_iter_retry(&iter);
|
|
continue;
|
|
}
|
|
if (++ret == max_items)
|
|
break;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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] = rcu_dereference_raw(*slot);
|
|
if (!results[ret])
|
|
continue;
|
|
if (radix_tree_is_internal_node(results[ret])) {
|
|
slot = radix_tree_iter_retry(&iter);
|
|
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() */
|
|
|
|
struct locate_info {
|
|
unsigned long found_index;
|
|
bool stop;
|
|
};
|
|
|
|
/*
|
|
* 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, struct locate_info *info)
|
|
{
|
|
unsigned long i;
|
|
|
|
do {
|
|
unsigned int shift = slot->shift;
|
|
|
|
for (i = (index >> shift) & RADIX_TREE_MAP_MASK;
|
|
i < RADIX_TREE_MAP_SIZE;
|
|
i++, index += (1UL << shift)) {
|
|
struct radix_tree_node *node =
|
|
rcu_dereference_raw(slot->slots[i]);
|
|
if (node == RADIX_TREE_RETRY)
|
|
goto out;
|
|
if (!radix_tree_is_internal_node(node)) {
|
|
if (node == item) {
|
|
info->found_index = index;
|
|
info->stop = true;
|
|
goto out;
|
|
}
|
|
continue;
|
|
}
|
|
node = entry_to_node(node);
|
|
if (is_sibling_entry(slot, node))
|
|
continue;
|
|
slot = node;
|
|
break;
|
|
}
|
|
} while (i < RADIX_TREE_MAP_SIZE);
|
|
|
|
out:
|
|
if ((index == 0) && (i == RADIX_TREE_MAP_SIZE))
|
|
info->stop = true;
|
|
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;
|
|
struct locate_info info = {
|
|
.found_index = -1,
|
|
.stop = false,
|
|
};
|
|
|
|
do {
|
|
rcu_read_lock();
|
|
node = rcu_dereference_raw(root->rnode);
|
|
if (!radix_tree_is_internal_node(node)) {
|
|
rcu_read_unlock();
|
|
if (node == item)
|
|
info.found_index = 0;
|
|
break;
|
|
}
|
|
|
|
node = entry_to_node(node);
|
|
|
|
max_index = node_maxindex(node);
|
|
if (cur_index > max_index) {
|
|
rcu_read_unlock();
|
|
break;
|
|
}
|
|
|
|
cur_index = __locate(node, item, cur_index, &info);
|
|
rcu_read_unlock();
|
|
cond_resched();
|
|
} while (!info.stop && cur_index <= max_index);
|
|
|
|
return info.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 radix tree to minimum height
|
|
* @root radix tree root
|
|
*/
|
|
static inline bool radix_tree_shrink(struct radix_tree_root *root)
|
|
{
|
|
bool shrunk = false;
|
|
|
|
for (;;) {
|
|
struct radix_tree_node *node = root->rnode;
|
|
struct radix_tree_node *child;
|
|
|
|
if (!radix_tree_is_internal_node(node))
|
|
break;
|
|
node = entry_to_node(node);
|
|
|
|
/*
|
|
* The candidate node has more than one child, or its child
|
|
* is not at the leftmost slot, or the child is a multiorder
|
|
* entry, we cannot shrink.
|
|
*/
|
|
if (node->count != 1)
|
|
break;
|
|
child = node->slots[0];
|
|
if (!child)
|
|
break;
|
|
if (!radix_tree_is_internal_node(child) && node->shift)
|
|
break;
|
|
|
|
if (radix_tree_is_internal_node(child))
|
|
entry_to_node(child)->parent = NULL;
|
|
|
|
/*
|
|
* 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
|
|
* (node->slots[0]), it will be safe to dereference the new
|
|
* one (root->rnode) as far as dependent read barriers go.
|
|
*/
|
|
root->rnode = child;
|
|
|
|
/*
|
|
* 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 has 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 (!radix_tree_is_internal_node(child))
|
|
node->slots[0] = RADIX_TREE_RETRY;
|
|
|
|
radix_tree_node_free(node);
|
|
shrunk = true;
|
|
}
|
|
|
|
return shrunk;
|
|
}
|
|
|
|
/**
|
|
* __radix_tree_delete_node - try to free node after clearing a slot
|
|
* @root: radix tree root
|
|
* @node: node containing @index
|
|
*
|
|
* After clearing the slot at @index in @node from radix tree
|
|
* rooted at @root, call this function to attempt freeing the
|
|
* node and shrinking the tree.
|
|
*
|
|
* Returns %true if @node was freed, %false otherwise.
|
|
*/
|
|
bool __radix_tree_delete_node(struct radix_tree_root *root,
|
|
struct radix_tree_node *node)
|
|
{
|
|
bool deleted = false;
|
|
|
|
do {
|
|
struct radix_tree_node *parent;
|
|
|
|
if (node->count) {
|
|
if (node == entry_to_node(root->rnode))
|
|
deleted |= radix_tree_shrink(root);
|
|
return deleted;
|
|
}
|
|
|
|
parent = node->parent;
|
|
if (parent) {
|
|
parent->slots[node->offset] = NULL;
|
|
parent->count--;
|
|
} else {
|
|
root_tag_clear_all(root);
|
|
root->rnode = NULL;
|
|
}
|
|
|
|
radix_tree_node_free(node);
|
|
deleted = true;
|
|
|
|
node = parent;
|
|
} while (node);
|
|
|
|
return deleted;
|
|
}
|
|
|
|
static inline void delete_sibling_entries(struct radix_tree_node *node,
|
|
void *ptr, unsigned offset)
|
|
{
|
|
#ifdef CONFIG_RADIX_TREE_MULTIORDER
|
|
int i;
|
|
for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
|
|
if (node->slots[offset + i] != ptr)
|
|
break;
|
|
node->slots[offset + i] = NULL;
|
|
node->count--;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* radix_tree_delete_item - delete an item from a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
* @item: expected item
|
|
*
|
|
* Remove @item at @index from the radix tree rooted at @root.
|
|
*
|
|
* Returns the address of the deleted item, or NULL if it was not present
|
|
* or the entry at the given @index was not @item.
|
|
*/
|
|
void *radix_tree_delete_item(struct radix_tree_root *root,
|
|
unsigned long index, void *item)
|
|
{
|
|
struct radix_tree_node *node;
|
|
unsigned int offset;
|
|
void **slot;
|
|
void *entry;
|
|
int tag;
|
|
|
|
entry = __radix_tree_lookup(root, index, &node, &slot);
|
|
if (!entry)
|
|
return NULL;
|
|
|
|
if (item && entry != item)
|
|
return NULL;
|
|
|
|
if (!node) {
|
|
root_tag_clear_all(root);
|
|
root->rnode = NULL;
|
|
return entry;
|
|
}
|
|
|
|
offset = get_slot_offset(node, slot);
|
|
|
|
/* Clear all tags associated with the item to be deleted. */
|
|
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
|
|
node_tag_clear(root, node, tag, offset);
|
|
|
|
delete_sibling_entries(node, node_to_entry(slot), offset);
|
|
node->slots[offset] = NULL;
|
|
node->count--;
|
|
|
|
__radix_tree_delete_node(root, node);
|
|
|
|
return entry;
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_delete_item);
|
|
|
|
/**
|
|
* radix_tree_delete - delete an item from a radix tree
|
|
* @root: radix tree root
|
|
* @index: index key
|
|
*
|
|
* Remove the item at @index from the radix tree rooted at @root.
|
|
*
|
|
* Returns the address of the deleted item, or NULL if it was not present.
|
|
*/
|
|
void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
|
|
{
|
|
return radix_tree_delete_item(root, index, NULL);
|
|
}
|
|
EXPORT_SYMBOL(radix_tree_delete);
|
|
|
|
struct radix_tree_node *radix_tree_replace_clear_tags(
|
|
struct radix_tree_root *root,
|
|
unsigned long index, void *entry)
|
|
{
|
|
struct radix_tree_node *node;
|
|
void **slot;
|
|
|
|
__radix_tree_lookup(root, index, &node, &slot);
|
|
|
|
if (node) {
|
|
unsigned int tag, offset = get_slot_offset(node, slot);
|
|
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
|
|
node_tag_clear(root, node, tag, offset);
|
|
} else {
|
|
/* Clear root node tags */
|
|
root->gfp_mask &= __GFP_BITS_MASK;
|
|
}
|
|
|
|
radix_tree_replace_slot(slot, entry);
|
|
return node;
|
|
}
|
|
|
|
/**
|
|
* 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 *arg)
|
|
{
|
|
struct radix_tree_node *node = arg;
|
|
|
|
memset(node, 0, sizeof(*node));
|
|
INIT_LIST_HEAD(&node->private_list);
|
|
}
|
|
|
|
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_maxnodes(void)
|
|
{
|
|
unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
|
|
unsigned int i, j;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
|
|
height_to_maxindex[i] = __maxindex(i);
|
|
for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
|
|
for (j = i; j > 0; j--)
|
|
height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
|
|
}
|
|
}
|
|
|
|
static int radix_tree_callback(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
int cpu = (long)hcpu;
|
|
struct radix_tree_preload *rtp;
|
|
struct radix_tree_node *node;
|
|
|
|
/* Free per-cpu pool of preloaded nodes */
|
|
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
|
|
rtp = &per_cpu(radix_tree_preloads, cpu);
|
|
while (rtp->nr) {
|
|
node = rtp->nodes;
|
|
rtp->nodes = node->private_data;
|
|
kmem_cache_free(radix_tree_node_cachep, node);
|
|
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_maxnodes();
|
|
hotcpu_notifier(radix_tree_callback, 0);
|
|
}
|