2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2005 SGI, Christoph Lameter
5 * Copyright (C) 2006 Nick Piggin
6 * Copyright (C) 2012 Konstantin Khlebnikov
7 * Copyright (C) 2016 Intel, Matthew Wilcox
8 * Copyright (C) 2016 Intel, Ross Zwisler
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2, or (at
13 * your option) any later version.
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 #include <linux/errno.h>
26 #include <linux/init.h>
27 #include <linux/kernel.h>
28 #include <linux/export.h>
29 #include <linux/radix-tree.h>
30 #include <linux/percpu.h>
31 #include <linux/slab.h>
32 #include <linux/kmemleak.h>
33 #include <linux/notifier.h>
34 #include <linux/cpu.h>
35 #include <linux/string.h>
36 #include <linux/bitops.h>
37 #include <linux/rcupdate.h>
38 #include <linux/preempt.h> /* in_interrupt() */
42 * Radix tree node cache.
44 static struct kmem_cache
*radix_tree_node_cachep
;
47 * The radix tree is variable-height, so an insert operation not only has
48 * to build the branch to its corresponding item, it also has to build the
49 * branch to existing items if the size has to be increased (by
52 * The worst case is a zero height tree with just a single item at index 0,
53 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
54 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
57 #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
60 * Per-cpu pool of preloaded nodes
62 struct radix_tree_preload
{
64 /* nodes->private_data points to next preallocated node */
65 struct radix_tree_node
*nodes
;
67 static DEFINE_PER_CPU(struct radix_tree_preload
, radix_tree_preloads
) = { 0, };
69 static inline void *node_to_entry(void *ptr
)
71 return (void *)((unsigned long)ptr
| RADIX_TREE_INTERNAL_NODE
);
74 #define RADIX_TREE_RETRY node_to_entry(NULL)
76 #ifdef CONFIG_RADIX_TREE_MULTIORDER
77 /* Sibling slots point directly to another slot in the same node */
78 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
81 return (parent
->slots
<= ptr
) &&
82 (ptr
< parent
->slots
+ RADIX_TREE_MAP_SIZE
);
85 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
91 static inline unsigned long get_slot_offset(struct radix_tree_node
*parent
,
94 return slot
- parent
->slots
;
97 static unsigned int radix_tree_descend(struct radix_tree_node
*parent
,
98 struct radix_tree_node
**nodep
, unsigned long index
)
100 unsigned int offset
= (index
>> parent
->shift
) & RADIX_TREE_MAP_MASK
;
101 void **entry
= rcu_dereference_raw(parent
->slots
[offset
]);
103 #ifdef CONFIG_RADIX_TREE_MULTIORDER
104 if (radix_tree_is_internal_node(entry
)) {
105 unsigned long siboff
= get_slot_offset(parent
, entry
);
106 if (siboff
< RADIX_TREE_MAP_SIZE
) {
108 entry
= rcu_dereference_raw(parent
->slots
[offset
]);
113 *nodep
= (void *)entry
;
117 static inline gfp_t
root_gfp_mask(struct radix_tree_root
*root
)
119 return root
->gfp_mask
& __GFP_BITS_MASK
;
122 static inline void tag_set(struct radix_tree_node
*node
, unsigned int tag
,
125 __set_bit(offset
, node
->tags
[tag
]);
128 static inline void tag_clear(struct radix_tree_node
*node
, unsigned int tag
,
131 __clear_bit(offset
, node
->tags
[tag
]);
134 static inline int tag_get(struct radix_tree_node
*node
, unsigned int tag
,
137 return test_bit(offset
, node
->tags
[tag
]);
140 static inline void root_tag_set(struct radix_tree_root
*root
, unsigned int tag
)
142 root
->gfp_mask
|= (__force gfp_t
)(1 << (tag
+ __GFP_BITS_SHIFT
));
145 static inline void root_tag_clear(struct radix_tree_root
*root
, unsigned tag
)
147 root
->gfp_mask
&= (__force gfp_t
)~(1 << (tag
+ __GFP_BITS_SHIFT
));
150 static inline void root_tag_clear_all(struct radix_tree_root
*root
)
152 root
->gfp_mask
&= __GFP_BITS_MASK
;
155 static inline int root_tag_get(struct radix_tree_root
*root
, unsigned int tag
)
157 return (__force
int)root
->gfp_mask
& (1 << (tag
+ __GFP_BITS_SHIFT
));
160 static inline unsigned root_tags_get(struct radix_tree_root
*root
)
162 return (__force
unsigned)root
->gfp_mask
>> __GFP_BITS_SHIFT
;
166 * Returns 1 if any slot in the node has this tag set.
167 * Otherwise returns 0.
169 static inline int any_tag_set(struct radix_tree_node
*node
, unsigned int tag
)
172 for (idx
= 0; idx
< RADIX_TREE_TAG_LONGS
; idx
++) {
173 if (node
->tags
[tag
][idx
])
180 * radix_tree_find_next_bit - find the next set bit in a memory region
182 * @addr: The address to base the search on
183 * @size: The bitmap size in bits
184 * @offset: The bitnumber to start searching at
186 * Unrollable variant of find_next_bit() for constant size arrays.
187 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
188 * Returns next bit offset, or size if nothing found.
190 static __always_inline
unsigned long
191 radix_tree_find_next_bit(const unsigned long *addr
,
192 unsigned long size
, unsigned long offset
)
194 if (!__builtin_constant_p(size
))
195 return find_next_bit(addr
, size
, offset
);
200 addr
+= offset
/ BITS_PER_LONG
;
201 tmp
= *addr
>> (offset
% BITS_PER_LONG
);
203 return __ffs(tmp
) + offset
;
204 offset
= (offset
+ BITS_PER_LONG
) & ~(BITS_PER_LONG
- 1);
205 while (offset
< size
) {
208 return __ffs(tmp
) + offset
;
209 offset
+= BITS_PER_LONG
;
216 static void dump_node(struct radix_tree_node
*node
, unsigned long index
)
220 pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n",
222 node
->tags
[0][0], node
->tags
[1][0], node
->tags
[2][0],
223 node
->shift
, node
->count
, node
->parent
);
225 for (i
= 0; i
< RADIX_TREE_MAP_SIZE
; i
++) {
226 unsigned long first
= index
| (i
<< node
->shift
);
227 unsigned long last
= first
| ((1UL << node
->shift
) - 1);
228 void *entry
= node
->slots
[i
];
231 if (is_sibling_entry(node
, entry
)) {
232 pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n",
234 *(void **)entry_to_node(entry
),
236 } else if (!radix_tree_is_internal_node(entry
)) {
237 pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
238 entry
, i
, first
, last
);
240 dump_node(entry_to_node(entry
), first
);
246 static void radix_tree_dump(struct radix_tree_root
*root
)
248 pr_debug("radix root: %p rnode %p tags %x\n",
250 root
->gfp_mask
>> __GFP_BITS_SHIFT
);
251 if (!radix_tree_is_internal_node(root
->rnode
))
253 dump_node(entry_to_node(root
->rnode
), 0);
258 * This assumes that the caller has performed appropriate preallocation, and
259 * that the caller has pinned this thread of control to the current CPU.
261 static struct radix_tree_node
*
262 radix_tree_node_alloc(struct radix_tree_root
*root
)
264 struct radix_tree_node
*ret
= NULL
;
265 gfp_t gfp_mask
= root_gfp_mask(root
);
268 * Preload code isn't irq safe and it doesn't make sense to use
269 * preloading during an interrupt anyway as all the allocations have
270 * to be atomic. So just do normal allocation when in interrupt.
272 if (!gfpflags_allow_blocking(gfp_mask
) && !in_interrupt()) {
273 struct radix_tree_preload
*rtp
;
276 * Even if the caller has preloaded, try to allocate from the
277 * cache first for the new node to get accounted.
279 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
280 gfp_mask
| __GFP_ACCOUNT
| __GFP_NOWARN
);
285 * Provided the caller has preloaded here, we will always
286 * succeed in getting a node here (and never reach
289 rtp
= this_cpu_ptr(&radix_tree_preloads
);
292 rtp
->nodes
= ret
->private_data
;
293 ret
->private_data
= NULL
;
297 * Update the allocation stack trace as this is more useful
300 kmemleak_update_trace(ret
);
303 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
304 gfp_mask
| __GFP_ACCOUNT
);
306 BUG_ON(radix_tree_is_internal_node(ret
));
310 static void radix_tree_node_rcu_free(struct rcu_head
*head
)
312 struct radix_tree_node
*node
=
313 container_of(head
, struct radix_tree_node
, rcu_head
);
317 * must only free zeroed nodes into the slab. radix_tree_shrink
318 * can leave us with a non-NULL entry in the first slot, so clear
319 * that here to make sure.
321 for (i
= 0; i
< RADIX_TREE_MAX_TAGS
; i
++)
322 tag_clear(node
, i
, 0);
324 node
->slots
[0] = NULL
;
327 kmem_cache_free(radix_tree_node_cachep
, node
);
331 radix_tree_node_free(struct radix_tree_node
*node
)
333 call_rcu(&node
->rcu_head
, radix_tree_node_rcu_free
);
337 * Load up this CPU's radix_tree_node buffer with sufficient objects to
338 * ensure that the addition of a single element in the tree cannot fail. On
339 * success, return zero, with preemption disabled. On error, return -ENOMEM
340 * with preemption not disabled.
342 * To make use of this facility, the radix tree must be initialised without
343 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
345 static int __radix_tree_preload(gfp_t gfp_mask
)
347 struct radix_tree_preload
*rtp
;
348 struct radix_tree_node
*node
;
352 rtp
= this_cpu_ptr(&radix_tree_preloads
);
353 while (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
355 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp_mask
);
359 rtp
= this_cpu_ptr(&radix_tree_preloads
);
360 if (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
361 node
->private_data
= rtp
->nodes
;
365 kmem_cache_free(radix_tree_node_cachep
, node
);
374 * Load up this CPU's radix_tree_node buffer with sufficient objects to
375 * ensure that the addition of a single element in the tree cannot fail. On
376 * success, return zero, with preemption disabled. On error, return -ENOMEM
377 * with preemption not disabled.
379 * To make use of this facility, the radix tree must be initialised without
380 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
382 int radix_tree_preload(gfp_t gfp_mask
)
384 /* Warn on non-sensical use... */
385 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask
));
386 return __radix_tree_preload(gfp_mask
);
388 EXPORT_SYMBOL(radix_tree_preload
);
391 * The same as above function, except we don't guarantee preloading happens.
392 * We do it, if we decide it helps. On success, return zero with preemption
393 * disabled. On error, return -ENOMEM with preemption not disabled.
395 int radix_tree_maybe_preload(gfp_t gfp_mask
)
397 if (gfpflags_allow_blocking(gfp_mask
))
398 return __radix_tree_preload(gfp_mask
);
399 /* Preloading doesn't help anything with this gfp mask, skip it */
403 EXPORT_SYMBOL(radix_tree_maybe_preload
);
406 * The maximum index which can be stored in a radix tree
408 static inline unsigned long shift_maxindex(unsigned int shift
)
410 return (RADIX_TREE_MAP_SIZE
<< shift
) - 1;
413 static inline unsigned long node_maxindex(struct radix_tree_node
*node
)
415 return shift_maxindex(node
->shift
);
418 static unsigned radix_tree_load_root(struct radix_tree_root
*root
,
419 struct radix_tree_node
**nodep
, unsigned long *maxindex
)
421 struct radix_tree_node
*node
= rcu_dereference_raw(root
->rnode
);
425 if (likely(radix_tree_is_internal_node(node
))) {
426 node
= entry_to_node(node
);
427 *maxindex
= node_maxindex(node
);
428 return node
->shift
+ RADIX_TREE_MAP_SHIFT
;
436 * Extend a radix tree so it can store key @index.
438 static int radix_tree_extend(struct radix_tree_root
*root
,
439 unsigned long index
, unsigned int shift
)
441 struct radix_tree_node
*slot
;
442 unsigned int maxshift
;
445 /* Figure out what the shift should be. */
447 while (index
> shift_maxindex(maxshift
))
448 maxshift
+= RADIX_TREE_MAP_SHIFT
;
455 struct radix_tree_node
*node
= radix_tree_node_alloc(root
);
460 /* Propagate the aggregated tag info into the new root */
461 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
462 if (root_tag_get(root
, tag
))
463 tag_set(node
, tag
, 0);
466 BUG_ON(shift
> BITS_PER_LONG
);
471 if (radix_tree_is_internal_node(slot
))
472 entry_to_node(slot
)->parent
= node
;
473 node
->slots
[0] = slot
;
474 slot
= node_to_entry(node
);
475 rcu_assign_pointer(root
->rnode
, slot
);
476 shift
+= RADIX_TREE_MAP_SHIFT
;
477 } while (shift
<= maxshift
);
479 return maxshift
+ RADIX_TREE_MAP_SHIFT
;
483 * __radix_tree_create - create a slot in a radix tree
484 * @root: radix tree root
486 * @order: index occupies 2^order aligned slots
487 * @nodep: returns node
488 * @slotp: returns slot
490 * Create, if necessary, and return the node and slot for an item
491 * at position @index in the radix tree @root.
493 * Until there is more than one item in the tree, no nodes are
494 * allocated and @root->rnode is used as a direct slot instead of
495 * pointing to a node, in which case *@nodep will be NULL.
497 * Returns -ENOMEM, or 0 for success.
499 int __radix_tree_create(struct radix_tree_root
*root
, unsigned long index
,
500 unsigned order
, struct radix_tree_node
**nodep
,
503 struct radix_tree_node
*node
= NULL
, *child
;
504 void **slot
= (void **)&root
->rnode
;
505 unsigned long maxindex
;
506 unsigned int shift
, offset
= 0;
507 unsigned long max
= index
| ((1UL << order
) - 1);
509 shift
= radix_tree_load_root(root
, &child
, &maxindex
);
511 /* Make sure the tree is high enough. */
512 if (max
> maxindex
) {
513 int error
= radix_tree_extend(root
, max
, shift
);
519 shift
+= RADIX_TREE_MAP_SHIFT
;
522 while (shift
> order
) {
523 shift
-= RADIX_TREE_MAP_SHIFT
;
525 /* Have to add a child node. */
526 child
= radix_tree_node_alloc(root
);
529 child
->shift
= shift
;
530 child
->offset
= offset
;
531 child
->parent
= node
;
532 rcu_assign_pointer(*slot
, node_to_entry(child
));
535 } else if (!radix_tree_is_internal_node(child
))
538 /* Go a level down */
539 node
= entry_to_node(child
);
540 offset
= radix_tree_descend(node
, &child
, index
);
541 slot
= &node
->slots
[offset
];
544 #ifdef CONFIG_RADIX_TREE_MULTIORDER
545 /* Insert pointers to the canonical entry */
547 unsigned i
, n
= 1 << (order
- shift
);
548 offset
= offset
& ~(n
- 1);
549 slot
= &node
->slots
[offset
];
550 child
= node_to_entry(slot
);
551 for (i
= 0; i
< n
; i
++) {
556 for (i
= 1; i
< n
; i
++) {
557 rcu_assign_pointer(slot
[i
], child
);
571 * __radix_tree_insert - insert into a radix tree
572 * @root: radix tree root
574 * @order: key covers the 2^order indices around index
575 * @item: item to insert
577 * Insert an item into the radix tree at position @index.
579 int __radix_tree_insert(struct radix_tree_root
*root
, unsigned long index
,
580 unsigned order
, void *item
)
582 struct radix_tree_node
*node
;
586 BUG_ON(radix_tree_is_internal_node(item
));
588 error
= __radix_tree_create(root
, index
, order
, &node
, &slot
);
593 rcu_assign_pointer(*slot
, item
);
596 unsigned offset
= get_slot_offset(node
, slot
);
598 BUG_ON(tag_get(node
, 0, offset
));
599 BUG_ON(tag_get(node
, 1, offset
));
600 BUG_ON(tag_get(node
, 2, offset
));
602 BUG_ON(root_tags_get(root
));
607 EXPORT_SYMBOL(__radix_tree_insert
);
610 * __radix_tree_lookup - lookup an item in a radix tree
611 * @root: radix tree root
613 * @nodep: returns node
614 * @slotp: returns slot
616 * Lookup and return the item at position @index in the radix
619 * Until there is more than one item in the tree, no nodes are
620 * allocated and @root->rnode is used as a direct slot instead of
621 * pointing to a node, in which case *@nodep will be NULL.
623 void *__radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
,
624 struct radix_tree_node
**nodep
, void ***slotp
)
626 struct radix_tree_node
*node
, *parent
;
627 unsigned long maxindex
;
632 slot
= (void **)&root
->rnode
;
633 radix_tree_load_root(root
, &node
, &maxindex
);
634 if (index
> maxindex
)
637 while (radix_tree_is_internal_node(node
)) {
640 if (node
== RADIX_TREE_RETRY
)
642 parent
= entry_to_node(node
);
643 offset
= radix_tree_descend(parent
, &node
, index
);
644 slot
= parent
->slots
+ offset
;
655 * radix_tree_lookup_slot - lookup a slot in a radix tree
656 * @root: radix tree root
659 * Returns: the slot corresponding to the position @index in the
660 * radix tree @root. This is useful for update-if-exists operations.
662 * This function can be called under rcu_read_lock iff the slot is not
663 * modified by radix_tree_replace_slot, otherwise it must be called
664 * exclusive from other writers. Any dereference of the slot must be done
665 * using radix_tree_deref_slot.
667 void **radix_tree_lookup_slot(struct radix_tree_root
*root
, unsigned long index
)
671 if (!__radix_tree_lookup(root
, index
, NULL
, &slot
))
675 EXPORT_SYMBOL(radix_tree_lookup_slot
);
678 * radix_tree_lookup - perform lookup operation on a radix tree
679 * @root: radix tree root
682 * Lookup the item at the position @index in the radix tree @root.
684 * This function can be called under rcu_read_lock, however the caller
685 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
686 * them safely). No RCU barriers are required to access or modify the
687 * returned item, however.
689 void *radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
)
691 return __radix_tree_lookup(root
, index
, NULL
, NULL
);
693 EXPORT_SYMBOL(radix_tree_lookup
);
696 * radix_tree_tag_set - set a tag on a radix tree node
697 * @root: radix tree root
701 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
702 * corresponding to @index in the radix tree. From
703 * the root all the way down to the leaf node.
705 * Returns the address of the tagged item. Setting a tag on a not-present
708 void *radix_tree_tag_set(struct radix_tree_root
*root
,
709 unsigned long index
, unsigned int tag
)
711 struct radix_tree_node
*node
, *parent
;
712 unsigned long maxindex
;
714 radix_tree_load_root(root
, &node
, &maxindex
);
715 BUG_ON(index
> maxindex
);
717 while (radix_tree_is_internal_node(node
)) {
720 parent
= entry_to_node(node
);
721 offset
= radix_tree_descend(parent
, &node
, index
);
724 if (!tag_get(parent
, tag
, offset
))
725 tag_set(parent
, tag
, offset
);
728 /* set the root's tag bit */
729 if (!root_tag_get(root
, tag
))
730 root_tag_set(root
, tag
);
734 EXPORT_SYMBOL(radix_tree_tag_set
);
736 static void node_tag_clear(struct radix_tree_root
*root
,
737 struct radix_tree_node
*node
,
738 unsigned int tag
, unsigned int offset
)
741 if (!tag_get(node
, tag
, offset
))
743 tag_clear(node
, tag
, offset
);
744 if (any_tag_set(node
, tag
))
747 offset
= node
->offset
;
751 /* clear the root's tag bit */
752 if (root_tag_get(root
, tag
))
753 root_tag_clear(root
, tag
);
757 * radix_tree_tag_clear - clear a tag on a radix tree node
758 * @root: radix tree root
762 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
763 * corresponding to @index in the radix tree. If this causes
764 * the leaf node to have no tags set then clear the tag in the
765 * next-to-leaf node, etc.
767 * Returns the address of the tagged item on success, else NULL. ie:
768 * has the same return value and semantics as radix_tree_lookup().
770 void *radix_tree_tag_clear(struct radix_tree_root
*root
,
771 unsigned long index
, unsigned int tag
)
773 struct radix_tree_node
*node
, *parent
;
774 unsigned long maxindex
;
775 int uninitialized_var(offset
);
777 radix_tree_load_root(root
, &node
, &maxindex
);
778 if (index
> maxindex
)
783 while (radix_tree_is_internal_node(node
)) {
784 parent
= entry_to_node(node
);
785 offset
= radix_tree_descend(parent
, &node
, index
);
789 node_tag_clear(root
, parent
, tag
, offset
);
793 EXPORT_SYMBOL(radix_tree_tag_clear
);
796 * radix_tree_tag_get - get a tag on a radix tree node
797 * @root: radix tree root
799 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
803 * 0: tag not present or not set
806 * Note that the return value of this function may not be relied on, even if
807 * the RCU lock is held, unless tag modification and node deletion are excluded
810 int radix_tree_tag_get(struct radix_tree_root
*root
,
811 unsigned long index
, unsigned int tag
)
813 struct radix_tree_node
*node
, *parent
;
814 unsigned long maxindex
;
816 if (!root_tag_get(root
, tag
))
819 radix_tree_load_root(root
, &node
, &maxindex
);
820 if (index
> maxindex
)
825 while (radix_tree_is_internal_node(node
)) {
828 parent
= entry_to_node(node
);
829 offset
= radix_tree_descend(parent
, &node
, index
);
833 if (!tag_get(parent
, tag
, offset
))
835 if (node
== RADIX_TREE_RETRY
)
841 EXPORT_SYMBOL(radix_tree_tag_get
);
843 static inline void __set_iter_shift(struct radix_tree_iter
*iter
,
846 #ifdef CONFIG_RADIX_TREE_MULTIORDER
852 * radix_tree_next_chunk - find next chunk of slots for iteration
854 * @root: radix tree root
855 * @iter: iterator state
856 * @flags: RADIX_TREE_ITER_* flags and tag index
857 * Returns: pointer to chunk first slot, or NULL if iteration is over
859 void **radix_tree_next_chunk(struct radix_tree_root
*root
,
860 struct radix_tree_iter
*iter
, unsigned flags
)
862 unsigned tag
= flags
& RADIX_TREE_ITER_TAG_MASK
;
863 struct radix_tree_node
*node
, *child
;
864 unsigned long index
, offset
, maxindex
;
866 if ((flags
& RADIX_TREE_ITER_TAGGED
) && !root_tag_get(root
, tag
))
870 * Catch next_index overflow after ~0UL. iter->index never overflows
871 * during iterating; it can be zero only at the beginning.
872 * And we cannot overflow iter->next_index in a single step,
873 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
875 * This condition also used by radix_tree_next_slot() to stop
876 * contiguous iterating, and forbid swithing to the next chunk.
878 index
= iter
->next_index
;
879 if (!index
&& iter
->index
)
883 radix_tree_load_root(root
, &child
, &maxindex
);
884 if (index
> maxindex
)
889 if (!radix_tree_is_internal_node(child
)) {
890 /* Single-slot tree */
892 iter
->next_index
= maxindex
+ 1;
894 __set_iter_shift(iter
, 0);
895 return (void **)&root
->rnode
;
899 node
= entry_to_node(child
);
900 offset
= radix_tree_descend(node
, &child
, index
);
902 if ((flags
& RADIX_TREE_ITER_TAGGED
) ?
903 !tag_get(node
, tag
, offset
) : !child
) {
905 if (flags
& RADIX_TREE_ITER_CONTIG
)
908 if (flags
& RADIX_TREE_ITER_TAGGED
)
909 offset
= radix_tree_find_next_bit(
914 while (++offset
< RADIX_TREE_MAP_SIZE
) {
915 void *slot
= node
->slots
[offset
];
916 if (is_sibling_entry(node
, slot
))
921 index
&= ~node_maxindex(node
);
922 index
+= offset
<< node
->shift
;
923 /* Overflow after ~0UL */
926 if (offset
== RADIX_TREE_MAP_SIZE
)
928 child
= rcu_dereference_raw(node
->slots
[offset
]);
931 if ((child
== NULL
) || (child
== RADIX_TREE_RETRY
))
933 } while (radix_tree_is_internal_node(child
));
935 /* Update the iterator state */
936 iter
->index
= (index
&~ node_maxindex(node
)) | (offset
<< node
->shift
);
937 iter
->next_index
= (index
| node_maxindex(node
)) + 1;
938 __set_iter_shift(iter
, node
->shift
);
940 /* Construct iter->tags bit-mask from node->tags[tag] array */
941 if (flags
& RADIX_TREE_ITER_TAGGED
) {
942 unsigned tag_long
, tag_bit
;
944 tag_long
= offset
/ BITS_PER_LONG
;
945 tag_bit
= offset
% BITS_PER_LONG
;
946 iter
->tags
= node
->tags
[tag
][tag_long
] >> tag_bit
;
947 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
948 if (tag_long
< RADIX_TREE_TAG_LONGS
- 1) {
949 /* Pick tags from next element */
951 iter
->tags
|= node
->tags
[tag
][tag_long
+ 1] <<
952 (BITS_PER_LONG
- tag_bit
);
953 /* Clip chunk size, here only BITS_PER_LONG tags */
954 iter
->next_index
= index
+ BITS_PER_LONG
;
958 return node
->slots
+ offset
;
960 EXPORT_SYMBOL(radix_tree_next_chunk
);
963 * radix_tree_range_tag_if_tagged - for each item in given range set given
964 * tag if item has another tag set
965 * @root: radix tree root
966 * @first_indexp: pointer to a starting index of a range to scan
967 * @last_index: last index of a range to scan
968 * @nr_to_tag: maximum number items to tag
969 * @iftag: tag index to test
970 * @settag: tag index to set if tested tag is set
972 * This function scans range of radix tree from first_index to last_index
973 * (inclusive). For each item in the range if iftag is set, the function sets
974 * also settag. The function stops either after tagging nr_to_tag items or
975 * after reaching last_index.
977 * The tags must be set from the leaf level only and propagated back up the
978 * path to the root. We must do this so that we resolve the full path before
979 * setting any tags on intermediate nodes. If we set tags as we descend, then
980 * we can get to the leaf node and find that the index that has the iftag
981 * set is outside the range we are scanning. This reults in dangling tags and
982 * can lead to problems with later tag operations (e.g. livelocks on lookups).
984 * The function returns the number of leaves where the tag was set and sets
985 * *first_indexp to the first unscanned index.
986 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
987 * be prepared to handle that.
989 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root
*root
,
990 unsigned long *first_indexp
, unsigned long last_index
,
991 unsigned long nr_to_tag
,
992 unsigned int iftag
, unsigned int settag
)
994 struct radix_tree_node
*parent
, *node
, *child
;
995 unsigned long maxindex
;
996 unsigned long tagged
= 0;
997 unsigned long index
= *first_indexp
;
999 radix_tree_load_root(root
, &child
, &maxindex
);
1000 last_index
= min(last_index
, maxindex
);
1001 if (index
> last_index
)
1005 if (!root_tag_get(root
, iftag
)) {
1006 *first_indexp
= last_index
+ 1;
1009 if (!radix_tree_is_internal_node(child
)) {
1010 *first_indexp
= last_index
+ 1;
1011 root_tag_set(root
, settag
);
1015 node
= entry_to_node(child
);
1018 unsigned offset
= radix_tree_descend(node
, &child
, index
);
1021 if (!tag_get(node
, iftag
, offset
))
1023 /* Sibling slots never have tags set on them */
1024 if (radix_tree_is_internal_node(child
)) {
1025 node
= entry_to_node(child
);
1031 tag_set(node
, settag
, offset
);
1033 /* walk back up the path tagging interior nodes */
1036 offset
= parent
->offset
;
1037 parent
= parent
->parent
;
1040 /* stop if we find a node with the tag already set */
1041 if (tag_get(parent
, settag
, offset
))
1043 tag_set(parent
, settag
, offset
);
1046 /* Go to next entry in node */
1047 index
= ((index
>> node
->shift
) + 1) << node
->shift
;
1048 /* Overflow can happen when last_index is ~0UL... */
1049 if (index
> last_index
|| !index
)
1051 offset
= (index
>> node
->shift
) & RADIX_TREE_MAP_MASK
;
1052 while (offset
== 0) {
1054 * We've fully scanned this node. Go up. Because
1055 * last_index is guaranteed to be in the tree, what
1056 * we do below cannot wander astray.
1058 node
= node
->parent
;
1059 offset
= (index
>> node
->shift
) & RADIX_TREE_MAP_MASK
;
1061 if (is_sibling_entry(node
, node
->slots
[offset
]))
1063 if (tagged
>= nr_to_tag
)
1067 * We need not to tag the root tag if there is no tag which is set with
1068 * settag within the range from *first_indexp to last_index.
1071 root_tag_set(root
, settag
);
1072 *first_indexp
= index
;
1076 EXPORT_SYMBOL(radix_tree_range_tag_if_tagged
);
1079 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1080 * @root: radix tree root
1081 * @results: where the results of the lookup are placed
1082 * @first_index: start the lookup from this key
1083 * @max_items: place up to this many items at *results
1085 * Performs an index-ascending scan of the tree for present items. Places
1086 * them at *@results and returns the number of items which were placed at
1089 * The implementation is naive.
1091 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1092 * rcu_read_lock. In this case, rather than the returned results being
1093 * an atomic snapshot of the tree at a single point in time, the
1094 * semantics of an RCU protected gang lookup are as though multiple
1095 * radix_tree_lookups have been issued in individual locks, and results
1096 * stored in 'results'.
1099 radix_tree_gang_lookup(struct radix_tree_root
*root
, void **results
,
1100 unsigned long first_index
, unsigned int max_items
)
1102 struct radix_tree_iter iter
;
1104 unsigned int ret
= 0;
1106 if (unlikely(!max_items
))
1109 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1110 results
[ret
] = rcu_dereference_raw(*slot
);
1113 if (radix_tree_is_internal_node(results
[ret
])) {
1114 slot
= radix_tree_iter_retry(&iter
);
1117 if (++ret
== max_items
)
1123 EXPORT_SYMBOL(radix_tree_gang_lookup
);
1126 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1127 * @root: radix tree root
1128 * @results: where the results of the lookup are placed
1129 * @indices: where their indices should be placed (but usually NULL)
1130 * @first_index: start the lookup from this key
1131 * @max_items: place up to this many items at *results
1133 * Performs an index-ascending scan of the tree for present items. Places
1134 * their slots at *@results and returns the number of items which were
1135 * placed at *@results.
1137 * The implementation is naive.
1139 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1140 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1141 * protection, radix_tree_deref_slot may fail requiring a retry.
1144 radix_tree_gang_lookup_slot(struct radix_tree_root
*root
,
1145 void ***results
, unsigned long *indices
,
1146 unsigned long first_index
, unsigned int max_items
)
1148 struct radix_tree_iter iter
;
1150 unsigned int ret
= 0;
1152 if (unlikely(!max_items
))
1155 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1156 results
[ret
] = slot
;
1158 indices
[ret
] = iter
.index
;
1159 if (++ret
== max_items
)
1165 EXPORT_SYMBOL(radix_tree_gang_lookup_slot
);
1168 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1170 * @root: radix tree root
1171 * @results: where the results of the lookup are placed
1172 * @first_index: start the lookup from this key
1173 * @max_items: place up to this many items at *results
1174 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1176 * Performs an index-ascending scan of the tree for present items which
1177 * have the tag indexed by @tag set. Places the items at *@results and
1178 * returns the number of items which were placed at *@results.
1181 radix_tree_gang_lookup_tag(struct radix_tree_root
*root
, void **results
,
1182 unsigned long first_index
, unsigned int max_items
,
1185 struct radix_tree_iter iter
;
1187 unsigned int ret
= 0;
1189 if (unlikely(!max_items
))
1192 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1193 results
[ret
] = rcu_dereference_raw(*slot
);
1196 if (radix_tree_is_internal_node(results
[ret
])) {
1197 slot
= radix_tree_iter_retry(&iter
);
1200 if (++ret
== max_items
)
1206 EXPORT_SYMBOL(radix_tree_gang_lookup_tag
);
1209 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1210 * radix tree based on a tag
1211 * @root: radix tree root
1212 * @results: where the results of the lookup are placed
1213 * @first_index: start the lookup from this key
1214 * @max_items: place up to this many items at *results
1215 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1217 * Performs an index-ascending scan of the tree for present items which
1218 * have the tag indexed by @tag set. Places the slots at *@results and
1219 * returns the number of slots which were placed at *@results.
1222 radix_tree_gang_lookup_tag_slot(struct radix_tree_root
*root
, void ***results
,
1223 unsigned long first_index
, unsigned int max_items
,
1226 struct radix_tree_iter iter
;
1228 unsigned int ret
= 0;
1230 if (unlikely(!max_items
))
1233 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1234 results
[ret
] = slot
;
1235 if (++ret
== max_items
)
1241 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot
);
1243 #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1244 #include <linux/sched.h> /* for cond_resched() */
1246 struct locate_info
{
1247 unsigned long found_index
;
1252 * This linear search is at present only useful to shmem_unuse_inode().
1254 static unsigned long __locate(struct radix_tree_node
*slot
, void *item
,
1255 unsigned long index
, struct locate_info
*info
)
1260 unsigned int shift
= slot
->shift
;
1262 for (i
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1263 i
< RADIX_TREE_MAP_SIZE
;
1264 i
++, index
+= (1UL << shift
)) {
1265 struct radix_tree_node
*node
=
1266 rcu_dereference_raw(slot
->slots
[i
]);
1267 if (node
== RADIX_TREE_RETRY
)
1269 if (!radix_tree_is_internal_node(node
)) {
1271 info
->found_index
= index
;
1277 node
= entry_to_node(node
);
1278 if (is_sibling_entry(slot
, node
))
1283 } while (i
< RADIX_TREE_MAP_SIZE
);
1286 if ((index
== 0) && (i
== RADIX_TREE_MAP_SIZE
))
1292 * radix_tree_locate_item - search through radix tree for item
1293 * @root: radix tree root
1294 * @item: item to be found
1296 * Returns index where item was found, or -1 if not found.
1297 * Caller must hold no lock (since this time-consuming function needs
1298 * to be preemptible), and must check afterwards if item is still there.
1300 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1302 struct radix_tree_node
*node
;
1303 unsigned long max_index
;
1304 unsigned long cur_index
= 0;
1305 struct locate_info info
= {
1312 node
= rcu_dereference_raw(root
->rnode
);
1313 if (!radix_tree_is_internal_node(node
)) {
1316 info
.found_index
= 0;
1320 node
= entry_to_node(node
);
1322 max_index
= node_maxindex(node
);
1323 if (cur_index
> max_index
) {
1328 cur_index
= __locate(node
, item
, cur_index
, &info
);
1331 } while (!info
.stop
&& cur_index
<= max_index
);
1333 return info
.found_index
;
1336 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1340 #endif /* CONFIG_SHMEM && CONFIG_SWAP */
1343 * radix_tree_shrink - shrink radix tree to minimum height
1344 * @root radix tree root
1346 static inline bool radix_tree_shrink(struct radix_tree_root
*root
)
1348 bool shrunk
= false;
1351 struct radix_tree_node
*node
= root
->rnode
;
1352 struct radix_tree_node
*child
;
1354 if (!radix_tree_is_internal_node(node
))
1356 node
= entry_to_node(node
);
1359 * The candidate node has more than one child, or its child
1360 * is not at the leftmost slot, or the child is a multiorder
1361 * entry, we cannot shrink.
1363 if (node
->count
!= 1)
1365 child
= node
->slots
[0];
1368 if (!radix_tree_is_internal_node(child
) && node
->shift
)
1371 if (radix_tree_is_internal_node(child
))
1372 entry_to_node(child
)->parent
= NULL
;
1375 * We don't need rcu_assign_pointer(), since we are simply
1376 * moving the node from one part of the tree to another: if it
1377 * was safe to dereference the old pointer to it
1378 * (node->slots[0]), it will be safe to dereference the new
1379 * one (root->rnode) as far as dependent read barriers go.
1381 root
->rnode
= child
;
1384 * We have a dilemma here. The node's slot[0] must not be
1385 * NULLed in case there are concurrent lookups expecting to
1386 * find the item. However if this was a bottom-level node,
1387 * then it may be subject to the slot pointer being visible
1388 * to callers dereferencing it. If item corresponding to
1389 * slot[0] is subsequently deleted, these callers would expect
1390 * their slot to become empty sooner or later.
1392 * For example, lockless pagecache will look up a slot, deref
1393 * the page pointer, and if the page has 0 refcount it means it
1394 * was concurrently deleted from pagecache so try the deref
1395 * again. Fortunately there is already a requirement for logic
1396 * to retry the entire slot lookup -- the indirect pointer
1397 * problem (replacing direct root node with an indirect pointer
1398 * also results in a stale slot). So tag the slot as indirect
1399 * to force callers to retry.
1401 if (!radix_tree_is_internal_node(child
))
1402 node
->slots
[0] = RADIX_TREE_RETRY
;
1404 radix_tree_node_free(node
);
1412 * __radix_tree_delete_node - try to free node after clearing a slot
1413 * @root: radix tree root
1414 * @node: node containing @index
1416 * After clearing the slot at @index in @node from radix tree
1417 * rooted at @root, call this function to attempt freeing the
1418 * node and shrinking the tree.
1420 * Returns %true if @node was freed, %false otherwise.
1422 bool __radix_tree_delete_node(struct radix_tree_root
*root
,
1423 struct radix_tree_node
*node
)
1425 bool deleted
= false;
1428 struct radix_tree_node
*parent
;
1431 if (node
== entry_to_node(root
->rnode
))
1432 deleted
|= radix_tree_shrink(root
);
1436 parent
= node
->parent
;
1438 parent
->slots
[node
->offset
] = NULL
;
1441 root_tag_clear_all(root
);
1445 radix_tree_node_free(node
);
1454 static inline void delete_sibling_entries(struct radix_tree_node
*node
,
1455 void *ptr
, unsigned offset
)
1457 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1459 for (i
= 1; offset
+ i
< RADIX_TREE_MAP_SIZE
; i
++) {
1460 if (node
->slots
[offset
+ i
] != ptr
)
1462 node
->slots
[offset
+ i
] = NULL
;
1469 * radix_tree_delete_item - delete an item from a radix tree
1470 * @root: radix tree root
1472 * @item: expected item
1474 * Remove @item at @index from the radix tree rooted at @root.
1476 * Returns the address of the deleted item, or NULL if it was not present
1477 * or the entry at the given @index was not @item.
1479 void *radix_tree_delete_item(struct radix_tree_root
*root
,
1480 unsigned long index
, void *item
)
1482 struct radix_tree_node
*node
;
1483 unsigned int offset
;
1488 entry
= __radix_tree_lookup(root
, index
, &node
, &slot
);
1492 if (item
&& entry
!= item
)
1496 root_tag_clear_all(root
);
1501 offset
= get_slot_offset(node
, slot
);
1503 /* Clear all tags associated with the item to be deleted. */
1504 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1505 node_tag_clear(root
, node
, tag
, offset
);
1507 delete_sibling_entries(node
, node_to_entry(slot
), offset
);
1508 node
->slots
[offset
] = NULL
;
1511 __radix_tree_delete_node(root
, node
);
1515 EXPORT_SYMBOL(radix_tree_delete_item
);
1518 * radix_tree_delete - delete an item from a radix tree
1519 * @root: radix tree root
1522 * Remove the item at @index from the radix tree rooted at @root.
1524 * Returns the address of the deleted item, or NULL if it was not present.
1526 void *radix_tree_delete(struct radix_tree_root
*root
, unsigned long index
)
1528 return radix_tree_delete_item(root
, index
, NULL
);
1530 EXPORT_SYMBOL(radix_tree_delete
);
1532 struct radix_tree_node
*radix_tree_replace_clear_tags(
1533 struct radix_tree_root
*root
,
1534 unsigned long index
, void *entry
)
1536 struct radix_tree_node
*node
;
1539 __radix_tree_lookup(root
, index
, &node
, &slot
);
1542 unsigned int tag
, offset
= get_slot_offset(node
, slot
);
1543 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1544 node_tag_clear(root
, node
, tag
, offset
);
1546 /* Clear root node tags */
1547 root
->gfp_mask
&= __GFP_BITS_MASK
;
1550 radix_tree_replace_slot(slot
, entry
);
1555 * radix_tree_tagged - test whether any items in the tree are tagged
1556 * @root: radix tree root
1559 int radix_tree_tagged(struct radix_tree_root
*root
, unsigned int tag
)
1561 return root_tag_get(root
, tag
);
1563 EXPORT_SYMBOL(radix_tree_tagged
);
1566 radix_tree_node_ctor(void *arg
)
1568 struct radix_tree_node
*node
= arg
;
1570 memset(node
, 0, sizeof(*node
));
1571 INIT_LIST_HEAD(&node
->private_list
);
1574 static int radix_tree_callback(struct notifier_block
*nfb
,
1575 unsigned long action
, void *hcpu
)
1577 int cpu
= (long)hcpu
;
1578 struct radix_tree_preload
*rtp
;
1579 struct radix_tree_node
*node
;
1581 /* Free per-cpu pool of preloaded nodes */
1582 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
1583 rtp
= &per_cpu(radix_tree_preloads
, cpu
);
1586 rtp
->nodes
= node
->private_data
;
1587 kmem_cache_free(radix_tree_node_cachep
, node
);
1594 void __init
radix_tree_init(void)
1596 radix_tree_node_cachep
= kmem_cache_create("radix_tree_node",
1597 sizeof(struct radix_tree_node
), 0,
1598 SLAB_PANIC
| SLAB_RECLAIM_ACCOUNT
,
1599 radix_tree_node_ctor
);
1600 hotcpu_notifier(radix_tree_callback
, 0);