diff options
Diffstat (limited to 'lib/radix-tree.c')
| -rw-r--r-- | lib/radix-tree.c | 1111 |
1 files changed, 590 insertions, 521 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 5086bb962b4..3291a8e3749 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -3,6 +3,7 @@ * Portions Copyright (C) 2001 Christoph Hellwig * Copyright (C) 2005 SGI, Christoph Lameter * Copyright (C) 2006 Nick Piggin + * Copyright (C) 2012 Konstantin Khlebnikov * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as @@ -22,46 +23,19 @@ #include <linux/errno.h> #include <linux/init.h> #include <linux/kernel.h> -#include <linux/module.h> +#include <linux/export.h> #include <linux/radix-tree.h> #include <linux/percpu.h> #include <linux/slab.h> +#include <linux/kmemleak.h> #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/string.h> #include <linux/bitops.h> #include <linux/rcupdate.h> +#include <linux/hardirq.h> /* in_interrupt() */ -#ifdef __KERNEL__ -#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) -#else -#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ -#endif - -#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) -#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) - -#define RADIX_TREE_TAG_LONGS \ - ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) - -struct radix_tree_node { - unsigned int height; /* Height from the bottom */ - unsigned int count; - struct rcu_head rcu_head; - void __rcu *slots[RADIX_TREE_MAP_SIZE]; - unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; -}; - -struct radix_tree_path { - struct radix_tree_node *node; - int offset; -}; - -#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) -#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ - RADIX_TREE_MAP_SHIFT)) - /* * The height_to_maxindex array needs to be one deeper than the maximum * path as height 0 holds only 1 entry. @@ -74,11 +48,24 @@ static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; static struct kmem_cache *radix_tree_node_cachep; /* + * The radix tree is variable-height, so an insert operation not only has + * to build the branch to its corresponding item, it also has to build the + * branch to existing items if the size has to be increased (by + * radix_tree_extend). + * + * The worst case is a zero height tree with just a single item at index 0, + * and then inserting an item at index ULONG_MAX. This requires 2 new branches + * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. + * Hence: + */ +#define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) + +/* * Per-cpu pool of preloaded nodes */ struct radix_tree_preload { int nr; - struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; + struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE]; }; static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; @@ -148,6 +135,43 @@ static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) } return 0; } + +/** + * radix_tree_find_next_bit - find the next set bit in a memory region + * + * @addr: The address to base the search on + * @size: The bitmap size in bits + * @offset: The bitnumber to start searching at + * + * Unrollable variant of find_next_bit() for constant size arrays. + * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero. + * Returns next bit offset, or size if nothing found. + */ +static __always_inline unsigned long +radix_tree_find_next_bit(const unsigned long *addr, + unsigned long size, unsigned long offset) +{ + if (!__builtin_constant_p(size)) + return find_next_bit(addr, size, offset); + + if (offset < size) { + unsigned long tmp; + + addr += offset / BITS_PER_LONG; + tmp = *addr >> (offset % BITS_PER_LONG); + if (tmp) + return __ffs(tmp) + offset; + offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1); + while (offset < size) { + tmp = *++addr; + if (tmp) + return __ffs(tmp) + offset; + offset += BITS_PER_LONG; + } + } + return size; +} + /* * This assumes that the caller has performed appropriate preallocation, and * that the caller has pinned this thread of control to the current CPU. @@ -158,7 +182,12 @@ radix_tree_node_alloc(struct radix_tree_root *root) struct radix_tree_node *ret = NULL; gfp_t gfp_mask = root_gfp_mask(root); - if (!(gfp_mask & __GFP_WAIT)) { + /* + * Preload code isn't irq safe and it doesn't make sence to use + * preloading in the interrupt anyway as all the allocations have to + * be atomic. So just do normal allocation when in interrupt. + */ + if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) { struct radix_tree_preload *rtp; /* @@ -166,12 +195,17 @@ radix_tree_node_alloc(struct radix_tree_root *root) * succeed in getting a node here (and never reach * kmem_cache_alloc) */ - rtp = &__get_cpu_var(radix_tree_preloads); + rtp = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; rtp->nodes[rtp->nr - 1] = NULL; rtp->nr--; } + /* + * Update the allocation stack trace as this is more useful + * for debugging. + */ + kmemleak_update_trace(ret); } if (ret == NULL) ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); @@ -215,21 +249,21 @@ radix_tree_node_free(struct radix_tree_node *node) * To make use of this facility, the radix tree must be initialised without * __GFP_WAIT being passed to INIT_RADIX_TREE(). */ -int radix_tree_preload(gfp_t gfp_mask) +static int __radix_tree_preload(gfp_t gfp_mask) { struct radix_tree_preload *rtp; struct radix_tree_node *node; int ret = -ENOMEM; preempt_disable(); - rtp = &__get_cpu_var(radix_tree_preloads); + rtp = this_cpu_ptr(&radix_tree_preloads); while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { preempt_enable(); node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); if (node == NULL) goto out; preempt_disable(); - rtp = &__get_cpu_var(radix_tree_preloads); + rtp = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr < ARRAY_SIZE(rtp->nodes)) rtp->nodes[rtp->nr++] = node; else @@ -239,9 +273,40 @@ int radix_tree_preload(gfp_t gfp_mask) out: return ret; } + +/* + * Load up this CPU's radix_tree_node buffer with sufficient objects to + * ensure that the addition of a single element in the tree cannot fail. On + * success, return zero, with preemption disabled. On error, return -ENOMEM + * with preemption not disabled. + * + * To make use of this facility, the radix tree must be initialised without + * __GFP_WAIT being passed to INIT_RADIX_TREE(). + */ +int radix_tree_preload(gfp_t gfp_mask) +{ + /* Warn on non-sensical use... */ + WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT)); + return __radix_tree_preload(gfp_mask); +} EXPORT_SYMBOL(radix_tree_preload); /* + * The same as above function, except we don't guarantee preloading happens. + * We do it, if we decide it helps. On success, return zero with preemption + * disabled. On error, return -ENOMEM with preemption not disabled. + */ +int radix_tree_maybe_preload(gfp_t gfp_mask) +{ + if (gfp_mask & __GFP_WAIT) + return __radix_tree_preload(gfp_mask); + /* Preloading doesn't help anything with this gfp mask, skip it */ + preempt_disable(); + return 0; +} +EXPORT_SYMBOL(radix_tree_maybe_preload); + +/* * Return the maximum key which can be store into a * radix tree with height HEIGHT. */ @@ -256,6 +321,7 @@ static inline unsigned long radix_tree_maxindex(unsigned int height) static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) { struct radix_tree_node *node; + struct radix_tree_node *slot; unsigned int height; int tag; @@ -274,18 +340,24 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; - /* Increase the height. */ - node->slots[0] = indirect_to_ptr(root->rnode); - /* Propagate the aggregated tag info into the new root */ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { if (root_tag_get(root, tag)) tag_set(node, tag, 0); } + /* Increase the height. */ newheight = root->height+1; - node->height = newheight; + BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK); + node->path = newheight; node->count = 1; + node->parent = NULL; + slot = root->rnode; + if (newheight > 1) { + slot = indirect_to_ptr(slot); + slot->parent = node; + } + node->slots[0] = slot; node = ptr_to_indirect(node); rcu_assign_pointer(root->rnode, node); root->height = newheight; @@ -295,23 +367,28 @@ out: } /** - * radix_tree_insert - insert into a radix tree + * __radix_tree_create - create a slot in a radix tree * @root: radix tree root * @index: index key - * @item: item to insert + * @nodep: returns node + * @slotp: returns slot * - * Insert an item into the radix tree at position @index. + * 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_insert(struct radix_tree_root *root, - unsigned long index, void *item) +int __radix_tree_create(struct radix_tree_root *root, unsigned long index, + struct radix_tree_node **nodep, void ***slotp) { struct radix_tree_node *node = NULL, *slot; - unsigned int height, shift; - int offset; + unsigned int height, shift, offset; int error; - BUG_ON(radix_tree_is_indirect_ptr(item)); - /* Make sure the tree is high enough. */ if (index > radix_tree_maxindex(root->height)) { error = radix_tree_extend(root, index); @@ -330,10 +407,12 @@ int radix_tree_insert(struct radix_tree_root *root, /* Have to add a child node. */ if (!(slot = radix_tree_node_alloc(root))) return -ENOMEM; - slot->height = height; + slot->path = height; + slot->parent = node; if (node) { rcu_assign_pointer(node->slots[offset], slot); node->count++; + slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT; } else rcu_assign_pointer(root->rnode, ptr_to_indirect(slot)); } @@ -346,16 +425,42 @@ int radix_tree_insert(struct radix_tree_root *root, height--; } - if (slot != NULL) + if (nodep) + *nodep = node; + if (slotp) + *slotp = node ? node->slots + offset : (void **)&root->rnode; + return 0; +} + +/** + * radix_tree_insert - insert into a radix tree + * @root: radix tree root + * @index: index key + * @item: item to insert + * + * Insert an item into the radix tree at position @index. + */ +int radix_tree_insert(struct radix_tree_root *root, + unsigned long index, void *item) +{ + struct radix_tree_node *node; + void **slot; + int error; + + BUG_ON(radix_tree_is_indirect_ptr(item)); + + error = __radix_tree_create(root, index, &node, &slot); + if (error) + return error; + if (*slot != NULL) return -EEXIST; + rcu_assign_pointer(*slot, item); if (node) { node->count++; - rcu_assign_pointer(node->slots[offset], item); - BUG_ON(tag_get(node, 0, offset)); - BUG_ON(tag_get(node, 1, offset)); + BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK)); + BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK)); } else { - rcu_assign_pointer(root->rnode, item); BUG_ON(root_tag_get(root, 0)); BUG_ON(root_tag_get(root, 1)); } @@ -364,15 +469,26 @@ int radix_tree_insert(struct radix_tree_root *root, } EXPORT_SYMBOL(radix_tree_insert); -/* - * is_slot == 1 : search for the slot. - * is_slot == 0 : search for the node. +/** + * __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. */ -static void *radix_tree_lookup_element(struct radix_tree_root *root, - unsigned long index, int is_slot) +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 int height, shift; - struct radix_tree_node *node, **slot; + void **slot; node = rcu_dereference_raw(root->rnode); if (node == NULL) @@ -381,19 +497,24 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, if (!radix_tree_is_indirect_ptr(node)) { if (index > 0) return NULL; - return is_slot ? (void *)&root->rnode : node; + + if (nodep) + *nodep = NULL; + if (slotp) + *slotp = (void **)&root->rnode; + return node; } node = indirect_to_ptr(node); - height = node->height; + height = node->path & RADIX_TREE_HEIGHT_MASK; if (index > radix_tree_maxindex(height)) return NULL; shift = (height-1) * RADIX_TREE_MAP_SHIFT; do { - slot = (struct radix_tree_node **) - (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); + parent = node; + slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK); node = rcu_dereference_raw(*slot); if (node == NULL) return NULL; @@ -402,7 +523,11 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, height--; } while (height > 0); - return is_slot ? (void *)slot : indirect_to_ptr(node); + if (nodep) + *nodep = parent; + if (slotp) + *slotp = slot; + return node; } /** @@ -420,7 +545,11 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, */ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { - return (void **)radix_tree_lookup_element(root, index, 1); + void **slot; + + if (!__radix_tree_lookup(root, index, NULL, &slot)) + return NULL; + return slot; } EXPORT_SYMBOL(radix_tree_lookup_slot); @@ -438,7 +567,7 @@ EXPORT_SYMBOL(radix_tree_lookup_slot); */ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) { - return radix_tree_lookup_element(root, index, 0); + return __radix_tree_lookup(root, index, NULL, NULL); } EXPORT_SYMBOL(radix_tree_lookup); @@ -504,47 +633,41 @@ EXPORT_SYMBOL(radix_tree_tag_set); void *radix_tree_tag_clear(struct radix_tree_root *root, unsigned long index, unsigned int tag) { - /* - * The radix tree path needs to be one longer than the maximum path - * since the "list" is null terminated. - */ - struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; + struct radix_tree_node *node = NULL; struct radix_tree_node *slot = NULL; unsigned int height, shift; + int uninitialized_var(offset); height = root->height; if (index > radix_tree_maxindex(height)) goto out; - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; - pathp->node = NULL; + shift = height * RADIX_TREE_MAP_SHIFT; slot = indirect_to_ptr(root->rnode); - while (height > 0) { - int offset; - + while (shift) { if (slot == NULL) goto out; + shift -= RADIX_TREE_MAP_SHIFT; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp[1].offset = offset; - pathp[1].node = slot; + node = slot; slot = slot->slots[offset]; - pathp++; - shift -= RADIX_TREE_MAP_SHIFT; - height--; } if (slot == NULL) goto out; - while (pathp->node) { - if (!tag_get(pathp->node, tag, pathp->offset)) + while (node) { + if (!tag_get(node, tag, offset)) goto out; - tag_clear(pathp->node, tag, pathp->offset); - if (any_tag_set(pathp->node, tag)) + tag_clear(node, tag, offset); + if (any_tag_set(node, tag)) goto out; - pathp--; + + index >>= RADIX_TREE_MAP_SHIFT; + offset = index & RADIX_TREE_MAP_MASK; + node = node->parent; } /* clear the root's tag bit */ @@ -576,7 +699,6 @@ int radix_tree_tag_get(struct radix_tree_root *root, { unsigned int height, shift; struct radix_tree_node *node; - int saw_unset_tag = 0; /* check the root's tag bit */ if (!root_tag_get(root, tag)) @@ -590,7 +712,7 @@ int radix_tree_tag_get(struct radix_tree_root *root, return (index == 0); node = indirect_to_ptr(node); - height = node->height; + height = node->path & RADIX_TREE_HEIGHT_MASK; if (index > radix_tree_maxindex(height)) return 0; @@ -603,15 +725,10 @@ int radix_tree_tag_get(struct radix_tree_root *root, return 0; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - - /* - * This is just a debug check. Later, we can bale as soon as - * we see an unset tag. - */ if (!tag_get(node, tag, offset)) - saw_unset_tag = 1; + return 0; if (height == 1) - return !!tag_get(node, tag, offset); + return 1; node = rcu_dereference_raw(node->slots[offset]); shift -= RADIX_TREE_MAP_SHIFT; height--; @@ -620,6 +737,123 @@ int radix_tree_tag_get(struct radix_tree_root *root, EXPORT_SYMBOL(radix_tree_tag_get); /** + * radix_tree_next_chunk - find next chunk of slots for iteration + * + * @root: radix tree root + * @iter: iterator state + * @flags: RADIX_TREE_ITER_* flags and tag index + * Returns: pointer to chunk first slot, or NULL if iteration is over + */ +void **radix_tree_next_chunk(struct radix_tree_root *root, + struct radix_tree_iter *iter, unsigned flags) +{ + unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK; + struct radix_tree_node *rnode, *node; + unsigned long index, offset, height; + + 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; + + rnode = rcu_dereference_raw(root->rnode); + if (radix_tree_is_indirect_ptr(rnode)) { + rnode = indirect_to_ptr(rnode); + } else if (rnode && !index) { + /* Single-slot tree */ + iter->index = 0; + iter->next_index = 1; + iter->tags = 1; + return (void **)&root->rnode; + } else + return NULL; + +restart: + height = rnode->path & RADIX_TREE_HEIGHT_MASK; + shift = (height - 1) * RADIX_TREE_MAP_SHIFT; + offset = index >> shift; + + /* Index outside of the tree */ + if (offset >= RADIX_TREE_MAP_SIZE) + return NULL; + + node = rnode; + while (1) { + if ((flags & RADIX_TREE_ITER_TAGGED) ? + !test_bit(offset, node->tags[tag]) : + !node->slots[offset]) { + /* Hole detected */ + if (flags & RADIX_TREE_ITER_CONTIG) + return NULL; + + if (flags & RADIX_TREE_ITER_TAGGED) + offset = radix_tree_find_next_bit( + node->tags[tag], + RADIX_TREE_MAP_SIZE, + offset + 1); + else + while (++offset < RADIX_TREE_MAP_SIZE) { + if (node->slots[offset]) + break; + } + index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1); + index += offset << shift; + /* Overflow after ~0UL */ + if (!index) + return NULL; + if (offset == RADIX_TREE_MAP_SIZE) + goto restart; + } + + /* This is leaf-node */ + if (!shift) + break; + + node = rcu_dereference_raw(node->slots[offset]); + if (node == NULL) + goto restart; + shift -= RADIX_TREE_MAP_SHIFT; + offset = (index >> shift) & RADIX_TREE_MAP_MASK; + } + + /* Update the iterator state */ + iter->index = index; + iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1; + + /* Construct iter->tags bit-mask from node->tags[tag] array */ + if (flags & RADIX_TREE_ITER_TAGGED) { + unsigned tag_long, tag_bit; + + tag_long = offset / BITS_PER_LONG; + tag_bit = offset % BITS_PER_LONG; + iter->tags = node->tags[tag][tag_long] >> tag_bit; + /* This never happens if RADIX_TREE_TAG_LONGS == 1 */ + if (tag_long < RADIX_TREE_TAG_LONGS - 1) { + /* Pick tags from next element */ + if (tag_bit) + iter->tags |= node->tags[tag][tag_long + 1] << + (BITS_PER_LONG - tag_bit); + /* Clip chunk size, here only BITS_PER_LONG tags */ + iter->next_index = index + BITS_PER_LONG; + } + } + + return node->slots + offset; +} +EXPORT_SYMBOL(radix_tree_next_chunk); + +/** * radix_tree_range_tag_if_tagged - for each item in given range set given * tag if item has another tag set * @root: radix tree root @@ -652,8 +886,7 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, unsigned int iftag, unsigned int settag) { unsigned int height = root->height; - struct radix_tree_path path[height]; - struct radix_tree_path *pathp = path; + struct radix_tree_node *node = NULL; struct radix_tree_node *slot; unsigned int shift; unsigned long tagged = 0; @@ -677,14 +910,8 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = indirect_to_ptr(root->rnode); - /* - * we fill the path from (root->height - 2) to 0, leaving the index at - * (root->height - 1) as a terminator. Zero the node in the terminator - * so that we can use this to end walk loops back up the path. - */ - path[height - 1].node = NULL; - for (;;) { + unsigned long upindex; int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; @@ -692,12 +919,10 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, goto next; if (!tag_get(slot, iftag, offset)) goto next; - if (height > 1) { + if (shift) { /* Go down one level */ - height--; shift -= RADIX_TREE_MAP_SHIFT; - path[height - 1].node = slot; - path[height - 1].offset = offset; + node = slot; slot = slot->slots[offset]; continue; } @@ -707,15 +932,27 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, tag_set(slot, settag, offset); /* walk back up the path tagging interior nodes */ - pathp = &path[0]; - while (pathp->node) { + upindex = index; + while (node) { + upindex >>= RADIX_TREE_MAP_SHIFT; + offset = upindex & RADIX_TREE_MAP_MASK; + /* stop if we find a node with the tag already set */ - if (tag_get(pathp->node, settag, pathp->offset)) + if (tag_get(node, settag, offset)) break; - tag_set(pathp->node, settag, pathp->offset); - pathp++; + tag_set(node, settag, offset); + node = node->parent; } + /* + * Small optimization: now clear that node pointer. + * Since all of this slot's ancestors now have the tag set + * from setting it above, we have no further need to walk + * back up the tree setting tags, until we update slot to + * point to another radix_tree_node. + */ + node = NULL; + next: /* Go to next item at level determined by 'shift' */ index = ((index >> shift) + 1) << shift; @@ -730,144 +967,22 @@ next: * last_index is guaranteed to be in the tree, what * we do below cannot wander astray. */ - slot = path[height - 1].node; - height++; + slot = slot->parent; shift += RADIX_TREE_MAP_SHIFT; } } /* - * The iftag must have been set somewhere because otherwise - * we would return immediated at the beginning of the function + * 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. */ - root_tag_set(root, settag); + if (tagged > 0) + root_tag_set(root, settag); *first_indexp = index; return tagged; } EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); - -/** - * radix_tree_next_hole - find the next hole (not-present entry) - * @root: tree root - * @index: index key - * @max_scan: maximum range to search - * - * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest - * indexed hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'return - index >= max_scan' - * will be true). In rare cases of index wrap-around, 0 will be returned. - * - * radix_tree_next_hole may be called under rcu_read_lock. However, like - * radix_tree_gang_lookup, this will not atomically search a snapshot of - * the tree at a single point in time. For example, if a hole is created - * at index 5, then subsequently a hole is created at index 10, - * radix_tree_next_hole covering both indexes may return 10 if called - * under rcu_read_lock. - */ -unsigned long radix_tree_next_hole(struct radix_tree_root *root, - unsigned long index, unsigned long max_scan) -{ - unsigned long i; - - for (i = 0; i < max_scan; i++) { - if (!radix_tree_lookup(root, index)) - break; - index++; - if (index == 0) - break; - } - - return index; -} -EXPORT_SYMBOL(radix_tree_next_hole); - -/** - * radix_tree_prev_hole - find the prev hole (not-present entry) - * @root: tree root - * @index: index key - * @max_scan: maximum range to search - * - * Search backwards in the range [max(index-max_scan+1, 0), index] - * for the first hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'index - return >= max_scan' - * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. - * - * radix_tree_next_hole may be called under rcu_read_lock. However, like - * radix_tree_gang_lookup, this will not atomically search a snapshot of - * the tree at a single point in time. For example, if a hole is created - * at index 10, then subsequently a hole is created at index 5, - * radix_tree_prev_hole covering both indexes may return 5 if called under - * rcu_read_lock. - */ -unsigned long radix_tree_prev_hole(struct radix_tree_root *root, - unsigned long index, unsigned long max_scan) -{ - unsigned long i; - - for (i = 0; i < max_scan; i++) { - if (!radix_tree_lookup(root, index)) - break; - index--; - if (index == ULONG_MAX) - break; - } - - return index; -} -EXPORT_SYMBOL(radix_tree_prev_hole); - -static unsigned int -__lookup(struct radix_tree_node *slot, void ***results, unsigned long index, - unsigned int max_items, unsigned long *next_index) -{ - unsigned int nr_found = 0; - unsigned int shift, height; - unsigned long i; - - height = slot->height; - if (height == 0) - goto out; - shift = (height-1) * RADIX_TREE_MAP_SHIFT; - - for ( ; height > 1; height--) { - i = (index >> shift) & RADIX_TREE_MAP_MASK; - for (;;) { - if (slot->slots[i] != NULL) - break; - index &= ~((1UL << shift) - 1); - index += 1UL << shift; - if (index == 0) - goto out; /* 32-bit wraparound */ - i++; - if (i == RADIX_TREE_MAP_SIZE) - goto out; - } - - shift -= RADIX_TREE_MAP_SHIFT; - slot = rcu_dereference_raw(slot->slots[i]); - if (slot == NULL) - goto out; - } - - /* Bottom level: grab some items */ - for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { - index++; - if (slot->slots[i]) { - results[nr_found++] = &(slot->slots[i]); - if (nr_found == max_items) - goto out; - } - } -out: - *next_index = index; - return nr_found; -} - /** * radix_tree_gang_lookup - perform multiple lookup on a radix tree * @root: radix tree root @@ -891,48 +1006,19 @@ unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items) { - unsigned long max_index; - struct radix_tree_node *node; - unsigned long cur_index = first_index; - unsigned int ret; + struct radix_tree_iter iter; + void **slot; + unsigned int ret = 0; - node = rcu_dereference_raw(root->rnode); - if (!node) + if (unlikely(!max_items)) return 0; - if (!radix_tree_is_indirect_ptr(node)) { - if (first_index > 0) - return 0; - results[0] = node; - return 1; - } - node = indirect_to_ptr(node); - - max_index = radix_tree_maxindex(node->height); - - ret = 0; - while (ret < max_items) { - unsigned int nr_found, slots_found, i; - unsigned long next_index; /* Index of next search */ - - if (cur_index > max_index) - break; - slots_found = __lookup(node, (void ***)results + ret, cur_index, - max_items - ret, &next_index); - nr_found = 0; - for (i = 0; i < slots_found; i++) { - struct radix_tree_node *slot; - slot = *(((void ***)results)[ret + i]); - if (!slot) - continue; - results[ret + nr_found] = - indirect_to_ptr(rcu_dereference_raw(slot)); - nr_found++; - } - ret += nr_found; - if (next_index == 0) + radix_tree_for_each_slot(slot, root, &iter, first_index) { + results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot)); + if (!results[ret]) + continue; + if (++ret == max_items) break; - cur_index = next_index; } return ret; @@ -943,6 +1029,7 @@ 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 * @@ -957,112 +1044,29 @@ EXPORT_SYMBOL(radix_tree_gang_lookup); * protection, radix_tree_deref_slot may fail requiring a retry. */ unsigned int -radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, +radix_tree_gang_lookup_slot(struct radix_tree_root *root, + void ***results, unsigned long *indices, unsigned long first_index, unsigned int max_items) { - unsigned long max_index; - struct radix_tree_node *node; - unsigned long cur_index = first_index; - unsigned int ret; + struct radix_tree_iter iter; + void **slot; + unsigned int ret = 0; - node = rcu_dereference_raw(root->rnode); - if (!node) + if (unlikely(!max_items)) return 0; - if (!radix_tree_is_indirect_ptr(node)) { - if (first_index > 0) - return 0; - results[0] = (void **)&root->rnode; - return 1; - } - node = indirect_to_ptr(node); - - max_index = radix_tree_maxindex(node->height); - - ret = 0; - while (ret < max_items) { - unsigned int slots_found; - unsigned long next_index; /* Index of next search */ - - if (cur_index > max_index) - break; - slots_found = __lookup(node, results + ret, cur_index, - max_items - ret, &next_index); - ret += slots_found; - if (next_index == 0) + radix_tree_for_each_slot(slot, root, &iter, first_index) { + results[ret] = slot; + if (indices) + indices[ret] = iter.index; + if (++ret == max_items) break; - cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_slot); -/* - * FIXME: the two tag_get()s here should use find_next_bit() instead of - * open-coding the search. - */ -static unsigned int -__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, - unsigned int max_items, unsigned long *next_index, unsigned int tag) -{ - unsigned int nr_found = 0; - unsigned int shift, height; - - height = slot->height; - if (height == 0) - goto out; - shift = (height-1) * RADIX_TREE_MAP_SHIFT; - - while (height > 0) { - unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; - - for (;;) { - if (tag_get(slot, tag, i)) - break; - index &= ~((1UL << shift) - 1); - index += 1UL << shift; - if (index == 0) - goto out; /* 32-bit wraparound */ - i++; - if (i == RADIX_TREE_MAP_SIZE) - goto out; - } - height--; - if (height == 0) { /* Bottom level: grab some items */ - unsigned long j = index & RADIX_TREE_MAP_MASK; - - for ( ; j < RADIX_TREE_MAP_SIZE; j++) { - index++; - if (!tag_get(slot, tag, j)) - continue; - /* - * Even though the tag was found set, we need to - * recheck that we have a non-NULL node, because - * if this lookup is lockless, it may have been - * subsequently deleted. - * - * Similar care must be taken in any place that - * lookup ->slots[x] without a lock (ie. can't - * rely on its value remaining the same). - */ - if (slot->slots[j]) { - results[nr_found++] = &(slot->slots[j]); - if (nr_found == max_items) - goto out; - } - } - } - shift -= RADIX_TREE_MAP_SHIFT; - slot = rcu_dereference_raw(slot->slots[i]); - if (slot == NULL) - break; - } -out: - *next_index = index; - return nr_found; -} - /** * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree * based on a tag @@ -1081,52 +1085,19 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items, unsigned int tag) { - struct radix_tree_node *node; - unsigned long max_index; - unsigned long cur_index = first_index; - unsigned int ret; - - /* check the root's tag bit */ - if (!root_tag_get(root, tag)) - return 0; + struct radix_tree_iter iter; + void **slot; + unsigned int ret = 0; - node = rcu_dereference_raw(root->rnode); - if (!node) + if (unlikely(!max_items)) return 0; - if (!radix_tree_is_indirect_ptr(node)) { - if (first_index > 0) - return 0; - results[0] = node; - return 1; - } - node = indirect_to_ptr(node); - - max_index = radix_tree_maxindex(node->height); - - ret = 0; - while (ret < max_items) { - unsigned int nr_found, slots_found, i; - unsigned long next_index; /* Index of next search */ - - if (cur_index > max_index) - break; - slots_found = __lookup_tag(node, (void ***)results + ret, - cur_index, max_items - ret, &next_index, tag); - nr_found = 0; - for (i = 0; i < slots_found; i++) { - struct radix_tree_node *slot; - slot = *(((void ***)results)[ret + i]); - if (!slot) - continue; - results[ret + nr_found] = - indirect_to_ptr(rcu_dereference_raw(slot)); - nr_found++; - } - ret += nr_found; - if (next_index == 0) + radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { + results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot)); + if (!results[ret]) + continue; + if (++ret == max_items) break; - cur_index = next_index; } return ret; @@ -1151,48 +1122,118 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, unsigned long first_index, unsigned int max_items, unsigned int tag) { - struct radix_tree_node *node; - unsigned long max_index; - unsigned long cur_index = first_index; - unsigned int ret; + struct radix_tree_iter iter; + void **slot; + unsigned int ret = 0; - /* check the root's tag bit */ - if (!root_tag_get(root, tag)) + if (unlikely(!max_items)) return 0; - node = rcu_dereference_raw(root->rnode); - if (!node) - return 0; + radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { + results[ret] = slot; + if (++ret == max_items) + break; + } - if (!radix_tree_is_indirect_ptr(node)) { - if (first_index > 0) - return 0; - results[0] = (void **)&root->rnode; - return 1; + return ret; +} +EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); + +#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) +#include <linux/sched.h> /* for cond_resched() */ + +/* + * This linear search is at present only useful to shmem_unuse_inode(). + */ +static unsigned long __locate(struct radix_tree_node *slot, void *item, + unsigned long index, unsigned long *found_index) +{ + unsigned int shift, height; + unsigned long i; + + height = slot->path & RADIX_TREE_HEIGHT_MASK; + shift = (height-1) * RADIX_TREE_MAP_SHIFT; + + for ( ; height > 1; height--) { + i = (index >> shift) & RADIX_TREE_MAP_MASK; + for (;;) { + if (slot->slots[i] != NULL) + break; + index &= ~((1UL << shift) - 1); + index += 1UL << shift; + if (index == 0) + goto out; /* 32-bit wraparound */ + i++; + if (i == RADIX_TREE_MAP_SIZE) + goto out; + } + + shift -= RADIX_TREE_MAP_SHIFT; + slot = rcu_dereference_raw(slot->slots[i]); + if (slot == NULL) + goto out; } - node = indirect_to_ptr(node); - max_index = radix_tree_maxindex(node->height); + /* Bottom level: check items */ + for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { + if (slot->slots[i] == item) { + *found_index = index + i; + index = 0; + goto out; + } + } + index += RADIX_TREE_MAP_SIZE; +out: + return index; +} - ret = 0; - while (ret < max_items) { - unsigned int slots_found; - unsigned long next_index; /* Index of next search */ +/** + * radix_tree_locate_item - search through radix tree for item + * @root: radix tree root + * @item: item to be found + * + * Returns index where item was found, or -1 if not found. + * Caller must hold no lock (since this time-consuming function needs + * to be preemptible), and must check afterwards if item is still there. + */ +unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) +{ + struct radix_tree_node *node; + unsigned long max_index; + unsigned long cur_index = 0; + unsigned long found_index = -1; - if (cur_index > max_index) + do { + rcu_read_lock(); + node = rcu_dereference_raw(root->rnode); + if (!radix_tree_is_indirect_ptr(node)) { + rcu_read_unlock(); + if (node == item) + found_index = 0; break; - slots_found = __lookup_tag(node, results + ret, - cur_index, max_items - ret, &next_index, tag); - ret += slots_found; - if (next_index == 0) + } + + node = indirect_to_ptr(node); + max_index = radix_tree_maxindex(node->path & + RADIX_TREE_HEIGHT_MASK); + if (cur_index > max_index) { + rcu_read_unlock(); break; - cur_index = next_index; - } + } - return ret; -} -EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); + cur_index = __locate(node, item, cur_index, &found_index); + rcu_read_unlock(); + cond_resched(); + } while (cur_index != 0 && cur_index <= max_index); + return found_index; +} +#else +unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) +{ + return -1; +} +#endif /* CONFIG_SHMEM && CONFIG_SWAP */ /** * radix_tree_shrink - shrink height of a radix tree to minimal @@ -1203,7 +1244,7 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) /* try to shrink tree height */ while (root->height > 0) { struct radix_tree_node *to_free = root->rnode; - void *newptr; + struct radix_tree_node *slot; BUG_ON(!radix_tree_is_indirect_ptr(to_free)); to_free = indirect_to_ptr(to_free); @@ -1224,10 +1265,12 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) * (to_free->slots[0]), it will be safe to dereference the new * one (root->rnode) as far as dependent read barriers go. */ - newptr = to_free->slots[0]; - if (root->height > 1) - newptr = ptr_to_indirect(newptr); - root->rnode = newptr; + slot = to_free->slots[0]; + if (root->height > 1) { + slot->parent = NULL; + slot = ptr_to_indirect(slot); + } + root->rnode = slot; root->height--; /* @@ -1257,97 +1300,120 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) } /** - * radix_tree_delete - delete an item from a radix tree + * __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 == indirect_to_ptr(root->rnode)) { + radix_tree_shrink(root); + if (root->height == 0) + deleted = true; + } + return deleted; + } + + parent = node->parent; + if (parent) { + unsigned int offset; + + offset = node->path >> RADIX_TREE_HEIGHT_SHIFT; + parent->slots[offset] = NULL; + parent->count--; + } else { + root_tag_clear_all(root); + root->height = 0; + root->rnode = NULL; + } + + radix_tree_node_free(node); + deleted = true; + + node = parent; + } while (node); + + return deleted; +} + +/** + * radix_tree_delete_item - delete an item from a radix tree * @root: radix tree root * @index: index key + * @item: expected item * - * Remove the item at @index from the radix tree rooted at @root. + * 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. + * 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(struct radix_tree_root *root, unsigned long index) +void *radix_tree_delete_item(struct radix_tree_root *root, + unsigned long index, void *item) { - /* - * The radix tree path needs to be one longer than the maximum path - * since the "list" is null terminated. - */ - struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; - struct radix_tree_node *slot = NULL; - struct radix_tree_node *to_free; - unsigned int height, shift; + struct radix_tree_node *node; + unsigned int offset; + void **slot; + void *entry; int tag; - int offset; - height = root->height; - if (index > radix_tree_maxindex(height)) - goto out; + entry = __radix_tree_lookup(root, index, &node, &slot); + if (!entry) + return NULL; - slot = root->rnode; - if (height == 0) { + if (item && entry != item) + return NULL; + + if (!node) { root_tag_clear_all(root); root->rnode = NULL; - goto out; + return entry; } - slot = indirect_to_ptr(slot); - - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; - pathp->node = NULL; - - do { - if (slot == NULL) - goto out; - - pathp++; - offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp->offset = offset; - pathp->node = slot; - slot = slot->slots[offset]; - shift -= RADIX_TREE_MAP_SHIFT; - height--; - } while (height > 0); - if (slot == NULL) - goto out; + offset = index & RADIX_TREE_MAP_MASK; /* - * Clear all tags associated with the just-deleted item + * Clear all tags associated with the item to be deleted. + * This way of doing it would be inefficient, but seldom is any set. */ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { - if (tag_get(pathp->node, tag, pathp->offset)) + if (tag_get(node, tag, offset)) radix_tree_tag_clear(root, index, tag); } - to_free = NULL; - /* Now free the nodes we do not need anymore */ - while (pathp->node) { - pathp->node->slots[pathp->offset] = NULL; - pathp->node->count--; - /* - * Queue the node for deferred freeing after the - * last reference to it disappears (set NULL, above). - */ - if (to_free) - radix_tree_node_free(to_free); - - if (pathp->node->count) { - if (pathp->node == indirect_to_ptr(root->rnode)) - radix_tree_shrink(root); - goto out; - } + node->slots[offset] = NULL; + node->count--; - /* Node with zero slots in use so free it */ - to_free = pathp->node; - pathp--; + __radix_tree_delete_node(root, node); - } - root_tag_clear_all(root); - root->height = 0; - root->rnode = NULL; - if (to_free) - radix_tree_node_free(to_free); + return entry; +} +EXPORT_SYMBOL(radix_tree_delete_item); -out: - return slot; +/** + * 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); @@ -1363,9 +1429,12 @@ int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) EXPORT_SYMBOL(radix_tree_tagged); static void -radix_tree_node_ctor(void *node) +radix_tree_node_ctor(void *arg) { - memset(node, 0, sizeof(struct radix_tree_node)); + 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) |